CA1234461A - Selectively permeable asymmetric membrane of polyetherimide - Google Patents
Selectively permeable asymmetric membrane of polyetherimideInfo
- Publication number
- CA1234461A CA1234461A CA000443877A CA443877A CA1234461A CA 1234461 A CA1234461 A CA 1234461A CA 000443877 A CA000443877 A CA 000443877A CA 443877 A CA443877 A CA 443877A CA 1234461 A CA1234461 A CA 1234461A
- Authority
- CA
- Canada
- Prior art keywords
- film
- pore diameter
- polymer
- dense layer
- diameter structure
- 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.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
- B01D69/127—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction using electrical discharge or plasma-polymerisation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/1213—Laminated layers
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
- C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
Abstract
ABSTRACT OF THE DISCLOSURE
A gas-selectively permeable membrane and a method of forming said membrane are described. This membrane is an asymmetrical pore diameter structure film made of a polyetherimide having the recurring unit represented by formula (A) or a mixture of said polyetherimide and at least one polymer having the recurring unit represented by formula (B), wherein the mean pore diameter of a dense layer of the asymmetrical pore diameter structure film is 0.5 micron or less and the mean thickness of the dense layer is 10 microns or less:
wherein x is a natural number including zero, Q is
A gas-selectively permeable membrane and a method of forming said membrane are described. This membrane is an asymmetrical pore diameter structure film made of a polyetherimide having the recurring unit represented by formula (A) or a mixture of said polyetherimide and at least one polymer having the recurring unit represented by formula (B), wherein the mean pore diameter of a dense layer of the asymmetrical pore diameter structure film is 0.5 micron or less and the mean thickness of the dense layer is 10 microns or less:
wherein x is a natural number including zero, Q is
Description
~`~34~
GAS-SELECTIVELY PERMEABLE MEMBRANE
AND METHOD OF FORMING SAID MEMBRANE
The present invention relates to a gas-selectively permeable membrane and a method of forming the membrane. More particularly, the present invention relates to a gas-selectively permeable membrane comprise in an asymmetrical pore diameter structure film of a polyetherimide or a polymer mixture containing said polyetherimide, or a composite gas-selectively permeable membrane comprising an asymmetrical pore diameter structure film of a polyetherimide or a polymer mixture containing said polyetherimide and at least one thin polymer film, particularly a plasma polymerization thin polymer film on the asymmetrical pore diameter structure film, and a method of forming such membranes.
BACKGROUND OF THE INVENTION
_ In recent years, extensive research has been conducted on the separation and purification of a fluid mixture using a selectively permeable membrane in place of conventional techniques based on a phase change such as distillation and freezing, which require a large amount of energy.
.'~'' I
Processes for separation and purification using sun a membrane which are presently in practical use on a commercial scale are directed mainly to liquid/liquid separation, such as the production of fresh water from sea water, disposal of waste water from factories, and concentration of foods, and liquid/solid separation. In connection with gas/gas separation, basically no process has yet been put to practical use. The major reasons for this are:
(l) selective permeability or gas selectivity is poor; that is, since no membrane is available which allows a specific gas to oats the-c-ethrough but does not essentially allow other gases to pass there through, it is necessary -to employ a multistage system in which membrane separation is repeatedly applied when a specific gas of high purity is to be produced. Aecordinglv, ~Iarcfe-'sïzed'~ëqu'ipme~nt~'~ls '*e'e'ded~;~and''
GAS-SELECTIVELY PERMEABLE MEMBRANE
AND METHOD OF FORMING SAID MEMBRANE
The present invention relates to a gas-selectively permeable membrane and a method of forming the membrane. More particularly, the present invention relates to a gas-selectively permeable membrane comprise in an asymmetrical pore diameter structure film of a polyetherimide or a polymer mixture containing said polyetherimide, or a composite gas-selectively permeable membrane comprising an asymmetrical pore diameter structure film of a polyetherimide or a polymer mixture containing said polyetherimide and at least one thin polymer film, particularly a plasma polymerization thin polymer film on the asymmetrical pore diameter structure film, and a method of forming such membranes.
BACKGROUND OF THE INVENTION
_ In recent years, extensive research has been conducted on the separation and purification of a fluid mixture using a selectively permeable membrane in place of conventional techniques based on a phase change such as distillation and freezing, which require a large amount of energy.
.'~'' I
Processes for separation and purification using sun a membrane which are presently in practical use on a commercial scale are directed mainly to liquid/liquid separation, such as the production of fresh water from sea water, disposal of waste water from factories, and concentration of foods, and liquid/solid separation. In connection with gas/gas separation, basically no process has yet been put to practical use. The major reasons for this are:
(l) selective permeability or gas selectivity is poor; that is, since no membrane is available which allows a specific gas to oats the-c-ethrough but does not essentially allow other gases to pass there through, it is necessary -to employ a multistage system in which membrane separation is repeatedly applied when a specific gas of high purity is to be produced. Aecordinglv, ~Iarcfe-'sïzed'~ëqu'ipme~nt~'~ls '*e'e'ded~;~and''
(2) gas permeability is poor; therefore, it is defoliate to -treat a large amount of a gas mixture. In particular, when gas selectivity is increased, gas permeability tends to drop, whereas when gas permeability is increased, gas selectivity tends to fall. this problem has not yet been satisfaetoril~ overcome.
lyrical membrane forming methods which have I been employed to prepare a satisfactory membrane include a method in which an asymmetrical pore diameter structure ~L~3~4~
membrane whose active skin layer is reduced in thickness as much as possible is formed by casting a polymer session, and a method in which a super thin membrane corresponding to the active spin layer is separately prepared and provided on a porous support to form a composite membrane. These methods to improve gas permeability are not always suitable for practical use because commercially available polymers fail to satisfy all desired physical properties; that is, commercially available polymers or copolymers are satisfactory in at least ogle of selective permeability, permeability, heat resistance, chemical resistance, strength, and so forth but are not satisfactory in other properties.
It has, therefore, been desired to develop polymers which are of high heat resistance and can be produced inexpensively. A typical example of such a polymer is a polysulfone. This polysulfone, however, is not satisfactory in respect of production cost.
SUE ANY OF TOE INVENTION
The present invention relates to:
a gas-selectively permeable membrane which is an asymmetrical pore diameter structure film made of a polye-therimide having the recurring unit represented by formula (A) as described hereinafter, or a mixture of the polyetherimide and at least one polymer having o ~:3~46~
the recurring unit represented by formula (B) as described hereinafter, wherein the mean pore diameter of a dense layer of the asymmetrical Gore diameter structure film is 0.5 micron or less and the mean thickness of the S dense layer it 10 microns or less; and a composite gas selectively permeable membrane comprising the asymmetrical pore diameter structure film as described above and at least one thin polymer film provided on the dense layer of the asymmetrical pore 0 diameter structure film; and a method of forming the yas-selectively permeable membrane as described above which comprises applying a solution containing the polyetherimide having the recurring unit represented by formula (A) as described hereinafter, or a mixture of the polyether-iliiide and at least one polymer having the recurring unit represented by~form.ula---(B)-as'described-hereinafter,~ --I
a solvent, and if desired or necessary, a swelling agent to form a film, bringing the thus-formed film into contact with a coagulating agent to remove the solvent, and then drying; and a method of forming the composite gas-selectively permeable membrane as described above which comprises further providing the thin polymer film on the I ~Jas-selectively permeable membrane.
..~.
~23~611 I ) I (B) BRIEF DISHPAN OF THE DOINGS
.
Figure l-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made o-f a 4:1 (weight ratio, hereinafter the same) mixture of aromatic polyester and polyetherimide (400 magnification);
Figure I is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter_structure.film made offal mixture of aroma-tic polyester and polyetherimide (200 magnification);
Figure l-c is a scanning electron microscopic p~okograph of the cross section of an asymmetrical pore diameter structure film made of a 1:4 mixture of aromatic polyester and polyetherimide (700 magnification);
Figure 2 is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a 4~1 mixture of polyp carbonate and polyetherimide (400 magnification);
GLUE
Figure 3 is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a 1:1 mixture of polysulfone and polyetherimide (400 magnification).
In all the photographs, the left upper portion is a dense layer.
jig. 4-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore limiter structure film made of polyetherimide(200 magnification wherein the left upper portion is a dense layer; and Fig. 4-b is an enlarged vie of the vicinity of the dense layer of Fig. pa (3,000 magnification).
l)f~TAILED DESCRIPTION OF THE INVENTION
.
The asymmetrical pore diameter structure -films are disclosed in, for example, S. Lob, S. Sourirajan, divan Chum. Ser., 33, 117 (1963) and U.S. Patent
lyrical membrane forming methods which have I been employed to prepare a satisfactory membrane include a method in which an asymmetrical pore diameter structure ~L~3~4~
membrane whose active skin layer is reduced in thickness as much as possible is formed by casting a polymer session, and a method in which a super thin membrane corresponding to the active spin layer is separately prepared and provided on a porous support to form a composite membrane. These methods to improve gas permeability are not always suitable for practical use because commercially available polymers fail to satisfy all desired physical properties; that is, commercially available polymers or copolymers are satisfactory in at least ogle of selective permeability, permeability, heat resistance, chemical resistance, strength, and so forth but are not satisfactory in other properties.
It has, therefore, been desired to develop polymers which are of high heat resistance and can be produced inexpensively. A typical example of such a polymer is a polysulfone. This polysulfone, however, is not satisfactory in respect of production cost.
SUE ANY OF TOE INVENTION
The present invention relates to:
a gas-selectively permeable membrane which is an asymmetrical pore diameter structure film made of a polye-therimide having the recurring unit represented by formula (A) as described hereinafter, or a mixture of the polyetherimide and at least one polymer having o ~:3~46~
the recurring unit represented by formula (B) as described hereinafter, wherein the mean pore diameter of a dense layer of the asymmetrical Gore diameter structure film is 0.5 micron or less and the mean thickness of the S dense layer it 10 microns or less; and a composite gas selectively permeable membrane comprising the asymmetrical pore diameter structure film as described above and at least one thin polymer film provided on the dense layer of the asymmetrical pore 0 diameter structure film; and a method of forming the yas-selectively permeable membrane as described above which comprises applying a solution containing the polyetherimide having the recurring unit represented by formula (A) as described hereinafter, or a mixture of the polyether-iliiide and at least one polymer having the recurring unit represented by~form.ula---(B)-as'described-hereinafter,~ --I
a solvent, and if desired or necessary, a swelling agent to form a film, bringing the thus-formed film into contact with a coagulating agent to remove the solvent, and then drying; and a method of forming the composite gas-selectively permeable membrane as described above which comprises further providing the thin polymer film on the I ~Jas-selectively permeable membrane.
..~.
~23~611 I ) I (B) BRIEF DISHPAN OF THE DOINGS
.
Figure l-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made o-f a 4:1 (weight ratio, hereinafter the same) mixture of aromatic polyester and polyetherimide (400 magnification);
Figure I is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter_structure.film made offal mixture of aroma-tic polyester and polyetherimide (200 magnification);
Figure l-c is a scanning electron microscopic p~okograph of the cross section of an asymmetrical pore diameter structure film made of a 1:4 mixture of aromatic polyester and polyetherimide (700 magnification);
Figure 2 is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a 4~1 mixture of polyp carbonate and polyetherimide (400 magnification);
GLUE
Figure 3 is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a 1:1 mixture of polysulfone and polyetherimide (400 magnification).
In all the photographs, the left upper portion is a dense layer.
jig. 4-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore limiter structure film made of polyetherimide(200 magnification wherein the left upper portion is a dense layer; and Fig. 4-b is an enlarged vie of the vicinity of the dense layer of Fig. pa (3,000 magnification).
l)f~TAILED DESCRIPTION OF THE INVENTION
.
The asymmetrical pore diameter structure -films are disclosed in, for example, S. Lob, S. Sourirajan, divan Chum. Ser., 33, 117 (1963) and U.S. Patent
3,775,308.~ These films com~risë:a-dense~layer Andy non-dense porous) layer.
us stated above, polysulfones typically have the defects that gas permeability is poor, although they are superior in heat resistance, chemical resistance, strength, and so forth.
In order to overcome the foregoing problem, in thy? present invention, the asymmetrical pore diameter 2'j structure film is formed using a polyetherimide or a pourer mixture containing the ~olye~herimide in ~L~23~46~
place of ~olysulfone.
That is, one of the features of the present invasion is Jo use as a raw material for the asymmetrical Gore diameter structure film a polyetherimide, or a polymer mixture containing said polyetherimide, which is different from polysulfone, is inexpensive end has high heat resistance.
The polyetherimides used herein are polymers having a molecular weight of 10,000 to 50,000 an lo preferably 25,000 to 40,000, and the recurring unit represented by formula (A):
No ;~_ I No (~) and are prepared by condensation reaction of phonics-phenyldicarboxylic acid androids touch as Boyce-, .. . ... . . . .
(3,4-dicarboxyphenoxy) phenol propane android) and phenylenediamines (such as methapllenylenediamine).~ In the phenoxyphenyldicarboxylic acid androids, the car boxy and phonics groups may be located at 3,3'-, 4,4'- or 3,4'-positions. In addition, a mixture of such 3,3'-, 4,4'- and substituted compounds may be used. Although it is most preferred for the propane to take a -C(CH3)2- structure, it may be -CH2-CH2-CH2- or -CH2-CH(CH3)-. In -Shannon-other than the propane, n may be within the range of from 1 to 8.
39~6~
The method for preparing the polyetherimides are disclosed in, for example, U.S. Patent-3, 852,242.
The polymers mixed with the polyetherimides have the recurring unit represented by formula By - O Q I BYWAY
wherein x is a natural number including zero (0), SHEA O
and Q is -C- or So and Z is - Al r SHEA O O
a C - r C or SHEA
OH
OH ~C-CH -H
The above polymers hays a molecular weight of 10,000 to 50,000~ Typical examples of such polymers are as hollows:
Polycarbonates having the recurring unit represented by the formula:
SHEA
SHEA
. ;. Jo - .
I
Aromatic polyesters having the recurring unit represented by the formula:
O o SHEA
oily icky /~}
C~3 .
Polysulfones having the recurring unit repro-sensed by the formula:
I
or . . = . . . . .. , . -- ... .. . . . . . . ... .. . = . = =
o SHEA
The polyetherimide or the polymer mixture containing the polye-therimide can be dissolved in ~hlorine-based solvents, such as chloroform and -trichloro-ethylene cyclic ether solvents, such as tetrahydrofuran and Dixon, aside solvents, such as dimethylformamide, ~l~3~6~
or nitrogen-containing cyclic solvents, such as N--methvl-2-pyrrolidone, N-formylpiperidine, and l-formylmorp~oline.
Of these solvents, the c~.~lorine-based solvents and cyclic ether solvents can dissolve the polyetherimide or the polymer mixture -therein easily up to a concentration ox' 10% by weight based on the resulting solution, but if the concentration exceeds 15% by weight, same basis, many of the resulting solutions -tend to become viscous rapidly On -the other hand, the aside solvents and nitrogen-containing cyclic solvents exhibit a high ability to dissolve therein the polyetherimide or the polymer mixture; that is, the ~olye-therimide or the polymer mixture is soluble even up -to a concentration of 20 to 30% by weigh-t, same basis, without causing problems such as a serious increase in viscosity, excess size phase separation, and precipitation. Thus, of the solvents~as-described above, the aside and nitrogen- -containing cyclic solvents are particularly preferred.
The polymer concentration in the solvent is about 5 to by weight, and preferably 15 to 35~ by weight.
The above-described solvents can be used individually or in combination with one another. 'Lyon a mixture of a solvent having a relatively high Helen point (e.g., dimethylformamide) with a solvent having a relatively low boiling point (e.g., tetrahydroEuran and ~4~6~
1 dichloromethane) is used, the mean pore diameter of a dense layer obtained can be reduced or the mean thickness of the dense layer can be increased.
It is also possible to add to the above-described solvent or solvent mixture an inorganic or organic swelling agent. Examples of inorganic swelling agents include halogen ides, nitrates and sulfates of alkali metals or alkaline earth metals, such as lithium chloride, potassium chloride, lithium bromide, potassium bromide, lithium nitrate and magnesium sulfate. They are used in an amount of 200 parts by weight or less, and preferably 150 parts by weight or less for 100 parts by weight of the polyetherimide or the polymer mixture containing the polyetherimideO
Examples ox the organic swelling agent include ethylene glycol, diethylere glycol, polyethylene glycol and methyl ether derivatives thereof, polypropylene glycol and derivatives thereof, and polyhydric alcohol such as glycerin and 1,3-propanediolO They are used in the same amount or somewhat larger amount Han the inorganic swelling agents described above. By the addition of the swelling agent the mean pore diameter of a dense layer obtained can be increased or the mean thickness of the dense layer can be reduced. Further, when a non-dense (porous) layer obtained has a relatively small pore I
diameter, the diameter can be increased 'Dye the addition of the swelling agent.
The thus prepared solution is uniformly slowed onto a support plate by means of a doctor knife and -then golfed by dipping in a non-solvent, that is, a coagulate in agent, usually water, or golfed after partial evapo-ration of the solvent in the solution to form an asymmetrical pore diameter structure film of the polye-therimide or the polymer mixture containing the polyetherimide. Of course, a tubular member can be formed using a tubular nozzle.
The structure and characteristics of the asymmetrical pore diameter structure film are influenced by the type of the polymer, the mixing ratio of the polymer mixture, the concentration of the solution, the type of the solvent, -the amount of the additive, and so =: Jo -- .. ... . . .. . .. . ... . ......... I-- . .. ._.= . _ _ ._ =__=__ = _ __.. _ _,._ .....
forth. In general, as the concentration is increased, gas selective permeability increases, but gas permeably-try drops. us the mixing ratio of the polymer to the polyetherimide approaches I weight ratio, herein-after the same), the mean pore diameter increases and the was permeability increases, but the gas selective per,lleability drops.
Thea effects will hereinafter be explained with reference to the accompanying photographs.
-- I -o ~3~L6~
Figure l-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a I mixture of polyp etherimide and aromatic polyester.
Figure 2 is a scanning electron microscopic photograph of the cross section of an asJ~me-trl'cal pore diameter structure film made of a I mixture of polyether-imide and polycarbonate.
In the asymmetrical pore diameter structure film of Figure l-a, inner pores extend -to the bottom surface vertically relative to the surface of -the film and are oriented in a regular pattern as compared wit those in Figure 2. Furthermore, the sponge structure of the walls partitioning the inner pores is denser than that of Figure 2.
This difference is due to a difference in the solubiIity~parameter between the aromatic pulsator and polyp carbonate. A difference in compatibility button polyetherimide/aromatic polyester and polyetherimide/poly-carbonate results in the difference in the asy~metricalpore diameter film structure. Hence, by using polymers having different computabilities, it is possible to change the asymmetrical pore diameter Elm structure, the mean pore diameter and gas permeabiiitv. The use of combination of polymers having good compatibility to o each other can provide a regularly disposed asymmetrical structure.
Figure lo is a scanning electron microscopic photograph of the cross section of an asymmetrical pare 3 diameter structure film made of a lo mixer of polyether-imide and aromatic polyester, and Figure l-c is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a Al mixture of polyetherimide and aromatic polyester.
lo The structures shown in Figures l-a and l-c are nearly equal. In Figure lo Hoover, there can be . found regularly oriented longitudinal pores which can be observed in Figures 1-a and 1-c only in the united areas near the dense Layer, and a sponge-like structure having a large Jean pore diameter is observed in the structures.
At a mixing ratio at which the contact interface between different polymers-increases, *hat-is, generall~-a~mi-~ing.-ratio approaching lo the reduction in compatibility between the different polymers reaches a maximum. The characteristics of such a dope solution are responsible for the distortion of the structure in the asymmetrical pore diameter structure film, an increase in the mean pore diameter and irregularity of the surface dense layer. This demonstrates that the structure of the asymmetrical pore diameter structure film, the mean pore diameter and gas permeability can be changed by control-lying -toe mixing ratio of the polymers.
fly Another feature of the resent invention is that on the surface of the dense layer side of the asymmetrical pore diameter structure film described above a thin polymer film of high gas permeability is laminated or a plasma polymerization thin film is deposited by glow discharge to obtain the composite film having a further improved gas permeability.
rJ` This feature is preferably applied Tao as~nmetrical pore diameter structure film having a relatively low gas selective permeability.
When the mean pore diameter of the dense layer is 0.001 micron or less, t-he-origin~l-gas selec-tive~perm;ëability is exhibited, but when it exceeds 0.01 micron, the selective permeability is relatively low.
Within this pore diameter range, selective permeability can be recovered by laminating a thin film through, e.g., diving in a different polymer solution .... .. . ..... . . ...... .. ... .. . . . . . . . .... .. .. . ..
or direct plasma polymerization.
When the mean pore diameter of the dense layer is within the range of from 0.1 to 0.5 micron, it is preferred to slightly increase the thickness of the asymmetrical Gore diameter structure film by increasing the thickness of the coated polymer layer and the concentration of the polymer.
Nina, however, the mean pore diameter exceeds 0.5 micron, it becomes difficult to form a polymer film having high gas selective permeability.
~L~23~6~
The thickness of the thin polymer film formed by lamination is about 50 microns or less and preferably about 30 microns or less, however, the thickness can be further reduced within a range such that the pores in the dense layer can be closed or plugged by the lamination. The thickness of the thin polymer film formed by plasma polymerization is about 1 micron or less, and preferably about 0~3 micron or less.
A thin film of a rubber-based polymer such as polysiloxane is preferably laminated on the asymmetrical pore diameter structure film In order to prepare a composite membrane of high selectivity preferably a plasma polymerization thin film is deposited on the asymmetrical r pore diameter structure film on the dense layer side thereof directly or after the lamination of the rubbex-based polymer thin film thereto. High permeability can be maintained by depositing a super thin polymer film of ] micron or less and furthermore, as a raw material for use in polymerization a compound of high gas selective permeability can be chosen from a wide range.
In this feature of the present invention, the mean pore diameter of the dense layer is adjusted within a range such that the pores can be closed or plugged by the formation of deposition of the plasma polymerization ' I
-film. If the Jean pore diameter of the dense layer is more -than 0.1 micron, the pores cannot be plugged by the plasma polymerization film. On the other hand, if the mean pore diameter is 0.001 micron or less, the pores can be easily plugged, but gas permeability seriously drops. As a matter of course, the mean pore diameter kick can be plugged by -the plasma polymerization film varies slightly depending on the type of the monomer and the plasma polymerization conditions In the present invention, the mean pore diameter of the dense layer is US micron or less, however, in this feature of the present invention i-t is cJenerally referred that the mean pore diameter is in the range between 0.01 and 0.1 micron.
monomers for use in the plasma polymerization will hereinafter be explained.
It is known that various monomers such as ethylene'and-,ace-tvlene~undergo-pl-asma polymerization in -Jan atmosphere in which a glow discharge is applied. In tile resent invention, it is referred to use compounds hiving a tertiary carbon-containing group (C-5H-C) as a functional grout and organosilane commends. Examples of such tertiary carbon-containing compounds include tert-but~l compounds such as tert--butylamine, pontoon ~:3~6~L
derivatives such as 4-methyl-l-penten~, octanes such as l-octane and isoprene.
Organosilane compounds which can be used include tetramethylsilane~ hexamethylsilane, methyldichlorosilane, and methy.ltrichlorosilaneO More preferred are organosilanecompunds contain gin an unsaturated bond, such as trimethylvinylsilane, dimethylvinylchlorosilane, vinyltrichlorosilane, methylvinyldichlorosilane, meth:Ltrivinylsilane, allyltrimethylsilane~ and ethynyltrimethylsilaneO
A gas-selectively permeable membrane is preferably prepared by depositing a plasma polymerization thin film directly on the dense layer of an asymmetrical pore diameter structure film of the polyetherimide or the polymer mixture continuing the polyetherimidej having a pore diameter range of from 0.001 to 0.1 micron It is required for the raw materiel for use in the preparation of the film to have superior characteristics It is further necessary that the thiclcness of the plasma polymerization thin film, which 20 . controls the permeability of the membrane., should be reduced to the lowest possible thickness The reason for this is as follows.
The characteristics of the raw material]. are evaluated by the gas permeation coefficient thereof:
P = cm3 . cm/cm2 O succumb Hug -18~
J
TV I
which is calculated with the thickness of the raw material as 1 cm. On the other hand, the characters-3 1` e tics of the composite membrane Jo evaluated by the permeation Wright the thickness of the raw material S itself:
Q = cm3/c~2 succumb Hug Hence, the permeation rate of a 1 micron thick membrane is ten times that of a 10 micron thick membrane although their permeation coefficients are the same. Hence, the characteristics required actually are the permeation rate and the thickness of -the membrane.
Lo the present invention, the asymmetrical pore diameter structure film made of the polyether-imide or the polymer mixture containing the polyether-imide Andy further a second polymer, having a rorediameter range as described above is dried and, there-after, a plasma polymerization layer is. deposited ox the . . .
surface of the dense layer in a thickness of 1 micron or less, preferably 0.3 micron or less. For examDlel the pressure of the plasma polymerization chamber it lowered to 5 torn or less, preferably 2 torn or less, a mixed yes of an unpolymerizable gas end a polvmerizable cJas is introduced into -the chamber, and when a high frequency ~23~
glow discharge is applied at a redetermined ought of, eye., from 5 to 500 I preferably about Jo To the polymerizable gas undergoes plasma polymerization, depositing as a thin film on the surface of the dense layer of the asymmetrical pore diameter structure film.
The thickness of the -thin film increases nearly in proportion to-the time of glow discharge or the flow I, rate of the polymerizable gas and, therefore, it-can be : .:
adjusted -to an appropriate value. Furthermore, as-the --output of glow discharge is increased our decreased the thickness of the deposited film increases or decreases. ,,.,:.
These film-forming conditions can be easily optimized by one skilled in the art. In any case it is necessary in the present invention that a defect-free uniform polymerization film be deposited at a thickness as described-above :~,--.,.
One of the~criteri-a-in selecting the polymerize --------able gas is that the plasma polymerization thin film prepared therefrom prevents as much as possible the- ---passage ozone component of a mixed gays tub separate since the thickness of the plasma polymerization thin film is as low as 1 micron and.pre:Eerably 0.3 micron or less. Plasma polymerizable monomers commonly used, such as ethylene and screen, satisfy the criterion as described above...IIowever;:-comnounds-:-containing a -: :
I
tertiary carbon as a functional group as described above are preferred for use in the nresen-'c invention. More preferred are those compounds further containing a double bond. In addition, the organosilane compounds as described above are preferred for use in the present --invention. Of these organosilane compounds, compounds - -containing an unsaturated functional group such as a .-. , double bond or triple bounder more referred.
Plasma polymerization techniques which can be : ..
utilized in the preserlt.invention are disclosed in detail in US Patent 3,84.7,652.
In using an asymmetrical Gore diameter struck Tory film made of a polyetherimide or a polymer' mixture containing said polyetherimide and having a mean pore diameter o-f 0.1 micron or more, it is prefer-red to deposit thereon a thin film of a polymer having .
- high gaspermeability.~.''Silicone''r'ubbers.such;'as.,.olLowe '''' -I
dim ethyl selection are preferred from the viewpoint of gas permeability and heat resistance. In particular TV type and LTV-tvpe silicone rubbers, both being low temperature vulcanization type and of the two-pac!~-reac~...,:. -lion type, are convenient-for:use -in impregnation into. :.. I.
the interior of fine pores in the asymmetrical pore diameter-structure~i-film Orion reactions after the impregnation since they become polymeric compounds .. .
31 ~3~4Ç~i~
undergoing the condensation-and addition-reactions -described below.
-Sue Russ- -I --Swiss- -I ROW (1) I ! I I
-Sue + Hess- -I -Swiss- -I H O (2) I I . I 1 2 1 12 H it I' loquacious_ - (3) They're also convenient in that before the reaction- -they-can reconverted innately viscosity solution ..
with whic'n.the pores of the asymmetrical pore-diameter. ------ ---- ---structure-film of the present invention can be easily -impregnated.
As one technique to increase gas selectivepermeability,~a plasma polymerization thin film can - furth~er--he..dë~o-sited on-the'comp'os'ite'~atèria~~-h2ving-a'-silicone rubber laminated thereto. Another tuitions. :., that where a plasma polymerization thin film is deposited on the asymmetric pore diameter structure film of. the -....
pol.yetherimide I. or the polymer mixture containing the ...
polyetherimide and then the silicone rubber is- -laminated on the plasma-polymerization thin film. --I ..'~. The F.resen-t.,inv.ention .is::described.in-'greater-,--~--c -detail by reference to the following Examples.' I
of E,~P1E
A dope solution was prepared, consisting of 10~
by White of polyetherimide, ULTEM-1000 produced ho - -General Electric Co.), 40% by weight of N-methyl-2-pyrrolidone, and 50% by weight of tetrahydrofuran.ULT~ 1000 has thè.recurring unit shown below and nay à
molecular weight of about 32,000.:
I eye This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a ..... doctor.. nephew The entire-glass~plate was-soaked-in-~ a-;
distilled water at room temperature to coagulate the dope solution. The.thus-formed.film was peeled off, washed with water pharaoh hours, android by blowing air at 45C for 2 hours to prepare about a-90 micron thwack asymmetrical-pore..diameter structure film. : ...
Scanning electron microscopic analysis showed . ...
that thwackers section-of:.the.:film Houdini asymmetrical pore diameter structure.
cue ok ~1~34~6~
The gas permeation characteristics of the film were measured using air as a feed gas. The oxygen permeation rate Q2 was about 3.2xlO 6 cm3/cm sea cm Hug, and the oxygen/nitrogen selectivity a (oxygen permeation rate/nitrogen permeation rate) was about 4 9.
The oxygen permeation rate per centimeter of thickness, i.e., the oxygen permeation coefficient, POX
(calculated from --2) was about 2.9xlO 8 cm3 cm/cm2 sea cm Hug.
A dope solution was prepared, consisting of 20% by weight of the polyetherimide Ultra and 80%
, Jo.
by weight of N-methyl-2--pyrrolidone.
This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a doctor knife. The entire glass plate was soaked in distilled water at room temperature to coagulate the dope solution. The thus-forrned film was peeled off, washed with water for 2 hours, and dried by blowing air at 45C for 2 hours to prepare about a 150 micron thick asymmetrical pore diameter structure film.
The gas permeation characteristics of the film were measured in the same manner as in Example 1 and the results were as follows:
Q2 - 2.0xlO 5 cm3/cm2-sec-cm Hug PO - 3 Ox10-7 cm3-cm/cm2.sec.cm Hug * ~rclcJe Jo - 24 -~L23~
Scanning electron microscopic analysis showed that the cross section of the film had an asymmetrical pore diameter structure as shown in Figure pa and 4b.
A dope solution was prepared, consisting of 16~ by weight of polysulfone (Duel P-170~ produced by U.C.C.), 4% by weight of the polyetherimide, ULTE~I-1000~, 60% by weight of N-methyl-2--~yrrolidone, and 20% by weight of tetrahydrofuran.
Duel Pus the recurring unit shown below and has a molecular weight of about 28,000.
O SHEA
O C~3 This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a doctor knife and was allowed to stand for 2 minutes. At the end of -the time, the entire glass plate was soaked in distilled water at room temperature to coagulate the dope solution. The thus-formed film was peeled off, washed with water for 2 hours, and dried by blowing air 20 at 45C for 2 hours to prepare about a 120 micron thick asymmetrical pore diameter structure film.
jrrc~Je JAR ok -- 2 s ~3g~
It was confirmed by scanning electron micro-scopic analysis that the cross section of -the film had an asymmetrical pore diameter structure.
The gas permeation characteristics of the film were as follows:
Q2 - ~,5xlO 6 cm3/cm2~sec~cm Hug POX - laxly 7 cm3 cm/cm2 succumb Hug , 2.1 Asymmetrical pore diameter structure films were prepared in the same manner as in Example 1 except that dope solutions having the compositions as shown in Table 1 were used.
The thickness and gas permeation characters-tics of each film are shown in Table 2.
It was confirmed by scanning electron micro-scopic analysis that the cross section of the film had .. .. . . . ..
an asymmetrical pore diameter structure.
CO1~1PA~TIVE EXPEL
A dope solution was prepared, consisting of ?~'~ by weight of the polysulfone, Duel P-1700~ and I
by weight of N-methyl-2-pyrrolidone.
This dope solution was flowed over a smooth glass plate in a thickness of 150 microns by means of a doctor knife and, thereafter, dried in an atmosphere of air maintained at 250C for 2 hours to prepare about a 'rouge I
~3~L6~
23 micron thick dense film The specific gravity of the film was Lowe To gas permeation characteristics of the film were as follows:
Q0 - 9 lxlO-8 cm3/cm2-sec~cm Hug P02 -I 2.1xlO 10 cm3~cm/cm~-sec~cm Ho a -O 600 COMPARATIVE EXILES 2 To 4 Dense films were prepared in the same manner lo as in Comparative Example 1 except that dope solutions having the compositions as shown in Table 3 were used_ ;
The thickness Suzuki gravity and gas permeation characteristics of each film are shown in Table 40 lo EXAMPLE 8 on asymmetrical pore diameter structure film was prepared in-the--sam~ manner -as-i~-Example Z. -~~
solution consisting of I by weight of silicone rubber (I 0 2) (an equimolar mixture Of vinyl selection and JO hydrogen selection both having a viscosity of-about 7 r (poise) and 80% by weight of Freon 113 (trifluorotrichlc,r~r~
ethanes produced by Deacon Cage Co., Ltd.) was coated on the asymmetrical pore diameter structure film as prepared above on the dense layer side thereof in a thickness of 150 microns and vulcanized with hot air at 120C for 4 minutes to prepare and composite membrane.
trade Mark 27-~L23~
The gas permeation characteristics of the composite membrane were as follows: :
Q2 = 7~1 X 10 cm3/cm2 O succumb Hug = 2~9 A composite membrane was prepared in the same manner as in Example I This composite membrane was place in a reaction chamber, a a glow discharge was applied at an output of 20 w while introducing trimethylvinylsilane at a . flow rate of OWE cm 8/mln to deposit a plasma polymerization film on the outermost layer of the dense layer side of the composite membrane.
The gas permeation characteristics of the three-layer composite membrane as prepared above were as follows:
.
QUEUE - 8.7 X 10-~ cm3~cm2 . succumb Hug I= 5.8 An asymmetrical pore diameter structure film was prepared in the same manner as in Example 5. A solution consisting of 20% by weight of the silicone rubber (I= 21 which is the same as used in Example 8 and 80% by weight of Freon 113* was coated on the surface of a dense layer of the symmetrical pore diameter structure film in a thickness of 140 microns and vulcanized *Trade Mark -28-~34~
with hot air at 170C for 30 minutes to prepare a composite membrane The gas permeation characteristics of the composite membrane were as phallus:
Q2 0 609xlO 6 m3!cm~cS~ cm Hug Eg~PLE 11 _ _ .
A composite membrane was prepared in the same manner as in example in except that an asymmetrical Gore diameter structure film as repoured it the same manner as in Example 6 was used Thea gas poinciana characteristics of the composite me3nbrane were as follows:
Q0~--9 o 8xlO 6 cm3/cm2-sec cm Hug a .- 2~2 E~'~2~LE 12 A composite membrane was prepared in the same manner as in Example loo This composite membrane was placed i~.a.xeaction chamber, an a glow discharge was- --applied at an output of 20 w for 30 minutes while introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization film on the outermost layer of the dense layer side of the composite membrane The gas permeation characteristics of the three-layer composite membrane as prepared above were as follows:
.
I
Q2 -. l.9X10 6 cm /cm2 sea cm Hug -. 3.5 E~IPLE 13 An asymmetrical none diameter structure film was prepared in the same manner as in Example 2 except that a dope solution consisting of 20% by weight of the polyetherimide, LUTE 1000~, 60% by weight of N-methyl-2-pyrrolidone, and 20% by weight of tetrahydrofuran was used.
The gas permeation characteristics of the asymmetrical pore diameter structure film were as follows:
Q2 - g Oslo 6 cm3/cm2~sec cm Hug -. 1.4 This asymmetrical pore diameter structure film was placed in a reaction chamber, and a glow discharge rJas applied at an output off w for 30 Monticello .:
introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization film on the surface of the dense layer.
The gas permeation characteristics of the composite membrane as prepared above were as follows:
Q2 . 3.1xlO cm3/cm succumb Hug I
Jo I
EXPEL I
An asymmetrical pore diameter structure film was prepared in the same manner as in Example 3. This asymmetrical pore diameter structure film was placed in a reaction chamber, and a glow discharge was applied at an output of 20 w for 30 minutes while introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization filmlon the dense layer of the asymmetrical pore diameter structure film.
The gas permeation characteristics of tile composite membrane as prepared above were as follows:
Q2 -. 2.6xlO 6 cm3/cm2~sec~cm Hug -, 3.7 . _ _ _ _ . _ .. , .. _ _ , . _ ., _ __ .. _ _ _ _ . ,__ . _. , _ __ _ __ _ _ _, _, _ _, .. , _ _ _. _. _ ._ _ _ _, ... -- I_ -- , _ _ .... , -- -- . _ _ _ = .. ---- ... -- : -- -- -- -- --. _ .. -- --. -- .. --' ' : , = ---- -- -- , -- . _ 1.. --': ' 123~
Dope Solution Polymer I Polymer II Solvent Example Polymer wit% Polymer wit% Solvent wit%
us stated above, polysulfones typically have the defects that gas permeability is poor, although they are superior in heat resistance, chemical resistance, strength, and so forth.
In order to overcome the foregoing problem, in thy? present invention, the asymmetrical pore diameter 2'j structure film is formed using a polyetherimide or a pourer mixture containing the ~olye~herimide in ~L~23~46~
place of ~olysulfone.
That is, one of the features of the present invasion is Jo use as a raw material for the asymmetrical Gore diameter structure film a polyetherimide, or a polymer mixture containing said polyetherimide, which is different from polysulfone, is inexpensive end has high heat resistance.
The polyetherimides used herein are polymers having a molecular weight of 10,000 to 50,000 an lo preferably 25,000 to 40,000, and the recurring unit represented by formula (A):
No ;~_ I No (~) and are prepared by condensation reaction of phonics-phenyldicarboxylic acid androids touch as Boyce-, .. . ... . . . .
(3,4-dicarboxyphenoxy) phenol propane android) and phenylenediamines (such as methapllenylenediamine).~ In the phenoxyphenyldicarboxylic acid androids, the car boxy and phonics groups may be located at 3,3'-, 4,4'- or 3,4'-positions. In addition, a mixture of such 3,3'-, 4,4'- and substituted compounds may be used. Although it is most preferred for the propane to take a -C(CH3)2- structure, it may be -CH2-CH2-CH2- or -CH2-CH(CH3)-. In -Shannon-other than the propane, n may be within the range of from 1 to 8.
39~6~
The method for preparing the polyetherimides are disclosed in, for example, U.S. Patent-3, 852,242.
The polymers mixed with the polyetherimides have the recurring unit represented by formula By - O Q I BYWAY
wherein x is a natural number including zero (0), SHEA O
and Q is -C- or So and Z is - Al r SHEA O O
a C - r C or SHEA
OH
OH ~C-CH -H
The above polymers hays a molecular weight of 10,000 to 50,000~ Typical examples of such polymers are as hollows:
Polycarbonates having the recurring unit represented by the formula:
SHEA
SHEA
. ;. Jo - .
I
Aromatic polyesters having the recurring unit represented by the formula:
O o SHEA
oily icky /~}
C~3 .
Polysulfones having the recurring unit repro-sensed by the formula:
I
or . . = . . . . .. , . -- ... .. . . . . . . ... .. . = . = =
o SHEA
The polyetherimide or the polymer mixture containing the polye-therimide can be dissolved in ~hlorine-based solvents, such as chloroform and -trichloro-ethylene cyclic ether solvents, such as tetrahydrofuran and Dixon, aside solvents, such as dimethylformamide, ~l~3~6~
or nitrogen-containing cyclic solvents, such as N--methvl-2-pyrrolidone, N-formylpiperidine, and l-formylmorp~oline.
Of these solvents, the c~.~lorine-based solvents and cyclic ether solvents can dissolve the polyetherimide or the polymer mixture -therein easily up to a concentration ox' 10% by weight based on the resulting solution, but if the concentration exceeds 15% by weight, same basis, many of the resulting solutions -tend to become viscous rapidly On -the other hand, the aside solvents and nitrogen-containing cyclic solvents exhibit a high ability to dissolve therein the polyetherimide or the polymer mixture; that is, the ~olye-therimide or the polymer mixture is soluble even up -to a concentration of 20 to 30% by weigh-t, same basis, without causing problems such as a serious increase in viscosity, excess size phase separation, and precipitation. Thus, of the solvents~as-described above, the aside and nitrogen- -containing cyclic solvents are particularly preferred.
The polymer concentration in the solvent is about 5 to by weight, and preferably 15 to 35~ by weight.
The above-described solvents can be used individually or in combination with one another. 'Lyon a mixture of a solvent having a relatively high Helen point (e.g., dimethylformamide) with a solvent having a relatively low boiling point (e.g., tetrahydroEuran and ~4~6~
1 dichloromethane) is used, the mean pore diameter of a dense layer obtained can be reduced or the mean thickness of the dense layer can be increased.
It is also possible to add to the above-described solvent or solvent mixture an inorganic or organic swelling agent. Examples of inorganic swelling agents include halogen ides, nitrates and sulfates of alkali metals or alkaline earth metals, such as lithium chloride, potassium chloride, lithium bromide, potassium bromide, lithium nitrate and magnesium sulfate. They are used in an amount of 200 parts by weight or less, and preferably 150 parts by weight or less for 100 parts by weight of the polyetherimide or the polymer mixture containing the polyetherimideO
Examples ox the organic swelling agent include ethylene glycol, diethylere glycol, polyethylene glycol and methyl ether derivatives thereof, polypropylene glycol and derivatives thereof, and polyhydric alcohol such as glycerin and 1,3-propanediolO They are used in the same amount or somewhat larger amount Han the inorganic swelling agents described above. By the addition of the swelling agent the mean pore diameter of a dense layer obtained can be increased or the mean thickness of the dense layer can be reduced. Further, when a non-dense (porous) layer obtained has a relatively small pore I
diameter, the diameter can be increased 'Dye the addition of the swelling agent.
The thus prepared solution is uniformly slowed onto a support plate by means of a doctor knife and -then golfed by dipping in a non-solvent, that is, a coagulate in agent, usually water, or golfed after partial evapo-ration of the solvent in the solution to form an asymmetrical pore diameter structure film of the polye-therimide or the polymer mixture containing the polyetherimide. Of course, a tubular member can be formed using a tubular nozzle.
The structure and characteristics of the asymmetrical pore diameter structure film are influenced by the type of the polymer, the mixing ratio of the polymer mixture, the concentration of the solution, the type of the solvent, -the amount of the additive, and so =: Jo -- .. ... . . .. . .. . ... . ......... I-- . .. ._.= . _ _ ._ =__=__ = _ __.. _ _,._ .....
forth. In general, as the concentration is increased, gas selective permeability increases, but gas permeably-try drops. us the mixing ratio of the polymer to the polyetherimide approaches I weight ratio, herein-after the same), the mean pore diameter increases and the was permeability increases, but the gas selective per,lleability drops.
Thea effects will hereinafter be explained with reference to the accompanying photographs.
-- I -o ~3~L6~
Figure l-a is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a I mixture of polyp etherimide and aromatic polyester.
Figure 2 is a scanning electron microscopic photograph of the cross section of an asJ~me-trl'cal pore diameter structure film made of a I mixture of polyether-imide and polycarbonate.
In the asymmetrical pore diameter structure film of Figure l-a, inner pores extend -to the bottom surface vertically relative to the surface of -the film and are oriented in a regular pattern as compared wit those in Figure 2. Furthermore, the sponge structure of the walls partitioning the inner pores is denser than that of Figure 2.
This difference is due to a difference in the solubiIity~parameter between the aromatic pulsator and polyp carbonate. A difference in compatibility button polyetherimide/aromatic polyester and polyetherimide/poly-carbonate results in the difference in the asy~metricalpore diameter film structure. Hence, by using polymers having different computabilities, it is possible to change the asymmetrical pore diameter Elm structure, the mean pore diameter and gas permeabiiitv. The use of combination of polymers having good compatibility to o each other can provide a regularly disposed asymmetrical structure.
Figure lo is a scanning electron microscopic photograph of the cross section of an asymmetrical pare 3 diameter structure film made of a lo mixer of polyether-imide and aromatic polyester, and Figure l-c is a scanning electron microscopic photograph of the cross section of an asymmetrical pore diameter structure film made of a Al mixture of polyetherimide and aromatic polyester.
lo The structures shown in Figures l-a and l-c are nearly equal. In Figure lo Hoover, there can be . found regularly oriented longitudinal pores which can be observed in Figures 1-a and 1-c only in the united areas near the dense Layer, and a sponge-like structure having a large Jean pore diameter is observed in the structures.
At a mixing ratio at which the contact interface between different polymers-increases, *hat-is, generall~-a~mi-~ing.-ratio approaching lo the reduction in compatibility between the different polymers reaches a maximum. The characteristics of such a dope solution are responsible for the distortion of the structure in the asymmetrical pore diameter structure film, an increase in the mean pore diameter and irregularity of the surface dense layer. This demonstrates that the structure of the asymmetrical pore diameter structure film, the mean pore diameter and gas permeability can be changed by control-lying -toe mixing ratio of the polymers.
fly Another feature of the resent invention is that on the surface of the dense layer side of the asymmetrical pore diameter structure film described above a thin polymer film of high gas permeability is laminated or a plasma polymerization thin film is deposited by glow discharge to obtain the composite film having a further improved gas permeability.
rJ` This feature is preferably applied Tao as~nmetrical pore diameter structure film having a relatively low gas selective permeability.
When the mean pore diameter of the dense layer is 0.001 micron or less, t-he-origin~l-gas selec-tive~perm;ëability is exhibited, but when it exceeds 0.01 micron, the selective permeability is relatively low.
Within this pore diameter range, selective permeability can be recovered by laminating a thin film through, e.g., diving in a different polymer solution .... .. . ..... . . ...... .. ... .. . . . . . . . .... .. .. . ..
or direct plasma polymerization.
When the mean pore diameter of the dense layer is within the range of from 0.1 to 0.5 micron, it is preferred to slightly increase the thickness of the asymmetrical Gore diameter structure film by increasing the thickness of the coated polymer layer and the concentration of the polymer.
Nina, however, the mean pore diameter exceeds 0.5 micron, it becomes difficult to form a polymer film having high gas selective permeability.
~L~23~6~
The thickness of the thin polymer film formed by lamination is about 50 microns or less and preferably about 30 microns or less, however, the thickness can be further reduced within a range such that the pores in the dense layer can be closed or plugged by the lamination. The thickness of the thin polymer film formed by plasma polymerization is about 1 micron or less, and preferably about 0~3 micron or less.
A thin film of a rubber-based polymer such as polysiloxane is preferably laminated on the asymmetrical pore diameter structure film In order to prepare a composite membrane of high selectivity preferably a plasma polymerization thin film is deposited on the asymmetrical r pore diameter structure film on the dense layer side thereof directly or after the lamination of the rubbex-based polymer thin film thereto. High permeability can be maintained by depositing a super thin polymer film of ] micron or less and furthermore, as a raw material for use in polymerization a compound of high gas selective permeability can be chosen from a wide range.
In this feature of the present invention, the mean pore diameter of the dense layer is adjusted within a range such that the pores can be closed or plugged by the formation of deposition of the plasma polymerization ' I
-film. If the Jean pore diameter of the dense layer is more -than 0.1 micron, the pores cannot be plugged by the plasma polymerization film. On the other hand, if the mean pore diameter is 0.001 micron or less, the pores can be easily plugged, but gas permeability seriously drops. As a matter of course, the mean pore diameter kick can be plugged by -the plasma polymerization film varies slightly depending on the type of the monomer and the plasma polymerization conditions In the present invention, the mean pore diameter of the dense layer is US micron or less, however, in this feature of the present invention i-t is cJenerally referred that the mean pore diameter is in the range between 0.01 and 0.1 micron.
monomers for use in the plasma polymerization will hereinafter be explained.
It is known that various monomers such as ethylene'and-,ace-tvlene~undergo-pl-asma polymerization in -Jan atmosphere in which a glow discharge is applied. In tile resent invention, it is referred to use compounds hiving a tertiary carbon-containing group (C-5H-C) as a functional grout and organosilane commends. Examples of such tertiary carbon-containing compounds include tert-but~l compounds such as tert--butylamine, pontoon ~:3~6~L
derivatives such as 4-methyl-l-penten~, octanes such as l-octane and isoprene.
Organosilane compounds which can be used include tetramethylsilane~ hexamethylsilane, methyldichlorosilane, and methy.ltrichlorosilaneO More preferred are organosilanecompunds contain gin an unsaturated bond, such as trimethylvinylsilane, dimethylvinylchlorosilane, vinyltrichlorosilane, methylvinyldichlorosilane, meth:Ltrivinylsilane, allyltrimethylsilane~ and ethynyltrimethylsilaneO
A gas-selectively permeable membrane is preferably prepared by depositing a plasma polymerization thin film directly on the dense layer of an asymmetrical pore diameter structure film of the polyetherimide or the polymer mixture continuing the polyetherimidej having a pore diameter range of from 0.001 to 0.1 micron It is required for the raw materiel for use in the preparation of the film to have superior characteristics It is further necessary that the thiclcness of the plasma polymerization thin film, which 20 . controls the permeability of the membrane., should be reduced to the lowest possible thickness The reason for this is as follows.
The characteristics of the raw material]. are evaluated by the gas permeation coefficient thereof:
P = cm3 . cm/cm2 O succumb Hug -18~
J
TV I
which is calculated with the thickness of the raw material as 1 cm. On the other hand, the characters-3 1` e tics of the composite membrane Jo evaluated by the permeation Wright the thickness of the raw material S itself:
Q = cm3/c~2 succumb Hug Hence, the permeation rate of a 1 micron thick membrane is ten times that of a 10 micron thick membrane although their permeation coefficients are the same. Hence, the characteristics required actually are the permeation rate and the thickness of -the membrane.
Lo the present invention, the asymmetrical pore diameter structure film made of the polyether-imide or the polymer mixture containing the polyether-imide Andy further a second polymer, having a rorediameter range as described above is dried and, there-after, a plasma polymerization layer is. deposited ox the . . .
surface of the dense layer in a thickness of 1 micron or less, preferably 0.3 micron or less. For examDlel the pressure of the plasma polymerization chamber it lowered to 5 torn or less, preferably 2 torn or less, a mixed yes of an unpolymerizable gas end a polvmerizable cJas is introduced into -the chamber, and when a high frequency ~23~
glow discharge is applied at a redetermined ought of, eye., from 5 to 500 I preferably about Jo To the polymerizable gas undergoes plasma polymerization, depositing as a thin film on the surface of the dense layer of the asymmetrical pore diameter structure film.
The thickness of the -thin film increases nearly in proportion to-the time of glow discharge or the flow I, rate of the polymerizable gas and, therefore, it-can be : .:
adjusted -to an appropriate value. Furthermore, as-the --output of glow discharge is increased our decreased the thickness of the deposited film increases or decreases. ,,.,:.
These film-forming conditions can be easily optimized by one skilled in the art. In any case it is necessary in the present invention that a defect-free uniform polymerization film be deposited at a thickness as described-above :~,--.,.
One of the~criteri-a-in selecting the polymerize --------able gas is that the plasma polymerization thin film prepared therefrom prevents as much as possible the- ---passage ozone component of a mixed gays tub separate since the thickness of the plasma polymerization thin film is as low as 1 micron and.pre:Eerably 0.3 micron or less. Plasma polymerizable monomers commonly used, such as ethylene and screen, satisfy the criterion as described above...IIowever;:-comnounds-:-containing a -: :
I
tertiary carbon as a functional group as described above are preferred for use in the nresen-'c invention. More preferred are those compounds further containing a double bond. In addition, the organosilane compounds as described above are preferred for use in the present --invention. Of these organosilane compounds, compounds - -containing an unsaturated functional group such as a .-. , double bond or triple bounder more referred.
Plasma polymerization techniques which can be : ..
utilized in the preserlt.invention are disclosed in detail in US Patent 3,84.7,652.
In using an asymmetrical Gore diameter struck Tory film made of a polyetherimide or a polymer' mixture containing said polyetherimide and having a mean pore diameter o-f 0.1 micron or more, it is prefer-red to deposit thereon a thin film of a polymer having .
- high gaspermeability.~.''Silicone''r'ubbers.such;'as.,.olLowe '''' -I
dim ethyl selection are preferred from the viewpoint of gas permeability and heat resistance. In particular TV type and LTV-tvpe silicone rubbers, both being low temperature vulcanization type and of the two-pac!~-reac~...,:. -lion type, are convenient-for:use -in impregnation into. :.. I.
the interior of fine pores in the asymmetrical pore diameter-structure~i-film Orion reactions after the impregnation since they become polymeric compounds .. .
31 ~3~4Ç~i~
undergoing the condensation-and addition-reactions -described below.
-Sue Russ- -I --Swiss- -I ROW (1) I ! I I
-Sue + Hess- -I -Swiss- -I H O (2) I I . I 1 2 1 12 H it I' loquacious_ - (3) They're also convenient in that before the reaction- -they-can reconverted innately viscosity solution ..
with whic'n.the pores of the asymmetrical pore-diameter. ------ ---- ---structure-film of the present invention can be easily -impregnated.
As one technique to increase gas selectivepermeability,~a plasma polymerization thin film can - furth~er--he..dë~o-sited on-the'comp'os'ite'~atèria~~-h2ving-a'-silicone rubber laminated thereto. Another tuitions. :., that where a plasma polymerization thin film is deposited on the asymmetric pore diameter structure film of. the -....
pol.yetherimide I. or the polymer mixture containing the ...
polyetherimide and then the silicone rubber is- -laminated on the plasma-polymerization thin film. --I ..'~. The F.resen-t.,inv.ention .is::described.in-'greater-,--~--c -detail by reference to the following Examples.' I
of E,~P1E
A dope solution was prepared, consisting of 10~
by White of polyetherimide, ULTEM-1000 produced ho - -General Electric Co.), 40% by weight of N-methyl-2-pyrrolidone, and 50% by weight of tetrahydrofuran.ULT~ 1000 has thè.recurring unit shown below and nay à
molecular weight of about 32,000.:
I eye This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a ..... doctor.. nephew The entire-glass~plate was-soaked-in-~ a-;
distilled water at room temperature to coagulate the dope solution. The.thus-formed.film was peeled off, washed with water pharaoh hours, android by blowing air at 45C for 2 hours to prepare about a-90 micron thwack asymmetrical-pore..diameter structure film. : ...
Scanning electron microscopic analysis showed . ...
that thwackers section-of:.the.:film Houdini asymmetrical pore diameter structure.
cue ok ~1~34~6~
The gas permeation characteristics of the film were measured using air as a feed gas. The oxygen permeation rate Q2 was about 3.2xlO 6 cm3/cm sea cm Hug, and the oxygen/nitrogen selectivity a (oxygen permeation rate/nitrogen permeation rate) was about 4 9.
The oxygen permeation rate per centimeter of thickness, i.e., the oxygen permeation coefficient, POX
(calculated from --2) was about 2.9xlO 8 cm3 cm/cm2 sea cm Hug.
A dope solution was prepared, consisting of 20% by weight of the polyetherimide Ultra and 80%
, Jo.
by weight of N-methyl-2--pyrrolidone.
This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a doctor knife. The entire glass plate was soaked in distilled water at room temperature to coagulate the dope solution. The thus-forrned film was peeled off, washed with water for 2 hours, and dried by blowing air at 45C for 2 hours to prepare about a 150 micron thick asymmetrical pore diameter structure film.
The gas permeation characteristics of the film were measured in the same manner as in Example 1 and the results were as follows:
Q2 - 2.0xlO 5 cm3/cm2-sec-cm Hug PO - 3 Ox10-7 cm3-cm/cm2.sec.cm Hug * ~rclcJe Jo - 24 -~L23~
Scanning electron microscopic analysis showed that the cross section of the film had an asymmetrical pore diameter structure as shown in Figure pa and 4b.
A dope solution was prepared, consisting of 16~ by weight of polysulfone (Duel P-170~ produced by U.C.C.), 4% by weight of the polyetherimide, ULTE~I-1000~, 60% by weight of N-methyl-2--~yrrolidone, and 20% by weight of tetrahydrofuran.
Duel Pus the recurring unit shown below and has a molecular weight of about 28,000.
O SHEA
O C~3 This dope solution was flowed over a smooth glass plate in a thickness of 300 microns by means of a doctor knife and was allowed to stand for 2 minutes. At the end of -the time, the entire glass plate was soaked in distilled water at room temperature to coagulate the dope solution. The thus-formed film was peeled off, washed with water for 2 hours, and dried by blowing air 20 at 45C for 2 hours to prepare about a 120 micron thick asymmetrical pore diameter structure film.
jrrc~Je JAR ok -- 2 s ~3g~
It was confirmed by scanning electron micro-scopic analysis that the cross section of -the film had an asymmetrical pore diameter structure.
The gas permeation characteristics of the film were as follows:
Q2 - ~,5xlO 6 cm3/cm2~sec~cm Hug POX - laxly 7 cm3 cm/cm2 succumb Hug , 2.1 Asymmetrical pore diameter structure films were prepared in the same manner as in Example 1 except that dope solutions having the compositions as shown in Table 1 were used.
The thickness and gas permeation characters-tics of each film are shown in Table 2.
It was confirmed by scanning electron micro-scopic analysis that the cross section of the film had .. .. . . . ..
an asymmetrical pore diameter structure.
CO1~1PA~TIVE EXPEL
A dope solution was prepared, consisting of ?~'~ by weight of the polysulfone, Duel P-1700~ and I
by weight of N-methyl-2-pyrrolidone.
This dope solution was flowed over a smooth glass plate in a thickness of 150 microns by means of a doctor knife and, thereafter, dried in an atmosphere of air maintained at 250C for 2 hours to prepare about a 'rouge I
~3~L6~
23 micron thick dense film The specific gravity of the film was Lowe To gas permeation characteristics of the film were as follows:
Q0 - 9 lxlO-8 cm3/cm2-sec~cm Hug P02 -I 2.1xlO 10 cm3~cm/cm~-sec~cm Ho a -O 600 COMPARATIVE EXILES 2 To 4 Dense films were prepared in the same manner lo as in Comparative Example 1 except that dope solutions having the compositions as shown in Table 3 were used_ ;
The thickness Suzuki gravity and gas permeation characteristics of each film are shown in Table 40 lo EXAMPLE 8 on asymmetrical pore diameter structure film was prepared in-the--sam~ manner -as-i~-Example Z. -~~
solution consisting of I by weight of silicone rubber (I 0 2) (an equimolar mixture Of vinyl selection and JO hydrogen selection both having a viscosity of-about 7 r (poise) and 80% by weight of Freon 113 (trifluorotrichlc,r~r~
ethanes produced by Deacon Cage Co., Ltd.) was coated on the asymmetrical pore diameter structure film as prepared above on the dense layer side thereof in a thickness of 150 microns and vulcanized with hot air at 120C for 4 minutes to prepare and composite membrane.
trade Mark 27-~L23~
The gas permeation characteristics of the composite membrane were as follows: :
Q2 = 7~1 X 10 cm3/cm2 O succumb Hug = 2~9 A composite membrane was prepared in the same manner as in Example I This composite membrane was place in a reaction chamber, a a glow discharge was applied at an output of 20 w while introducing trimethylvinylsilane at a . flow rate of OWE cm 8/mln to deposit a plasma polymerization film on the outermost layer of the dense layer side of the composite membrane.
The gas permeation characteristics of the three-layer composite membrane as prepared above were as follows:
.
QUEUE - 8.7 X 10-~ cm3~cm2 . succumb Hug I= 5.8 An asymmetrical pore diameter structure film was prepared in the same manner as in Example 5. A solution consisting of 20% by weight of the silicone rubber (I= 21 which is the same as used in Example 8 and 80% by weight of Freon 113* was coated on the surface of a dense layer of the symmetrical pore diameter structure film in a thickness of 140 microns and vulcanized *Trade Mark -28-~34~
with hot air at 170C for 30 minutes to prepare a composite membrane The gas permeation characteristics of the composite membrane were as phallus:
Q2 0 609xlO 6 m3!cm~cS~ cm Hug Eg~PLE 11 _ _ .
A composite membrane was prepared in the same manner as in example in except that an asymmetrical Gore diameter structure film as repoured it the same manner as in Example 6 was used Thea gas poinciana characteristics of the composite me3nbrane were as follows:
Q0~--9 o 8xlO 6 cm3/cm2-sec cm Hug a .- 2~2 E~'~2~LE 12 A composite membrane was prepared in the same manner as in Example loo This composite membrane was placed i~.a.xeaction chamber, an a glow discharge was- --applied at an output of 20 w for 30 minutes while introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization film on the outermost layer of the dense layer side of the composite membrane The gas permeation characteristics of the three-layer composite membrane as prepared above were as follows:
.
I
Q2 -. l.9X10 6 cm /cm2 sea cm Hug -. 3.5 E~IPLE 13 An asymmetrical none diameter structure film was prepared in the same manner as in Example 2 except that a dope solution consisting of 20% by weight of the polyetherimide, LUTE 1000~, 60% by weight of N-methyl-2-pyrrolidone, and 20% by weight of tetrahydrofuran was used.
The gas permeation characteristics of the asymmetrical pore diameter structure film were as follows:
Q2 - g Oslo 6 cm3/cm2~sec cm Hug -. 1.4 This asymmetrical pore diameter structure film was placed in a reaction chamber, and a glow discharge rJas applied at an output off w for 30 Monticello .:
introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization film on the surface of the dense layer.
The gas permeation characteristics of the composite membrane as prepared above were as follows:
Q2 . 3.1xlO cm3/cm succumb Hug I
Jo I
EXPEL I
An asymmetrical pore diameter structure film was prepared in the same manner as in Example 3. This asymmetrical pore diameter structure film was placed in a reaction chamber, and a glow discharge was applied at an output of 20 w for 30 minutes while introducing trimethylvinylsilane at a flow rate of 0.7 cm3/min to deposit a plasma polymerization filmlon the dense layer of the asymmetrical pore diameter structure film.
The gas permeation characteristics of tile composite membrane as prepared above were as follows:
Q2 -. 2.6xlO 6 cm3/cm2~sec~cm Hug -, 3.7 . _ _ _ _ . _ .. , .. _ _ , . _ ., _ __ .. _ _ _ _ . ,__ . _. , _ __ _ __ _ _ _, _, _ _, .. , _ _ _. _. _ ._ _ _ _, ... -- I_ -- , _ _ .... , -- -- . _ _ _ = .. ---- ... -- : -- -- -- -- --. _ .. -- --. -- .. --' ' : , = ---- -- -- , -- . _ 1.. --': ' 123~
Dope Solution Polymer I Polymer II Solvent Example Polymer wit% Polymer wit% Solvent wit%
4 A 10 *3 *5 *2 10 C 4 " "
6 B 10 C 10 " "
Note:
*1 Polysulfone: Duel P-1700 (produced by U.C.C.) *2 Aromatic Polyester: U Polymer U-100 (produced by Unitika Co., Ltd.) *3 Polyetherimide: ULTE~1-1000 (produced Brie General Electric Co.) *4 polycarbonate Up iron S-2000 (pr^rluced by '' = 'Mits'ùbishi'Gas'Chemi'cà'l'Co.','=L'td.)' -~"-~"'=` ~'~"~`''~ -~~~'~'-~
*5 N-methyl-2-pyrrolidone U Polymer U-lOO~has the recurring unit shown below and has a molecular weigh-t of about 28,000.
O O OH
okay 4 c-o 4 c SHEA
Jro.cJe on ' I
. Up iron S-2000 has the recurring unit shown below and has a molecular weight of about 32,000.
oily- jCI~
SHEA O
physical Properties of Films _.
. Gas Permeation Characteristics Thick-Exampleness Q2 POX
(~) (cm3/cm2~ (cm3-cm/cm2 (Q02/QN2) sec~cmHg) sec~cmHg) 4 160 2.0 x 10 4 3.2 x 10 6 1.0 160 4.8x 10 5 7.7 x 10-7 1.3 6 170 6.2X 10 5 1.1 x 10-6 1.1 10 7 200 8.2 x 10 1.6 x 10 1.0 I.
Dope Solution Comparative Polymer Solvent Example Polymer wit% Solvent wit%
.. , _ * The same polymer designations in above Table 1 are used.
*-rr~J~ ok - 33 -~3~L6~l Physical Properties of films Canopy- Gas Permeation Characteristics alive Thick- Specific x e news Gravity Q2 P02 (~) (cm3/cm2 (cm3 cm/cm2 (Q2/Q~2) sec-cmHg) sea cmHg) 1 23 1.24 g.lx owe 2.1xlO 10 6.0 2 Lo 1.21 2.0 x 10 7 3,0x 10 10 5.2 3 14 1.29 3.3x 10 I X 107.6 4 15 1.20 6.8 X 10-8 1.0 X 10 10 5,3 The asymmetrical pore diameter structure films obtained in the resonate invention are superior in heat or resistance and I suitable for use in the isolation of argon from air, for the concentration of oxygen, for the concentration or hydrogen in Tony gas and so worth.
Wealth invention.has.been,described:in. I: ,..
detail and with reference to specific embodiments lo thereof, it will be apparent to one skilled in the art that various changes and medications can be made '' therein without departing prom the spirit and scope thereof.
6 B 10 C 10 " "
Note:
*1 Polysulfone: Duel P-1700 (produced by U.C.C.) *2 Aromatic Polyester: U Polymer U-100 (produced by Unitika Co., Ltd.) *3 Polyetherimide: ULTE~1-1000 (produced Brie General Electric Co.) *4 polycarbonate Up iron S-2000 (pr^rluced by '' = 'Mits'ùbishi'Gas'Chemi'cà'l'Co.','=L'td.)' -~"-~"'=` ~'~"~`''~ -~~~'~'-~
*5 N-methyl-2-pyrrolidone U Polymer U-lOO~has the recurring unit shown below and has a molecular weigh-t of about 28,000.
O O OH
okay 4 c-o 4 c SHEA
Jro.cJe on ' I
. Up iron S-2000 has the recurring unit shown below and has a molecular weight of about 32,000.
oily- jCI~
SHEA O
physical Properties of Films _.
. Gas Permeation Characteristics Thick-Exampleness Q2 POX
(~) (cm3/cm2~ (cm3-cm/cm2 (Q02/QN2) sec~cmHg) sec~cmHg) 4 160 2.0 x 10 4 3.2 x 10 6 1.0 160 4.8x 10 5 7.7 x 10-7 1.3 6 170 6.2X 10 5 1.1 x 10-6 1.1 10 7 200 8.2 x 10 1.6 x 10 1.0 I.
Dope Solution Comparative Polymer Solvent Example Polymer wit% Solvent wit%
.. , _ * The same polymer designations in above Table 1 are used.
*-rr~J~ ok - 33 -~3~L6~l Physical Properties of films Canopy- Gas Permeation Characteristics alive Thick- Specific x e news Gravity Q2 P02 (~) (cm3/cm2 (cm3 cm/cm2 (Q2/Q~2) sec-cmHg) sea cmHg) 1 23 1.24 g.lx owe 2.1xlO 10 6.0 2 Lo 1.21 2.0 x 10 7 3,0x 10 10 5.2 3 14 1.29 3.3x 10 I X 107.6 4 15 1.20 6.8 X 10-8 1.0 X 10 10 5,3 The asymmetrical pore diameter structure films obtained in the resonate invention are superior in heat or resistance and I suitable for use in the isolation of argon from air, for the concentration of oxygen, for the concentration or hydrogen in Tony gas and so worth.
Wealth invention.has.been,described:in. I: ,..
detail and with reference to specific embodiments lo thereof, it will be apparent to one skilled in the art that various changes and medications can be made '' therein without departing prom the spirit and scope thereof.
Claims (11)
1. A gas-selectively permeable membrane comprising an asymmetrical pore diameter structure film made of an polyetherimide having the recurring unit represented by formula (A) or a mixture of said polyetherimide and at least one polymer having the recurring unit represented by formula (B), wherein the mean pore diameter of a dense layer located on one side of the asymmetrical pore diameter structure film is 0.5 micron or less and the mean thickness of the dense layer is 10 microns or less:
wherein x is a natural number including zero, Q is
wherein x is a natural number including zero, Q is
2. The gas-selectively permeable membrane as claimed in claim 1, wherein at least one thin polymer film is further laminated on the dense layer of the asymmetrical pore diameter structure film.
3. The gas-selectively permeable membrane as claimed in claim 2, wherein at least one thin polymer film laminated on the dense layer of the asymmetrical pore diameter structure film is a thin polymer layer comprised of a silicon rubber.
4. The gas-selectively permeable membrane as claimed in claim 2, wherein at least one thin polymer film laminated on the dense layer of the asymmetrical pore diameter structure film is a plasma polymerization thin film formed by glow discharge.
5. A method of forming a gas-selectively permeable membrane which comprises combining a solution containing an polyetherimide having the recurring unit represented by formula (A) or a mixture of said polyetherimide and at least one polymer having the recurring unit represented by formula (B), with a solvent, applying the resultant mixture to a flat surface to form a thin film,
5. A method of forming a gas-selectively permeable membrane which comprises combining a solution containing an polyetherimide having the recurring unit represented by formula (A) or a mixture of said polyetherimide and at least one polymer having the recurring unit represented by formula (B), with a solvent, applying the resultant mixture to a flat surface to form a thin film,
Claim 5 continued bringing the thus-formed film into contact with a coagulating agent to remove the solvent and then drying the film to form an asymmetrical pore diameter structure film having a dense layer on one side thereof, wherein (A) & (B) are defined as follows:
wherein x is a natural number including zero,Q is 6. A method of forming a gas-selectively permeable membrane, which comprises combining a solution containing an polyetherimide having the recurring unit represented by formular (A) or a mixture of said polyethermide and at least
wherein x is a natural number including zero,Q is 6. A method of forming a gas-selectively permeable membrane, which comprises combining a solution containing an polyetherimide having the recurring unit represented by formular (A) or a mixture of said polyethermide and at least
Claim 6 continued one polymer having the recurring unit represented by formular (B), with a solvent, extruding the resultant mixture through a tubular nozzle to form a film, bringing the thus-formed film into contact with a co-agulating agent to remove the solvent, and then drying the film to form an asymmetrical pore diameter structure film having a dense layer on one side thereof, wherein (A) and (B) are defined as follows:
wherein x is a natural number including zero,Q is
wherein x is a natural number including zero,Q is
7. The method as claimed in Claim 5 or 6, wherein the solvent is N-methyl-2-pyrrolidone, N-formylpiperidine, 1-formylmorpholine, tetrahydrofuran, or a mixture comprising two or more thereof.
8. The method as claimed in claim 5, wherein a polymer solution is coated on the dense layer of the asymmetrical pore diameter structure film to form a thin polymer film thereon, and then dried to thereby laminate said polymer thin film onto said dense layer of said asymmetrical pore diameter structure film.
9. The method as claimed in claim 6, wherein a polymer solution is coated on the dense layer of the asymmetrical pore diameter structure film to form a thin polymer film thereon, and then dried to thereby laminate said polymer thin film onto said dense layer of said asymmetrical pore diameter structure film.
10. The method as claimed in claim 5 or 6, further comprising the subsequent step of applying a glow discharge while supplying a polymerizable monomer in an atmosphere of 0.5 torr or less to deposit a plasma polymerization thin film on the dense layer of the asyentrical pore diameter structure film.
11. The method as claimed in claim 8 or 9 further comprising the subsequent step of applying a glow discharge while supplying a polymerizable monomer in an atmosphere of 0.5 torr or less to deposit a plasma polymerization thin film on the polymer thin film previously laminated to the dense layer of the asymmetrical pore diameter structure film.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22536482A JPS59115738A (en) | 1982-12-21 | 1982-12-21 | Selective gas-permeable membrane and its manufacture |
| JP225364/82 | 1982-12-21 | ||
| JP160283A JPS59127603A (en) | 1983-01-08 | 1983-01-08 | Gas permselective membrane and preparation thereof |
| JP1602/83 | 1983-01-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1234461A true CA1234461A (en) | 1988-03-29 |
Family
ID=26334854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443877A Expired CA1234461A (en) | 1982-12-21 | 1983-12-21 | Selectively permeable asymmetric membrane of polyetherimide |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4832713A (en) |
| EP (1) | EP0113574B1 (en) |
| CA (1) | CA1234461A (en) |
| DE (1) | DE3379260D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0489693A1 (en) | 1990-12-03 | 1992-06-10 | Aligena Ag | Charged asymmetric mosaic membranes |
Families Citing this family (32)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6094106A (en) * | 1983-10-27 | 1985-05-27 | Nitto Electric Ind Co Ltd | Manufacture of compound membrane |
| DE3420373C2 (en) * | 1984-06-01 | 1986-09-18 | Gkss - Forschungszentrum Geesthacht Gmbh, 2054 Geesthacht | Process for the production of an integrally asymmetrical membrane for the separation of gases |
| US4705540A (en) * | 1986-04-17 | 1987-11-10 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| GB8617263D0 (en) * | 1986-07-15 | 1986-08-20 | British Petroleum Co Plc | Separation media |
| US4717394A (en) * | 1986-10-27 | 1988-01-05 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| US4717393A (en) * | 1986-10-27 | 1988-01-05 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| US4963165A (en) * | 1987-04-27 | 1990-10-16 | Membrane Technology & Research, Inc. | Composite membrane, method of preparation and use |
| DE3716916A1 (en) * | 1987-05-20 | 1988-12-01 | Geesthacht Gkss Forschung | METHOD FOR PRODUCING AN INTEGRAL ASYMMETRICAL MEMBRANE |
| FR2623101A1 (en) * | 1987-11-12 | 1989-05-19 | Rhone Poulenc Rech | Composite membrane usable for removing water vapour from air or carbon dioxide |
| GB8805992D0 (en) * | 1988-03-14 | 1988-04-13 | Shell Int Research | Process for preparing non-porous membrane layers |
| US4948400A (en) * | 1988-06-30 | 1990-08-14 | Nippon Steel Chemical Co., Ltd. | Separation membranes and process for preparing the same |
| US4932983A (en) * | 1989-06-01 | 1990-06-12 | E. I. Du Pont De Nemours And Company | Copolyimide gas separation membranes derived from substituted methylene dianilines and unsubstituted diamines |
| US4932982A (en) * | 1989-06-01 | 1990-06-12 | E. I. Du Pont De Nemours And Company | Copolyimide gas separation membranes derived from substituted phenylene diamines and substituted methylene dianilines |
| US4981497A (en) * | 1989-06-01 | 1991-01-01 | E. I. Du Pont De Nemours And Company | Amine-modified polyimide membranes |
| US5026823A (en) * | 1989-09-12 | 1991-06-25 | The Dow Chemical Company | Novel alicyclic polyimides and a process for making the same |
| US4988371A (en) * | 1989-09-12 | 1991-01-29 | The Dow Chemical Company | Novel alicyclic polyimide gas separation membranes |
| US5178649A (en) * | 1989-12-21 | 1993-01-12 | The Dow Chemical Company | Poly(arylene ether ketimine) gas separation membranes |
| US5096586A (en) * | 1990-08-28 | 1992-03-17 | Regents Of The University Of California | Membranes having selective permeability |
| US5248427A (en) * | 1990-09-15 | 1993-09-28 | Basf Aktiengesellschaft | Removal of water from mixtures with alcohols and/or carboxylic acids and/or carboxylic esters |
| DE4142502A1 (en) * | 1991-12-21 | 1993-06-24 | Solvay Umweltchemie Gmbh | BUBBLE-FREE HYDROGEN SUBSTANCE IN WAESSED LIQUIDS |
| US5266100A (en) * | 1992-09-02 | 1993-11-30 | E. I. Du Pont De Nemours And Company | Alkyl substituted polyimide, polyamide and polyamide-imide gas separation membranes |
| US5248319A (en) * | 1992-09-02 | 1993-09-28 | E. I. Du Pont De Nemours And Company | Gas separation membranes made from blends of aromatic polyamide, polymide or polyamide-imide polymers |
| EP0648812B1 (en) * | 1993-10-19 | 2003-09-10 | L'air Liquide, S.A. à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procédés Georges Claude | Blends of polyethersulfones with aromatic polyimides, polyamides or polyamide-imides and gas separation membranes made therefrom |
| US5443728A (en) * | 1994-04-28 | 1995-08-22 | Praxair Technology, Inc. | Method of preparing membranes from blends of polyetherimide and polyimide polymers |
| US5702503A (en) * | 1994-06-03 | 1997-12-30 | Uop | Composite gas separation membranes and making thereof |
| US5733657A (en) * | 1994-10-11 | 1998-03-31 | Praxair Technology, Inc. | Method of preparing membranes from blends of polymers |
| GR1002482B (en) * | 1995-12-07 | 1996-12-03 | New polymer membranes prepared from polysulfone and polyimide blends for the separation of industrial gas mixtures. | |
| ES2155737B1 (en) * | 1998-02-16 | 2001-12-01 | Consejo Superior Investigacion | PROCEDURE FOR THE PREPARATION OF CARBON MICROPOROUS CARBON MEMBRANES. |
| DE19901378A1 (en) * | 1999-01-15 | 2000-07-20 | Fraunhofer Ges Forschung | Process for producing a polymer membrane, in particular a polymer electrolyte membrane for methanol fuel cells, and such a membrane |
| DE60127734T2 (en) * | 2000-01-19 | 2007-12-27 | Ube Industries, Ltd., Ube | Gas separation membrane and its use |
| US20060011063A1 (en) * | 2004-07-16 | 2006-01-19 | Honeywell International Inc. | High temperature gas separation membrane suitable for OBIGGS applications |
| JP2015073980A (en) * | 2013-10-11 | 2015-04-20 | 富士フイルム株式会社 | Gas separation membrane and gas separation membrane module |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3615024A (en) * | 1968-08-26 | 1971-10-26 | Amicon Corp | High flow membrane |
| NL174020C (en) * | 1973-09-07 | 1984-04-16 | Sumitomo Chemical Co | METHOD FOR MANUFACTURING A MEMBRANE FOR SEPARATING SUBSTANCES, AND THE MANUFACTURED MEMBRANE |
| US4071590A (en) * | 1974-11-02 | 1978-01-31 | Forschungsinstitute Bergof Gmbh | Composite asymmetrical membranes |
| US4156597A (en) * | 1977-09-23 | 1979-05-29 | General Electric Company | Ultrathin polyetherimide membrane and gas separation process |
| US4293670A (en) * | 1979-12-26 | 1981-10-06 | Union Carbide Corporation | Blends of poly(aryl ether) resins and polyetherimide resins |
-
1983
- 1983-12-21 EP EP83307788A patent/EP0113574B1/en not_active Expired
- 1983-12-21 DE DE8383307788T patent/DE3379260D1/en not_active Expired
- 1983-12-21 CA CA000443877A patent/CA1234461A/en not_active Expired
-
1987
- 1987-04-27 US US07/042,554 patent/US4832713A/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0489693A1 (en) | 1990-12-03 | 1992-06-10 | Aligena Ag | Charged asymmetric mosaic membranes |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0113574B1 (en) | 1989-03-01 |
| US4832713A (en) | 1989-05-23 |
| EP0113574A2 (en) | 1984-07-18 |
| DE3379260D1 (en) | 1989-04-06 |
| EP0113574A3 (en) | 1986-11-20 |
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