JPS6279832A - Composite film for gas separation - Google Patents

Abstract

PURPOSE:To obtain the titled film having improved properties of separation, permeability and durability by providing a layer A made of a high polymer and having a gas permeability, and a layer B made of a polyarylene oxide contg. a silicon atom on a porous substrating body. CONSTITUTION:The layer A made of the high polymer and having the gas permeability and the layer B made of the polyarylene oxide and contg. the silicon atom are provided on the porous substrating body to form the composite film for the gas separation. The material constituting the porous substrating body contains a polysulfonic acid or a polyolefins, etc. Size of fine pores lying on the surface of the substrating body is preferably 10-2,000Angstrom . The oxygen permeability coefficient PO2 of the layer A is preferably 1X10<-8>(cm<2>.cm/ cm<2>.sec.cm Hg). The layer B is made of the polyarylene oxide contg. the organosilyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite membrane for gas separation that is used to separate mixed gases and has good permselectivity and gas permeability.

[Prior Art] Recently, separation technology using membranes has made remarkable progress, and has been put to practical use on an industrial scale in fields such as seawater desalination, ultrapure water production, and wastewater treatment. Further, in the separation of gases using membranes, practical application of hydrogen, hydrocarbons, carbon dioxide, etc. is progressing.

One example of the application of such membranes to gas separation is the production of pixel-enriched air. Oxygen-enriched air is required for respiratory purposes in the medical field, and for combustion systems in the industrial field, and has a wide range of applications. Normal combustion systems (boilers, for example) use air in addition to fuel, but if oxygen-enriched air, which has an increased oxygen concentration in the air, is supplied to the combustion system instead of this air, fuel efficiency and combustion temperature can be improved. It is possible to achieve an improvement in fuel consumption and a reduction in the amount of combustion exhaust gas, and is expected to be effective in terms of both energy conservation and pollution prevention.

Despite these expectations, gas separation using polymer membranes has hardly been put into practical use on an industrial scale.
Practical use is only beginning to take shape in a few limited fields, such as hydrogen separation.

One of the reasons why the practical application of gas separation using polymer membranes has not progressed is that there has been a delay in the development of membrane materials that have excellent gas permeability and gas separation properties and can be easily made into thin films. . In general, gas permeability and gas separation properties of polymer membranes tend to be contradictory, and in order to overcome this, various methods have been investigated to form composite membranes.

The gas permeation rate (Q) of polymer membranes used for the production of oxygen-enriched air and other gas separations is generally calculated using the following formula (%), where P is the permeability coefficient (-cm/aK sec cmH
g), △p is the partial pressure difference of the permeate gas on both sides of the membrane (cmHg
), A is the membrane area (cJ), and d is the membrane thickness (cm). The gas separation property of a thin polymer film is necessarily unique to the polymer membrane and does not depend on the film thickness. On the other hand, gas permeability is improved by making the membrane thinner, as required by the above equation, so how to make the membrane material with gas separation properties thinner as a homogeneous membrane with no defects is an important factor in making composite membranes. This is the point.

From this point of view, composite membranes for gas separation with various configurations have been devised. For example, in U.S. Pat. No. 3,874,986@ specification, for the role of adhesion and cushioning between a thin film layer made of polyphenylene oxide and organoborisiloxane → nanoboricarbonate copolymer and a porous support layer,
A laminated composite membrane having an intermediate layer made of organopolysiloxy-1 non-polycarbonate-1 to copolymer has been proposed. Further, in US Pat. No. 3,980,456, a thin film layer is further provided on the laminated composite film to cover pinholes caused by inclusion of fine particles.

However, such laminated composite membranes use a thin film layer made of two types of polymers as the separation active layer, and due to phase separation of these polymers, membrane performance (separability and permeability) or durability may not necessarily be sufficient. I can not say. Also, JP-A-5
Publication No. 7-4203 proposes a composite membrane in which the surface of a membrane using poly-4-methylpentene is coated with a substance that does not have membrane-forming ability. Although the improvement is achieved, it is thought that there is a problem with durability because there is a layer of a substance that does not have film-forming ability on the film surface.

[Problems to be Solved by the Invention] The present invention provides a composite membrane for gas separation that does not have the drawbacks of the conventional examples as described above, that is, a gas separation membrane that has excellent separation performance, permeability, and durability. The purpose is to provide a composite membrane for

[Means for solving problems] In order to achieve the above object, the present invention consists of the following configuration.

``A composite membrane for gas separation, characterized in that a layer (A) made of a polymer having gas permeability and a layer (B) made of polyarylene oxide containing silicon atoms are provided on a porous support. ” The porous support in the present invention has the size of the micropores present on the surface of the porous support to effectively express the separation characteristics of the laminated thin films and to obtain a sufficient amount of gas permeation.
0 to 10,000 people, preferably 10 to 2,000 people. Porous supports include extraction methods, layer separation methods, stretching methods,
Organic porous supports or inorganic porous supports made by various methods such as calcination can be used. For organic porous supports, homopolymers such as polysulfones, celluloses, polyolefins, polyesters, polyamides, polyimides, etc. or blends of these polymers are usually used, but they are not particularly limited to these. It's not something you can do. As for the shape of the porous support, in addition to a flat membrane shape, a hollow fiber shape, a tube shape, etc. can be used.

The polymer constituting the layer (8) made of a polymer having gas permeability means, for example, when using the oxygen permeability coefficient PO2 as a measure of permeability, the polymer has a PO2 of at least 5X10-9.
1aK-cm/crK・sec・cmHq] or more, preferably 10−8 [ci-Cm/cJ・sec・CmH
Q] It has the following characteristics. Examples of polymers whose oxygen permeability coefficient satisfies the above range include polyorganosiloxanes such as polydimethylsiloxane, silphenylene-siloxane copolymers, polycarbonate-polysilokinane copolymers, polysulfone-polysilokinane copolymers, Polyorganosiloxane copolymers such as polystyrene-polysiloxane copolymers, substituted polyacetylenes such as poly(↑ert-butylacetylene), poly(1-dimethylsilylpropyne), poly(di-tert-butyl fumarate) ), and polyorganophosphazenes such as poly(bisethoxyphosph7zene), but are not limited to these as long as the carbon permeability coefficient substantially satisfies the above range.

In addition, the thickness of the layer (A) made of a gas-permeable polymer is generally 0.001.
A suitable range is 01 to 3μ, preferably 00O3 to 0.5μ.

Examples of the polymer constituting the layer (B) made of polyarylene oxide containing silicon atoms include polyarylene oxide having an organosilyl group, polyarylene oxide-organosiloxane copolymer, and polyarylene oxide-organosyl alkylene copolymer. Examples include merging. When the polymer is a copolymer of polyarylene oxide and a silicon-containing polymer as in the latter two examples, examples of the copolymer include random copolymers, block copolymers, graft copolymers, bendane 1- Although it may be in any state such as a type copolymer, a pendant type copolymer is more preferable because the membrane performance is particularly good. Further, the polymer constituting the layer (B) may be partially crosslinked.

The basic structure of the polyarylene oxide moiety contained in the polymer constituting the layer (B) made of polyarylene oxide containing silicon atoms is represented by the general formula. Here, m is an integer of 1 to 3, and n is an integer of 25 or more, preferably 50 or more.

In addition, in the aromatic ring contained in the polymer main chain, it is preferable that the connection with the oxygen atom in the general formula and the connection with the oxygen atom in the adjacent repeating unit be at the para position, but some connections may be made at other positions. There is no problem even if it is. R may be the same,
They may be different from each other and are selected from alkyl groups, substituted alkyl groups, phenyl groups, substituted phenyl groups, halogen atoms, alkoxy groups, alkenyl groups, alkynyl groups, amino groups, and the like. The number of carbon atoms contained in the substituent R is preferably 15 or less, more preferably 8 or less.

The polyarylene oxide represented by the above general formula contains at least one hydrogen atom or herogen atom on the aromatic ring in the main chain, or at least one hydrogen atom or hydrogen atom on the aromatic ring in the main chain, or at least one hydrogen atom or hydrogen atom on the aromatic ring in the main chain. It is necessary that one or more hydrogen atoms, halogen atoms, etc. are retained.

In particular, when R is an alkyl group, it is necessary that at least one hydrogen is contained on the carbon atom adjacent to the main chain aromatic ring. Further, the repeating units contained in the polymer may be single or different.

The silicon atom-containing polyarylene oxide is such that all or a portion of the hydrogen atoms and/or halogen atoms on the aromatic carbon or aliphatic carbon contained in the general formula of the polyarylene oxide are organosilyl groups or organosiloxanes. Structures substituted with chains, organosylalkylene chains, and structures in which organosilyl groups, organosilokynan chains, or organosylalkylene chains are added to all or part of the unsaturated bonds contained in the above general formula. refers to something.

These silicon atom-containing polyarylene oxides are disclosed in, for example, Japanese Patent Application No. 49132/1982, Japanese Patent Application No. 1983-
It can be synthesized by the method described in No. 54271 and the like.

Furthermore, the layer (B) made of polyarylene oxide containing silicon atoms may partially contain the following polymer as a second component. The second component includes various olefin polymers such as poly(4-methylpentene), poly(vinyl-1-helimethylsilane), polystyrene, poly(fumarushun-di-tert-butyl), poly(2,6 -Simethyl-P-phenylene oxide)
aromatic polyethers such as polydimethylsiloxane, polyorganosiloxanes such as polymethylphenylsiloxane, polyorganosiloxanes such as silnoenylene-siloxane copolymers, polycarbonate-polysiloxane copolymers, polysulfone-polysiloxane copolymers, etc. Examples include copolymers, substituted polyacetylenes such as poly(tert-butylacetylene) and poly(trimethylsilylpropyne), and polyorganof-t-sphazenes such as poly(bis-1-xif-4 sphazenes).

The thickness of the layer (B) made of polyarylene oxide containing silicon atoms is generally 0.00000.000000000000000000000000,000. 01-1μ, preferably 0.01-0
．． A range of 3μ is appropriate.

The silicon atom-containing polyarylene oxide used in the present invention differs depending on its composition, but in -II, an aromatic solvent such as benzene, 1 to toluene, xylene, etc.
cyclohexane, aliphatic hydrocarbon solvents such as n-hexane, chlorobenzene, chloroform, dichloromethane,
It is soluble in single or mixed solvents such as halogenated hydrocarbon solvents such as trifluoro-1 to dichloroethane, ether solvents such as tetrahydrofuran and dioxane, and can be used to form films or thin films using solutions using these solvents. It is possible to

A layer (A) made of a polymer having gas permeability and a layer (A) made of a polyarylene oxide containing silicon atoms.
The lamination method of B) includes a method of laminating a thin polymer film obtained by casting a dilute solution of the polymer onto the water surface and evaporating the solvent by various methods, a dipping method, a roll coating method, and a spray method. Examples include coating methods such as coating methods, in situ polymerization, and interfacial polymerization. In addition, the order of lamination is as follows:
(A) layer-(B) layer-porous support, (B) layer-(A)
A suitable channel configuration is layer-porous support, (A) layer-(B) layer-(A) layer-porous support.

The membrane of the present invention has excellent separation and permeation properties for gas mixtures, and can be used for various gases such as hydrogen, oxygen, nitrogen, carbon dioxide, hydrocarbons, carbon oxides, hydrogen sulfide, argon, helium, and sulfur dioxide. Can be used for separation and concentration. Furthermore, combustion efficiency can be improved by incorporating the membrane of the present invention into an oxygen enrichment system for producing air-rich air from air and using it in combustion systems such as engines, boilers, and heating appliances. Furthermore, the oxygen enrichment system can be used in medical applications such as treatment devices for respiratory diseases and premature infants, artificial lungs, artificial gills, and gas recovery applications such as nitrogen-enriched air production.

[Example] The invention is illustrated in greater detail by the following examples.

The oxygen permeability coefficient PO2 and nitrogen permeability coefficient PN2 of the films in Examples were measured at 25°C using a gas permeability measuring device manufactured by Yanagimoto Seisakusho Co., Ltd. The gas permeation rate Q in the composite membrane was measured using Precision Membrane Flow ff1l manufactured by Estech Co., Ltd.

Production Example 1 (1) Preparation of Polymer (1) 12 g of poly(2,6-dimethyl-1,4-phenylene oxide) was dissolved in 650 ml of anhydrous tetrahydrofuran, and N, N, N', N'- Te! 19 ml of 19 ml of methylethylenediamine and a solution of n-butyllithium in n-hexane (1,7M>67 ml) were added and stirred for 40 minutes. 21 ml of 1 to 1-lymethylchlorosilane were added to the reaction solution.
was added and continued to be roughly stirred for 75 minutes. After concentrating the reaction solution, it was poured into about 1.5% methanol and the polymer was recovered by filtration.

After purifying the polymer again by methanol reprecipitation, it was dried under reduced pressure to obtain a product of 14.2 CJ).

The infrared absorption spectrum of this polymer is 1250
An absorption derived from the trimethylsilyl group is seen at cm',
In general nuclear magnetic resonance analysis, it was confirmed that trimethylsilyl groups were introduced into about 34% of the polyphenylene oxide repeating units.

After casting a 5% chloroform solution of this polymer on a glass plate and drying it at room temperature for 3 days, the oxygen permeability coefficient PO2 of the film was 2.9X10-9 (al-cm/al
-sec -cmHQ'), nitrogen permeability coefficient PN2 is 7
．． 2X10 (ci-cm/1-sec-cmH
Q>, and the separation coefficient α (= PO2/P N 2.
) was 4.0.

Example 1 Polydimethylsiloquiline with silanol groups at both ends (
9.5 g (number average molecular weight approximately 50,000), 0.4 CJ of tetrakis(2-propanone oxime) silane, and 1 to 0.1 g of dibutyltin diacetate were dissolved in cyclohexane to obtain a solid content of 0.
．． Prepare a 5% solution. A portion of this dilute solution was coated onto a polysulfone porous support and 130'
After heating and drying at C for 1 minute, the mixture was dried at room temperature for 1 hour to obtain a crosslinked siloquiline composite membrane. The thickness of the polydimethylsiloquiline layer of this composite membrane was approximately 0.1 μm. The @ elementary passing rate QO2 of the composite membrane is 8.0 [m'/m2-hr-at
m ], and the separation coefficient α (=QO2/QN 2 )
G, t2.0.

0.5 g of the polymer synthesized in Production Example 1 (1>[polymer having a trimethylsilyl group]) was uniformly dissolved in 16 CI of chloroform. A portion of this polymer solution was cast onto the water surface, and the solvent was allowed to cool at room temperature. A thin film was obtained by volatilization.

This thin film was laminated by a suction method on the crosslinked silokinane composite film prepared as described above to obtain a laminated composite film. The permeation rates of various gases through this laminated composite membrane are shown in Table 1, and it was possible to separate various gases. It was also confirmed that the oxygen enrichment performance of this laminated composite membrane was good in terms of both separation and permeability.

Comparative Example 1] Poly(4-methylpentene) was used instead of the polymer (1) used in Example 1 to create a laminated composite membrane.

MWA was obtained by casting a 2% by weight solution of poly(4-methylpentene) in cyclohexane onto the water surface and volatilizing the solvent at room temperature.

This thin film was laminated on the crosslinked siloquiline composite membrane prepared in Example 1 by a suction method to obtain a laminated composite membrane. The oxygen permeation rate QO2 of this laminated composite membrane is 1.8 [m'/m' -h
r - atm ], the nitrogen permeation rate QN2 is 0°6 [T
r1″/m2.−hr-atm], separation coefficient α(
=Q02/QN2) was 3.0, and the laminated composite membrane of Example 1 did not exhibit any good performance.

Table 1 [Effects of the Invention] The composite membrane for gas separation of the present invention has excellent gas permeability and permselectivity, and has good membrane strength and durability.The membrane of the present invention enables effective and economical gas separation. became possible.

Claims (3)

[Claims] (1) A composite membrane for gas separation characterized in that a layer (A) made of a polymer having gas permeability and a layer (B) made of polyarylene oxide containing silicon atoms are provided on a porous support. . (2) The oxygen permeability coefficient PO_2 of the layer (A) made of a gas-permeable polymer is 1×10^-^8 [cm^3.
The composite membrane for gas separation according to claim 1, characterized in that the composite membrane has a property of not less than cm/cm^2·sec·cmHg]. (3) The layer (B) made of polyarylene oxide containing silicon atoms is selected from polyarylene oxide having an organosilyl group, polyarylene oxide-organosiloxane copolymer, and polyarylene oxide-organosyl alkylene copolymer. The composite membrane for gas separation according to claim (1), characterized in that it is made of one or more types of polymers.