JPS6118421A - Gas separating membrane - Google Patents

Abstract

PURPOSE:To obtain a gas separating membrane which has excellent permeability and is excellent in coefficient of separation of oxygen and nitrogen and is easy in thin filming by using a copolymer of substituted acetylene polymer and polyorganosiloxane. CONSTITUTION:A membrane is formed by the copolymer of a substituted acetylene polymer having the repeating unit shown by the formula and polyoroganosiloxane having active hydrogen in the side chain or the terminal. As the substituted acetylene, 1-trimethyl-1-propyne can be used. The numerical average mol. wt. is 10,000 and the proportion of weight of both the components of copolymer is (90:10)-(10:90) and the proportion of acetylene part and active hydrogen group (SiH group) is 1:(1-0.01). The filming is performed so as to obtain 0.01-100mu film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas separation membrane. More specifically, the present invention relates to a gas separation membrane having good gas permeability and selective permeability.

[Conventional technology]

BACKGROUND ART In recent years, methods using thin polymer films have been attracting attention as a means for separating and is-condensing specific gases (oxygen, nitrogen, etc.) from mixed gases (air, etc.).

Conventionally, polydimethylsiloxane and polydimethylsiloxane-polycarbonate block copolymers have been known as such membranes.

[Problem that the invention seeks to solve]

The present inventors have previously discovered that 1-monoalkyldimethylsilylpropyne polymer is an excellent material with excellent gas permeability (Japanese Patent Application No. 58-29786
As a result of the above-mentioned intensive studies to obtain a separation membrane that does not change over time, the present invention was achieved.

[Means to solve problems]

That is, the present invention provides a substituted acetylene polymer having a repeating unit represented by the general formula (wherein R is a linear or branched alkyl group or a Si-containing alkyl group of 01'' to 2); It is a gas separation device characterized by being formed from a copolymer with a polyorganosiloxane having active hydrogen at the chain or end.

In the general formula (1), the C1-12 linear alkyl group of R is methyl, ethyl, propyl, and butyl.

Pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl groups, etc.; C1-12 branched alkyl groups include isobutyl group, tert-butyl group, etc.;
Examples of the Si-containing alkyl group include trimethylsilylmethyl group and ``trimethylsilylethyl group. Examples of monomers used to obtain a polymer having the unit represented by general formula (1) as a repeating unit include 1-trimethylsilylpropylene. Pin, 1-mono-n-propyldimethylsilylpropyne, 1-mono-n-hexyldimethylsilylpropyne, 1-()limethylsilyl)methyldimethyl-1-propyne, 1(trimethylsilyl)ethyldimethylsilyl-1- Examples include propyne and mixtures of two or more of these.Among these, preferred are 1-
It is trimethylsilylpropyne.

1-Trimethylsilyl-1-propyne is a commercially available monomer (product of Betrak Co., Ltd. in the United States, product T of SP Development Department of Chisso Corporation).
8728) can be used.

The polymer is niobium (Nb), which is a Group V transition metal.

Catalysts based on compounds containing tantalum (Ta) halides (e.g. NbCe5, TaCJ's,
NbBr5, TaBr5) and in the presence of solvent (
Aromatic hydrocarbons such as benzene, toluene, xylene,
Obtained by polymerizing in the presence of alicyclic hydrocarbons such as cyclohexene, chlorinated solvents such as 1,2-dichloro)Lrr-thane, carbon tetrachloride, etc.2, usually at 80°C to 100°C for 12 to 36 hours. I can do it. These manufacturing methods are described in Japanese Patent Application No. 58-29786, Japanese Patent Application No. 58-84626, and the Yohashi Collection of the Society of Polymer Science and Technology (Vol. 33, No. 2, p. 181).

The obtained polymer is a white fibrous or powdery polymer. Its number average molecular weight is usually 10,000 by light scattering method.
or more, preferably 100,000 or more. TaC as a catalyst
When e5 and TaBr5 are used, a polymer with a high molecular weight is obtained.

In the present invention, the polyorganosiloxane having active hydrogen in the side chain has the general formula (wherein R3 is an alkyl group having 1 to 4 carbon atoms or a halogenated alkyl group, R4 and R5 are hydrogen, and
an alkyl group or a halogenated alkyl group.

It is a phenyl group. n is 1-1000, m is 0-1
It is an integer of 000. ) Examples include polymers having structural units represented by the following. Examples of these products include:
-81 (manufactured by Nippon Unicar Co., Ltd.).

In addition, the polyorganosiloxane having active hydrogen at the terminal in the present invention has the general formula (in the formula, Ra, R7, R8, R1+ are alkyl groups having 1 to 4 carbon atoms or halogenated alkyl groups, and P is 1 to 2000). is an integer).

The polymer force having the structural unit shown is +f.

An example of these products is PSO51 (manufactured by China's SP Development Department).

When copolymerizing a substituted acetylene polymer and a polyorganosiloxane, the weight ratio of the two (not limited to this but can be varied in various ways) is usually 90:10 to IQ.
: 90, preferably 70: 80 to 80: 7
It is 0. If the substituted acetylene polymer is thicker than 90 (1, the stability of the film over time will be slightly lacking, and the siloxane introduction effect will be less), and if it is less than 10, the film forming ability will be lacking (
do.

Active hydrogen group (-SiH group) of polyorganosiloxane
The ratio is usually 1.1-0.01. Preferably l:l~0
It is 5.

Copolymerization of a substituted acetylene polymer and a polyorganosiloxane is usually carried out by dissolving both in a common solvent, such as an aromatic hydropeptahydrogen solvent such as benzene or toluene, an ether solvent such as tetrahydrofuran or dioxane, or a mixed solvent thereof. It will be done. The polymer concentration is usually 0.01 to 10% by weight for both in the solvent, preferably 0.5
The concentration is ~3% by weight. When the concentration is higher than 10% by weight, gelation tends to occur. The reaction can be carried out by adding about 1 to 11,000 pp of chloroplatinic acid. The reaction temperature is about 60 to 70°C from room temperature, and the reaction time is about several hours. Reactivity remaining in the latter half of these reactions -5
Any olefinic monomer to eliminate iH.

Alcohol etc. can be added. Examples of olefinic monomers include styrene, methyl methacrylate, hinyl acetate, α-olefin (1-hekey 12:/, 1-/
Examples of alcohol include methanol, ethanol, and higher alcohols.

After the reaction, the copolymer is usually reprecipitated in methanol, dried, and taken out.

Checking the copolymer is verified by obtaining an IR spectrum of the copolymer. The IR spectrum of the copolymer can be obtained by dissolving the copolymer in toluene or the like and casting it into a film.

The unreacted part of the acetylene polymer -SiH is 215
Characteristic absorption was observed between 0 and 2200 cm-'.
Absorption based on i-〇- appears greatly at 100θ to 1100cm = ivy. Polyorganosiloxanes having active hydrogen in side chains or terminals have high methanol solubility, so in the case of simple mixing, unreacted polyorganosiloxanes are excluded when reprecipitated in methanol, and when blended with IR forms, phase separation occurs even if a film is formed. However, in the detailed explanation of the present invention, the copolymerization of the present invention is confirmed because a uniform film cannot be obtained.

The obtained copolymer was prepared using an aromatic hydrocarbon solvent (toluene,
xylene, etc.), ether solvents (dioxane, tetrahydrofuran, etc.), chlorine solvents (carbon tetrachloride, ethylene dichloride, etc.) and cast to form a film to obtain a gas separation membrane.

The membrane of the present invention is made of the above copolymer. The film thickness is usually 0.01 to 100μ in order to have practical strength and a sufficient amount of gas permeation, and preferably 0.01 to 100μ, preferably 0 to 2μ.
The film of the present invention can be produced by a known method (Japanese Unexamined Patent Publication No. 166908/1984, etc.). Specifically, a film can be obtained by casting a solution of the polymer onto a solid (eg, glass, metal) or liquid surface (eg, water surface) with a smooth surface and evaporating the solvent. the polymer solution at the liquid level,
In particular, the method of obtaining an ultra-thin film by dropping a polymer solution onto the water surface and allowing it to spread and spread itself on the water surface yields a separation membrane with good membrane spreadability and a large area with few pinholes or extremely weak parts. This makes it easier. In addition, it can also be obtained by known molding methods for thermoplastic resins (such as extrusion molding).

The membrane of the present invention may be a copolymer of a substituted acetylene polymer and a polyorganosiloxane, but it may also be one processed with another second component. for example.

Polyorganosiloxanes with poor film-forming ability (such as dimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane and their derivatives) may be added, or various olefin polymers such as 4-methylpentene may be added. Methods for adding the above-mentioned second component include coating the membrane of the present invention with the second component (e.g., JP-A-57-4208M) and mixing the polymer represented by the general formula (1) with other second components. One method is to create a film using The amount of the polymer in the present invention when used in combination with the second component is usually 20% by weight or more, preferably 50% by weight or more in the membrane.

Furthermore, various additives (for example, plasticizers) may be added to the membrane of the present invention as necessary to improve the spreadability of the ultrathin membrane.

The membrane of the present invention may be in any form such as a flat membrane, a tubular membrane, or a hollow fiber.

The membrane of the present invention can also be formed into a composite membrane with a support, if necessary. Extraction method and paper making method are used as supports.

Porous supports made by various methods such as phase separation method and stretching method [e.g. Japanese paper, F3 paper 1 synthetic paper.

Filtration membrane, ultrafiltration membrane, plastic porous membrane (polypropylene porous membrane, etc.)] 9 knitted fabric-like supports (cloth, etc.),
Examples include non-woven supports (such as non-woven fabrics), wire mesh, and the like. The method of compounding may be a known method, such as applying a solution of the copolymer of the present invention onto a support, or pressing a film formed on the water surface onto the support, or scooping it up.

It can be made into a composite with the support by suctioning and adhering it through the support. An adhesive or the like may be present between these supports and the membrane for support.

Furthermore, the membrane supported on the support may be heat-treated.

The gas separation membrane of the present invention usually has an oxygen permeability coefficient of 50×10
'~1.0X10-'cc-cm/cm"・sec-
cmHg, and the separation coefficient between oxygen and nitrogen is usually 2.
．． It is 0 to 4.0.

〔Example〕 , The present invention will be further explained below with reference to Examples.

The present invention is not limited to this.

Examples 1 to 6 Various acetylene monomers shown in Table 1 were mixed with 10% of toluene.
0m (prepared at a ratio of 0.1mog per liter, TaCe5
was added as a catalyst and polymerization was carried out at 30°C overnight, producing a viscous polymer gel. This polymer gel was diluted and dissolved in toluene, precipitated in a large amount of methanol, purified, and dried to obtain various substituted acetylene polymers. After drying, this polymer was redissolved in toluene to form a solution of 1. A polyorganosiloxane having an active hydrogen side chain was added to 100 g of this polymer solution, and -81
(manufactured by Nippon Unicar Co., Ltd.), and active hydrogen (
-5iH) as a polyorganosiloxane
O51 (manufactured by Chisso's SP Development Department) was used, and the same weight as the above various acetylene polymers was added, and a chloroplatinic acid solution (tetrahydrofuran solution 1%) was added as a reaction catalyst.
．． 5me was added and the reaction was stirred at room temperature for 5 hours. After the reaction, it was poured into methanol to be reprecipitated and taken out. The resulting copolymer was dried, redissolved in toluene, and then cast onto a glass plate to create a permeable membrane. Next, using a gas permeability measuring device manufactured by Rika Seiki Kogyo, the gas permeability (gas permeability coefficient) of each membrane was measured at 25° C., and the separation coefficient was determined. The results are shown in Table 1'.

Examples 7 to 9 A thin film active layer was prepared using a trimethylsilylpropyne polymer (hereinafter abbreviated as PMSP) and the siloxane copolymer prepared in Examples 1 and 2, and 1-7-! - Semipermeable membrane obtained from a polymer of Ni-2-chloroacetylene (
A composite membrane was prepared using the following method (Japanese Patent Publication No. 58-8416λ). The composite membrane was created using water surface membrane properties. (Specification of Japanese Patent Application No. 1987-87207). The thickness of the active layer is 0.1
/j was set constant. The changes in oxygen permeability of the obtained composite membrane over time were measured, and the results are shown in Table 2.

Table 2 [Effects of the present invention] The membrane of the present invention is excellent in both gas permeability 1 separation factor and thinning properties. That is, it has better permeability than polydimethylsiloxane, has a better separation coefficient for oxygen and nitrogen than polydimethylsiloxane, and can be easily formed into a thin film that is equal to or better than that of olefin polymers. Furthermore, the outstanding feature of the present invention is the performance of this separation membrane (
It has excellent stability over time in terms of gas permeability, etc. This feature becomes extremely important when it is put into practical use as a gas separation membrane such as an oxygen enrichment membrane.

Since the membrane of the present invention exhibits the above-mentioned effects, it can be incorporated into a device for producing oxygen-enriched air from air and used to improve the combustion efficiency of engines, boilers, heating appliances, and the like. In addition, we are working in the field of turbocharger shear replacement to increase engine combustion efficiency, heating furnaces that reach temperatures of over 1000℃,
It is expected to save energy by 30 to 50% when used in baking P and glass melting furnaces. Furthermore, as clean oxygen-enriched air, it can be used as an incubator for premature babies, a treatment device for patients with respiratory diseases, an artificial lung, an artificial gill, and contact lenses.

An example of an oxygen-enriched combustion device incorporating the membrane of the present invention is Nikkei Plastics, October 1981 issue, 8.
The oxygen-enriched combustion system described on p.

[Brief explanation of the drawing]

FIG. 1 shows infrared absorption spectra of the copolymer and polytrimethylsilylpropyne obtained in Example 1.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (In the formula, R is a C_1 to_1_2 linear or branched alkyl group, or a Si-containing alkyl group. A gas separation membrane characterized in that it is formed from a copolymer of a substituted acetylene polymer having a repeating unit represented by (a) and a polyorganosiloxane having an active hydrogen in a side chain or at a terminal.