JPH0446172B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to gas separation membranes. More specifically, the present invention relates to a gas separation membrane having high selectivity. In recent years, methods using polymer separation membranes have been attracting attention as a means of separating and concentrating specific gases from mixed gases. The present inventors previously discovered that 1-monoalkyldimethylsilylpropyne polymer is an excellent material with excellent gas permeability, but as a result of further studies, it was found that 1-monoalkyldimethylsilylpropyne polymers are mainly The present inventors have discovered that when a gas separation membrane is heat-treated, it exhibits excellent high selectivity while maintaining good permeability, leading to the present invention. That is, the present invention relates to a 1-monoalkyldimethylsilylpropyne polymer {however,

[Formula] does not contain the structural unit. Here, R ¹ is hydrogen or an alkyl group, and R ² is an alkyl group. }
This is a highly selective gas separation membrane characterized by comprising a heat-treated membrane. In 1-monoalkyldimethylsilylpropyne, the alkyl group usually has 1 to 1 carbon atoms.
12, preferably 1 to 4, in which the alkyl group R having 1 to 12 carbon atoms in general formula (1) is a straight chain alkyl group such as methyl, ethyl, propyl, butyl group, etc. ; Branched alkyl groups such as isobutyl group, tertiary butyl group; hexyl, cyclohexyl, peptyl group, etc.; Examples of 1-monoalkyldimethylsilylpropyne used to obtain a polymer having a repeating unit represented by general formula (1) include 1-trimethylsilylpropyne, 1-monoethyldimethylsilylpropyne, and 1-mono-n -propyldimethylsilylpropyne, 1-mono-n-butyldimethylsilylpropyne, 1-mono-n-peptylsilylpropyne,
Examples include 1-mono-laurylsilipropine. Among these, preferred is 1-trimethylsilylpropyne. As 1-trimethylsilylpropyne, a commercially available monomer (product of Petrarch Company, USA, product T3728 of SP Development Department of Chitsuso Corporation) can be used. The method for obtaining this polymer is as follows: in the presence of a catalyst based on group V transition metals niobium (Nb) and tantalum (Ta) (for example, NbCl ₅ , NbBr ₅ , TaBr ₅ ),
In addition, in the presence of a solvent (aromatic hydrocarbons such as benzene, toluene, xylene, alicyclic hydrocarbons such as cyclohexene, chlorinated solvents such as 1,2-dichloroethane, carbon tetrachloride, etc.), the temperature is usually 30°C to 100°C.
It can be obtained by polymerizing at ℃ for 12 to 36 hours. It can also be obtained by the method described in Japanese Patent Application No. 58-84626. The obtained polymer is a white fibrous or powdery polymer. Its number average molecular weight is usually 10,000 or more, preferably 100,000 or more, as measured by a light scattering method. In the present invention, the 1-monoalkyldimethylsilylpropyne polymer may be used in combination with other polymers, if necessary. Other polymers include 1-alkyne polymers (ternary butylacetylene,
Polymers such as neopentylacetylene, tertiary pentylacetylene, preferably tertiary butylacetylene polymers), vinylorganosilane polymers (polymers such as vinyltrimethylsilane, vinyltriethylsilane, and vinyltripropylsilane, preferably vinyl trimethylsilane polymer), polyorganosiloxane (dimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, etc.), cellulose polymer (ethylcellulose, hydroxyethylcellulose, triacetylcellulose, etc., preferably ethylcellulose), α-olefin type polymers (such as polymers of 4-methylpentene-1), alkyl sulfone polymers (copolymers of α-olefin and _SO2 , preferably those in which the alkyl group has 10 to 10 carbon atoms)
(20 long-chain alkyl sulfone polymers, etc.), the third
grade amine-containing polymers (vinyl pyridine polymers,
Examples include N,N-diethylaminoethyl acrylate polymer, N,N-dimethylaminostyrene polymer, and preferably vinylpyridine polymer. When the monoalkyldimethylsilylpropyne polymer and the second component (another polymer) are used together, the content of the monoalkyldimethylsilylpropyne polymer is usually 50% by weight or more, preferably 70% by weight or more. In the present invention, the method for creating a gas separation membrane mainly formed from a monoalkyldimethylsilylpropyne polymer is as follows: (1) A composite membrane is created by coating a porous gas with a solution in which the above polymer is dissolved in a solvent. method, (2) dissolving the above polymer in a solvent;
After coating on a porous substrate, the polymer is placed in a coagulation bath that is a non-solvent to create a so-called asymmetric membrane, and (3) the polymer is dissolved in a solvent and then spread on the water surface to form a so-called asymmetric membrane. Create a thin film on the water surface,
One method is to stack it on a porous base material to form a composite membrane. Regarding these specific methods, please refer to Japanese Patent Application No. 1984-136222, Japanese Patent Application No. 186334, and Japanese Patent Application No. 1983.
-200559 and Japanese Patent Application No. 58-242775. To obtain a heat-treated 1-monoalkyldimethylsilylpropyne polymer membrane, which is a feature of the present invention,
Any heating device capable of achieving temperatures between 100°C and 250°C may be used. They are broadly classified into two methods: dry heat treatment in gas and wet heat treatment in a medium. Active gas (N ₂ ,
It can be obtained by heat treatment in Ar, CO ₂ or a mixture thereof). Heating may be carried out by circulating air or in a vacuum dryer, or by using an infrared lamp. High frequency heating is also effective. As a method of moist heat treatment in the medium of 1.
- It is necessary to choose an inert medium for the monoalkyldimethylsilylpropyne polymer membrane. They are,
Examples include water, alcohols, organic acids, organic solvents such as DMF (dimethyl formaldehyde) and DMSO (dimethyl sulfoxide), ketones, and mixtures thereof. The treatment time is usually one minute or more and several hours or less, but since the treatment time varies greatly depending on the temperature and the wet heat or dry heat method, it is necessary to select optimal conditions. The gas separation membrane of the present invention is mainly formed from a 1-monoalkyldimethylsilylpropyne polymer, and has improved gas permeation selectivity while maintaining good gas permeability. Since it has the above effects, it can be applied to various gas separation membranes. Application examples include oxygen enrichment membranes (combustion, medical), hydrogen separation membranes (H ₂ /CO separation, H ₂ recovery from ammonia synthesis purge gas), CH ₄ /CO ₂ separation membranes (for methane fermentation, It can be used in a wide range of applications, including tertiary oil recovery), artificial lungs, artificial carp materials, and membranes for air electrodes. The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. Example 1 1-trimethylsilylpropyne polymer (hereinafter referred to as
The intrinsic viscosity of PMSP is toluene, 30
6.9 °C) dissolved in toluene (1%
weight concentration). The solution was cast onto a glass plate and cast to form a thick film. After drying under reduced pressure at room temperature for 10 hours, the thickness of the film was measured to be 40μ. Thereafter, it was heat treated at 150°C for 1 hour in a circulating air dryer. Thereafter, the oxygen and nitrogen permeability coefficients of the unheated film and the heat treated film were measured using a gas permeation evaluation device manufactured by Rika Seiki Kogyo (manufactured by Rika Seiki Kogyo Co., Ltd.). The results are shown in Table 1.

[Table] Example 2 PMSP and polyvinyltrimethylsilane (hereinafter
PVMS) was dissolved in toluene at a weight ratio of 0.8:0.2. A thick film (thickness: 31 μm) was obtained in the same manner as in Example 1. Heat treatment is at 120℃ in air.
I went there for 2 hours. Table 2 shows the evaluation results of gas permeability (permeability coefficient, separation coefficient).

[Table] Example 3 PMSP used in Example 1 was dissolved in tetrahydrofuran at 1% by weight. The solution was cast onto a glass plate using a 350μ applicator, a portion of the solvent was evaporated for 10 seconds at room temperature, and the solution was poured into ice water to solidify. Further, the membrane was immersed in running water for a day and night to completely remove the solvent, and then air-dried to prepare a dry asymmetric membrane. Thereafter, heat treatment was performed under the same heat treatment conditions as in Example 1. Table 3 shows the results of evaluating each gas permeability.

[Table] Example 4 PMSP was dissolved in n-hexane at 1.5% by weight. Furthermore, an activator of sorbitan oleate monoester with HLB4.3 was added to this solution at a rate of 0.005%.
It was added in an amount of % by weight. When 0.4 g of the solution was gently added onto the water surface (tap water was used) in a 30 cm square stainless steel water bath (15°C), a polymer thin film was formed. The average film thickness was calculated from the film area of the obtained ultra-thin film to be about 0.1μ. A composite membrane was prepared using this thin membrane as a porous support layer and a semipermeable membrane of 1-phenyl-2-chloroacetylene polymer (Japanese Patent Publication No. 34164/1983). Heat treatment was performed in the same manner as in Example 1. Table 4 shows the results of evaluating gas permeability.

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Claims (1)

[Scope of Claims] 1 1-monoalkyldimethylsilylpropyne polymer {However, it does not contain the structural unit of [Formula]. Here, R ¹ is hydrogen or an alkyl group, and R ² is an alkyl group. } A highly selective gas separation membrane comprising a heat-treated membrane. 2 1-monoalkyldimethylsilylpropyne polymer has the general formula The membrane according to claim 1, which is a polymer having a repeating unit represented by the formula (wherein R is _{a C1-12 alkyl} group). 3. The membrane according to claim 1 or 2, wherein the heat-treated body is heat-treated at a temperature of 100 to 250°C.