JPH0471570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas separation membrane. More specifically, the present invention relates to a gas separation membrane having excellent gas permeability and permselectivity. In recent years, methods using thin polymer films have been attracting attention as a means of separating and concentrating specific gases (oxygen, nitrogen, etc.) from mixed gases (air, etc.). The present inventors previously discovered that 1-monoalkyldimethylsilylpropyne polymer is an excellent material with excellent gas permeability, but as a result of further investigation, it was found that the above polymer and vinyl The inventors have discovered that by combining triorganosilane polymers, it is possible to obtain a gas separation membrane that maintains excellent gas permeability and has further improved separation performance, resulting in the present invention. That is, the present invention is based on the general formula (In the formula, R ₁ is a linear or branched alkyl group having 1 to 12 carbon atoms.) This is a gas separation membrane formed from a mixed polymer of silane polymer (B). In general formula (1), the C _1-12 linear or branched alkyl group of R ₁ is a linear alkyl group such as methyl, ethyl, propyl, butyl, benzyl,
Hexyl, heptyl, octyl, nonyl, decyl, dodecyl groups, etc.: branched alkyl groups such as isobutyl group, tertiary butyl group, etc. Examples of the 1-monoalkyldimethylsilylpropyne used to obtain the polymer having the unit represented by the general formula (1) include 1-trimethylsilylpropyne, 1-mono-n-propyldimethylsilylpropyne, and 1-mono-mono-n-propyldimethylsilylpropyne. -n-hexyldimethylsilylpropyne, 1-mono-n-decyldimethylsilylpropyne, and the like. Among these, preferred is 1-trimethylsilylpropyne. 1-Trimethylsilyl-1-propyne is a commercially available monomer (a product of Betrak Co., Ltd. in the United States, a product of Chitsuso Co., Ltd.
SP developed product T3728) can be used. This polymer is produced by polymerizing the above monomers in the presence of a catalyst based on group V transition metals niobium (Nb) and tantalum (Ta) (e.g. halides such as NbCl ₅ , TaCl ₅ , NbBr ₅ , TaBr ₅ etc.). It can be obtained by The manufacturing method is based on the patent application No. 58-29786.
-154106). In addition, this polymer is polymerized using the above monomers as the main catalyst, using a catalyst based on niobium or tantalum, and using an organoaluminum compound (such as trialkylaluminum, mono- or dihalodi- or monoalkylaluminium) as a co-catalyst. You can get it. The details of the manufacturing method can be found in Japanese Patent Application No. 58-84626 (Japanese Unexamined Patent Publication No. 59-84) filed by the present applicant entitled "Process for manufacturing polymers".
210915). 1-Monoalkyl (alkyl group is _C1-12 ) dimethylsilylpropyne polymer is usually a white solid with a high molecular weight and an intrinsic viscosity of usually 0.5 (dl/
g) That's all. The polymer is soluble in aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbons (carbon tetrachloride, chloroform, etc.), alicyclic hydrocarbons (cyclohexane, etc.), and mixtures of two or more of these. The vinyltriorganosilane polymer (B) used in the present invention has the general formula (In the formula, R ₂ is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R ₃ and R ₄ are an alkyl group, a cycloalkyl group, or an aryl group.) Examples include organosilane polymers. _R2 , _R3 ,
Examples of the alkyl group for R ₄ include alkyl groups having 1 to 12 carbon atoms, specifically the same groups as R ₁ in general formula (1). Examples of the cycloalkyl group include a cyclohexyl group. An example of the aryl group is a phenyl group. Specific examples of vinyltriorganosilane include:
Vinyltrimethylsilane, vinyltriethylsilane, vinyl triplepylsilane, vinyltributylsilane, vinyldimethylethylsilane, vinyldimethylpropylsilane, vinyldiethylpropylsilane, vinyltricyclohexylsilane, polydimethylcyclohexylsilane, vinyldimethylphenylsilane, and these Examples include mixtures of two or more of the following. Among these, vinyltrimethylsilane is preferred. Vinyltriorganosilane polymers also include copolymers of vinyltriorganosilane of general formula (2) and other vinyl monomers. In this case, other vinyl monomers include styrene, isobutylene, methyl methacrylate, and the like. The content of vinyltriorganosilane units in the vinyltriorganosilane polymer is usually 70% by weight or more. The manufacturing method of vinyltriorganosilane polymer is as follows:
It can be produced by polymerizing vinyltriorganosilane in the presence of a known catalyst based on a transition metal compound of groups B to B of the periodic table or an organometallic compound of an element of group ~. Preferably, an alkyllithium such as methyllithium, ethyllithium, n-propyllithium, n-butyllithium, or n-pentyllithium is used as a catalyst, and an aliphatic hydrocarbon such as n-hexane, cyclohexane, n-pentane, benzene, toluene, It can be obtained by polymerizing vinyltriorganosilane, usually at 0 to 50°C for 4 to 100 hours, using a solvent such as an aromatic hydrocarbon such as xylene. Vinyltriorganosilane polymer (B) is a white powder with an intrinsic viscosity of 0.1g at 25℃ in toluene.
(dl/g) or more. Vinyltriorganosilane polymer (B) contains aromatic hydrocarbons (benzene, toluene, etc.), aliphatic hydrocarbons (n-hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), and halogenated hydrocarbons (dichloromethane, dichloromethane, etc.). (chloroethylene, tetrachlorethylene, chloroform, dichlorobenzene, etc.)
and dissolves in two or more of these. The membrane of the present invention is a membrane formed from a mixed polymer of polymer (A) and polymer (B). The weight ratio of (A) and (B) can be varied over a wide range, for example from 10/90 to 90/10, but in order to obtain a highly permeable separation membrane, (A) should be mixed with (A).
It is preferable to use 50% or more based on the weight of (B). An example of a method for obtaining a gas separation membrane formed from polymer (A) and polymer (B) is to form a membrane from a solution mixture of the two components by a known method. (A) or (B) is a common solvent such as aromatic hydrocarbons such as benzene, toluene, and xylene, alicyclic hydrocarbon solvents such as cyclohexane, carbon tetrachloride,
A known method for obtaining a membrane from a solution mixture by dissolving it in a chlorinated solvent such as chloroform
166903, etc.) Specifically, a film can be obtained by casting a polymer solution onto a solid (eg, glass, metal) or liquid surface (eg, water surface) having a smooth surface and evaporating the solvent. the polymer solution at the liquid level,
In particular, the method of obtaining an ultra-thin membrane by dropping a polymer solution onto the water surface and allowing it to spread spontaneously on the water surface has good membrane spreadability and can yield a separation membrane with a large area with few pinholes or extremely weak parts. It becomes easier. In addition, it can also be obtained by a known molding method (extrusion molding method) for thermoplastic resin. The membrane of the present invention may be processed with another third component. For example, in order to further increase gas permeability, a film may be formed by adding polyorganosiloxane (dimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, and its derivatives, etc.) with poor film forming properties.
Various olefinic polymers including methylpentene may also be added. Methods for adding the other third component include coating the membrane of the present invention with the above-mentioned third component (for example, JP-A No. 57-4203), and adding another third component to the polymer (A) and polymer (B). An example is a method of mixing to form a film. When a third component is used in combination, the amount of polymer (A) and polymer (B) in the present invention is usually 50% or more, preferably 70% 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 have any shape such as a flat membrane, a tubular membrane, or a hollow fiber. The thickness of the membrane of the present invention is usually 0.01-100μ, preferably 0.05-20μ, in order to have practical strength and obtain sufficient gas permeability. The membrane of the present invention can also be composited with a support, if necessary. As a support, extraction method, paper making method,
Porous supports made by various methods such as phase separation method and stretching method [e.g. Japanese paper, filter paper, synthetic paper, filtration membrane, ultrafiltration membrane, porous plastic membrane (polypropylene porous membrane, etc.)], ed. Examples include woven supports (cloth, etc.), nonwoven supports (nonwoven fabrics, etc.), wire mesh, and the like. The method of compositing may be a known method, for example, by pressurizing a membrane formed on the water surface onto a support, scooping it up, suctioning it through a support, or compositing it with a 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 has a normal oxygen permeability coefficient.
10 ^-9 to 10 ^-7 cc・cm/cm ³・sec・cmHg,
The separation factor between oxygen and nitrogen is usually in the range of 2.0 to 5.0. The membrane of the present invention has excellent gas permeability, separation properties, and thinning properties (processability). That is, it retains the excellent gas permeability of the 1-molar alkyldimethylsilylpropyne polymer and has further improved separation properties.
It also has superior permeability compared to vinyltriorganosilane polymers. Because of the above effects, the membrane of the present invention can be incorporated into a device for producing oxygen-enriched air from air, and can be used to improve the combustion efficiency of engines, boilers, heating appliances, and the like. In addition, the field of turbocharger replacement that increases engine combustion efficiency, 1000
It is expected to save energy by 30 to 50% when used in heating furnaces, firing furnaces, and glass melting furnaces that reach temperatures above ℃. Further, as normal oxygen-enriched air, it can be used as an incubator for premature babies, a treatment device for patients with respiratory diseases, or as artificial lungs, artificial gills, and contact lenses. An example of an oxygen-enriched combustion device incorporating the membrane of the present invention is the oxygen-enriched combustion system described in Nikkei Plastics, October 1981 issue, page 8. The present invention will be further explained below with reference to production examples and examples, but the present invention is not limited thereto. Production example 1 (1) Polymer (A) Trimethylsilylpropyne in 100ml of toluene
Add 0.1mol to TiCl3 as a catalyst, 1mmol
In addition, polymerization was carried out at 80°C for one day and night. The resulting polymer gel was diluted and dissolved in toluene, and purified by precipitation in a large amount of methanol. This polymer was designated as Polymer (A). (Molecular weight 1.1 million). (2) Polymer (B) 1.0 mol of vinyltrimethylsilane was mixed with n-butyllithium as a catalyst in 80 ml of n-hexane.
Polymerization was carried out using 0.8 mM at room temperature under a nitrogen atmosphere overnight. The resulting polymer was purified by precipitation in a large amount of methanol. Polymerize this polymer
(B). (Molecular weight 20,000). Examples 1 to 6 Toluene solutions of Polymer (A) and Polymer (B) alone and at the mixing ratio (based on weight) shown in Table 1 were prepared. The polymer concentration in the solution was 2%. A toluene solution of each polymer was cast onto a glass plate and casted to create a separation membrane. Next, the gas permeability coefficients of oxygen and nitrogen were measured at 25°C using a gas permeability measuring device manufactured by Rika Seiki Kogyo, and the separation coefficient was determined. The results are shown in Table-1. The unit of gas permeability P is (10 ^-8 cm ³ (STP)·cm/cm ² ·sec·cmHg). 【table】

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ is a linear or branched alkyl group having 1 to 12 carbon atoms.) A gas separation membrane formed from a mixed polymer of silane polymer (B). 2 (B) is a general formula (In the formula, R ₂ is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R ₃ and R ₄ are an alkyl group, a cycloalkyl group, or an aryl group.)
The separation membrane according to claim 1, which is a vinyltriorganosilane polymer having a repeating unit represented by: 3. The separation membrane according to claim 1 or 2, wherein the content of (A) is 50% or more based on the weight of (A) and (B). 4. The separation membrane according to any one of claims 1 to 3, wherein (B) is a vinyltrimethylsilane polymer.