JPH0316971B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing ultrathin polymer membranes. More specifically, the present invention relates to a method for producing an ultrathin polymer membrane having high permeability to mixed gases. The present inventors have previously discovered that a 1-monoalkyldimethylsilylpropyne polymer is a gas permeable material with higher permeability and practical selectivity, and also found that during film formation of this polymer, It has been proposed that aromatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons can be used as solvents (Japanese Patent Application No. 58-29786); It was inappropriate to obtain this. The inventors of the present invention have conducted intensive studies on methods for easily obtaining ultrathin films, and have discovered that the above object can be achieved by using a specific solvent, resulting in the present invention. That is, the general formula of the present invention An aliphatic hydrocarbon solution of a 1-monoalkyldimethylsilylpropyne polymer having a repeating unit represented by (wherein R is a C _1-4 linear or branched alkyl group) is spread on the water surface. This is a method for producing an ultra-thin polymer film, characterized by forming an ultra-thin film of the polymer. In general formula (1), the C _1-4 straight or branched alkyl group in R ₁ includes straight chain alkyl groups such as methyl, ethyl, propyl, butyl groups; branched alkyl groups such as isobutyl group, tertiary alkyl group, etc. Examples include a butyl group. 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, and the like. 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 , TaCl ₅ , NbBr ₅ , TaBr ₅ ), and in the presence of a solvent ( (usually at 30°C)
It can be obtained by polymerizing at ~100°C 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 (polymers such as tertiary-butylacetylene, neopentylacetylene, and tertiary-pentylacetylene, preferably tertiary-butylacetylene polymers), vinylorganosilane polymers (vinyltrimethylsilane, Polymers such as vinyltriethylsilane and vinyltripropylsilane, preferably vinyltrimethylsilane polymers), polyorganosiloxanes (dimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, etc.), cellulose polymers (ethyl cellulose, hydroxy Ethyl cellulose, triacetyl cellulose, etc., preferably ethyl cellulose), α-olefin polymer (4
-methylpentene-1 polymer), alkyl sulfone polymer (copolymer of α-olefin and SO ₂ , preferably an alkyl group with 10 to 20 carbon atoms)
long-chain alkyl sulfone polymers), tertiary amine-containing polymers (vinylpyridine polymers, N,
N-diethylaminoethyl acrylate polymer,
Examples include N,N-dimethylaminostyrene polymer, 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. The aliphatic hydrocarbon solvent used in the preparation of the aliphatic hydrocarbon solution in the present invention is a linear or branched saturated or unsaturated aliphatic carbon having a boiling point of usually 30 to 99°C, preferably 35 to 70°C. Hydrogen such as n-pentane, n-hexane, isohexane,
n-heptane, n-octane, isooctane, 1-
Examples include hexane, 1-heptene, petroleum ether, and the like. Preferred among these are n-hexane and petroleum ether. Particularly preferred is petroleum ether. This aliphatic hydrocarbon solvent may include other solvents such as alicyclic hydrocarbon solvents (cyclohexane, cyclohexene, methylcyclohexane, ethylcyclohexane, etc., preferably cyclohexane), aromatic hydrocarbon solvents (benzene, toluene, o, m- or p-xylene, styrene, ethylbenzene, naphthalene, etc., preferably benzene and toluene), halogenated hydrocarbon solvents (carbon tetrachloride, 1,2,3
-trichloropropane, trichloroethylene, chloroform, chlorobenzene, chloroethylbenzene, etc., preferably 1,2,3-trichloropropane), and two or more of these may be used in combination.
When used in combination with other solvents, the content of aliphatic hydrocarbons in the total solvent is usually 50% by weight or more, preferably 70% by weight or more. Additives such as alcohols, phenols, ketones, aldehydes, amines, or two or more of these may be added to these solvents in order to improve the spreadability of the water surface film. The amount of these additives is usually less than 10% by weight of the solvent. In the present invention, the concentration of the 1-monoalkyldimethylsilylpropyne polymer and optionally other polymers in the solution is usually 0.001 to 1.0% by weight, preferably
It is 0.01-0.5% by weight. If the concentration is less than 0.001% by weight, defects are likely to occur in the thin film spread on the water surface, resulting in pinholes. Furthermore, if the concentration exceeds 1% by weight, the viscosity of the polymer solution increases and it is difficult to uniformly spread it into a thin film. Examples of methods for spreading the polymer solution on the water surface include adding or dropping the solution onto the water surface. When a polymer solution is dropped without being added to the water surface, it immediately spreads over the water surface to form an extremely thin film. When an aliphatic hydrocarbon solution of a polymer is spread on a water surface to form an extremely thin film of the polymer, it is preferable to maintain the temperature of the polymer solution and the temperature of water within a certain temperature range in advance. The temperature of the polymer solution is preferably 20 to 50°C, and this temperature is 20°C.
If it is lower, the viscosity of the polymer solution will increase and it will be difficult to spread it into a thin film. When the temperature of the polymer solution is higher than 50°C, the solvent tends to volatilize and wrinkles easily when spread on the water surface. On the other hand, the temperature of the water is preferably 5
-30°C, particularly preferably 10-25°C. If this temperature is lower than 5℃, the viscosity of the polymer solution will increase and it will be difficult to spread into a thin film.
If the temperature is higher than ℃, the solvent will easily evaporate,
A polymer solution dropped onto the water surface is difficult to spread out on its own. In the present invention, when obtaining an ultrathin film by using the 1-monoalkyldimethylsilylpropyne polymer (A) and other polymers (B) together, the method is (1) starting from a solution of the mixture of the two components. The film can be formed by the same method as the invention. The thickness of the film formed by casting on the water surface and drying can be varied depending on the molecular weight of the polymer used and the concentration of the polymer solution, but is usually 1 μm or less (for example, 0.01 to 1 μm). easily by using a polymer with a large molecular weight at a low concentration.
Ultra-thin films of about 0.1μ can be created. It is also possible to form thicker films using highly concentrated solutions. Since the ultrathin membrane obtained by the present invention has little self-supporting properties, a support is usually required when used as a gas separation membrane. Porous materials such as Japanese paper, nonwoven fabric, synthetic paper, paper,
Examples include cloth, porous ceramics, porous metals, precision membranes, and ultrafiltration membranes. By combining with these supports, it can be used satisfactorily as a membrane for gas separation. The compositing method can be a known method, for example, a film formed on the water surface can be brought into close contact with the support by pressure, scooped up, or brought into close contact with the support through suction to create a composite with 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 present invention is a method by which ultrathin polymer films can be easily obtained. This ultra-thin film has an extremely high oxygen permeability coefficient, which is usually between 10 ^-2 and 10 ^-4 (CC
(STP)/cm ² , sec, cmHg). Further, the ratio of oxygen to nitrogen permeability is usually in the range of 1.5 to 3.0. From the above, this ultra-thin film is epoch-making superior to the oxygen-enriching films known to date, and exhibits sufficiently satisfactory performance for practical use.
Moreover, the separation coefficient can be increased by using other polymers in combination. The ultra-thin membrane obtained by the method of the present invention is useful as a gas separation membrane, and can be incorporated into equipment for producing oxygen-enriched air from air, such as engines, boilers, etc.
It can be used to improve the combustion efficiency of heating appliances, etc. In addition, it is used in the field of turbocharging to increase engine combustion efficiency, and is used in heating furnaces, firing furnaces, and glass melting furnaces that reach high temperatures of 1000℃ or more.
is expected to save energy. 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 a contact lens. Examples will be further described below with reference to Examples, but the present invention is not limited thereto. Examples 1 to 10 1-trimethylsilylpropyne polymer (hereinafter referred to as
It's called PMSP. ). (The intrinsic viscosity of PMSP is toluene.
It is 6.9 at 30℃. PMSP alone or mixed with other polymers was dissolved in the aliphatic hydrocarbon shown in Table 1 and other solvents as necessary. 5 ml of the polymer solution was gently pipetted onto a stainless steel water bath with a base area of 30 cm square. The polymer solution spontaneously spread into a circular shape, and an ultrathin film formed when the solvent evaporated. The thickness and area of the obtained ultra-thin film were measured and shown in Table 1.

[Table] Example 11 The ultra-thin film created in Example 4 was coated with Jyuragard 2400.
(a porous polypropylene membrane), and the same ultrathin membrane was placed on top of it, and this process was repeated four times. When the gas permeation rate (CC(STP)/cm ² , sec, cmHg) of the resulting ultra-thin composite membrane was measured, the oxygen permeation rate was 3.2×10 ^-2 and the nitrogen permeation rate was 2.0×
It was 10 ^-2 . Example 12 A composite membrane was prepared by stacking the ultra-thin membrane prepared in Example 5 into four layers in the same manner as in Example 11, and the amount of gas permeation was measured. The amount of oxygen permeation was 2.2×10 ⁻² and the amount of nitrogen permeation was 1.1×10 ⁻² .

Claims (1)

[Claims] 1. General formula An aliphatic hydrocarbon solution of a 1-monoalkyldimethylsilylpropyne polymer having a repeating unit represented by (wherein R is a C _1-4 linear or branched alkyl group) is spread on the water surface. A method for producing an ultra-thin polymer film, which comprises forming an ultra-thin film of the polymer. 2. The manufacturing method according to claim 1, wherein the amount of the polymer is 0.001 to 1% by weight based on the weight of the aliphatic hydrocarbon solution. 3. The manufacturing method according to claim 1 or 2, wherein the ultra-thin film has a thickness of 1 μm or less.