JPH029430A - Gas separation membrane and composite gas separation membrane - Google Patents

Abstract

PURPOSE:To obtain a gas separation membrane wherein decrease of permeation rate of gas is small even under conditions of high temperature and high humidity by employing polymers, as gas separation membrane, which is obtained by the reaction of polyorganosiloxane containing vinyl groups with vinyl monomer. CONSTITUTION:For preparing gas separation membrane for separation and concentration of gas mixture, polyorganosiloxane such as dimethyl polysiloxane containing vinyl groups, etc., is reacted with vinyl monomer such as styrene monomer etc., to produce a polymer. Gas separation membranes composed of a mixture of said polymer with polymer of fumaric acid ester and its copolymer in a ratio of 10 to 90wt.% are superposed upon a porous supporting film and further the first polymer as mentioned first is superposed thereupon. As a result, a gas separation membrane with a large proportion of siloxane structure and having high membrane strength is obtained, whereby decrease of permeation rate of gas is small ever if it is placed under conditions of high temperature and high humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a gas separation membrane and a gas separation composite membrane used to separate and concentrate a mixed gas.

BACKGROUND OF THE INVENTION In recent years, many gas separation membranes using organic polymers have been proposed. Separate oxygen from the air at low cost using a gas separation membrane!
If it can be enriched, it can be burned and made into iron.

It is expected that it will be able to make significant contributions to the fields of ceramics, waste treatment, and medicine.

Oxygen separation membranes have a large ability to selectively separate oxygen from oxygen-containing gases such as air, and a large ability to efficiently transmit oxygen.
It is required that the oxygen selectivity coefficient and oxygen permeability coefficient be large. When separating and concentrating oxygen from air, the oxygen selection coefficient α is expressed by the value of (oxygen permeability coefficient)/(nitrogen permeability coefficient).

Generally, as the oxygen selectivity coefficient of an organic polymer increases, the oxygen permeability coefficient tends to decrease. From a practical standpoint, the strength of the oxygen separation membrane is also required.

The gas component 11111 has a small oxygen selectivity coefficient (α = about 2) and a large oxygen permeability coefficient, and has strengthened the membrane strength.
1, a copolymer of organopolysiloxane and polycarbonate (Japanese Unexamined Patent Publication No. 121485/1985),
Mixture of polyfunctional polymer and terminal functional polymer and α, ω-
A bifunctional polyfunctional polyalkyl methyl methyl siloxane type copolymer (Japanese Patent Application Laid-open No. 71006/1983) is known.

On the other hand, polymethylpentene and polyphenylene oxacite are known as organic polymers with a large oxygen selectivity coefficient. Polymers of fumaric acid esters have also been reported as materials with large oxygen selectivity coefficients (Japanese Patent Laid-Open No. 61-423
Publication No. 20). These organic polymers have sufficiently high membrane strength, and although their oxygen permeability is inferior to polysiloxanes and their copolymers, they can obtain a high concentration of oxygen.

One of the methods for making organic polymers into thin films is to spread organic polymers dissolved in a solvent on the water surface, evaporate the solvent, form a gas separation membrane, and then apply this to a porous support membrane. There is a method of transferring it to a computer (Japanese Unexamined Patent Publication No. 56-92926, etc.). Regarding methylpentene, a method is known in which a thin film is obtained by adding a polyorganosiloxane copolymer to methylpentene (Japanese Unexamined Patent Publication No. 102907/1983).

Problem to be Solved by the Invention Dissolving an organosiloxane copolymer in a solvent, spreading it on the water surface to form a gas separation membrane, and laminating the obtained gas separation membrane directly on a porous support membrane. The gas separation composite membrane has the disadvantage that the permeation flow rate of the gas decreases if it is left in a high temperature environment.

On the other hand, the inventors have already proposed that a gas separation membrane is formed by dissolving polymethylpentene, polyphenylene oxide, fumaric acid ester polymers, and their copolymers in a solvent and spreading them on the water surface. method (method of providing an adhesive layer on a porous support membrane, method of forming irregularities on a porous support membrane with a flexible polymer, or method of impregnating a porous support membrane with a solvent that does not attack the separation membrane) A gas separation composite membrane in which a gas separation membrane is laminated on a porous support membrane using a method of adhesion) has a large oxygen separation coefficient α of 3 or more;
WI element permeability is not very good (it has been found that it is not possible to obtain a large amount of oxygen-enriched air in practical use. Also,
This gas separation composite membrane also has the disadvantage that when left in high temperature and high humidity, gas permeation is reduced more than that of organosiloxane copolymers.

In view of the above-mentioned drawbacks, the present invention provides a gas separation membrane that exhibits a small decrease in gas permeation flow rate even when left in high temperature and high humidity, has a large oxygen selectivity coefficient, has excellent oxygen permeability, and is provided with However, a gas separation membrane with a small decrease in gas permeation flow rate,
The present invention aims to provide a gas separation composite membrane.

Means for Solving the Problems The gas separation membrane of the present invention is a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer, and a polymer of this polymer and a fumaric acid ester, and The copolymer is mixed in an amount of 10 to 90% by weight.

Furthermore, the gas separation composite membrane of the present invention includes a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer, a polymer of a fumaric acid ester, and a copolymer thereof, on a porous support membrane. A gas separation membrane formed by mixing 10 to 90% by weight of the above is laminated, and a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer is further laminated thereon.

If the proportion of siloxane structures in the working gas separation membrane is large,
Even when left in high temperature and high humidity environments, the gas permeation flow rate decreases little.

Therefore, from the standpoint of separation, a single polyorganosiloxane membrane is preferable, but its membrane strength is low, so
It cannot be used as a single thin film.

Since the present invention is composed of a polymer obtained by reacting a polyorganosiloxane and a vinyl monomer, it becomes a gas separation membrane with a large proportion of siloxane structure and strong membrane strength, so that even when left in high temperatures, the gas separation membrane The decrease in permeation flow rate is small.

In addition, although the gas permeation flow rate decreases significantly at high temperatures, the above polymers are mixed with fumaric acid ester polymers and copolymers thereof, which have a large oxygen selectivity coefficient (α = about 3.5). By doing so, the oxygen selectivity coefficient becomes thicker ((α=
2.5 or higher), and due to the presence of a polymer containing a siloxane structure in the gas separation membrane, it has good oxygen permeability, and the gas permeation rate decreases little even when left in high temperature and high humidity. A separation membrane is obtained.

On the other hand, the gas separation composite membrane of the present invention has a large oxygen selectivity coefficient ((α=
2.5 or more), it is possible to obtain a gas separation composite membrane having a structure in which a polymer containing a siloxane structure covers the outermost surface, and the decrease in gas permeation flow rate is even smaller even when left in high temperature and high humidity. Become.

Examples Examples of the present invention will be described below. The present invention is not limited to this example.

[Example 1] 50.0 g of dimethylpolysiloxane containing a vinyl group (trade name rsH41c, manufactured by Tomu Silicone Co., Ltd.)
Monochlorobenzene 600mf! 10.0 g of styrene monomer was added thereto, and 2,5 dimethyl 2,5 di(tert-butylperoxy)hexane (product name of Nippon Oil & Fats Co., Ltd., "Perhexa 25BJ") was added as a peroxide. After adding 0.25g, it was degassed with nitrogen gas and reacted in a nitrogen atmosphere at a temperature of 120°C for 12 hours.This polymerization solution was poured into 5e of methanol to obtain a precipitate. The precipitate was purified to obtain a polymer of dimethylpolysiloxane and styrene.

This polymer was dissolved in benzene to prepare a benzene solution weighing 2 parts by weight, and 5% by weight of tetrahydrofuran was added to this solution to prepare a film forming solution.

This membrane forming solution was dropped onto the water surface to form a thin film, and two layers were laminated on polyether sulfone as a porous support membrane to obtain a gas separation composite membrane.

[Example 2] In Example 1, the amount of styrene monomer was 20.0 g, and the same conditions as Example 1 were used for the amount of other substances, polymerization method, membrane forming solution preparation method, and membrane forming method. I got it.

[Example 3] Equal weights of the polymer of dimethylpolysiloxane and styrene monomer polymerized in Example 1 and polyditertiary butyl fumarate were taken, and 2 of these two types of polymers were
A benzene solution of 10% by weight was prepared, and 10% by weight of tetrahydrofuran was added to this solution to obtain a film forming solution.

This membrane-forming solution was dropped onto the water surface to form a thin film, and two layers were laminated on polyethersulfone as a porous support membrane to obtain a gas separation composite membrane.

[Example 4] Ditertiary butyl fumarate was used instead of polyditertiary butyl fumarate in Example 3, and a 5% by weight copolymer of this and vinyl acetate was used to prepare a film forming solution and a film forming method. A gas separation composite membrane was obtained under the same conditions as in Example 3.

[Example 5] The membrane forming liquid was prepared under the same conditions as in Example 1, and the obtained membrane forming liquid was dropped onto the water surface to form a thin film, and then applied on the gas separation composite membrane obtained in Example 4. A gas separation composite membrane was obtained by laminating one layer.

[Example 6] Ditertiary butyl fumarate was used instead of polyditertiary butyl fumarate in Example 3, and a 5% by weight copolymer of it and vinyl acetate was used, and polysulfone was used as the porous support membrane. A gas separation composite membrane was obtained under the same conditions as in Example 3 regarding the membrane forming solution preparation method and membrane forming method. Further, on this gas separation composite membrane, the membrane forming liquid was prepared under the same conditions as in Example 1, and this membrane forming liquid was dropped onto the water surface to form a thin film, and one layer was laminated to form a gas separation composite membrane. Obtained.

[Comparative Example 1] A copolymer of α,W bis(diethylamino)polydimethylsiloxane, polyhydroxystyrene, and polysulfone was dissolved in benzene to prepare a 2% by weight benzene solution, and further 8% by weight was added to this solution. % of tetrahydrofuran and furan were added to prepare a film forming solution. This film-forming solution is dropped onto the water surface to form a thin film, and a porous support film is made of polypropylene (trade name of polyplastic ■ "Duraguard #240").
Two layers were laminated on OJ to obtain a gas separation composite membrane.

[Comparative Example 2] 5% by weight of ditertiary butyl fumarate and vinyl acetate
A 3% by weight benzene solution was prepared by dissolving the copolymer in benzene, and further, 2% by weight of monochlorobenzene and 5% by weight of tetrahydrofuran were added to this solution to prepare a film forming solution. . This film forming solution was dropped onto the water surface to form a thin film. Polypropylene (
Product name of Polyplastic Co., Ltd. “Duraguard #2”
400J) was immersed in methanol, and after taking it out, methanol on one surface was wiped off with filter paper.

Then, it was placed on the thin film formed on the water surface and laminated on a porous support membrane to obtain a gas separation composite membrane.

The membrane performances of the gas separation composite membranes of Examples and Comparative Examples are shown in the table.

The figure also shows the rate of change in the oxygen permeation flow rate in a storage test at a temperature of 60° C. and a relative humidity of 95%.

The measurement conditions were: effective membrane area 11.3 cj, measuring pressure 1.0 f/cj, ? 11 The temperature was set at 25°C.

(Hereinafter, blank space) Effects of the Invention As described above, according to the present invention, since the present invention is made of a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer, the storage characteristics under high temperature and high humidity are improved. A good gas separation membrane can be obtained.

In addition, since this polymer is mixed with a fumaric acid ester polymer with a high oxygen selectivity coefficient and its copolymer to obtain a gas separation membrane, its oxygen selectivity coefficient is high and it cannot be left in high temperature and high humidity. Excellent characteristics. Furthermore, since a mixed gas separation membrane with a large oxygen selectivity coefficient (and excellent moisture resistance) is laminated on the porous support membrane, and the above-mentioned polymer with excellent moisture resistance is further laminated on top of that, The oxygen selectivity coefficient is large,
It is possible to provide a highly reliable gas separation composite membrane with even better storage characteristics under high temperature and high humidity conditions.

[Brief explanation of the drawing]

The figure is a characteristic diagram showing the rate of change in the oxygen permeation flow rate in a storage test of a gas separation composite membrane in an atmosphere at a temperature of 60° C. and a relative humidity of 95%.

Claims (5)

[Claims] (1) A gas separation membrane comprising a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer. (2) The gas separation membrane according to claim 1, wherein the vinyl monomer is a styrene monomer. (3) A gas separation membrane made of a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer is mixed with 10 to 90% by weight of a fumaric acid ester polymer and its copolymer. A gas separation membrane characterized by: (4) A gas separation membrane made of a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer is mixed with 10 to 90% by weight of a fumaric acid ester polymer and its copolymer. layered on a porous support membrane, and further layered on top of that is a gas separation membrane made of a polymer obtained by reacting a polyorganosiloxane containing a vinyl group with a vinyl monomer. A gas separation composite membrane featuring: (5) The gas separation composite membrane according to claim 4, wherein the porous support membrane is at least one of polyethersulfone and polysulfone.