JPH04317734A - Gas separating composite membrane and its production - Google Patents

Abstract

PURPOSE:To provide an excellent diffusibility and a high reliability with respect to a gas separating composite membrane for use in the separation and concn. of a gaseous mixture. CONSTITUTION:The polysiloxane chlorobutane solution (contg. 10% tetrahydrofuran) hardenable by contact with water having at its terminal portion an alkoxy group is dropped onto the surface of water to form a silicone rubber protecting membrane composed of networks. A gas separating membrane consisting of the copolymer of a dimethylpolysiloxane with styrene monomer and polydi-t-butyl fumarate in a weight ratio of 1:1 is laminated in two layers on the gas separating membrane of a porous supporting membrane of polyether sulfone to form a gas separating composite membrane. In this way, the membrane strength can be made larger and the protecting membrane can be made thinner to increase the diffusibility.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas separation composite membrane used for separating and concentrating a gas mixture, and a method for manufacturing the same.

0002

BACKGROUND OF THE INVENTION In recent years, many gas separation membranes using organic polymers have been proposed. If oxygen in the air could be concentrated at low cost using gas separation membranes, it could make a significant contribution to fields such as combustion, ceramics, waste treatment, and medicine. Gas separation membrane materials for oxygen concentration have a high ability to selectively separate oxygen from oxygen-containing gases such as air and a high ability to permeate oxygen, that is, oxygen selectivity coefficient and oxygen permeability. A large coefficient is required. Furthermore, from the viewpoint of manufacturing gas separation membranes, it is required that a homogeneous thin film be obtained and that the formed membrane have a predetermined strength. As gas separation membrane materials for oxygen concentration, copolymers of organopolysiloxane and polycarbonate, mixtures of polyfunctional polymers and terminally functional polymers, and α,ω-2 functional polyalkylsiloxanes are used. Crosslinked copolymers, polymethylpentene, fumarate ester polymers and their copolymers, and polytrimethylsilylpropyne have been reported.

In practice, a structure has been reported in which these gas separation membranes are supported on a support membrane and a protective film is provided on top of these gas separation membranes in order to ensure reliability. For example, a gas separation composite membrane having a structure provided with a protective film of a copolymer of a polyorganosiloxane having a vinyl group and a vinyl monomer has been reported (see JP-A-2-9430). Since the amount of gas permeating through a gas separation composite membrane is inversely proportional to the thickness of the gas separation membrane and the protective membrane, it is necessary to make the gas separation membrane and the protective membrane as thin as possible.

0004

[Problems to be Solved by the Invention] However, in the above conventional configuration, polyorganosiloxane is dissolved in an organic solvent and spread on the water surface to create a protective film, so it is difficult to completely dissolve the polyorganosiloxane in the organic solvent. However, it also needs to spread homogeneously, and the polyorganosiloxane is a linear polymer or has a low molecular weight so that it can be dissolved in organic solvents. Therefore, considering the membrane strength and the diffusion of polyorganosiloxane into the gas separation membrane and even into the porous support membrane, it is necessary to increase the thickness of the polyorganosiloxane protective membrane in order to ensure reliability. However, there was a problem in that the permeability was poor and a sufficient flow rate could not be obtained.

The present invention solves the above-mentioned conventional problems and aims to provide a highly reliable gas separation composite membrane with excellent permeability.

[0006]

[Means for Solving the Problem] In order to achieve this object, the gas separation composite membrane of the present invention has a gas separation membrane made of a polymer layered on a porous support membrane, and The protective film has a structure in which silicone rubber that reacts with water and hardens to form a network structure is laminated. Also,
The method for manufacturing the gas separation composite membrane of the present invention is to dissolve a cured polysiloxane in an organic solvent, drop a certain amount of this solution onto the water surface, spread it uniformly, and then separate the gas consisting of a polymer after the solvent evaporates. This is a method in which a protective film made of silicone rubber that reacts with water and hardens to form a network structure is laminated on top of the gas separation membrane by contacting a porous support membrane on which the membranes are laminated.

[0007]

[Operation] With this structure, a solution of low molecular weight curable polysiloxane dissolved in an organic solvent is spread on the water surface as a protective film, so it spreads very well on the water surface and forms a homogeneous thin film on the water surface. This thin film reacts with water, resulting in the formation of a thin film of silicone rubber with a network structure on the water surface. Furthermore, by spreading polysiloxane, which cures by reacting with water, on the water surface to form a thin film, sufficient water necessary for curing can be supplied.

[0008]

【Example】

(Example 1) An example of the present invention will be described below.

As a material for the gas separation membrane, 2% by weight of chlorobutane (tetrahydrofuran is added to
(containing 0%) solution and the surface size is 60cm x 6
0.15c above the water surface approximately in the center of a 0cm square aquarium
c dripped. After the chlorobutane has evaporated and formed a gas separation membrane, gently place polyether sulfone as a porous support membrane on top of this gas separation membrane and once the porous support membrane and gas separation membrane have completely adhered, gently remove it from the water surface. I peeled it off. A gas separation membrane was again formed on the water surface in the same manner, and the porous support membrane on which one layer of gas separation membrane had been laminated was gently placed, and two layers of gas separation membrane were laminated.

Next, as a material for the protective film, polysiloxane (polysiloxane) having an alkoxy group at the end, which cures by reacting with water, is used.
Manufactured by Toray Silicone Co., Ltd., product name "SE9157"
Prepare a 5% by weight chlorobutane (containing 10% tetrahydrofuran) solution of
0.10 on the water surface approximately in the center of a 60cm square aquarium.
cc dripped. After the chlorobutane has evaporated and a protective film has been formed, a porous support film with two layers of gas separation membranes is gently placed on top of this protective film, and when the gas separation membrane and protective film have completely adhered, gently remove the membrane from the water surface. I peeled it off. A protective film was again formed on the water surface in the same manner, and a gas separation membrane composite membrane was created in which two layers of the protective film were laminated on top of the gas separation membrane.

(Example 2) Two layers of gas separation membranes were laminated on a porous support membrane in the same manner as in Example 1. Next, as a material for the protective film, 5% by weight of chlorobutane (containing 10% tetrahydrofuran) of polysiloxane having an alkoxy group at the end (manufactured by Toray Silicone Co., Ltd., trade name "SE9176") that cures by reacting with water is used. ) prepare the solution,
0.10 cc of the solution was dropped onto the water surface approximately in the center of a square aquarium with a surface size of 60 cm x 60 cm. After the chlorobutane has evaporated and a protective film has been formed, gently place a porous support film with two layers of gas separation membranes on top of this protective film, and when the gas separation membrane and protective film have completely adhered, gently peel it off from the water surface. did. A protective film was formed on the water surface in the same manner again to create a gas separation composite membrane in which two layers of the protective film were laminated on the gas separation membrane. In order for polysiloxane to cure by reacting with water at room temperature, the polysiloxane should have an alkoxy group, acetoxy group, ketoxime group, aminoxy group, etc. as a reactive group in the side chain or terminal.

Table 1 compares the initial performance of the gas separation composite membrane according to this example and a conventional gas separation composite membrane using a copolymer of polyorganosiloxane having a vinyl group and a vinyl monomer as a protective film. It shows.

[0013]

[Table 1]

As is clear from Table 1, the gas separation composite membrane according to this example provides excellent effects in terms of oxygen permeation flow rate.

The measurement conditions shown in Table 1 were as follows: effective membrane area was 11.3 cm2, measurement pressure was 1.0 kg/cm2, and measurement temperature was 25°C. Also, 60 as a reliability test.
Even in a standing test for 1000 hours at 95% RH, there was no decrease in the oxygen selectivity coefficient, similar to the conventional example.

As described above, according to this embodiment, the silicone rubber formed by thinning and then curing a curable low molecular weight polysiloxane has a network structure, has a high film strength, and is resistant to solvents. Since it is also insoluble in water, the thickness of the protective film can be reduced, and a gas separation composite membrane with high permeability can be obtained.

[0017]

As described above, the present invention has a gas separation membrane made of a polymer layered on a porous support membrane, and a protective film that reacts with water and hardens to form a network structure. The protective film is created by dissolving hardening polysiloxane in an organic solvent, dropping a certain amount of this solution onto the water surface, spreading it uniformly, and after the solvent evaporates, the polymer By contacting a porous support membrane laminated with a gas separation membrane made of This makes it possible to realize a gas separation composite membrane with excellent properties and high reliability.

Claims (2)

[Claims] 1. A gas separation membrane made of a polymer is laminated on a porous support membrane, and a silicone rubber which reacts with water and hardens to form a network structure is placed on the gas separation membrane as a protective film. Laminated gas separation composite membrane. Claim 2: A porous support film in which a solution of curable polysiloxane dissolved in an organic solvent is dropped onto the water surface in a certain amount and spread uniformly, and after the solvent has evaporated, a gas separation membrane made of polymer is laminated. A method for producing a gas separation composite membrane, in which a protective film of silicone rubber, which is cured by reacting with water to form a network structure, is laminated on the gas separation membrane.