JPS61146321A - Permselective compound membrane for gas - Google Patents

Abstract

PURPOSE:To obtain a permselective compound membrane for gas having high gas permeability and high permeability coefft. ratio for O2/N2 by forming a high molecular extremely thin film portion on a porous supporting body to a two-layered structure and prepg. the uppermost layer thereof from an acetylenic polymer. CONSTITUTION:The first layer of the high molecular extremely thin film adjoining to a porous supporting body is made of a copolymer or crosslinked product of polyorganosiloxane compd., and the second layer consists primarily of a polyacetylenic polymer expressed by the formula. Preferred thickness of the extremely thin film part is 0.01-0.2mum, An extremely thin film is prepd. by the developing method on the water surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to selective gas permeable composite membranes used for gas separation.

Conventional technology The use of homogeneous ultra-thin polymer membranes as gas separation membranes is less expensive and easier to handle than conventional cryogenic liquefaction methods or adsorption separation methods using adsorbents. It has been attracting attention recently due to its advantages. Among these, there is particular interest in oxygen enrichment membranes that concentrate oxygen from air.

This oxygen-enriching membrane has already been put into practical use in some cases, one being in an oxygen-enriching combustion system and the other being an oxygen-enriching device for medical use. The characteristics of the former membrane are that it has low gas separation (oxygen and nitrogen) but high gas permeability, and the latter has low gas permeability but high gas separation. be. Although such a difference is inevitably determined by the intended use, it is also due to the lack of a material that has high gas separation properties and excellent gas permeability. If a film that satisfies both of these properties is developed, it will become a vibrant film that is not limited by use, and its market will expand significantly.

Problems to be Solved by the Invention In order to solve these problems, recently KM in polymer thin films has been developed.
There have been reports on the development of a fully crystalline blended membrane and a composite membrane of a plasma-polymerized membrane of silicone monomers, but their characteristics are
In either case, the separation performance is high, but the permeability is low, and problems remain in terms of membrane durability.

Therefore, an object of the present invention is to provide a composite membrane with high gas permeability corresponding to conventional silicone-based composite membranes and to improve gas separation performance.

Means for Solving the Problems The present invention provides a two-layer structure for the homogeneous ultra-thin polymer film portion of a selective gas permeable composite membrane consisting of a porous support and a homogeneous ultra-thin polymer film. Since the second layer provided on the first layer in contact with the first layer is made of acetylene-based polymer, it has high gas permeability and separation property of 2.
6-4.6 (oxygen.

We have achieved a membrane with an extremely superior permeability coefficient ratio).

Function: The homogeneous ultra-thin polymer film of the present invention is characterized by having a two-layer structure. The first effect in this case is that high gas permeability and high separability can be obtained, which cannot be achieved with each layer alone. Second, even if there are pinholes or defects in each layer, sufficient properties can be obtained by combining the layers.

Thirdly, the support.

Adhesion between the first layer and the second layer is excellent, and film formation is very simple. In particular, in the case of hard polymers with high glass transitions such as acetylene, defects are likely to occur and an additional overcoat on top of 2N was thought to be necessary, but with the structure of the present invention, this is not necessary and excellent gas permeability is achieved. A selective gas permeable composite membrane exhibiting properties was obtained.

The first layer in contact with the porous support of the ultra-thin polymer film of the present invention is polyorganosiloxane, a copolymer with polyorganosiloxane, polydimethylsiloxane, or a crosslinked product of polydimethylsiloxane.

Polyhydroxystyrene-polydimethylsiloxane copolymer, polyhydroxystyrene-polysulfone-polydimethylsiloxane ternary copolymer, and polydimethylsiloxane block copolymer are desirable, and as the second layer, an acetylene polymer ultrathin film is generally used. The formula is (where R1 is a hydrogen atom or an alkyl group such as a methyl group or an ethyl group, or a chlorine or fluorine atom), a rogene atom, R
2 is a linear or branched alkyl group having 1 to 5 carbon atoms or a phenyl group, and -8i (CH
s) This is a layer mainly composed of an acetylene polymer represented by s + -Si (trialkylsilyl group such as (zH''s) s).

The thickness of the homogeneous ultra-thin film part of this composite film is 0.0
A range of 1 μm to 0.20 μm is preferred. Furthermore, the more the layers of the homogeneous ultra-thin polymer film portion have a multilayer structure, the more pinholes can be prevented and the separation properties of the film can be improved.

Example Embodiments of the present invention will be described below with reference to the drawings.

[Example 1] The figure shows a cross-sectional view of a selective gas permeable composite membrane in an example of the present invention.

In the figure, 1 is a porous support, 2 is a first layer of an ultra-thin polymer film directly adhered to the porous support 1, and 3 is a second layer of an ultra-thin polymer film provided thereon. , is characterized by its two-layer structure.

By the way, as a porous support, Duragard 2400 (
Polydimethylsiloxane (Toshi Silicone 5R-410) was used as a homogeneous film material.
A composite membrane made of a single material was created using i. The production of ultra-thin films of polymers is based on polydimethylsiloxane: PDMS.
After preparing a 0 wt% benzene solution, this solution was dropped onto the water surface, and the OPDMS film thickness was adjusted by contacting the ultra-thin film that spontaneously spread on the water surface with the support. The amount of solution added was controlled, and as a result, a composite membrane having the characteristics shown in Table 1 was obtained.

Table 1 The area of the water surface was 30 x 30 cm.

In this way, PDMS alone increases gas permeability, but
Separability is low and saturates at about 2.0.

Next, the porous support uses Duraguard 2400,
Polymethylsilylprobin (Mw: 1.2 million): PMS Pi was used as a homogeneous ultra-thin polymer film material. This material was obtained by polymerizing trimethylsilylpropyne (manufactured by Chisso Corporation) monomer using a tantalum hexachloride catalyst.

A 2% by weight benzene solution of this material was prepared and the PD
In the same way as for MS, drop the solution on the water surface to remove PM.
An ultra-thin film of SP was fabricated. A porous support was brought into contact with this thin film on the water surface, but the adhesion was poor and it was not possible to form a composite, so the film was vacuum-suctioned to form a composite. Further, the film thickness was controlled by laminating identical films. The properties of the composite membrane thus obtained are shown in Table 2.

As shown in Table 2, this material had very good gas permeability, but the oxygen to nitrogen separation ratio was small, ranging from about 1.6 to 2.5.

As shown in Table 2, the gas permeability properties of PDMS and PMSP are excellent in both cases, but the gas separation is low, with the highest value of approximately 2.4 for the oxygen and nitrogen separation ratio. It is.

Therefore, as shown in the figure, a first layer 2 is first formed on a porous support 1.
PDMSfjI: After adhesion, PMSPi was laminated as the second layer 3 and its gas permeability was measured.
The oxygen permeation rate is 1.31×1O-1cc/sec-(
y-atm, the separation ratio of oxygen and nitrogen was 3.2, showing a high separation performance that would be unimaginable with a single material.

[Example 2] Similar to Example 1, the ultra-thin polymer film layer had a two-layer structure, the first layer 2 was made of polyhydroxystyrene (PH8)-polysulfone (PS)-PDMS copolymer, and the second layer 3 was made of polyhydroxystyrene (PH8)-polysulfone (PS)-PDMS copolymer. PM to
A composite membrane was manufactured using SP. The result is Example 1
Similarly, the oxygen permeation rate is 1-82 x 10 cc/
sec--4tm, and the separability of oxygen and nitrogen is very high at 2.80, so in the example, PMSP was used as the acetylene polymer, PDMS was used as the silicone material, and PH8-PS-PDMS copolymer was used. Although the combination is shown above, other acetylene polymers and silicone materials have similar physical properties and gas permeability, and those skilled in the art can easily infer that similar effects can be obtained.

Effects of the Invention In summary, the present invention is characterized in that a porous support and a homogeneous thin polymer film provided thereon have a two-layer structure, and the second layer is made of an acetylene polymer. It has the advantage of providing high gas permeability and gas separation properties that cannot be obtained with a single material.

[Brief explanation of the drawing]

The figure is a sectional view of a selective gas permeable composite membrane in a first embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Porous support, 2...1st layer ultra-thin polymer film, 3...2nd layer ultra-thin polymer film.

Claims (9)

[Claims] (1) A porous support and a homogeneous ultra-thin polymer film provided on the porous support, wherein the ultra-thin polymer film has two
1. A selective gas permeable composite membrane having a layered structure, wherein a second layer provided on the first layer in contact with a porous support is made of an acetylene polymer. (2) The selective gas permeable composite membrane according to claim 1, wherein the first layer of the homogeneous ultra-thin polymer membrane is a polyorganosiloxane or a copolymer with a polyorganosiloxane. (3) The selective gas permeable composite membrane according to claim 1, wherein the first layer of the homogeneous ultra-thin polymer membrane contains polydimethylsiloxane or a crosslinked polydimethylsiloxane as a main component. (4) The selective gas permeable composite membrane according to claim 1, wherein the first layer of the homogeneous ultra-thin polymer membrane is a polyhydroxystyrene-polydimethylsiloxane copolymer. (5) The selective gas permeable composite membrane according to claim 1, wherein the first layer of the homogeneous ultra-thin polymer membrane contains a polyhydroxystyrene-polysulfone-polydimethylsiloxane terpolymer as a main component. (6) The selective gas permeable composite membrane according to claim 1, wherein the first layer of the homogeneous ultra-thin polymer membrane is a block copolymer of polydimethylsiloxane. (7) The general formula for the second layer of a homogeneous ultra-thin polymer film is ▲Math.
There are chemical formulas, tables, etc.▼ (However, R_1 is a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or a halogen atom such as chlorine or fluorine, R
_2 is a linear or branched alkyl group having 1 to 5 carbon atoms or a phenyl group, or -Si(CH_
3) The selective gas permeable composite membrane according to claim 1, characterized in that the main component is an acetylene polymer represented by a trialkylsilyl group such as _3 or -Si(C_2H_5)_3. (8) The thickness of the homogeneous ultra-thin polymer film layer is 0.01 μm or more
The selective gas permeable composite membrane according to claim 1, characterized in that the membrane has a thickness in the range of 0.20 μm. (9) The selective gas permeable composite membrane according to claim 1, wherein each of the first layer and the second layer of the homogeneous ultra-thin polymer membrane has a multilayer structure.