JPS60257820A - Gas separation composite membrane - Google Patents

Abstract

PURPOSE:To obtain a composite membrane prevented from the delamination of the membrane and support membrane thereof and excellent in separation permeability, by interposing an extremely thin membrane comprising a polyorganosiloxane/silphenylene copolymer between a porous support and an extremely thin membrane comprising a polymer having high gas separation capacity. CONSTITUTION:An extremely thin membrane C comprising a polyorganosiloxane/silphenylene copolymer having a repeating unit represented by formula is interposed between a porous support A and an extremely thin membrane B comprising a polymer having high gas separation capacity to form a gas separation composite membrane. The extremely thin membrane B pref. comprises poly (4-methylpenten-1) or polyvinyl trimethylsilane and the thickness thereof is 0.01-0.3mum. The n/m ratio of the constitutional unit of the extremely thin membrane C is 5-20 and the thickness thereof is pref. 0.01-0.3mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas separation composite membrane. More specifically, the present invention relates to a gas separation composite membrane effective for obtaining oxygen-enriched air from air by a membrane separation method.

[Conventional technology]

In recent years, gas separation by demethods, particularly methods for obtaining oxygen-enriched air by membrane separation, have attracted attention. This membrane separation is used for cars.
- A membrane that is suitable for use must satisfy the conditions of high body separation properties and high gas permeability. Therefore, the form of the membrane needs to be a composite membrane in which a thin membrane material with gas separation properties is combined with a porous support. Until now, as the composite membrane, a polyorganosiloxane silphenylene copolymer composite membrane (Japanese Patent Application Laid-Open No. 57-122
906), but the polyorganosiloxane silphenylene copolymer had the drawback of low separation performance.

On the other hand, membrane materials with high gas separation performance, such as polyphenylene oxide and poly(4-methylpentene-1), are made into thin films and composited directly onto a porous support.
Due to poor adhesion, there was a drawback that the thin film would peel off when handling the composite film.

In order to solve this problem, as described in U.S. Pat. No. 3,874,986, a polycarbonate/polydimethylsiloxane (P
A composite membrane in which a thin film of C-PDMS) copolymer is interposed has been proposed.

However, the PC-PDMS copolymer has an oxygen permeability coefficient po of 2-3 (GCRS(TP) ・Cm/
cm'·riec, lcn·Hg), and the thin film layer interposed to improve adhesion deteriorates the permeation performance of the composite membrane.

[Problem that the invention seeks to solve]

An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a gas regulation composite membrane in which the thin film layer does not peel off from the porous support membrane and has excellent gas separation performance and gas permeation performance.

[…” Means for resolving points of interest]

The present invention has the following configuration to achieve the above object.

That is, between the porous support A and the ultra-thin film B made of a polymer having high gas separation properties, an ultra-thin film C made of a polyorganosiloxane/L-phenylene copolymer having the structural formula: This is a gas separation composite membrane formed by intervening membranes.

The porous support A according to the present invention may be anything that supports a thin film, such as Japanese paper, nonwoven fabric, and synthetic paper.

P paper, cloth, wire mesh. Examples include filtration membranes, ultrafiltration membranes, etc. Among them, ultrafiltration membranes are preferred because smoothness of the surface and smaller pores are more durable in terms of reinforcement. Limited '4
Specific examples of the filtration membrane include a polysulfone porous support membrane, a polyethersulfone porous support membrane, a polypropylene porous support membrane, and a polyfluoroethylene porous support membrane. These porous supports A
The shape may be sheet-like, tubular, fibrous, etc., but is not particularly limited.

Next, what is the ultra-thin film B made of a polymer having high gas separation properties in the present invention? Any polymer may be used as long as it has high gas separation properties and relatively good gas permeability, but the following polymers are preferred in terms of the balance of thin film forming properties, gas separation properties, and gas permeability.

Vinyl polymers of poly(4-methylbenzone-1), polyethylene/propylene copolymers, and polyvinyltrimethylsilane.

The general formula.

(However, field is an integer of 1.2.3. R7ke-CH,.

-C-, H,, -1C, Hヮ, -C41(,, -C,
selected from the group consisting of alkyl groups of H, . ), or (or the general formula is).

0 111 40 C-N11-R, -1suH-C-0-R, +ri,
H40+, +C3H60+, +C4H2O+, -+C1
selected from the group consisting of H1oO. ), or the general formula is selected from the group consisting of -C,H,-, -C,H,-, -C4H,-. Here, m is an integer of 1.2.3).

Among them, particularly preferred are (d, poly(4methy)Iypentene-1) and polyvinyltrimethylsilane. The thickness of the ultra-thin film B is preferably 0.001 μm or more and less than 0.00 μm.

If the film thickness does not exceed 01 μm, bin holes will occur and the gas separation performance will deteriorate.

If it exceeds 0.03μ, the gas permeation resistance increases and the gas permeation performance of the composite membrane decreases, which is not preferable.

What is the polyorganosiloxane silphenylene copolymer in the present invention?

CH, CH, CH.

Upper 20 or below is good size 1-1. stomach. If less than 5,
If the gas permeability is low and exceeds 1, 2, or 20, thin film formation will be significantly impaired, so this is not recommended.

The molecular weight is 200,000 or more" - preferably 30,000 or more. If the molecular weight is less than 200,000, the thin film forming property will be significantly deteriorated, which is not preferable. Very thin film. The film thickness of C is preferably 01μ or more and 203μ or more.

If the film thickness is less than [], 01 μm, a lot of porpoise occurs, and the gas separation performance of the composite membrane deteriorates.

If it exceeds 0.03μ, gas permeation resistance increases, which is not preferable.

Next, the manufacturing method of the present invention will be explained. First, talk about polymers that have gas separation properties: benzene, toluene, and xylene. It is dissolved in a solvent such as dichloromethane, cycloD-ecune, cyclohexane, cyclohexene, tetrachloroethane, etc. to obtain a film-forming solution B'. .

A polyorkanosiloxane silphenylene copolymer is dissolved in a solvent such as cyclohexane, toluene, benzene, or tetrachloroethane to obtain a film forming solution C'.

The concentration is 0.01 = 5 wt, particularly preferably 0.00
Ro~2wt class is appropriate. The film-forming solution C' prepared in this manner is dropped onto the water surface in advance and spread, and a porous support is brought into contact with the solution to adhere a thin film of the polyorganosiloxane silphenylene copolymer.

Next, in a similar manner, a thin film of a polymer having a high gas content and monomer properties is attached to the thin film of the polyorganosiloxane silphenylene copolymer to form a composite film.

As described above, the composite film according to the present invention can be formed by simply spreading the film on the water surface/bringing the thin film into contact with the water surface and pulling it up.

The evaluation criteria for the characteristics that are suitable for the present invention are as follows.

(1) Gas permeability and gas separation properties The composite membrane for gas separation of the present invention is separated so that the pressure on the downstream side can be reduced to 2
atm. The pressure on the secondary side was set to Iatm, and the permeation rate of gas (oxygen, nitrogen≠) that had passed through the composite membrane was measured using a precision membrane flowmeter 5F-101 (manufactured by Stanstar Technology Co., Ltd.).

The oxygen permeation rate is defined as the gas permeation performance, and the separation 1 coefficient, which is the ratio of the oxygen permeation rate to the nitrogen permeation rate, is defined as r of the gas separation 1'1 ability.
It was set as p + filtration value standard.

(2) Adhesiveness On the surface of the ultra-thin film 8 of the composite membrane for gas component 1 of the present invention.

Separately, place the MLrv porous support at a pressure of 2 g/C.
After bonding under pressure at step m', the porous support film was peeled off.

The gas (oxygen or nitrogen) permeation rate of the composite membrane for gas separation after peeling was measured in the same manner as above. Oxygen permeation rate and separation (coefficient) were evaluated based on the difference between adhesive and after peeling.

〔Example〕

Next, embodiments of the present invention will be described based on Examples.

Example 1 Polyorganosiloxane silane:y copolymer P
SO95 (Chisso Co., Ltd. M Silphenylene/dimethylsiloxane co-lambda combined pressure = 115. Number average molecular weight 50
Oi vtt,% was adjusted by dissolving Oi vtt in cyclohexene. Spread this solution on the water surface.

Fluororesin porous membrane (product name: Fluorobor, manufactured by Sumitomo Electric Industries, Ltd.)
A composite membrane for gas separation is obtained by supporting a second thin film on the water surface. Next, poly(4 methylpentene-1) (trade name T P
-1~ to χ01. Mitsui Petrochemical Co., Ltd.) was dissolved in cyclohexene to prepare +01 vtt.

This solution was spread on the water surface, and the poly(4-methylpentene-1) thin film on the water surface was supported on the thin film surface of the previously prepared polyorganosiloxane silphenylene copolymer composite film, and gas separation was carried out. A composite membrane for 1 was created.

The thickness of the poly(4-methylpe/tene-1) thin film is approximately 0.
．． The thickness of the polyorganosylogisane silphenylene copolymer thin film was approximately 0.01 μm. Table 1 shows the results of measuring the oxygen permeation rate and oxygen/nitrogen separation coefficient of this composite membrane for gas separation.

Despite the presence of a thin film of polyorganosiloxane silphenylene co-conjugate, it had high gas permeability and high gas separation performance.

Example 2 Borifueni 1/n oxide (weight average molecular weight 〒50,
[)00) is dissolved in benzene to prepare a 0.5 wt% solution. This solution is spread on the water surface to form a thin film. A polyphenylene oxide thin film formed on the water surface was supported on the surface of a cylindrical organosiloxysansilphenylene copolymer composite membrane prepared in the same manner as in Example 1 to prepare a 9-gas separation composite membrane. The thickness of the polyphenylene oxide thin film of the composite membrane is approximately 0.04μ,
The thickness of the polyorganosiloxane silphenylene copolymer thin film was approximately 0.1 μm. The results of measuring the oxygen permeation rate and the separation coefficient between oxygen and nitrogen of this gas separation composite membrane are shown in Table 1. Both gas permeability and gas separation performance are excellent.

Example 6 A fluorine porous support membrane (trade name: Fluorobor, manufactured by Sumitomo Electric Industries, Ltd.) was adhered to the thin film surface of the gas separation composite membrane prepared in Example 1 at a pressure of 2 g 7 cm, and then peeled off. Table 2 shows the results of measuring the oxygen permeation rate and oxygen/nitrogen separation coefficient of the membrane.

Example 4 Table 2 shows the results of adhesive peeling performed on the gas separation composite membrane prepared in Example 2 in the same manner as in Example 6.

Both Example 4 and Example 4 showed gas separation performance before and after adhesive peeling.
It can be seen that the present invention has excellent adhesive properties, with no change in gas permeability.

Comparative Example 1 The poly(4-meralpentene-1)cyclohexene Q, j wt% solution prepared in Example 1 was spread on the water surface.

Form a thin film. This thin film is supported on a fluorine porous support membrane to produce a composite membrane for gas separation. The thickness of the poly(4-methylpentene-1) thin film was about 0.02μ. Table 1 shows the results of measuring the oxygen permeation rate and oxygen/nitrogen separation coefficient of this composite membrane for gas separation. It can be seen that the composite membrane for gas separation in which the polyorganosiloxane silphenylene copolymer thin film prepared in Example 1 was interposed was not inferior in terms of gas permeability.

Comparative Example 2 A 0.5 wt% solution of polyphenylene oxide prepared in Example 2 in benzene is spread on a water surface to form a thin film, and the thin film is supported on a fluorine porous support membrane to prepare a composite membrane for gas separation. The thickness of the polyphenylene oxide thin film was approximately 0.04 μm. Table 1 shows the results of measuring the oxygen permeation rate and oxygen/nitrogen separation coefficient of this composite membrane for gas separation. It can be seen that the composite membrane for gas separation in which the polyorganosiloxane silphenylene copolymer thin film prepared in Example 2 was interposed was not inferior in terms of gas permeability.

Comparative Example 6 After contacting the thin film surface of the gas separation composite membrane prepared in Comparative Example 1 with a hexafluorine porous support membrane at a pressure of 2 g/- and peeling it off,
The oxygen permeation rate and the separation coefficient between oxygen and nitrogen were measured and the results are shown in Table 2.

Comparative Example 4 The gas separation composite membrane prepared in Comparative Example 2 was subjected to the same adhesion test as in Comparative Example, and the results are shown in Table 2.

Comparative example 3. It can be seen that in Comparative Example 4, the gas separation composite membrane in which the polyorganosiloxane silphenylene copolymer thin film is not interposed has poor adhesion and a loss of separation performance.

As is clear from Section 2, the thin film layer of the present invention is difficult to peel off from the porous support, so it is easy to handle and has good gas permeability.
It can be seen that the gas separation property is excellent.

Table 1 *1Qc,: Oxygen permeation rate (nn'7 m' o hr
aatm ) *2 Qu,; Nitrogen permeation rate (m'/m'
o hr-atm ) * filter α : Separation coefficient Table 2 [Effects of the invention] The gas separation composite membrane of the present invention has a porous support A.

Between the ultra-thin membrane B made of a polymer with high gas separation,
Since the ultrathin film C made of the polyorganosiloxane silphenylene copolymer is interposed, excellent effects such as zero order can be obtained due to the excellent adhesiveness and gas permeability of the polyorganosiloxane silphenylene copolymer.

(]] Composite membranes do not peel off when used, so
Excellent handling properties.

(2) Both gas separation performance and gas permeation performance are excellent.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] Between the porous support A and the ultra-thin membrane B made of a polymer having high gas separation properties, the structural formula is: A gas separation composite membrane comprising an ultra-thin membrane C made of a polyorganosiloxane silphenylene copolymer represented by: