JPH01245036A - Cellular support and gas separation composite membrane using said support - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a porous support and a mixed gas in a molecular i! The present invention relates to a composite membrane for gas separation suitable for concentration.

Conventional technology In recent years, many composite membranes for gas separation using organic polymers have been proposed. It is expected that it will make a significant contribution to the fields of material processing and health equipment.

These gas separation composite membranes are generally composed of a polymer membrane that can be subjected to minute contraction and a porous support supporting the polymer membrane, and one method for obtaining such a composite membrane is to A polymer dissolved in a solvent is spread on the water surface,
There is a method of forming an extremely thin polymer membrane and supporting it on a porous support (eg, Japanese Patent Laid-Open No. 56-92926).

Problems to be Solved by the Invention However, with this method, even if a composite membrane is formed, depending on the surface condition of the porous support, the adhesion with the polymer membrane may be weak (and reliability tests such as moisture resistance may be difficult). It has become clear that there is a problem in that the performance of the composite membrane deteriorates more quickly due to decreased adhesion at the interface between the porous support and the polymer membrane.

In view of the above issues, the inventors focused on the surface of the porous support and found that the adhesion with the polymer membrane changes depending on the surface condition of the porous support. A porous support with good adhesion to the polymer membrane was obtained using a water surface development method that allows the membrane to be formed, and a highly reliable composite membrane was also obtained.

Means for Solving the Problems The porous support of the present invention is prepared by cutting out a porous support into a size of 5 cm square, leaving it in the temperature and humidity conditions of a test site for 6 hours or more, and then soaking it in pure water or water maintained at a temperature of 20°C. The surface of the porous support is immersed in the surface of distilled water for 2 seconds to form a state in which water is attached to the entire surface of the porous support, and then immediately taken out from the water surface and left standing still on a horizontal surface until the water becomes porous. It has a surface that takes 30 seconds or less to stop moving from the support surface.

Further, the composite membrane for gas separation of the present invention uses the porous support described above, and uses the porous support to form a mixture of a copolymer of fumaric acid ester and polydimethylsiloxane or a copolymer of polydimethylsiloxane. A polymer membrane composed of is supported.

Function: With this configuration, if the porous support is cut into a 5CI11 square size and has a surface whose measurement time is 30 seconds or less, the adhesiveness with the ultra-thin polymer membrane obtained by the water surface development method is good. This results in a composite membrane with excellent reliability.

EXAMPLES Hereinafter, the present invention will be explained based on Examples and Comparative Examples.

Example 1 100 parts by weight of polyether sulfone was dissolved in 400 parts by weight of dimethylformamide to prepare a 20% by weight solution. This solution was cast onto a glass substrate to a thickness of 50 μm, and after 2 seconds it was poured into a water coagulation bath. after that,
After washing with water at a temperature of 40°C for 1 hour, vacuum drying was performed at a temperature of 60°C for 30 minutes to obtain a porous support.

A 5 cm square sample was cut out from this porous support, left at the test location for 6 hours, the surface of the porous support was immersed in pure water at a temperature of 20°C for 2 seconds, and then gently placed on a horizontal surface. The time required for water to stop moving from the surface of the porous support was measured and was found to be 16 seconds.

Furthermore, the mixing ratio of a copolymer of polyfumaric acid ester and vinyl acetate (manufactured by NOF Corporation) and polydimethylsiloxane (rSH-410J, manufactured by Toray Silicone Co., Ltd.) was 1=1 by weight. It was spread on the water surface to form an ultra-thin polymer film. When the porous support was gently placed on top of the support so that its main surface was in contact with the support and pulled up, a composite film with good adhesion was obtained. moreover,
A polymer membrane was laminated on top of it.

The oxygen permeation rate of this composite membrane was 1.20 cc/sec, and the separation ratio of oxygen and nitrogen was 2.80. The measurement conditions are: membrane area of 11.2cnf, pressure of 1,000 kg.
f/cnf.

This composite membrane was placed in a moisture-resistant tank maintained at a temperature of 60° C. and a relative humidity of 95%, and left for 1000 hours to test its reliability. As a result, the rate of change in the amount of oxygen permeation was 10% of the value before the test, and no change was observed in the separation ratio, confirming that it had very excellent reliability.

Comparative Example 1 100 parts by weight of polyether sulfone was dissolved in 400 parts by weight of dimethylformamide, and 2
A 0% by weight solution was prepared. This solution was cast onto a glass substrate to a thickness of 50 μm, and 15 seconds later, it was poured into a water coagulation bath.

Hereinafter, a porous support was produced under the same conditions as in Example 1.

The test piece of the porous support thus obtained was measured in the same manner as in Example 1, and the time required for water to stop moving from the surface of the porous support was 50 seconds.

When this porous support was placed on a polymer membrane with the same composition as that used in Example 1 and pulled up, a composite membrane with some bubbles was obtained, and after the bubbles disappeared, More layers were added.

The oxygen permeation rate of this composite membrane is 1.21 cc/sec,
The separation ratio between oxygen and nitrogen was 2.78. The measurement conditions were such that the membrane area was 11.2cI11. Pressure 1,0
It was set to 1 ps f/cdl.

When this composite membrane was subjected to a reliability test under the same conditions as in Example 1, the performance after being left for 1000 hours was -40% of the initial value of the amount of WI element passing through.

The separation ratio had changed to 2.68.

Example 2 A polypropylene nonwoven fabric was used in place of the glass substrate used in Example 1, and the polyethersulfone solution of Example 1 was coated onto it to a thickness of 60 μm. After 2 seconds, it was poured into a water coagulation bath. Thereafter, it was washed with water at a temperature of 40°C for 1 hour, and then vacuum dried at a temperature of 60°C for 30 minutes to obtain a porous support integrated with the nonwoven fabric.

When the surface condition of the porous support was measured in the same manner as in Example 1, it was 27 seconds.

Furthermore, when the surface of this porous support was gently placed on a polymer membrane having the same composition as in Example 1 and pulled up, a composite membrane with good adhesiveness was obtained. Furthermore, a polymer membrane was laminated on top of that.

The oxygen permeation rate of this composite membrane was 1.18 cc/sec, and the separation ratio of oxygen and nitrogen was 2.78.

A reliability test was conducted under the same conditions as in Example 1, and the performance after 1,000 hours of storage showed that the rate of change in oxygen permeation from the initial value was 112%, and the separation ratio was 2.77, showing almost no change. , it was excellent.

Comparative Example 2 A porous support integrated with a nonwoven fabric was obtained under the same conditions as in Example 2, except that the time to put it into the coagulation bath was changed to 15 seconds later.

When the surface condition of this porous support was measured using the same method as in Example 1, it was found to be 45 seconds.

When this porous support was gently placed on a polymer membrane having the same composition as in Example 1 and pulled up, a composite membrane with bubbles that appeared to have weak adhesion was obtained. When the bubbles disappeared, a polymer membrane was further laminated on top of the bubbles.

The oxygen permeation time of the composite membrane thus obtained was 1.2
The rate was 0 cc/sec, and the separation ratio between oxygen and nitrogen was 2.76.

This composite membrane was subjected to a reliability test under the same conditions as in Example 1, and after being left for 1000 hours, the rate of change in oxygen permeation seconds relative to the initial value was 150%, and the separation ratio was 2.70. .

Example 3 Using a polysulfone material in place of the polyethersulfone in Example 1, a 20% by weight dimethylformamide solution was prepared, and a solution of 60% by weight was prepared on a polypropylene nonwoven fabric.
It was coated to a thickness of μm, and after 2 seconds it was placed in a water coagulation bath. Then, it was washed with water at a temperature of 40°C for 1 hour and vacuum dried at a temperature of 60°C for 30 minutes to obtain a porous support integrated with the nonwoven fabric.

When the surface of the porous support was measured in the same manner as in Example 1, it was 21 seconds.

Next, a copolymer of polysulfone-polyhydroxystyrene-polydimethylsiloxane was used in place of the polydimethylsiloxane used in Example 1, and a polymer was mixed in a ratio of 1:1 with the polyfumaric acid copolymer. was spread on the water surface to form an ultra-thin polymer film. A porous support was gently placed on top of this so that its surfaces were in contact with each other, and when pulled up, a composite membrane with good adhesion was obtained. Furthermore, a polymer membrane was laminated on top of this.

The oxygen permeation time of the composite membrane thus obtained is 1,
02cc/sec, and the separation ratio between oxygen and nitrogen is 2.82
Met.

A humidity reliability test was conducted in the same manner as in Example 1, and the performance after being left for 1000 hours was as follows: The rate of change in oxygen permeation amount relative to the initial value was 110%, and the separation ratio was 2.80.
It was confirmed that it exhibited stable performance.

Comparative Example 3 Example 3 except that the water was added to the water coagulation bath 20 seconds later.
A porous support was obtained under the same conditions. When the surface of this porous support was measured in the same manner as in Example 1, it was 62 seconds.

When this porous support was gently placed on a polymer membrane with the same composition as in Example 3 and pulled up, the polymer membrane remained partially on the water surface, and a composite membrane could not be obtained. .

As is clear from the examples of the present invention and its comparative examples, a porous support cut into a size of 5cn+square was left in the temperature and humidity conditions of the test site for 6 hours or more, and purified water or The surface of the porous support is immersed on the surface of distilled water for 2 seconds to form a state in which water is attached to the entire surface of the porous support, and then immediately removed from the water,
If water does not move from the surface of the porous support when it is stationary on a horizontal surface (30 seconds or less), the adhesion with the polymer membrane is good, and it also excels in moisture resistance reliability tests. A porous support with similar characteristics can be obtained.5
If the above-mentioned time is less than 30 seconds for a c+m square porous support, the adhesion between the porous support and the polymer membrane will be weak and the performance of the composite membrane will deteriorate more quickly.

Undesirable.

Note that the porous support material is not limited to the materials used in the above examples.

Effects of the Invention The porous support of the present invention is obtained by leaving a porous support cut into 5 cm pieces under the temperature and humidity conditions of a test location for 6 hours or more,
The surface of the porous support was immersed for 2 seconds on the surface of pure water maintained at a temperature of ℃ to form a state in which water adhered to the surface of the porous support, and then immediately taken out and placed on a horizontal surface. Since the porous support has a surface in which it takes 30 seconds or less for water to stop moving from the surface of the porous support in this state, it has good adhesion to the polymer membrane. A composite membrane using this porous support exhibits excellent performance in moisture resistance reliability tests.

Claims (2)

[Claims] (1) A porous support cut out to a size of 5 cm square was left in the temperature and humidity conditions of the test location for 6 hours or more, and the surface of the porous support was placed on the surface of pure water or distilled water maintained at a temperature of 20°C. is immersed for 2 seconds to form a state in which water is attached to the entire surface of the porous support, and then immediately taken out of the water and kept stationary on a horizontal surface until water stops moving from the surface of the porous support. A porous support having a surface whose time is 30 seconds or less. (2) The porous support according to claim 1 supports a polymer membrane composed of a mixture of a fumaric acid ester copolymer and polydimethylsiloxane or a polydimethylsiloxane copolymer. A composite membrane for gas separation characterized by: