JP2506917B2 - Porous support and gas separation composite membrane using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a porous support and a gas separation composite membrane suitable for separating and concentrating a mixed gas.

2. Description of the Related Art In recent years, many composite membranes for gas separation using organic polymers have been proposed. For example, if oxygen in the air can be separated and concentrated inexpensively by this method, combustion, ironmaking, ceramics,
It is expected that it will contribute greatly to the fields related to waste treatment and health equipment.

These gas separation composite membranes are generally composed of a polymer membrane capable of separating and concentrating and a porous support carrying the polymer membrane. As one method for obtaining such a composite membrane, a solvent is used. There is a method in which a polymer dissolved in water is spread on the surface of water to form an ultrathin polymer film, which is supported on a porous support (eg, JP-A-56-92926).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in this method, even if a composite film is formed,
Depending on the surface condition of the porous support, the adhesion to the polymer film is weak, and the adhesiveness at the interface between the porous support and the polymer film is reduced in a reliability test such as moisture resistance. It has become clear that there is a problem that performance will be reduced faster.

In view of the above problems, the inventors of the present invention have conducted an examination focusing on the surface of the porous support, and found that the adhesiveness with the polymer film changes depending on the surface state of the porous support, and the ultrathin polymer It was possible to obtain a porous support having good adhesiveness to a polymer film and a highly reliable composite film by a water surface expansion method capable of forming a film.

Means for Solving the Problems The porous support of the present invention is a pure support prepared by cutting a porous support cut into a size of 5 cm square for 6 hours or more in a temperature and humidity condition at a test site and keeping the temperature at 20 ° C. The surface of the porous support is immersed for 2 seconds in the surface of distilled water to form a state in which water adheres to the entire surface of the porous support, and immediately after that, the surface of the porous support is taken out from the surface of the water, and the water remains porous on the horizontal surface. It has a surface in which the time from the surface of the support to the immobilization is 30 seconds or less.

Further, the composite membrane for gas separation of the present invention uses the above porous support, and the mixture of the fumaric acid ester copolymer and the polydimethylsiloxane or the polydimethylsiloxane copolymer is used by the porous support. The polymer membrane composed of is supported.

Action With this configuration, if the porous support is cut into 5 cm square dimensions and has a surface with a measured time of 30 seconds or less, the adhesiveness with the ultrathin polymer film obtained by the water surface expansion method is improved. In addition, the composite film has excellent reliability.

Examples Hereinafter, the present invention will be described 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 on a glass substrate to a thickness of 50 μm, and after 2 seconds, poured into a water coagulation bath. Then the temperature 40
After washing with water at 0 ° 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 site for 6 hours, then immersed in the surface of pure water at a temperature of 20 ° C. for 2 seconds, and then gently placed on a horizontal surface. It was 16 seconds when the time required for water to stop moving from the surface of the porous support was measured.

Furthermore, the mixing ratio of the copolymer of polyfumarate and vinyl acetate (manufactured by NOF CORPORATION) and polydimethylsiloxane (“SH-410” manufactured by Toray Silicone Co., Ltd.) is as high as 1: 1 by weight. The molecules were spread on the water surface to form an ultrathin polymer film. When the porous support was gently placed on top of this so that its principal surface was in contact, and pulled up, a composite film with good adhesiveness was obtained. Further, a polymer film was laminated on 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. Note that the measurement conditions are 11.2 cm ² of the membrane area, and the pressure was 1.0 kgf / cm ^2.

This composite film was put in a humidity resistant tank whose temperature was kept at 60 ° C. and relative humidity of 95% and left for 1000 hours to test its reliability. As a result, it was confirmed that the rate of change in the amount of oxygen permeation was −10% of the value before the test, no change was observed in the separation ratio, and 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 to prepare a 20% by weight solution having the same composition as in Example 1. This solution was cast on a glass substrate to a thickness of 50 μm, and after 15 seconds, poured into a coagulation bath of water. Hereinafter, a porous support was prepared under the same conditions as in Example 1.

The test piece of the porous support thus obtained was measured by the same method as in Example 1, and it was found that the time until the water stopped from the surface of the porous support was 50 seconds.

When this porous support was used, it was placed on a polymer film having the same composition as that used in Example 1 and then pulled up,
A partially bubbled composite film was obtained, which was further laminated after the bubbles were gone.

The oxygen permeation second of this composite membrane was 1.21 cc / sec, and the separation ratio of oxygen and nitrogen was 2.78. Note that the measurement conditions are 11.2 cm ² of the membrane area, and the pressure was 1.0 kgf / cm ^2.

When a reliability test was conducted on this composite membrane under the same conditions as in Example 1, the performance after being left for 1000 hours was such that the oxygen permeation amount was −40% of the initial value and the separation ratio was changed to 2.68. .

Example 2 Instead of the glass substrate used in Example 1, polypropylene non-woven fabric was used, and the polyether sulfone solution of Example 1 was applied thereon so that the thickness was 60 μm. Two seconds later, the water was poured into a coagulation bath. Then 1 with water at a temperature of 40 ℃
After washing with water for a period of time, vacuum drying was carried out 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 by the same method as in Example 1, it was 27 seconds.

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

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

When a reliability test was performed under the same conditions as in Example 1, the performance after leaving for 1000 hours was excellent, with a change rate of the oxygen permeation amount from the initial value of -12% and a separation ratio of 2.77, which was almost unchanged. It was a thing.

Comparative Example 2 A porous support integrated with a non-woven fabric was obtained under the same conditions as in Example 2 except that the time of charging into the coagulation tank was changed to 15 seconds.

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

Then, when this porous support was gently placed on a polymer film having the same composition as in Example 1 and pulled up, a composite film having bubbles, which was considered to have weak adhesiveness, was obtained. When the bubbles disappeared, a polymer film was further laminated thereon.

The composite membrane thus obtained had an oxygen transmission time of 1.20.
It was cc / sec and the separation ratio of 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 with respect to the initial value was -50%, and the separation ratio was 2.70.

Example 3 The material of polysulfone was used in place of the polyether sulfone in Example 1, and a 20% by weight dimethylformamide solution was prepared.
It was applied to a thickness of m, and after 2 seconds, it was put into 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 by the same method as in Example 1, it was 21 seconds.

Next, a polymer prepared by using a polysulfone-polyhydroxystyrene-polydimethylsiloxane copolymer instead of the polydimethylsiloxane used in Example 1 and mixing the polyfumaric acid copolymer at a ratio of 1: 1. Was spread on the water surface to form an ultrathin polymer film. When the porous support was gently placed on top of this so that its surface was in contact, and pulled up, a composite film with good adhesiveness was obtained. Further, a polymer film was laminated on this.

The oxygen permeation seconds of the composite membrane thus obtained were 1.02
It was cc / sec, and the separation ratio of oxygen and nitrogen was 2.82.

When a reliability test against moisture was conducted in the same manner as in Example 1, the performance after being left for 1000 hours was stable, with a rate of change in oxygen permeation amount from the initial value of −10% and a separation ratio of 2.80. It was confirmed to show performance.

Comparative Example 3 Example 3 except that the water coagulation bath was charged after 20 seconds.
A porous support was obtained under the same conditions as above. When the surface of this porous support was measured by the same method as in Example 1, it was 62 seconds.

Using this porous support, it was gently placed on a polymer film having the same composition as in Example 3 and pulled up. As a result, the polymer film partially remained on the water surface, and a composite film could not be obtained. .

As is clear from the examples of the present invention and comparative examples thereof, the porous support cut out into a size of 5 cm square was left at a temperature and humidity of the test place for 6 hours or longer, and purified water or distillation kept at a temperature of 20 ° C. On the water surface of water, the surface of the porous support is immersed for 2 seconds to form a state in which water is attached to the entire surface of the porous support, and immediately after that, the water is taken out from the water, and the water is left stationary on a horizontal surface. If the time from the surface of the porous support to the immobilization time is 30 seconds or less, it is possible to obtain a porous support that has good adhesion to the polymer membrane and that has excellent properties even in a reliability test with humidity resistance. You can If the time is less than 30 seconds for a 5 cm square porous support, the adhesion between the porous support and the polymer membrane will be weak and the performance of the composite membrane will be accelerated, which is not preferable.

The porous support material is not limited to the material used in the above examples.

EFFECT OF THE INVENTION The porous support of the present invention is prepared by cutting the porous support cut into 5 cm pieces at 20 ° C. for 6 hours or more under the temperature and humidity conditions of the test site.
The surface of the porous support was immersed for 2 seconds on the surface of pure water maintained at the temperature of 2 to form a state in which water was attached to the surface of the porous support, and immediately after that, the porous support was taken out and rested on a horizontal surface. Since the surface of the porous support has a time of 30 seconds or less until the water does not move from the surface of the porous support, the adhesiveness to the polymer membrane is excellent. The composite membrane using this porous support exhibits excellent performance in a moisture resistance reliability test.

Claims (2)

(57) [Claims] 1. A porous support cut into a size of 5 cm square is left at a temperature of 20 ° C. for 6 hours or more in a temperature and humidity condition of a test place.
The surface of the porous support is immersed for 2 seconds in the surface of pure water or distilled water held in the above to form a state in which water adheres to the entire surface of the porous support, and then immediately taken out from the water and placed on a horizontal surface. A porous support having a surface in which the time for which water does not move from the surface of the porous support in a stationary state is 30 seconds or less. 2. The porous support according to claim 1,
A composite membrane for gas separation, characterized in that a polymer membrane composed of a fumaric acid ester copolymer and polydimethylsiloxane or a mixture of polydimethylsiloxane is supported.