JPS5962303A - Oxygen separating and enriching membrane - Google Patents

Abstract

PURPOSE:To provide a titled composite membrane which possesses and can sustain various performances such as O2 separating performance and the rate of air permeation, etc. as well as strength by forming the same by laminating in specific order the films consisting of fluoropolymers modified with respectively different specific contents of siloxane. CONSTITUTION:A titled O2 separating and enriching membrane is formed by laminating a film consisting of a fluoropolymer highly modified with siloxane on a porous backing film, and further laminating a film consisting of a fluoropolymer slightly modified with siloxane thereon. The silicon contents of the fluoropolymers modified highly and slightly with siloxanes in this case are adequately 50-99% and 1-50% respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an oxygen separation and enrichment membrane, particularly a high oxygen separation and enrichment property,
The air permeation rate is high, and the composite membrane is capable of sustaining these performances.

Oxygen-enriched air with an oxygen concentration of 30 to 50% is required, for example, for blast furnace ventilation, combustion auxiliary agents, petroleum protein processing, waste liquid treatment, exhaled air in medical care, and the like. Conventionally, oxygen-enriched air has been obtained by producing high-purity oxygen through cryogenic liquefaction distillation and then mixing with air to obtain the desired oxygen concentration.

However, in such a method, since high-purity oxygen is generally contained in a pressure vessel, there are risks in handling the pressure vessel or the need for a pressure regulator to keep the mixed gas concentration constant.
There were various problems such as the complexity of the operation.

On the other hand, as a method of obtaining 30-50% oxygen enriched air,
There is a membrane separation method.

This method provides direct oxygen-enriched air, is operationally simple, and is economically advantageous.

Several proposals have been made for such separation membranes, such as organopolysiloxane-polycarbonate copolymers.

However, although some of these conventionally proposed products have fairly good performance in themselves, they are difficult to handle due to strength issues and difficulty in handling.
It may be used in some cases.

In such cases, the performance often deteriorates or the sustainability of the performance deteriorates significantly, depending on the properties of the other membrane to which it is combined or the properties of the oxygen-enriching membrane itself. In particular, when attempting to obtain a high-separation composite membrane in which an ultra-thin membrane of separation membrane material is laminated on a porous support membrane, it is difficult to obtain the desired separation performance due to membrane defects (pinholes). In view of these points, the membrane has sufficient performance such as oxygen separation performance and a predetermined air permeation rate required by an oxygen enrichment membrane, is strong enough to withstand use, and can last for a long period of time. As a result of various studies and examinations aimed at obtaining a composite membrane, the above objective was achieved by laminating membranes made of fluorine-containing polymers modified with different specific siloxanes in a specific order on a porous support. I found out what can be achieved.

Thus, the present invention provides an oxygen separation and enrichment membrane comprising a membrane made of a high siloxane modified fluorine-containing polymer laminated on a porous support membrane, and a membrane made of a low siloxane modified fluorine containing polymer further laminated thereon. It is in.

The porous support membrane used in the present invention has physical properties such as an average pore diameter of 10 to 2000λ and a porosity of 10 to 90.
It is appropriate to have %.

If these physical properties deviate from the above ranges, it is difficult to obtain a sufficient oxygen permeation rate, and defects are likely to occur when laminating an ultra-thin film on a support film, which is not preferable.

Examples of the material for such a film include polysulfone, polyamide, polyacrylonitrile, polyethylene, polyvinyl alcohol, and polytetrafluoroethylene. Further, it is appropriate that the siloxane content in the high siloxane modified fluorine-containing polymer used is 50 to 99. If the needle content exceeds the above range, oxygen-
This is not preferable because the overspeed becomes insufficient.

Of these ranges, a fit of 60 to 8 degrees is particularly preferred because it provides a sufficient oxygen permeation rate and a thin film with sufficient strength for long-term durability. Further, examples of the high silicon modified fluorine-containing polymer include a graft copolymer of polysiloxane and a fluoroolefin/olefin copolymer, a graft copolymer of polysiloxane and a fluoroolefin/vinyl ether copolymer, etc. I can do it. Examples of fluoroolefins include tetrafluoroethylene, trifluorochloroethylene, and vinylidene fluoride; examples of olefins include ethylene, propylene, and 1-butylene; and examples of vinyl ethers include ethyl vinyl ether, phthyl vinyl ether,
Examples include killing cyclohegycyl vinyl ether. Each of these polysiloxanes and fluorine-containing copolymers must have a reactive site.

There are no particular restrictions on the method for forming the lining of these siloxane-modified fluorine-containing polymers, and examples include block copolymerization of organosiloxane monomer and fluorine-containing monomer Q, blending organopolysiloxane and fluorine-containing copolymer, and combining both. Methods such as graft copolymerization by polymer reaction can be employed via the reaction sites included. 6.Means for producing membranes using such polymers include methods such as ultrafiltration, coating, and water gearing. The ultrafiltration coating method is preferably used as the film forming method since it is important that the composite film has virtually no pinholes.

The thickness of such a film is generally 0.05 to 10γ,
Preferably, it is appropriate to adopt α1 to 5γ.

Next, a film made of a low-silicon modified fluorine-containing polymer is laminated on the layer, and it is appropriate that the low-silicon modified fluorine-containing polymer has a total silicon content of 1 to 50%. . If the content exceeds the above range, it is not preferable because the selectivity of oxygen permeation of the membrane decreases. Among these ranges, it is particularly preferable to use a ratio of 10 to 50 because sufficient oxygen selectivity can be obtained and the oxygen permeation rate can also be improved. As the low siloxane modified fluorine-containing polymer, the same polymer as the above-mentioned high siloxane modified fluorine-containing polymer can be used.

Further, as a means for producing m= using such a polymer, this is also produced in accordance with the above-mentioned method for forming a film from a high-silicon modified fluorine-containing polymer.

The thickness of the film obtained from such a low siloxane modified fluorine-containing polymer is generally 100 to 2000, preferably 3.
It is appropriate to adopt a value of 00 to 1000.

Thus, as a means of actually manufacturing a composite membrane using these materials, for example, to form a film of a high-silicone modified fluorine-containing polymer, a high silicone modified fluorine-containing polymer is added in a solvent that does not dissolve the supporting film in an amount of 1 to 3% by heavy acid. A method in which the dissolved solution is subjected to ultrafiltration using an ultrafiltration membrane (support membrane), or a method of forming a film of a low silicone modified fluorine containing polymer by dissolving several percent of the low silicone modified fluorine containing polymer in a solvent that is insoluble or has little solubility in water. However, a method such as an above-water casting method, in which both films can be obtained by dropping this solution onto the water surface, can be employed.

By combining the wooden removal method, the desired layered oxygen-enriched membrane can be formed.

Next, all embodiments of the present invention will be explained.

Example 1 E The molar ratio of fluorinated monochloroethylene/cyclohexyl vinyl ether/ether vinyl ether/glycidyl vinyl ether is 50/15/32.5/2.5
and the number average degree of polymerization is 6oo.
25 of trifluorotrichloroethane 7 (R-113)
18Z5 of a solution of R-113 containing 37.59% of an amino group-containing organopolysiloxane having a composition having a number average degree of polymerization of about 5000 is added dropwise to the bath solution. Stirring is continued for about 2 hours after the completion of the dropwise addition. Temperature 47℃
The reaction was carried out for 1 hour while the solvent was evaporated and concentrated. Further, the mixture is heated to 80° C. and the reaction is continued for 1.5 hours under reduced pressure.

The obtained polymer was a graft copolymer containing 40% by weight of the polysiloxaf F and 60% by weight of fluorine-containing interlocking segments. The gas permeation performance of this graft copolymer through a film obtained by dissolving this graft copolymer 42 in 12 ml of ethyl acetate and casting it on a glass plate is as follows: oxygen permeability coefficient o, 6 x 101 (L-cm /
ar? ,5txtynH9,m element.

The nitrogen separation coefficient α was 4.8.

Example 2 The graft copolymer (polysiloxane segment-containing 4 (37, F 8%)) obtained in Example 1 was converted into R-
11! Dissolve under stirring in 1509 liters.

A solution prepared by dissolving amino-containing organopolysiloxane 212 similar to that used in Example 1 in R-113 849 is added dropwise to this solution to obtain a uniform mixed solution. The mixed solution was reacted in the same manner as in Example 1 to obtain a graft copolymer containing V75-i polysiloxane segments.

Gas permeability of the graft copolymer Oxygen permeability coefficient 2
X 1' 0-8C0-8C/1ri-hiro・tynH9
, the separation coefficient Po2/PN2 was 2.5.

Example 3 Polysiloxane segment content 75 obtained in Example 2
% by weight of graft copolymer 01o2 to 150Of R-
113 and filtered using a polysulfone ultrafiltration membrane under a filtration pressure of 21 (Li/crl G). When the filtration is completed, the membrane is removed from the pressurized filter and dried. , a composite film of highly silicone-modified fluorine-containing polymer was obtained.The film thickness of the thin film formed on the porous support film was
Calculated from l kt, Q was 7γ.

Next, the graft copolymer 12 containing the polysiloxane segment obtained in Example 1 and containing μ40 pupil % was added to R-113-5.
Dissolves in a8f. A few drops of the solution were spread on the surface of the water to obtain a cast film. Two cast thin films of the low silicone-modified fluorine-containing polymer formed on water were collected by stacking them on the composite film of the high-silicone modified fluorine-containing polymer to obtain a laminated composite film. The gas permeability of the laminated composite membrane was measured by a reduced pressure method. The measurement threads are shown in the table below.

Example 4 0.069 of the polysiloxane segment-containing 5tfff 1% graft copolymer obtained in Example 2 was
．． The solution was dissolved in R-113 of Example 5.
Ultrafiltration was performed in the same manner as above to obtain composite HIA'f. Calculated from the thin film formed on the porous support membrane: 04μ
Met.

Next, in the same manner as in Example 3, low silicone-modified fluorine-containing polymers were laminated by a water casting method (by hand) to obtain a laminated composite film.

The measurement results of gas permeability are shown in the table.

Comparative Example 1 Polysiloxane segment impregnation 75 obtained in Example 2
Weight q% of graft copolymer Q, 07r to 15009R
-113 and filtered it using an ultrafiltration membrane made of polysulfone at a filtration pressure of 2 Kg/JQ/III
Passes offshore under pressure. Once filtration is complete, remove the membrane from the pressurized P1 container, dry it, and use high silicone-modified fluorine-containing polyester! The gas permeability of the composite membrane was measured. The measurement results are shown in the table as a comparative example.

Comparative Example 2 Polysiloxane segment-containing tit obtained in Example 1
B-113', 404j amount % of graft copolymer 1f,
Dissolves in 58.82. Place a few drops of sweat solution on the surface of the water.
was expanded to obtain a casting thin film. Then, the casting thin film was placed on an ultrafiltration membrane made of polysulfone for 5 minutes.
They were collected in layers to obtain a composite membrane made only of low silicone-modified fluorine-containing polymer.

The table shows the optical transmission performance as a comparative example.

Claims (1)

[Claims] 1. Oxygen separation and enrichment comprising laminating a membrane made of a high-siloxane modified fluorine-containing polymer on a porous support membrane, and further laminating a membrane made of a low-siloxane modified fluorine-containing polymer thereon. film. 2. The porous support membrane has an average pore diameter of 10~2000^
, a porosity of 10 to 90%. 3. The porous support membrane is polysulfone, polyamide, polyacrylonitrile, polyethylene, polyvinyl alcohol, polytetrafluoroethylene.
1) or ]2) membrane. 4. The film according to claim (1), wherein the high 70 Gisan modified fluorine-containing polymer has a silicon content M of 50 to 99. 5. The membrane according to claim (1) or (4), wherein the high siloxane modified fluorine-containing polymer is a copolymer consisting of an organopolysiloxane segment and a fluorine-containing polymerized segment. 6. The low-siloxane-modified fluorine-containing polymer has a silicon content of 1 to 50. 7. The low-siloxane-modified fluorine-containing polymer has a silicon content of 1 to 50. The membrane according to claim (1) or (6), which is a polymer.