JPH01288315A - Permselective gas permeable membrane - Google Patents

Abstract

PURPOSE:To obtain a permselective gas permeable membrane having high mechanical strength wherein its gas permeation factor and separation factor are well balanced by providing a permselective gas permeable polymer layer between porous substrate layers. CONSTITUTION:Polymer layers having permselective permeability such as silicone, siloxane copolymer, polyphenylene oxide, etc., are provided between porous substrate layers such as polyolefin, cellulose acetate, porous alumina etc., in such a way that a plurality of porous substrats are superposed upon each other with small clearances therebetween impregnated with polymer layer raw material to be dried and solidified, or polymer layer raw material is applied to the surfaces of porous substrata so that the coated surfaces are superposed upon each other to be pressed, dried, and solidified. The permselective gas permeable membranes so obtained have a high mechanical strength and allow oxygen gas etc. to be selectively passed therethrough efficiently, wherein their gas permeation factor and separation factor are well balanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a selective gas permeable membrane and a method for manufacturing the same, and more particularly, to various gas separation membranes for medical use, water treatment and combustion equipment, and biotechnology. The present invention relates to a selective gas permeable membrane that can be suitably used in various fields.

[Prior Art and its Problems] Various methods have been used as gas separation methods for a long time, such as cooling condensation distillation, adsorption separation, and solvent or extraction separation.

However, these commonly adopted methods require a large amount of energy and complicated equipment. Therefore, in recent years, many attempts have been made to reduce energy consumption by performing this gas separation using membranes made of polymeric materials.

In response to such demands, there have been several reports on gas separation methods using separation membranes.

For example, JP-A-48-84199. Japanese Unexamined Patent Publication No. 58-18
According to JP-A-58-14928, etc., an attempt has been made to reduce energy consumption by using a selective gas permeable membrane made of an organosiloxane polymer or the like.

However, in these selective gas permeable membranes, the gas permeability coefficient has not yet reached a sufficient level, and reducing the membrane thickness to increase the gas permeation coefficient only reduces the gas separation coefficient. (1) Problems such as a decrease in mechanical strength and the formation of pinholes occur.

Therefore, in order to solve the above-mentioned inconveniences, we
928, Japanese Patent Publication No. 59-24843, etc., attempts have been made to use a water surface spread membrane of a polymer solution or a plasma polymerized membrane to provide strength with a porous base material and to make the selective gas permeable membrane thinner, but the process for forming a composite membrane is difficult. Not only is it extremely complex, but its mechanical strength is also unsatisfactory.

Furthermore, it is difficult to control the balance between the gas permeability coefficient and the separation coefficient.

The present invention overcomes the disadvantages of conventional selective gas permeable membranes, and provides an easy-to-handle selective gas permeable membrane that has excellent balance between gas permeability coefficient and separation coefficient, and also has mechanical strength. It was made with the purpose of providing.

[Means for Solving the Problems] The structure of the present invention for solving the problems described above is characterized in that a polymer layer having gas selective permeability is provided between the porous base layers. It is a selective gas permeable membrane.

The selective gas permeable membrane of the present invention will be explained in detail below.

As the porous base material, organic or inorganic base materials can be used. For example, organic porous base materials include polyolefins such as polyethylene and polypropylene, and fluorine base materials such as polytetrafluoroethylene. resin,
Examples include cellulose acetate, nitrocellulose, vinyl chloride, polysulfone, polyethersulfone, and acrylate polymers.

On the other hand, examples of the inorganic porous base material include porous silica, porous alumina, and glass fiber membrane.

The average pore diameter of these porous substrates is usually 0.0
Those having pores in the range of 1 to 10 p, m, preferably 0.1 to 5 g, m can be suitably used.

If this average pore diameter is less than 0.01 uL+n.

For example, the permeability (permeability coefficient) of gases such as oxygen gas may be insufficient, and on the other hand, when IOILm is exceeded, the permeability selectivity for gases and oxygen molecules may decrease.

The shape of the porous base material is usually a flat plate or a flat membrane, but due to the design of the selective gas permeable membrane, a plate or membrane with a three-dimensional structure having a curved surface etc. is also used. It can be selected as appropriate.

As the polymer for forming the polymer layer having gas selective permeability, it is possible to employ polymers used in known gas permeable membranes, such as silicone rubber such as polyorganosiloxane, polyorganosiloxane, etc. Siloxane
Polycarbonate copolymer, dimethylsiloxane-α-
Methylstyrene copolymer, α,ω-polysiloxane-phenol resin copolymer, α,ω-diaminoethylpolydimethylsiloxane-polyhydroxystyrene copolymer,
Siloxane-polyurethane copolymer.

Examples include siloxane-polyether copolymer, trisilylpropyne, and polyphenylene oxide.

Note that this polymer layer may be composed of a plurality of thin films of different polymers, or may be a layer of a single type of polymer.

The selective gas permeable membrane may have any layer configuration as long as it includes the polymer layer having gas selective permeability between the porous base layers. To give an example, for example, a layer structure in which one layer of the polymer layer is interposed between a pair of porous base material layers, and a layer structure in which a plurality of the polymer layers are interposed between a pair of porous base material layers. A layer structure in which one or more polymer layers are interposed between each porous base material layer in three or more porous base material layers stacked together, etc. I can do it.

Which layer structure should be adopted may be appropriately determined depending on the balance between the gas permeability coefficient and the separation coefficient, the use of the selective gas permeable membrane, and the like.

Note that the polymer layer may be provided on the outer surface of the porous base material layer constituting the selective gas permeable membrane, as long as the object of the present invention is not impaired.

The thickness of the porous base material layer and the thickness of the polymer layer are also selected in this manner. Although it cannot be determined unconditionally because it varies depending on the use of the selective gas permeable membrane, in many cases, the thickness of the porous base material is lθ to 300p.
m, and the thickness of the polymer layer is 0.01 to 3 m.

Such a selective gas permeable membrane can be manufactured as follows.

For example, ■ multiple layers of porous base materials are stacked together with a slight gap between each base material, i.e., multiple layers of porous base materials are simply stacked one on top of the other, and the raw material for the polymer layer is impregnated, and then dried or solidified. (2) Applying a polymer layer raw material to the surface of a porous substrate, overlapping the coated surfaces, and applying pressure, drying, or solidification.

In both of the production methods (1) and (2) above, the polymer MjX material is a solution of the polymer.

Examples include liquid oligomers or reactive liquid hetamines which yield the above-mentioned polymers through a crosslinking reaction or the like. In addition, when forming a polymer layer, if crosslinking or polymerization by heating is used, the polymer raw material may optionally contain a crosslinking agent, a polymerization accelerator, a molecular weight Additives such as regulators and anti-aging agents and other polymers may also be blended.

When adopting the impregnation method (ii) above, there is no particular restriction on the impregnation method as long as the polymer raw material can be uniformly permeated into each gap of the layered porous substrates, and the impregnation method is not particularly limited. A method may be adopted in which the entire combined porous base material is immersed in the polymer raw material or the like, or a method in which it is partially immersed and one polymer raw material or the like permeates into each gap of the porous base material.

When applying the coating and pressure bonding method described in (2) above, the polymer raw material can be applied to the surface of the porous substrate by a commonly used method such as a spray method. There are no particular restrictions on the method as long as it can uniformly apply the combined raw materials, and there are no particular restrictions on the method of pressure bonding as long as it does not leave air bubbles in the gaps between the base materials.

Next, the process of converting the polymer raw material between the porous base material layers into a polymer layer depends on the type of polymer raw material. Drying treatment, ■ If the polymer raw material contains a polymer and a crosslinking agent, crosslinking treatment in which a crosslinking reaction is caused by heating to a predetermined temperature; If it contains a sensitizer, examples include polymerization treatment or crosslinking treatment in which a polymerization reaction is caused by heating, light irradiation, electron beam irradiation, etc.

As the drying treatment in (2) above, a known drying method can be employed, such as a heating drying method, a hot air drying method, a reduced pressure drying method, and the like.

The heating conditions for the heat treatment method are usually 50 to 15
Heating at 0°C for 10 to 30 minutes is suitable.

In addition, when a solvent is used for the impregnation treatment, the heat treatment may be performed after removing the solvent by evaporation or the like.
The heat treatment may be performed in the presence of a solvent.

The polymerization treatment or the crosslinking treatment method in (1) or (@) is a conventionally used method.

For example, a heat treatment method, an ultraviolet irradiation method, an electron beam irradiation method, etc. can be used.

The heating conditions for the heat treatment method are usually 50 to 15
Heating at 0°C for 5 to 120 minutes is suitable.

In addition, in the case of ultraviolet irradiation, it is preferable to treat with a photosensitizer such as quinones and irradiate with ultraviolet rays at 20 to 100° C. for 2 to 120 minutes using a high-pressure mercury lamp or the like.

In addition, when a solvent is used for the impregnation treatment, the heat treatment may be performed after removing the solvent by evaporation or the like.
The heat treatment may be performed in the presence of a solvent.

[Example] (Porous polypropylene (pore diameter 0.04 pm, thickness 30 g)
Two sheets of m) were stacked together, and an n-hexane solution (silicone concentration; 6 g/100
mu) and dried to obtain a selective gas permeable membrane.
The weight gain was approximately 40% of the substrate.

Using the obtained selective gas permeable membrane, the pressure method (differential pressure 0.
5 kg/cm2), the membrane properties such as oxygen gas and nitrogen gas permeability and separation coefficient were determined.

The results are shown in Table 1.

In addition, the separation coefficient α is calculated using the formula Calculated by.

(Example 2) Two porous substrates similar to those used in Example 1 were stacked together, and a toluene solution (silicone Wi ; 12g/100m!L) impregnated,
A selective gas permeable membrane was obtained by drying.

The rf1 tatami increase was about 60% of the base material. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

(Example 3) Porous Teflon (pore diameter 0.85 JL m, thickness 50p
Two sheets of siloxane m) are stacked on top of each other and a mixture of liquid siloxane oligomers (siloxane containing a functional group -9iH and -
A selective gas permeable membrane was obtained by impregnating the membrane with siloxane containing CH=CH2 (mixed at a functional group ratio of 1:1) and crosslinking by heating at 70° C. for 2 hours.

The weight gain was approximately BO% of the substrate. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

(Example 4) Three sheets of porous Teflon (pore diameter: 0.85 pm, thickness: 50 gm) were stacked together, impregnated with the same liquid siloxane oligomer mixture as in Example 3, and heated and crosslinked at 70°C for 2 hours. A selective gas permeable membrane was obtained.

The weight gain was about 65% of the substrate. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 1) One porous substrate similar to that used in Example 1 was impregnated with the same polymer raw material as used in Example 1, and dried to obtain a selective gas permeable membrane. Ta.

The weight gain was approximately 40% of the substrate. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 2) A porous substrate similar to that used in Example 1 was impregnated with the same polymer raw material as used in Example 2, and dried to obtain a selective gas permeable membrane. Ta.

The weight gain was approximately 70% of the substrate. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 3) A porous substrate similar to that used in Example 3 was impregnated with the same polymer raw material as used in Example 3, and dried to obtain a selective gas permeable membrane. The weight increase is approximately 85% of the base material.
Met. The film properties were determined in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 [Effects of the Invention] The selective gas permeation membrane according to the present invention has an excellent balance between the gas permeation coefficient and the separation coefficient, and therefore can efficiently selectively permeate gases such as oxygen gas. Moreover, since a polymer layer having gas selective permeability is provided in the space of the porous base material layer serving as a support, mechanical strength can be increased. Furthermore, the selective gas permeable membrane can be manufactured through extremely simple steps.

Claims (1)

[Claims] (1) A selective gas permeable membrane comprising a polymer layer having gas selective permeability between porous base layers.