JPS61242608A - Preparation of gas permeable membrane - Google Patents

Abstract

PURPOSE:To form membrane having superior strength, heat resistance, and solvent resistance by using a material forming permeable thin film having photosensitive groups on a porous base material and irradiating the film with light energy or electron energy. CONSTITUTION:A material having ethylenic photosensitive groups such as vinyl group, allyl group, etc. is formed to thin film on a porous base material. If 0.1-30wt% photosensitizer is added to the membrane material, the irradiation time with ultraviolet rays, etc. may be shortened remarkably. Crosslinking polymn. of the photosensitive group proceeds by the irradiation with ultraviolet rays or electron beam, and the structure of the polymer changes from linear structure to net work structure. In accompany with the change of the structure, the polymer becomes insoluble in solvent, and the strength and heat resistance of the film is improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a gas permeable membrane for separating and concentrating gases.
- relates to manufacturing methods;

Conventional technology In recent years, there has been remarkable progress in separation technologies that utilize polymers, such as ultra-E membranes, reverse osmosis membranes, and gas permeation membranes, and some of them have been put into practical use on an industrial scale. . However, one thing that has actually been put into practical use is seawater desalination.
Liquid-liquid separation for processing factory waste liquids, concentrating food (liquid substances), etc.
The separation and concentration of specific gases from a mixture of more than one species has not yet reached the stage of complete practical use, and is currently still at the research stage.

The main reason why conventional gas permeable membranes cannot be put into practical use is that the selective permeability of the membrane material is low, that is, membranes that selectively allow certain gases to pass through while hardly allowing other gases to pass through. Therefore, in order to obtain high-purity gas, it is necessary to adopt a multi-stage method in which membrane separation is repeated several times, which makes the equipment too harsh and the permeation flow rate is small, resulting in the production of a large amount of waste. There are things you can't do.

3'- However, there are many fields that do not necessarily require high-purity gases as end-uses. If the concentration is increased to some extent, so-called oxygen-enriched air, this purpose can be achieved.

Research and development has been actively conducted on so-called oxygen-enriching membranes that concentrate and separate oxygen. Various polymer materials have been synthesized. The present inventors also developed an H8 copolymer containing silicone as a main component (Unexamined Japanese Patent Publication No. 66
-112457) was synthesized. these
□Membrane materials are mainly formed by overlapping separately formed thin films on a porous support, by simultaneously forming an anisotropic film in which a skin layer and a porous support coexist, Direct polymerization of monomers to -F of the porous membrane by various methods,
There is a method of forming a thin film, or a method of forming a thin film by coating a polymer solution and then evaporating the solvent.

Among the above film forming methods, the water surface spreading method [Langmuir-Prodgett film forming method (abbreviated as LB method)] is a typical example of a method in which a thin film is formed by coating a polymer solution and then evaporating the solvent. There is. This method involves dropping a polymer solution onto the water surface, spreading the solution on the water surface, allowing the solvent used to evaporate spontaneously, leaving only the polymer on the water surface, and forming a porous thin film of the polymer. Film formation is completed by adhering it to the support 42. At this time, the polymer on the thin film formed on the porous support is naturally the same in terms of physical properties as the polymer in the solution before spreading on the water surface, and has the same strength and heat resistance. , solvent resistance, etc. are the same, and it is obvious that they are soluble in the solvent used.

The above is not limited to the water surface deployment method;
This also applies to other film forming methods.

Problems to be Solved by the Invention As mentioned earlier, in the conventional film forming method, the properties of the film material itself do not change at all between before and after film formation.
The membrane strength is weak, and the heat resistance and solvent resistance are poor.
It has the drawbacks of being troublesome to handle, being sensitive to changes in the environment, and exhibiting severe membrane deterioration in life tests.

Means for improving the chemical properties, solvent resistance, heat resistance and mechanical strength of porous supports have already been proposed. (
(Refer to JP-A No. 59-136107), this is basically a method in which a porous membrane is formed by forming a resin having a photosensitive group, and then crosslinked by light irradiation. Although they are similar in principle, they are largely different in that they are limited to methods for producing porous supports, and the present invention relates to permeable membrane materials.

However, Mitsubishi Chemical Industries, Ltd. has proposed a method that aims to improve the mechanical strength and gas separation performance of gas separation membranes by crosslinking them. (Unexamined Japanese Patent Publication No. 5
However, in this paper, the crosslinking method is strictly a heat reaction type six-vane method, and even if a crosslinking agent is used, it is quite difficult to accelerate the reaction rate. It needs to be at a high temperature.

In this respect, the present invention uses a photopolymerizable rather than a heat-reactive polymer, and basically oligomers and polymers with photosensitive groups are activated by ultraviolet rays or electron beams, allowing them to interact with each other or other polymers. It is an addition polymerization type that reacts with polymers, oligomers, etc., and is fundamentally different. As described above, the present invention focuses on the strength and heat resistance of the film.

The object of the present invention is to provide a method for producing a body-permeable membrane that is easy to handle and has excellent durability by improving solvent resistance.

Means for Solving the Problems In order to achieve this objective, the method for producing a gas permeable membrane of the present invention involves forming a thin film of a permeable membrane material having a photosensitive group on a porous support, and applying light energy to the membrane. Examples of the porous support for the device, which is polymerized by irradiation with electron energy, include polypropylene.

Polyester, polysulfone, polyethylene, polyethersulfone, and polycarbonate may be used, and the resins that can be used in the present invention are not limited.

Next, as photosensitive groups, vinyl group, allyl group, cinnamoyl group, α-cyanocinnamoyl group, cinnamylideneacetyl group, α-cyanocinnamylideneacetyl group, benzalacetophenone (calco/group), phenylacyl)'
Examples thereof include group+α-phenylmaleimide group, furyl acroyl group, etc. Among them, ethylene-based groups such as vinyl group and allyl group are particularly suitable. Polystyrene,
Typical examples include polyvinyl alcohol, phenoxy resin (condensation resin of epoxy resin and bisphenol compound), polyether with hydroxyl group, polyester with hydroxyl group, polyamide with hydroxyl group, polyallyl alcohol, styrene-maleic acid, and phorisimethyl/roxane. Silicone polymers and the like may be mentioned, or they may be used as a copolymer by using one or more of them as a mixture. Among these, combinations of silicone polymers and other membrane materials are particularly effective in bringing out the characteristics of both permeability and selectivity.

Next, when using ultraviolet rays as the irradiation light source, the irradiation time can be significantly shortened by using a sensitizer as described below.

Peroxides such as benzoyl peroxide, azo compounds such as azobisisobutyronitrile, carbonyl compounds such as diacetyl and dibenzyl, sulfur compounds such as digenyl mono and disulfide, dibenzoyl mono and disulfide, halogen compounds such as carbon tetrachloride, Metal salts such as ferric salts,
Ether compounds such as benzoin isopropyl ether, etc. The sensitizer for cholera is usually 0.1 to 30% relative to the membrane material.
For weight divisions, hereditary use of 0.6 to 6 weight divisions is effective. When used, it is important to select a sensitizer that is most compatible with the solvent of the membrane material.

In addition, there is no particular limitation on the irradiation light source, and the purpose can be achieved by using one that is used in general chemical reactions of -9Hage, but especially in the case of ultraviolet irradiation -1
, the intensity varies depending on the light source, so the degree of polymerization of the film is
The degree to which the irradiated film becomes insoluble in tetrahydrofuran is used as a guideline.

Function: With the above structure, a thin film of a film material having a photosensitive group can be formed on a porous support in the conventional manner without twisting.

In this state, since the membrane material is simply a chain polymer or oligomer, it is easily dissolved in a solvent such as tetrahydrofuran or dimethylformamide. Next, when the obtained thin film is irradiated with ultraviolet rays or electron beams, polymerization (crosslinking) progresses due to the photosensitive groups in the film material, and the basic chain structure changes to a network structure. go. Along with this, it becomes poorly soluble in solvents such as tetrahydrofuran and dimethylformamide, which were previously soluble, and eventually becomes completely insoluble. In addition, along with such improvement in solvent resistance, film strength and heat resistance also improve, reaching <1/1>. In the case of ultraviolet irradiation, a sensitizer is often used as mentioned above, but even in this case, the sensitizer is cleaved by the ultraviolet rays, and the reaction of the membrane material begins accordingly. Eventually, it will take on a sufficient network structure. However, depending on the type of membrane material, the proportion of photosensitive groups included, and the type and amount of sensitizer added, some membranes may become insolubilized but swell significantly and exhibit a gel-like appearance. however,
Most membranes are sufficiently insolubilized by solvents such as methanol and acetone, and exhibit little swelling.

EXAMPLES Next, the present invention will be explained in more detail based on Examples, but the content of the present invention is not limited only to the Examples.

(Example 1) Polydimeteryl, loxane, vinyl-based material at both ends.

Gum-like 5H-410 (manufactured by Toshi Silicone Co., Ltd.) is dissolved in benzene to form a solution of approximately 20 times the strength. to this,
Add 1% by weight of benzoin propyl ether (hereinafter referred to as BIPE) based on the weight of 5H-410, and stir thoroughly to make it homogeneous. This is spread on the water surface, and after the solvent has sufficiently evaporated, it is deposited on Duragard 240o (porous support made of polypropylene, manufactured by Polyplastics@). In order to prevent the pinhole nature of this film removal, this operation is repeated again, resulting in the formation of two layers of 5H-410 thin film on Duraguard. Next, add the light source (– to the mercury lamp [■
Toshiba mercury wrap for physical and chemical use 5HLS-1002A type (
Lamp 5I (L-1oooA, 1ooV, 50C/S
, 2A):], and irradiation was performed for about 20 seconds at an irradiation intensity of 6.6 mW/cnf. Next, we investigated the characteristics using a bubble flow meter (a device that allows equal volumes of oxygen and nitrogen to pass through the membrane under -atmosphere pressure, and evaluates the characteristics based on the number of seconds). At 15.2 seconds per 10 CC, the separation factor was 2.1. On the other hand, for the non-irradiated sample, the oxygen permeation time was approximately 9.0 seconds per 10CG, and the separation coefficient was 1.4, but it gradually became unable to reach the pressure of 1 atm and became a pinpole, making it impossible to measure. became.

(Example 2) 5H-41o, which is the same material O.1 as in Example 1, was
A 20% weight benzene solution was prepared, and this was spread on the water surface to form a two-layer film on Duragard 24oO.

Next, the obtained film was subjected to electron beam irradiation using an area beam type electron beam irradiation device (manufactured by Guatron 2 Nisshin High Voltage Steel 0 for research use). After irradiation for 0.1 seconds at an irradiation intensity of 2 megarads, its characteristics were examined using a bubble flow meter.The oxygen permeation time was 1occ-2/14 seconds, and the separation factor was 2.2. .

In contrast, the unirradiated film had an initial oxygen permeation time of 10C.
The separation coefficient was about 1.3 at 8.6 seconds per G, but
In the end, it became a pinhole and could not be measured.

Next, the irradiated and unirradiated membranes were treated with benzene,
When immersed in tetrahydrofuran and dimethylformamide solvents, taken out after 24 hours, and measured using a bubble flow meter, the unirradiated film had a complete pinhole concentration of 13 bases in all solvents.

Although it was not possible to measure the properties using the irradiation method, the membrane maintained its properties in all solvents, and the oxygen permeation time (in the case of IOCC) was 14, 2, and 14.3°, respectively. 14
．． 1 second, and its separation coefficient is 2.1.2, 2.1
.

It was 2.2.

Next, three layers of 5H-410 were formed on Duraguard 2400 using the method described above, and the characteristics of those subjected to electron beam irradiation (~) and those that were not irradiated were investigated. 17.5 seconds, 'At 17.0 seconds the separation factor is 2
．． It was 2 and 2゜1.

The irradiated film and the non-irradiated film were placed in a moisture-proof tank at 951RH at 951 RH as one of the indicators of accelerated deterioration test, and the relationship between the entrance pupil and the characteristics was investigated. Results first
As shown in the figure.

As shown in Figure 1, the unirradiated one shows extremely severe deterioration, but
The irradiated material is stable, and considering the film properties, it is thought that there is essentially no deterioration in moisture resistance.

(Example 3) A part of the phenolic OH'4 of polyhydrogystyrene (hereinafter abbreviated as lPH8) was replaced with an aliyl group 14
Replaced with page. Dissolve this in monochlorobenzene, then add a,ω-diaminopolydimethylsiloxane, stop the addition when the viscosity of the solution is 10 cp, precipitate the reactant in methanol, and repeat the purification three times. ,
Vacuum drying was performed.

Next, this was made about twice hereditary with benzene, and a film was formed by the water surface spreading method. The film was formed into a two-layer structure on Duraguard. When the properties of the obtained membrane were measured using a bubble flowmeter, the separation coefficient was 2.1° and the number of seconds for oxygen permeation per 10 CG was 9.6 seconds. Next, a film similar to this was subjected to electron beam irradiation using the apparatus used in Example 2. After irradiation,
When the membrane properties were investigated, the separation coefficient was 2. Thank you 10(,C
The number of seconds per oxygen permeation was 10.3 seconds. Next, the coating material itself was dissolved in tetrahydrofuran, and a film was formed on a glass substrate by a casting method. The thickness of the obtained film was approximately 100 μm, and the film was irradiated with electron beams using a device that had previously measured the thickness of the film. The irradiated membrane was then immersed in tetrahydrofuran, but it no longer dissolved. In this case, due to the difference in the allylation rate, the d-decomposition d of the irradiated film for tet-15...-7 lahytronolane or dinotylformamide may be different, or an allylation rate of about 70 is experimentally better. Ta.

(Example 4) 20 g of the allylated product of PH8 (allylation rate 70%) synthesized in Example 3 and a silicon oligomer having a methacryloxypropyl group [X-22-5002, manufactured by Shin-Etsu Chemical Co., Ltd. )] was mixed with 10 g. Next, 10g of toluene was added and thoroughly stirred to make it homogeneous. This was spread on the water surface, and a film was formed twice on Duraguard, followed by electron beam irradiation. The unirradiated one had almost no film-forming ability and could not withstand the pressure of 1 atm from the bubble flowmeter, and was completely pinhole, but the irradiated one had a separation coefficient of 2.3. The number of seconds for oxygen permeation per 10 CG was 10.1 seconds. Further, when an accelerated test was conducted in a humidity-resistant tank at 60° C. and 95 RH, the irradiated film remained almost unchanged even after 1000 hours, and the same results as in FIG. 1 were obtained.

(Example 5) Monomethyl heptanovinyl dichlororane was used as the starting material,
Water was added to this and then aminated with diethylamine to synthesize the siloxane shown below.

CH=CHCH=CH CH3CH3 n=30.62.70 Next, allylated PH8 (allylation rate 70%) sg used in Example 3 was dissolved in 3 ooml of monochlorobenzene, and after heating at SO'61, 10 g of the previously synthesized siloxane (degree of polymerization n = 30) was added to carry out synthesis. After the reaction was completed, the reaction solution was precipitated in a large amount of metallol, purified, and vacuum dried at 40'C for 24 hours. Next, the obtained composite was dissolved in tetrahydrofuran and cast on a glass substrate to form a thin film of about 100 μm. Next, a part of this thin film was irradiated with an electron beam and then immersed in tetrahydrofuran.The unirradiated part completely dissolved, but the irradiated part remained almost undissolved, and even after being left for 24 hours. No changes were observed.

(Example 6) Next, 85 g of PH was dissolved in 250 ml of 1,4-dioxane, and diethylaminosiloxane iog having a vinyl group in the side chain used in Example 5 was added to perform synthesis. Similar to Example 5, precipitate in methanol,
After purification, vacuum drying was performed at 4°C for 24 hours. Next, the composite was made into a double-stripe solution with benzene, and a film was formed by a water surface development method. Next, electron beam irradiation was performed, and its characteristics were determined using a bubble flow meter. The unirradiated one has a separation factor of 2.
．． 1. The number of oxygen permeation seconds per 10CG is 10.6 seconds,
The irradiated one had a separation factor of 2.2. Oxygen permeation seconds is 11
．． It was 0 seconds. These films were heated at 60°C as in Example 2.
When we conducted an accelerated deterioration test in a 95% RH humidity tank, as shown in Figure 2, the properties of the unirradiated film deteriorated after about 500 hours, but the properties of the irradiated film deteriorated after 1000 hours. It can be seen that 18 l·-/ hardly changes even after the passage of time.

In a benzene solution of 2 parts by weight, add α, σ'-azobisisobutyronitrile [Kanto Kagaku ■] as a sensitizer.
0.1 part by weight of the entire solution was added, a film was formed on the water surface, irradiated for 20 seconds with the UV lamp used in Example 1, and tested in a moisture-resistant tank at 60°C and 95% RH. As a result, characteristics similar to those shown in FIG. 2 described above were obtained.

(Example 7) 3 g of allylated PH8 (allylation rate 70%), 6 y of polysulfone (Mn ~ 5000), 6 oom of chlorobenzene
18 g of diethylaminoborodimethylsiloxane was added at 80° C. to carry out synthesis. The reaction solution was poured into methanol from 1 to 1, and then purified, 24
Vacuum drying was performed at 40°C. Next, this was made into a solution of 2 parts by weight in toluene, and a film was formed by the water surface spreading method, followed by electron beam irradiation in the same manner as in the previous example, and changes in the characteristics of the unirradiated film and the irradiated film were observed. The test was conducted in a heat-resistant tank at 60° C. and 95% RH. The results are similar to Figure 2, with 19 bases.
2 It is clear that the irradiated film has considerably better durability than the non-irradiated film.

As described above, according to this example, by forming a thin film of a transparent film material having a photosensitive group and polymerizing it by irradiation with light or electronic energy, the strength of the film property, heat resistance, and solvent resistance are improved. It is possible to obtain a film that is easier to handle and more durable than conventional ones.

Effects of the Invention As described above, the present invention improves the strength of the film by forming a thin film of a transparent film material having a photosensitive group and polymerizing (crosslinking) it by irradiation with light energy or electron energy.
It has excellent heat resistance and solvent resistance, and is easier to handle than conventional films and can provide a film with excellent durability, and its industrial effects are outstanding.

[Brief explanation of drawings]

Figure 1 is a characteristic comparison diagram of the irradiated film and unirradiated film in Example 2 of the present invention in a 60°C 95% RH humidity tank, and Figure 2 is a comparison diagram of the irradiated film and unirradiated film in Example 6 of the present invention ℃95%
It is a characteristic comparison diagram in an RH moisture-resistant tank.

Claims (4)

[Claims] (1) A method for producing a gas permeable membrane, which comprises forming a thin film of a permeable membrane material having a photosensitive group on a porous support, and polymerizing (crosslinking) it by irradiation with light energy or electronic energy. (2) The method for producing a gas permeable membrane according to claim 1, wherein the thin film of the permeable membrane material having a photosensitive group has a multilayer structure. (3) The method for producing a gas permeable membrane according to claim 1, wherein the light energy is ultraviolet rays. (4) The method for producing a gas permeable membrane according to claim 1, wherein the electron energy is an electron beam.