JPS6071006A - Gas permselective membrane - 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 relates to a selective gas permeable membrane that has good gas separation properties and excellent gas permeability.

Structure of conventional examples and their problems Separation technology using membranes has made remarkable progress in recent years, and has already been put into practical use on an industrial scale in several fields, such as seawater desalination and recovery of useful substances from factory waste liquid. .

On the other hand, in the separation of mixed gases using organic polymer membranes, the selectivity of the membrane is low, and it is difficult to selectively obtain high-purity gas with general separation, and the permeation flow rate is small, so a large amount of gas is produced. There are few practical examples of gas separation using membranes for reasons such as the inability to do so.

However, there are many fields where high purity gas is not necessarily required for the end use of gas. For example, in the case of oxygen, high purity oxygen is not required for blast furnace ventilation, fuel supplementation, medical breathing, etc.

On the contrary, if the purity is high, the combustion temperature will rise too high, which can cause damage to the furnace, a risk of fire, and blindness in premature babies. Therefore, gas separation methods using membranes are advantageous in such fields.

In the separation of oxygen from air by membranes, it is difficult to obtain air with high purity of oxygen in one stage of separation, but air with moderate oxygen enrichment can be obtained relatively easily. In other words, the membrane separation method can directly produce oxygen-enriched air with an oxygen concentration of about 26 to 50% from air, and there is no need to handle mixers or cylinders, making it easy to operate and economically advantageous. It is.

As has already been pointed out in several documents and patents regarding the separation of mixed gases using polymer membranes,
The important issues are the permeability coefficient of the polymer membrane to gas, the mechanical strength of the membrane as a thin membrane, and the thinning technology.

Among the currently reported polymer materials, substances with relatively excellent gas permeability include natural rubber, synthetic rubber such as polybutadiene, polyolefin, and silicone rubber, which is even more excellent.

This silicone rubber is better against almost all gases than any other polymeric material. Silico-yi, that is, polyorganosiloxane, exhibits the property of low molecular interaction and high siloxane bondability, which is interpreted as the reason for its excellent gas permeability. has been done. However, on the other hand, the above properties are closely related to a decrease in mechanical strength, and the small interaction between polymer chains makes the polymer as a whole amorphous and further advances mechanical strength. It also causes a significant decrease in strength. Therefore, in the case of silicone, the only way to use it for separation membranes is to crosslink it by vulcanization to form silicone rubber. As is well known, silicone rubber as a general structural material has excellent weather resistance and sufficient mechanical strength, but in order to use it as a gas permeable membrane, the above-mentioned vulcanization process is required. This was a major drawback in thin film production.

In order to overcome the above-mentioned drawbacks and facilitate the film forming method, block copolymers of silicone and other polymers, such as polydimethylsiloxane-polycarbonate, have been proposed. Because other polymer units are introduced into the polydimethylsiloxane unit, such copolymers have mechanical strength that allows them to be made into thin films without vulcanization compared to silicone rubber, and they also have organic Since it is a solvent-soluble polymer, casting and other general methods can be used to form a film, making it extremely easy to form a thin film.

However, on the other hand, the gas permeability is reduced and is about one-third that of silicone. Also, the gas separation property does not improve, and the gas permeability coefficient ratio of oxygen and nitrogen is 2.1, which is almost the same as silicone.
It is. These are because the gas permeability of the copolymer is controlled by the silicone component, so it is possible to improve the gas permeability of the silicone itself and to copolymerize it to create a material with mechanical strength that is insufficient for practical use. If obtained, it would be possible to obtain a gas permeable membrane with better gas separation properties than the above block copolymers.

Purpose of the Invention The present invention has been made in view of the above points.
The object of the present invention is to provide a selective gas permeable membrane that has excellent gas permeability and sufficient mechanical strength.

Structure of the Invention The present invention relates to a polyfunctional styrenic polymer having an aromatic ring in its side chain, an aromatic polysulfone, and a polyether.

A copolymer obtained by reacting a mixture with a terminally functional polymer such as polyester or polyamide with an α,ω-2 functional polyalkylmethylsiloxane and then further reacting an α,ω-2 functional polydimethylsiloxane. This is a selective gas permeable membrane whose main component is a polymer.

Description of examples The present invention will be described in detail below based on embodiments.

The method used to produce the copolymer according to the present invention is α, ω-2
Styrenic polymers, polysulfones, polyethers, polyesters, and polyamides that have functional groups that can react with functional polysiloxanes can be easily used, and since the reaction is a simple polymer reaction, the range of application is wide and the manufacturing conditions are flexible. This is an excellent method that is simple and inexpensive to manufacture. The membrane material thus obtained will be explained in more detail below.

The polyfunctional styrenic polymer used in the present invention has the general formula (where Y is a substituent selected from the group consisting of hydrogen atom, methyl group, ethyl group, propyl group, and butyl group, and X is Alkyl group,) A halogenated alkyl group.

Substituents represented by trimethylsilyl group, toluethylsilyl group and derivatives thereof, m is an integer of 1 to 3, B/A=
o, 1 to 2.047) range) It is a styrenic polymer having an aromatic ring in the side chain represented by Te, and the terminal functional polymer has the general formula % (however, R1 is a divalent 7-enol residue). , R2 is any one of polysulfone, polyether, polyester, and polyamide represented by a group selected from the group consisting of ester residue, ether residue, aromatic sulfone residue, and amide residue. It is. These styrenic polymers, polysulfone, polyether, polyester,
In the mixture with any one type of polyamide, a substituent selected from the general formula (where R is an alkyl group and) and a rogenated alkyl group, Z is a norogen atom, an alkoxyl group, a hydroxyl group, an amino group, a dimethylamino group, It is a functional group selected from the group consisting of diethylamine group and epoxy group. ), n is 4 or more and 100
The value is preferably 4 or more and 80 or less.

However, since the terminal reactivity of α,ω-2 functional polyalkylmethylsiloxane decreases, the copolymer cannot be made into a polymer by this reaction alone, and its mechanical strength becomes weak.

Therefore, we further reacted with α,ω-2 functional polydimethylsiloxane, which has excellent terminal reactivity, to polymerize it. At this time, the α, ω-2 functional polydimethylsiloxane has the general formula (where Y is a halogen atom, an alkoxyl group, a hydroxyl group,
selected from the group consisting of an amino group, a dimethylamino group, a diethylamino group, and an epoxy group. ), and when this is reacted, m is preferably 4 or more and 200 or less, preferably 8 or more and 100 or more, and has sufficient mechanical strength, which is considered to be based on the copolymerization of polysulfone, polyether, or polyester. In particular, it has film strength when formed into a thin film, is soluble in organic solvents, and can therefore be easily formed into a thin film by casting or other methods. By the way, 1.0 μm can be easily obtained using the Langmuir method using a benzene solution of the copolymer.
The following thin film could be obtained. Max 1o ”cc,
tyn/d, 5ec-tynkUl, and a very high value of 2.80 in the ratio of oxygen and nitrogen permeability coefficients.

Next, specific examples will be described in which cases in which α, ω-2 functional polydimethylsiloxane is not reacted and cases in which it is reacted.

Example 1 Polyhydroxystyrene (trade name, Ruse, Residim-=5,7oo) was used as a polyfunctional polymer, and aromatic polysulfone (MwL; 5.ooo) 3 was used as a terminally reactive polymer, and the composition was changed to the former. is 2t1. The latter added 4 g to 15 Qml of chlorbenzea and 100 ml of 1,4-dioxane.
Dissolve the solution in a mixed solvent of
Set up in a 3-tube flask equipped with a N2 injection tube, 2 dropping funnels, and a thermometer. The reaction system was heated to about 90°C, stirred with a stirrer, and α,ω-bis(dimethylamino)
Polyhexylmethylsiloxane (n=1e) at 159
Gradually drip the solution over a period of about 1 hour from the dropping funnel. As the reaction progresses, polymerization should occur and the viscosity of the solution should increase, but in the case of this composition, no increase in viscosity was observed even after about 3 hours.

Therefore, the reactant was precipitated in a large amount of methanol in this state and purified by a reprecipitation method to obtain a copolymer. By analyzing the infrared absorption spectrum and molecular weight distribution characteristics of this copolymer by Kel permeation chromatography (GPC), α.

It was confirmed that ω-bis(dimethylamino)polyhexylmethylsiloxane (n4; 16) did not react stoichiometrically. As a result, the molecular weight of the copolymer becomes lower,
Mechanical strength has also become weaker. Furthermore, even when α,ω-bis(dimethylamino)polyhexylmethylsiloxane was further applied to this copolymer, no reaction occurred, making it difficult to polymerize the copolymer.

Example 2 In order to polymerize the copolymer and give it mechanical strength, 2 g of α,ω-bis(diethylamino)polydimethylsiloxane (n≠18) was added to the copolymer of Example 1. Example 1
The reaction was carried out under the same reaction conditions. As a result, the viscosity of the copolymer solution increased and polymerization was confirmed. The reaction solution was poured into methanol to obtain a reaction precipitate, which was then purified by a reprecipitation method. GPC measurements of this copolymer showed that its molecular weight ranged from 15-20Q to 10,000. Next, in order to find out the gas permeability of the copolymer, the copolymer was dissolved in tetrahydrofuran and formed into a film by a casting method, and the gas permeability properties were measured. As a result, the gas permeability coefficient is 1 for oxygen, 6X 1
0'CCcm/J, SIN, (yHH9, 5.2X10''CCcmlcyl-5ti-cm with nitrogen
The separation ratio α for H5′ was 2.88.

Example 3 A 5% by weight benzene solution of the copolymer of Example 2 was prepared and formed into a thin film using the Langmeer method.

A polypropylene porous support (manufactured by Polyplastics, trade name: DURAGUARD) was used as a support for the thin film.

First, after spreading the copolymer membrane on the water surface, the developed membrane was adhered to a support to form a composite membrane, and the gas permeation flow rate was measured and the effective membrane pressure was converted. 20
It was found that the film has film formability and mechanical strength that can be easily adjusted to ultra-thin film thickness of 0.00.

Effects of the Invention As described above, the present invention provides a mixture of a polyfunctional polymer and a terminally functional polymer with α, ω-2 functional polyalkylmethylsiloxane and α, ω-2 functional polydimethylsiloxane. This is a selective gas permeable membrane whose main component is a copolymer obtained by the above process, and has sufficient mechanical strength, high gas separation properties, and excellent gas permeability.

This selective gas permeable membrane can be used for mixed gases other than oxygen and nitrogen, and can be used in internal combustion engines, steel industry, food industry, medical equipment, waste treatment, etc.

Claims (3)

[Claims] (1) Mixture of polyfunctional polymer and terminal functional polymer and α
, ω-2 functional polyalkylmethylsiloxane and α
The main component is a crosslinked copolymer obtained from ω-2 functional polydimethylsiloxane, and the polyfunctional polymer has the general formula (where Y is a hydrogen atom, methyl group, ethyl group, propyl group, or butyl group). a substituent selected from the group consisting of a substituent selected from the group consisting of; /
It is a styrenic polymer having an aromatic ring in the side chain represented by A-o (range of 1 to 2.0), and the terminal functional polymer is A selective gas permeable membrane characterized in that it is a material represented by a phenol residue (R2 is a group selected from the group consisting of an ester residue, an ether residue, an aromatic sulfone residue, and an amide residue). . (2) α, ω-2 functional polyalkymethylsiloxane has the general formula (where R is a substituent selected from the group consisting of an alkyl group and a halogenated alkyl group, and 2 is a halogen atom, an alkoxyl group, a hydroxyl group, an amine The selective gas permeable membrane according to claim 1, which is a material represented by a functional group selected from the group consisting of a dimethylamino group, a diethylamine group, and an epoxy group. (3) α, ω-2 functional polydimethylsiloxane has the general formula (where Y is a halogen atom, an alkoxyl group, a hydroxyl group,
A functional group selected from the group consisting of an amine group, a dimethylamino group, a diethylamino group, and an epoxy group. ) The selective gas permeable membrane according to claim 1, which is a material represented by: