JPH0331092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a gas permeable membrane that has excellent oxygen/nitrogen separation properties and a large permeability coefficient.

Configuration of conventional examples and their problems In recent years, material separation technology using polymer membranes has made remarkable progress, and not only liquid treatment but also the development of concentrated separation of specific gases from various gas mixtures has been actively conducted. There is.

Among these, the production of oxygen-enriched air by concentrating oxygen from the air is useful for a wide range of applications, including combustion, medical use, and sludge treatment, and various polymer separation membranes have therefore been proposed.

Conventionally, silicone membranes, polyolefin membranes, polyphelene oxide membranes, and the like are known as such polymer separation membranes, ie, oxygen permeable membranes, for producing oxygen-enriched air. Although these membranes each have practical performance, they are still unsatisfactory in their separation selectivity and permeability.

For example, silicone membranes have a relatively high oxygen permeability coefficient of ~10 ^-8 (cc・cm/cm ²・sec・cmHg), but have a low oxygen/nitrogen selectivity of ~2; For phenylene oxide-based polymers, the selectivity is as high as ~4, but the oxygen permeability coefficient is ~10 ^-9 ~10 ^-10 (cc・cm/cm ²・
sec・cmHg).

OBJECT OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional technology.
The object of the present invention is to provide a gas permeable membrane having excellent gas permeability and gas selectivity.

Structure of the Invention As a result of extensive research into gas permeable membranes that have large values for both selectivity and permeability coefficient, the present inventors have found that a polymer membrane having the structure shown below has large selectivity and permeability. This discovery led to the present invention.

That is, the general formula is a gas permeable membrane made of a linear polymer having repeating units as shown below. Here, R ₁ to _{R 4} each represent a substituent selected from the group consisting of hydrogen, a lower alkyl group, an alkoxyl group, a halogen atom, and a halogenated alkyl group, and R ₅ and R ₆ each represent hydrogen, It represents a substituent selected from the group consisting of a lower alkyl group, a phenyl group, and a trifurkylsilyl group, and x represents the content ratio of aromatic ring to unsaturated double bond, and 0.1<
x<0.9.

Such polymer materials have recently attracted attention as materials with excellent conductivity. The intermediate of this phenylene-vinylene polymer is soluble in solvents and can be easily cast into a film.

The present inventors focused on and measured the gas permeability of the films obtained by the above-mentioned casting, and discovered that these films exhibited extremely excellent gas permeability.

These polymers can generally be synthesized using Wittig reaction or Knoevenagel reaction.

The resulting polymer intermediate is soluble in aqueous solution;
It was easy to cast and make film. This can be thermally decomposed into a predetermined film.

Characteristics vary depending on the individual material, but as a result of examining oxygen permeability, it is 10 ^-9 to 10 ^-8 (cc・cm/cm ²・
sec·cmHg) value, and its oxygen/nitrogen selectivity was extremely large, ranging from 2 to 3.5.

Hereinafter, a detailed explanation will be given using typical examples.

Description of Examples <Example 1> P-xylylene bis(diethylsulfonium bromide) aqueous solution was added at a temperature of 0 to 5°C.
Add the caustic soda aqueous solution dropwise and stir for about 6 hours.
Polymerized for hours. After the reaction is completed, the product is dialyzed,
Low molecular weight substances were separated. The purified aqueous solution was cast and dried under reduced pressure to obtain a film. The obtained film was heat-treated at 250 to 300°C for 21 hours in a nitrogen stream. The gas permeability of this film was examined by a predetermined method.

o ₂ = 4.5×10 ^-9 (cc・cm/cm ²・sec・cmHg) Po ₂ /PN ₂ = 3.45.

<Example 2> Except that bis(a,α'-diethylsulfonium bromide) 1,4-diethylbenzene was used as the raw material,
A film was formed in the same manner as in Example 1. The obtained film had a permeability of o ₂ =1.5×10 ⁻⁸ (cc·cm/cm ² ·sec·cmHg) Po ₂ /PN ₂ =3.0.

<Example 3> A film was formed in the same manner as in Example 1 using 2,5-dimethoxy-1,4-xylylene bis(diethylsulfonium bromide) as a raw material. The obtained film had a permeability of o ₂ =2.2×10 ⁻⁸ (cc·cm/cm ² ·sec·cmHg) Po ₂ /PN ₂ =2.75.

Effects of the Invention In summary, the present invention provides a gas permeable membrane made of a linear polymer having a general formula having repeating units as shown below. Here, R ₁ to _{R 4} each represent a substituent selected from the group consisting of hydrogen, a lower alkyl group, an alkoxyl group, a halogen atom, and a halogenated alkyl group, and R ₅ and R ₆ each represent hydrogen, It represents a substituent selected from the group consisting of a lower alkyl group, a phenyl group, and a trialkylsilyl group, and x represents the content ratio of an aromatic ring to an unsaturated double bond, and 0.1<
x<0.9.

Such a gas permeable membrane has extremely high gas permeability and high selectivity, and when used for oxygen separation to produce oxygen-enriched air, it can be used for a wide range of purposes, including combustion, medical, and sludge treatment. It is something.

Claims (1)

[Scope of Claims] 1. A gas permeable membrane made of a linear polymer having a general formula having repeating units as shown below. Here, R ₁ to _{R 4} each represent a substituent selected from the group consisting of hydrogen, a lower alkyl group, an alkoxyl group, a halogen atom, and a halogenated alkyl group, and R ₅ and R ₆ each represent hydrogen, It represents a substituent selected from the group consisting of a lower alkyl group, phenyl group, and trialkylsilyl group, and x represents the content ratio of aromatic ring to unsaturated double bond, and 0.1<
x<0.9.