JPS63190616A - Gas separating membrane - Google Patents

Abstract

PURPOSE:To enhance selective permeability of O2 by forming a gas separating membrane out of a chain macromolecule prepared by copolymerizing one kind or more of monomers having oxyethylene unit and one other ethylene group unsaturated monomer. CONSTITUTION:One kind or more of monomers having oxyethylene unit shown by a formula of methoxytetraethylene glycol methacrylate or the like (R1 is acryloid, methacryloid, vinyl, aryl or the like. R2 is alkyl with C1-8, cycloalkyl or phenyl with C3-8. n is 1-50.) and an ethylene group unsaturated monomer such as methyl methacrylate, vinyl acetate or the like are copolymerized, and 5-50wt.% of an oxyethylene monomer is contained therein. A membrane is prepared out of a chain copolymer thus prepared, and used as a gas separating membrane to enhance selective permeability of O2 to N2 and CO2.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a gas separation membrane, and more specifically, it relates to a gas separation membrane for oxygen, nitrogen,
This invention relates to a gas separation membrane with excellent permselectivity for carbon dioxide, etc.

<Prior Art> Conventionally, attempts have been made to separate and concentrate specific components from a mixed gas using various polymeric materials.

Their main purpose is to concentrate and separate oxygen and nitrogen from air. For example, JP-A-54-56985 discloses a polyorganosilane film, and JP-A-54-146277 discloses a poly(4-methyl-pentene-1) film. The use for obtaining enriched air is disclosed.

<Problems to be solved by the invention> These conventionally known materials for polymer membranes are the following three:
It was not possible to satisfy all points.

(1) The permeability coefficient of the gas to be separated is high.

(21) The selection coefficient of the gas to be separated is high.

(3) Scales have good workability and can be made into thin films.

For example, when separating and concentrating oxygen from air, the polyorganosilanes mentioned above have a high oxygen permeability coefficient but a low selectivity coefficient, and homopolymers have low mechanical strength, so they cannot coexist with other components. The reality is that polymerization is performed to make the film thinner at the expense of the permeability coefficient. Furthermore, although poly(4-methylpentene-1) has a relatively high selectivity coefficient, its permeability coefficient is low, which poses a practical problem. Moreover, in these polymeric materials.

It has problems such as the permeability coefficient for oxygen and nitrogen being lower than the permeability coefficient for carbon dioxide.

<Means for Solving the Problems> In order to improve these drawbacks of the conventional techniques, the present inventors conducted extensive research and developed a method of copolymerizing a monomer having an oxyethylene unit represented by the following general formula (1). The present invention was completed based on the discovery that the resulting copolymer can be easily formed into a thin film and has excellent gas selective permselectivity.

That is, the present invention relates to the following general formula (1) % formula % (1) (wherein R represents an acryloyl group, a methacryloyl group, a maleoyl group, a fumaroyl group, an itaconoyl group, a vinyl group, a vinylbenzyl group, or an aryl group. Representation, R
2 represents an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or a phenyl group, and n represents an integer of 1 to 50. ) is a substantially chain-like copolymer obtained by copolymerizing one or more monomers having oxyethylene units with other ethylenically unsaturated monomers, , the copolymer has 5 to 50 oxyethylene units.
An object of the present invention is to provide a gas separation membrane characterized in that it is a chain polymer containing parts by weight.

The polymerizable group represented by R in the monomer having an oxyethylene unit represented by the general formula (1) used in the present invention can be polymerized with the other ethylenically unsaturated monomers mentioned above. , an acryloyl group, a methacryloyl group, a maleoyl group, a fumaroyl group, an itaconoyl group, a vinyl group, a vinylbenzyl group or an aryl group.

In the monomer having an oxyethylene unit represented by the general formula (1) used in the present invention, the group represented by R1 is an alkyl group having 1 to 8 carbon atoms.

A cycloalkyl group or phenyl group having 3 to 8 carbon atoms is used. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, isopropyl group, n-butyl group, 1s
o-butyl group, 5ec-butyl group, tart-butyl group, n-amyl group, 1so-amyl group, n-hexyl group, 1so-hexyl group, 2-ethylhexyl group, trimethylhexyl group, n-octyl group, etc. Examples of the cycloalkyl group having 3 to 8 carbon atoms include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, and derivatives thereof.

In the monomer having an oxyethylene unit represented by the general formula (1) used in the present invention, the oxyethylene unit is used within the range where n is an integer of 1 to 50.

These monomers having oxyethylene units represented by the general formula (I) can be synthesized by applying an esterification reaction, vinylation, initiation reaction or termination reaction of living polymerization of ethylene oxide, and the like.

Specific examples of the monomer having an oxyethylene unit represented by the general formula (1) used in the present invention include methoxyethyloxy(meth)acrylate, phenoxyethyloxyethyl(meth)acrylate, and methoxydiethylene glycol(meth)acrylate. Acrylate, Isobutoxytetraethylene glycol (meth)acrylate, Methoxypolyethylene glycol (meth)acrylate, Methoxypolyethylene glycol monomaleate, Methoxypolyethylene glycol momarate, Methoxypolyethylene glycol monofumarate, Methoxypolyethylene glycol difumarate, Methoxypolyethylene glycol mono Itaconate, methoxypolyethylene glycol diitaconate.

Ethoxypolyethylene glycol (meth)acrylate, Impropoxypolyethylene glycol (meth)acrylate, Isobutoxypolyethylene glycol (meth)acrylate, Phenoxypolyethylene glycol (
Examples include meth)acrylate, methoxypolyethylene glycol vinyl ether, phenoxypolyethylene glycol vinyl ether, methoxypolyethylene glycol vinylbenzyl ether, cyclohexyloxypolyethylene glycol vinylbenzyl ether, methoxyethylene glycol aryl ether, and phenoxypolyethylene glycol aryl ether.

The polymer used as the gas separation membrane according to the present invention is as follows.

Homopolymers of the monomers have poor film-forming performance, so they are used by copolymerizing them with other ethylenically unsaturated monomers.

Such ethylenically unsaturated monomers have the general formula (
Any monomer copolymerizable with the monomer having an oxyethylene unit shown in 1) can be used.

Preferred are acrylic esters, methacrylic esters, vinyl ethers, vinyl acetate, or styrene and their derivatives from the viewpoint of ease of commercial handling and film-forming properties.

In the copolymer, if the content of oxyethylene units is high, film forming properties will be reduced, and if the content is low, gas permeability and selectivity will be reduced. Contains 45 parts by weight.

The copolymer used as the gas separation membrane of the present invention is a substantially linear chain polymer, and if the molecular weight is small, the mechanical strength will be reduced and the film forming property will be poor. Therefore, the weight average molecular weight of the copolymer is 10,000 to s'oo, ooo, taking into consideration processability and solubility in solvents.

It is preferably 20,000 to 500,000.

The copolymer of the present invention comprises one or more monomers having an oxyethylene group represented by general formula (1) and one or more other ethylenically unsaturated monomers, It can be easily obtained by polymerization in a solvent or without a solvent in the presence of a suitable radical polymerization initiator. Examples of radical polymerization initiators that can be used in this radical copolymerization include various organic peroxides, azo compounds, persulfates, perhalogenates, and redox reagents.

Further, polymerization initiation methods such as light, oxygen, radiation, and plasma can be exemplified. Furthermore, industrially known polymerization techniques, such as bulk polymerization, suspension polymerization, and solution polymerization.

All emulsion polymerization methods can be applied.

The copolymer of the present invention includes alcohol, ketone, ether,
It can be dissolved in various solvents such as ester and aromatic to form a polymer solution. This solution can be cast onto a smooth surface such as glass or metal, or onto a water surface, and the solvent can be evaporated to form a film. At this time, by controlling the evaporation rate of the solvent, either a homogeneous film or an anisotropic film can be obtained. The thickness of the membrane of the present invention has practical strength,
In order to obtain sufficient gas permeability, it is usually 0.01 to 30
It is 0μ, preferably 0.05 to 200μ. The membrane of the present invention may be in any form such as a flat membrane, a tubular membrane, or a hollow fiber, and if necessary, filter paper, synthetic paper, porous membrane,
It may be combined with a membrane support such as cloth or nonwoven fabric.

<Effects of the Invention> It is represented by the general formula (1) used in the present invention. Copolymers produced from monomers having oxyethylene units are easy to produce and have excellent processability such as film formation. Furthermore, it has excellent selective permeability for gases such as oxygen, nitrogen, and carbon dioxide.

In particular, it has high barrier properties against carbon dioxide, and has a permeability coefficient ratio of 1.0 or more between oxygen and carbon dioxide, which is superior to conventional polymer materials. The membrane obtained from the copolymer of the present invention has the above-mentioned performance, and can be used as a single membrane or a molded body,
Because gases such as oxygen, nitrogen, and carbon dioxide can be effectively separated and used, it is useful for medical treatment, cultivation agriculture, fisheries, c.
This method can be applied to fields where control of the gas concentration is required, such as in chemicals.

<Examples> The present invention will be explained in more detail below using examples. These examples are provided for illustrative purposes and are not intended to limit the invention in any way.

1"L Isobutoxyethyloxyethyl acrylate 5% by weight
, methoxytetraethylene glycol methacrylate 4
A copolymer having a composition ratio of 3% by weight, 50% by weight of methyl methacrylate, and 2% by weight of 2-ethyl-hexyl methacrylate was mixed with benzene as a solvent.

It was synthesized by a conventional solution polymerization method using 2,2'-azobisisobutyronitrile as a polymerization initiator.

This was precipitated with petroleum ether to obtain a white copolymer. The oxyethylene unit in the copolymer was 29 parts by weight, and the weight average molecular weight of type 1 was 220,000. This copolymer was dissolved in methyl cellosolve to make a 15% solution,
This was cast on the water surface to obtain a thin film with a thickness of 150μ. Table 1 shows the permeability coefficients of this thin film for oxygen, nitrogen, and carbon dioxide.

JMJILΔ Methoxytetraethylene glycol methacrylate 48
% by weight, phenoxypolyethylene glycol aryl ether (n=9) 2% by weight, methyl methacrylate 45
A copolymer with a composition ratio of 5% by weight of vinyl acetate was synthesized by the same method as in Example 1.The oxyethylene unit in the copolymer was 32 parts by weight, and the weight average molecular weight of type 9 was 95.0.
It was 00. A 100μ thin film was obtained by the same method as in Example 1. Table 1 shows the permeability coefficients of this thin film for oxygen, nitrogen, and carbon dioxide.

8% by weight of phenoxypolyethylene glycol vinyl benzyl ether (n=9), 20% by weight of methoxypolyethylene glycol methacrylate (n=6), 1% by weight of styrene
A copolymer having a composition ratio of 0% by weight and 62% by weight of methyl methacrylate was synthesized in the same manner as in Example 1. The oxyethylene unit in the copolymer was 20 parts by weight, and the weight average molecular weight was 130.000. A 150μ thin film was obtained by the same method as in Example 1. This thin film contains oxygen, nitrogen,
Table 1 shows the carbon dioxide permeability coefficient.

Example 4 Methoxytetraethylene glycol methacrylate 48
A copolymer having a composition ratio of 2% by weight of methoxypolyethylene glycol methacrylate (n-50), 2% by weight of methoxyethyl methacrylate, and 48% by weight of methyl methacrylate was synthesized in the same manner as in Example 1. The oxyethylene unit in the copolymer was 33 parts by weight, and the weight average molecular weight of type 1 was 320,000. A 200 μm thin film was obtained in the same manner as in Example 1. This thin film contains oxygen, nitrogen,
Table 1 shows the carbon dioxide permeability coefficient.

A copolymer having a composition ratio of 2% by weight of methoxytetraethylene glycol methacrylate and 98% by weight of ethyl methacrylate was synthesized in the same manner as in Example 1. The oxyethylene unit in the copolymer was 1 part by weight, and the weight average molecular weight was 180,000. A 150μ thin film was obtained by the same method as in Example 1. Table 1 shows the permeability coefficients of this thin film for oxygen, nitrogen, and carbon dioxide.

Sakamogai I Methoxytetraethylene glycol methacrylate 90
A copolymer having a composition ratio of 10% by weight and 10% by weight of methyl methacrylate was synthesized in the same manner as in Example 1. The oxyethylene unit in the copolymer was 57 parts by weight, and the weight average molecular weight of type 1 was 250,000. An attempt was made to form a film using the same method as in Example 1, but a uniform film could not be obtained.

From the Examples and Comparative Examples shown in Table 1, it can be seen that the gas separation membrane of the present invention has excellent permeability and selectivity for oxygen, nitrogen, and carbon dioxide.

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T Immediate/71 Procedural Amendment (Misaki) Showa year/month Mouth + jf R□ Agency Omiya,.
62.4.281, Indication of the case Patent Application No. 18299 of 1988 2, Name of the invention Gas separation membrane 3, Person doing supplementary iE/Relationship with 49 cases Patent applicant (434) Japan? 4, Agent: IT 1-20 No. 5, 11-Toranomon, Minato-ku, Tokyo 105, Subject of amendment (1) Claims J section (2) Specification of the specification ``Detailed Description of the Invention J Section 6, Contents of Amendment''
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(rl, patent, !11 desired range l) The following general formula (riT<, -(QC)I, CII,)n-01<,
---(+) (However, R3 represents an acryloyl group, a methacrylic group, a maleoyl group, a fumaroyl group, an itaconoyl group, a vinyl group, a vinylbenzyl group, or a represents an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, λ or a phenyl group, and rl represents an integer of 1 to 50.)
Q'-l having oxyethylene position 111, represented by
One or more of the et isomers 1- and other ethylenically unsaturated 'l'-Jit isomers are combined with IF (the resulting product 1(f
A gas separation membrane characterized in that the copolymer is a chain-like co-11 polymer containing oxyethylene at the 111-position of 5 to 50 polymers (oil-containing).

2) The above copolymer glue (average molecular weight (10,000
~500,000! 1!
gas separation membrane.

J] f111Ftu 110 Enalen fE /f%U
The gas separation membrane according to claim 1 or 2, which is made of acrylic esters, methacrylic esters, vinyl ethers, vinyl acetate, or styrene and its derivatives.''2 , page 4, lines 9-10, and page 5, line 5 in the present specification.

Page 7, line 14 [At the beginning of lines 1 and 15, and page 12, line 5, ``Aryl J'' will be corrected to ``Allyl.''

Claims (1)

[Claims] 1) The following general formula (I) R_1-(OCH_2CH_2)n-OR_2...(
I) (In the formula, R_1 represents an acryloyl group, a methacryloyl group, a maleoyl group, a fumaroyl group, an itaconoyl group, a vinyl group, a vinylbenzyl group, or an aryl group, and R_2 represents an alkyl group having 1 to 8 carbon atoms, a carbon number 3 ~
8 represents a cycloalkyl group or a phenyl group, and n represents an integer of 1 to 50. ) is a substantially chain-like copolymer obtained by copolymerizing one or more monomers having oxyethylene units with other ethylenically unsaturated monomers, , a gas separation membrane characterized in that the copolymer is a chain polymer containing 5 to 50 parts by weight of oxyethylene units. 2) The weight average molecular weight of the copolymer is 10,000 to 5.
00,000. The gas separation membrane according to claim 1. 3) The gas according to claim 1 or 2, wherein the other ethylenically unsaturated monomer is acrylic ester, methacrylic ester, vinyl ether, vinyl acetate, or styrene and its derivatives. Separation membrane.