JPS62204824A - Oxygen selection permeable membrane - Google Patents

Abstract

PURPOSE:To obtain a membrane of high selective oxygen permeability, easily laminated by utilizing a polymer composed of unsaturated dicarboxylic acid diester containing F atom. CONSTITUTION:A high polymer is prepared by single polymerization of unsaturated dicarboxylic acid diester containing fluorine atom as shown in the formula or copolymerization of other monomer able to be copolymerized. Fumarate is preferably used as unsaturated dicarboxylic acid diester. Copolymerization content of copolymer contains 1-50pts.wt. of unsaturated dicarboxylic acid ester per 100pts.wt. Polymerization is carried out in the presence of radical polymerization initiator under 30-100 deg.C. By utilizing said high polymer, a membrane having oxygen permeability of 8X10<-9>-1.5X10<-7>cm<3>(STP)cm/cm<2> sec.cmHg and oxygen selectivity of 3.2-4.5 is prepared.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to an oxygen selectively permeable membrane, and more particularly to an oxygen selectively permeable membrane obtained by homopolymerization or copolymerization of an unsaturated diester dicarboxylic acid containing a fluorine atom. .

<Prior Art> It has been known for a long time that specific components can be separated from a gas mixture using a membrane made of a polymeric material, and in recent years it has been attracting attention particularly from the viewpoint of resource saving and energy saving. In particular, it would be of great value if oxygen-enriched air with increased oxygen concentration could be obtained continuously at low cost and in large quantities from air by membrane separation.

Currently, oxygen used for medical purposes, such as in nursery boxes for premature infants or in the treatment of patients with respiratory diseases, is diluted from pure oxygen filled in cylinders, but there are important issues such as operability and continuity. However, if a membrane capable of efficiently separating oxygen from air can be obtained, the above drawbacks will be overcome.

Also, various combustion systems, such as internal combustion engines such as automobiles,
If oxygen-enriched air is supplied to boilers, furnaces, steel melting furnaces, home heating appliances, etc., the combustion efficiency will increase and energy savings will be achieved. Furthermore, the supply of oxygen-enriched air is also useful in the tableware industry, food cultivation, fish farming, and other fields.

All currently known polymer materials have gas permeability, but there are large differences in permeability, and the oxygen permeation rate is insufficient for use in industrial gas separation membranes, especially oxygen enrichment membranes. It must be large and the selectivity of oxygen to nitrogen must be high. The gas permeability of polymeric substances is expressed by the permeability coefficient P, which is a unique value (unit: c! (S, T, P
)an/al・sec・anHg) has been shown to be proportional to the differential pressure between the two sides of the membrane and the surface area of the membrane, and inversely proportional to the membrane thickness. Further, the selectivity of oxygen to nitrogen is determined by the ratio (PO2/PN2) of the permeability coefficient of oxygen (Po2) and the permeability coefficient of element (PN2).

Therefore, in practice, it is necessary to select a material with a large Po2, and to obtain a sufficient oxygen concentration, a polymer with a large P02/PN2 must be selected.Furthermore, in order to obtain a higher permeation rate, the membrane pressure must be selected. It is desirable to make the material thin, and it is also necessary that the material has high mechanical strength.

By the way, cellulose, polybutadiene, silicone rubber, poly(4-methylpentene-1), polyacetylene derivatives, etc. have been known as polymeric materials with high oxygen permeability, and all of them are used as oxygen-enriching membranes for combustion and medical treatment. Although it is being applied to oxygen inhalation devices and the like, it cannot be said that it has sufficient performance yet.

<Problems to be solved by the invention> Among the existing polymers, there are only a limited number of polymers that exhibit permeability with po of 10-9 or more, and only a few polymers such as polydimethylsiloxane, poly(4-methylpentene-1) ), natural rubber, polyacetylene derivatives, etc. Most of the other products have a PO□ of 10″″10 or less,
Not suitable for practical use. Also, the value of P O-/P N* is 3
~4, and conversely, as the value of PO□ increases, PO□
/PNz value tends to decrease. PO□ of polydimethylsiloxane has a large value of about 5X10-'' among polymers, but it is not only extremely difficult to create a thin film with weak strength <20 μm or less, but also PO□/
The value of PN is 2, lower than the others, and it cannot be used for applications that require high concentration oxygen-enriched air. Therefore, various efforts have been made to improve the above drawbacks, such as copolymerizing polydimethylcycloxane with polycarbonate, and blending polyvinyltrimethylsilane and polydimethylsiloxane, which have a cycloxane structure in the side chain. However, these P02=2
PO2 decreased to ~3X10-” and PO□/PN2
The value of is about 2 to 3, which is not much improved. On the other hand, poly(4-methylpentene-1) has strong mechanical strength, is chemically stable, and is well-balanced as a material, but it also has the disadvantage of a small value of POz / P N of about 3. be. Furthermore, natural rubber is P O, / P N
In addition to having a small value of , the carbon-carbon double bond in the main chain has a serious drawback of poor durability (particularly oxidation stability), making it unsuitable for practical use. Polyacetylene derivatives currently have the highest value of PO,=4 x 10-', but the value of PO□/PN2 is as low as about 1.7;
There are problems with chemical stability and mechanical strength, and improvements are desired.

<Object of the invention> The present invention improves the various drawbacks of the known materials as described above, and improves the oxygen permeability coefficient Po2 and the ratio P of the oxygen and nitrogen permeability coefficients.
The object of the present invention is to provide an oxygen selective permeation membrane that has excellent O□/PN (separation coefficient), good chemical stability, and high mechanical strength necessary to form a thin membrane.

<Means for Solving the Problems> According to the present invention, the following general formula (wherein R and R2 are the same or different groups, and at least one of R and R2 has 1 carbon number ~20
represents a fluorine-substituted alkyl group, and when only one of R and R2 represents a fluorine-substituted alkyl group, the other represents an alkyl group having 1 to 9 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) There is provided an oxygen selective permeable membrane obtained by polymerizing the fluorine atom-containing unsaturated dicarboxylic acid diester (hereinafter referred to as the first invention).
.

Further, according to the present invention, the following general formula % formula % (wherein R□ and R2 are the same or different groups, and at least one of R and Rt has a carbon number of 1 to 20
represents a fluorine-substituted alkyl group, and when only one of R□ and R2 represents a fluorine-substituted alkyl group, the other represents an alkyl group having 1 to 9 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) An oxygen selectively permeable membrane obtained by copolymerizing the fluorine atom-containing unsaturated dicarboxylic acid diester shown above and a copolymerizable vinyl monomer is provided (hereinafter referred to as the second invention).

The present invention will be explained in more detail below.

In the present invention, in both the first invention and the second invention, the following general formula % formula % (in the formula, R and R2 are the same or different groups, and at least one of R and R2 has a carbon number 1-20
represents a fluorine-substituted alkyl group, and when only one of R and R2 represents a fluorine-substituted alkyl group, the other represents an alkyl group having 1 to 9 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) A fluorine atom-containing unsaturated dicarboxylic acid diester is used. The fluorine-substituted alkyl group may contain a halogen atom other than a fluorine atom, and R and R2 may both be the above-mentioned fluorine-substituted alkyl group, or only one of them may be a fluorine-substituted alkyl group. However, the latter is preferred in consideration of polymerization reactivity. As the number of carbon atoms increases linearly, the polymerization reactivity tends to decrease, and as the number of carbon atoms increases in a linear manner, the polymerization reactivity tends to increase.When the number of carbon atoms in the fluorine-substituted alkyl group exceeds 20, When the number of carbon atoms in the alkyl group exceeds 9, the number of carbon atoms in the cycloalkyl group is 1.
If it exceeds 2, the polymerizability decreases, which is not preferable.

Examples of unsaturated dicarboxylic acid diesters having the above general formula that can be preferably used in the present invention include isopropyl-trifluoroethyl fumarate, isopropyl-hexafluoroisopropyl fumarate, tert-butyl-trifluoroethyl fumarate, and tert-butyl-trifluoroethyl fumarate.
Hexafluoroethyl fumarate, isopropyl-perfluorooctylethyl fumarate, tert-butyl-purfluorooctylethyl fumarate, di(trifluoroethyl) fumarate, di(hexafluoroisopropyl) fumarate, di(perfluorooctylethyl) Fumaric acid diesters such as fumarate, isopropyl-triple oroethyl maleate, isopropyl-
Hexafluoroisopropyl malate, isopropyl-
perfluorooctyl ethyl maleate, tart-butyl-trifluoroethyl maleate, tart-butyl-
Examples include maleic acid diesters such as hexafluoroisopropyl maleate, tert-butyl-perfluorooctylethyl maleate, di(trifluoroethyl)malate, di(hexafluoroisopropyl)malate, and di(perfluorooctylethyl)malate. be able to. Among these, trans fumarate is more preferable than cis maleate in terms of homopolymerization and copolymerization reactivity. Further, for example, when comparing the polymerization reactivity of ethyl-perfluorooctylethyl fumarate, isopropyl-perfluorooctylethyl fumarate, and tert-butyl-perfluorooctylethyl fumarate, the reactivity increases in the above order, Since the structure and reactivity of the ester group are related, in the case of homopolymerization and copolymerization, it is preferable to select the ester group depending on the purpose.

In the first invention of the present invention, the unsaturated dicarboxylic acid diester of the above general formula is homopolymerized, but in the second invention, a copolymerizable vinyl monomer is used and two or more components are copolymerized. Since polymerization can be easily controlled through copolymerization, it is easy to adjust the polymer, such as copolymer composition and molecular weight, and mechanical strength.

Solubility, softening temperature, etc. can be changed depending on the purpose.

Such copolymerizable vinyl monomers are not particularly limited as long as they can be copolymerized with the unsaturated dicarboxylic acid diester. Examples of such copolymerizable vinyl monomers include styrene.

Nuclear alkyl-substituted styrenes, nuclear halogen-substituted styrenes, α-methylstyrene, divinylbenzene, vinyl esters, vinyl ethers, allyl esters, allyl ethers, vinyl chloride, vinylidene chloride, acrylamide, N-alkylacrylamides, N , N'-dialkyl acrylamides, acrylic acid and methacrylic esters, acrylonitrile, imbutylene, 1
, 3-butadiene, isoprene and the like.

As for the weight ratio during copolymerization, it is desirable to use 1 to 50 parts by weight of the copolymerizable vinyl monomer to 100 parts by weight of the unsaturated diester dicarboxylic acid. If the copolymerizable vinyl monomer is less than 1 part by weight, the effect of adding the copolymerizable vinyl monomer will not be exhibited;
If the amount exceeds 0 parts by weight, the oxygen permeability of the copolymer will be significantly reduced, which is not preferable.

In either case of the first invention or the second invention, polymerization or copolymerization can be carried out by a radical polymerization method using a general radical polymerization initiator. For example, all conventionally known polymerization techniques such as bulk polymerization, solution polymerization, and suspension polymerization can be implemented. In this case, the temperature used in the single and copolymerization reactions is preferably in the range of 30 to 100°C, but even within this range, the polymerization temperature is 50 to 100°C.
If a temperature as high as 30 to 50° C. is selected, the molecular weight of the polymer or copolymer will be low, while if a low temperature of 30 to 50° C. is selected, a high molecular weight product can be obtained.

Examples of radical polymerization initiators that can be used within the above polymerization temperature range include diisopropyl peroxydicarbonate, diethylhexyl peroxydicarbonate, tart-butylperoxypivalate,
Isobutyryl peroxide, acetyl cyclohexyl ester sulfonyl peroxide, lauroyl peroxide, benzoyl peroxide, tert-butyl peroxyisobutyrate, azobisisobutyronitrile, azobisdimethylvaleronitrile, persulfates and persulfates-bisulfite Examples include salt-based initiators.

The amount of the radical polymerization initiator to be used is desirably 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the monomer or heptamer mixture. Furthermore, the polymerization time is about 1 to 72 hours, preferably about 2 to 48 hours, although it depends on the polymerization temperature and the type and amount of radical polymerization initiation.

<Effects of the Invention> The polymeric substance obtained by polymerizing or copolymerizing the unsaturated dicarboxylic acid diester having a fluorine atom obtained in the present invention can be formed into a film, and can be used in the conventional oxygen enrichment membrane field. Po2 and P Ox
/P N, both values exhibit excellent properties. Specifically, PO2-4,0×10″″~1,5X
10-7[a#(S,T,P)・am/aIt・sec
-aIIHg], PO2/PN = 3.2 to 4.5.

In addition, the polymer compound can be easily produced by known radical polymerization techniques, and the resulting polymer can be fractionated using a combination of appropriate organic solvents.

The polymer can be controlled to have a desired molecular weight.

Furthermore, the polymer or copolymer can be processed to a 1μ
It is also relatively easy to make the film thinner than m.

Furthermore, the polymeric substance not only has excellent acid resistance or alkali resistance, but is also thermally stable, and has sufficient properties for practical use.

<Examples> The present invention will be described in more detail with reference to Examples below, but the present invention is not limited thereto. Note that % is based on weight.

Iwaba ■Yo NidanUsing a fumaric acid diester having a fluorine-substituted alkyl group shown in Table 1 or a fluorine-substituted alkyl group that further contains a halogen other than fluorine, each monomer was prepared with an internal volume of 20 m2.
Log of each was taken in a glass ampoule of Q, and 0.1 of each organic peroxide shown in Table 1 was added as a radical polymerization initiator.
1.1.2-trichloro-1, 1.1.2-trichloro-1, The polymer was dissolved in 2,2-trifluoroethane, and this solution was poured into a large amount of methanol to precipitate the polymer.The polymer was separated every day, thoroughly washed with methanol, and then dried under reduced pressure to obtain the desired polymer.

All these polymers are again 1,1,2-trichloro-
After dissolving it in 1,2,2-trifluoroethane and creating a film with a thickness of about 10 μm by a solvent casting method, PO2 and PN2 were measured by a gas permeability measurement method using a vacuum method. Furthermore, the number average molecular weights of these polymers were measured using GPC. The results are summarized in Table 1.

(Left space below) Polymerization was carried out in an ampoule in the same manner as in Examples 1 to 7, except that an unsaturated dicarboxylic diester and a copolymerizable vinyl monomer were used at the composition ratios shown in Table 2. , processing, measurement 1 analysis was performed.

The copolymer composition was calculated from the results of NMR spectrum and elemental analysis. These results are shown in Table 2.
Shown below.

(Margin below)

Claims (1)

[Claims] 1) The following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R_1 and R_2 are the same or different groups, and at least one of R_1 and R_2 has 1 to 1 carbon atoms. 20 fluorine-substituted alkyl groups, R_1 and R
When only one of _2 represents a fluorine-substituted alkyl group, the other is an alkyl group having 1 to 9 carbon atoms or 3 to 1 carbon atoms
An oxygen selective permeation membrane obtained by polymerizing a fluorine atom-containing unsaturated dicarboxylic acid diester represented by (2) (representing a cycloalkyl group). 2) The following general formula▲ Numerical formula, chemical formula, table, etc.▼ (In the formula, R_1 and R_2 are the same or different groups, and at least one of R_1 and R_2 is a fluorine-substituted alkyl group having 1 to 20 carbon atoms. and R_1 and R
When only one of _2 represents a fluorine-substituted alkyl group, the other is an alkyl group having 1 to 9 carbon atoms or 3 to 1 carbon atoms
An oxygen selectively permeable membrane obtained by copolymerizing a fluorine atom-containing unsaturated dicarboxylic acid diester represented by (2) (representing a cycloalkyl group) and a copolymerizable vinyl monomer.