JPH084729B2 - Semipermeable membranes based on specific tetrabromobisphenol type polyesters - Google Patents

Description

TECHNICAL FIELD The present invention relates to a semipermeable membrane of a polyester of tetrabromobisphenol as a main nucleus component of the polyester and an aromatic dicarboxylic acid. The present invention also provides for the selective permeation of a fluid mixture containing at least one component in admixture with another component, particularly for oxygen / nitrogen and carbon dioxide / methane separations. It also relates to methods of using the membrane.

BACKGROUND OF THE INVENTION Dialysis membranes that are capable of selectively permeating one component of a fluid mixture, either liquid or gas, can be a convenient, highly advantageous in the art for performing fluid separations. It is considered to be an effective means. The dialysis membrane can achieve an acceptable level of selectivity or degree of separation of the gas or liquid contained in the fluid feed stream for practical commercial operation, while at the same time achieving the desired degree of component separation. It must be possible to achieve very high productivity or speed.

Various types of dialysis or semipermeable membranes that perform various fluid separations are known in the art. Such membranes have been classified as isotropic or homogeneous, or complex or asymmetric types, the structures of which are well known to those skilled in the art.

As the benefits of dialysis and semi-permeable membranes have become more and more recognized, the performance requirements have likewise increased and the impetus to find new membranes for more applications has continued to grow. There is. Due to these requirements, the technology moves towards extremely thin membranes with the desired permeation characteristics without sacrificing the membrane's separation or selectivity characteristics or achievable permeation rates, or productivity or separation. Came to.

At present, dialysis membranes are used in a wide range of materials, such as natural and synthetic polymers such as rubber, polysiloxanes, polyamines,
Brominated polyphenylene oxide, cellulose acetate, ethyl cellulose, polyethylene, polypropylene, polybutadiene, polyisoprene, polystyrene,
Polyvinyl, polyester, polyimide, polyamide,
It is known to be made from polycarbonate and many other materials.

The oyster table shows some published diameters in various gases that are usually separated by polymer membranes.

In the case of oxygen and nitrogen, the dimensional difference is rather small, so most polymer membranes that are commercially used to separate nitrogen and oxygen prevent gasses, such as oxygen, from flowing through the membrane. Has a hindering molecular structure. As such, these polymer membranes must be extremely thin, typically 200 to about 10,000 angstroms, and preferably less than 2,000 angstroms, in order to make the separation economically feasible. The thinner the membrane, the faster the permeate can be transported through the membrane.

Technology and physical factors limit how thin coatings of membrane or composite membranes can be made, and thus, novel novel permeation rates with greater permeation rates without significantly sacrificing the ability to separate the desired gas mixture. It is advantageous to develop membrane polymers. However, numerous gas permeation coefficients and gas separation data in the literature (eg, Polymer Handbook, 2nd Edition, John Willie and Sons, 1975) usually change the permeability of gases such as oxygen, altering polymer structure. It shows that the latter increases the separation properties of the latter, namely the ability to separate oxygen and nitrogen. The data also show that, depending on the state of the art, certain structural features remain constant even with some minor changes in the chemical structure of the membrane of one polymer class, eg polyester or polycarbonate. Even show that it is not practically possible to predict the gas permeation rate or gas selectivity. The literature also shows that changes in the membrane itself, the structure of the membrane is isotropic, the asymmetry are complex, or the thickness of the membrane can also significantly affect the permeation rate and selectivity. The conclusions drawn from the literature predict that in many membrane patents, many arbitrary modifications to the basic polymer structure of one or more polymer classes will predict the utility of another structure that has not been studied. That is not to teach enough. Clearly, careful consideration needs to be taken in defining both the chemical and physical structure of the membranes suitable for use in the gas separation process.

Many of the factors that influence gas permeability have become largely known for over 20 years, but even the magnitude of these factors and the direction of the combination of these factors in a particular polymer membrane are quantitatively determined. What can be predicted has not succeeded to this day. Researchers in the 1950s and 1960s found that attraction between polymer chains, packing density, rotation around single bonds in polymer chains, relative rigidity (aromatic structure) or flexibility (fat) of polymer chains. I knew that (group structure) affects gas permeability. Rigid, highly aromatic polymer structures such as bisphenol A polycarbonate were found in the 1960s and
It was investigated in the early 1970s in an attempt to obtain the best combination of gas permeability and gas separation or selectivity. For example, significant values of gas selectivity for oxygen / nitrogen have been obtained, but this has not been combined with sufficiently high gas permeability, and there has been a continuing need to achieve higher gas permeability.

Published August 1975 by Pilato and others (Ame
r.Chem.Soc.Div.Poym.Chem., Polym., Prepr., 16 (2)
(1975) pp. 41-46) modify rigid aromatic polymer structures such as polysulfones, polycarbonates, polyesters containing certain bisphenol-phthalate polyesters which are not within the scope of the present invention to include helium / methane and carbon dioxide / It was shown that it is possible to increase the gas permeation rate without significantly reducing the methane separation. More data by Pyrado et al. Show that tetraisopropylbisphenol A or tetramethylbisphenol L (based on limonene + dimethylphenol) was added to these polymers in an attempt to increase gas flux to improve gas selectivity. It shows that it has decreased. It is thus clear that even in rigid polymer systems it is true that increasing gas permeability leads to a reduction in gas selectivity, a general trend mentioned in the polymer handbook. Based on this work and the other publications mentioned above, it is clear that further efforts were needed to achieve higher permeabilities while retaining high gas selectivities.

In August 1975, another unusually broad disclosure of US Pat. No. 3,899,309 (July 29, 1980, reissue patent 30,351
No.) appeared. The U.S. patent is a highly aromatic polyimide,
It described polyamides and polyesters.
The patent claimed to combine backbone non-linearity, highly aromatic structure, and prevention of free rotation around the backbone single bonds leading to increased gas permeability. The disclosure is broad and teaches those skilled in the art appropriately or sufficiently to allow one to determine which particular structure will result in more desirable gas permeability and selectivity without undue research and experimentation. Not not.

US Patent 3,899,309 (issued on August 12, 1975)
Reissue of HH Horn (Hoehn), etc. May 1, 1976
U.S. Reissue Patent No. 30,351, filed on August 8, discloses a wide range of aromatic polyimide, polyester, and polyamide separation membranes. The invention broadly described and claimed in these patents requires that the polymeric aromatic imide, aromatic ester or aromatic amide repeat unit must meet certain requirements, namely: ) Two main chain single bonds containing at least one rigid divalent subunit and extending therefrom are co-linear (coli
not near), (b) unable to sterically rotate 360 ° around one or more of the main chain single bonds, (c) more than 50% of the atoms in the main chain Is a member of an aromatic ring.

These requirements are set out in the abstract of the reissued patent, column 1, lines 40 to 53, claim 1 and all the claims dependent on claim 1.

The method for obtaining the requirement (a) is 2 columns 51 to 68, the requirement (b) is 3 columns 1 to 28, and the requirement (c) is 3
Columns 29-56 are listed, and 3 columns 57-68 explain how the requirements were determined in the example. in this way,
In order for a polymer to be within the scope of the invention described and claimed in Reissue Patent No. 30,351, it must meet all three criteria or requirements set forth in the patent. A polymer cannot be considered within the scope of the invention if it cannot meet all three requirements. The requirement (b) of reissue patent No. 30,351 is that the membrane is
Limited to those polymers in which the polymer chain contains at least one rigid mono-linear band between the rigid subunits (the polymer chain is sterically hindered to rotate 360 ° around the subunit), and It describes sterically how this can be verified by a well-identified and readily available molecular model kit. As a result, polymer structures assembled from the identified kit that are not specifically prevented from rotating 360 ° cannot be considered within the scope of Reissue Pat. No. 30,351.

Reissue patent 30,351 has 2 columns, 21-34 lines, 6 columns, 26-56 lines,
Column 7, lines 19 to 29 and Lines 42 to 53; Column 11, line 62 to Column 12, line 68 (Table II
I and IV) define the polyesters claimed to meet the requirements (a), (b), (c), and show specific examples of polyesters and their membranes in Examples 1-5, 9-12 and 22. There is. The use in the process of polyester membranes is described in claims 1 and 8 to 13, and claims 12 and 13 are overlapping. In column 4, lines 10-15 and lines 43-46, it is stated that the membrane of the invention is in the form of a film or a hollow fiber, the membrane being a homogeneous membrane (column 4, lines 47-49).
Line) or an asymmetric membrane (column 4, lines 49-54).

US Patent No. 3, issued on July 2, 1974 to HH Horn,
In 822,202, the same polyimide, polyester and polyamide polymers are disclosed as being suitable for use as the membrane, but in this patent the membrane is treated under reduced pressure in an air or inert gas environment at 150 ° C. Heat treatment is performed in the temperature range just below the conversion point. This leads to the formation of a true asymmetric membrane. There is no mention of composite membranes throughout U.S. Pat.No. 3,822,202, and the only example of a polyester membrane in that patent is Example 21, which uses a 2.15 mil (0.0546 mm) thick air-dried flat film. There is. It should be noted that U.S. Pat. No. 3,822,202 does not specifically disclose tetrabromobisphenol and polyesters of aromatic dicarboxylic acids or their use in a fluid separation process.

The most recent U.S. Pat. No. 4,822,382, issued to JK Nelson on April 18, 1989, discloses one or more poly (terolamethyl) bisphenol A phthalates for use in separating gas mixtures. A separation membrane, in particular a composite membrane, having a separating layer consisting of The patent does not disclose any other polyester within this class, and the data in the examples show that oxygen separation rates are low in air separation.

European Patent Application No. 0242,147, published by Aneda et al. On October 21, 1987, discloses a gas separation membrane based on a bisphenol-derived polycarbonate polymer and its use in a gas separation membrane process. ing. Membranes are claimed to have unique applications in separating oxygen and nitrogen, but they are not polyesters.

European patent application 0244146, such as Anand et al., Published on November 4, 1987, gasses membranes and polymers based on polyestercarbonate polymers whose polymer backbone is tetrabromodiphenenol-based residues. Although disclosed for use in a separation process, the membrane is not polyester.

Both of these European patent applications have the following carbonate groups: Is based on a polycarbonate polymer containing in the polymer chain. The presence of this carbonate bond is an essential element of the disclosed invention, the ester group: Should be distinguished from polyesters containing

Ueno Shoji and other Japanese patent applications published on June 14, 1978 53
-66880 discloses membranes based on aromatic polyesters made from aromatic dicarboxylic acids and bisphenols of the following structure: Wherein R _1-4 and R ′ _1-4 are hydrogen, halogen or hydrocarbon; X is one of —O—, —SO ₂ —, —CO—, —S—, alkylene or alkylidene. Is.

The bisphenols disclosed and considered suitable all contain one of the defined X groups as a linking or bridging group. The application does not disclose or suggest any bisphenol compounds in which the linking group contains either a halogen atom or a divalent cycloalkyl group.

Composition of the Invention The invention comprises (1) 80 mol% or more of (a) isophthaloyl dichloride and / or 4-bromoisophthaloyl dicleloride, as more fully defined herein below. And (b) tetrabromobisphenol of the following general formula which is reacted with 20 mol% or less of terephthaloyl dichloride and / or 2-bromoterephthaloyl dichloride: At least 50 mol% or more, preferably 80 mol% or more, most preferably 100 mol%, or (2) (a) isophthaloyl dichloride and / or 4-
30 mol% or less of bromoisophthaloyl dichloride and (b) at least 50 mol of said tetrabromobisphenol (I) reacted with 70 mol% or more of terephthaloyl dichloride and / or 2-bromoterephthaloyl dichloride % Or more, preferably 50 mol% or more, most preferably 100 mol% based on an improved gas separation membrane consisting mainly of polyester or copolyester. Alternatively, the free acid or ester or salt form of the phthaloyl compound can be used to make the polyester. The present invention also includes the use of the membrane in oxygen and nitrogen separation and carbon dioxide and methane separation processes.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a new and improved polyester dialysis membrane having excellent oxygen / nitrogen and carbon dioxide / methane gas separation with high oxygen and carbon dioxide permeability.

Methods for making polyesters are well known and several procedures can be used. That is, it is known that a polyester can be produced by reacting a dihydroxy compound with an aromatic dicarboxylic acid or an ester-forming derivative thereof, such as an acid chloride. The present invention is not a part of the present invention for the method for producing polyester constituting the gas separation membrane, and any polyesterification process can be used. A typical procedure used to prepare the polyester film of the present invention is to react the tetrabromo-bisphenol compound (I) with terephthaloyl chloride, isophthaloyl chloride or a mixture thereof. Such a process has been used by Chamer and others.
It is disclosed in U.S. Pat. No. 3,388,097 issued Jun. 11, 1968. In the case of polyesters based on 50 mol% or more of tetrabromobisphenol (I) for oxygen / nitrogen separation (eg air separation), the phthaloyl compound is in the molar ratio of terephthaloyl to isophthaloyl compound of 80:20 to 0: 100. , Preferably 20:80 to 0: 100, most preferably 0: 100. In the case of polyesters based on 50 mol% or more of tetrabromobisphenol (I) for carbon dioxide / methane separation, the molar ratio of terephthaloyl to isophthaloyl compound is from 100: 0 to 0: 100, preferably from 90:10. 70:30, most preferably 85:15 to 75:25. In addition, as is known to those skilled in the art, other suitable aromatic dicarboxylic acids, acid chlorides or esters can be used in the small amount polyesterification process, and further, small amounts of the aromatic dicarboxylic acid component can It can be replaced by a dicarboxylic acid. The small amounts added should be such that they do not have any significant detrimental effect on permeability and / or selectivity. Furthermore, mixtures of tetrabromobisphenols of formula I with small amounts of other bisphenols or other aromatic and / or aliphatic diols can be used,
Up to about 10 mol% of tetrabromobisphenol (I) can be replaced with another bisphenol or the diol. Preferred polyesters are those prepared by condensation polymerization of tetrabromobisphenol of formula I with terephthalic acid, isophthalic acid or mixtures thereof, or salts or esters thereof such as acid chlorides. New York,
John Willie and Sons, Interscience Division Publishing, Editing by Mark, etc.Encyclopedia of Polymer Science and Technology, 1969, 11
Vol. 1, pp. 168-168, describes a number of known processes for making polyesters. Given that these polymers are widely known, neither the particular reactants described above nor the reaction conditions required for the polyesterification reaction need be described in any detail. This technical document is well known to those skilled in the polyester art.

The gas separation membrane of the present invention has the following general formula: tetrabromobisphenol: (In the formula, R'is Alternatively, it is a divalent cyclododecyl) and comprises a thin layer predominantly of a polyester or copolyester.

The diol component of the polyester or copolyester is more than 50 mol% of tetrabromobisphenol (I),
Preferably, it constitutes at least about 80 mol%, and the structure (I) can be admixed with other bisphenols of the following structure (II) to reach 100 mol%. This allows the diol to be a mixture of more than 50 mol% tetrabromobisphenol (I) and less than 50 mol% bisphenol of the general formula: Here, R ″ is methyl or chlorine.

The tetrabromobisphenol (I) used to make the polyester gas separation dialysis membrane constitutes at least 50 mol% or more of the dihydroxyl compound used to make the polyester as described above. The polyester or copolyester is the following reaction product: (1) Tetrabromobisphenol (I) at least
50 mol% or more and (a) isophthaloyl dichloride and / or 4-bromoisophthaloyl dichloride as a dicarboxylic acid compound 80 mol% or more and (b) terephthaloyl dichloride and / or 2 -Bromo terephthaloyl dichloride reacted with 20 mol% or less, or (2) tetrabromobisphenol (I) at least 50
Mol% or higher and (a) isophthaloyl dichloride and / or 4-bromoisophthaloyl dichloride 25 mol% or lower and (b) terephthaloyl dichloride and / or 2-bromoterephthaloyl dichloride Reacted with 75 mol% or more.

The polyester gas separation membrane of the present invention contains as a main repeating unit having the following structural formula: Wherein R is hydrogen or bromine and x is at least about 20 up to about 200 or more, preferably about 25 to about 175.
Is an integer having a value of. Polyester weight average molecular weight about 20,000 to about 150,000, most preferably about 30,000 to about 12
It is preferred to have 5,000.

The gas separation membrane of the present invention can be a dense film or any form known to those skilled in the art, and further can be a composite, asymmetric or homogeneous or isotropic membrane. . The membrane can be spiral shaped, flat sheet, tube shaped or other shapes, as well as hollow fiber shaped. Those skilled in the art are aware of the many methods available to make them and how to make membranes in any of these shapes. The preferred membranes of the present invention are asymmetric or composite membranes, wherein the separation layer has a thickness of less than 10,000 Angstroms,
It is preferably less than 5,000 angstroms, most preferably about 200 to about 2,000 angstroms.

Isotropic and asymmetric types of membranes usually consist essentially of a single dialysis membrane material capable of selective oxygen / nitrogen and carbon dioxide / methane separation. Asymmetric membranes are distinguished by the presence of two or more morphological regions within the membrane structure. One such region comprises a relatively dense thin semipermeable skin capable of selectively permeating at least one component from a gas mixture containing at least one component in admixture with another component, The other region comprises a less dense, porous, essentially non-selective support region that serves to prevent the thin skin regions of the membrane from breaking during use. Composite membranes typically consist of a thin layer or coating of polyester translucent membrane overlaid on a porous substrate.

Flat sheet membranes are cured by casting the solution from a polyester solution in a suitable solvent such as methylene chloride to evaporate the solvent, then drying the cast film under reduced pressure or at elevated temperature, or a combination of both. Made easy to make. Such thin film membranes have a thickness of about 0.5 to about 1
It can range from 0 mils (0.013 to 0.025 mm) or higher, preferably from about 1 to about 3 mils (0.025 to 0.076 mm).

Flat sheet membranes are usually not the preferred commercial form. For large scale commercial applications, hollow fiber dialysis membranes are usually more desirable when processed as a module due to their significantly higher surface area per volume.
Porous hollow fiber dialysis membranes include a porous hollow fiber support material having a dialysis membrane layer on its surface, methods for their production are well known (eg, New Jersey, Noise Data Corporation, J. Scott, See Hollow Fibers Manufacture and Applications, 1981, p.264).

The tetrabromobisphenol type polyester dialysis separation membranes of the present invention exhibit a separation factor of at least about 5.6 higher for oxygen than nitrogen from an air mixture, associated with a permeation rate or flux of at least about 4, and contain carbon dioxide and methane. It exhibits a higher separation factor for carbon dioxide than methane in the mixture. The ability of these membranes to separate these components with such a high combination of both separation factor and permeation rate was totally unexpected, and more than the results often shown by many existing membranes in the art. Are better. That is, for example, the polycarbonate membrane disclosed in EPO 0242147 and the polyester carbonate membrane disclosed in EPO 0244126 have relatively low permeation rates. The combination of high selectivity and high permeation rate within the membranes in these EPO applications is not shown. EPO 02441
The data in the table of No. 26 show a low oxygen transmission rate P0.96 to 1.23 Barrer for polyester carbonate membranes in combination with a separation factor or selectivity for oxygen over nitrogen of 6.7 or 7.2. These values are not considered in the art as a high combination of the two values. Similarly, EPO 0242147
The data in Table 1 of the publication show a low oxygen permeation rate P0.8-1.448 Barrer for polycarbonate membranes in combination with a separation factor or selectivity for oxygen over nitrogen of 5.4-7.4, again with a combination of the two higher values. Is unthinkable.

The inventive tetrabromobisphenol polyester membrane exhibits a combination of high selectivity and high permeation rate, as shown by the experimental data in the examples. As can be seen in the data obtained and reported in the examples below, the membranes of the present invention have an oxygen permeability P of from about 4.7 to about 11.8 Barrer and a separation factor or selectivity for oxygen over nitrogen of about 5.6 to about 7. The combination with and is truly a combination of two higher values.

Tetrabromohexafluorobisphenol A (I)
It was found that increasing the percentage of isophthalic acid to terephthalic acid in the compound increased oxygen / nitrogen selectivity over polyesters with higher amounts of terephthalic acid and did not result in oxygen permeabilities below 4.5 Barrer. Preferably, the isophthalic acid ester content should be 80 mol% or more of isophthalic acid ester, most preferably 100 mol%. In contrast, the carbon dioxide / methane separation surprisingly uses the same tetrabromohexafluorobisphenol with a terephthalate content of about 75 mol%.
Or higher and isophthalate content of about 25
The optimum combination of resolution and permeability is achieved at mol% or below. When the terephthalate content is high, the efficiency of oxygen / nitrogen separation is significantly lower.
Thus, for oxygen / nitrogen separation, a high isophthalate content is preferred, while for carbon dioxide / methane separation, a high terephthalate content is preferred.

Compounds of formula (I), eg tetrabromohexafluorobisphenol A 50 mol% or higher, preferably 6
Copolyesters based on 0 mol% or more and one or more other bisphenols (Compound III in the table) are also useful gas separation membranes in comparison to the tetrabromobisphenol polyesters described above. Intrinsic permeability and gas separation properties may be imparted less favorably. However, many of these copolymers have slightly better solubility characteristics for coating composite membranes of polysulfone hollow fibers as described in U.S. Pat. Sacrifices slightly and usually improves transparency. Solubility of polyesters in certain solvents and solvent systems is important because polysulfone hollow fibers can be attacked by many common solvents used to dissolve many membrane polymers. Thus, even though polyesters have excellent inherent content and permeation properties, their usefulness is limited if they cannot be coated onto substrates such as polysulfone or other porous hollow fiber substrates. It will be. As a substrate for these coatings, chemically resistant porous hollow fibers are ideal if price, coatability and other factors are overcome to make them useful for composite membranes. It is arguable that asymmetric hollow fiber membranes can be made entirely from these polymers, but the cost is prohibitive. Different methods than solution application may be possible,
Need to be developed in the future.

A polyester based on tetrabromohexafluorobisphenol A was previously disclosed in Horn patent 3,899,309, which, due to the above structure
It does not argue or suggest that the unexpected and unpredictable improvements resulting from nitrogen and carbon dioxide / methane separation are achieved. Claim 11 of US Pat. No. 3,899,309 discloses an isophthalate / terephthalate polyester based on tetrabromohexafluorobisphenol A. Column 8, lines 23-35 show a preferred isophthalate / terephthalate composition ratio of 70/30.
It is said that. Moreover, tetrabromohexafluorobisphenol A is not included in the list of preferred diols (bisphenols) in column 16, lines 17-18.

The data in the table below show the incomparable combinations of very good oxygen / nitrogen separation factors and high oxygen gas permeabilities for certain polyesters and copolyesters as compared to the examples known in the prior art.

In the table, run 7 has a comparable oxygen / nitrogen separation factor of 6.7 and a high oxygen permeability of 5.25 Barrer, compared to run 1 of tetrabromohexafluorobisphenol A polyisophthalate.
However, the oxygen permeability is only 1.87. If the other factors are equal, the latter membrane is almost 3 times larger than the former one.
With the double membrane area, the former membrane is decisively economically advantageous. Other examples in the Horn reissue patent have much lower gas selectivity and do not compete with Run 1 in the table.

Carbon dioxide / methane separation has been difficult because the factors leading to high carbon dioxide permeability result in low carbon dioxide / methane separation factors. The table below shows that commercially available membranes based on cellulose acetate and polysulfone give good separability for this gas pair, but their low permeability for carbon dioxide makes them commercially more economical to operate. Indicates that it needs to be higher. While tetramethylbisphenol A polycarbonate appears to have the best combination of permeability and separation factors reported in the literature, it is not as good as the tetrabromohexafluorobisphenol (I) polyesters of this invention.

The structure of the present invention exhibits a very high permeability and a significant combination of carbon dioxide / methane separation based on pure / mixed gas measurements. With an optimal structure for oxygen / nitrogen separation, tetrabromohexafluorobisphenol A high isophthalic acid ester yields the best separation and permeability combination. Surprisingly, exceptionally high carbon dioxide permeabilities are found at an isophthalic acid / terephthalate ratio of 25/75 with essentially no significant reduction in gas selectivity for carbon dioxide / methane. The 25/75 isophthalic acid / terephthalic acid ester structure thus significantly doubles carbon dioxide permeability from P = 20.0 to P = 42 for a 100% isophthalic acid ester structure without significantly reducing gas selectivity. What I did was unexpected.

I Compound I from Experiment 1 below I Tetrabromohexafluorobisphenol of the Invention
Note that the A25 / 75 isophthalic acid / terephthalate ester film has significantly improved properties over other known polymer films and the same polyester based on 100% isophthalic acid.

Although data are limited for various combinations of isophthalic acid / terephthalic acid ester ratios in the copolymer, permeation was achieved by varying the isophthalic acid / terephthalic acid ester ratios as shown in the experimental section by analogy with bisphenol and the above example. It shows that the degree and the gas separability can be changed.

The reduced viscosity of the polyester was determined at 25 ° C. using a polymer solution containing 0.200 g of polymer per 100 ml of chloroform and calculated by the following formula: Here, A is the time taken for the sample of the chloroform solution to move in the viscometer, B is the time taken for the chloroform to move in the viscometer, and C is the weight of the sample of the chloroform solution. Is.

The polyester was a film formed with a reduced viscosity in chloroform of about 0.25 and above. For the gas dialysis process, polyesters having viscosities of about 0.25 or greater result in reasonably strong films of about 2 to about 5 mils (0.05 to 0.13 mm) thick. Preferred viscosities are about 0.25 to about 1.6, most preferably about 0.45 to about 1.3. The film thickness is about 1
~ About 10 mils (0.025 ~ 0.25 mm), preferably about 2 to about 5
It can be in the range of mil (0.05-0.13mm).

Porous hollow fiber polysulfone substrates are useful in making composite membranes. Porous polysulfone hollow fibers are prepared from a solution of polysulfone in a solvent / non-solvent mixture,
As known in the art, I. Cabass (Cabass)
o) etc. are “Composite Hollow Fiber Membrane”, Journal of Applied Polymer Science,
23, 1509-1523 and July 1975, Intalia
PB 248,666 "Research and Development of NS-1 and Related Polysulfone Holo-Fibers for Reverse Osmosis Desorination of PB Made for US Department, Office of Water Research and Technology, Contract No.14-30-3165 It is made using the procedure described in "Seawater". Well-known tube-in-
Using the tube jet technique, water at about room temperature is the outer cooling medium for the fibers. The cooling medium in the central bore of the fiber was air. After cooling, it is common to remove the extensively washed pore-forming material. After washing, the hollow fibers are passed through a hot air drying oven to dry at elevated temperatures.

It is advantageous to make the walls of the porous polysulfone hollow fibers sufficiently thick so that they do not require special equipment to handle the fibers and can be conveniently formed into cartridges. The outer diameter of the porous polysulfone hollow fiber is about 1 mil (0.025 mm) or less to about 100 mil (2.
5 mm) or more, preferably about 2 to about 80 mils (0.0
5 to 2.0 mm). The wall thickness of porous polysulfone hollow fiber is about 0.1 to about 25 mils (0.0025 to 0.6
4 mm) or more, preferably at least about 0.2 mils (0.005 mm) to about 20 mils (0.51 mm). The spun polysulfone fibers are generally considered to be substantially isotropic, but some degree of asymmetry is usually present. The porosity of the hollow fibers can be changed by annealing techniques, especially by heat annealing. This is conventionally done by drying dried porous polysulfone hollow fibers in a hot air oven at temperatures from about 160 ° to near the glass transition temperature of polysulfone (195 ° to 200 ° C), less than about 30 seconds, preferably about 10 seconds. It will take place throughout the following times.

The gas permeability or the permeation rate P of the flat film membrane evaluated in the following examples was measured at 25 ° C. by placing a small disk of a polymer membrane film of known thickness in a constant volume-variable pressure permeation cell. . Both sides of the membrane were degassed under vacuum overnight and then one side of the membrane was exposed to ² psig (1.8 kg / cm ² G) gas. The permeate gas was collected in a receiver on the other side of the membrane and the gas pressure was measured using a sensitive transducer. The pressure increase as a function of time was recorded on a strip chart and the data was used to determine the steady state permeation rate P. The transmission rate P is reported in Barrer units. Ba
The rrer unit is as follows: (cm ³ (STP) cm / cm ² −sec · cmHg) × 10 ⁻¹⁰ .

Membranes were made from 2-10 wt% polymer solution in methylene chloride and had a thickness of about 2 to about 10 mils (0.05-0.25 mm). The solvent was evaluated under reduced pressure at 40 ° C. and finally at 125 ° C. for 5 days and then evaluated.

Experiments 1-5 show the process for making the intermediates used to make the polyester membranes used in the examples of the invention. The preparation of the compound was confirmed by nuclear magnetic resonance analysis of both proton and C-13 and melting point.

Experiment 1 The procedure used was Makromo by FS Holahan
Chem., 103 (1), pp. 36-46 (1967).

In a 2-liter three-necked flask equipped with a stirrer, addition funnel, condenser, thermometer, and 10% sodium hydroxide trap, 4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) 201.76 g of ethylidene] bisphenol, 300 ml of ethanol and 140 ml of water were added. In this reaction mixture,
124.84 ml of bromine was added with good stirring at 15 ° C over 3 hours. The reaction mixture was stirred overnight. About 3 g of sodium thiosulfate was added to decompose excess bromine. Distilled water 3
The product was precipitated by the addition of liters. The product was filtered, washed 3 times with water and dried in a vacuum oven at 80 ° C. The yield of 4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dibromophenol] (Compound I) was 388 g. The product was recrystallized from chlorobenzene to give an overall yield of 87%.
Melting point = 256.5-258 ° C. Literature melting point = 256-257 ° C.

Experiment 2 A 1 liter three-necked round bottom flask was equipped with a stirrer, a chlorine gas inlet equipped sparge tube, a dry ice-acetone condenser and an outlet leading to a 10% sodium hydroxide trap, and 4,4 '-(hexafluoroisopropyl Redden)
67.25 g of diphenol and 600 ml of dichloromethane were charged, and the mixture was cooled in an ice-water bath to about 20 ° C. Chlorine gas was sparged in at a rate that maintained a saturated solution and the temperature was adjusted to about 20 ° C. After 8 hours, a rotary evaporator was used under reduced pressure to remove dichloromethane and remove 4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dichlorophenol. ] (Compound II) 88 g (yield 93
%) Was obtained. Recrystallized in methanol / water, melting point 225
The purified product at ˜227 ° C. was obtained in 80% overall yield. (Melting point 223 ° -224 ° C. in literature-see Experiment 1).

Experiment 3 In a 1000 ml three-necked round bottom flask equipped with an addition funnel, a thermometer, a thermowatch temperature controller, and a dry ice / acetone condenser insulated with glass wool, 457.5 g of 2,6-dimethylphenol and 75 g of methanesulfonic acid were added. In addition, the reaction mixture was heated to 95 ° C. Then 75 g of 1,1,1,3,3,3-hexafluoro-2-propanesesquihydrate was added dropwise over 1 hour. Heat the reaction mixture to 148 ° C for 2 hours
I made it. In a further 3 hours the temperature was raised to 160 ° C. The progress of the reaction was followed by isolating 10 g of the sample, removing the acid with water and sodium bicarbonate to remove dimethylphenol with methylene chloride, drying and measuring the melting point. After 15 hours at 160 ° C, the melting point was 208 ° -217 ° C. After 22 hours at 160 ° C, the melting point was 221 ° -223 ° C. 40 warm semi-solid
The reaction mixture was worked up by pouring into a 00 ml beaker and washing with 2000 ml of water 5 °. Then 400 ml of methylene chloride was added and the sample was washed 3 more times with 20 ml of water. A few grams of sodium bicarbonate were added to give complete acid neutralization. The methylene chloride layer was separated with some solids and solvent,
Residual dimethylphenol was removed by vacuum on a rotary evaporator up to 165 ° C. The yield of 4,4 ′-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dimethylphenol] (Compound III) was 11
It was 7 g. Wash the sample with 500 ml of methylene chloride and 500 ml of toluene, and finally with 150 ml of methylene chloride,
Dry in a vacuum oven at 80 ° C. Yield 64g. Melting point = 219 ° -221.5 ° C. Document U.S. Pat.No. 4,358,624 (11/9 /
82) melting point = 218-219 ° C.

Experiment 4 Mechanical stirrer, gas sparger, thermometer, thermowatch temperature controller, hydrogen chloride lecture bottle connection, 10% sodium hydroxide trap for hydrogen chloride escaping from the reactor and ice to keep temperature at 20 ° C. 3000 with bath
Cyclododecanone 273.45 in a 3-necked round-bottomed 3-mL flask.
g, 2,6-Dimethylphenol 837.0 g, n-octyl mercaptan 27.0 ml and methylene chloride 315.0 ml were added. 7 1/2 of hydrogen chloride in solution at a rate to obtain a saturated solution
Allowed to sparg for hours. The solid content obtained after 2 days of warming was filtered and washed 4 times with 2000 ml of methylene chloride. Recrystallized twice from toluene to give bisphenol 1,
1-bis (3,5-dimethyl-4-hydroxyphenol)
Cyclododecane (Compound IV), melting point = 240.5-242.5 ° C. was obtained with overall yield of 19.7%. Reference US Pat. No. 4,554,309 Melting point = 239 ° to 240.5 ° C.

Experiment 5 Procedure for making 4-bromoisophthaloyl and 2-bromoisophthaloyl chlorides from their corresponding acids.

In a 500 ml three-neck round bottom flask equipped with a mechanical stirrer, dropping funnel, condenser, silicone oil heating bath, nitrogen inlet and outlet to sodium hydroxide scrub solution, 100 g (0.40) of monobromoiso- or monobromo-terephthalic acid was added.
8 mol) and 1 ml of pyridine were added. Then thionyl chloride
202 ml (328.5 g, 2.77 mol) was added dropwise. When all the materials were added, the mixture was refluxed for 24 hours, during which time hydrochloric acid and sulfur dioxide were evolved. During this time a yellow solution was obtained. Upon standing overnight, no crystals developed indicating the diacid chloride was a liquid. To distill excess SOC1 _2, oily wears Yellowness crude seminal product 7-fold excess of n-
Boiled with hexane. The hot solution was passed through to remove unreacted diacid. Hexane was distilled off. Sample 3-4m
It was purified again by distillation at 125-132 ° C. under reduced pressure of mHg.

In a separate experiment, about 70 g each of yellowish 4-bromoisophthaloyl chloride and an oily-appearing purplish-colored 2-bromoterephthaloyl chloride were obtained and used in the direct polymerization.

The examples below serve to further illustrate the invention. The aromatic dicarboxylic acid derivatives used in the examples were terephthaloyl chloride and isophthaloyl chloride or mixtures thereof, unless stated otherwise. Parts are by weight unless otherwise indicated.

Flat membrane 3 to 7% by weight of polymer in methylene chloride
Made from a solution of. A portion of the solution was poured onto a glass plate and left covered with an aluminum lid overnight at ambient conditions.
The film was peeled from the plate and dried in a vacuum oven at 40 ° C for one day. The film is then further vacuumed at 125 ° C.
At 5 days, and the thickness was measured. The membrane was tested for pure gas, oxygen and nitrogen permeability at 25 ° C and 2 atmospheres.

The polyester was prepared by known interfacial polymerization procedures with mechanical stirring in a Waring blender and in a three neck round bottom flask and cooling with an ice bath. The stirring speed was not constantly monitored, but was usually about 1000 rpm. The rate of acid chloride addition was based on the control of the exotherm. Everything else, as is well known in the literature ("Condensation Polymers by Interfacial and Solution Methods", Chapter VII, Paul W. Morgan, Interscience Publishers, 1965). If constant, faster acid chloride addition to the reaction mixture for higher molecular weight. Also, higher agitation speed was significantly useful, and using a Morton flask seemed to help obtain higher molecular weights.

Example 1 A. From 4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dibromophenol] (Compound I) and 100% isophthaloyl chloride Preparation of polyarylate.

In a 500 ml three-neck round bottom Morton flask equipped with a mechanical stirrer, thermometer, addition funnel, nitrogen inlet and condenser,
26.07 g of compound I, 0.4 g of tetrabutylammonium hydrogen sulfate, 10.25 g of 45.9% potassium hydroxide aqueous solution, 40 ml of distilled water, and 40 ml of methylene chloride were added. While cooling with ice water, 8.12 g of isophthaloyl chloride was added to 80 ml of methylene chloride.
The solution dissolved in was added in about 15 minutes with very fast stirring. After stirring for about 2 hours, 100 ml of methylene chloride was added and 0.5% sulfuric acid was added to acidify the mixture. The polymer solution was washed 3 times with 1000 ml of distilled water. The polymer was coagulated in methanol and dried in a vacuum oven at 80 ° C overnight. The yield was 27.2 g of polyester. The reduced viscosity was 0.42.

B. A 2.06 mil (0.0523 m) thick gas dialysis flat membrane was prepared and evaluated for the permeation of oxygen, nitrogen, carbon dioxide, methane and helium.

Oxygen P = 5.25 (× 10 ^-10 cm ³ (STP) cm / cm ² −sec cm Hg
(Barrer). The oxygen / nitrogen selectivity was 6.7.

Carbon dioxide P = 19.9 Barrer and carbon dioxide / methane selectivity at 35 psia (2.5 kg / cm ² A) using pure gas is 50
Met.

Helium P = 57 Barrer and helium / methane selectivity
It was 133.

The nitrogen P = 0.787 Barrer and the nitrogen / methane selectivity was 1.8.

Example 2 A. Preparation of polyarylates from compound I and isophthaloyl chloride / terephthaloyl chloride 80/20.

The procedure was essentially the same as in Example 1, but the amount of reagent was 2
Changed. 45.9% aqueous potassium hydroxide solution 10.734 g, isophthaloyl chloride 6.5 g, terephthaloyl chloride 1.6
Charged 25g. The polyester yield was 28 g and the reduced viscosity was 0.37. This polymer has an iso / tele ratio of 80/2
Has zero.

B. A 1.24 mil (0.0315 mm) thick gas dialysis flat membrane was prepared and evaluated for the permeation of oxygen, nitrogen carbon dioxide, methane and helium.

Oxygen P = 5.7 (Barrer). The oxygen / nitrogen selectivity was 6.4.

Carbon dioxide P = 24 Barrer with pure gas and carbon dioxide / methane selectivity was 48.

Helium P = 57 Barrer and helium / methane selectivity
It was 113.

Example 3 A.4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dibromophenol] (Compound I) and 25/75 isophthaloyl chloride /
Preparation of polyarylates from terephthaloyl chloride.

In a 500 ml three-neck round bottom Morton flask equipped with a mechanical stirrer, thermometer, addition funnel, nitrogen inlet and condenser,
Compound I52.15 g, tetrabutylammonium hydrogen sulfate 0.8 g, 45.9% potassium hydroxide solution 19.94 g, distilled water
160 ml and methylene chloride 80 ml were added. While cooling with ice water, a solution of 12.18 g of terephthaloyl chloride and 4.06 g of isophthaloyl chloride dissolved in 100 ml of methylene chloride,
It was added in about 15 minutes with very fast stirring. After stirring for about 80 minutes, 100 ml of methylene chloride was added and 0.5% sulfuric acid was added to acidify the mixture. The polymer solution was washed 3 times with 500 ml of distilled water. The polymer was coagulated in methanol and dried in a vacuum oven at 80 ° C overnight. The yield was 54.5 g of polyester. The conversion year was 0.89.

B. A gas dialysis flat membrane having a thickness of 2.7 mils (0.069 mm) was evaluated according to the procedure described in Example 1. In both gas separation processes, it was observed that there was a combination of high values from both permeation rate and selectivity.

Oxygen P = 9.0 Barrer. Oxygen / nitrogen selectivity was 6.1.

Carbon dioxide P = 42 Barrer and carbon dioxide / methane selectivity was 42 based on 35 psia (2.5 kg / cm ² A) of pure gas.

Helium P = 75 Barrer and helium / methane selectivity
It was 75.

The nitrogen P = 1.5 Barrer and the nitrogen / methane selectivity was 1.5.

The tetrabromobisphenol A polycarbonate resin of Example 1 of EPA 0242147 has the oxygen P = 0.8B in Table 1.
It showed an arrer and oxygen / nitrogen selectivity of 7.4. EPA 0244126
The tetrabromobisphenol A polyester carbonate resin of Example 4 of the publication shows an oxygen P = 1.23 Barrer and an oxygen / nitrogen selectivity of 7.2 in the table.

The data for the bisphenol polyesters of the present invention show a much better combination of permeation and separation factors for oxygen / nitrogen compared to the values reported in the two references. The polyester film of the present invention exhibited a permeability of 11.25 times higher than that of the reference polycarbonate and 7.32 times higher than that of the polyester carbonate.

Example 4 A. Preparation of polyarylates from compound I and 100% 4-bromoisophthaloyl chloride.

The synthetic procedure was essentially the same as in Example 1, but with two changes. 4-Bromoisophthaloyl chloride (22.5
54 g) was used and all amounts were halved from Example 1. The reduced viscosity was 0.29 in chloroform.

B. A 3.91 mil (0.0993 mm) thick gas dialysis flat membrane was made and evaluated for oxygen, nitrogen, carbon dioxide, methane, and helium permeation.

Oxygen P = 4.7 Barrer and oxygen / nitrogen selectivity was 6.8.

Carbon dioxide P = 1.94 Barrer and carbon dioxide / methane selectivity at 35 psia (2.5 kg / cm ² A) using pure gas is 49
Met. Mixed gas uses 50/50 gas mixture, 167ps
Carbon dioxide at ia (11.7kg / cm ² A) P = 17.2 Barrer
And a selectivity of 48.

Helium P = 51 Barrer and helium / methane selectivity
It was 130.

The nitrogen P = 0.68 Barrer and the nitrogen / methane selectivity was 1.7.

Example 5 A. Preparation of polyarylates from compound I and 100% 2-bromoterephthaloyl chloride.

The synthetic procedure is essentially the same as in Example 1. Two modifications were made, replacing the isophthaloyl chloride of Example 1 with 2-brominated terephthalic acid chloride. Only half the molar amount of Example 1 was used. Yield was 31.7g, RV was 0.51.

The B. film looked very cloudy, probably due to the high level of crystallinity, so no transmission measurements were made.

Example 6 A. Preparation of polyarylene from compound I and 100% terephthaloyl chloride.

Essentially the same procedure as described in Example 1 was adopted. The only difference was that 8.12 g of terephthaloyl chloride was used in place of the isophthaloyl chloride of Example 1. The yield was 29 g of polymer insoluble in methylene chloride and the polymer appeared to be crystalline.

Example 7 A. Preparation of polyarylates from 80/20 mixture of bisphenol compounds I and III in molar ratio and 75/25 molar ratio of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed was that described in Example 3. The polyester yield was 27.8 g and the reduced viscosity was 0.39.

B. A 2.3 mil (0.058 mm) thick gas dialysis flat membrane was evaluated according to the procedure described in Example 1. In the gas separation process, it was observed that there was a combination of high values for both permeation rate and selectivity.

Oxygen P = 9.3 Barrer. The oxygen / nitrogen selectivity was 5.8.

Helium P = 73 Barrer and helium / nitrogen selectivity 46
Met.

Example 8 A. Preparation of a polyarylate from a 70/30 molar ratio mixture of bisphenol compounds I and III and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed was that described in Example 3. The polyester yield was 24.93 g and the converted viscosity was 0.34.

B. A 4.1 mil (0.10 mm) thick gas dialysis flat membrane was evaluated according to the procedure described in Example 1. In the gas separation process, it was observed that there was a combination of high values for both permeation rate and selectivity.

Oxygen P = 11.5 Barrer. The oxygen / nitrogen selectivity was 5.6.

Helium P = 88 Barrer and helium / nitrogen selectivity is 43
Met.

Example 9 A. Preparation of a polyarylate from a 60/40 molar ratio mixture of bisphenol compounds I and IV and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed is that described in Example 3, 46% by weight
10.73 g of potassium hydroxide and 40 ml of water were used. The yield of polyester was 25.74 g and the converted viscosity was 0.57.

B. A 4.2 mil (0.11 mm) thick gas dialysis flat membrane was evaluated using the procedure described in Example 1. It was observed that in the gas separation process, there was a combination of high values for both permeation rate and selectivity.

Oxygen P = 8.83 Barrer and oxygen / nitrogen selectivity was 5.66.

Helium P = 68.5 Barrer and helium / nitrogen selectivity
It was 44.

Example 10 A. Preparation of a polyarylate from a 70/30 molar ratio mixture of bisphenol compounds I and II and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed was that described in Example 9. The yield of polyester was 27.1 g and the reduced viscosity was 0.59.

B. A 4.1 mil (0.10 mm) thick gas dialysis flat membrane was evaluated according to the procedure described in Example 1. In the gas separation process, it was observed that there was a combination of high values for both permeation rate and selectivity.

Oxygen P = 9.95 Barrer and oxygen / nitrogen selectivity was 5.82.

Helium P = 78 Barrer and helium / nitrogen selectivity 46
Met.

C. Pure gas carbon dioxide P = Barrer and carbon dioxide / methane selectivity was 46. Hybrid gas separation of CO ₂ / CH ₄ 50/50 mixture at 3 atm had selectivity 44 and did not show significant plasticization from carbon dioxide. This composition has a higher carbon dioxide permeability and better CO ₂ / CH ₄ selectivity of both combinations than reported in the art. If plasticization of these polyarylates does not occur as indicated, then these membranes are an unexpected and unpredictable advance in the CO ₂ / CH ₄ separation field.

Example 11 Preparation of a polyarylate from a 60/40 molar ratio mixture of bisphenol compounds I and II and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed was that described in Example 9. The yield of polyester was 18.4 g and the converted viscosity was 0.61. Dialysis flat membranes can be manufactured by following the procedure described in Example 1.

Example 12 A. Preparation of polyarylates from a 75/25 molar ratio mixture of bisphenol compounds I and III and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed was that described in Example 9. The yield of polyester was 26.8 g and the reduced viscosity was 0.38.

B. Gas dialysis flat membrane with a thickness of 4 mils (0.10 mm), Example 1
Evaluation was performed according to the procedure described in. In the gas separation process, it was observed that there was a combination of high values for both permeation rate and selectivity.

Oxygen P = 11.8 Barrer and oxygen / nitrogen selectivity was 5.53.

Helium P = 85.1 Barrer and helium / nitrogen selectivity
It was 40.

Example 13 Preparation of a polyarylate from a 60/40 molar ratio mixture of bisphenol compounds I and II and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed is that described in Example 9, with 4.06 each of isophthaloyl chloride and terephthaloyl chloride.
used g. The yield of polyester was 25.2 g and the converted viscosity was 0.29. Gas dialysis flat membranes can be manufactured by following the procedure described in Example 1.

Example 14 Preparation of a polyarylate from a 60/40 molar ratio mixture of bisphenol compounds I and IV and a 75/25 molar ratio mixture of terephthaloyl chloride and isophthaloyl chloride.

The procedure followed is that described in Example 1, 6.091 g isophthaloyl chloride and 2.03 terephthaloyl chloride.
used g. The yield of polyester was 25.3 g and the converted viscosity was 0.75. Gas dialysis flat membranes can be manufactured according to the procedure described in Example 1.

Comparative Run 1 A. Preparation of Polyarylate from Compound II and 100% Isophthaloyl Chloride.

A polyester was prepared from 18.9 ng of compound II and 8.12 g of isophthaloyl chloride essentially according to the procedure of Example 2 with a yield of 19.9 g. Converted viscosity is 0.4 in chloroform
Was 6.

B. Gas dialysis flat membranes having a thickness of 1.88 mils (0.0478 mm) were prepared and evaluated for oxygen and nitrogen separation.

Oxygen P = 5.64 Barrer and oxygen / nitrogen selectivity was 6.1.

Transmittance values (P in Barrer) for the polyesters of the present invention (first 9 entries) and the polyesters of comparative data from the literature as drawn by the inventors (8 latter entries) and The oxygen / nitrogen selectivity and helium / nitrogen selectivity values are summarized in Table 1.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor George Lewis Broad Carlen Drive 653, Brigiwater, NJ, USA (56) References Japanese Patent Laid-Open No. 53-66880 (JP, A) Japanese Patent Publication No. 3-500146 (JP, A)

Claims (7)

[Claims] 1. An aromatic dicarboxylic acid or derivative thereof and more than 50 mol% of tetrabromobisphenol of the following general formula: (In the formula, R'is Or a divalent cyclododecyl), which is a gas separation membrane containing a layer mainly composed of polyester or copolyester derived from the aromatic dicarboxylic acid or its derivative (1). (A) Isophthalic acid or its dichloride as a dicarboxylic acid compound and / or 4-bromoisophthalic acid or its dichloride 80
Mol% or more and (b) terephthalic acid or its dichloride and / or 2-bromoterephthalic acid or its dichloride 20 mol% or less, or (2) (a) isophthaloyl dichloride and / or Or 4-bromoisophthalic acid or its dichloride 30 mol% or less and (b)
A gas separation membrane containing terephthalic acid or its dichloride and / or 70 mol% or more of 2-bromoterephthalic acid or its dichloride. 2. An aromatic acid or derivative thereof and more than 50 mol% of said tetrabromobisphenol (I) and less than 50 mol% of a bisphenol of the following general formula: The gas separation membrane according to claim 1, which is derived by reacting with a mixture of diols (wherein R'is methyl or chlorine). 3. The combination in the case of oxygen and nitrogen exhibits a selectivity of at least 5.6 to 7.2 and a permeability of at least 4.7 to 11.8 Barrer at ambient temperature and / or the combination in the case of carbon dioxide and methane is selected at ambient temperature. A gas separation membrane according to claim 1 having a permeability of at least 30 and a permeability of at least 15 Barrer. 4. In the case of the oxygen / nitrogen separation, the polyether is 4,4 ′-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dibromophenol]. A gas separation membrane according to claim 1, comprising at least 80 mol% isophthalate and not more than 20 mol% terephthalate, based on the base membrane. 5. When the polyether is carbon dioxide / methane separation, 4,4 ′-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis [2,6-dibromophenol] A gas separation membrane according to claim 1, comprising at least 70 mol% terephthalate and not more than 30 mol% isophthalate for a membrane based on. 6. The main repeating unit of the polyether has the following structural formula: (Wherein R'is as defined in claim 1, R is hydrogen or bromine, and x is an integer having a value of at least 20). Polyester gas separation membrane. 7. An O ₂ / N ₂ or CO ₂ / CH ₄ gas mixture is brought into contact with one side of the gas separation membrane according to any one of claims 1 to 6, and both sides of the membrane are separated. Maintaining a pressure differential of 1 and removing the permeated component from the other side of the membrane.