RU2196789C2 - Perfluorinated ion-exchange copolymer- based liquid composition - Google Patents

Abstract

FIELD: ion- exchange polymer materials. SUBSTANCE: invention relates to perfluorinated copolymer containing functional sulfonic groups than can be used when manufacturing and repairing ion-exchange membranes useful in alkali chloride hydrolysis or water electrolysis, in fuel and gas separation cells, as well as for impregnating various substrates, etc. with free or alkali metal bound sulfonic acid groups having equivalent mass above 1000 and polar organic solvent or mixture of polar organic solvent with nonpolar solvent. Polymer is characterized by number-average molecular weight (1-8) x 10⁵, ratio of weigh- average molecular weight to number-average molecular weight between 1.2 and 1.4 and content of crystallization water 2-5 wt.%. EFFECT: increased strength of products. 4 cl, 2 tbl, 22 ex

Description

The invention relates to a liquid composition based on a perfluorinated ion-exchange copolymer containing functional sulfo groups of the formula —SO ₃ M, where M is a hydrogen or alkali metal ion, and a polar organic solvent or a mixture of organic solvents. Such compositions can be used in the manufacture and repair of ion-exchange membranes (IOM) used in chlor-alkali electrolysis or water electrolysis, in fuel and gas separation elements, for the impregnation of various substrates, in the manufacture of super acid catalysts for the synthesis of organic compounds, etc.

или гидролизованный сополимер ТФЭ с сульфосодержащим виниловым эфиром формулы:
CF₂=CF-O-CF₂-CF₂-SО₂F,
с эквивалентной массой (ЭМ) 400-1000. (ЭМ - масса гидролизированного сополимера в г в расчете на 1 г-экв функциональных групп).Known (Japan Patent 13333-73, NKI 25 (1) C 122.2, publ. 04/26/73) solutions including ion-exchange perfluorinated copolymer with functional groups —SO ₃ M (where M is hydrogen, monobasic amine, alkali metal atom) and polar organic solvent. As a perfluorinated ion-exchange copolymer, the solution (composition) contains a hydrolyzed copolymer of tetrafluoroethylene (TFE) with a sulfonated vinyl ether (VGE), for example, an ether of the formula

or a hydrolyzed copolymer of TFE with a sulfonated vinyl ether of the formula:
CF ₂ = CF-O-CF ₂ —CF ₂ —SO ₂ F,
with equivalent mass (EM) 400-1000. (EM is the mass of hydrolyzed copolymer in g per 1 g-equiv of functional groups).

As a polar organic solvent, the composition contains a solvent selected from the group of aliphatic alcohols with no more than 4 carbon atoms (methanol, ethanol, isopropanol, n-propanol, n-, iso- and tertiary butanol), fluoroalcohols H (CF ₂ ) ₄ CH ₂ OH, substituted amides (dimethylformamide, dimethylacetamide, etc.), cellosolve, acetone, etc.

The composition is obtained by mixing the specified copolymer with a solvent by heating to 22-170 ^o C and stirring (the molecular weight of the copolymer to be dissolved, as well as details of the process, such as duration, possibility of concentration, etc., are not given in Japanese patent 13333-73) . After mixing the components, a composition is obtained containing 0.09-30 wt. % copolymer, from which by irrigation or impregnation it is possible to obtain IOM, filters used in electrolysis processes, separator battery filters. The copolymer content in the composition substantially depends on the EM of the copolymer used. So, when using a copolymer with an EM from 400 to 860, compositions with a copolymer content of up to 30 wt.% Can be obtained, and when using a copolymer with an EM from 860 to 1000, the composition preferably contains 0.5-1 wt.% Of the copolymer.

The disadvantages of the above composition are:
1. The use in the composition of ion-exchange copolymers with low EM (not more than 1000), which give films (membranes) with low strength, especially at elevated operating temperatures, and therefore IOMs made from such compositions cannot be used for a long time in fuel cells (TE), during electrolysis of water, in the processes of chlor-alkali electrolysis. In addition, IOM from a copolymer with EM <1000, even obtained by impregnation, are not suitable for use in chlor-alkali electrolysis processes because of their low selectivity and high gas permeability.

 2. The low content of the copolymer (0.54 - 1%) in the composition in the case when a copolymer with a relatively high EM (from 860 to 1000) is used, which leads to the fact that such compositions, when applied on a substrate, give a film thickness of 5-6 microns; therefore, for the manufacture of IOM, usually used in the processes of electrolysis and FC (thickness 150-250 microns), the application of more than 25-30 layers with the mandatory removal of solvent from each layer and subsequent sintering is required. Compositions comprising a copolymer with low EM (less than 860), although it contains a larger amount of copolymer - up to 30 wt.%, Cannot be used to obtain IOM in the form of films or fibers due to extremely low strength.

Also known is a polymer composition comprising a perfluorinated polymer containing sites capable of being converted into ion-exchange groups and a solvent (USSR patent 1769760, MKI ⁵ C 08 L 27/12, publ. 15.10.92). As a perfluorinated polymer, the composition contains 0.3-13.9 wt.% Of a TFE copolymer and a monomer selected from the group consisting of:
CF ₂ = CF-O-CF ₂ -CF ₂ -SO ₂ F (I);
CF ₂ = CF — O — CF ₂ —CF ₂ —COOCH ₃ (II).

 The EM of the TFE copolymer with monomer (I) is from 850 to 1160, and the EM of the TFE copolymer with monomer (II) is 755 and 847, i.e. The EM copolymer used in the composition is in the range of 755-1160. As a solvent, the composition contains 99.7-86.2 wt. % 1,2-dibromotetrafluoroethane (DBTFE).

The specified polymer composition is obtained by mixing a perfluorinated copolymer in non-ionic form (with -SO ₂ F or -COOCH ₃ groups) with the first portion of DBTFE in a laboratory roller impact mill overnight. The remainder of the DBTFE is then added and the mixture is further stirred for 3 hours. The composition is obtained in the form of a 0.3-13.8% dispersion of a perfluorinated copolymer in DBTFE. Membranes are obtained from the composition by applying a dispersion on a sheet of aluminum foil and then sintering at 250-303 ^o C. The dispersion on the aluminum foil is applied 2-5 times to obtain the desired film thickness. The resulting film is subjected to hydrolysis with a 25% aqueous solution of sodium hydroxide at 90 ^° C for 16 hours to convert the nonion exchange starting groups of the perfluorinated copolymer to ion exchange, after which the hydrolyzed film is used as IOM in the electrolyzer to produce chlorine and alkali.

The disadvantages of the composition according to the patent of the USSR 1769760 are:
1. The inability to obtain directly IOM from the specified polymer composition, since the composition contains a copolymer with nonionic groups and an additional hydrolysis of the formed films (products) is required to transfer these groups into ion-exchange groups.

2. The need to use high temperatures (about 250-300 ^o C) when receiving from the composition of films or other products, since the polymer composition is a dispersion of the copolymer in a solvent and high temperatures are necessary for sintering the polymer.

3. The limited scope of the composition, since such a composition cannot be used to impregnate non-heat-resistant and chemically unstable materials, for example, nylon, paper, polyethylene and others, used as filters in the pharmaceutical industry or medicine, which cannot withstand high sintering temperatures as well as hydrolysis with a 25% aqueous solution of sodium hydroxide at 90 ^o C for 16 hours, which is necessary for the transfer of nonionic groups into ion exchange.

Closest to the combination of essential features of the claimed composition is a liquid composition according to USSR patent 1286108 (MKI ³ C 08 J 3/02, publ. 23.01.87), containing perfluorinated ion-exchange copolymer with functional sulfo groups of the formula -SO ₃ M, where M is an ion hydrogen or an alkali metal (Na or K) having an EM of 1050-1500, and a solvent. As a perfluorinated ion exchange copolymer, the composition contains, for example, a hydrolyzed copolymer of TFE and perfluoro (3,6-dioxa-4-methyl-7-octensulfonyl fluoride) (TFE / PSEPVE) with EM 1050-1500, and as a solvent, water or a mixture of 20 -80 wt.% Water and 80-20 wt.% Polar organic solvent (methanol, ethanol, n-butanol and others). A composition in 100 ml contains from 0.2 to 13 g of a dissolved copolymer. The molecular weight of the ion exchange copolymer is not given in USSR Patent 1286108. Such compositions are used in the manufacturing and repair of IOM used in electrolysis processes. IOM can be obtained directly from these compositions, since the composition contains a copolymer with ion-exchange groups.

The disadvantages of the composition according to the patent of the USSR 1286108 (prototype) are:
1. The limited scope of the composition, which is associated with the low strength of the products obtained from it - films, fibers, since the composition uses an ion-exchange copolymer with a relatively low EM (1050-1500), as well as, probably, with unfavorable molecular weight characteristics of the copolymer. Thus, the strength of a film from a liquid composition based on a copolymer with EM 1100 formed at 120 ^° C has a tensile strength of 17.7 MPa (see Example 3 of the description of USSR Patent 1286108), but even this strength is achieved by the additional introduction of the composition of triethyl phosphate (in an amount of 110% by weight of the polymer), which remains in the resulting copolymer film. The low strength of the obtained products - films, fibers, does not allow using them directly (without additional reinforcement) as an IOM, for example, in fuel cells, or as gas separation fibers. The use of such films and fibers as gas separation membranes is also hindered by the relatively narrow interval of the EM copolymer, since the copolymer with EM> 1500 is often required for efficient gas separation. In addition, such a composition cannot be used to obtain air humidity sensors, hydrogen sensors, for drying gases, and some other applications where a copolymer with EM> 1500 is also required.

2. The complexity of the process of obtaining the composition associated with the need to mix the components at high temperatures (170-250 ^o C) under pressure, prolonged heating at these temperatures (3-18 hours) and subsequent distillation of part of the solvent. Probably, such a difficulty in obtaining the composition is due to the fact that the composition contains copolymers with a high degree of crystallinity. It is known that usually copolymers of TFE with perfluorosulfonylated vinyl ether (TFE / PSEPVE), for example, Nafion brand Du Font, have a high degree of crystallinity (Perfluorinated Ionomer Membranes, ACS Symposium, USA, Washington, 1982). So, the copolymer with EM 1100 has a crystallinity of 12%, with EM 1200 - 19%, and with EM 1400 - 20%.

 The technical result, which is achieved by the claimed liquid composition, is to expand the fields of application of products (films, fibers, tubes, etc.) obtained from the composition, as well as to simplify the process of its preparation.

The specified technical result is achieved due to the fact that in a liquid composition containing a perfluorinated ion exchange copolymer with functional sulfo groups of the formula —SO ₃ M, where M is a hydrogen or alkali metal ion having an EM of more than 1000, and a polar organic solvent or a mixture of polar organic solvent and non-polar solvent, as a perfluorinated ion exchange copolymer, the composition contains a hydrolyzed copolymer of tetrafluoroethylene with perfluorosulfonate vinyl ether or hydrolysis a copolymer of tetrafluoroethylene with perfluorosulfonate vinyl ether and a third modifying comonomer selected from the group consisting of perfluoro-2-methylene-4-methyl-1,3-dioxalane and perfluoroalkyl vinyl ether containing 1-3 carbon atoms in the alkyl, each of which has a number average molecular weight (1-8) • 10 ⁵ , the ratio of the mass-average molecular weight to the number average molecular weight (M _w / M _n ), equal to 1.2 ÷ 1.4, the content of crystallization water 2-5 wt. %, crystallinity 7-20% and density 2.070-2.097 g / cm ³ , with the following components, wt.%:
Perfluorinated Ion Exchange Copolymer - 1-37
Polar organic solvent or its mixture with a non-polar solvent in the ratio (1-15): 1, respectively - 63-99
The inventive liquid composition contains the specified copolymer having an equivalent weight of 1030-3000. As a polar organic solvent, the composition contains one or more solvents selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, cyclohexanone, acetone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, morpholine, ux methyl glycol, ethyl acetate, methyl acetate, diethyl ether. As a non-polar solvent, the composition contains one or more non-polar organic solvents selected from the group consisting of 1,1,2-trifluoro-1,2-dichloroethane, 1,1-difluoro-1,2-dichloroethane, 1,1,2- trifluorotrichloroethane, 1,1,1-trichlorobromoethane, 1,1-difluoro-1,2,2-trichloroethane, pentane, hexane, heptane, benzene, toluene, cyclohexane, carbon tetrachloride, dioxane.

As mentioned above, in known sources of information, the molecular weight of the copolymer to be dissolved and the ratio M _w / M _n are not usually given. The authors of the present invention conducted studies that showed that the number average molecular weight, as well as the ratio M _w / M _{n of the} ion-exchange perfluorinated copolymer with functional sulfo groups —SO ₃ M, where M is hydrogen or an alkali metal, have a significant effect on its solubility in polar organic solvent or in a mixture of a polar solvent (s) with a non-polar solvent (s). It was found that when the number average molecular weight (M _n ) of the copolymer to be dissolved is (1-8) • 10 ⁵ , and when the ratio M _w / M _n in the range from 1.2 to 1.4, the necessary diffusion of the organic solvent is ensured ( solvents) in the macromolecule of the copolymer, which facilitates the dissolution of the copolymer and its transition into a stable solution.

An increase in M _{n of the} soluble copolymer of more than 8 • 10 ⁵ makes it impossible to obtain a high-quality stable composition (solution) due to the tendency to precipitate a high molecular weight polymer from the composition (solution), and a decrease in M _n below 1 • 10 ⁵ leads to a deterioration in the physico-mechanical properties of the membranes fibers and other products obtained from a liquid composition (solution) (see our control examples 11 and 16).

The decrease in the ratio M _w / M _n below 1.2 leads to the fact that for the preparation of the composition (solution) requires more stringent dissolution conditions of the copolymer (higher temperature and longer process time), and in some cases, for example, if the copolymer has EM > 1200-1500, even in more severe conditions, it is impossible to obtain a stable composition (see our control example 12).

 An increase in the Mw / Mn ratio of more than 1.4 is impractical, since although the process of preparing the composition is facilitated, the physical and mechanical properties of the products obtained from the composition are deteriorated (strength, gas permeability, etc.) (see our control example 15).

The authors also found that if the soluble ion-exchange copolymer contains 2-5 wt. % of crystallization water and has M _n and the ratio M _w / M _n in the above ranges, then perfluorinated ion-exchange copolymers with sulfo groups having practically any degree of crystallinity can be dissolved (usually, when synthesizing a perfluorosulfosopolymer, the degree of crystallinity is in the range of 2-26%). An increase in the content of crystallization water in the copolymer of more than 5 wt.% And a decrease in crystallization water below 2 wt.% Leads to the fact that the copolymer does not dissolve (see our control examples 13-14).

The use of ion-exchange perfluorinated copolymer with functional sulfo groups -SO ₃ M, where M is a hydrogen or alkali metal ion having Mn (1-8) • 10 ⁵ , the ratio M _w / M _n 1.2-1.4 and the content of crystallization water 2 -5 wt.%, Makes it possible relatively easily without using high temperatures for no more than 1.5-2 hours to obtain stable compositions (solutions) of copolymers with EM 1030-3000 concentration of 1-37%. No solvent stripping is required. The resulting solutions can be stored for a long time (at least 6 months) without changing the viscosity of the solution and the visible precipitation of the copolymer.

The number average molecular weight and the ratio M _w / M _{n of the} sulfo group copolymer used in the claimed composition are governed by the synthesis conditions of the initial copolymer in non-ionic form or by introducing a third comonomer into the copolymer. The required content of crystallization water in the copolymer is achieved both by controlling the synthesis conditions of the initial copolymer, and by the conditions for the transfer of the nonionic groups of the original copolymer into ion-exchange groups (by hydrolysis conditions), as well as by drying conditions.

где m=84,7 мол.%;
n=15,3 мол.%;
со степенью кристалличности 12% и плотностью 2,070 г/см³.In the following embodiments, copolymers of the following structural formulas synthesized by the inventors were used:
SPL-1 with EM 1030

where m = 84.7 mol.%;
n = 15.3 mol%;
with a degree of crystallinity of 12% and a density of 2.070 g / cm ³ .

где m=96,21 мол.%;
n=3,79 мол.%;
со степенью кристалличности 20% и плотностью 2,097 г/см³.SPL-2 with EM 3000

where m = 96.21 mol.%;
n = 3.79 mol%;
with a degree of crystallinity of 20% and a density of 2.097 g / cm ³ .

где m=84,5 мол.%;
n=13,1 мол.%;
k=2,4 мол.%;
со степенью кристалличности 9% и плотностью 2,078 г/см³.SPL-3 with EM 1100

where m = 84.5 mol.%;
n = 13.1 mol%;
k = 2.4 mol%;
with a crystallinity of 9% and a density of 2.078 g / cm ³ .

где m=78,9 мол.%;
n=15,8 мол.%;
k=5,3 мол.%;
со степенью кристалличности 18% и плотностью 2,071 г/см³.SPL-4 with EM 1070

where m = 78.9 mol%;
n = 15.8 mol%;
k = 5.3 mol%;
with a degree of crystallinity of 18% and a density of 2.071 g / cm ³ .

где m=92 мол.%;
n=8 мол.%;
со степенью кристалличности 16% и плотностью 2,087 г/см³.SPL-5 with EM 1600

where m = 92 mol.%;
n = 8 mol%;
with a degree of crystallinity of 16% and a density of 2.087 g / cm ³ .

где m=78,5 мол.%;
n=13,1 мол.%;
k=8,4 мол.%;
со степенью кристалличности 7% и плотностью 2,083 г/см³.SPL-6 with EM 1200

where m = 78.5 mol.%;
n = 13.1 mol%;
k = 8.4 mol%;
with a crystallinity of 7% and a density of 2.083 g / cm ³ .

где m=92,6 мол.%;
n=7,4 мол.%;
со степенью кристалличности 17,5% и плотностью 2,088 г/см³.SPL-7 with EM 1700

where m = 92.6 mol%;
n = 7.4 mol%;
with a degree of crystallinity of 17.5% and a density of 2.088 g / cm ³ .

The inventive liquid composition is obtained by dissolving the ion-exchange perfluorinated copolymer powder in one or more polar organic solvents or in a mixture of one or more polar solvents with a non-polar organic solvent (s) with stirring. The dissolution temperature is in the range of 20-90 ^o C and is determined by the composition and EM of the copolymer, as well as the boiling point of the solvents used. Products from the composition were obtained by irrigation or impregnation with a stepwise rise in temperature from room temperature to 40-80 ^o C, depending on the type of solvent. Gas separation hollow fiber was obtained by the method of "wet" molding.

The properties of the ion-exchange perfluorinated copolymer and the solutions obtained from it were determined as follows:
1. The composition of the perfluorinated copolymer was determined by IR spectroscopy on a spectrometer company Perkin-Elmer, model 1760.

 2. EM copolymer was determined according to GOST 17552-72.

3. The number-average and mass-average molecular weights were determined by thin-layer or liquid chromatography of a 1-5% copolymer solution in isopropyl alcohol. The ratio M _w / M _{n was} determined by calculation.

 4. The degree of crystallinity was determined by X-ray diffraction using a small-angle scattering chamber KRM-1.

 5. The density of fluoropolymers was determined according to GOST 15139-69.

 6. The viscosity of the composition was determined according to GOST 9070-75E.

 7. The strength of the films obtained from the copolymer was determined according to GOST 14236-81.

 8. The content of crystallization water was determined by IR spectroscopy on a spectrometer company Perkin-Elmer, model 1760.

 The following examples illustrate the present invention.

 Example 1

To obtain a liquid composition, the perfluorinated ion-exchange TFE copolymer with perfluorosulfonate vinyl ether - SPL-2, with a degree of crystallinity of 20%, EM 3000, with ion-exchange groups in the form of-SO ₃ H, copolymer density of 2.097 g / cm ³ , M _n = 8 • is used. 10 ⁵ , the ratio M _w / M _n = 1.2 and the content of crystallization water of 2 wt.%.

A 500 ml round-bottom glass flask equipped with a propeller stirrer, a thermometer and a reflux condenser is charged with 4 g of the indicated SPL-2 copolymer in the form of a powder with a particle size of 500-600 μm, 196 g of a polar organic solvent - isopropyl alcohol (isopropanol), includes a stirrer , the contents are heated to a temperature of 80 ^o C and maintained with stirring at the indicated temperature for 2 hours. Then the flask is cooled and the resulting liquid composition is filtered through a nylon filter. The composition is a solution with a copolymer content of 2 wt.% (2 wt.% Copolymer SPL-2 and 98 wt.% Isopropanol).

 Examples 2-10; 11-16 (control).

The liquid composition is obtained analogously to example 1, but vary the composition and conditions for obtaining the composition. From the compositions of Examples 1-16, by pouring onto a glass plate followed by drying at temperatures of 20-90 ^° C, films with a thickness of 100 μm were obtained and their tensile strength at break was determined according to GOST 14236-81.

 The composition of the compositions obtained in examples 1-10 and 11-16 (control), the dissolution conditions of the copolymer (preparation conditions of the compositions), as well as the properties of the compositions and films from them are shown in tables 1 and 2, respectively.

 Example 17

 The composition obtained in example 1 and containing 2 wt.% Copolymer SPL-2 with EM 3000 and 98 wt.% Isopropanol, is used as a binder to obtain a membrane-electrode block (OIE).

In a glass container, 0.9 g of electrocatalyst - platinum black (particle diameter - 0.09 μm) is mixed with 0.03 g of an electrically conductive inactive material - carbon black with a particle size of 0.01 μm. Then to the resulting mixture add 3.5 g of the composition according to example 1, namely a 2% solution of the copolymer SPL-2 in isopropanol. The resulting viscous mass of electrode material is applied to one of the air-dry surfaces of the IOM, which is a film 200 microns thick from a copolymer similar in composition to SPL-2, but with an EM of 1200 and a degree of crystallinity of 12%, by spreading with a layer of such a thickness that after drying the layer of electrode material had a thickness of 6 μm. Then, the obtained membrane-electrode block is placed in a thermostat and processed at the next stepwise temperature increase: it is maintained at 20-22 ^o С for 10 min, at 60 ^o С - 40 min, at 80 ^o С - 20 min. After this, the IOM is removed from the thermostat, cooled to room temperature and the same electrode material is applied on its other surface in the same way, then it is again placed in the thermostat and heat treated in the manner described above. The fabricated OIE is tested in a fuel cell as follows. A carbon cloth impregnated with polytetrafluoroethylene dispersion (TU 6-05-1246-81) is placed on both surfaces of the electrode layers of the obtained OIE and compressed. Then, carbon collectors of current are applied to both surfaces of the OIE and the assembly is installed in the fuel cell. OIE studies are carried out at 80 ^o With the flow of gases into the fuel cell: hydrogen - into the anode chamber at a pressure of 1 atm, and oxygen - into the cathode chamber at a pressure of 1.2 atm. The following characteristics are obtained:
the voltage on the element is 0.80-0.81 V;
current density - 500 mA / cm ² .

 The fuel cell worked stably for 3,000 hours, after which the process was stopped and the OIE was removed from the cell. Visual inspection of the OIE did not observe any changes.

 Example 18

 The composition obtained in example 2 and containing 12 wt.% Copolymer SPL-1 with EM 1030 and 88 wt.% Methyl ethyl ketone, is used to obtain a super-acid catalyst for the synthesis of 4-methyl-2-tert-butylphenol.

The polyethylene granules are placed in a Buchner funnel and attached to a Bunsen flask. Then this flask is evacuated, and the liquid composition is gradually poured into the funnel in an amount sufficient to ensure that all the granules are coated with it and, after removal of the solvent, have a coating of 5-10 μm thickness. Then the vacuum is turned off and the granules are dried at 22 ^{° C.} for 20 minutes and at 40 ^{° C.} for 20 minutes. After removing the solvent, granules coated with a layer of SPL-1, which are a super acid catalyst, are used in the transalkylation of 4-methylphenol with 4-methyl-2,6-ditretbutylphenol. The yield of 4-methyl-2-tert-butylphenol was 83%.

 Example 19

 The composition obtained in example 3 and containing 8 wt.% Copolymer SPL-4 with EM 1070 and 92 wt.% Acetone, is used to obtain a gas separation membrane in the form of a film.

A membrane in the form of a film is obtained by pouring on the glass of the specified composition a layer of such a thickness that, after removal of the solvent, a film with a thickness of 40 μm is formed. The glass with the composition poured onto it is placed in a thermostat and the solvent is evaporated with a gradual increase in temperature from 22 ^° C to 40 ^° C for 40 minutes (at 22 ^° C for 10 minutes, at 40 ^° C for 30 minutes). The film is removed from the glass and used as a gas separation membrane. A gaseous feed mixture of hydrogen fluoride and 1,1,2-trichlorotrifluoroethane (80 vol.% Hydrogen fluoride and 20 vol.% 1,1,2-trifluorotrichloroethane) is fed to a high pressure chamber. The differential pressure of hydrogen fluoride on the membrane is 50 kPa. Based on the analysis of the composition and quantity of the gas mixture in the receiving chamber, the selectivity coefficient was 1 • 10 ³ in favor of hydrogen fluoride with an element productivity of 0.251 m ³ / m ² • hour of the gas mixture.

 Example 20

 The composition obtained in example 9 and containing 7 wt.% Copolymer SPL-6 with EM 1200 and 93 wt.% A mixture of isopropanol and benzene (in a mass ratio of 10: 1) is used to obtain an ion-exchange membrane in the form of a film.

A membrane in the form of a film is obtained by pouring on the glass of the specified composition a layer of such a thickness that, after removal of the solvent, a film with a thickness of 200 μm is formed. The glass with the composition poured onto it is placed in a thermostat and the solvent is evaporated with a gradual increase in temperature with exposure at 22 ^° C for 10 minutes and at 75 ^° C for 40 minutes. After solvent removal, the membrane (film) had a thickness of 200 μm and a tensile strength of 3.18 • 10 ⁷ Pa. The resulting film was used as a membrane in the manufacture of OIE for the electrolysis of water.

To obtain the electrode material in a glass container, 0.92 g of a catalyst - platinum black (particle size 0.06 μm) is mixed with 2.2 g of a 1.8% solution of a copolymer SPL-5 with EM 1600 in isopropanol. The resulting viscous mass is applied to one of the surfaces of the above-mentioned IOM in the form of an air-dry film with a diameter of 100 mm by watering a mixture of such a thickness that, after removal of the solvent, the layer of electrode material has a thickness of 10 μm. Then the film is placed in a thermostat and heat treated with a stepwise rise in temperature: holding at 40 ^o C for 15 minutes, at 70 ^o C for 40 minutes After that, the OIE is removed from the thermostat, cooled to room temperature, and the same electrode material is applied to its other surface in the same way, placed in a thermostat and heat treated in the manner described above. The obtained OIE is tested during electrolysis of water. A current collector made of porous titanium with down conductors is pressed onto the OIE on both sides, the assembly obtained is sealed with a plate coupler, immersed in a vessel with distilled water, and an electric current of 0.5 A / cm ^{2 is} supplied at 90 ^° C for 1 hour. Then the assembly is installed in the cell for electrolysis of deionized water. The voltage on the block was 1.68 V at a current density of 1 A / cm ² and a temperature of 100 ^o C.

 Example 21

 The composition obtained in example 10 and containing 6 wt.% Copolymer SPL-7 with EM 1700 and 94 wt.% A mixture of isobutanol and heptane (in a mass ratio of 2: 1), is used to obtain a film for the manufacture of an air humidity sensor.

The film is obtained by pouring the composition onto glass with a layer of such a thickness that a film 140 μm thick and 50 • 50 mm in size is formed on the glass surface. The glass with the composition applied is placed in a thermostat and the solvent is evaporated by gradually raising the temperature with exposure at 22 ^° C for 10 minutes, 70 ^° C for 20 minutes and 80 ^° C for 20 minutes. After solvent removal, the membrane (film) had a thickness of 140 μm and a tensile strength of 3.2 • 10 Pa. After that, the glass with the SPL-7 film formed on it is used as a sensitive air humidity sensor, operating on the principle of changes in electrical resistance when the moisture content of the film changes. A device with the specified humidity sensor responds to changes in air humidity within 20-100%.

 Example 22

 The composition obtained in example 6 and containing 10 wt.% Copolymer SPL-5 with EM 1600 and 90 wt.% A mixture of ethanol and dimethylformamide in a mass ratio of 1: 1, is used to obtain a gas separation hollow fiber.

 Hollow fiber is obtained in a laboratory setup by the "wet" method in a precipitation bath containing 80 wt.% Water and 20 wt.% Ethanol. The inner diameter of the fiber is 80 microns, the wall thickness is 40 microns.

 The obtained hollow fiber was used in a gas separation device for separating ammonia from a mixture of ammonia and hydrogen.

The gas mixture, consisting of 50 vol.% Ammonia and 50 vol.% Hydrogen, is fed into the hollow fiber, pre-moistened with water vapor, at a pressure of 100 kPa and at a temperature of 22 ^o C. Based on the analysis of the composition of the gas mixture from the outside of the fiber, the coefficients are calculated the permeability of the constituent gases, which for ammonia and hydrogen are 3.82 • 10 ^-11 and 1.99 • 10 ^-15 mol • m / m ² • s • Pa, respectively, and a selectivity of 1.92 • 10 ⁴ in favor of ammonia. After purification, the mixture contains ammonia 99.8 vol.% And hydrogen 0.2 vol.%.

 As can be seen from the data in tables 1 and 2, the claimed composition in comparison with the known composition of the prototype contains perfluorinated ion-exchange copolymer with a wider range of equivalent masses. So, the claimed composition contains an ion-exchange copolymer with EM 1030-3000, while the composition of the prototype contains a copolymer with EM 1050-1500, i.e. 1500 more. Moreover, the claimed composition is a solution, and not dispersion, in contrast to the composition of the prototype. This range of equivalent masses of the copolymer in the inventive composition (solution) can significantly expand the field of practical application of the composition. From the claimed composition directly without any additives or reinforcing materials it is possible to obtain durable products - films, fibers and other products that can be used as membranes, for example, in the electrolysis of water (see example 20), in fuel cells (see example 17), in gas separation elements (see examples 19 and 22), air humidity sensors (see example 21). Preferably, compositions containing a copolymer with an EM greater than 1500 can be used to produce gas separation membranes in the form of asymmetric fibers, films, tubes, etc. Such membrane materials can be used, for example, to separate carbon dioxide from carbon monoxide, hydrogen fluoride from hydrogen, hydrogen fluoride from chladones, methylamine from dimethylamine and trimethylamine, 2-methyl-1-butene from pentane, etc. Compositions containing a copolymer with EM greater than 1500 can also be used as a binder in the manufacture of the OIE (see example 17), when obtaining filters for the separation of proteins, etc.

Since the claimed composition is a copolymer solution and therefore is molded into products (films, fibers, tubes, etc.) at relatively low temperatures (20-90 ^o C), it can be used to impregnate non-heat-resistant and chemically unstable materials, such as capron , polyvinyl chloride, polyethylene, paper, etc. upon receipt of superacid catalysts (see example 18), filters for separating proteins, etc. From the composition of the prototype it is practically impossible to obtain membranes that effectively separate acid gases, amines, hydrocarbon ode, it can not be used to impregnate chemically and thermally unstable materials due to the high temperature of the formation of products (more than 120 ^o C). In addition, due to the low strength of the films obtained from the compositions of the prototype films, it cannot be used in the manufacture of membranes intended for long-term operation in electrochemical devices (fuel cells, water electrolysis, chlor-alkali electrolysis, etc.) and in gas separation devices without additional hardening .

Since the claimed composition uses an ion-exchange copolymer with optimal (from the point of view of obtaining solutions) molecular weight characteristics, the process of obtaining the claimed composition (solution) is simpler, since the dissolution of the copolymer is carried out in comparison with the prototype under milder conditions: at a temperature of 20- 90 ^o C and atmospheric pressure, instead of 170-250 ^o C and autogenous pressure according to the prototype. In addition, the duration of the process of obtaining the composition compared with the process of the prototype is reduced by 2-9 times (from 3-18 hours to 1.5-2 hours), while the concentration of the composition is not required (there is no need to drive away part of the solvent).

Claims (3)

1. A liquid composition containing a perfluorinated ion-exchange copolymer with functional sulfo groups of the formula SO ₃ M, where M is a hydrogen or alkali metal ion having an equivalent mass of more than 1000, and a polar organic solvent or a mixture of a polar organic solvent and a non-polar solvent, characterized in that as a perfluorinated ion-exchange copolymer, the composition contains a hydrolyzed tetrafluoroethylene copolymer with perfluorosulfonate vinyl ether or a hydrolyzed tetraf copolymer orthylene with perfluorosulfonate vinyl ether and a third modifying comonomer selected from the group consisting of perfluoro-2-methylene-4-methyl-1,3-dioxalane and perfluoroalkyl vinyl ether containing 1-3 carbon atoms in the alkyl, each of which has a number average molecular weight (1-8) • 10 ⁵ , the ratio of the mass-average molecular weight to the number-average molecular weight equal to 1.2-1.4, the content of crystallization water 2-5 wt. %, crystallinity 7-20% and density 2.0 70-2.097 g / cm ³ , with the following content of components, wt. %:
Perfluorinated ion-exchange copolymer - 1 - 37
Polar organic solvent or its mixture with a non-polar solvent in the ratio (1-15): 1, respectively - 63 - 99
2. The composition according to p. 1, characterized in that it contains the specified copolymer having an equivalent weight of 1030-3000.  3. The liquid composition according to paragraphs. 1 and 2, characterized in that as a polar organic solvent it contains one or more solvents selected from the group comprising methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, cyclohexanone, dimethylformamide, dimethylacetamide , dimethyl sulfoxide, morpholine, acetic acid, methyl glycol, ethyl acetate, methyl acetate, diethyl ether.  4. The liquid composition according to paragraphs. 1-3, characterized in that as a non-polar solvent it contains one or more organic solvents selected from the group consisting of 1,1,2-trifluoro-1,2-dichloroethane, 1,1-difluoro-1,2-dichloroethane 1,1,2-trifluorotrichloroethane, 1,1,1-trichlorobromoethane, 1,1-difluoro-1,2,2-trichloroethane, pentane, hexane, heptane, benzene, toluene, cyclohexane, carbon tetrachloride, dioxane.

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