RU2522617C2 - Composite nanomodified perfluorosulphocationite membrane and method of obtaining thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: membrane is made of a tetrafluoroethylene copolymer with functional perfluorinated comonomers of the general structural formula:

where R:

(D),

(E),

(K), M-H, Li, K, Na; a=24.75-18.38 mol.%; b=78.62-81.12 mol.%; c=5.0-0.5 mol.%; and is from 10 mcm and higher thick, density is 1.93-2.10 g/cm³, mechanical strength is 16-22 MPa and a coefficient of gas permeability by hydrogen (K) is 1-3.7×10^-16 m³m m^-2Pa^-1s^-1 at 20-90°C. A method of obtaining consists in combination of a porous polytetrafluoroethylene film with a perfluorosulphocationite polymer in a medium of an organic or a water-organic solvent in the presence of a modifier. The modifier is represented by hydrocarbon polymers, fluoropolymers, perfluoropolymers or their mixtures, inorganic compounds or their mixtures.

EFFECT: high drops of pressure, high current density and efficiency of an electrolysis cell exploitation.

13 cl, 3 tbl, 28 ex

Description

The present invention relates to new composite nanomodified membranes, chemical compounds, namely to a nanomodified membrane based on a tetrafluoroethylene copolymer with functional perfluorinated comonomers of the general structural formula:

where R:

M-H, Li, K, Na;

a = 24.75-18.38 mol.%;

b = 78.62-81.12 mol.%;

c = 5.0-0.5 mol%;

characterized by a thickness of 10 μm or more, a density of 1.93-2.10 g / cm ³ , a mechanical strength of 16-22 MPa and a gas permeability coefficient of hydrogen (K) of 1-3.7 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° C.

The present invention also relates to organic chemistry, and in particular to a method for producing composite nanomodified perfluorosulfocationionite membranes based on the above copolymer of tetrafluoroethylene with functional perfluorinated comonomers, which can be effectively used to manufacture membrane electrode blocks (OIEs) used in various types of electrochemical devices, including in electrolyzers of low and high pressure water, portable electronic devices, etc.

The use of composite thin nanomodified membranes provides high pressure drops, a higher current density, as well as greater efficiency in the operation of the electrolysis cell.

Known (US patent No. 6059943 C258, publ. 09/05/2000) cation-conducting composite membrane consisting of an inorganic ion-conducting material and a polymer phase, which may be an ionic conductor. A polymer matrix filled with particles of an inorganic, ion-conducting material forms a connected network that penetrates the membrane from one surface to another.

The polymer matrix is preferably synthetic organic polymers having a melting point above 300 ° C, such as polymers selected from fully halogenated polymers and mixtures thereof. Preferred synthetic organic polymers are selected from polytetrafluoroethylene, perfluorosulfonic acid, perfluoroalkoxy derivatives of polytetrafluoroethylene, polysulfone, polymethylmethacrylate, silicone rubber, sulfonated copolymers of butadiene styrene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylchloride and copolymers.

Perfluorosulfonic acid is a DuPont copolymer and has the general structural formula:

and an equivalent mass (EM) of the copolymer of 1100.

The inorganic proton-conducting material may be particles of hydrated metal oxides, preferably molybdenum, tungsten, zirconium and mixtures thereof, and most preferably, inorganic particles are selected from heteropolytungstates, heteropolymolybdates, zirconium phosphates and mixtures thereof. The disadvantages of composite membranes are:

1. Not enough high gas density of the membranes. The measurement results showed that the hydrogen permeability coefficient (K) is 8-14 × 10 ^-16 m ³ m ^-2 m ^-1 s ^-1 Pa at a temperature of 20-90 ° C (see. Example 19 in Table 2, 3 ), which is associated with the increased porosity of such membranes due to poor adhesion of the inorganic material and the porous polymer matrix of polytetrafluoroethylene.

2. Insufficiently low (EM) perfluorosulfopolymer, namely 1100, which degrades the electrochemical characteristics of the membranes and limits the scope of its use in electrochemical devices.

3. Insufficient equilibrium moisture absorption and, as a consequence, low specific conductivity of the membranes.

A membrane based on a polymer matrix of porous polytetrafluoroethylene according to US patent No. 6059943 receive:

- impregnation of an inorganic proton-conducting material into the pores of a porous polymer matrix (PTFE, brand GORE TECH),

- by impregnating a precursor of an inorganic proton-conducting material into the pores of the porous matrix ((PTFE, brand GORE TECH) and then converting the material by subsequent hydrolysis to the desired proton-conducting oxide,

- precipitation of a mixture of ion-conducting oxide and a polymer binder from an aqueous solution, subsequent drying of the precipitate and the formation of the membrane,

- the conversion of the proton conductive metal oxide precursor to oxide in an aqueous solution containing an emulsion or suspension, while simultaneously precipitating the polymer with the oxide and forming a membrane,

- using a porous polymer filter as a polymer phase and filling the pores in the filter with an oxide proton conductor, filtering an oxide suspension through it, for example, vacuum filtering an amorphous zirconium phosphate gel into a porous polytetrafluoroethylene filter, followed by subsequent crystallization of zirconium L-phosphate in phosphoric acid,

- filling the pores of the porous polymer membrane with a concentrated precursor solution, preferably oxide, while preserving the precursor solution on one side and depositing the oxide phase in the filter pores on the other side, with a reaction that diffuses the oxide into the membrane, for example, by adding an acidic metal salt of this oxide, raising pH value with alkali solution.

The disadvantages of the described methods are:

1. The difficulty of filling a porous polymer substrate with the methods described above from a suspension with an inhomogeneous particle size of an inorganic conductor compound.

2. The preparation of composite membranes by the method of deposition of a mixture of proton-conducting oxide of a polymer matrix and their subsequent formation by pressing occurs at high temperatures, which leads to partial destruction of the ion-exchange polymer and the deterioration of its properties.

3. The inability to obtain thin and superthin membranes due to the heterogeneity of the particle size of the conductor.

Also known (RF patent No. 2426750, published on 08.20.2011.) Is a gas-tight modified membrane consisting of a copolymer of tetrafluoroethylene with perfluorosulfonate vinyl ether and a third modifying comonomer selected from the group: perfluoro-2-methylene-4-methyl-1,3- dioxalane and perfluoroalkyl vinyl ether containing 1 or 3 carbon atoms in the alkyl of the general structural formula:

where R:

M-H, Li, K, Na;

a = 24.7-15.7 mol%;

b = 74.3-83.8 mol%;

c = 5.0-0.5 mol%;

having an equivalent mass of copolymer comprising 900-1050, and a polymer or inorganic modifier.

Sulfonated polysulfone, polyvinyl alcohol, polyvinylidene fluoride, vinylidene fluoride copolymers, sulfonated polymers and vinylidene fluoride copolymers are used as a polymer modifier.

As an inorganic modifier, compounds of titanium, tin, zirconium, germanium, silicon, or mixtures thereof, selected from the group of oxides, phosphates, hydrophosphates, as well as tetraethoxysilane, are used.

The content of the polymer or inorganic modifier located in the volume or on the surface of the membrane is 2-30 wt.% Of the total weight of the membrane. The thickness of the membrane can be 25-150 microns.

The disadvantages of the gas-tight modified membrane according to the patent of the Russian Federation No. 2426750 are:

1. The insufficiently high surface proton conductivity due to a decrease in the specific surface ion-exchange capacity, which leads to a deterioration of the contact of the membrane surface with the catalytic mixture and, as a result, to a deterioration in the electrochemical properties of the OIE

2. The insufficiently high mechanical strength of the membranes in harsh conditions, at high pressure and temperature drops, which is associated with the specific mobility of the polymer chains of perfluorosulfopolymer.

3. Inadequate stability of linear dimensions when changing temperature and pressure due to fluctuations in the water content in the membrane, which affects the operation of the transporting nodes.

The membrane according to the patent of the Russian Federation No. 2426750 receive:

- contacting perfluorosulfonate membrane with a liquid composition,

- evaporation of a liquid medium (drying),

- the formation of modifier particles.

A membrane made from a copolymer of tetrafluoroethylene with a perfluorosulfonate vinyl ether and a third modifying comonomer selected from the group consisting of perfluoro-2-methylene-4-methyl-1,3-dioxalan or perfluoroalkyl vinyl ether containing 3 in alkyl is used as a perfluorosulfocationionite membrane. carbon atom having an equivalent mass of 900-1050.

As a liquid composition, a liquid composition is used comprising an ion-exchange perfluorosulfopolymer, a modifier and a solvent in an aqueous, organic or aqueous-organic medium, and hydrocarbon polymers, fluoropolymers, perfluorinated polymers or mixtures thereof, inorganic compounds or mixtures thereof are used as a modifier.

As a perfluorinated ion-exchange copolymer, a copolymer with functional sulfo groups of the formula —SO ₃ M is used, where M is a hydrogen, ammonium or alkali metal ion, similar in composition to the membrane polymer, having an equivalent weight of 800–900, soluble in a solvent selected from the group including: water, a polar organic solvent, a mixture of polar organic solvents, a mixture of polar and non-polar organic solvents, or a mixture thereof with water.

As the modifier, hydrocarbon polymers, fluoropolymers, perfluorinated polymers or mixtures thereof, inorganic compounds or mixtures thereof are used.

As the modifying polymer, the liquid composition comprises polyvinyl alcohol, sulfonated polysulfone, polyvinylidene fluoride, polyvinylidene fluoride copolymers, sulfonated polymers and polyvinylidene fluoride copolymers.

As an inorganic compound, the liquid composition contains titanium, tin, zirconium, germanium, silicon compounds or mixtures thereof selected from the group: chlorides, oxychlorides, oxides, hydroxides, phosphates, hydrogen phosphates, alcoholates.

As a modifying compound, the liquid composition contains tetraethoxysilane.

The process of contacting with the liquid composition is carried out at a temperature of 18-80 ° C for 2-8 hours

The process of forming a modifier in a perfluorosulfocationite membrane is carried out at a temperature of 18-110 ° C.

The disadvantages of the described methods are:

1. The difficulty of obtaining thin and superthin membranes by the methods described above with high mechanical strength in the wet state at high temperatures and pressure drops.

2. The difficulty of manufacturing membranes that are resistant to diffusion and gas leakage during operation in electrolyzers of water with a high pressure drop due to the instability of the linear dimensions.

3. The inability to obtain membranes with sufficiently high performance characteristics for electrolyzers of low and high pressure water due to the fact that the thickness of the membrane is 150-160 microns. The voltage on the cell reaches 1.61-1.65 V.

4. The impossibility of obtaining thin and superthin defect-free membranes for water electrolysis by the methods described above because of diffusion factors, since the modification uses the process of impregnation of a liquid dispersion of finished perfluorosulfocathionite membranes with a high density, and the dispersion contains modifier particles with insufficient particle size uniformity.

The closest set of essential features to the claimed composite nanomodified membrane is a membrane reinforced with polytetrafluoroethylene, patent WO 0227070, publ. 04.04.2002 - a prototype.

The reinforced membrane consists of proton-conducting and porous polymeric materials and is used in water electrolysis cells.

Ion exchange materials used as proton conducting materials include, but are not limited to, hydrocarbon-containing ion-exchanging materials and fluorocarbon ion-exchanging materials. Hydrocarbon-containing ion-exchange materials may also be used, including phenolic resins or sulfonic acids, condensation materials such as phenol-formaldehyde resins, polystyrene, styrene-divinylbenzene copolymers, styrene-butadiene copolymers, styrene-divinylbenzene copolymers and vinyl chloride copolymers, etc., sulfonated with or with anion exchange properties as a result of chloromethylation and subsequent conversion to the corresponding quaternary amines.

Fluorocarbon ion-exchange resins may include copolymers of tetrafluoroethylene with perfluoroethoxyvinyl sulfonic ether or tetrafluoroethylene with perfluorohydroxylated vinyl ether. Due to their higher oxidation and / or acid resistance, fluorinated resins containing sulfonic, carboxylic and / or phosphoric acid groups are more preferred. Fluorocarbon materials typically have excellent resistance to oxidation, halogens, strong acids and bases.

DuPont perfluorosulfonic acid copolymer is a copolymer that has the general structural formula:

and an equivalent mass (EM) of the copolymer of 1100.

To obtain reinforced membranes, a solution containing 5 wt.% Perfluorosulfonic acid ion exchange polymer, 45 wt.% Water and 50 wt.% A mixture of low molecular weight alcohols from DuPont under the registered NAFION trademark was used.

The porous polymeric material is a porous microstructure characterized by fibers interconnected by nodes, or a porous microstructure that differs significantly from fibrils.

A preferred base material is an expanded polytetrafluoroethylene (PTFE) film, which has a porosity of more than 35 volume percent. Preferably, the porosity is from 70 to 95 volume percent of the total volume of PTFE material. The thickness of the base material is less than 1 mil (0.025 mm), i.e. 25 μm. It is desirable that the thickness is about 0.6 mils (0.015 mm) - 0.8 mils (0.020 mm), most preferably about 0.50 mils (0.013 mm) - 0.75 mils (0.019 mm). This material is commercially available from various companies, such as Gore & Associates. Inc. under the brand name GORE-TEX. The porous microstructure of this base material includes nodes interconnecting fibers that define the internal volume of the base material. In addition, the base material may include PTFE having a porous microstructure comprising predominantly fibrils in the form of a nonwoven material.

The prototype membranes can also be reinforced with a woven or non-woven material bonded on one side to an ion-exchange polymer material. Suitable woven materials may include, for example, expanded porous polytetrafluoroethylene woven fiber webs, extruded or oriented polypropylene fabrics, polypropylene mesh, and non-woven fabrics of gulipropylene and polyester. The disadvantages of the membranes of the prototype are:

1. Not enough high gas density of the membranes. The measurement results showed that at EM = 1100 the coefficients of gas permeability for hydrogen (K) are 5.7-10.0 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° C (see example 17 in table 2, 3), which, in all probability, is associated with insufficient adhesion of the ion-exchange material and the porous polymer matrix.

2. Insufficiently high proton conductivity, since the increased EM = 1100 perfluorosulfonic acid polymer and the presence of a porous polymer material that is part of the composite membrane, which is not a croton-conducting material, violates proton transport through the membrane, especially at high temperature and pressure drops.

3. Insufficient equilibrium moisture absorption due to the increased EM of the ion-exchange polymer and the presence of PTFE and, as a result, the low electrical conductivity of the membranes.

The membrane reinforced with polytetrafluoroethylene for electrolysis of water, described in the prototype, according to the patent WO 0227070, namely, a membrane including proton conductive and porous polymeric materials, can be obtained by sequentially performing the following operations:

- the choice of a porous polymer substrate,

- preparing a liquid composition by mixing a solution of an ion-exchange polymer with a surfactant,

- the combination of a liquid composition with a porous polymeric material,

- heating combined materials and the formation of a reinforced membrane at a temperature of 120-160 ° C,

- removal of surfactants in water and (or) organic medium,

- hydration of the reinforced membranes in a boiling suitable reagent. To obtain a liquid composition, solvents are used that are suitable for the use of ion exchange material and surfactant, and include, for example, alcohols, carbonates, tetrahydrofuran, water, and combinations containing at least one of the above solvents.

Surfactants with a molecular weight of more than 100 are preferably used with ion exchange resins to impregnate the internal volume of the base material. Surfactants having a hydrophobic moiety and hydrophilic moieties can be used. Surfactants having a molecular weight of more than 100 are preferred, which can be classified as anionic, nonionic or amphoteric, such as hydrocarbon or fluorocarbon compounds, for example MERPOO, hydrocarbon-containing surfactants or Zonyl, fluorocarbon surfactants. A preferred surfactant non-ionic material is octylphenoxypolyethoxyethanol having the chemical structure CH ₃ —C (CH ₂ ) ₂ —C (CH ₃ ) —C ₆ H ₄ - (OCH ₂ CH ₂ ) _x OH, where “x” has an average value of 10 This material is known as Triton X-100.

The ion-exchange resins impregnate the porous polymeric material so that the membrane can be called “occluded”, which means that the porous material is impregnated in such a way that the internal pore volume is filled by more than 90, preferably more than 95, and most preferably more than 95 98 percent, so that the finished membrane is significantly less permeable to the volumetric flow of liquids and gas.

In addition to a perfluorinated porous polymer substrate, a polypropylene fabric can be used to prepare an ultrathin reinforced membrane, which is combined with an ion-exchange membrane by lamination using any conventional method, such as hot lamination, ultrasonic lamination, a combination of using glue followed by lamination, hot lamination with air, etc.

Removal of the remaining surfactants in the reinforced membrane is carried out by special treatment. This is achieved by soaking or immersing the membrane in a solution, for example, water, isopropyl alcohol, hydrogen peroxide, methanol and (or) glycerol. At this point, the surfactant that was originally mixed in solution with the ion exchange material is removed. Soaking or immersion causes the membrane to swell, but the ion-exchange substance remains within the internal volume of the base material.

The membrane is then further processed with a suitable boiling agent, such as strong acid (hydrochloric, nitric, chromic) or water, as a result of which the membrane expands slightly in length, width and thickness.

The actual number of repeated procedures depends on the thickness of the polymer substrate, the finished reinforced membrane and the concentration of surfactants. As a rule, the number of procedures is 2 to 4 times.

The reinforced membrane of the prototype can also be obtained by combining a polymer substrate with an ion-exchange polymer in a medium of a mixture of an organic solvent with water without surfactants. However, in this case, without surfactant, such a water content in the solvent mixture does not provide the required surface wetting and further “occluding” of the polymer hydrophobic substrate, as a result of which it is necessary to use a solvent mixture with significantly less water, preferably practically without water.

A solution of an ion-exchange polymer without a surfactant suitable for combining with a polymer porous substrate and the subsequent formation of an airtight reinforced membrane can be obtained by sequentially performing the following operations:

- evaporation of a mixture of an organic solvent and water from the initial solution with the gradual introduction of a non-aqueous solvent,

- drying and grinding of the polymer,

- heating the polymer in a solvent, preferably in a combination of methyl and isopropyl alcohols,

- the combination of the ion-exchange polymer in the environment of anhydrous solvents with a porous polymer substrate,

- heating combined materials and the formation of a reinforced membrane at a temperature of 140 ° C,

- hydration of the reinforced membranes in a boiling suitable reagent. The actual number of repetitive procedures is determined by the desired thickness of the reinforced membrane and depends on the thickness and type of the polymer porous substrate, as well as the water content of the organic solvent / water mixture in the dispersion of the ion-exchange polymer. As a rule, the number of procedures is from 2 to 8 times. To improve the impregnation of a porous polymer substrate, the use of a vacuum impregnation method is used. The disadvantages of the described methods are:

1. The difficulty of combining a hydrophobic porous polymer substrate and an ion-exchange polymer with increased EM = 1100 in a medium of a mixture of an organic solvent with water (up to 45 wt.%), Due to poor wettability and diffusion factors of the polymer substrate, as a result of which up to 90 are completely filled wt.% and more requires the use of surfactants.

2. The need for the introduction of additional process steps to obtain an ion-exchange polymer in an organic solvent with a lower water content, suitable for combining without surfactants.

3. The inability to obtain a reinforced membrane with high electrical conductivity due to the use of surface-active substances having a high sorption capacity for a polymer proton conducting membrane.

4. The tendency to leach out proton-conducting hydrocarbon-containing polymers from the operating time due to the rather high ion-exchange capacity (more than 1.5 mEq / g).

5. The use of the temperature of formation of the reinforced membrane 120-140 ° C can lead to the destruction of ion-exchange groups of the membrane.

6. The complexity of the production methods associated with the multi-stage process and the need to use complex equipment.

The technical result, which is achieved by the inventive composite nanomodified perfluorosulfocathionite membrane with a thickness of 10 μm and above, is to improve the specific proton conductivity and gas permeability of the membranes, increase the stability of linear dimensions during the transition from wet to dry state at high temperatures and pressure, resistance to punctures or tears during operation at high temperatures and pressure drops, high resistance to folding, stability (high rotation) to cracking and exceptional mechanical properties: higher tensile strength, much less elongation, as well as improved contact of the membrane surface with the catalytic layer and, as a result, increased electrochemical characteristics of the membrane and its effective use in water electrolysis at high drops pressure and temperature and other electrochemical devices.

The specified technical result is achieved due to the fact that a composite nanomodified perfluorosulfocathionite membrane was obtained containing 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-dioxalvinyl or perfluoro ether containing 1 or 3 carbon atoms in the alkyl, of the general structural formula:

where R is a unit of perfluoromethylvinyl ether

perfluoropropyl vinyl ether unit

perfluoro-2-methylene-4-methyl-1,3-dioxalane unit

M-H, Li, K, Na;

a = 24.75-18.38 mol.%;

b = 70.25-81.12 mol.%;

c = 5.0-0.5 mol%;

a polymer substrate, organic or inorganic nanomodifiers, characterized by a density of 1.98-2.10 g / cm ³ , a mechanical strength of 16-22 MPa and a gas permeability coefficient of hydrogen (K) of 1-4 × 10 ^-16 m ³ m ^{- 2} Pa ^-1 s ^-1 at a temperature of 20-90 ° C.

The technical result, the achievement of which is provided by the claimed method for producing a composite nanomodified perfluorosulfocathionite membrane, consists in the possibility of a polymer substrate, an ion-exchange polymer and a modifier to be integrated effectively in the membrane so that it increases the electrical conductivity over a wide range of temperature and pressure compared to gas-tight membranes or membranes reinforced with polytetrafluoroethylene. This is due to the fact that the main functional groups of the substrate polymer, the acidic functional groups of the ion-exchange polymer, and the functional groups of the modifier are located close to each other, which apparently facilitates proton transport through the composite membrane.

The method of producing a composite membrane also provides a thin and superthin membrane with a higher ion transport rate, higher strength and low gas permeability. A swollen membrane retains its mechanical strength and dimensional stability and at the same time maintains the desired ionic transport characteristics, electrical resistance and improved electrochemical properties during their long-term operation in water electrolyzers and other electrochemical devices, in contrast to a membrane consisting only of an ion-exchange material and a modifier, or from a polymer substrate and ion-exchange materials.

The specified technical result is achieved due to the fact that in the method for producing a composite nanomodified perfluorosulfocationionite membrane, comprising combining a porous perfluorinated polymer substrate with a perfluorosulfocationionite polymer in a liquid medium and forming a composite membrane, the combination process is carried out in a liquid coprocessor mixture comprising perfluorinated ion exchange perfluoromerized formulas -SO ₃ M, where M is an ion of hydrogen, ammonium or an alkali metal having neither a viscous equivalent weight of 750-890 soluble in a solvent selected from the group consisting of a polar organic solvent, a mixture of polar organic solvents, a mixture of polar and non-polar organic solvents, or a mixture of polar organic solvent with water, wherein sulfonated polysulfone, polyvinyl alcohol are used as a polymer modifier , polyvinylidene fluoride, vinylidene fluoride copolymers, sulfonated polymers and vinylidene fluoride copolymers, and as an inorganic modifier coprocessor mixture contains compounds of titanium, tin, zirconium, germanium, silicon, or mixtures thereof, selected from the group of oxides, phosphates, hydrophosphates, as well as tetraethoxysilane. The combination is carried out at a temperature of 18-30 ° C, and the formation of particles of the modifier on the surface or in the volume of the membrane is carried out at a temperature of 18-110 ° C.

When carrying out the process of obtaining composite nanomodified perfluorosulfocathionite membranes using a coprocessor mixture containing an ion-exchange copolymer with EM = 750-890 and a polymer modifier in a polar organic solvent, the process of combining with a polymer substrate is preferably carried out at a temperature of 18-30 ° C, and the final formation is preferably at a temperature of 50-120 ° C, and when using a coprocessor mixture containing an ion-exchange copolymer with EM 750-890 and an inorganic modifier in the mixture water with a polar organic solvent, or in a mixture of polar and nonpolar organic solvent, the process of combining with a polymer substrate is carried out at a temperature of 18-30 ° C, and the final formation of the membrane at a temperature of 18-110 ° C. The use of the combination temperature above 30 ° C does not contribute to the formation of composite nanomodified perfluorosulfocathionite membranes with a given set of properties. The use of the temperature of formation of a composite nanomodified perfluorosulfocationionite membrane above 120 ° C can lead to the destruction of ion-exchange groups of the membrane. In this case, the combination of the polymer substrate with the coprocessor mixture in the solvent medium is carried out by spraying, soaking, filling, etc.

Introduction to a polymer with EM 750-890, from which a composite nanomodified perfluorosulfocationionite membrane is made, of a third modifying comonomer selected from the group consisting of perfluoro-2-methylene-4-methyl-1,3-dioxolane or perfluoroalkyl vinyl ether containing 1 or 1 in alkyl 3 carbons, allows to streamline the spatial arrangement of the side chains of the polymer containing the group SO ₃ M, thereby forming a certain supramolecular structure, which accelerates the process of "occlusion", improves compatibility with polymeric thermo molecular weight modifier and the substrate and their integration in the formation of the composite membrane.

Moreover, already in the process of synthesis of such polymers with a third comonomer, one can control the cluster-channel structure of membranes and, accordingly, influence their electrochemical and diffusion properties

If to combine with a polymer substrate we use a coprocessor mixture containing the above ion-exchange perfluorosulfopolymer with EM 750-890, soluble in an organic solvent or in a mixture with water and a modifier, the process of wetting and “occluding” proceeds better, and the gas permeability of composite membranes is lower than for membranes obtained by combining an ion-exchange perfluorosulfopolymer with EM 1100 in a solvent medium according to the prototype. The gas permeability coefficient of hydrogen (K) of such composite membranes with a thickness of 10 μm is 1-3.7 × 10 ^-16 m ³ m m ^-2 Ra ^-1 s ^-1 , while for gas-tight modified membranes from 50 μm obtained with contacting the initial membrane (EM) with the liquid composition and modifier, 1-5 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 , and for the reinforced membranes made by combining the polymer substrate with the ion-exchange copolymer according to the prototype, the gas permeability is 5-10 × 10 ^-16 m ³ m m ^-2 Ra ^-1 s ^-1 at a temperature of 20-90 ° C (example 17. table 3).

In the claimed method, the above-mentioned ion-exchange polymer, which is part of the coprocessor mixture, when forming a modifier on the surface or in the volume of the membrane, acts as a matrix, that is, it creates a cluster-channel structure that favors a more uniform distribution of the modifier and, as a result, a higher density and more low gas permeability of the membrane (template synthesis). In addition, the use of such a lyophilic-lyophobic ion-exchange polymer with a lower equivalent weight (750-890) improves compatibility with the polymer substrate and the modifier, provides the necessary adhesion and “occlusion” of the ion-exchange polymer with the polymer substrate, chemical resistance of the membranes (for example, leaching of polymer and inorganic modifier during continuous operation), (see examples 17-19). and also favors the formation of composite membranes, the surface of which has better compatibility with the electrocatalytic mixture in the manufacture of membrane-electrode blocks (OIE).

Such a composite membrane maintains the stability of linear dimensions during operation and maintains increased strength in the wet state. The gas permeability of such membranes during operation does not increase.

In the inventive composite perfluorosulfocathionite membrane, the total content of the monomer with sulfocathionite groups is 24.75-18.38 mol.%, And the content of the modifying perfluorovinyl ether is 0.5-5.0 mol.%.

If the content of perfluorovinyl ether in the perfluorosulfocathionite membrane is less than 0.5 mol%, then it has practically no effect on the properties of the resulting composite membranes (example 9. table 1, example 5, table 2,3). In the case when the content of perfluorovinyl ether in the composite membrane is more than 5.0 mol%, the optimal structure of the composite perfluorosulfocationionite membrane is not formed, while such a membrane does not provide optimal “occluding” and integration of the polymer substrate, ion-exchange polymer and polymer or inorganic modifier (example 13, table 1, example 9, table 2,3), as well as the required mechanical strength.

In the case when the content of the monomer with sulfo groups in the membrane is less than 18.38 mol%, the EM of the copolymer increases and the electrochemical properties of the membranes deteriorate (Example 14, Table 1, Example 8, Table 2.3).

In the case when the content of the monomer with sulfo groups in the membrane is more than 24.75 mol%, the EM will significantly decrease, which makes it difficult to obtain composite nanomodified membranes with high mechanical strength and low gas permeability (example 1, table 1, example 7, table 2 , 3).

According to the claimed method, depending on the purpose, composite perfluorosulfocationionite membranes with a thickness of more than 10 microns, preferably 10-70 microns and most preferably 10-30 microns thick with a content of 24.75-18.38 mol.% Perfluorosulfonomer-containing monomer unit and 5-25 wt. % of a polymer or inorganic modifier located in the bulk or on the surface of the membrane, having an optimal combination of physical and physico-mechanical characteristics: density 1.98-2.10 g / cm ^-3 , gas permeability of hydrogen (K) 1.0-3.7 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° C, while the membranes are uniform in composition and have a tensile strength of 16-22 MPa, high proton conductivity and chemical resistance. The indicated optimal set of properties is ensured by the process conditions, in particular, combining the polymer substrate with a coprocessor mixture containing a perfluorosulfonate ion-exchange copolymer with EM = 750-890, soluble in a polar organic solvent, a mixture of polar organic solvents, or a mixture thereof with water, a mixture of polar and non-polar organic solvent, modifier and solvent at a given temperature in the range of 18-30 ° C, allowing you to enter a given amount of polymer or inorganic esk modifier. The composition of the coprocessor mixture, the required amount of modifier and ion-exchange polymer was determined by the proton conductivity, thickness, strength and gas permeability of the composite membranes and was calculated by the inventors in accordance with their dependencies on the composition of the perfluorosulfocathionite membrane and the rate of “occluding” on the composition of the coprocessor mixture.

In the process of producing composite nanomodified membranes, a coprocessor mixture containing a mixture of the calculated amount of a solution of an ion-exchange polymer in a solvent and a solution of a modifier in a solvent is loaded into the appropriate device, depending on the composition and structure of the composite membrane, and the combination with the selected polymer substrate is performed. If you want to get a membrane with a volume distribution of the modifier, then the coprocessor mixture is loaded into the tank, set the desired temperature (18-30 ° C), put a sample of the polymer substrate, stretched on a metal frame, and combine for a time sufficient to achieve a given amount of adsorbed coprocessor mixture in a porous polymer material. The combination time is determined by the thickness of the composite nanomodified perfluorosulfocathionite membrane, the type of modifier and solvent, EM ion-exchange copolymer, the composition of the coprocessor mixture and is preferably 0.15-2 hours. At the end of the combination, the “occluded” polymer substrate is removed from the container, if necessary, rinsed quickly in the selected solvent and dried until the solvent is completely removed. The drying temperature is set based on the volatility of the solvent. The final formation of the modifier is carried out depending on the type of modifier introduced during treatment in water or aqueous solutions of mineral acids or alkalis at a temperature of 20-95 ° C.

When it is necessary to obtain a composite membrane with a layered distribution of the modifier (on one or both sides of the surface), then a predetermined amount of the coprocessor mixture is loaded into an airbrush, spray gun, etc. and applied to one or both surfaces of the polymer substrate from 2 to 4 times depending on the content ion exchange polymer in a solvent environment. In addition, other combination methods can also be used, for example, spreading with a roller, pouring onto the surface, etc.

The properties of the obtained composite nanomodified perfluorosulfocathionite membranes were determined as follows:

1. The composition and structure of the perfluorinated copolymer was determined by IR spectroscopy on a Perkin-Elmer spectrometer, model 1760.

2. The thickness of the membrane was determined according to TU 301-05-12-89.

3. The full exchange capacity of the membrane was determined according to GOST 17552-72.

4. The density of the membrane was determined according to GOST 14266-81.

5. The specific volume electric resistance of the membrane was determined according to TU 301-05-12-89.

6. Tensile strength and elongation of the membrane were determined according to GOST 11262-80.

7. The humidity of the membrane was determined according to GOST 17554-72.

8. Hydrogen permeability to gas was determined by the method No. 127-78 of Plastpolymer OJSC.

9. The change in linear dimensions was determined by a ruler according to GOST 427-75

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

The following examples illustrate the present invention.

Example 1

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 10 μm. 25 g of a coprocessor mixture is loaded into a capacity of 0.05 L, including a mixture consisting of 17.8 g of an ion-exchange polymer solution containing 19.8 mol.% Perfluorosulfonomer-containing monomer (a) and 5.0 mol.% Modifying monomer (s) structure (E) having EM = 850 (functional group —SO ₃ H) in isopropyl alcohol (concentration 5.2 wt.%) and 7.2 g of a solution of zirconium chloride in water. Then, using the spray method (airbrush), a part of the coprocessor mixture at ambient temperature (20-23 ° C) is applied to both surfaces of a sample of a polymer substrate stretched on a stainless steel metal frame of 70 × 70 mm in size. At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 80 ° C until the solvent is completely removed. The alignment process is repeated three more times.

At the end of the combination, the “occluded” membrane is removed from the container, rinsed quickly in water and dried in a thermostat at a temperature of 80 ° C until the solvent is completely removed. The alignment process is repeated one more time. After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of phosphoric acid (acid concentration of 40 wt.%) Is loaded and heated at a temperature of 80 ° C for 2 hours for the final formation of the membrane structure. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 30 μm with a content of zirconyl phosphate with a particle size of 5-100 nm in an amount of 20 wt.% Is obtained.

Example 2

To obtain a composite membrane, a polymer substrate is used in the form of a sample of a porous polytetrafluoroethylene film 11 μm thick. 50 g of a coprocessor mixture containing a mixture of 35.6 g of an ion-exchange polymer solution containing 22.02 mol.% Perfluorosulfonomer-containing monomer (a) and 4.0 mol.% Modifying monomer (s) are loaded into a 0.1-liter capacity structure (E) having EM = 800 (functional group —SO ₃ H) in isopropyl alcohol (concentration 7.8 wt.%) and 14.4 g of a solution of tetrabutoxytitanium in isopropyl alcohol. After that, a temperature of 23 ° C is set in the container, a sample of the polymer substrate is stretched on a metal frame made of stainless steel with a size of 70 × 70 mm, and alignment is carried out for 10 minutes.

At the end of the alignment, the “occluded” membrane is removed from the container, rinsed quickly in water and dried in a thermostat at a temperature of 80 ° C until the solvent is completely removed. The alignment process is repeated one more time.

After formation, the membrane is placed in a container with a volume of 0.25 L, 50 g of distilled water are charged and heated at a temperature of 40 ° C for 2 hours for the final formation of titanium dioxide in the membrane. Get composite nanomodified perfluorosulfocationionite membrane with a thickness of 25 μm with a content of TiO ₂ with a particle size of 5-250 nm in an amount of 19 wt.%.

Example 3

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 12 μm. 50 g of a coprocessor mixture consisting of 23.5 g of an ion-exchange polymer solution containing 24.75 mol.% Perfluorosulfonomer-containing monomer (a) having EM = 750 (functional group —SO ₃ Li) and 5, 0 mol% of a modifying monomer (c) of structure (D), in dimethylformamide (concentration 4.3 wt.%) And 26.5 g of a solution of polyvinyl alcohol in dimethylformamide (concentration 5 wt.%). Then, a temperature of 23 ° C is set in the container, a sample of the polymer substrate is placed, stretched on a stainless steel metal frame of size 70 × 70 mm, and the alignment is carried out for 20 minutes.

At the end of the combination, the “occluded” membrane is placed in a thermostat and dried at a temperature of 20 ° C until the solvent is completely removed. After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of nitric acid are loaded (concentration of 10 wt.%) And heated at a temperature of 40 ° C for 2 hours for the final formation of the membrane. Get a composite nanomodified perfluorosulfocathionite membrane with a thickness of 25 μm with a polyvinyl alcohol content of 10 wt.%.

Example 4

The process is similar to that in example 1 and differs in that instead of 5 mol.% Modifying monomer (s) add 0.5 mol.%.

Example 5

The process is similar to that shown in example 1 and differs in that instead of 5 mol.% Modifying monomer (s) add 0 mol.%.

Example 6

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 8 μm. 25 g of a coprocessor mixture consisting of 14.15 g of a solution of an ion-exchange polymer containing 18.38 mol.% Perfluorosulfonomer-containing monomer (a) and 3.0 mol.% Modifying monomer (c) of structure (K) are loaded into a 0.05 L container; having EM = 890 (functional group —SO ₃ H) in isopropyl alcohol (concentration 7.3 mass%) and 10.85 g of a solution of zirconium chloride in water. Then, using the syri method (airbrush), part of the coprocessor mixture at an ambient temperature of 20-23 ° C is applied to both surfaces of a sample of a polymer substrate, stretched onto a stainless steel metal frame of size 70 × 70 mm, for 2 minutes. At the end of the combination, the “occluded” membrane is removed from the container, rinsed quickly in water and dried in a thermostat at a temperature of 80 ° C until the solvent is completely removed. The alignment process is repeated two more times. After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of phosphoric acid (acid concentration of 40 wt.%) Is loaded and heated at a temperature of 80 ° C for 2 hours for the final formation of the membrane structure. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 30 μm and a content of zirconyl phosphate with a particle size of 5-150 nm in an amount of 23 wt.% Is obtained.

Examples 7, 8

The process of obtaining modified membranes is carried out analogously to example 1, but the composition of the ion-exchange perfluorosulfopolymer is varied. In example 7, the process is carried out using a membrane containing 28.20 mol.% Perfluorosulfonamide monomer (a), in example 8 - 16.5 mol.% Perfluorosulfonamide monomer (a).

Examples 9, 10

The process of obtaining modified membranes is carried out analogously to example 1, but the structure of the ion-exchange perfluorosulfopolymer is varied. In example 9, the process is carried out using a membrane containing 5.5 mol.% Modifying monomer (C) structure (D), and in example 10, containing 0 mol.% Modifying monomer.

Example 11

To obtain a composite membrane, a polymer substrate is used in the form of a sample of a porous polytetrafluoroethylene film 11 μm thick. 30 g of a coprocessor mixture containing a mixture of 18.4 g of an ion-exchange polymer solution containing 24.75 mol.% Perfluorosulfonomer-containing monomer (a) and 2.0 mol.% Modifying monomer (c) of a structure ( D) having EM = 750 (functional group —SO ₃ H) in ethanol (concentration of 6 wt.%) And 11.6 g of a solution of tin tetrabromide in ethanol (concentration of 10 wt.%). Then, using the spray method (airbrush), part of the coprocessor mixture at an ambient temperature of 20-23 ° C is applied to both surfaces of a sample of a polymer substrate stretched on a stainless steel metal frame of 70 × 70 mm in size. At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 50 ° C until the solvent is completely removed. The alignment process is repeated three more times.

After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of distilled water are charged and heated at a temperature of 60 ° C for 2 hours for the final formation of tin dioxide in the membrane. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 35 μm with a content of tin dioxide with a particle size of 5-150 nm in an amount of 15.1 wt.% Is obtained.

Example 12

To obtain a composite membrane, a polymer substrate is used in the form of a sample of a porous polytetrafluoroethylene film with a thickness of 9 μm. 25 g of a coprocessor mixture containing a mixture of 21 g of an ion-exchange polymer solution containing 24.75 mol.% Perfluorosulfonomer-containing monomer (a) and 2.0 mol.% Modifying monomer (c) of a structure ( D) having EM = 750 (functional group —SO ₃ Li) in dimethylformamide (concentration 4.9 wt.%) And 4 g of a solution of sulfonated polysulfone (SPSF) with an exchange capacity of 1.87 mEq / g in dimethylformamide (concentration 5 wt.%). Then, using the spray method (airbrush), part of the coprocessor mixture at an ambient temperature of 20-23 ° C is applied to both surfaces of a sample of a polymer substrate stretched on a stainless steel metal frame of 70 × 70 mm in size. At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 100 ° C until the solvent is completely removed. The combining process is repeated 4 more times. After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of nitric acid are loaded (concentration of 10 wt.%) And heated at a temperature of 40 ° C for 2 hours for the final formation of the membrane. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 35 μm with a sulfonated polysulfone content of 10 wt.% Is obtained.

Example 13

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 13 μm. 50 g of a coprocessor mixture consisting of 46 g of an ion-exchange polymer solution containing 24.75 mol.% Perfluorosulfonomer-containing monomer (a) and 2.0 mol.% Modifying monomer (c) of structure (D) are loaded into a 0.1-liter capacity having EM = 750 (functional group —SO ₃ Li) in dimethylformamide (concentration 4.9 wt.%) and 4 g of a solution of polyvinylidene fluoride PVDV in dimethylformamide (concentration 5 wt%). Then, the temperature is set in the tank at 25 ° C, a sample of the polymer substrate, stretched onto a stainless steel metal frame of 70 × 70 mm in size, is placed in it, and alignment is carried out for 30 minutes.

At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 100 ° C until the solvent is completely removed. The combining process is repeated 3 more times.

After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of nitric acid are loaded (concentration of 10 wt.%) And heated at a temperature of 40 ° C for 2 hours for the final formation of the membrane. A composite nanomodified first sulfonation-cationionite membrane with a thickness of 30 μm and a polyvinylidene fluoride content of 5 wt.% Is obtained.

Example 14

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 10 μm. 50 g of a coprocessor mixture consisting of 37 g of a solution of an ion-exchange polymer containing 22.02 mol% of perfluorosulfonomer-containing monomer (a) and 0.5 mol% of a modifying monomer (c) of structure (D) are loaded into a 0.1-liter capacity having EM = 800 (functional group —SO ₃ Li) in dimethylformamide (concentration 4.5 wt.%) and 3 g of a solution of sulfonated copolymer of vinylidene fluoride with hexafluoropropylene (CSPVDFGFP) in dimethylformamide (concentration 4.5 wt.%). Then, a temperature of 25 ° C is set in the container, a sample of the polymer substrate is placed, stretched on a stainless steel metal frame of size 70 × 70 mm, and the alignment is carried out for 50 minutes.

At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 100 ° C until the solvent is completely removed.

After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of nitric acid are loaded (concentration of 10 wt.%) And heated at a temperature of 40 ° C for 2 hours for the final formation of the membrane. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 25 μm is obtained with a sulfonated copolymer of vinylidene fluoride with hexafluoropropylene 4.1 wt.%.

Example 15

To obtain a composite membrane using a polymer substrate in the form of a sample of a porous film of polytetrafluoroethylene with a thickness of 15 μm. 50 g of a coprocessor mixture consisting of 10.0 g of an ion-exchange polymer solution containing 22.02 mol.% Perfluorosulfonomer-containing monomer (a) and 4.0 mol.% Modifying monomer (c) of structure (E) are loaded into a 0.15 L container ), having EM = 800 (functional group —SO ₃ H), in ethanol (concentration of 12.5 wt.%) and 40 g of a solution of tetraethoxysilane in ethanol (1: 1). Then, the temperature is set in the tank at 25 ° C, a sample of the polymer substrate is placed, stretched on a stainless steel metal frame of size 70 × 70 mm, and the alignment is carried out for 60 minutes.

At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 70 ° C until the solvent is completely removed.

After that, the membrane is placed in a container with a volume of 0.25 L, 50 g of hydrochloric acid (concentration 15 wt.%) Are loaded and heated at a temperature of 70 ° C for 2 hours for the final formation of the membrane. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 35 μm with a content of silicon dioxide of a particle size of 10-250 nm in an amount of 9.8 wt.% Is obtained.

Example 16

To obtain a composite membrane, a polymer substrate is used in the form of a sample of a porous polytetrafluoroethylene film 11 μm thick. 50 g of a coprocessor mixture consisting of 15 g of a solution of an ion-exchange polymer containing 19.8 mol% of a perfluorosulfonomer-containing monomer (a) and 5.0 mol% of a modifying monomer (c) of a structure (E) are loaded into a 0.15 liter capacity, having EM 850 (functional group —SO ₃ H) in ethanol (concentration of 12 wt.%) and 35 g of a solution of zirconium tetrachloride in 25 g of ethanol. Then, the temperature is set in the tank at 25 ° C, a sample of the polymer substrate is placed, stretched on a stainless steel metal frame of size 70 × 70 mm, and the combination is carried out for 40 minutes. At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 70 ° C until the solvent is completely removed.

After that, the membrane is placed in a container with a volume of 0.15 L, 20 g of a 0.4 M sodium hydroxide solution are loaded and kept at a temperature of 20-23 ° C for 0.25 hours for the final formation of zirconia in the membrane, then washed with water. They are placed in a container with a volume of 0.15 L with 50 g of a 3.5 M hydrochloric acid solution and incubated for 1 h at a temperature of 90-95 ° C. A composite nanomodified perfluorosulfocationionite membrane with a thickness of 30 μm with a content of zirconium dioxide with a particle size of 10-250 nm in an amount of 12.4 wt.% Is obtained.

Example 17 (patent WO No. 0227070)

To obtain a reinforced membrane, a polymer substrate is used in the form of a sample of a porous film of polytetrafluoroethylene 13 μm thick (Gore Tech) and a solution containing 5 wt.% DuPont ion-exchange perfluorosulfonate polymer having EM = 1100 (-SO ₃ H functional group) in isopropyl alcohol, which is prepared from a 5% DuPont polymer solution (EM = 1100) in a mixture of isopropyl alcohol (50 wt.%) and water (45 wt.%). Obtaining is carried out by sequentially carrying out the following operations: evaporation of a mixture of an organic solvent and water from the initial solution with the gradual introduction of a non-aqueous solvent (carbon tetrachloride), drying and grinding of the obtained polymer, dissolution in isopropyl alcohol and obtaining 20 g (5 wt.%) Solution of perfluorosulfonate polymer DuPont company having EM = 1100 (functional group —SO ₃ H) in isopropyl alcohol.

Then, the resulting solution by spray method (airbrush) at an ambient temperature of 20-23 ° C is applied to both surfaces of a sample of a polymer substrate, stretched on a stainless steel metal ring with a diameter of 70 mm, for a period of time sufficient to achieve maximum "occlusion". At the end of the combination, the “occluded” membrane is dried in a thermostat at a temperature of 140 ° C for 30 seconds. The combining and drying process is repeated 4 more times. After drying, a reinforced membrane with a thickness of 35 μm was obtained. The membrane was then boiled in distilled water for 30 minutes at atmospheric pressure to swell the reinforced membrane.

Example 18 (according to the patent of the Russian Federation No. 2426750)

To obtain a modified membrane, a perfluorosulfocationionite membrane is used, made of a copolymer containing 20.7 mol% of a perfluorosulfonomer-containing monomer (a) and 0.5 mol% of a modifying monomer (c) of structure (D) having EM = 800 (-SO functional group) ₃ Li) and a thickness of 40 μm. 50 g of a liquid composition containing a mixture of 8 g of a solution of an ion-exchange polymer with EM = 750 (functional group —SO ₃ H) in isopropyl alcohol (concentration of 10 wt.%) And 42 g of a solution of chloroxide are loaded into a 0.15 L container zirconium in water (concentration of 18 wt.%). Then, a temperature of 80 ° C is set in the container, a 60 × 60 mm sample of the membrane is placed and contacted for 8 hours. At the end of the contact, the membrane with the sorbed liquid composition is removed from the container, rinsed quickly in water and dried in an oven at a temperature of 80 ° C. until the solvent is completely removed. After that, the membrane is placed in a 0.15 L container, 50 g of phosphoric acid (acid concentration of 40 wt.%) Is loaded and heated at a temperature of 80 ° C for 2 hours for the final formation of the membrane structure. Get a modified perfluorosulfocathionite membrane with a zirconyl phosphate content with a particle size of 5-250 nm in an amount of 20 wt.%.

Example 19 (US patent No. 6059943)

A suspension of zirconium phosphate is prepared by quickly adding a solution of Zr (NO ₃ ) ₄ · 5H ₂ O to 85% phosphoric acid. The suspension is placed in a filter funnel with a filter from a film of porous polytetrafluoroethylene film with a thickness of 13 μm and a vacuum is applied. Filtration is stopped after about 10 minutes. The vacuum is turned off, the remaining liquid is removed and the filter is transferred to a flask containing boiling 85% phosphoric acid. Heating is continued for seven days. At the end of the process, the membrane is removed from the flask and again placed in a filter funnel. The process of forming zirconium phosphate is repeated. The resulting memboana is washed in demineralized water. After drying, a reinforced membrane with a thickness of 35 μm was obtained.

The process parameters and properties of the composite membranes of example 1 and the following examples are shown in tables 1 and 2.

Example 20

A modified perfluorodosulfocathionite membrane having EM 890 (functional group —SO ₃ H) and a thickness of 30 μm, containing 23 wt.% Zirconyl phosphate obtained in Example 6, was used in the manufacture of MEA for the electrolysis of water.

To obtain a cathode catalyst in a glass container, platinum black (particle size 60 nm) is mixed with a solution of an ion-exchange polymer (EM 890, group —SO ₃ H) obtained in Example 11 (mixture 1).

To obtain an anode catalyst in a glass container, platinum black and iridium black are mixed in a 1: 1 ratio (particle size 60 nm) with a solution of an ion-exchange polymer (EM 850, group —SO ₃ H) obtained according to Example 11 (mixture 2).

Mixture 1 is applied to one of the surfaces of the aforementioned air-dry membrane by smearing the mixture with a layer of such a thickness that, after drying, the cathode material layer has a thickness of 4 μm. Then the membrane is placed in a thermostat and treated with the next stepwise rise in temperature: it is kept at 20-22 ° С for 10 minutes, at 60 ° С - 40 minutes, at 80 ° С - 20 minutes, at 90 ° С - 20 minutes. After that, the membrane is removed from the thermostat, cooled to room temperature, and in the same way, a mixture of 2 is applied on its other surface with a layer of such a thickness that after drying the layer of anode material has a thickness of 5 μm, then it is again placed in a thermostat and heat treated in the manner described above. For testing in a water electrolyzer, a membrane with electrode layers is placed between porous titanium current collectors with down conductors, the assembly obtained is compacted with a plate screed, immersed in a vessel with distilled water and an electric current of 0.5 A / cm ^{2 is} supplied at 90 ° C in within 1 hour. Then the assembly is installed in the cell for electrolysis of deionized water. The voltage on the cell is 1.43 V at a current density of 1 A / cm ² and a temperature of 100 ° C. The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

zirconyl phosphate content 23 wt.% electrical resistance 8.1 ohm cm tensile strength 21 MPa relative extension 51.8% linear resizing 1.5 × 1.5% gas permeability without changes

Example 21

A modified perfluorosulfocathionite membrane having an EM 750 (functional group —SO ₃ H) and a thickness of 25 μm, with a content of 10 wt.% Polyvinyl alcohol obtained in Example 3, was used in the manufacture of the MEA for the electrolysis of water.

To obtain a cathode catalyst in a glass container, platinum black (particle size 60 nm) is mixed with a solution of an ion-exchange polymer (EM 850, group -SO ₃ H) obtained in Example 3 (mixture 1).

To obtain the anode catalyst in a glass container, platinum black and iridium black are mixed in a ratio of 1: 1 (particle size 60 nm) with an ion-exchange polymer solution (EM 850, group -SO ₃ H) obtained according to Example 3 (mixture 2).

Mixture 1 is applied to one of the surfaces of the aforementioned air-dry membrane by smearing the mixture with a layer of such a thickness that, after drying, the cathode material layer has a thickness of 4 μm. Then the membrane is placed in a thermostat and treated with the next stepwise rise in temperature: it is kept at 20-22 ° С for 10 minutes, at 60 ° С - 40 minutes, at 80 ° С - 20 minutes, at 90 ° С - 20 minutes. After that, the membrane is removed from the thermostat, cooled to room temperature, and in the same way, a mixture of 2 is applied on its other surface with a layer of such a thickness that after drying the layer of anode material has a thickness of 5 μm, then it is again placed in a thermostat and heat treated in the manner described above. For testing in a water electrolyzer, a membrane with electrode layers is placed between porous titanium current collectors with down conductors, the assembly obtained is compacted with a plate screed, immersed in a vessel with distilled water and an electric current of 0.5 A / cm ^{2 is} supplied at 90 ° C in within 1 hour. Then the assembly is installed in the cell for electrolysis of deionized water. The voltage on the cell is 1.39 V at a current density of 1 A / cm ² and a temperature of 100 ° C. The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

zirconyl phosphate content 20 wt.% electrical resistance 7.8 ohm cm tensile strength 18 MPa relative extension 64.8% linear resizing 2 × 2% gas permeability without changes

Example 22

A modified perfluorosulfocathionite membrane having an EM 800 (functional group —SO ₃ H) and a thickness of 25 μm, containing 5 wt% of a sulfonated copolymer of vinylidene fluoride with hexafluoropropylene, obtained according to Example 14, was used in the manufacture of OIE for water electrolysis. Obtaining the OIE and testing in a water electrolyzer is carried out as in Example 21, and to obtain the cathode and anode catalyst, a solution of an ion-exchange polymer (EM 800, group -SO ₃ H) obtained in Example 5 (mixture 1) is used, and to obtain an anode catalyst - a solution of an ion-exchange polymer (EM 850, group —SO ₃ H) obtained in Example 5 (mixture 2).

The voltage on the cell is 1.38 V at a current density of 1 A / cm ² and a temperature of 100 ° C. The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

sulfonated copolymer content vinylidene fluoride with hexafluoropropylene 5 wt.% electrical resistance 7.8 ohm cm tensile strength 18 MPa relative extension 71.8% linear resizing 2 × 2% gas permeability without changes

Example 23

A modified perfluorosulfocathionite membrane having an EM 750 (functional group —SO ₃ H) and a thickness of 35 μm, containing 15.1 wt.% Tin dioxide obtained according to Example 11, was used in the manufacture of OIE for the electrolysis of water.

The preparation of the OIE and the testing in the water electrolyzer are carried out as in Example 21, but to obtain the cathode catalyst, use a solution of the ion-exchange polymer (EM 750, group -SO ₃ H) obtained in Example 2 (mixture 1), and to obtain the anode catalyst, use ion-exchange polymer (EM 750, group -SO ₃ H) obtained in example 2 (mixture 2).

The voltage on the cell is 1.36 V at a current density of 1 A / cm ² and a temperature of 100 ° C. The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

tin dioxide content 15.1 wt.% electrical resistance 7.3 ohm cm tensile strength 20 MPa relative extension 65.8% linear resizing 2 × 2% gas permeability without changes

Example 24

A modified perfluorosulfocathionite membrane having an EM 750 (functional group —SO ₃ H) and a thickness of 35 μm, containing 10.0 wt.% Sulfonated polysulfone obtained in Example 12 was used in the manufacture of the MEA for the electrolysis of water.

The process of obtaining a cathodic and anodic catalyst is carried out analogously to example 21, and a solution of an ion-exchange polymer (EM 750, group -SO ₃ H) obtained in example 2 is used as a solution.

The assembly is installed in a cell for electrolysis of deionized water. The voltage on the cell is 1.43 V at a current density of 1 A / cm ² and a temperature of 120 ° C (pressure 25 Ati). The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

sulfonated polysulfone content 15.1 wt.% electrical resistance 7.8 ohm cm tensile strength 22 MPa relative extension 50.2% linear resizing 1 × 1% gas permeability without changes

Example 25

A modified perfluorosulfocathionite membrane having an EM 850 (functional group —SO ₃ H) and a thickness of 30 μm, containing 15.1 wt.% Zirconium oxide obtained according to Example 16, was used in the manufacture of OIE for water electrolysis.

The process of obtaining a cathodic and anodic catalyst catalyst is carried out analogously to example 21, and a solution of an ion-exchange polymer (EM 850, group -SO ₃ H) obtained in example 8 is used as a solution.

The assembly is installed in a cell for electrolysis of deionized water. The voltage on the cell is 1.41 V at a current density of 1 A / cm ² and a temperature of 120 ° C (pressure 25 Ati). The cell works stably for 4000 hours without changing the indicators. Then the process is stopped and the OIE is removed from the cell. A visual inspection of the OIE does not observe any changes.

The membrane after operation has the following characteristics:

zirconia content 15.1 wt.% electrical resistance 7.2 ohm cm tensile strength 20 MPa relative extension 60% linear resizing 1 × 1% gas permeability without changes

Example 26

A composite membrane with a thickness of 30 μm containing zirconium hydrogen phosphate obtained in Example 19 was used in the manufacture of the OIE for water electrolysis. Obtaining the OIE and testing in a water electrolyzer is carried out, as in example 21. The voltage on the cell is 1.72 V at a current density of 1 A / cm ² and a temperature of 120 ° C. The cell worked for 100 hours, after which the voltage on the cell increased to 2.75 V. The process was stopped and the OIE was removed from the cell. After operation, the membrane became fragile, which did not allow us to determine its main characteristics.

Example 27

A modified gas-tight perfluorosulfocathionite membrane having EM 950 (functional group —SO ₃ H) and a thickness of 40 μm, containing 20 wt.% Zirconyl phosphate, prepared according to Example 18, was used in the manufacture of OIE for water electrolysis.

Obtaining the OIE and testing in the electrolyzer of water is carried out, as in example 25. The voltage on the cell is 1.61 V at a current density of 1 A / cm ² and a temperature of 120 ° C. The cell works stably for 3000 hours without changing the indicators. The voltage on the cell becomes 1.66 V. The process is stopped and the OIE is removed from the cell.

The membrane after operation has the following characteristics:

zirconium oxide content 15.1 wt.% tensile strength 12.4 MPa electrical resistance 11.91 ohm cm relative extension 105.8% linear resizing 6.5 × 6.5% gas permeability 8-12.3 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1

Example 28

A reinforced membrane with a thickness of 30 μm, obtained according to example 17, was used in the manufacture of the OIE for electrolysis of water. Obtaining the OIE and testing in the electrolyzer of water is carried out, as in example 25. The voltage on the cell is 1.62 V at a current density of 1 A / cm ² and a temperature of 120 ° C. The cell worked for 3000 hours. The voltage on the cell becomes 1.7 V. The process is stopped and the OIE is removed from the cell.

The membrane after operation has the following characteristics:

tensile strength 13.7 MPa electrical resistance 14.21 ohm cm relative extension 99.8% linear resizing 6 × 6% gas permeability 6-11.3 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1

Composite nanomodified membranes and the methods for their preparation described in the examples are preferred embodiments of the invention and do not limit the essence and scope of the invention. Other examples and other uses of composite nanomodified membranes are possible without departing from the inventive concept set forth in the claims.

As can be seen from the above data, the inventive composite nanomodified perfluorosulfocathionite membrane, which provides improved performance when working in water electrolysis cells, simultaneously includes units of tetrafluoroethylene, perfluorosulfonate vinyl ether and a third modifying perfluorinated comonomer selected from the group of perfluoro-2-methylene-4-methyl-1, 3-dioxalan and perfluoroalkylvinyl ether containing 1 or 3 carbon atoms in the alkyl, a polymer substrate and a polymer or inorganic modifier, in t while the known membranes suitable for use in water electrolysis cells contain only tetrafluoroethylene and perfluorosulfonate vinyl ether units and a polymer substrate (US Pat. WO 0227070) or tetrafluoroethylene, perfluorosulfonate vinyl ether and third modifying perfluorinated comonomer selected from perfluoro-2 group methylene-4-methyl-1,3-dioxalane and perfluoroalkyl vinyl ether containing 1 or 3 carbon atoms in the alkyl, and a polymer or inorganic modifier (US Pat. RF2426750) or a polymer substrate and an inorganic modifier (US Pat. US 6059943).

The presence of a third modifying monomer in a perfluorosulfonate ion-exchange polymer in an amount of 0.5-5.0 wt.% Allows you to create a specific supramolecular structure, which is more uniform and ordered, which makes it possible to produce thin and ultrafine by combining it with a polymer substrate and a polymer or inorganic modifier composite nanomodified membranes with higher density, mechanical strength, low elongation and low gas permeability than known s membranes. So, the density of the inventive composite nanomodified membranes with a thickness of 25-35 microns with EM 750-890 is 1.98-2.1 g / cm ³ , strength 16-22 MPa, elongation 50-80%, and the coefficient of gas permeability of hydrogen (K) is 1-3.7 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° C (examples of Table 3).

The density of the modified membranes based on known membranes containing only tetrafluoroethylene and perfluorosulfonate vinyl ether units with the same EM and the same thickness is 1.83-1.91 g / cm ³ , strength 14-15 MPA, elongation 97-103% and the gas permeability coefficient (K) is 5-11 × 11 ^-16 cm ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° С, Pat. WO 0227070, RF 2426750, USA 6059943 (pr. 17-19 Table 2, 3).

A more uniform cluster-channel structure of the aforementioned membrane, including the third modifying monomer, provides the necessary "occluding" of the polymer substrate and uniform distribution of the inorganic and polymer modifier in the membrane, which facilitates the regulation of the formation of the structure and properties of the inventive composite nanomodified membranes and improves their proton conductivity, mechanical strength and stability of linear dimensions in the dry and hydrated state, as well as chemical resistance st.

The complex of improved properties of the claimed membranes contributes to their effective use in water electrolyzers, including at high pressure drops, while when using known membranes with the same EM, the electrochemical characteristics are worse than in the claimed membranes (example 17-19, table 3 )

The inventive composite nanomodified membrane containing 0.5-5.0 mol% of the third modifying monomer has a significantly lower thickness, electrical resistance, and polymer or inorganic modifiers are not washed out of the membrane and, accordingly, the membrane retains its electrochemical and physical mechanical characteristics for a longer time. So, after operating for 4000 hours in a water electrolyzer with the inventive composite nanomodified membrane with an EM 750-890 with a thickness of 25-35 μm, the electrical resistance, mechanical strength, elongation and stability of linear dimensions remained practically unchanged, while the voltage of the cell remained unchanged 1.38-1.43 V at a current density of 1.0 A / cm ² at a temperature of 100-120 ° C (examples 20-25), while after operating for 3000 hours the modified membrane according to US Pat. RF 2426750 mechanical strength decreased from 13.8 to 12.4 MPa, electrical resistance increased from 11.1 to 11.91 Ohm · cm, and the cell voltage increased from 1.61 to 1.66 V at a current density of 1.0 A / cm ² (example 18). In addition, when operating the reinforced membrane according to the prototype (US Pat. WO. 0227070) after 3000 hours, the electrical resistance of the membrane increased from 13.4 to 14.2 Ohm · cm, the strength of the membrane decreased from 15.5 to 13.4 MPa wt.% and the cell voltage increased from 1.62 to 1.7 V (example 27).

As can be seen from the above data, the claimed method in comparison with the known method according to the prototype allows quite easily without the introduction of surface-active substances in the production process to achieve the required properties of the obtained composite nanomodified perfluorosulfocathionite membranes (density, gas permeability coefficient) due to changes in the content of modifying ion-exchange polymer unit and reducing the equivalent weight to 750-890, as well as due to the process of combining the polymer substrate with an ion-exchange polymer and a modifier in a coprocessor mixture of an ion-exchange polymer and a modifier in a solvent medium, varying the type and amount of both the polymer and inorganic modifier and the process temperature. It was unexpectedly found that the use of a modifier in the composition of the coprocessor mixture during membrane formation contributes to a greater membrane compaction than without a modifier, which leads to an improvement in the mechanical strength of the membranes, creep, a decrease in the linear dimensions of the membranes at high pressure, and resistance to punctures or ruptures during work at high temperatures and pressures and ensure high ionic conductivity at elevated working temperatures (up to 100 ° C and above).

The use of an ion-exchange copolymer with EM 750-890 as a part of the coprocessor mixture significantly facilitates the wetting of the porous polytetrafluoroethylene film, spreading of the coprocessor mixture over the surface, an increase in the rate of polymer diffusion into the pores and “occluding”, ensures the formation of a gas-tight composite membrane and high electrochemical characteristics of the membranes. According to the prototype method, a reinforced membrane is obtained by carrying out the process of combining a polymer substrate only with an ion-exchange polymer in a solvent medium, in this regard, controlling the properties of the resulting reinforced membranes containing tetrafluoroethylene and perfluorosulfonate vinyl ether with EM1100 is possible only by changing the thickness of the deposited layer, with This in the process of obtaining used surfactants, which does not allow to obtain membranes with an optimal set of properties and leads to electrocatalyst equalization. The inventive method allows to obtain composite nanomodified perfluorosulfocathionite membranes with the following optimal set of properties: EM 750-890, thickness from 10 μm, preferably 25-35 μm, density 1.98-2.10 g / cm ³ , strength 16-22 MPa, relative elongation of 50-80%, the coefficient of gas permeability of hydrogen (K) 1-5 × 10 ^-16 m ³ m m ^-2 Pa ^-1 s ^-1 at a temperature of 20-90 ° C, the change in linear dimensions of 1-3% and electrical resistance 7 -9 ohm cm The inventive membrane can be used in water electrolyzers at various temperatures and pressures (examples 20-28) and other electrochemical devices.

Table 1 Properties of the samples of the starting perfluorosulfopolymers (PPSM) Sample No. The composition of the PPSM, mol.% EM Functional group TFE PFSM PFEV one 2 3 four 5 7 one 69.8 28,2 2 structure D 700 SO ₃ H 2 73.25 24.75 2 structure D 750 SO ₃ H 3 70.25 24.75. 5 structure D 750 SO ₃ Li four 77.48 22.02 0.5 structure D 800 SO ₃ Li 5 73.98 22.02 4.0 structure E 800 SO ₃ H 6 73.98 22.02 4.0 structure K 800 SO ₃ Li 7 75,2 19.8 5 structure E 850 SO ₃ H 8 79.52 19.80 0.5 structure E 850 SO ₃ H 9 80.2 19.8 0 850 SO ₃ H 10 77.62 18.38 4.0 structure K 890 SO ₃ Li eleven 78.62 18.38 3 structure K 890 SO ₃ H 12 76.12 18.38 5.5 structure D 890 SO ₃ H 13 72.48 22.02 5.5 structure D 850 SO ₃ H fourteen 79.0 16.5 4,5 structure D 950 SO ₃ Li

Thus, the composite nanomodified perfluorosulfocathionite membrane is suitable for use in low and high pressure water electrolyzers and other electrochemical devices at a wider range of pressures and temperatures than are known in the world.

Claims (13)

1. A composite nanomodified perfluorosulfocathionite membrane containing 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 or perfluoroalkylvinyl 1-ether, containing 1 alkyl alkyl perfluoride carbon, General structural formula:

where R is a unit of perfluoromethylvinyl ether

perfluoropropyl vinyl ether unit

perfluoro-2-methylene-4-methyl-1,3-dioxalane unit

MH, Li, K, Na;
a = 24.75-18.38 mol.%;
b = 70.25-81.12 mol.%;
c = 5.0-0.5 mol%;
a polymer substrate, organic or inorganic nanomodifiers, characterized by a density of 1.98-2.10 g / cm ³ , a mechanical strength of 16-22 MPa and a gas permeability coefficient of hydrogen (K) of 1-4 × 10 ^-16 m ³ m ^{- 2} Pa ^-1 s ^-1 at a temperature of 20-90 ° C. 2. The membrane according to claim 1, characterized in that as the polymer substrate, the membrane contains polytetrafluoroethylene in the form of a porous film with a thickness of 8-25 microns. 3. The membrane according to claim 1, characterized in that, as an organic nanomodifier, the membrane contains polyvinylidene fluoride, polyvinylidene fluoride copolymers, sulfonated polymers and polyvinylidene fluoride copolymers. 4. The membrane according to claim 1, characterized in that, as an inorganic nanomodifier, the membrane contains compounds of titanium, tin, zirconium, germanium, or mixtures thereof, selected from the group: oxides, phosphates, hydrogen phosphates. 5. The membrane according to claim 1, characterized in that the membrane contains silicon oxide as an inorganic nanomodifier. 6. A method of producing a composite nanomodified perfluorosulfocathionite membrane, comprising combining a porous perfluorinated polymer substrate — a porous platetrafluoroethylene film with a perfluorosulfocathionite polymer in a liquid medium and forming a composite membrane, characterized in that the combination process is carried out in a coprocessor mixture including an ion exchange exchange modifier and organic or aqueous organic medium, and hydrocarbons are used as a modifier e polymers, fluoropolymers, perfluorinated polymers or mixtures thereof, inorganic compounds or mixtures thereof. 7. The method according to claim 6, characterized in that for combining use a coprocessor mixture containing a perfluorinated ion-exchange copolymer with functional sulfo groups of the formula —SO ₃ M, where M is a hydrogen, ammonium or alkali metal ion having an equivalent weight of 750-890, and a modifier soluble in a solvent selected from the group consisting of: a polar organic solvent, a mixture of polar organic solvents or a mixture thereof with water, a mixture of polar and non-polar organic solvents. 8. The method according to claim 6, characterized in that the liquid composition as a modifying polymer comprises polyvinyl alcohol, sulfonated polysulfone, polyvinylidene fluoride, polyvinylidene fluoride copolymers, sulfonated polymers and polyvinylidene fluoride copolymers. 9. The method according to claim 6, characterized in that, as an inorganic compound, the liquid composition contains titanium, tin, zirconium, germanium, silicon compounds or mixtures thereof selected from the group: chlorides, oxychlorides, oxides, hydroxides, phosphates, hydrophosphates, alcoholates . 10. The method according to claim 6, characterized in that, as a modifying compound, the liquid composition contains tetraethoxysilane. 11. The method according to claim 6, characterized in that the process of combining with the coprocessor mixture is carried out at a temperature of 18-30 ° C. 12. The method according to claim 6, characterized in that the process of forming a composite membrane is carried out at a temperature of 50-120 ° C. 13. The method according to claim 6, characterized in that the composite membrane contains a bulk or layered distribution structure of the modifier.