Perfluorosulfonic acid resin not containing perfluorooctanoic acid or perfluorooctane sulfonic acid, preparation method thereof, catalyst layer and hydrogen fuel cell membrane electrode

Abstract

The invention provides a perfluorosulfonic acid resin without perfluorooctanoic acid or perfluorooctane sulfonic acid, a preparation method thereof, a catalyst layer and a hydrogen fuel cell membrane electrode. The perfluorinated sulfonic acid resin is formed by copolymerization of monomers containing perfluorinated oxaolefin sulfonyl fluoride and water-soluble perfluorinated oxaolefin sulfonate through an emulsion method, and the perfluorinated oxaolefin sulfonate is obtained by hydrolysis of the perfluorinated oxaolefin sulfonyl fluoride through alkali liquor. The mass ratio of the perfluorinated oxaolefin sulfonyl fluoride to the perfluorinated oxaolefin sulfonate is (4-8): 1. The perfluorinated oxaolefin sulfonate is a double-bond-containing perfluorinated surfactant, can be used as an emulsifier and can also be used as an active polymerizable monomer to participate in a polymerization reaction, and compared with resin which does not contain a double-bond emulsifier in the prior art, the perfluorinated sulfonic acid resin disclosed by the invention has the advantages of higher resin purity and lower cost. The composite material has good proton conductivity, oxygen permeability, mechanical strength, durability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen fuel cells, and more specifically, to a perfluorosulfonic acid resin free of perfluorooctanoic acid or perfluorooctanesulfonic acid, a preparation method thereof, a catalyst layer and a hydrogen fuel cell membrane electrode. Background Art

[0002] In the polymerization process of fluorinated polymers, it is usually necessary to add a certain amount of fluorinated emulsifier. Generally, perfluorooctanoic acid (PFOA) or its salts, and perfluorosulfonic acid (PFOS) or its salts are widely used as fluorinated emulsifiers in polymerization reactions. However, as early as 2001, the U.S. Environmental Protection Agency (EPA) proposed a ban on the use of PFOS and PFOA. For this reason, 3M has also specially developed perfluorobutyl sulfonic acid (PFBS) to replace PFOS and PFOA. PFBS has a short fluorocarbon chain and no obvious persistent bioaccumulation. It can be excreted from the body with human metabolism in a short time, and its decomposition products are non-toxic. Its products have been proven to be protective and environmentally friendly through a large number of tests, and have now been approved by EPA and other environmental protection agencies in the world. Since then, major fluoropolymer manufacturers at home and abroad have been committed to developing new fluorinated surfactants to replace PFOA and PFOS for use in polymerization reactions. The fluorinated emulsifiers disclosed for use in the polymerization process include: perfluoropolyether (CN101218264B), cyclic fluorinated compounds (CN102089335A), and fluorinated emulsifiers that replace perfluorooctanoic acid and its salts (CN101745338A, CN101287766, and CN101291987). The above fluorinated emulsifiers can replace PFOA / PFOS for the emulsion polymerization of fluorinated monomers, and the aqueous emulsions of their fluorinated polymers do not show the adverse effects of fluorinated octanoic acid or its salts. From the contents disclosed in the above patent documents, we can also know that the existing fluorinated emulsifiers disclosed are all effective. Although the toxicological characteristics of fluorinated emulsifiers have been solved, these perfluoro emulsifiers still remain in the polymer after the polymerization reaction is completed. Moreover, these emulsifiers are all new compounds, and their impact on the environment has not been fully and deeply evaluated, which poses environmental risks. It is worth noting that the inventors discovered during the research process that in certain specific application fields, such as hydrogen fuel cell membrane electrode, when fluorinated emulsifiers are present in the ionomers used in the catalyst layer, it will affect the performance of the catalyst layer, such as durability. In order to remove them to ensure the purity of the ionomer, complicated post-processing operations must be performed, which will destroy the initial performance of the ionomer after synthesis. Summary of the invention

[0003] The object of the present invention is to provide a perfluorosulfonic acid resin that does not contain perfluorooctanoic acid or perfluorooctane sulfonic acid, a preparation method thereof, a catalyst layer and a hydrogen fuel cell membrane electrode. The perfluorosulfonic acid resin is copolymerized by an emulsion method using monomers including perfluorooxaolefin sulfonyl fluoride and a water-soluble perfluorooxaolefin sulfonate obtained by hydrolyzing the monomers with alkaline solution, wherein the perfluorooxaolefin sulfonyl fluoride and the perfluorooxaolefin sulfonate are mixed and used in a specific ratio, and the perfluorooxaolefin sulfonyl fluoride can synergistically enhance the emulsifier effect of the same perfluorooxaolefin sulfonate, thereby avoiding the use of any other fluorinated emulsifier and avoiding environmental risks, and avoiding the residual fluorinated emulsifier or subsequent impurity removal operation to affect the performance of the fluorinated sulfonic acid resin isoionomer in the hydrogen fuel cell catalyst layer, especially the durability.

[0004] In order to achieve the above object, the present invention provides a perfluorosulfonic acid resin that does not contain perfluorooctanoic acid or perfluorooctane sulfonic acid, which is copolymerized by an emulsion method from monomers containing perfluorooxaolefin sulfonyl fluoride and a water-soluble perfluorooxaolefin sulfonate, wherein the perfluorooxaolefin sulfonate is obtained by hydrolyzing the perfluorooxaolefin sulfonyl fluoride with an alkali solution; the mass ratio of the perfluorooxaolefin sulfonyl fluoride to the perfluorooxaolefin sulfonate is (4-8):1.

[0005] In one embodiment, the perfluorooxaolefin sulfonyl fluoride is perfluoro 3,6-dioxa-4-methyl-7-octene sulfonyl fluoride (PSVE), and the perfluorooxaolefin sulfonate is perfluoro 3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R), wherein the chemical formula of perfluoro 3,6-dioxa-4-methyl-7-octene sulfonyl fluoride (PSVE) is

[0006]

[0007] The chemical formula of perfluoro-3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R) is

[0008] R is Li, Na, K or NH4.

[0009] In one embodiment, the monomer further includes other monomers: one or a combination of tetrafluoroethylene (TFE), perfluoro-2,2-dimethyl-1,3-dioxolane (PDD), hexafluoropropylene (HFP), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, vinyl fluoride (VF), vinylidene fluoride (VF2) and perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD).

[0010] In one embodiment, the mass ratio of the total mass of the other monomers and perfluorooxaolefin sulfonyl fluoride to the mass ratio of the perfluorooxaolefin sulfonate is no more than 15.

[0011] In one embodiment, the other monomer is tetrafluoroethylene (TFE), wherein the mass ratio of tetrafluoroethylene (TFE), perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate (PSVE-R) is (2-4):(4-8):1.

[0012] The present invention also provides a method for preparing the perfluorosulfonic acid resin as described above, which comprises the following steps: (1) adding perfluorooxaolefin sulfonyl fluoride and alkali solution into a reaction container, hydrolyzing to obtain a water-soluble perfluorooxaolefin sulfonate, and diluting with water to obtain an aqueous solution of the perfluorooxaolefin sulfonate; dissolving a water-soluble initiator in deionized water to obtain an initiator aqueous solution; (2) adding the perfluorooxaolefin sulfonate aqueous solution obtained in step (1) and a monomer of perfluorooxaolefin sulfonyl fluoride into a high-pressure polymerization kettle, heating and stirring, mixing evenly, and removing bubbles to obtain a primary mixed solution; 3) In the high-pressure polymerization kettle of step (2), nitrogen is purged and cleaned, and other monomers and the initiator aqueous solution of step (1) are added in sequence, and after being stirred evenly, the temperature is increased and the reaction temperature and time are controlled to obtain a perfluorosulfonic acid resin emulsion; (4) the stirring is stopped, the temperature is lowered to below 40° C., the pressure of the polymerization kettle is vented to normal pressure, the perfluorosulfonic acid resin emulsion in the kettle is taken out, demulsified and condensed, filtered, washed, devolatilized, and dried to obtain a powdered perfluorosulfonic acid resin; (5) the perfluorosulfonic acid resin of step (4) is hydrolyzed with alkaline solution and hydrogenated with acid solution to obtain a hydrogen-type perfluorosulfonic acid resin.

[0013] In one embodiment, the alkali solution is a solution of lithium hydroxide, sodium hydroxide or potassium hydroxide; the water-soluble initiator is one or a combination of persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylimidazoline and azobiscyanovaleric acid.

[0014] The present invention also provides a perfluorosulfonic acid resin as described above, wherein the melt index MFI of the perfluorosulfonic acid resin is 5.0@270°C / 3050g, and the exchange equivalent weight EW of the hydrogen perfluorosulfonic acid resin is 1423g / mol.

[0015] The present invention also provides a Pt / C catalyst layer prepared from the perfluorosulfonic acid resin as described above.

[0016] The present invention also provides a hydrogen fuel cell membrane electrode prepared using the Pt / C catalyst layer as described above.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The perfluorosulfonic acid resin and the preparation method thereof of the present invention do not require a complicated post-treatment process for removing the surfactant after polymerization.

[0019] (2) Perfluoroalkenesulfonate is a perfluoro surfactant containing double bonds, which can be used as an emulsifier and as an active polymerizable monomer to participate in the polymerization reaction; wherein the precursor for preparing perfluoroalkenesulfonate, perfluoroalkenesulfonyl fluoride, has a highly similar chemical structure to that of perfluoroalkenesulfonate, and when matched in a ratio within a specific numerical range, the emulsifier effect of perfluoroalkenesulfonate can be synergistically enhanced, and the activity of perfluoroalkenesulfonate in participating in the polymerization reaction can also be effectively improved; the combined use of perfluoroalkenesulfonyl fluoride and perfluoroalkenesulfonate does not change the structure of the perfluorosulfonic acid resin while omitting the post-treatment process after the resin synthesis.

[0020] (3) Compared with the resin without double bond emulsifier used in the prior art, the perfluorosulfonic acid resin of the present invention has higher purity and better proton conductivity, oxygen permeability, mechanical strength and durability.

[0021] (4) The raw materials of the present invention are commercial products and are easily available, and the conditions of the synthesis method are mild and controllable, which is easy to be commercialized on a large scale. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the invention more obvious and easy to understand, the specific embodiments of the invention are described in detail below.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] The perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid according to the present invention is copolymerized by an emulsion method with monomers containing perfluorooxaolefin sulfonyl fluoride and water-soluble perfluorooxaolefin sulfonate, wherein the perfluorooxaolefin sulfonate is obtained by hydrolyzing the perfluorooxaolefin sulfonyl fluoride with alkali solution; the mass ratio of perfluorooxaolefin sulfonyl fluoride to perfluorooxaolefin sulfonate is (4-8):1. Wherein, the perfluorooxaolefin sulfonyl fluoride is perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl fluoride (PSVE), and the perfluorooxaolefin sulfonate is perfluoro-3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R), wherein the chemical formula of perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl fluoride (PSVE) is

[0025]

[0026] The chemical formula of perfluoro-3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R) is

[0027] R is Li, Na, K or NH4.

[0028] In one embodiment, the monomer may also include other monomers: tetrafluoroethylene (TFE), perfluoro-2,2-dimethyl-1,3-dioxole (PDD), hexafluoropropylene (HFP), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, vinyl fluoride (VF), vinylidene fluoride (VF2) and perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD) One or a combination.

[0029] In one embodiment, the mass ratio of the total mass of the other monomers and perfluorooxaolefin sulfonyl fluoride to the mass ratio of the perfluorooxaolefin sulfonate is no more than 15.

[0030] In one embodiment, the other monomer may be tetrafluoroethylene (TFE), wherein the mass ratio of tetrafluoroethylene (TFE), perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate (PSVE-R) is (2-4):(4-8):1.

[0031] The preparation method of the perfluorosulfonic acid resin according to the present invention comprises the following steps: (1) adding perfluorooxaolefin sulfonyl fluoride and alkali solution into a reaction container, hydrolyzing to obtain a water-soluble perfluorooxaolefin sulfonate, and diluting with water to obtain an aqueous solution of the perfluorooxaolefin sulfonate; dissolving a water-soluble initiator in deionized water to obtain an initiator aqueous solution; (2) adding the perfluorooxaolefin sulfonate aqueous solution obtained in step (1) and the monomer of perfluorooxaolefin sulfonyl fluoride into a high-pressure polymerization reactor, heating and stirring, mixing evenly, and removing bubbles to obtain a primary mixed solution; (3) in step (2) The high-pressure polymerization kettle is cleaned by nitrogen purging, and other monomers and the initiator aqueous solution of step (1) are added in sequence, and after stirring evenly, the temperature is increased and the reaction temperature and time are controlled to obtain a perfluorosulfonic acid resin emulsion; (4) The stirring is stopped, the temperature is lowered to below 40° C., the pressure of the polymerization kettle is vented to normal pressure, the perfluorosulfonic acid resin emulsion in the kettle is taken out, and after demulsification and coagulation, filtering, washing, devolatilization, and drying, a powdered perfluorosulfonic acid resin is obtained; (5) The perfluorosulfonic acid resin of step (4) is hydrolyzed with alkaline solution and hydrogenated with acid solution to obtain a hydrogen-type perfluorosulfonic acid resin.

[0032] In one embodiment, the alkali solution may be a solution of lithium hydroxide, sodium hydroxide or potassium hydroxide; the water-soluble initiator is one or a combination of persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylimidazoline and azobiscyanovaleric acid.

[0033] The melt index MFI of the perfluorosulfonic acid resin according to the present invention is 5.0@270°C / 3050g, and the exchange equivalent weight EW of the hydrogen perfluorosulfonic acid resin is 1423g / mol.

[0034] The perfluorosulfonic acid resin according to the present invention can be used to prepare a Pt / C catalyst layer.

[0035] The Pt / C catalyst layer according to the present invention can be used to prepare a hydrogen fuel cell membrane electrode.

[0036] The following examples specifically illustrate the preparation method of the perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid, its products and applications. Main raw materials and equipment used: Unless otherwise specified, the raw materials and equipment of each embodiment and comparative example are the same; materials without specific models or types are purchased from the market or commonly available through common channels, and are not specifically limited.

[0037] Example 1

[0038] (1) adding 44.6 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and 240 g of a 1 wt % lithium hydroxide aqueous solution into a reaction vessel, stirring at room temperature until the perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) is completely dissolved to obtain water-soluble perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate lithium (PSVE-Li) containing polymerizable double bonds, and diluting with water to obtain a 1 wt % perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate lithium (PSVE-Li) aqueous solution; dissolving 1.25 g of ammonium persulfate in 100 ml of deionized water to obtain an ammonium persulfate aqueous solution;

[0039]

[0040] (2) 3 L of the perfluoro-3,6-dioxa-4-methyl-7-octenesulphonic acid lithium (PSVE-Li) aqueous solution obtained in step (1) was added into a 5 L stainless steel high pressure polymerization reactor, stirring was started and the temperature was raised to 60° C., 250 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulphonyl fluoride (PSVE) was added, and stirring was carried out for 0.5 hour at a stirring rate of 300 rpm;

[0041] (3) adding tetrafluoroethylene gas to the stainless steel high-pressure polymerization reactor of step (2) until the pressure inside the reactor reaches 2.4 MPa, adding the ammonium persulfate aqueous solution of step (1), and when the pressure inside the reactor begins to drop, adding tetrafluoroethylene gas and maintaining the pressure inside the reactor at 2.4 MPa until 150 g of tetrafluoroethylene is consumed;

[0042] (4) stopping stirring, cooling to below 40° C., venting the polymerization kettle to normal pressure, taking out the emulsion in the kettle, demulsifying and condensing with 20% nitric acid, filtering, washing, devolatilizing, and drying to obtain a powdered perfluorosulfonic acid resin;

[0043] (5) hydrolyzing the perfluorosulfonic acid resin in step (4) with alkaline solution and hydrogenating with acid solution to obtain a hydrogen-type perfluorosulfonic acid resin;

[0044] (6) 10 g of the hydrogenated perfluorosulfonic acid resin of step (5), 4 g of Pt / C catalyst and 30 g of deionized water were mixed evenly to obtain a slurry; the slurry was coated on the surface of the base film PET, and vacuum heated at 100°C and a vacuum degree of 0.5 MPa for 3 h, and cooled to room temperature to obtain a catalyst layer.

[0045] Example 2

[0046] (1) adding 40 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and 200 g of a 1 wt % sodium hydroxide aqueous solution into a reaction container, stirring at room temperature until the perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) is completely dissolved to obtain water-soluble perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate sodium (PSVE-Na) containing polymerizable double bonds, and diluting with water to obtain a 1 wt % perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate sodium (PSVE-Na) aqueous solution; dissolving 1.25 g of sodium persulfate in 100 ml of deionized water to obtain a sodium persulfate aqueous solution;

[0047] (2) 3 L of the aqueous solution of perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate sodium (PSVE-Na) obtained in step (1) was added into a 5 L stainless steel high-pressure polymerization reactor, stirring was started and the temperature was raised to 60° C., 160 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) was added, and stirring was carried out for 0.5 hour at a stirring rate of 300 rpm;

[0048] (3) adding tetrafluoroethylene gas to the stainless steel high-pressure polymerization reactor of step (2) until the pressure inside the reactor reaches 2.4 MPa, adding the sodium persulfate aqueous solution of step (1), and when the pressure inside the reactor begins to drop, adding tetrafluoroethylene gas and maintaining the pressure inside the reactor at 2.4 MPa until 80 g of tetrafluoroethylene is consumed;

[0049] (4) stopping stirring, cooling to below 40° C., venting the polymerization kettle to normal pressure, taking out the emulsion in the kettle, demulsifying and condensing with 20% nitric acid, filtering, washing, devolatilizing, and drying to obtain a powdered perfluorosulfonic acid resin;

[0050] (5) hydrolyzing the perfluorosulfonic acid resin in step (4) with alkaline solution and hydrogenating with acid solution to obtain a hydrogen-type perfluorosulfonic acid resin;

[0051] (6) 10 g of the hydrogenated perfluorosulfonic acid resin of step (5), 4 g of Pt / C catalyst and 30 g of deionized water were mixed evenly to obtain a slurry; the slurry was coated on the surface of the base film PET, and vacuum heated at 100°C and a vacuum degree of 0.5 MPa for 3 h, and cooled to room temperature to obtain a catalyst layer.

[0052] Example 3

[0053] (1) adding 40 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and 250 g of a 1 wt % potassium hydroxide aqueous solution into a reaction vessel, stirring at room temperature until the perfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) is completely dissolved to obtain water-soluble perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate potassium (PSVE-K) containing polymerizable double bonds, and diluting with water to obtain a 1 wt % perfluoro-3,6-dioxa-4-methyl-7-octenesulfonate potassium (PSVE-K) aqueous solution; dissolving 1.25 g of sodium persulfate in 100 ml of deionized water to obtain a potassium persulfate aqueous solution;

[0054] (2) 3 L of the potassium perfluoro-3,6-dioxa-4-methyl-7-octenesulphonate (PSVE-K) aqueous solution obtained in step (1) was added into a 5 L stainless steel high pressure polymerization reactor, stirring was started and the temperature was raised to 60° C., 320 g of perfluoro-3,6-dioxa-4-methyl-7-octenesulphonyl fluoride (PSVE) was added, and stirring was carried out for 0.5 hour at a stirring rate of 300 rpm;

[0055] (3) adding tetrafluoroethylene gas to the stainless steel high-pressure polymerization reactor of step (2) until the pressure inside the reactor reaches 2.4 MPa, adding the potassium persulfate aqueous solution of step (1), and when the pressure inside the reactor begins to drop, adding tetrafluoroethylene gas and maintaining the pressure inside the reactor at 2.4 MPa until 160 g of tetrafluoroethylene is consumed;

[0056] (4) stopping stirring, cooling to below 40° C., venting the polymerization kettle to normal pressure, taking out the emulsion in the kettle, demulsifying and condensing with 20% nitric acid, filtering, washing, devolatilizing, and drying to obtain a powdered perfluorosulfonic acid resin;

[0057] (5) hydrolyzing the perfluorosulfonic acid resin in step (4) with alkaline solution and hydrogenating with acid solution to obtain a hydrogen-type perfluorosulfonic acid resin;

[0058] (6) 10 g of the hydrogenated perfluorosulfonic acid resin of step (5), 4 g of Pt / C catalyst and 30 g of deionized water were mixed evenly to obtain a slurry; the slurry was coated on the surface of the base film PET, and vacuum heated at 100°C and a vacuum degree of 0.5 MPa for 3 h, and cooled to room temperature to obtain a catalyst layer.

[0059] Comparative Example 1

[0060] Except that PSVE-Li of the same mass completely replaced PSVE, the rest was the same as Example 1.

[0061] Comparative Example 2

[0062] Except that 5 g of sodium perfluorooctanoate replaced a portion of PSVE-Na of the same mass, everything else was the same as Example 2.

[0063] Performance Testing

[0064] 1. Test the yield, melt index MFI (270℃ / 3050g) and pollutant perfluorooctanoic acid content (GB / T31126-2014) of powdered perfluorosulfonic acid resin.

[0065] 2. Test the exchange equivalent EW value of hydrogen perfluorosulfonic acid resin (GB / T20042.32022); at 23°C and 0% relative humidity, use the instrument ( Minneapolis, MN, USA) tested the oxygen permeability of the catalyst layer after it was peeled off from the surface of the base membrane PET; at 80°C and 95% relative humidity, the catalyst layer was loaded into the electrolyte membrane of the electrochemical cell, the test electrodes were connected to both sides of the electrolyte membrane, an external voltage was applied, and the proton conductivity was calculated.

[0066] 3. Use a universal material testing machine to test the mechanical strength of the catalyst layer (GB / T20042.3-2022).

[0067] See Table 1 for specific data.

[0068] Table 1

[0069]

[0070] It can be seen from the data of the examples and comparative examples that the perfluorosulfonic acid resin prepared by the present invention does not contain emulsifiers such as perfluorooctanoic acid or perfluorooctanesulfonic acid, the yield of the preparation method is high, and the product has a suitable melt index; the catalyst layer prepared by using the perfluorosulfonic acid resin has good performance, and the retention rate of various properties after thermal aging is better than that of the perfluorosulfonic acid resin with residual perfluorooctanoic acid, and has good durability and heat resistance. At the same time, it is also proved that the residual emulsifier is one of the important factors affecting the performance of the perfluorosulfonic acid resin catalyst layer.

[0071] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid, characterized in that: The invention is prepared by copolymerizing monomers containing perfluorooxaolefin sulfonyl fluoride and water-soluble perfluorooxaolefin sulfonate through an emulsion method, wherein the perfluorooxaolefin sulfonate is obtained by hydrolyzing the perfluorooxaolefin sulfonyl fluoride with an alkali solution; and the mass ratio of the perfluorooxaolefin sulfonyl fluoride to the perfluorooxaolefin sulfonate is (4-8):

1.

2. The perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid according to claim 1, characterized in that: The perfluorooxaolefin sulfonyl fluoride is perfluoro 3,6-dioxa-4-methyl-7-octene sulfonyl fluoride (PSVE), and the perfluorooxaolefin sulfonate is perfluoro 3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R), wherein: The chemical formula of perfluoro-3,6-dioxa-4-methyl-7-octenesulphonyl fluoride (PSVE) is The chemical formula of perfluoro-3,6-dioxa-4-methyl-7-octene sulfonate (PSVE-R) is R is Li, Na, K or NH4.

3. The perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid according to claim 2, characterized in that: The monomers also include other monomers: one or a combination of tetrafluoroethylene (TFE), perfluoro-2,2-dimethyl-1,3-dioxolane (PDD), hexafluoropropylene (HFP), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, vinyl fluoride (VF), vinylidene fluoride (VF2) and perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD).

4. The perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid according to claim 3, characterized in that: The mass ratio of the total mass of the other monomers and perfluorooxaolefin sulfonyl fluoride to the mass ratio of the perfluorooxaolefin sulfonate is no more than 15.

5. The perfluorosulfonic acid resin containing no perfluorooctanoic acid or perfluorooctane sulfonic acid according to claim 3 or 4, characterized in that: The other monomer is tetrafluoroethylene (TFE), wherein the mass ratio of tetrafluoroethylene (TFE), perfluoro 3,6-dioxa-4-methyl-7-octenesulfonyl fluoride (PSVE) and perfluoro 3,6-dioxa-4-methyl-7-octenesulfonate (PSVE-R) is (2-4):(4-8):

1.

6. A method for preparing a perfluorosulfonic acid resin as claimed in any one of claims 1 to 5, characterized in that: The following steps are included: (1) adding perfluorooxaolefin sulfonyl fluoride and alkaline solution into a reaction vessel, hydrolyzing to obtain a water-soluble perfluorooxaolefin sulfonate, and diluting with water to obtain an aqueous solution of the perfluorooxaolefin sulfonate; dissolving a water-soluble initiator in deionized water to obtain an initiator aqueous solution; (2) adding the perfluorooxoolefin sulfonate aqueous solution obtained in step (1) and the monomer of perfluorooxoolefin sulfonyl fluoride into a high-pressure polymerization kettle, heating and stirring, mixing evenly, and removing bubbles to obtain a primary mixed solution; (3) in the high-pressure polymerization reactor of step (2), nitrogen is purged and cleaned, and other monomers and the initiator aqueous solution of step (1) are added in sequence, and after stirring evenly, the temperature is increased and the reaction temperature and time are controlled to obtain a perfluorosulfonic acid resin emulsion; (4) stopping stirring, cooling to below 40° C., venting the polymerization kettle to normal pressure, taking out the perfluorosulfonic acid resin emulsion in the kettle, demulsifying and condensing, filtering, washing, devolatilizing, and drying to obtain a powdered perfluorosulfonic acid resin; (5) The perfluorosulfonic acid resin of step (4) is hydrolyzed with alkaline solution and hydrogenated with acid solution to obtain hydrogen-type perfluorosulfonic acid resin.

7. The preparation method according to claim 6, characterized in that: The alkali solution is a solution of lithium hydroxide, sodium hydroxide or potassium hydroxide; the water-soluble initiator is one or a combination of persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylimidazoline and azobiscyanovaleric acid.

8. The perfluorosulfonic acid resin according to any one of claims 1 to 5 or the perfluorosulfonic acid resin obtained by the preparation method according to claim 6 or 7, characterized in that The melt index MFI of the perfluorosulfonic acid resin is 5.0@270°C / 3050g, and the exchange equivalent weight EW of the hydrogen perfluorosulfonic acid resin is 1423g / mol.

9. A Pt / C catalyst layer prepared from the perfluorosulfonic acid resin as claimed in claim 8.

10. A hydrogen fuel cell membrane electrode prepared using the Pt / C catalyst layer as claimed in claim 9.

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