A novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin and preparation method thereof, and perfluorosulfonic acid resin

Abstract

The present invention provides a novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin and a preparation method thereof, and a perfluorosulfonic acid resin, belonging to the technical field of perfluoro ion exchange membranes. The novel sulfonyl fluoride monomer is prepared by first synthesizing tetrafluorosulfone from tetrafluoroethylene and sulfur trioxide, and then synthesizing an addition product acyl fluoride from tetrafluorosulfone and hexafluoropropylene oxide, and then synthesizing a diaddition product acyl fluoride from the latter addition product and perfluoroepoxyisobutane, and the diaddition acyl fluoride reacts with carbonate to decarboxylate to generate fluorosulfonyl propenyl ether. The novel fluorosulfonyl propenyl ether monomer prepared by the present invention can be used to prepare a perfluorosulfonic acid resin with high stability.

Description

Technical Field

[0001] The invention belongs to the technical field of perfluoro ion exchange membranes, and specifically relates to a novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin and a preparation method thereof, and the perfluorosulfonic acid resin. Background Art

[0002] Perfluorosulfonic acid (PFSA) proton exchange membrane was first developed and commercialized by DuPont in the 1970s (Nafion series). Its structure includes a polytetrafluoroethylene-like main chain and a short side chain containing a sulfonic acid group. This structural feature makes the PFSA proton membrane have both high stability and high proton conductivity. Proton exchange membranes were first used in the chlor-alkali industry and proton exchange membrane fuel cells. The proton membrane divides the battery or electrolytic cell into a cathode chamber and an anode chamber, and ions can pass selectively. PFSA proton membrane technology is mature and has excellent performance. It is currently the most widely used proton exchange membrane system. Perfluorosulfonic acid ion exchange membranes have high current density at low temperatures; high conductivity at high humidity; strong chemical stability under common environments; low resistance during proton conduction, etc.; they have many advantages and are one of the important components of new energy batteries and electrolytic cells.

[0003] In addition to DuPont Nafion series products, Xus-B204 from Dow Chemical in the United States, Aquivion series from Solvay in Belgium, Aciplex series from Asahi Kasei in Japan, Flemion series from Asahi Glass in Japan, and DF series from Shandong Dongyue Group in my country all use PFSA as the base material.

[0004] The common molecular structure of perfluorosulfonic acid resin is as follows:

[0005]

[0006] Perfluorosulfonic acid resin is tetrafluoroethylene and fluorosulfonyl vinyl ether [CF2=CF(OCF2CFCF3) z O (CF2) n SO2F] monomer (sulfonyl fluoride monomer) copolymerization, the difference in the structure and side chain length of the sulfonyl fluoride monomer will lead to slightly different performance of perfluorosulfonic acid resin in application.

[0007] Sulfonyl fluoride monomer [CF2=CFO(CF2) n There are several main methods for preparing SO2F:

[0008] Asahi Glass patent JP2009167120A uses pentafluoro-3-bromo-1,2-epoxypropane as raw material, and generates CF2=CFOCF2CF2SO2F through addition and decarboxylation. Daikin patent JP2010235568A uses 1,3-dichloro-1,2,3,3-tetrafluoroepoxypropane as raw material, and generates CF2=CFOCF2CF2SO2F through addition and decarboxylation. Daikin patent WO2010114144A1 uses 1,1,3-trichloro-2,3,3-trifluoroepoxypropane as raw material, and generates CF2=CFOCF2CF2SO2F through addition and decarboxylation. DuPont patents US3301893 and US3560568 report the process of adding tetrafluorosulfone to hexafluoropropane oxide. Daikin patent CN101052616A reported that CF=CFOCF2CF2SO2Cl used potassium fluoride as an external fluorine source to obtain CF2=CFOCF2CF2SO2F. DuPont patent US6388139 reported that CF2ClCFClOCF2CF2SO2F was dechlorinated in the presence of zinc powder to obtain CF2=CFOCF2CF2SO2F. Shandong Dongyue Shenzhou New Materials Co., Ltd. patent CN101696178B reported the process of trifluorovinyl sulfate and tetrafluorosulfone reacting in the presence of catalysts (CsF, KF, HF) to generate CF2=CFOCF2CF2SO2F.

[0009] Developing new monomers to further improve the long-term stability and temperature resistance of perfluorosulfonic acid resins has become a new research direction in recent years. Summary of the invention

[0010] The present invention provides a novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin and a preparation method thereof. Compared with a traditional fluorosulfonyl vinyl ether monomer, the monomer can improve the long-term stability and temperature resistance of the prepared perfluorosulfonic acid resin without reducing the electrical conductivity.

[0011] One of the purposes of the present invention is to provide a novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin.

[0012] The second object of the present invention is to provide a method for preparing the novel sulfonyl fluoride monomer.

[0013] The third object of the present invention is to provide a perfluorosulfonic acid resin prepared from the novel sulfonyl fluoride monomer.

[0014] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0015] In a first aspect, the present invention provides a novel sulfonyl fluoride monomer for preparing perfluorosulfonic acid resin, having the following structural formula: CF2=C(CF3)-O-CF2CF(CF3)OCF2CF2-SO2F.

[0016] In a second aspect, the present invention provides a method for preparing the novel sulfonyl fluoride monomer, comprising the following steps:

[0017] S1, tetrafluorosulfone and hexafluoropropylene oxide are reacted to obtain an addition product;

[0018] S2, the monoaddition product and perfluoroisobutylene oxide are reacted to obtain a diaddition product;

[0019] S3, the diaddition product and carbonate are reacted by decarboxylation to obtain a novel sulfonyl fluoride monomer.

[0020] Further preferably, the preparation method further comprises:

[0021] Tetrafluorosulfone is synthesized from S0, tetrafluoroethylene and sulfur trioxide.

[0022] The following is a detailed description:

[0023] Step S0:

[0024] In some implementations, step S0 specifically includes:

[0025] 100-350 parts by mass of tetrafluorosulfone and 50-80 parts by mass of sulfur trioxide are placed in a reaction kettle and stirring and cooling of the refrigerant are started to allow the sulfur trioxide to fully dissolve in the tetrafluorosulfone (on the one hand, it acts as a solvent to dissolve SO3, and on the other hand, it adjusts the reaction speed to prevent the reaction speed from being too fast). Then, an excess of 110-130 parts by mass of gaseous tetrafluoroethylene is slowly introduced into the reaction kettle for reaction. When the sulfur trioxide is completely converted into tetrafluorosulfone, the reaction is stopped.

[0026]

[0027] Preferably, the refrigerant temperature is -40°C to -35°C;

[0028] Preferably, the reaction temperature is controlled not to exceed 5°C and stirred for 2-3 hours.

[0029] Step S1:

[0030] In some implementations, step S1 specifically includes:

[0031] First, 20-30 parts by weight of an organic solvent is added to a reactor, then 2-4 parts by weight of a catalyst and 80-100 parts by weight of tetrafluorosultone are added, stirring and cooling of the refrigerant are started, and then 100-120 parts by weight of hexafluoropropylene oxide are slowly introduced in batches under the premise of controlling the reaction temperature to obtain an acyl fluoride monoaddition product of sultone and hexafluoropropylene oxide.

[0032]

[0033] Preferably, the organic solvent is one selected from ethylene glycol diethyl ether and diethylene glycol dimethyl ether.

[0034] Preferably, the catalyst is one selected from CsF or KF.

[0035] Preferably, the stirring speed is 200-500 rpm; the refrigerant temperature is -40°C to -35°C.

[0036] Preferably, hexafluoropropylene oxide is slowly introduced after stirring for 1-2 hours.

[0037] Preferably, the reaction temperature is -5 to 0°C, and the reaction time is 1 to 2 hours.

[0038] Step S2:

[0039] In some implementations, step S2 specifically includes:

[0040] In the same reactor as in step S1, the same reaction conditions are controlled, and 130-160 parts of perfluoroisobutylene oxide (octafluoroisobutylene oxide, perfluoromethylpropylene oxide) are continuously added to allow the acyl fluoride monoaddition product of sultone and hexafluoropropylene oxide to further react with perfluoroisobutylene oxide, and a new diaddition product is obtained after fractional distillation and purification.

[0041]

[0042] Preferably, the fractionation purification specifically comprises: placing the reaction product in a laboratory distillation tower, heating the reaction product to 90-120°C under reduced pressure (pressure controlled at -40 to -80 kPa), and after 3-4 hours of total reflux, separating and purifying the components with different boiling points at different tower top temperatures under a controlled reflux ratio of 5:1-10:1 according to the difference in boiling points of the mono-addition product, the di-addition product and the by-product, to obtain a di-addition product with a purity ≥95%.

[0043] Step S3:

[0044] In some implementations, step S3 specifically includes:

[0045] The diaddition product is vaporized in a vaporizer at 200-250° C. and then decarboxylated with carbonate at 200-210° C. in a decarboxylation reactor. The reaction gas is collected, condensed, and purified to obtain the target acyl fluoride.

[0046]

[0047] Preferably, the carbonate is one or more selected from Na2CO3 and K2CO3.

[0048] Preferably, purification specifically comprises:

[0049] The decarboxylation reaction product is placed in a laboratory distillation tower, and the product is heated to 100-120°C under reduced pressure (pressure controlled at -60 to -80 kPa). After 3-4 hours of total reflux, different boiling point components are separated and purified at different tower top temperatures under a reflux ratio of 4:1-8:1 according to the boiling point difference of acryloyl fluoride and by-products to obtain a reaction product with a purity of ≥98%.

[0050] The ether carbon of the sulfonyl fluoride monomer prepared by the present invention is connected with a trifluoromethyl group, while the conventional one is fluorine, as shown below:

[0051]

[0052] In a third aspect, the present invention provides a perfluorosulfonic acid resin prepared from the above-mentioned novel sulfonyl fluoride monomer.

[0053] In some embodiments, the method for preparing a perfluorosulfonic acid resin comprises:

[0054] Water, 900-1200 parts by weight of the sulfonyl fluoride monomer, and 100-130 parts by weight of an emulsifier (such as ammonium perfluorooctanoate) are mixed and stirred, and then the system is heated to 80-85° C., and 3000-3800 parts by weight of tetrafluoroethylene are continuously introduced until the pressure reaches 1.5-2 MPa; 45-60 parts by weight of an initiator (such as potassium persulfate) are quickly added, and tetrafluoroethylene is continuously introduced to maintain the pressure in the kettle to obtain a perfluorosulfonic acid ion exchange resin, and after condensation, water washing, and drying, a dry perfluorosulfonic acid resin is obtained.

[0055] Beneficial effects:

[0056] After the sulfonyl fluoride monomer of the present invention is polymerized with the tetrafluoroethylene monomer, a carbon fluorine methyl bond is connected to the carbon linked to the ether group. Compared with the traditional connection of a fluorine atom, the entire skeleton structure can be improved, and the prepared perfluorosulfonic acid resin has better long-term stability and temperature resistance without reducing the conductivity.

[0057] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0059] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0060] Tetrafluorosulfone was from Shandong Huafu Chemical Co., Ltd.;

[0061] Sulfur trioxide came from Anhui Huaertai Co., Ltd.;

[0062] Tetrafluoroethylene was from Shaowu Yonghe Jintang New Materials Co., Ltd.;

[0063] Ethylene glycol diethyl ether was from Sinopharm Reagent Company;

[0064] Hexafluoropropylene oxide was from Fujian Huayi Sanai Fuyou New Materials Co., Ltd.;

[0065] Perfluoroisobutane epoxy comes from Sinochem Blue Sky Fluoro Materials Co., Ltd.

[0066] Example 1

[0067] The preparation method of sulfonyl fluoride monomer CF2=C(CF3)-O-CF2CF(CF3)OCF2CF2-SO2F comprises the following steps:

[0068] 1. First, vacuumize the 5L reactor lined with PTFE connected to the vacuum and nitrogen pipelines, quickly inhale about 1000g of tetrafluorosulfone and 800g of liquid sulfur trioxide into the reactor, start stirring and start the cooling refrigerant (-35℃ refrigerant) of the reactor to fully dissolve it in tetrafluorosulfone, slowly introduce a slightly excessive amount of about 1200g of tetrafluoroethylene, control the reaction temperature not to exceed 5℃, stop the reaction after stirring for 2 hours, reduce the temperature in the kettle to about -30℃ to release the residual pressure in the kettle, and obtain tetrafluorosulfone;

[0069] 2. In another 5L reactor, first evacuate the reactor, and after the vacuum degree reaches -0.095MPa, use the vacuum negative pressure to inhale about 300g of ethylene glycol diethyl ether, then add 30g of CsF as a reaction catalyst, and quickly evacuate to -0.090MPa again, inhale about 1000g of tetrafluorosulfone, start the stirring speed and control it at 300rpm, and pass -35℃ into the jacket for cooling. After stirring for 1 hour, slowly pass 1100g of hexafluoropropylene oxide in batches, and the reaction temperature is controlled at 0℃ or below. After the hexafluoropropylene oxide is added, continue to stir and react for 1 hour;

[0070] 3. Then, 1300 parts of perfluorobutylene oxide are slowly introduced into the 5L reactor, the reaction temperature is controlled below 0°C, and the stirring reaction is continued for 2 hours after the addition of the fully fluorobutylene oxide. The reaction product is then placed in a laboratory fractionation tower after passing through a small laboratory fractionation tower. The reaction product is heated to 90-120°C under reduced pressure (the pressure is controlled at -40 to -80 kPa). After 3-4 hours of total reflux, different boiling point components are separated and purified at different tower top temperatures according to the boiling point differences of the mono-addition product, the di-addition product and the by-products, and the reflux ratio is controlled to be 5:1-10:1 to obtain a di-addition product with a purity of ≥95%;

[0071] 4. Add 3kg K2CO3 to the fluidized bed reactor, heat the K2CO3 in the fluidized bed to 200°C by heating the heat-conducting oil in the jacket, heat the vaporizer connected to the fluidized bed to 210°C, slowly add the diaddition product to vaporize it, and then introduce it into the fluidized bed reactor in a small amount of nitrogen atmosphere, so that the diaddition product and K2CO3 undergo a gas-solid reaction, collect the reaction gas obtained by the reaction at the top and collect it as the final reaction product after passing through a condenser; then pass through a laboratory small distillation tower, put the decarboxylation reaction product into the laboratory distillation tower, heat the product to 100-120°C under reduced pressure (pressure controlled at -60 to -80kPa), and after 3-4 hours of total reflux, according to the difference in boiling points of acrylamide fluoride and by-products, separate and purify different boiling point components at different tower top temperatures under a reflux ratio of 4:1-8:1 to obtain a reaction product with a purity of 98%.

[0072] Statistics of conversion rate and purity of each reaction step

[0073]

[0074] Example 2

[0075] Example 2 is basically the same as Example 1, except that diethylene glycol dimethyl ether is used as solvent in the addition reaction of step 2, and cheaper Na2CO3 is used as decarboxylation salt in the decarboxylation process of step 4.

[0076] Comparative Example

[0077] CF2=CFO-CF2CF(CF3)OCF2CF2-SO2F, commercially available from Sigma Reagent Company with a purity of up to 99%, is used to produce PSVE monomer.

[0078] Test Case

[0079] The perfluorosulfonic acid resin was prepared using the sulfonyl fluoride monomers of the examples and comparative examples. The specific preparation process is as follows:

[0080] In a 100L steel polymerization kettle, add 50L ultrapure water, 1kg of sulfonyl fluoride monomer, and 120g of emulsifier ammonium perfluorooctanoate, perform nitrogen extraction in the kettle, and detect the oxygen content. If the content is reduced to below 20ppm, it is qualified. After stirring at 300rpm for half an hour, raise the temperature of the system to 80℃, and continuously introduce 3.5kg of tetrafluoroethylene into the kettle until the pressure reaches 1.5MPa; quickly add 50g of initiator potassium persulfate at 80℃, and continuously introduce tetrafluoroethylene to maintain the pressure in the kettle for 2h to obtain perfluorosulfonic acid ion exchange resin; after the pressure is maintained, stop the reaction, cool the reaction device to room temperature of 23℃, use nitrogen to replace the remaining gaseous tetrafluoroethylene monomer in the kettle to normal pressure, open the reactor to take out the polymer material, add 10% nitric acid to condense and filter to obtain the polymer material, wash it 3 times with 50-100L water, and use an oven at 200℃ to dry for 4h to obtain dry perfluorosulfonic acid resin.

[0081] The prepared perfluorosulfonic acid resin was tested as follows:

[0082] Conductivity / Exchange capacity: The ion exchange equivalent (EW) of the resin is determined in accordance with GB / T 20042.3. The reciprocal of the ion exchange equivalent is the exchange capacity (IEC).

[0083] Stability: Take 1 g to 2 g of a sample with uniform particle size and place it in an oven at (105±2)℃ for 3 h. Then place the sample in a desiccator and cool it to room temperature. Weigh 10 mg to 15 mg of the sample into a platinum crucible and determine the initial thermal decomposition temperature of the sample according to the method specified in GB / T 33047.1.

[0084] The results are shown in the following table.

[0085]

[0086] As shown in the results, the perfluorosulfonic acid resin prepared by using the propenyl ether of the present invention is close to the perfluorosulfonic acid resin prepared by using the conventional vinyl ether PSVE monomer for preparing Nafion in terms of exchange equivalent, but has a significantly higher initial thermal decomposition temperature.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A sulfonyl fluoride monomer for preparing a perfluorosulfonic acid resin, characterized in that: It has the following structural formula: CF2=C(CF3)-O-CF2CF(CF3)OCF2CF2-SO2F.

2. A method for preparing the sulfonyl fluoride monomer according to claim 1, characterized in that: The following steps are involved: S1, tetrafluorosulfone and hexafluoropropylene oxide are reacted to obtain an addition product ; S2, the monoaddition product and perfluorobutylene oxide are reacted to obtain the diaddition product ; S3. The diaddition product and carbonate are reacted by decarboxylation to obtain sulfonyl fluoride monomer.

3. The preparation method according to claim 2, characterized in that: The preparation method further comprises: Tetrafluorosulfone is synthesized from S0, tetrafluoroethylene and sulfur trioxide.

4. The preparation method according to claim 3, characterized in that: Step S0 specifically includes: 100-350 parts by weight of tetrafluorosulfone and 50-80 parts by weight of sulfur trioxide are placed in a reaction kettle and stirring and cooling of the refrigerant are started to fully dissolve the sulfur trioxide in the tetrafluorosulfone. Then, an excess of 110-130 parts by weight of gaseous tetrafluoroethylene is slowly introduced into the reaction kettle for reaction. When all the sulfur trioxide is converted into tetrafluorosulfone, the reaction is stopped.

5. The preparation method according to claim 4, characterized in that: The refrigerant temperature is -40℃~-35℃; the reaction temperature is controlled not to exceed 5℃, and stirred for 2-3 hours.

6. The preparation method according to claim 2, characterized in that: Step S1 specifically includes: First, add 20-30 parts by weight of an organic solvent into a reactor, then add 2-4 parts by weight of a catalyst and 80-100 parts by weight of tetrafluorosultone, start stirring and cooling the refrigerant, and then slowly introduce 100-120 parts by weight of hexafluoropropylene oxide in batches to react, so as to obtain an acyl fluoride monoaddition product of sultone and hexafluoropropylene oxide.

7. The preparation method according to claim 6, characterized in that: The organic solvent is one selected from ethylene glycol diethyl ether and diethylene glycol dimethyl ether; The catalyst is one selected from CsF or KF; The stirring speed is 200-500rpm; the refrigerant temperature is -40℃~-35℃; The reaction temperature is -5~0℃ and the reaction time is 1-2 hours.

8. The preparation method according to claim 2, characterized in that: Step S2 specifically includes: In the same reactor as in step S1, the same reaction conditions are controlled, and 130-160 parts of perfluoroisobutylene oxide are continuously added to further react the mono-addition product of sultone and hexafluoropropylene oxide with perfluoroisobutylene oxide, and a new di-addition product is obtained after fractional distillation and purification.

9. The preparation method according to claim 2, characterized in that: Step S3 specifically includes: The diaddition product is vaporized in a vaporizer at 200-250° C. and then decarboxylated with carbonate at 200-210° C. in a decarboxylation reactor. The reaction gas is collected, condensed, and purified to obtain a sulfonyl fluoride monomer.

10. A perfluorosulfonic acid resin, characterized in that The sulfonyl fluoride monomer is prepared from the sulfonyl fluoride monomer according to claim 1 or the sulfonyl fluoride monomer prepared by the preparation method according to any one of claims 2 to 9.

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