A process for the preparation of an aqueous dispersion of a perfluorinated sulfonic acid resin

Abstract

This invention discloses a method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion. The method involves: placing solid perfluorosulfonic acid resin in a high-pressure reactor, using water as a solvent, and dissolving it under high temperature and pressure for 4–20 hours under inert gas protection to obtain a perfluorosulfonic acid resin aqueous dispersion; placing the perfluorosulfonic acid resin aqueous dispersion in a glass reactor, mixing it with an organic solvent, and reacting it under certain temperature conditions for 2–8 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion with uniformly dispersed molecular chains after secondary dispersion. Using this invention, the process is simple, time-efficient, and suitable for industrialization. The prepared perfluorosulfonic acid resin alcohol aqueous dispersion has a moderate particle size and uniformly dispersed molecular chains, making it suitable for proton exchange membrane coating processes, and thus enabling the preparation of composite proton exchange membranes with excellent mechanical and electrochemical properties.

Description

Technical Field

[0001] This invention belongs to the field of proton exchange membrane preparation and relates to a method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion. The perfluorosulfonic acid resin alcohol aqueous dispersion prepared by this invention has uniformly dispersed molecular chains and excellent performance, making it suitable for proton membrane coating processes and further applicable to the preparation of proton exchange membrane hydrogen fuel cells. Background Technology

[0002] Since the beginning of the 21st century, with continuous technological advancements, people's demand for energy has been increasing, and the problem of fossil fuel scarcity has become increasingly serious. Countries around the world have shifted their technological focus to the development of new energy sources. Hydrogen energy, due to its cleanliness, efficiency, and excellent storage and transportation performance, has received widespread attention and is hailed as the ultimate energy source of the 21st century. Proton exchange membrane hydrogen fuel cells are clean and efficient electrochemical power generation devices with low operating temperatures and high specific power, showing great promise for applications in industries such as mobile power supplies and automobiles.

[0003] Perfluorosulfonic acid resin dispersions are key materials for the preparation of proton exchange membrane hydrogen fuel cells. The wettability of the solvent in the solution to porous polytetrafluoroethylene (PTFE), as well as the particle size and dispersion state of the resin molecules, have a significant impact on the performance of the prepared proton exchange membrane. Currently available commercially available perfluorosulfonic acid resin dispersions cannot meet the requirements for the preparation of composite proton exchange membranes based on porous PTFE. Therefore, to develop perfluorosulfonic acid resin dispersions suitable for the preparation of composite proton exchange membranes, researchers have conducted extensive research on the preparation methods of perfluorosulfonic acid resin solutions. In existing technologies, the preparation methods of perfluorosulfonic acid resin dispersions mostly involve directly dissolving the solid perfluorosulfonic acid resin in an organic solvent under certain temperature and pressure conditions (see CN103146001A, a method for preparing a perfluorosulfonic acid resin dispersion with uniformly dispersed molecular chains, and CN104140542A, a method for preparing a perfluorosulfonic acid resin dispersion). However, this process generates impurities such as ethers produced by the dehydroxylation of organic solvents, requiring subsequent liquid-liquid separation to obtain a clear perfluorosulfonic acid resin dispersion. This process is time-consuming, complex, and the performance of the perfluorosulfonic acid resin dispersion cannot be guaranteed. Therefore, there is a need to develop a low-cost, time-efficient, simple method for preparing a perfluorosulfonic acid resin dispersion with uniformly dispersed molecular chains. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing methods for preparing perfluorosulfonic acid resin dispersions, such as the easy generation of impurities like ethers and the complex post-dissolution processing, and to provide a method for preparing a perfluorosulfonic acid resin alcohol-aqueous dispersion. The method of this invention is characterized by its simple process, short processing time, and suitability for industrialization. The prepared perfluorosulfonic acid resin alcohol-aqueous dispersion has a moderate particle size and uniformly dispersed molecular chains. When preparing composite proton exchange membranes based on e-PTFE (expanded polytetrafluoroethylene), it exhibits good wetting effect on PTFE, promoting better bonding between resin molecules and the matrix, thereby producing composite proton exchange membranes with excellent mechanical and electrochemical properties.

[0005] The present invention relates to a method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, characterized by comprising the following steps:

[0006] a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir and dissolve it under high temperature and high pressure for 4 to 20 hours under the protection of inert gas to obtain an aqueous dispersion of perfluorosulfonic acid resin.

[0007] b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a certain temperature for 2 to 8 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion (after secondary dispersion to obtain a uniformly dispersed molecular chain).

[0008] In this invention, the perfluorosulfonic acid resin solid described in step a has a polytetrafluoroethylene structure (-CF2-CF2-) as its main chain, and -[OCF2C(CF3)F] as its main chain. m -O[CF2CF2]n-SO3H is composed of side chains, where m = 0 or 1, and n = 1 or 2.

[0009] In this invention: the perfluorosulfonic acid resin solid mentioned in step a can be from DuPont, USA. NR50, Solvay (Chemicals) Shanghai Co., Ltd. PW-79S, Asahi Glass of Japan Any one or more mixtures of F-9010.

[0010] In this invention, the perfluorosulfonic acid resin solid content in step a is 5% to 30% by weight (i.e., after the perfluorosulfonic acid resin solid is mixed with solvent water, the perfluorosulfonic acid resin solid content therein is 5% to 30% by weight).

[0011] In this invention, the inert gas mentioned in step a can be any one or a mixture of two or more of nitrogen, helium, and argon.

[0012] In the present invention, the high-temperature and high-pressure stirring and dissolving for 4 to 20 hours in step a refers to stirring and dissolving for 4 to 20 hours under the conditions of a reaction temperature of 100 to 300°C and a pressure of 1 to 10 MPa.

[0013] In this invention: the organic solvent mentioned in step b is any one or a mixture of two or more of ethanol, n-propanol, isopropanol, propylene glycol, glycerol, and n-butanol, and the weight percentage content of the organic solvent is 20% to 60% (that is: in the mixture of perfluorosulfonic acid resin aqueous dispersion and organic solvent obtained in step a, the weight percentage content of the organic solvent is 20% to 60%).

[0014] In the present invention, the reaction for 2 to 8 hours under certain temperature conditions mentioned in step b refers to the reaction for 2 to 8 hours under reaction temperature conditions of 20 to 120°C.

[0015] Compared with the prior art, the present invention has the following features and beneficial effects:

[0016] (1) In this invention, water is used as the solvent to dissolve the solid perfluorosulfonic acid resin under high temperature and high pressure to obtain a perfluorosulfonic acid resin aqueous dispersion. No impurities such as ether compounds are generated during the preparation process, and no separation treatment is required. Then, by adding an organic solvent to the perfluorosulfonic acid resin aqueous dispersion for secondary dispersion, the viscosity, particle size and dispersion degree of the perfluorosulfonic acid resin solution can be controlled simply and efficiently.

[0017] (2) By using the present invention, a perfluorosulfonic acid resin alcohol aqueous dispersion with a particle size between 50-300nm, a viscosity between 100-1000, uniform molecular chain dispersion, and controllable viscosity can be obtained through secondary dispersion.

[0018] (3) Using the present invention, water is used as a solvent to dissolve the solid perfluorosulfonic acid resin to obtain a perfluorosulfonic acid resin aqueous dispersion. Then, the perfluorosulfonic acid resin aqueous dispersion is further dispersed by an organic solvent to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion with a moderate particle size and uniform molecular chain dispersion. The method is simple and efficient. The preparation method of the perfluorosulfonic acid resin alcohol aqueous dispersion of the present invention can meet the manufacturing process of composite proton exchange membranes based on e-PTFE, and has important significance in realizing the industrialization of proton exchange membranes and improving their performance.

[0019] (4) The product of this invention has a simple preparation process, simple procedures, is easy to operate, and is highly practical. Attached Figure Description

[0020] Figure 1 This is a graph showing the particle size data of the perfluorosulfonic acid resin alcohol-aqueous dispersion obtained in Example 1, obtained through dynamic light scattering testing.

[0021] Figure 2This is a graph showing the particle size data of the perfluorosulfonic acid resin alcohol-water dispersion obtained in Example 2, obtained from dynamic light scattering testing. Detailed Implementation

[0022] The embodiments given below are intended to further illustrate the present invention, but should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0023] Example 1:

[0024] A method for preparing a perfluorosulfonic acid resin alcohol-aqueous dispersion, comprising the following steps: 120g of perfluorosulfonic acid resin solid (from DuPont, USA) is added... NR50 and 680g of water were placed in a high-temperature, high-pressure reactor. After purging the reactor with nitrogen, the mixture was heated to 180°C at a reaction pressure of 2MPa. The mixture was stirred and reacted for 8 hours to obtain an aqueous dispersion of perfluorosulfonic acid resin. Then, 960g of isopropanol and 640g of ethanol were added to the aqueous dispersion, and the mixture was stirred and reacted at 50°C for 3 hours to obtain a uniformly dispersed aqueous dispersion of perfluorosulfonic acid resin with a particle size between 50-250nm (particle size distribution is shown in the appendix). Figure 1 ).

[0025] Example 2:

[0026] A method for preparing a perfluorosulfonic acid resin alcohol-aqueous dispersion, comprising the following steps: 150g of perfluorosulfonic acid resin solid (from Solvay (Chemicals) Shanghai Co., Ltd.) PW-79S and 600g of water were placed in a high-temperature, high-pressure reactor. After purging the reactor with nitrogen, the mixture was heated to 230°C at a reaction pressure of 4MPa. The mixture was stirred and reacted for 12 hours to obtain an aqueous dispersion of perfluorosulfonic acid resin. Then, 400g of propylene glycol and 350g of ethanol were added to the aqueous dispersion, and the mixture was stirred and reacted at 70°C for 5 hours to obtain a uniformly dispersed aqueous dispersion of perfluorosulfonic acid resin with a particle size between 50-250nm (particle size distribution is shown in the appendix). Figure 2 ).

[0027] Example 3:

[0028] A method for preparing a perfluorosulfonic acid resin alcohol-aqueous dispersion, comprising the following steps: 200g of perfluorosulfonic acid resin solid (from Asahi Glass, Japan) is added to an aqueous solution... F-9010 and 600g of water were placed in a high-temperature, high-pressure reactor. After purging the reactor with nitrogen, the mixture was heated to 240°C and the reaction pressure was 5MPa. Under these conditions, the mixture was stirred and reacted for 24 hours to obtain an aqueous dispersion of perfluorosulfonic acid resin. Then, 200g of propylene glycol and 100g of ethanol were added to the aqueous dispersion of perfluorosulfonic acid resin, and the mixture was stirred and reacted at 40°C for 8 hours to obtain an alcoholic aqueous dispersion of perfluorosulfonic acid resin with uniformly dispersed molecular chains.

[0029] Example 4:

[0030] A method for preparing a perfluorosulfonic acid resin alcohol-aqueous dispersion, comprising the following steps: 100g of perfluorosulfonic acid resin solid (from DuPont, USA) is added to an aqueous solution... NR50 and 400g of water were placed in a high-temperature, high-pressure reactor. After purging the reactor with nitrogen, the mixture was heated to 240°C and the reaction pressure was 5MPa. Under these conditions, the mixture was stirred and reacted for 48 hours to obtain an aqueous dispersion of perfluorosulfonic acid resin. Then, 400g of n-propanol and 100g of ethanol were added to the aqueous dispersion of perfluorosulfonic acid resin, and the mixture was stirred and reacted at 60°C for 12 hours to obtain an alcoholic aqueous dispersion of perfluorosulfonic acid resin with uniformly dispersed molecular chains.

[0031] Example 5:

[0032] A method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, comprising the following steps:

[0033] a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir and dissolve it under high temperature and high pressure for 4 hours under the protection of inert gas to obtain an aqueous dispersion of perfluorosulfonic acid resin.

[0034] The perfluorosulfonic acid resin solid has a weight percentage content of 5% (i.e., after the perfluorosulfonic acid resin solid is mixed with the solvent water, the weight percentage content of the perfluorosulfonic acid resin solid is 5%).

[0035] The high-temperature and high-pressure stirring and dissolution for 4 hours refers to stirring and dissolving for 4 hours under the conditions of a reaction temperature of 100℃ and a pressure of 1MPa.

[0036] b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a certain temperature for 2 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion (after secondary dispersion to obtain a uniformly dispersed molecular chain).

[0037] The organic solvent has a weight percentage content of 20% (i.e., the organic solvent has a weight percentage content of 20% in the mixture of the perfluorosulfonic acid resin aqueous dispersion obtained in step a and the organic solvent).

[0038] The aforementioned reaction at a certain temperature for 2 hours refers to a reaction at a temperature of 120℃ for 2 hours.

[0039] Example 6:

[0040] A method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, comprising the following steps:

[0041] a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir and dissolve it under high temperature and high pressure for 20 hours under the protection of inert gas to obtain an aqueous dispersion of perfluorosulfonic acid resin.

[0042] The perfluorosulfonic acid resin solid has a weight percentage content of 30% (that is, after the perfluorosulfonic acid resin solid is mixed with the solvent water, the weight percentage content of the perfluorosulfonic acid resin solid is 30%).

[0043] The high-temperature and high-pressure stirring and dissolution for 20 hours refers to stirring and dissolving for 20 hours under reaction conditions of 300℃ and 10MPa.

[0044] b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a certain temperature for 8 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion (with uniform molecular chain dispersion obtained through secondary dispersion).

[0045] The organic solvent has a weight percentage content of 60% (i.e., the organic solvent has a weight percentage content of 60% in the mixture of the perfluorosulfonic acid resin aqueous dispersion obtained in step a and the organic solvent).

[0046] The 8-hour reaction under certain temperature conditions refers to a reaction at a temperature of 20°C for 8 hours.

[0047] Example 7:

[0048] A method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, comprising the following steps:

[0049] a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir and dissolve it under high temperature and high pressure for 12 hours under the protection of inert gas to obtain an aqueous dispersion of perfluorosulfonic acid resin.

[0050] The perfluorosulfonic acid resin solid has a weight percentage content of 18% (that is, after the perfluorosulfonic acid resin solid is mixed with the solvent water, the weight percentage content of the perfluorosulfonic acid resin solid therein is 18%).

[0051] The high-temperature and high-pressure stirring and dissolution for 12 hours refers to stirring and dissolving for 12 hours under the conditions of a reaction temperature of 150℃ and a pressure of 5MPa.

[0052] b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a certain temperature for 5 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion (after secondary dispersion to obtain a uniformly dispersed molecular chain).

[0053] The organic solvent has a weight percentage content of 40% (i.e., the organic solvent has a weight percentage content of 40% in the mixture of the perfluorosulfonic acid resin aqueous dispersion obtained in step a and the organic solvent).

[0054] The aforementioned reaction at a certain temperature for 5 hours refers to a reaction at a temperature of 70°C for 5 hours.

[0055] Example 8:

[0056] A method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, comprising the following steps:

[0057] a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir and dissolve it under high temperature and high pressure for 6 hours under the protection of inert gas to obtain an aqueous dispersion of perfluorosulfonic acid resin.

[0058] The perfluorosulfonic acid resin solid has a weight percentage content of 10% (i.e., after the perfluorosulfonic acid resin solid is mixed with the solvent water, the weight percentage content of the perfluorosulfonic acid resin solid is 10%).

[0059] The high-temperature and high-pressure stirring and dissolution for 6 hours refers to stirring and dissolving for 6 hours under the conditions of a reaction temperature of 180℃ and a pressure of 3MPa.

[0060] b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a certain temperature for 3 hours to obtain a perfluorosulfonic acid resin alcohol aqueous dispersion (after secondary dispersion to obtain a uniformly dispersed molecular chain).

[0061] The organic solvent has a weight percentage content of 30% (i.e., the organic solvent has a weight percentage content of 30% in the mixture of the perfluorosulfonic acid resin aqueous dispersion obtained in step a and the organic solvent).

[0062] The aforementioned reaction at a certain temperature for 3 hours refers to a reaction at a temperature of 100℃ for 3 hours.

[0063] In the above embodiments 5-8:

[0064] The inert gas mentioned in step a is any one or a mixture of two or more of nitrogen, helium, and argon;

[0065] The organic solvent mentioned in step b is any one or a mixture of two or more of ethanol, n-propanol, isopropanol, propylene glycol, glycerol, and n-butanol;

[0066] The perfluorosulfonic acid resin solid mentioned in step a is from DuPont, USA. NR50, Solvay (Chemicals) Shanghai Co., Ltd. PW-79S, Asahi Glass of Japan Any one or more mixtures of F-9010.

[0067] The perfluorosulfonic acid resin solid mentioned in step a can also have a polytetrafluoroethylene structure (-CF2-CF2-) as the main chain, -[OCF2C(CF3)F] m -O[CF2CF2]n-SO3H is a compound with side chains, where m = 0 or 1, and n = 1 or 2.

[0068] As demonstrated in the above examples, dissolving solid perfluorosulfonic acid resin in water to obtain an aqueous dispersion of perfluorosulfonic acid resin, followed by secondary dispersion of the aqueous dispersion in an organic solvent, yields an alcoholic aqueous dispersion of perfluorosulfonic acid resin with moderate particle size and uniformly dispersed molecular chains. This method is simple and efficient. The preparation method of the perfluorosulfonic acid resin dispersion proposed in this invention can meet the requirements of the manufacturing process of composite proton exchange membranes based on e-PTFE, and is of great significance in realizing the industrialization of proton exchange membranes and improving their performance.

[0069] In the above embodiments: unless otherwise specified, the percentages used are weight (mass) percentages or percentages known to those skilled in the art; unless otherwise specified, the proportions used are weight (mass) proportions; the weight parts can all be grams or kilograms.

[0070] In the above embodiments, the process parameters (temperature, time, concentration, etc.) and the dosage values ​​of each component in each step are ranges, and any point can be applied.

[0071] The technical contents of this invention and the above embodiments that are not specifically described are the same as those of the prior art, and the raw materials are all commercially available products.

[0072] The present invention is not limited to the above embodiments; all embodiments described herein can be implemented and have the aforementioned good effects.

Claims

1. A method for preparing a perfluorosulfonic acid resin alcohol aqueous dispersion, characterized in that: Includes the following steps: a. Place the solid perfluorosulfonic acid resin in a high-pressure reactor, use water as a solvent, and stir to dissolve it for 4 to 20 hours under the protection of an inert gas at a reaction temperature of 180℃~240℃ and a pressure of 1~10 MPa to obtain a perfluorosulfonic acid resin aqueous dispersion. The aforementioned perfluorosulfonic acid resin solid has a polytetrafluoroethylene structure (-CF2-CF2-) as the main chain and -[OCF2C(CF3)F] as the main chain. m -O[CF2CF2]n-SO3H is composed of side chains, where m=0 or 1, n=1 or 2; The perfluorosulfonic acid resin solid content is 5% to 30% by weight; b. Place the perfluorosulfonic acid resin aqueous dispersion obtained in step a in a glass reactor, mix it with an organic solvent, and react it at a reaction temperature of 40℃~70℃ for 2~8 h to obtain the perfluorosulfonic acid resin alcohol aqueous dispersion. The organic solvent is any one or a mixture of two or more of ethanol, n-propanol, isopropanol, propylene glycol, glycerol, and n-butanol, and the weight percentage of the organic solvent is 20% to 60%.

2. The method for preparing the perfluorosulfonic acid resin alcohol-aqueous dispersion according to claim 1, characterized in that: The perfluorosulfonic acid resin solid mentioned in step a is from DuPont's Nafion. ® NR50, Solvay (Chemicals) Shanghai Co., Ltd.'s Aquivion ® PW-79S, Flemion from Asahi Glass, Japan ® Any one or more mixtures of F-9010.

3. The method for preparing the perfluorosulfonic acid resin alcohol aqueous dispersion according to claim 1 or 2, characterized in that: The inert gas mentioned in step a is any one or a mixture of two or more of nitrogen, helium, and argon.

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