Preparation method of perfluorinated sulfonic acid resin dispersion liquid

Abstract

The invention belongs to the field of proton exchange membrane fuel cells, and particularly relates to a preparation method of a perfluorinated sulfonic acid resin dispersion liquid, which comprises the following steps: S1, blending water, alcohol and a third solvent according to a ratio, and uniformly stirring at room temperature to obtain a blended solvent; s2, adding the perfluorinated sulfonic acid resin into the blending solvent, and stirring to obtain the perfluorinated sulfonic acid resin dispersion liquid. Compared with the prior art, the problems that in the prior art, the preparation process is complex, and the prepared dispersion liquid is high in viscosity are solved; the preparation can be completed at normal temperature and normal pressure, and the prepared perfluorinated sulfonic acid resin dispersion liquid is relatively low in viscosity and convenient to further process and form a film.

Description

Technical Field

[0001] The present invention belongs to the field of proton exchange membrane fuel cells, and particularly relates to a preparation method of a perfluorosulfonic acid resin dispersion liquid. Background Art

[0002] Hydrogen fuel cells are widely used in new energy vehicles, stationary power stations and other fields due to their advantages such as high power density and low carbon emissions. As the "heart" of hydrogen fuel cells, the proton exchange membrane plays a role in conducting protons and isolating the anode and cathode reaction gases in the battery components, and is a key component that determines the performance, life and cost of fuel cells. The perfluorosulfonic acid resin dispersion liquid is one of the core technologies for preparing high-quality perfluorinated proton membranes, and thus has attracted much attention.

[0003] In this field, various preparation methods of perfluorosulfonic acid resin dispersion liquids have been proposed in the prior art. For example, US Patent No. US4433082A discloses a preparation method of a perfluorosulfonic acid resin dispersion liquid, which uses water and lower alcohols as solvents and stirs for 3 - 18 hours under high temperature and high pressure (≥220°C, ≥3MPa) conditions to obtain the perfluorosulfonic acid resin dispersion liquid. Chinese Patent No. CN101273487B and US Patent No. US20130210943A1 provide a relatively simple preparation process for perfluorosulfonic acid resin dispersion liquids, and their preparation temperature and pressure are reduced to 140 - 160°C and 0.88 - 1.88MPa. The dispersion liquid preparation technologies mentioned in previous publicly disclosed patents all involve high temperature and high pressure conditions, and the process is relatively complex. In addition, the existing preparation of perfluorosulfonic acid resin dispersion liquids usually selects a water / alcohol blend system as the dispersion solvent, and the viscosity of the dispersion liquid is relatively high, which is not conducive to film-forming processing.

[0004] Therefore, it is necessary to develop a simple preparation method of the dispersion liquid, and a dispersion liquid with high solid content and low viscosity can be obtained, which provides necessary conditions for the preparation of high conductivity composite reinforced proton membranes. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a perfluorosulfonic acid resin dispersion liquid to solve at least one of the above problems, so as to solve the problems of complex preparation process and high viscosity of the obtained dispersion liquid in the prior art; it realizes the preparation can be completed at normal temperature and pressure, and the viscosity of the obtained perfluorosulfonic acid resin dispersion liquid is relatively low, which is convenient for further film-forming processing.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A preparation method of a perfluorosulfonic acid resin dispersion liquid includes the following steps:

[0008] S1: Blend water, alcohol and a third solvent in proportion, and stir evenly at room temperature to obtain a blended solvent;

[0009] S2: Add perfluorosulfonic acid resin into a blend solvent and stir to obtain a perfluorosulfonic acid resin dispersion.

[0010] Preferably, in the perfluorosulfonic acid resin dispersion, the mass ratio of perfluorosulfonic acid resin is 0.1 - 60 wt%, and the rest is the blend solvent.

[0011] More preferably, in the perfluorosulfonic acid resin dispersion, the mass ratio of perfluorosulfonic acid resin is 10 - 35 wt%, and the rest is the blend solvent.

[0012] Preferably, in the blend solvent, the mass ratio of alcohol is 1 - 90 wt%; the mass ratio of the third solvent is 0 - 50 wt% and not 0 wt%; the rest is water.

[0013] Preferably, in the blend solvent, the mass ratio of alcohol is 10 - 80 wt%; the mass ratio of the third solvent is 2 - 20 wt%; the rest is water.

[0014] More preferably, in the blend solvent, the mass ratio of alcohol is 25 - 80 wt%; the mass ratio of the third solvent is 2 - 15 wt%; the rest is water.

[0015] Preferably, the alcohol includes one or more of methanol, ethanol, isopropanol, n - propanol, ethylene glycol, propylene glycol, and glycerol.

[0016] Preferably, the third solvent is an aprotic polar solvent.

[0017] Preferably, the third solvent includes one or more of dimethylacetamide, N,N - dimethylformamide, dimethyl sulfoxide, and N - methylpyrrolidone.

[0018] Preferably, the third solvent includes one or more of dimethylacetamide, N,N - dimethylformamide, and N - methylpyrrolidone.

[0019] Preferably, the stirring is carried out at normal temperature and pressure.

[0020] Preferably, the treatment time of the stirring is 24 - 128 h.

[0021] More preferably, the treatment time of the stirring is 72 - 96 h.

[0022] The working principle of the present invention is:

[0023] The present invention aims to solve the problems of complex preparation process, high viscosity, and difficulty in film processing of perfluorosulfonic acid resin dispersion. For the preparation process, the present invention provides a simple stirring paddle dispersion process at normal temperature and pressure to prepare perfluorosulfonic acid resin dispersion, and the dispersion strength is sufficient to break the interaction between aggregates to achieve effective dispersion. The viscosity of the dispersion is derived from the conformation of primary aggregates and the formation of large-sized secondary aggregates due to the interaction between primary aggregates. By changing the conformation of primary aggregates and breaking the cross-linking between aggregates, the viscosity can be effectively reduced. Water / alcohol is a common solvent for perfluorosulfonic acid resin, and the difference in solubility parameters of its main and side chains determines the rod-like particle configuration of perfluorosulfonic acid resin with a hydrophobic carbon-fluorine main chain overlapping inside and a hydrophilic sulfonic acid side chain facing outside. The main reasons for the reduction of dispersion viscosity caused by the introduction of the third solvent include: (1) some rod-like particles are transformed into coil configurations, the hydrodynamic radius of aggregates becomes smaller, and the viscosity decreases; (2) the formation of coil conformations shields some charges, resulting in a reduction in the self-assembly behavior of primary aggregates induced by undissociated hydrogen, breaking the interaction between aggregates, and reducing the viscosity. Therefore, by introducing a suitable third solvent, the viscosity of the dispersion can be effectively reduced.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The preparation of perfluorosulfonic acid resin dispersion in the present invention is carried out at normal temperature and pressure, with a simple preparation process, safe and reliable, and suitable for industrial use.

[0026] 2. The dispersion solvent formula provided by the present invention can effectively reduce the viscosity of perfluorosulfonic acid resin dispersion, facilitating film processing.

[0027] 3. The present invention can prepare perfluorosulfonic acid resin dispersion with high solid content and low viscosity, laying a solid foundation for the preparation of high-conductivity composite reinforced proton membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is the viscosity test results of perfluorosulfonic acid resin dispersions prepared in the comparative example and Examples 1-4;

[0029] Figure 2 FIG. is the pH test results of perfluorosulfonic acid resin dispersions prepared in the comparative example and Examples 1-4. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will be described in detail below with reference to the drawings and specific examples.

[0031] In the following examples, if not otherwise specified, the reagents used are conventional commercially available products, and the methods adopted are well-known means in the art.

[0032] Example 1

[0033] A preparation method of a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0034] (1) Prepare 70 g of a mixed solvent by mixing water, ethanol, and dimethylacetamide in a mass ratio of 1:3:0.1;

[0035] (2) Add 30 g of perfluorosulfonic acid resin to 70 g of the mixed solvent, and stir with a stirrer at 400 rpm for 96 h under normal temperature and pressure to obtain a perfluorosulfonic acid resin dispersion with a solid content of 30 wt%.

[0036] Example 2

[0037] A preparation method of a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0038] (1) Prepare 70 g of a mixed solvent by mixing water, ethanol, and dimethylacetamide in a mass ratio of 1:3:0.3;

[0039] (2) Add 30 g of perfluorosulfonic acid resin to 70 g of the mixed solvent, and stir with a stirrer at 400 rpm for 96 h under normal temperature and pressure to obtain a perfluorosulfonic acid resin dispersion with a solid content of 30 wt%.

[0040] Example 3

[0041] A preparation method of a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0042] (1) Prepare 70 g of a mixed solvent by mixing water, ethanol, and dimethylacetamide in a mass ratio of 1:3:0.5;

[0043] (2) Add 30 g of perfluorosulfonic acid resin to 70 g of the mixed solvent, and stir with a stirrer at 400 rpm for 96 h under normal temperature and pressure to obtain a perfluorosulfonic acid resin dispersion with a solid content of 30 wt%.

[0044] Example 4

[0045] A preparation method of a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0046] (1) Prepare 70 g of a mixed solvent by mixing water, ethanol, and N,N-dimethylformamide in a mass ratio of 1:3:0.3;

[0047] (2) Add 30 g of perfluorosulfonic acid resin to 70 g of the mixed solvent, and stir with a stirrer at 400 rpm for 96 h under normal temperature and pressure to obtain a perfluorosulfonic acid resin dispersion with a solid content of 30 wt%.

[0048] Comparative Example

[0049] A preparation method of a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0050] (1) Prepare a 70 g mixed solvent by mixing water and ethanol at a mass ratio of 1:3.

[0051] (2) Add 30 g of perfluorosulfonic acid resin to 70 g of the mixed solvent, and stir with a paddle at 400 rpm for 96 h under normal temperature and pressure to obtain a perfluorosulfonic acid resin dispersion with a solid content of 30 wt%.

[0052] Test on the properties of the dispersion:

[0053] 1. Viscosity test of the dispersion

[0054] Use the perfluorosulfonic acid resin dispersions prepared in Examples 1-4 and the comparative example respectively, and use a digital viscometer (NDJ series) to test the viscosity of the dispersion. Test conditions: test environment at 25 °C, rotor speed 60 rpm, time 60 s.

[0055] 2. pH test of the dispersion

[0056] Use the perfluorosulfonic acid resin dispersions prepared in Examples 1-4 and the comparative example respectively, and use a pH meter (PHS-3C, Leici) to test the pH of the dispersion. Test conditions: test environment at 25 °C, after placing the pH meter in the dispersion and stabilizing for 15 minutes, read the data.

[0057] As Figure 1 shown, the viscosities of the perfluorosulfonic acid resin dispersions prepared in Examples 1-4 are all lower than those of the dispersion prepared in the comparative example, indicating that the introduction of the third solvent (dimethylacetamide or N,N-dimethylformamide) can effectively reduce the viscosity of the dispersion, and the higher the addition amount of the third solvent, the more obvious the viscosity decrease.

[0058] As Figure 2 shown, the pH values of the perfluorosulfonic acid resin dispersions prepared in Examples 1-4 are all higher than those of the dispersion prepared in the comparative example, indicating that the introduction of the third solvent (dimethylacetamide or N,N-dimethylformamide) can effectively shield the charges in the dispersion, and the higher the addition amount of the third solvent, the higher the pH value.

[0059] The main reason for the above is as follows: in the dispersion prepared in the comparative example, the perfluorosulfonic acid resin presents rod-like particles with the main chain overlapping inside and the sulfonic acid side chains facing outward, and the sulfonate groups are exposed outside. The pH of the dispersion is relatively low. The intrinsic conformation of the rod-like particles and the interaction between the rod-like particles through undissociated hydrogen result in a relatively high viscosity of the dispersion. However, in Examples 1-4, the introduction of dimethylacetamide or N,N-dimethylformamide makes part of the perfluorosulfonic acid resin present a coil configuration with the main chain outside and the sulfonate groups wrapped inside, resulting in partial charge shielding, an increase in the pH of the dispersion, and a decrease in viscosity. Generally speaking, the conformation of aggregates and the charge shielding effect in the dispersion are the key reasons for the decrease in the viscosity of the dispersion.

[0060] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention as disclosed should be within the protection scope of the present invention.

Claims

1. A method for preparing a perfluorosulfonic acid resin dispersion, characterized in that, it comprises the following steps: S1: Mix water, alcohol and a third solvent in proportion and stir evenly at room temperature to obtain a blended solvent; S2: Add the perfluorosulfonic acid resin to the blended solvent and stir to obtain a perfluorosulfonic acid resin dispersion.

2. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, in the perfluorosulfonic acid resin dispersion, the mass proportion of the perfluorosulfonic acid resin is 0.1 - 60 wt%, and the balance is the blended solvent.

3. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, in the blended solvent, the mass proportion of alcohol is 1 - 90 wt%; the mass proportion of the third solvent is 0 - 50 wt% and not 0 wt%; the balance is water.

4. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 3, characterized in that, in the blended solvent, the mass proportion of alcohol is 10 - 80 wt%; the mass proportion of the third solvent is 2 - 20 wt%; the balance is water.

5. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, the alcohol includes one or more of methanol, ethanol, isopropanol, n-propanol, ethylene glycol, propylene glycol and glycerol.

6. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, the third solvent is an aprotic polar solvent.

7. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 6, characterized in that, the third solvent includes one or more of dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

8. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 7, characterized in that, the third solvent includes one or more of dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.

9. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, the stirring is carried out at normal temperature and pressure.

10. The method for preparing a perfluorosulfonic acid resin dispersion according to claim 1, characterized in that, the treatment time of the stirring is 24 - 128 h.

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