Dispersion method of perfluorinated sulfonic acid resin

Abstract

The invention belongs to the field of proton exchange membrane fuel cells, and particularly relates to a dispersion method of perfluorinated sulfonic acid resin, which comprises the following steps: S1, adding the perfluorinated sulfonic acid resin into a blending solvent, and carrying out first dispersion treatment to obtain a first resin dispersion liquid; and S2, carrying out second dispersion treatment on the first resin dispersion liquid obtained in the step S1 to obtain the perfluorinated sulfonic acid resin dispersion liquid. Compared with the prior art, the problems that in the prior art, the technology is complex, the process is tedious, and the requirement for equipment is high are solved; the preparation of the perfluorinated sulfonic acid resin dispersion liquid with a simple process is realized, and the prepared perfluorinated sulfonic acid resin dispersion liquid has the characteristics of small particle size and narrow distribution.

Description

Technical Field

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

[0002] Perfluorosulfonic acid resin is a key material for proton exchange membranes and fuel cell catalyst layers. Its aggregate size and dispersion properties in solvents directly affect the key performance of proton exchange membranes and fuel cell catalyst layers. Therefore, it is of great significance to study the dispersion process of perfluorosulfonic acid resin.

[0003] In the prior art, the preparation of perfluorosulfonic acid resin dispersion mostly uses high-temperature and high-pressure conditions to directly dissolve perfluorosulfonic acid resin in a water / alcohol mixed solvent or an organic solvent (such as the preparation method of a perfluorosulfonic acid resin dispersion with uniformly dispersed molecular chains disclosed in Patent CN103146001A, the preparation method of a perfluorosulfonic acid resin dispersion disclosed in CN104140542A, the preparation method of perfluorosulfonic acid resin dispersion disclosed in CN112608494A, the preparation method of a perfluorosulfonic acid resin dispersion disclosed in CN114276561A, etc.). However, the high-temperature and high-pressure conditions not only make the dispersion process complex and the operation dangerous, but also introduce additional side reactions and generate impurities (such as the dehydroxylation of organic solvents to form ethers, etc.). An additional post-separation process is required to obtain a high-purity and usable perfluorosulfonic acid resin dispersion.

[0004] It can be seen that due to the complex process and cumbersome flow, it is difficult to guarantee the quality of perfluorosulfonic acid resin obtained by the previous technology, and the batch reproducibility is poor. Therefore, it is necessary to develop a perfluorosulfonic acid resin dispersion technology with a simple process. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for dispersing perfluorosulfonic acid resin to solve at least one of the above problems, so as to solve the problems of complex process, cumbersome flow and high equipment requirements in the prior art; realize the preparation of a perfluorosulfonic acid resin dispersion with a simple process, and the prepared perfluorosulfonic acid resin dispersion has the characteristics of small particle size and narrow distribution.

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

[0007] A method for dispersing perfluorosulfonic acid resin, comprising the following steps:

[0008] S1: Add perfluorosulfonic acid resin to a blend solvent, and obtain a first resin dispersion after the first dispersion treatment;

[0009] S2: Perform a second dispersion treatment on the first resin dispersion obtained in step S1 to obtain a perfluorosulfonic acid resin dispersion.

[0010] Preferably, in the perfluorosulfonic acid resin dispersion liquid, the mass ratio of the perfluorosulfonic acid resin is 0.01-60 wt%, and the balance is a blend solvent.

[0011] More preferably, in the perfluorosulfonic acid resin dispersion liquid, the mass ratio of the perfluorosulfonic acid resin is 0.1-40 wt%, and the balance is a blend solvent.

[0012] Preferably, the blend solvent includes an aprotic polar solvent.

[0013] Preferably, the blend solvent further includes a second solvent. The mass ratio of the aprotic polar solvent in the blend solvent is 1-100 wt%, and the balance is the second solvent.

[0014] Preferably, the second solvent includes one or both of water and alcohol. The mass ratio of water in the blend solvent is 0-95 wt%, and the mass ratio of alcohol in the blend solvent is 0-95 wt%.

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

[0016] More preferably, the alcohol includes one or more of ethanol, isopropanol, and n-propanol.

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

[0018] More preferably, the aprotic polar solvent includes one or both of N,N-dimethylformamide and dimethylacetamide.

[0019] Preferably, in step S1, the treatment temperature of the first dispersion treatment is 20-150 °C, and the treatment time is 1 min-128 h.

[0020] More preferably, in step S1, the treatment temperature of the first dispersion treatment is 20-90 °C, and the treatment time is 5-100 min.

[0021] Preferably, in step S2, the treatment temperature of the second dispersion treatment is 20-150 °C, and the treatment time is 1 min-128 h.

[0022] More preferably, in step S2, the treatment temperature of the second dispersion treatment is 20-90 °C, and the treatment time is 5-100 min.

[0023] Preferably, the first dispersion treatment and the second dispersion treatment include one or more of magnetic stirring, water bath ultrasonic treatment, high-speed shearing, cell disruption, homogenization, emulsification, and ball milling.

[0024] The working principle of the present invention is as follows:

[0025] Perfluorosulfonic acid resin is composed of a hydrophobic perfluorocarbon backbone and a hydrophilic sulfonated vinyl ether side chain. Its dissolution and dispersion properties in solvents depend on the solvent system, dispersion process, etc. Under a certain solvent system, the solubility of the main and side chains and the dielectric constant of the solvent determine the configuration, size of the perfluorosulfonic acid resin primary aggregates, and the interaction between the primary aggregates. By applying a dispersion process, the force between the primary aggregates can be broken, effectively dispersing the perfluorosulfonic acid resin aggregates to obtain a dispersion liquid with small particle size. Conventional dispersion methods, such as magnetic stirring, water bath ultrasonic treatment, high-speed shearing, cell disruption, homogenization, emulsification, ball milling, etc., can all break the force between the primary aggregates and achieve the preliminary effective dispersion of the perfluorosulfonic acid resin dispersion liquid. However, after one dispersion, the perfluorosulfonic acid resin will still undergo secondary aggregation behavior to form secondary aggregates. For example, the shearing force of magnetic stirring is relatively low, and it can only break the secondary aggregates with weak interactions to achieve partial dispersion; the intensity of water bath ultrasonic treatment or cell disruption is relatively large, which can further break the secondary aggregates with strong interactions to obtain a better dispersion effect. However, compared with magnetic stirring, the cost of water bath ultrasonic treatment or cell disruption is higher, and the thermal effect brought by long-term use will instead reduce the dispersion effect. Therefore, considering the cost and dispersion effect, this solution selects a two-step dispersion combination method of "magnetic stirring + water bath ultrasonic treatment or cell disruption", enabling the perfluorosulfonic acid resin to be fully dispersed in the dispersion liquid, and the overall combined process has low cost and high efficiency.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The preparation of the perfluorosulfonic acid resin dispersion liquid of the present invention is carried out under normal temperature and pressure. The preparation process is simple, safe and reliable, and is suitable for industrial use.

[0028] 2. The perfluorosulfonic acid resin dispersion liquid prepared by the present invention has a smaller particle size and a narrower distribution. Description of the Drawings

[0029] Figure 1 For the resin in the perfluorosulfonic acid resin dispersion liquids prepared in Comparative Example 1 and Test Examples 1-4: (a) weight-average molecular weight M w and number-average molecular weight M n , (b) molecular weight distribution PDI;

[0030] Figure 2 For the resin in the perfluorosulfonic acid resin dispersion liquids prepared in Comparative Example 1, Test Example 1 and Examples 1-2: (a) weight-average molecular weight M wThe number-average molecular weight M n , (b) the molecular weight distribution PDI. Specific implementation mode

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] In the following examples, if not otherwise specified, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0033] Test Example 1

[0034] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps: adding 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stirring at 400 rpm for 90 min at 25 °C using a magnetic stirrer to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0035] Test Example 2

[0036] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps: adding 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stirring at 400 rpm for 90 min at 40 °C using a magnetic stirrer to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0037] Test Example 3

[0038] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps: adding 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stirring at 400 rpm for 90 min at 60 °C using a magnetic stirrer to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0039] Test Example 4

[0040] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps: adding 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stirring at 400 rpm for 90 min at 80 °C using a magnetic stirrer to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0041] Example 1

[0042] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0043] (1) Adding 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stirring at 400 rpm for 90 min at 25 °C using a magnetic stirrer to obtain a first perfluorosulfonic acid resin dispersion;

[0044] (2) Transfer the first perfluorosulfonic acid resin dispersion to a water bath and ultrasonicate for 10 min to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0045] Example 2

[0046] A method for preparing a perfluorosulfonic acid resin dispersion, comprising the following steps:

[0047] (1) Add 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and stir with a magnetic stirrer at 400 rpm at 25 °C for 90 min to obtain the first perfluorosulfonic acid resin dispersion;

[0048] (2) Ultrasonicate the first perfluorosulfonic acid resin dispersion with a cell disruptor for 10 min to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0049] Comparative Example 1

[0050] A method for preparing a perfluorosulfonic acid resin dispersion, the specific steps are: add 0.5 g of perfluorosulfonic acid resin to 99.5 g of N,N-dimethylformamide, and then place it in a 25 °C environment and let it stand for 24 h to obtain a 0.5 wt% perfluorosulfonic acid resin dispersion.

[0051] Molecular weight test experiment:

[0052] For the perfluorosulfonic acid resin dispersions prepared in Examples 1-2, Test Examples 1-4 and Comparative Example 1, the molecular weight and molecular weight distribution were respectively detected by using the "GB / T 21864-2008 Standard Test Method for the Average Molecular Weight and Molecular Weight Distribution of Polystyrene High Performance Size Exclusion Chromatography". Here, the molecular weight and the molecular weight distribution PDI can indirectly reflect the hydrodynamic radius and its distribution information of the aggregates in the dispersion, that is, the larger the molecular weight, the larger the hydrodynamic radius, and the smaller the molecular weight distribution PDI, the narrower the aggregate particle size distribution.

[0053] As Figure 1 shown, the weight-average molecular weight M w 、number-average molecular weight M n and the molecular weight distribution PDI of the perfluorosulfonic acid resin dispersions prepared in Test Examples 1-4 all increase with the increase of the dispersion temperature, indicating that under high temperature conditions, the solvation effect of the molecular chain increases and becomes more extended, resulting in an increase in the hydrodynamic volume. In addition, at high temperature, the thermal motion of the molecular chain is enhanced, resulting in the entanglement of the molecular chains and the formation of aggregates with a larger hydrodynamic volume. Compared with Comparative Example 1, the M w 、M n and PDI of Test Example 1 are all lower, indicating that stirring at 25 °C for 90 min can effectively disperse large-size aggregates to obtain a perfluorosulfonic acid resin dispersion with small particle size and narrow distribution.

[0054] As Figure 2 shown, among the perfluorosulfonic acid resin dispersions prepared in Test Example 1 and Examples 1-2, the M w , M n and PDI of Example 1 are the lowest, indicating that stirring at room temperature for 90 min and then subjecting to water bath ultrasonic treatment for 10 min is the optimal process for preparing the dispersion. After stirring at room temperature for 90 min, the water bath ultrasonic treatment can further break the dynamically adhered aggregates and further reduce the aggregate particle size. The molecular weight obtained by high-power ultrasonic treatment using a cell disruptor is greater than that of ordinary ultrasonic treatment, which may be due to the entanglement between molecular chains caused by the thermal effect of high-power ultrasonic treatment and the yellowing and deterioration of the dispersion.

[0055] 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 effort. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for dispersing perfluorosulfonic acid resin, characterized in that, it comprises the following steps: S1: Add perfluorosulfonic acid resin into a blend solvent, and obtain a first resin dispersion after the first dispersion treatment; S2: Perform a second dispersion treatment on the first resin dispersion obtained in step S1 to obtain a perfluorosulfonic acid resin dispersion.

2. The method for dispersing perfluorosulfonic acid resin according to claim 1, characterized in that, in the perfluorosulfonic acid resin dispersion, the mass ratio of perfluorosulfonic acid resin is 0.01 - 60 wt%, and the rest is the blend solvent.

3. The method for dispersing perfluorosulfonic acid resin according to claim 1, characterized in that, the blend solvent includes an aprotic polar solvent.

4. The method for dispersing perfluorosulfonic acid resin according to claim 3, characterized in that, the blend solvent further includes a second solvent, and the mass ratio of the aprotic polar solvent in the blend solvent is 1 - 100 wt%, and the rest is the second solvent.

5. The method for dispersing perfluorosulfonic acid resin according to claim 4, characterized in that, the second solvent includes one or both of water and alcohol, the mass ratio of water in the blend solvent is 0 - 95 wt%, and the mass ratio of alcohol in the blend solvent is 0 - 95 wt%.

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

7. The method for dispersing perfluorosulfonic acid resin according to claim 3, characterized in that, the aprotic polar solvent includes one or more of N,N - dimethylformamide, dimethyl sulfoxide, N - methylpyrrolidone and dimethylacetamide.

8. The method for dispersing perfluorosulfonic acid resin according to claim 1, characterized in that, in step S1, the treatment temperature of the first dispersion treatment is 20 - 150 °C, and the treatment time is 1 min - 128 h.

9. The method for dispersing perfluorosulfonic acid resin according to claim 1, characterized in that, in step S2, the treatment temperature of the second dispersion treatment is 20 - 150 °C, and the treatment time is 1 min - 128 h.

10. The method for dispersing perfluorosulfonic acid resin according to claim 1, characterized in that, the first dispersion treatment and the second dispersion treatment include one or more of magnetic stirring, water bath ultrasonic, high - speed shearing, cell disruption, homogenization, emulsification and ball milling.

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