Formula and preparation method of high-viscosity volatile membrane casting solution

Abstract

The invention relates to the technical field of chemical engineering, and provides a formula and a preparation method of a high-viscosity volatile membrane casting solution, and the formula of the membrane casting solution comprises the following components in percentage by mass: 40%-80% of a basic solvent, 10%-40% of a polymer substance, 5%-15% of an organic additive, 5%-20% of an inorganic additive and 3%-10% of a cosolvent, the basic solvent comprises a high-boiling-point organic solution which is a combination of two or more of N, N-dimethylformamide, N-methyl-2-pyrrolidone, pyrrolidone and dimethyl sulfoxide, and the macromolecular substance comprises perfluorinated sulfonic acid resin and polyvinyl alcohol. According to the present invention, by introducing the polymer substance and the new solution polymerization process, the film casting liquid finished product can have the high viscosity so as to form the thick coating in the casting film preparation process, and due to the high volatility of the film casting liquid, the drying and curing time is significantly shortened, the film casting quality is improved, and the generation of the hole phenomenon is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a formula of a high-viscosity volatile film casting liquid and a preparation method thereof. Background Art

[0002] Against the backdrop of global energy shortages, new energy vehicles and energy storage technologies are gaining increasing attention. As ideal energy storage components, lithium batteries and vanadium batteries have gained wider attention. Among them, vanadium batteries have significant advantages in large-scale, high technology and industrialization, showing broad application prospects in various new energy fields such as wind energy and solar energy.

[0003] As the core material of lithium batteries and vanadium batteries, perfluorosulfonic acid ion membrane plays a decisive role in the performance and service life of batteries. However, due to its high cost, it has become the main bottleneck restricting the development and application of batteries. During the production process, solutions with different boiling points evaporate at high temperatures, which will lead to different surface phenomena and produce holes. Therefore, high-viscosity casting liquid is required. The viscosity can be adjusted according to the solid content and the temperature and rotation speed of the solution preparation. The quality of the solution will directly affect its operation in the machine, and then affect the performance of the ion membrane after processing.

[0004] At present, lithium batteries and vanadium batteries have been industrialized in many countries. In order to further promote the development and application of battery technology, the localization of perfluorosulfonic acid ion membrane diaphragms needs to be solved urgently. Only through independent research and development and production, and reducing the production cost of perfluorosulfonic acid ion membranes, can we better meet market demand and promote the further development of new energy vehicles and energy storage technologies.

[0005] Therefore, a new high-viscosity and volatile casting liquid formula is needed to overcome the problems existing in the prior art and provide a better casting effect. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a formula and preparation method for a high-viscosity and volatile casting liquid, which solves the problems of the existing casting liquid having high production cost, low viscosity and poor volatility, resulting in poor preparation effect of the finished film.

[0007] To achieve the above objectives, the present invention is implemented through the following technical scheme: a high-viscosity and volatile casting liquid formula, including the following formulas in mass percentage: basic solvent accounts for 40% to 80% of the total formula, high molecular weight substances account for 10% to 40% of the total formula, organic additives account for 5% to 15% of the total formula, inorganic additives account for 5% to 20% of the total formula, and co-solvents account for 3% to 10%.

[0008] Preferably, the base solvent includes a high boiling point organic solution: N, N-dimethylformamide, N-methyl-2-pyrrolidone, a combination of two or more of pyrrolidone and dimethyl sulfoxide.

[0009] Preferably, the polymer substance includes perfluorosulfonic acid resin and polyvinyl alcohol.

[0010] Preferably, the organic additives include non-fluorine-based resins, sulfonated polyetheretherketone and polybenzimidazole.

[0011] Preferably, the inorganic additives include carbon nanotubes, nano titanium dioxide and zinc oxide.

[0012] Preferably, the co-solvent is a combination of two or more of ethanol, ethylene glycol and isopropanol.

[0013] A method for preparing a high-viscosity volatile casting solution of the present invention is used to prepare the above-mentioned high-viscosity volatile casting solution, comprising the following steps: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: Add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Filter and degas the obtained casting solution to remove impurities and bubbles to obtain a high-viscosity and volatile casting solution.

[0014] Preferably, in step four, the casting liquid is filtered using a filter screen or filter paper to remove larger particles or solid impurities, and the degassing is to place the casting liquid in a vacuum chamber to reduce the pressure and discharge bubbles from the liquid to obtain a more uniform, bubble-free casting liquid.

[0015] Preferably, in step one, step two and step three, the stirring time of the materials is 6 hours to 24 hours, and the stirring temperature is 240° C. to 260° C.

[0016] The present invention provides a high-viscosity and volatile casting liquid formula and preparation method. It has the following beneficial effects: 1. The present invention introduces polymer substances and organic and inorganic additives to make them have higher viscosity, thereby forming a thicker coating during the film-casting process. Due to their high volatility, the drying and curing time are significantly shortened, which not only improves the quality of the cast film, but also allows the solvent to evaporate quickly after casting, achieving faster drying and curing speeds and reducing the generation of voids.

[0017] 2. The present invention can flexibly adjust the proportion of each component according to specific application requirements to adapt to different usage requirements. The casting liquid formula has the characteristics of high viscosity and high volatility, and has good adjustability and film performance, and is suitable for a variety of application fields. Through the formula of the present invention, a casting liquid with excellent performance can be obtained, and it is suitable for a variety of different application scenarios. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention provides a high-viscosity volatile casting solution formula, including the following formulas in mass percentage: The basic solvent accounts for 40% to 60% of the total formula, the polymer substance accounts for 20% to 40% of the total formula, the organic additive accounts for 5% to 15% of the total formula, and the inorganic additive accounts for 5% to 20% of the total formula.

[0020] Through the combination of the above ingredients, the basic solvent, polymer substance, co-solvent, organic additive and inorganic additive in the formula interact with each other to achieve the preparation of high-viscosity and volatile casting liquid. After the steel strip casting film method, this casting liquid forms a uniform and continuous film layer. The film layer has a high viscosity and is not easy to flow or drip. At the same time, the film layer has good volatility. The solvent in the film liquid can evaporate quickly, so that the film layer dries quickly and forms a dense structure.

[0021] The basic solvent includes a high boiling point organic solution: N, N-dimethylformamide is 19% to 23%, N-methyl-2-pyrrolidone is 21% to 25%, pyrrolidone is 16% to 38%, and dimethyl sulfoxide is 11% to 24%.

[0022] By controlling the ratio of different solvents, the viscosity of the casting liquid can be adjusted. The use of high-boiling point organic solvents can increase the viscosity of the membrane liquid, thereby improving its lubricity and fluidity, which helps to achieve uniform and easy-to-operate membrane formation during coating or casting. Basic solvents have good solubility for many polymer materials. They can effectively dissolve polymer substances in solutions to form a uniform membrane liquid system, which helps to prepare non-porous and evenly distributed membrane materials. Basic solvents are usually used as reaction media to provide a suitable reaction environment.

[0023] The polymer substance includes perfluorosulfonic acid resin and polyvinyl alcohol.

[0024] Perfluorosulfonic acid resin has excellent chemical resistance and can resist corrosion from many strong acids, strong bases and solvents. Therefore, adding perfluorosulfonic acid resin to the casting solution can improve the chemical resistance of the membrane material. Perfluorosulfonic acid resin is an ion exchange resin that can react with ions in the solution by exchanging ions. It can be used to prepare ion exchange membranes with good ion selectivity and ion transfer properties.

[0025] Among the organic additives, non-fluorine-based resin accounts for 10% to 33%, sulfonated polyetheretherketone accounts for 2% to 24%, polytetrafluoroethylene accounts for 10% to 46%, and polybenzimidazole accounts for 0.1% to 5%.

[0026] Non-fluorine-based resin organic additives can make the membrane material have good flexibility and ductility, improve its mechanical strength, including anti-bending and tensile properties. Non-fluorine-based resin organic additives have low cost and can introduce a variety of ion exchange groups to be made into anion exchange membranes, amphoteric ion exchange membranes, etc. They have high ion selectivity and can improve the coulombic efficiency in the battery, reduce capacity attenuation, and the membrane density will be better and the ion selectivity will be higher.

[0027] Among the inorganic additives, carbon nanotubes account for 20% to 46%, nano titanium dioxide accounts for 20% to 55%, and zinc oxide accounts for 0% to 7%.

[0028] The purpose of modification by adding inorganic substances is to introduce some two-dimensional and three-dimensional structural materials. By increasing the conductivity and changing the channel pore size to improve the ion selectivity, the prepared finished membrane can have better performance.

[0029] The co-solvent contains 10% to 53% ethanol, 5% to 31% ethylene glycol, and 10% to 25% isopropanol.

[0030] In the present invention, the co-solvent mainly affects the boiling point of the solution, so that the low boiling point solvent replaces the high boiling point solvent during the solution preparation process.

[0031] Furthermore, the present invention also provides a method for preparing a high-viscosity volatile casting solution, comprising the following steps: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: Add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Filter and degas the obtained casting solution to remove impurities and bubbles to obtain a high-viscosity and volatile casting solution.

[0032] In step 1 to step 3, components such as basic solvent, polymer, organic additive, inorganic additive and co-solvent are added to the container, and after sufficient stirring and mixing, each component can be evenly dispersed in the solvent to form a uniform casting liquid, which helps to obtain uniform film thickness and chemical composition distribution, improve the quality and performance stability of the film, and by adding components such as polymer, organic additive and inorganic additive in step 2 and step 3, the viscosity and performance of the casting liquid can be adjusted. The high-viscosity casting liquid has good fluidity and lubricity, which is conducive to the operability and film formation in the casting process. In the above steps, the proportion of each component in the formula can be adjusted according to the specific application requirements, so that the characteristics of the film, such as hardness, flexibility, and chemical resistance, can be flexibly adjusted to meet the needs of different application fields. In step 4, impurities and bubbles in the casting liquid can be removed by filtering and degassing treatment to improve the purity and quality of the liquid.

[0033] In step 4, filtering is performed by filtering the casting solution using a filter screen or filter paper filter to remove larger particles or solid impurities; Degassing, placing the casting liquid in a vacuum chamber, reducing the pressure, allowing bubbles to be discharged from the liquid, and obtaining a more uniform, bubble-free casting liquid. Through filtration and degassing treatment, the quality of the coating can be improved, ensuring the flatness and smoothness of the coating. At the same time, removing particles or solid impurities and bubbles can reduce coating defects and improve the appearance and performance of the coating.

[0034] The material stirring time in step 1, step 2 and step 3 is 6h to 24h, and the stirring temperature is 240°C to 260°C.

[0035] By carrying out the stirring and drying treatment within an appropriate time and temperature range, the casting solution can be fully mixed, the reaction can be promoted, and a good quality film can be obtained by the steel belt casting film forming method.

[0036] The present invention will be further described below in conjunction with specific embodiments: Embodiment 1: The embodiment of the present invention provides a high-viscosity volatile casting liquid formula, including the following proportions: The basic solvent accounts for 50% of the total formula, the polymer substance accounts for 22% of the total formula, the organic additive accounts for 10% of the total formula, the inorganic additive accounts for 15% of the total formula, and the co-solvent accounts for 3% of the total formula.

[0037] The basic solvent includes high boiling point organic solution: N, N-dimethylformamide is 20%, N-methyl-2-pyrrolidone is 21%, pyrrolidone is 35%, and dimethyl sulfoxide is 24%; The polymer material contains 50% perfluorosulfonic acid resin and 50% sulfonated polyetheretherketone; The organic additives include 30% non-fluorine resin, 20% sulfonated polyetheretherketone, 7% polytetrafluoroethylene, and 43% polybenzimidazole; Among the inorganic additives, carbon nanotubes account for 40%, nano-titanium dioxide accounts for 55%, and zinc oxide accounts for 5%; The co-solvent contains 50% ethanol, 30% ethylene glycol and 20% isopropanol.

[0038] The embodiment of the present invention provides a method for preparing a high-viscosity volatile casting solution, comprising the following steps: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: Add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Filter and degas the obtained casting liquid to remove impurities and bubbles to obtain a high-viscosity, non-volatile casting liquid.

[0039] The material stirring time in step 1, step 2 and step 3 is 15 hours, and the stirring temperature is 240°C.

[0040] Embodiment 2: The embodiment of the present invention provides a high-viscosity volatile casting liquid formula, including the following proportions: The basic solvent accounts for 45% of the total formula, the polymer substance accounts for 20% of the total formula, the organic additive accounts for 15% of the total formula, the inorganic additive accounts for 18% of the total formula, and the co-solvent accounts for 2% of the total formula.

[0041] The base solvent includes high boiling point organic solution: N, N-dimethylformamide is 21%, N-methyl-2-pyrrolidone, pyrrolidone is 34%, and dimethyl sulfoxide is 23%; Among the polymer substances, perfluorosulfonic acid resin accounts for 46% and sulfonated polyetheretherketone accounts for 54%; The organic additives include 30% non-fluorinated resin, 25% sulfonated polyetheretherketone, and 45% polybenzimidazole; Among the inorganic additives, carbon nanotubes account for 40%, nano-titanium dioxide accounts for 55%, and zinc oxide accounts for 5%; The co-solvent contains 50% ethanol, 30% ethylene glycol and 20% isopropanol.

[0042] The embodiment of the present invention provides a method for preparing a high-viscosity volatile casting solution, comprising the following steps: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: gradually add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Filter and degas the obtained casting solution to remove impurities and bubbles to obtain a high-viscosity and volatile casting solution.

[0043] The stirring time in step 1, step 2 and step 3 is 15 hours, and the stirring temperature is 250°C.

[0044] Embodiment three: The embodiment of the present invention provides a high-viscosity volatile casting liquid formula, including the following proportions: The basic solvent accounts for 40% of the total formula, the polymer substance accounts for 25% of the total formula, the organic additive accounts for 15% of the total formula, the inorganic additive accounts for 19% of the total formula, and the co-solvent accounts for 1% of the total formula.

[0045] The basic solvent includes high boiling point organic solvents: 22% N, N-dimethylformamide, 24% dimethylacetamide, 32% pyrrolidone, and 22% dimethyl sulfoxide; Among the polymer substances, perfluorosulfonic acid resin accounts for 49% and sulfonated polyetheretherketone accounts for 51%; The organic additives include 55% non-fluorinated resin, 25% sulfonated polyetheretherketone, 10% sulfonated polyetheretherketone, and 10% polybenzimidazole; Among the inorganic additives, carbon nanotubes account for 40%, nano-titanium dioxide accounts for 55%, and zinc oxide accounts for 5%; The co-solvent contains 60% ethanol, 30% ethylene glycol and 10% isopropanol.

[0046] The embodiment of the present invention provides a method for preparing a high-viscosity volatile casting solution, comprising the following steps: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: Add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Adjust the proportions of the components in the formula to meet specific application requirements; Step 5: Filter and degas the obtained casting solution to remove impurities and bubbles to obtain a low-viscosity and volatile casting solution.

[0047] The stirring time in step 1, step 2 and step 3 is 6 hours, and the stirring temperature is 260°C.

[0048] Comparative Example 1: The comparative example of the present invention provides a casting solution formula, comprising the following components in parts by weight: 10 parts of Nafion powder, 2 parts of acetone, 14 parts of ethanol, and 5 parts of N-methyl-2-pyrrolidone. Specifically, the preparation method of the casting solution formula comprises the following steps: Step 1, adding Nafion powder to the above organic solvent, stirring the solution at room temperature until the Nafion powder is completely dissolved; Step 2: Filter the solution to remove undissolved impurities; Step 3: pour the filtered solution into a film casting plate or mold, and then dry it in a constant temperature oven or vacuum dryer to evaporate the solvent and form a film; Step 4: After drying, the film is peeled off from the film casting plate or mold to obtain a perfluorosulfonic acid ion membrane.

[0049] Table 1. Viscosity, volatility and comprehensive parameters of film performance of the casting solutions prepared in Comparative Example 1, Example 2, Example 3 and Comparative Example 1: Viscosity (cps) volatility(%) Membrane performance Embodiment 1 4760 60 Excellent Embodiment 2 4250 80 Excellent Embodiment 3 3940 81 good Comparative Example 1 1500 85 medium Comparing the casting solutions prepared in Example 1, Example 2, Example 3 and Comparative Example 1, the viscosity, volatility and membrane performance of the perfluorosulfonic acid ion membrane finally obtained by the steel strip casting membrane method are shown in the following table: Table 2, performance test parameters of perfluorosulfonic acid ion membrane prepared in Example 1, Example 2, Example 3 and Comparative Example 1: Tensile strength (MPa) Tensile elastic modulus (MPa) Puncture strength (Mpa) Embodiment 1 30 32 585 Embodiment 2 31 28 559 Embodiment 3 28 29 546 Comparative Example 1 18 20 415 According to the above data, it can be seen that there are differences in viscosity and volatility among Example 1, Example 2 and Example 3. Example 1 has higher viscosity and lower volatility, and is suitable for application scenarios requiring thicker coatings and longer curing times. Example 2 has higher viscosity and higher volatility, and is suitable for certain application scenarios requiring thicker and faster drying. Example 3 has lower viscosity and higher volatility, and is suitable for application scenarios requiring thinner coatings and faster drying.

[0050] Based on the formula characteristics and comparative experimental results of the above three embodiments, the high-viscosity and volatile casting liquid formula has flexible formula, viscosity control, volatility adjustment, and excellent membrane performance. In general, the high-viscosity and volatile casting liquid formula has flexibility, adjustability and good membrane performance, and is suitable for a variety of application fields.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high viscosity volatile casting solution formula, characterized in that: The formulation includes the following mass percentages: The basic solvent accounts for 40% to 80% of the total formula, the polymer substance accounts for 10% to 40% of the total formula, the organic additive accounts for 5% to 15% of the total formula, the inorganic additive accounts for 5% to 20% of the total formula, and the co-solvent accounts for 3% to 10%.

2. A high viscosity volatile casting solution formulation according to claim 1, characterized in that: The basic solvent includes a high boiling point organic solution: N, N-dimethylformamide, N-methyl-2-pyrrolidone, and a combination of two or more of pyrrolidone and dimethyl sulfoxide.

3. A high viscosity volatile casting solution formulation according to claim 1, characterized in that: The polymer substance includes perfluorosulfonic acid resin and polyvinyl alcohol.

4. A high viscosity volatile casting solution formulation according to claim 1, characterized in that: The organic additives include non-fluorine resin, sulfonated polyetheretherketone and polybenzimidazole.

5. A high viscosity volatile casting solution formulation according to claim 1, characterized in that: The inorganic additives include carbon nanotubes, nano titanium dioxide and zinc oxide.

6. A high viscosity volatile casting solution formulation according to claim 1, characterized in that: The co-solvent is a combination of two or more of ethanol, ethylene glycol and isopropanol.

7. A method for preparing a high-viscosity volatile casting solution, according to a high-viscosity volatile casting solution formula according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Add the base solvent into a container and mix it thoroughly under stirring; Step 2: Add the polymer substance and keep stirring until a uniform mixture is formed; Step 3, adding organic additives, inorganic additives and co-solvents, and continuing to stir to obtain a uniform casting solution; Step 4: Filter and degas the obtained casting solution to remove impurities and bubbles to obtain a high-viscosity and volatile casting solution.

8. The method for preparing a high-viscosity volatile casting solution according to claim 7, characterized in that: In step 4, the casting liquid is filtered using a filter screen or filter paper to remove larger particles or solid impurities. The degassing is to place the casting liquid in a vacuum chamber to reduce the pressure and discharge bubbles from the liquid to obtain a more uniform, bubble-free casting liquid.

9. The method for preparing a high-viscosity volatile casting solution according to claim 7, characterized in that: In the step 1, step 2 and step 3, the stirring time of the materials is 6 hours to 24 hours, and the stirring temperature is 240° C. to 260° C.