Production method of high-temperature-resistant lithium battery base membrane

Abstract

The invention discloses a production method of a high-temperature-resistant lithium battery base membrane. The lithium battery base membrane is prepared from PA6, PA10T / 66, magnesium hydroxide, glass fibers, zinc borate, an antioxidant, silane coupling agent modified silicon dioxide and a DOPO-triglycidyl p-aminophenol reaction product. The high-temperature-resistant lithium battery base membrane designed by the invention not only has excellent high-temperature resistance, but also has good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of lithium battery base film technology, specifically a method for producing a high-temperature resistant lithium battery base film. Background Technology

[0002] Existing lithium battery packaging films generally consist of a nylon base film layer, an aluminum foil layer, and a heat-sealing layer. They can be manufactured using either dry or thermal processes. The performance of the lithium battery packaging film is closely related to the lifespan of the lithium battery. With the increasingly widespread application of lithium batteries in electric vehicles, energy storage systems, and other fields, higher requirements are being placed on the high-temperature resistance of lithium battery packaging films. Traditional lithium battery packaging films may experience thermal shrinkage and deformation under high-temperature environments, thus affecting the safety and lifespan of the lithium battery. Therefore, developing a high-temperature resistant lithium battery base film has become a research hotspot in the industry. This base film needs to possess good thermal stability, high-temperature shrinkage resistance, and mechanical strength to ensure the safe and stable operation of lithium batteries under high-temperature environments. Summary of the Invention

[0003] In view of the above-mentioned deficiencies of the prior art, one object of the present invention is to provide a method for producing a high-temperature resistant lithium battery base film.

[0004] To solve the above problems, the technical solution of the present invention is: a method for producing a high-temperature resistant lithium battery base film, wherein the lithium battery base film is composed of PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product. The production method includes the following steps: (1) PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product are blended and fed into an extruder for compounding and plasticizing. (2) The molten melt is fed into the die head, and the melt forms a molten sheet through the flat die head opening; (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Spray a phytic acid / cysteine ​​coating onto the film surface; (6) Wind up the film.

[0005] Further, the preparation method of the DOPO-triglycidyl-p-aminophenol reaction product is as follows: Xylene solution is added to a container, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is dissolved in xylene, stirred and heated to 120 °C under nitrogen protection, triglycidyl-p-aminophenol is dissolved in an appropriate amount of xylene, reacted for 30 min, the pale yellow precipitate is filtered, and unreacted matter is removed with ethyl acetate. The product is dried in a vacuum drying oven at 70 °C for 10 h to obtain the DOPO-triglycidyl-p-aminophenol reaction product.

[0006] Furthermore, the preparation method of the phytic acid / cysteine ​​coating is as follows: phytic acid, cysteine ​​solution and deionized water are added to a reactor in a mass ratio of 9:1:40 to prepare a phytic acid / cysteine ​​solution. The phytic acid / cysteine ​​solution is sprayed onto the surface of the film and dried at 80 °C to obtain the phytic acid / cysteine ​​coating.

[0007] Furthermore, the components of the lithium battery base film are as follows by mass ratio: PA6 40%, PA10T / 66 15.5%, magnesium hydroxide 10%, glass fiber 10%, zinc borate 1%, antioxidant 0.5%, silane coupling agent modified silica 20%, and DOPO-triglycidyl-p-aminophenol reaction product 3%.

[0008] The beneficial effects of this invention are as follows: the addition of glass fiber increases the tensile strength, flexural strength, and flexural modulus of the composite material with increasing glass fiber content; magnesium hydroxide and zinc borate, as flame retardants, can improve the flame retardant properties of the material; the addition of a small amount of zinc borate can also improve the comprehensive mechanical properties of the composite material, increasing elongation at break, unnotched impact strength, and flexural modulus; the toughness and chemical resistance of PA6 can be combined with the high strength and heat resistance of PA10T / 66 to form a material with better overall performance; the mixed material may have both good processability and stable performance at high temperatures; silica, as a thermally conductive filler, can increase the thermal conductivity of the material and raise the heat distortion temperature; the addition of a small amount of DOPO-triglycidyl-p-aminophenol reaction product improves the thermal conductivity, heat distortion temperature, and mechanical properties of the composite material; and the phytic acid / cysteine ​​coating can significantly improve the thermal stability and flame retardant properties of the film. Detailed Implementation

[0009] To provide a more intuitive and complete understanding of the technical solution of this invention, the following non-limiting features are described: A method for producing a high-temperature resistant lithium battery base film, wherein the lithium battery base film is composed of PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product. The production method of high-temperature resistant lithium battery base film includes the following steps: (1) PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product are blended and fed into an extruder for compounding and plasticizing. (2) The molten melt is fed into the die head, and the melt forms a molten sheet through the flat die head opening; (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Spray a phytic acid / cysteine ​​coating onto the film surface; (6) Wind up the film.

[0010] The preparation method of DOPO-triglycidyl-p-aminophenol reaction product is as follows: Xylene solution is added to a container, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is dissolved in xylene. Under nitrogen protection, the mixture is stirred and heated to 120 °C. Triglycidyl-p-aminophenol is dissolved in an appropriate amount of xylene. The molar ratio of triglycidyl-p-aminophenol to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1. The reaction is carried out for 30 min. The pale yellow precipitate is filtered, and unreacted substances are removed with ethyl acetate. The product is dried in a vacuum drying oven at 70 °C for 10 h to obtain DOPO-triglycidyl-p-aminophenol reaction product.

[0011] The preparation method of phytic acid / cysteine ​​coating is as follows: phytic acid, cysteine ​​solution and deionized water are added to a reactor in a mass ratio of 9:1:40 to prepare phytic acid / cysteine ​​solution. The phytic acid / cysteine ​​solution is sprayed onto the surface of the film and dried at 80 °C to obtain phytic acid / cysteine ​​coating.

[0012] The components of the lithium battery base film, by mass ratio, are: PA6 40%, PA10T / 66 15.5%, magnesium hydroxide 10%, glass fiber 10%, zinc borate 1%, antioxidant 0.5%, silane coupling agent modified silica 20%, and DOPO-triglycidyl-p-aminophenol reaction product 3%. The antioxidant is antioxidant 1010. The silane coupling agent modified silica uses KH550 silane coupling agent.

[0013] The addition of glass fiber increases the tensile strength, flexural strength, and flexural modulus of the composite material. Magnesium hydroxide and zinc borate, as flame retardants, can improve the flame retardant properties of the material. The addition of a small amount of zinc borate can also improve the comprehensive mechanical properties of the composite material, increasing elongation at break, unnotched impact strength, and flexural modulus. The toughness and chemical resistance of PA6 can be combined with the high strength and heat resistance of PA10T / 66 to form a material with better overall performance. The blended material may have both good processability and stable performance at high temperatures. Silica, as a thermally conductive filler, can increase the thermal conductivity of the material and raise the heat distortion temperature. The addition of a small amount of DOPO-triglycidyl-p-aminophenol reaction product improves the thermal conductivity, heat distortion temperature, and mechanical properties of the composite material.

[0014] The epoxy groups in the DOPO-triglycidyl-p-aminophenol reaction product react chemically with the terminal hydroxyl groups of PA6 and the amino groups of KH550 silane coupling agent-modified silica, acting as a bridge between PA6 and KH550 silane coupling agent-modified silica. This enhances the interfacial interaction between PA6 and KH550 silane coupling agent-modified silica, thereby further improving the thermal conductivity of the composite material. Triglycidyl-p-aminophenol itself has high heat resistance, and its addition can significantly improve the heat resistance temperature of PA6 composite materials. At high temperatures, triglycidyl-p-aminophenol maintains a stable chemical structure and is not easily decomposed or volatilized, thus effectively preventing the thermal deformation of the PA6 matrix. The epoxy groups in the DOPO-triglycidyl-p-aminophenol reaction product may undergo cross-linking reactions with the amino and other functional groups on the PA6 molecular chain, forming a more stable cross-linking network. This cross-linking network can restrict the movement of PA6 molecular chains at high temperatures, increasing the heat distortion temperature of the composite material. Triglycidyl-p-aminophenol, as a rigid molecule, can enhance the rigidity and strength of PA6 composite materials to a certain extent when added. This enhancement helps to improve the mechanical properties of composite materials, such as tensile strength and flexural strength.

[0015] Phytic acid / cysteine ​​coatings significantly improve the thermal stability and flame retardant properties of thin films. Phytic acid, a bio-based material, is mainly found in the seeds, roots, and stems of plants. Its molecular structure contains a high content of the flame-retardant element phosphorus (possessing six negatively charged phosphate groups linked to twelve hydroxyl groups that can hydrolyze into hydrogen ions). During combustion, these phosphorus elements form a phosphate coating layer, isolating oxygen and inhibiting flame spread, thereby improving the material's flame retardant properties. Under acidic conditions, phytic acid can chelate with metal cations to form stable, non-hydrolyzable complexes. This chemical stability helps maintain the integrity of the coating during combustion, further enhancing the flame-retardant effect. Cysteine, an amino acid containing sulfur atoms, may produce a synergistic effect when blended with phytic acid due to its unique molecular structure. Sulfur atoms can form sulfur-containing compounds during combustion, which also have flame-retardant properties, further improving the coating's flame-retardant performance. The introduction of cysteine ​​may alter the coating's microstructure, making it more stable at high temperatures and less prone to decomposition or melting, thus improving the film's thermal stability. The phytic acid / cysteine ​​blend coating forms a dense protective layer on the PA film surface. This protective layer not only has flame-retardant properties but also isolates heat and oxygen transfer, thereby slowing down the film's heating rate and improving its thermal stability. During combustion, the flame-retardant elements and groups of phytic acid and cysteine ​​can undergo chemical reactions to generate flame-retardant compounds. These compounds can inhibit the spread of flames and the generation of smoke, thus protecting the film from further damage.

Claims

1. A method for producing a high-temperature resistant lithium battery base film, characterized in that: The lithium battery base film is composed of PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product. The production method includes the following steps: (1) PA6, PA10T / 66, magnesium hydroxide, glass fiber, zinc borate, antioxidant, silane coupling agent modified silica, and DOPO-triglycidyl-p-aminophenol reaction product are blended and fed into an extruder for compounding and plasticizing. (2) The molten melt is fed into the die head, and the melt forms a molten sheet through the flat die head opening; (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Spray a phytic acid / cysteine ​​coating onto the film surface; (6) Wind up the film.

2. The method for producing a high-temperature resistant lithium battery base film according to claim 1, characterized in that: The preparation method of DOPO-triglycidyl-p-aminophenol reaction product is as follows: Xylene solution is added to a container, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is dissolved in xylene. Under nitrogen protection, the mixture is stirred and heated to 120 °C. Triglycidyl-p-aminophenol is dissolved in an appropriate amount of xylene. The reaction is carried out for 30 min. The pale yellow precipitate is filtered, and unreacted substances are removed with ethyl acetate. The precipitate is dried in a vacuum drying oven at 70 °C for 10 h to obtain DOPO-triglycidyl-p-aminophenol reaction product.

3. The method for producing a high-temperature resistant lithium battery base film according to claim 1, characterized in that: The preparation method of phytic acid / cysteine ​​coating is as follows: phytic acid, cysteine ​​solution and deionized water are added to a reactor in a mass ratio of 9:1:40 to prepare phytic acid / cysteine ​​solution. The phytic acid / cysteine ​​solution is sprayed onto the surface of the film and dried at 80 °C to obtain phytic acid / cysteine ​​coating.

4. The method for producing a high-temperature resistant lithium battery base film according to claim 1, characterized in that: The components of the lithium battery base film by mass ratio are: PA6 40%, PA10T / 66 15.5%, magnesium hydroxide 10%, glass fiber 10%, zinc borate 1%, antioxidant 0.5%, silane coupling agent modified silica 20%, and DOPO-triglycidyl-p-aminophenol reaction product 3%.