Fireproof coating for new energy vehicle power battery pack and preparation method thereof

Abstract

This invention discloses a fire-retardant coating for power battery packs of new energy vehicles and its preparation method, relating to the field of fire-retardant coating preparation technology. The coating includes the following raw materials: functional agent A, functional agent B, flame retardant, acrylic-polyurethane copolymer resin, fluorinated acrylate, polyurethane microspheres, dispersant, antioxidant, polyether-modified polysiloxane, hollow glass microspheres, boron nitride, film-forming aid, and deionized water. The invention adds a flame retardant, in which ammonium polyphosphate decomposes as an acid source to produce phosphoric acid, catalyzing the dehydration of pentaerythritol to form char. Melamine and urea release ammonia gas to support the expansion of the char layer, forming a dense, expanded char layer. This solves the defect of loose char layers in traditional flame-retardant systems, ensuring stable and consistent flame-retardant effects and significantly improving the coating's fire resistance time. The added functional agents A and B can work synergistically to enhance the compatibility between inorganic components and prevent the thermal insulation layer from collapsing at high temperatures.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating preparation technology, and in particular to fire-retardant coatings for power battery packs of new energy vehicles and their preparation methods. Background Technology

[0002] Paint is a material that can be applied to the surface of an object and form a firmly adhered continuous film. It usually exists in the form of liquid, powder, etc., and after drying, it forms a solid protective film with specific functions.

[0003] Traditional fire-retardant coatings suffer from loose char layers, high-temperature insulation failure, and insufficient fire resistance. Furthermore, these coatings have weak resistance to electrolyte corrosion, are prone to powdering and discoloration with long-term use, and tend to separate, settle, and agglomerate during storage. Therefore, this invention provides a fire-retardant coating for power battery packs in new energy vehicles and its preparation method. Summary of the Invention

[0004] The main objective of this invention is to provide a fire-retardant coating with good fire resistance and high stability, which is applied to the fire-retardant coating of power battery packs for new energy vehicles and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a fire-retardant coating for power battery packs of new energy vehicles. The fire-retardant coating comprises the following raw materials: 13.5-15 parts of functional agent A, 7.5-8.5 parts of functional agent B, 36-38 parts of flame retardant, 22-24 parts of acrylic-polyurethane copolymer resin, 4.5-5.5 parts of fluorinated acrylate, 1.8-2.2 parts of polyurethane microspheres, 0.6-0.8 parts of dispersant, 0.25-0.35 parts of antioxidant, 0.15-0.25 parts of polyether-modified polysiloxane, 5.5-6.5 parts of hollow glass microspheres, 0.8-1.5 parts of boron nitride, 0.4-0.6 parts of film-forming aid, and 1.8-2.2 parts of deionized water; The acrylic-polyurethane copolymer resin has a solid content of 40±2%, a VOC content of ≤10g / L, and a hydroxyl value of 50-70mgKOH / g. Fluorine-modified acrylate has a fluorine content of 8-10%, a VOC content of ≤5g / L, a surface tension of ≤30mN / m, and a solid content of 50±2%. As a special component for electrolyte resistance, its hydrophobic and anti-permeability properties can form a dense barrier on the coating surface, effectively preventing the battery electrolyte from penetrating and avoiding coating blistering and cracking caused by electrolyte erosion. It has good compatibility with the resin system, does not affect other properties of the coating, significantly improves the durability of the coating in the complex environment of the battery pack, and ensures that the flame retardant performance does not significantly decrease after long-term use. Polyether-modified polysiloxanes can reduce the surface tension of coatings, promote the formation of a smooth and flat surface during the drying process, and avoid orange peel defects. The hollow glass microspheres have a particle size of 50-100 μm; Polyurethane microspheres with a particle size of 1-3μm are dispersed inside the coating, which can effectively absorb vibration energy, inhibit the generation and propagation of microcracks, and work synergistically with acrylic-polyurethane copolymer resin to improve the flexibility of the coating, further enhance the coating's resistance to peeling and cracking, adapt to the vibration conditions of the battery pack during driving, and ensure the long-term stability of the coating structure. The preparation of the flame retardant includes the following steps: adding ammonium polyphosphate, melamine, pentaerythritol and urea into a high-speed mixer and stirring at 3000 rpm for 5-7 minutes to obtain the flame retardant.

[0006] Furthermore, the mass ratio of ammonium polyphosphate, melamine, pentaerythritol, and urea in the flame retardant is 12.25:3.5:1.75:1.

[0007] Ammonium polyphosphate has a phosphorus content ≥31%, a nitrogen content ≥14%, a particle size of 10-20 μm, and a moisture content ≤0.2%; melamine has a particle size of 5-10 μm, a purity ≥99.5%, and a moisture content ≤0.1%; pentaerythritol has a particle size of 8-15 μm, a purity ≥99%, and a moisture content ≤0.2%; urea has a particle size of 5-10 μm, a purity ≥99.8%, and a moisture content ≤0.1%. Further, the preparation of the functional agent A includes the following steps: adding nano-silica and deionized water into a reaction vessel and stirring at a speed of 60-80 rpm for 3 minutes; adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and dispersing using an ultrasonic disperser at a power of 400W and a temperature of 25°C for 25 minutes to obtain functional agent A.

[0008] Furthermore, the mass ratio of the nano-silica, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and deionized water is 20:1:26.7.

[0009] The nano-silica has a particle size of 20-50 nm, a purity of ≥99.8%, and a moisture content of ≤0.5%. Furthermore, the functional agent B is a mixture of modified montmorillonite, COF microspheres, and acrylic-polyurethane copolymer resin; The mass ratio of the modified montmorillonite, acrylic-polyurethane copolymer resin, and COF microspheres is 3:5:1.

[0010] The modifier for modified montmorillonite is hexadecyltrimethylammonium bromide, and the particle size of the modified montmorillonite is ≤2μm with a moisture content ≤1.0%. The COF microspheres have a particle size of 100-200 nm and a purity of ≥95%. Furthermore, the dispersant is a mixture of sodium polymethacrylate and fatty alcohol polyoxyethylene ether phosphate; The mass ratio of sodium polymethacrylate to fatty alcohol polyoxyethylene ether phosphate is 2:1.

[0011] Furthermore, the film-forming aid is a mixture of propylene glycol butyl ether and ethylene glycol hexyl ether; The mass ratio of propylene glycol butyl ether to ethylene glycol hexyl ether is 1:1.

[0012] Film-forming aids can temporarily plasticize resin particles, promoting their fusion during film formation and making the coating denser and smoother.

[0013] Further, the antioxidant is a mixture of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; The mass ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] is 1:1.

[0014] In the antioxidant, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole absorbs ultraviolet light, preventing the resin from being degraded by ultraviolet light irradiation, while pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] can capture free radicals and prevent the resin from undergoing thermo-oxidative aging under the action of heat and oxygen.

[0015] Secondly, the present invention also provides a method for preparing a fire-retardant coating for a power battery pack for new energy vehicles, comprising the following preparation steps: S1. Add deionized water to the reactor and stir at 800 rpm. Add dispersant, polyether-modified polysiloxane and film-forming aid in sequence and stir for 8 minutes. Add antioxidant and stir for 5 minutes. Turn on the reactor wall scraping device and set the scraping device speed to 30 rpm. Add flame retardant in three batches with a 3-minute interval between each addition. After all the flame retardant has been added, stir for 15 minutes. Add functional agent B and stir at 800 rpm for 10 minutes. Add hollow glass microspheres and stir at 500 rpm for 8 minutes. Add boron nitride and stir for 5 minutes. Increase the speed to 1300 rpm and add functional agent A. Stir for 25 minutes to obtain a dispersion. S2. Add the dispersion to the sand mill, add zirconium oxide and grind, control the grinding temperature ≤30℃, speed 1500rpm, grind for 15 minutes, increase the speed to 2000rpm and grind for 25-30 minutes to obtain the slurry; S3. Add the slurry to the reactor and stir at 600 rpm. Add the acrylic-polyurethane copolymer resin in three batches, stirring 5 minutes apart. After all the resin is added, stir for 15 minutes. Add polyurethane microspheres and fluorinated acrylate and stir, increasing the speed to 8000 rpm and stirring for 20 minutes. Add a 5% (w / w) hydroxyethyl cellulose aqueous solution and stir for 10 minutes. Let stand for 30 minutes. Filter the mixture through 180-mesh and 300-mesh filters to remove particulate impurities, obtaining the fireproof coating for the power battery pack of new energy vehicles.

[0016] Fluorinated acrylates and acrylic-polyurethane copolymers can work synergistically. The hydrophobic and anti-permeation properties of the fluorinated acrylates work in synergy with the adhesive properties of the resin, improving their compatibility. After the resin forms a film, the fluorinated acrylates create a hydrophobic barrier on the surface. The resin ensures that the barrier is tightly bonded to the coating substrate, synergistically preventing the penetration of battery electrolyte and avoiding coating blistering and cracking, while not affecting the mechanical properties of the coating. This significantly improves the durability of the coating in the complex environment of the battery pack. Furthermore, the mass ratio of the dispersion to zirconium oxide in S2 is 1:3-5; The zirconium oxide has a particle size of 0.3-0.5 mm; In step S3, a 5% (w / w) aqueous solution of hydroxyethyl cellulose is added to adjust the viscosity to 6000-7000 mPa·s.

[0017] The present invention has the following beneficial effects: 1. In this invention, a flame retardant is added. The ammonium polyphosphate in the flame retardant decomposes as an acid source to produce phosphoric acid, which catalyzes the dehydration of pentaerythritol to form char. Melamine and urea release ammonia gas to support the expansion of the char layer, forming a dense and expanded char layer. This solves the defect of loose char layer in traditional flame retardant systems, ensures stable and consistent flame retardant effect, and significantly improves the fire resistance time of the coating.

[0018] 2. In this invention, the addition of functional agent A and functional agent B can synergistically construct a dual thermal insulation system with nano-filled sheet barrier. The nano-silica in functional agent A fills the gaps between the modified montmorillonite sheets, filling the pores of the coating. The modified montmorillonite sheets delay the lateral heat transfer and synergistically improve the high-temperature thermal insulation density, resulting in a high retention rate of thermal insulation effect at 800℃. It also enhances the compatibility between inorganic components and prevents the thermal insulation layer from collapsing at high temperatures. The COF microspheres and modified montmorillonite synergistically strengthen the interfacial bonding between inorganic particles and resin, thereby improving the retention rate of high-temperature thermal insulation effect and significantly enhancing the density of the coating.

[0019] 3. In this invention, hollow glass microspheres and boron nitride work synergistically. The hollow glass microspheres balance the density of the system and inhibit filler sedimentation, while the boron nitride maintains structural stability at high temperatures. Together, they construct a lightweight and high-temperature resistant dual protection, ensuring the coating is lightweight and preventing the insulation layer from failing at high temperatures, thus improving the overall adaptability of the fireproof coating. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that all raw materials used in the following experiments are commercially available.

[0022] Example 1: A fire-retardant coating for a power battery pack in a new energy vehicle. The fire-retardant coating comprises the following raw materials: 13.5 parts functional agent A, 7.5 parts functional agent B, 36 parts flame retardant, 22 parts acrylic-polyurethane copolymer resin, 4.5 parts fluorinated modified acrylate, 1.8 parts polyurethane microspheres, 0.6 parts dispersant, 0.25 parts antioxidant, 0.15 parts polyether modified polysiloxane, 5.5 parts hollow glass microspheres, 0.8-1.5 parts boron nitride, 0.4 parts film-forming aid, and 1.8 parts deionized water. The preparation of flame retardant includes the following steps: adding ammonium polyphosphate, melamine, pentaerythritol and urea into a high-speed mixer and stirring at 3000 rpm for 5-7 minutes to obtain the flame retardant.

[0023] The mass ratio of ammonium polyphosphate, melamine, pentaerythritol and urea in the flame retardant is 12.25:3.5:1.75:1.

[0024] The preparation of functional agent A includes the following steps: nano-silica and deionized water are added to a reaction vessel and stirred at a speed of 60-80 rpm for 3 minutes. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added and dispersed using an ultrasonic disperser at a power of 400W and a temperature of 25℃ for 25 minutes to obtain functional agent A.

[0025] The mass ratio of nano-silica, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and deionized water is 20:1:26.7.

[0026] Functional agent B is a mixture of modified montmorillonite, COF microspheres, and acrylic-polyurethane copolymer resin; The mass ratio of modified montmorillonite, acrylic-polyurethane copolymer resin and COF microspheres is 3:5:1.

[0027] The dispersant is a mixture of sodium polymethacrylate and fatty alcohol polyoxyethylene ether phosphate; The mass ratio of sodium polymethacrylate to fatty alcohol polyoxyethylene ether phosphate is 2:1.

[0028] The film-forming aid is a mixture of propylene glycol butyl ether and ethylene glycol hexyl ether; The mass ratio of propylene glycol butyl ether to ethylene glycol hexyl ether is 1:1.

[0029] The antioxidant is a mixture of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]; The mass ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] was 1:1.

[0030] Secondly, the present invention also provides a method for preparing a fire-retardant coating for a power battery pack for new energy vehicles, comprising the following preparation steps: S1. Add deionized water to the reactor and stir at 800 rpm. Add dispersant, polyether-modified polysiloxane and film-forming aid in sequence and stir for 8 minutes. Add antioxidant and stir for 5 minutes. Turn on the reactor wall scraping device and set the scraping device speed to 30 rpm. Add flame retardant in three batches with a 3-minute interval between each addition. After all the flame retardant has been added, stir for 15 minutes. Add functional agent B and stir at 800 rpm for 10 minutes. Add hollow glass microspheres and stir at 500 rpm for 8 minutes. Add boron nitride and stir for 5 minutes. Increase the speed to 1300 rpm and add functional agent A. Stir for 25 minutes to obtain a dispersion. S2. Add the dispersion to the sand mill, add zirconium oxide and grind, control the grinding temperature ≤30℃, speed 1500rpm, grind for 15 minutes, increase the speed to 2000rpm and grind for 25-30 minutes to obtain the slurry; S3. Add the slurry to the reactor and stir at 600 rpm. Add the acrylic-polyurethane copolymer resin in three batches, stirring 5 minutes apart. After all the resin is added, stir for 15 minutes. Add polyurethane microspheres and fluorinated acrylate and stir, increasing the speed to 8000 rpm and stirring for 20 minutes. Add a 5% (w / w) hydroxyethyl cellulose aqueous solution and stir for 10 minutes. Let stand for 30 minutes. Filter the mixture through 180-mesh and 300-mesh filters to remove particulate impurities, obtaining the fireproof coating for the power battery pack of new energy vehicles.

[0031] The mass ratio of dispersion to zirconium oxide in S2 is 1:3-5; The particle size of zirconium oxide is 0.3-0.5 mm; Add a 5% (w / w) aqueous solution of hydroxyethyl cellulose to S3 to adjust the viscosity to 6000-7000 mPa·s.

[0032] Example 2: A fire-retardant coating for a power battery pack in a new energy vehicle. The fire-retardant coating comprises the following raw materials: 14.2 parts functional agent A, 8 parts functional agent B, 37 parts flame retardant, 23 parts acrylic-polyurethane copolymer resin, 5 parts fluorinated modified acrylate, 2 parts polyurethane microspheres, 0.7 parts dispersant, 0.3 parts antioxidant, 0.2 parts polyether modified polysiloxane, 6 parts hollow glass microspheres, 1.1 parts boron nitride, 0.5 parts film-forming aid, and 2 parts deionized water. The preparation of flame retardant includes the following steps: adding ammonium polyphosphate, melamine, pentaerythritol and urea into a high-speed mixer and stirring at 3000 rpm for 5-7 minutes to obtain the flame retardant.

[0033] The mass ratio of ammonium polyphosphate, melamine, pentaerythritol and urea in the flame retardant is 12.25:3.5:1.75:1.

[0034] The preparation of functional agent A includes the following steps: nano-silica and deionized water are added to a reaction vessel and stirred at a speed of 60-80 rpm for 3 minutes. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added and dispersed using an ultrasonic disperser at a power of 400W and a temperature of 25℃ for 25 minutes to obtain functional agent A.

[0035] The mass ratio of nano-silica, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and deionized water is 20:1:26.7.

[0036] Functional agent B is a mixture of modified montmorillonite, COF microspheres, and acrylic-polyurethane copolymer resin; The mass ratio of modified montmorillonite, acrylic-polyurethane copolymer resin and COF microspheres is 3:5:1.

[0037] The dispersant is a mixture of sodium polymethacrylate and fatty alcohol polyoxyethylene ether phosphate; The mass ratio of sodium polymethacrylate to fatty alcohol polyoxyethylene ether phosphate is 2:1.

[0038] The film-forming aid is a mixture of propylene glycol butyl ether and ethylene glycol hexyl ether; The mass ratio of propylene glycol butyl ether to ethylene glycol hexyl ether is 1:1.

[0039] The antioxidant is a mixture of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]; The mass ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] was 1:1.

[0040] Secondly, the present invention also provides a method for preparing a fire-retardant coating for a power battery pack for new energy vehicles, comprising the following preparation steps: S1. Add deionized water to the reactor and stir at 800 rpm. Add dispersant, polyether-modified polysiloxane and film-forming aid in sequence and stir for 8 minutes. Add antioxidant and stir for 5 minutes. Turn on the reactor wall scraping device and set the scraping device speed to 30 rpm. Add flame retardant in three batches with a 3-minute interval between each addition. After all the flame retardant has been added, stir for 15 minutes. Add functional agent B and stir at 800 rpm for 10 minutes. Add hollow glass microspheres and stir at 500 rpm for 8 minutes. Add boron nitride and stir for 5 minutes. Increase the speed to 1300 rpm and add functional agent A. Stir for 25 minutes to obtain a dispersion. S2. Add the dispersion to the sand mill, add zirconium oxide and grind, control the grinding temperature ≤30℃, speed 1500rpm, grind for 15 minutes, increase the speed to 2000rpm and grind for 25-30 minutes to obtain the slurry; S3. Add the slurry to the reactor and stir at 600 rpm. Add the acrylic-polyurethane copolymer resin in three batches, stirring 5 minutes apart. After all the resin is added, stir for 15 minutes. Add polyurethane microspheres and fluorinated acrylate and stir, increasing the speed to 8000 rpm and stirring for 20 minutes. Add a 5% (w / w) hydroxyethyl cellulose aqueous solution and stir for 10 minutes. Let stand for 30 minutes. Filter the mixture through 180-mesh and 300-mesh filters to remove particulate impurities, obtaining the fireproof coating for the power battery pack of new energy vehicles.

[0041] The mass ratio of dispersion to zirconium oxide in S2 is 1:3-5; The particle size of zirconium oxide is 0.3-0.5 mm; Add a 5% (w / w) aqueous solution of hydroxyethyl cellulose to S3 to adjust the viscosity to 6000-7000 mPa·s.

[0042] Example 3: A fire-retardant coating for a power battery pack in a new energy vehicle. The fire-retardant coating comprises the following raw materials: 15 parts functional agent A, 8.5 parts functional agent B, 38 parts flame retardant, 24 parts acrylic-polyurethane copolymer resin, 5.5 parts fluorinated modified acrylate, 2.2 parts polyurethane microspheres, 0.8 parts dispersant, 0.35 parts antioxidant, 0.25 parts polyether modified polysiloxane, 6.5 parts hollow glass microspheres, 1.5 parts boron nitride, 0.6 parts film-forming aid, and 2.2 parts deionized water. The preparation of flame retardant includes the following steps: adding ammonium polyphosphate, melamine, pentaerythritol and urea into a high-speed mixer and stirring at 3000 rpm for 5-7 minutes to obtain the flame retardant.

[0043] The mass ratio of ammonium polyphosphate, melamine, pentaerythritol and urea in the flame retardant is 12.25:3.5:1.75:1.

[0044] The preparation of functional agent A includes the following steps: nano-silica and deionized water are added to a reaction vessel and stirred at a speed of 60-80 rpm for 3 minutes. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added and dispersed using an ultrasonic disperser at a power of 400W and a temperature of 25℃ for 25 minutes to obtain functional agent A.

[0045] The mass ratio of nano-silica, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and deionized water is 20:1:26.7.

[0046] Functional agent B is a mixture of modified montmorillonite, COF microspheres, and acrylic-polyurethane copolymer resin; The mass ratio of modified montmorillonite, acrylic-polyurethane copolymer resin and COF microspheres is 3:5:1.

[0047] The dispersant is a mixture of sodium polymethacrylate and fatty alcohol polyoxyethylene ether phosphate; The mass ratio of sodium polymethacrylate to fatty alcohol polyoxyethylene ether phosphate is 2:1.

[0048] The film-forming aid is a mixture of propylene glycol butyl ether and ethylene glycol hexyl ether; The mass ratio of propylene glycol butyl ether to ethylene glycol hexyl ether is 1:1.

[0049] The antioxidant is a mixture of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]; The mass ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] was 1:1.

[0050] Secondly, the present invention also provides a method for preparing a fire-retardant coating for a power battery pack for new energy vehicles, comprising the following preparation steps: S1. Add deionized water to the reactor and stir at 800 rpm. Add dispersant, polyether-modified polysiloxane and film-forming aid in sequence and stir for 8 minutes. Add antioxidant and stir for 5 minutes. Turn on the reactor wall scraping device and set the scraping device speed to 30 rpm. Add flame retardant in three batches with a 3-minute interval between each addition. After all the flame retardant has been added, stir for 15 minutes. Add functional agent B and stir at 800 rpm for 10 minutes. Add hollow glass microspheres and stir at 500 rpm for 8 minutes. Add boron nitride and stir for 5 minutes. Increase the speed to 1300 rpm and add functional agent A. Stir for 25 minutes to obtain a dispersion. S2. Add the dispersion to the sand mill, add zirconium oxide and grind, control the grinding temperature ≤30℃, speed 1500rpm, grind for 15 minutes, increase the speed to 2000rpm and grind for 25-30 minutes to obtain the slurry; S3. Add the slurry to the reactor and stir at 600 rpm. Add the acrylic-polyurethane copolymer resin in three batches, stirring 5 minutes apart. After all the resin is added, stir for 15 minutes. Add polyurethane microspheres and fluorinated acrylate and stir, increasing the speed to 8000 rpm and stirring for 20 minutes. Add a 5% (w / w) hydroxyethyl cellulose aqueous solution and stir for 10 minutes. Let stand for 30 minutes. Filter the mixture through 180-mesh and 300-mesh filters to remove particulate impurities, obtaining the fireproof coating for the power battery pack of new energy vehicles.

[0051] The mass ratio of dispersion to zirconium oxide in S2 is 1:3-5; The particle size of zirconium oxide is 0.3-0.5 mm; Add a 5% (w / w) aqueous solution of hydroxyethyl cellulose to S3 to adjust the viscosity to 6000-7000 mPa·s.

[0052] Comparative Example 1: The difference between this comparative example and Example 1 is that: This comparative example does not contain flame retardants.

[0053] Comparative Example 2: The difference between this comparative example and Example 1 is that: Polyurethane microspheres were not used in this comparative example.

[0054] Comparative Example 3 differs from Example 1 in that: This comparative example does not contain functional agent B.

[0055] Performance testing: The fire-retardant coatings prepared in Examples 1, 2, 3, 1, 2 and 3 were tested.

[0056] Performance testing: The relevant performance of the fire-retardant coatings and their preparation methods for new energy vehicle power battery packs provided in Examples 1-3 and Comparative Examples 1-3 were tested respectively, and the test data are recorded in Table 1 below:

[0057] Based on the above data, the following conclusions can be drawn: (1) The expansion ratio of Examples 1-3 at 600℃ is far superior to that of Comparative Examples 1-3. The key point is that the examples improve the expansion ratio of the coating at 600℃ by adding flame retardants, and by precisely increasing the expansion ratio of the coating at 600℃ through the addition of ammonium polyphosphate, melamine, pentaerythritol and urea in the flame retardants.

[0058] (2) The fact that the samples of Examples 1-3 did not separate after being stored at 15-30℃ for 6 months was far superior to that of Comparative Examples 1-3. The key point is that the examples added polyurethane microspheres, whose density was highly matched with the coating system, which reduced the settling rate of the filler. At the same time, the spherical structure formed a spatial steric hindrance, which, together with the double electric layer stabilizing effect of the dispersant, prevented the particles from agglomerating.

[0059] (3) The fact that Examples 1-3 did not crack after 50 cycles of -40℃ to 85℃ is far superior to Comparative Examples 1-3. The key point is that the Examples added functional agent B, and its monolayer structure can absorb the shrinkage and expansion stress generated by the cold and heat cycle through slippage, thus avoiding stress concentration. Its surface organic modified groups form chemical bonds with acrylic-polyurethane copolymer resin, thereby improving the interfacial bonding force.

[0060] Through the above demonstrations, the present invention is significantly superior to the control group in terms of expansion ratio at 600℃, no delamination after 6 months of storage at 15-30℃, and no cracking after 50 cycles at -40℃ to 85℃, thus verifying the advanced nature and rationality of the preparation process.

[0061] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fire-retardant coating for power battery packs of new energy vehicles, characterized in that, The fire-retardant coating comprises the following raw materials: 13.5-15 parts functional agent A, 7.5-8.5 parts functional agent B, 36-38 parts flame retardant, 22-24 parts acrylic-polyurethane copolymer resin, 4.5-5.5 parts fluorinated modified acrylate, 1.8-2.2 parts polyurethane microspheres, 0.6-0.8 parts dispersant, 0.25-0.35 parts antioxidant, 0.15-0.25 parts polyether modified polysiloxane, 5.5-6.5 parts hollow glass microspheres, 0.8-1.5 parts boron nitride, 0.4-0.6 parts film-forming aid, and 1.8-2.2 parts deionized water; The preparation of the flame retardant includes the following steps: adding ammonium polyphosphate, melamine, pentaerythritol and urea into a high-speed mixer and stirring to obtain the flame retardant; The mass ratio of ammonium polyphosphate, melamine, pentaerythritol, and urea in the flame retardant is 12.25:3.5:1.75:1; The preparation of the functional agent A includes the following steps: adding nano-silica and deionized water into a reaction vessel and stirring, adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and dispersing using an ultrasonic disperser to obtain functional agent A; The functional agent B is a mixture of modified montmorillonite, COF microspheres and acrylic-polyurethane copolymer resin; The mass ratio of the modified montmorillonite, acrylic-polyurethane copolymer resin, and COF microspheres is 3:5:

1.

2. The fire-retardant coating according to claim 1, characterized in that, The mass ratio of the nano-silica, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and deionized water is 20:1:26.

7.

3. The fire-retardant coating according to claim 1, characterized in that, The dispersant is a mixture of sodium polymethacrylate and fatty alcohol polyoxyethylene ether phosphate; The mass ratio of sodium polymethacrylate to fatty alcohol polyoxyethylene ether phosphate is 2:

1.

4. The fire-retardant coating according to claim 1, characterized in that, The film-forming aid is a mixture of propylene glycol butyl ether and ethylene glycol hexyl ether; The mass ratio of propylene glycol butyl ether to ethylene glycol hexyl ether is 1:

1.

5. The fire-retardant coating according to claim 1, characterized in that, The antioxidant is a mixture of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; The mass ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] is 1:

1.

6. A method for preparing a fire-retardant coating for a power battery pack of new energy vehicles, comprising the fire-retardant coating according to any one of claims 1-5, characterized in that, The preparation steps include the following: S1. Add deionized water to the reactor and stir. Then add dispersant, polyether-modified polysiloxane and film-forming aid in sequence and stir. Add antioxidant and stir. Add flame retardant in three batches and stir. Add functional agent B and stir. Add hollow glass microspheres and stir. Add boron nitride and stir. Add functional agent A and stir to obtain a dispersion. S2. Add the dispersion to a sand mill, add zirconium oxide and grind to obtain a slurry; S3. Add the slurry into the reactor and stir. Add the acrylic-polyurethane copolymer resin in three batches and stir. Add the polyurethane microspheres and fluorinated acrylate and stir. Add the 5% (w / w) hydroxyethyl cellulose aqueous solution and stir. Filter the mixture through 180 mesh and 300 mesh filters in sequence to remove particulate impurities and obtain the fireproof coating for the power battery pack of new energy vehicles. The mass ratio of the dispersion to zirconium oxide in S2 is 1:3-5.

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