PP-glass fiber composite new energy automobile battery shell and preparation method thereof

Abstract

The invention discloses a PP-glass fiber composite new energy automobile battery shell and a preparation method thereof, belongs to the technical field of PP material processing, and aims to solve the technical problem that the flame retardance, impact resistance and high-temperature stability of a battery shell material in the prior art need to be further improved. The PP-glass fiber composite new energy automobile battery shell is formed by alternately overlapping a plurality of activated glass fiber mats and composite PP and then carrying out hot-pressing composite molding; according to the invention, through organic combination of interface activation, block copolymerization and a multi-element synergistic flame retardant technology, the impact toughness, high-temperature stability and flame retardant property of the PP-glass fiber composite material are remarkably improved, so that the safety and structural performance of a new energy automobile battery shell are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of PP material processing technology, specifically to a PP-glass fiber composite new energy vehicle battery casing and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the power battery system, as the core component of electric vehicles, has received widespread attention for its safety, lightweighting, and durability. As an important structural component of the battery module, the power battery casing not only undertakes the functions of supporting, sealing, and protecting the battery module, but also directly relates to the safety performance and energy density of the entire vehicle.

[0003] Currently, the materials used for the outer casing of new energy vehicle batteries are mainly divided into two categories: metal and non-metal composite materials. Although metal casings have excellent mechanical strength and flame retardancy, they are heavy, which is not conducive to the overall vehicle weight reduction to improve driving range. They also have problems such as easy corrosion and high production costs. Polypropylene (PP) based composite materials are considered to be potential alternatives to metal casings due to their advantages such as light weight, chemical corrosion resistance, good processability and low cost.

[0004] Currently, ordinary PP materials have low rigidity and heat resistance, making them prone to brittle fracture under external impact. They also have poor combustion performance, failing to meet the comprehensive requirements of high mechanical properties, high flame retardancy, and thermal stability for new energy vehicle battery shells. To improve the mechanical properties of PP-based materials, glass fiber reinforcement is usually used. The high strength and high modulus of glass fiber improve the rigidity and dimensional stability of PP. However, since the surface of glass fiber is an inert silicon-oxygen structure, it has poor interfacial compatibility with the non-polar PP matrix, resulting in weak interfacial adhesion. Under external impact or thermal cycling, interfacial debonding or interlayer peeling is likely to occur, affecting the overall mechanical properties and structural stability of the material. To improve the interfacial bonding between PP and glass fiber, methods such as modifying glass fiber with coupling agents are generally used. Although this improves interfacial adhesion to some extent, the modification effect is limited, and it is difficult to simultaneously achieve both impact toughness and flame retardancy of the material. On the other hand, although high-efficiency halogen-free flame retardants such as DOPO perform well in gas-phase flame retardancy, they have poor compatibility with the PP matrix, are prone to migration and precipitation, and contribute little to the strength of the char layer formed after combustion, resulting in decreased flame retardancy efficiency and insufficient durability. The fire safety and flame retardancy of the battery casing need to be further improved. Summary of the Invention

[0005] The purpose of this invention is to provide a PP-glass fiber composite battery shell for new energy vehicles and its preparation method, which solves the technical problem that the flame retardancy, impact resistance and high temperature stability of PP-glass fiber composite battery shell materials for new energy vehicles need to be further improved in the prior art.

[0006] The objective of this invention can be achieved through the following technical solution: a PP-glass fiber composite new energy vehicle battery shell, wherein the PP-glass fiber composite new energy vehicle battery shell is formed by hot pressing and bonding several activated glass fiber mats and composite PP alternately stacked; The method for preparing the activated glass fiber mat is as follows: the surface of the supported glass fiber mat loaded with iron and zinc oxides is modified by using an activation modification liquid containing γ-aminopropyltriethoxysilane to obtain the activated glass fiber mat. The composite PP comprises the following components by weight: 60-68 parts PP, 30-35 parts MAH-g-PP, 20-26 parts siloxane block polyurethane, 15-19 parts flame retardant, and 3-5 parts auxiliary additives, wherein the flame retardant is obtained by mixing Al-DOPO composite particles and melamine cyanurate in a weight ratio of 3:1.

[0007] Furthermore, the activated glass fiber mat is obtained by the following steps: A1. Completely immerse the glass fiber mat in the pretreatment solution, heat the pretreatment solution to 50-60℃, and sonicate for 30-50 minutes. Remove the glass fiber mat from the pretreatment solution, wash it with purified water until neutral, and air dry it to obtain the pretreated glass fiber mat. A2. Immerse the pretreated glass fiber mat in the mixed solution, keeping it completely submerged, and ultrasonically disperse it for 30-50 minutes. Transfer the reaction system to a high-pressure reactor at a temperature of 118-123℃, keep it at the temperature for 4-6 hours, and then perform post-treatment to obtain the loaded glass fiber mat. A3. Spray the activation and modification liquid evenly onto the load-bearing glass fiber mat, and then perform post-treatment to obtain the activated glass fiber mat.

[0008] Furthermore, in step A1, the pretreatment solution is obtained by mixing 6-8 mol / L sulfuric acid and 20 wt% hydrogen peroxide at a volume ratio of 6:1.

[0009] Further, in step A2, the mixed solution is obtained by mixing and dissolving ferric nitrate, zinc nitrate, urea, and purified water in a ratio of 5-7g:4-6g:10g:60mL. The ratio of the pretreated glass fiber mat to the mixed solution is 1g:5mL. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, the glass fiber mat is taken out of the solution, washed three times with purified water, and then transferred to a drying oven at 80-90℃ to dry to constant weight. Then it is transferred to a muffle furnace at 350-370℃ and calcined for 3-4 hours to obtain the supported glass fiber mat.

[0010] Further, in step A3, the spraying amount of the activation and modification liquid is 2-3 mL / cm2. The activation and modification liquid is composed of γ-aminopropyltriethoxysilane and ethanol solution in a volume ratio of 1 g: 4-5 mL. The ethanol solution is composed of anhydrous ethanol and 2-3 mol / L sodium hydroxide aqueous solution in a volume ratio of 9:1. The post-treatment includes: after the activation and modification liquid is sprayed, it is transferred to a drying oven at a temperature of 60-70℃ and dried to constant weight to obtain activated glass fiber mat.

[0011] Furthermore, the preparation method of Al-DOPO composite particles is as follows: DOPO, nano-alumina, anhydrous ethanol and sodium dodecyl sulfate are mixed, the reaction system temperature is raised to 50-60℃, ultrasonically dispersed for 30-50 min, the reaction system temperature is lowered to 23-28℃, purified water is added to the reaction system, and the mixture is stirred for 60-80 min. Acetic acid is added to the reaction system to adjust the pH of the system to 3-4. A silicic acid mixture is added to the reaction system, the reaction system temperature is raised to 78-82℃, and the mixture is kept at this temperature and stirred for 3-5 h. After post-treatment, Al-DOPO composite particles are obtained.

[0012] Furthermore, the ratio of DOPO, nano-alumina, anhydrous ethanol, sodium dodecyl sulfate, purified water, and silicic acid mixture is 2-3g:5g:20mL:0.6-0.8g:300mL:30g. The silicic acid mixture is composed of 10wt% sodium silicate aqueous solution and γ-glycidoxypropyltrimethoxysilane in a weight ratio of 30:0.6-0.8. The post-treatment includes: after the reaction is completed, the reaction system temperature is lowered to room temperature, filtered, the filter cake is washed three times with purified water and anhydrous ethanol and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80℃ and dried to constant weight to obtain Al-DOPO composite particles.

[0013] Furthermore, the preparation method of siloxane block polyurethane is as follows: under inert gas protection, polytetrahydrofuran ether diol, hydroxyl silicone oil, catalyst and toluene are mixed and stirred, the temperature of the reaction system is raised to 60-70℃, isophorone diisocyanate is added to the reaction system, the reaction is kept at the temperature for 40-50 min, a chain extender is added to the reaction system, the reaction is kept at the temperature for 30-50 min, an end-capping agent is added to the reaction system, the reaction is kept at the temperature for 50-60 min, and after post-treatment, siloxane block polyurethane is obtained.

[0014] The synthesis reaction formula for siloxane block polyurethane is as follows: In the formula: ; ; ; .

[0015] Furthermore, the ratio of polytetrahydrofuran ether diol, hydroxyl silicone oil, catalyst, toluene, chain extender, and end-capping agent is 2.9-3.1g:4.8-5.2g:0.01g:20mL:0.5g:2g. The catalyst is dibutyltin dilaurate. The molar amount of isophorone diisocyanate is 0.55 times the total molar amount of hydroxyl groups in the mixture of polytetrahydrofuran ether diol and hydroxyl silicone oil. The chain extender is 2-(aminomethyl)propane-1,3-diamine. The end-capping agent is glycidyl ether. The post-treatment includes: after the reaction is complete, the temperature of the reaction system is raised to 80°C, the negative pressure is reduced to -0.1MPa, the low-boiling substances are removed by vacuum evaporation, the material is discharged while hot, cooled and solidified, and pelletized to obtain siloxane block polyurethane.

[0016] Furthermore, the preparation method of MAH-g-PP is as follows: PP, styrene, and maleic anhydride are added to a torque rheometer at a temperature of 180-190℃ and mixed for 3-5 minutes. An initiator is added to the torque rheometer and mixed for 8-12 minutes. The torque rheometer is cooled to room temperature, and the material is discharged and pelletized to obtain MAH-g-PP.

[0017] Furthermore, the weight ratio of PP, styrene, maleic anhydride and initiator is 100:1:2.8-3.2:0.03, the torque rheometer speed is 60-70 r / min, and the initiator is dicumyl peroxide.

[0018] This invention also proposes a method for preparing a PP-glass fiber composite battery casing for new energy vehicles, comprising the following steps: S1. After mixing PP, MAH-g-PP, siloxane block polyurethane, flame retardant and auxiliary additives, the mixture is added to a twin-screw extruder and melt-mixed for 2-3 minutes. The mixture is then extruded through a die to obtain composite PP. S2. Three composite PP sheets and two activated glass fiber mats are alternately stacked and then placed in a hot press at a temperature of 180-190℃ and a pressure of 5-7MPa. After hot pressing for 4-7 minutes, the temperature is naturally cooled to room temperature to obtain the PP-glass fiber composite new energy vehicle battery shell.

[0019] Furthermore, the auxiliary additives are composed of plasticizer, dispersant, lubricant and antioxidant in a weight ratio of 5:2:1:1. The plasticizer is phthalate, the dispersant is stearate, the lubricant is ethylene bisoleamide, and the antioxidant is either antioxidant 1010 or antioxidant 1076. The temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end are 170°C, 170°C, 170°C and 180°C, respectively, and the spindle speed of the twin-screw extruder is 15-18 r / min.

[0020] The present invention has the following beneficial effects: This invention involves hot-pressing activated fiberglass mat and composite PP alternately to form a multi-layered composite structure. The layers are bonded to each other through MAH grafting and hydrogen bonding networks, resulting in strong interfacial bonding and significantly reduced interlayer delamination. The fiberglass layer provides load-bearing capacity and deformation constraint, while the polyurethane phase provides energy dissipation. The interfacial layer facilitates stress gradient transfer, and the flame-retardant component forms a composite carbon ceramic layer during combustion. The fiberglass network and metal oxide residues jointly support the carbon layer structure, enabling the shell to maintain structural integrity and functional stability under mechanical impact and high-temperature combustion conditions.

[0021] This invention pretreats glass fiber mat with a mixed solution of sulfuric acid and hydrogen peroxide, removing impurities from the fiber surface and increasing its surface roughness through etching. This provides more active sites for subsequent loading of metal oxides. The iron-zinc composite oxide loaded on the surface of the glass fiber mat not only has excellent thermal stability but also forms a stronger mechanical interlock with the PP matrix in the composite material. This allows the shell material to absorb and disperse energy more effectively when subjected to impact. Furthermore, the loaded metal oxide can catalyze carbonization and provide thermal insulation during battery shell combustion, effectively reducing ablation mass loss, increasing the oxygen index, and improving combustion performance. By using γ-aminopropyltriethoxysilane to finally activate the loaded glass fiber mat, the modified amino functional groups can chemically react with the maleic anhydride functional groups in the PP matrix, enhancing interfacial bonding, effectively preventing interlaminar cracking, and transferring impact stress from the weaker resin matrix to the high-strength glass fiber, thereby improving the impact toughness of the shell material.

[0022] This invention utilizes MAH-g-PP as a compatibilizer. The anhydride groups on its molecular chain can react with the amino functional groups on the surface of activated glass fiber mat, while its PP backbone is completely compatible with the PP matrix. This "in-situ compatibilization" significantly improves the interfacial adhesion between PP and glass fiber. Al-DOPO composite particles, through the nanoscale effect of nano-alumina and surface silanization modification, effectively improve their dispersibility and interfacial compatibility in the PP matrix. As rigid particles, the nano-alumina particles, when well-bonded with the matrix, can induce crazes and shear bands, absorbing and dispersing impact energy. Simultaneously, the potential interaction between the epoxy groups of γ-glycidyl etheroxypropyltrimethoxysilane and the PP matrix further reduces stress concentration and improves the material's impact toughness. DOPO is a highly efficient phosphorus-based flame retardant that, in the gas phase, captures... Free radicals are generated to exert flame retardant effects; melamine cyanurate can promote char formation and release inert gases when heated; nano-alumina may play a role in improving the quality and stability of the char layer, exerting flame retardant effects in both gas and solid phases, and improving the oxygen index and vertical combustion performance of the battery casing; by introducing siloxane segments into polyurethane, siloxane block polyurethane is prepared. During combustion, the siloxane segments tend to migrate to the material surface to form a high-temperature resistant silicon protective layer. This protective layer can effectively isolate heat and oxygen, further inhibiting combustion and producing excellent synergistic effects with the main flame retardant. In addition, siloxane block polyurethane has excellent flexibility and elasticity. Introducing it into composite PP can improve the toughness of composite PP. When the battery casing is subjected to external impact, siloxane block polyurethane can absorb and disperse energy, reducing the impact damage to the battery casing, thereby improving impact toughness. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In this invention, the specific gravity of the glass fiber mat is 20 g / m³. 2 The glass fiber length is 3-10mm, and it is selected from commercially available products from Zhengzhou Changyu New Material Technology Co., Ltd. In this invention, PP is general-purpose polypropylene, model number Sinopec Maoming PPH-Y40, selected from commercially available products of Dongguan Jinyuan Rongsheng New Materials Co., Ltd. In this invention, the effective component content of polytetrahydrofuran ether diol is 99%, the average molecular weight is 1000, and it is selected from commercially available products of Guangzhou Ruishi Biotechnology Co., Ltd. In this invention, the effective component content of the hydroxyl silicone oil is 99%, the average molecular weight is 500, the pH value is 6-9, and it is selected from commercially available materials from Hubei Longsheng Sihai New Materials Co., Ltd. In this invention, DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, with CAS number 35948-25-5; In this invention, the particle size of nano-alumina is 30-50 nm, and the content of effective components is 99.99%.

[0025] Example 1 This embodiment provides a method for preparing activated glass fiber mat, including the following steps: Step A1: Preparation of pretreated glass fiber mat 6 mol / L sulfuric acid and 20 wt% hydrogen peroxide were mixed evenly at a volume ratio of 6:1 to obtain a pretreatment solution; The glass fiber mat was completely immersed in the pretreatment solution, which was heated to 50°C and ultrasonically treated for 30 minutes. The glass fiber mat was then removed from the pretreatment solution, washed with purified water until neutral, and air-dried to obtain the pretreated glass fiber mat.

[0026] Sulfuric acid and hydrogen peroxide form a strong acid and strong oxidizing pretreatment solution. Sulfuric acid provides a strong acid environment to promote the hydrolysis of the silicon-oxygen network, while hydrogen peroxide provides an oxidant to generate active oxygen species, thereby achieving surface decontamination, etching, and hydroxylation. Ultrasound enhances the mass transfer process and accelerates the reaction rate, causing the glass fiber surface to transform from the original relatively inert Si-O-Si structure into an activated surface containing a large number of Si-OH groups, and forming a certain degree of micro-roughness, thus preparing a pretreated glass fiber mat.

[0027] Step A2: Preparation of the loaded glass fiber mat Ferric nitrate, zinc nitrate, urea, and purified water were added to a reaction flask at a ratio of 5g:4g:10g:60mL and stirred to dissolve, resulting in a mixed solution. Add the mixed solution to a vertical container, and then place the pretreated glass fiber mats stacked together into the vertical container at a solid-liquid ratio of 1g:5mL, ensuring that the pretreated glass fiber mats are completely submerged. Disperse the mixture ultrasonically for 30 minutes, then transfer the vertical container to a high-pressure reactor at 118℃ and maintain the temperature for 4 hours. After the reaction system is cooled to room temperature, remove the glass fiber mats from the solution, wash them three times with purified water, and then transfer them to a drying oven at 80℃ to dry to constant weight. Finally, transfer them to a muffle furnace at 350℃ and calcine them for 3 hours to obtain the supported glass fiber mats.

[0028] Glass fiber mat, as a carrier substrate, is pretreated to have a large number of Si-OH atoms and a rough microporous structure, forming surface support and loading sites. Urea decomposes under hydrothermal conditions, slowly releasing alkaline ions to control the precipitation rate of metal ions. Iron and zinc ions provided by ferric nitrate and zinc nitrate generate hydroxide or carbonate precursors in situ on the glass fiber surface. After calcination, they are converted into Fe-Zn composite oxides, thereby achieving uniform and firm loading of oxide particles on the glass fiber surface, thus preparing a loaded glass fiber mat.

[0029] Step A3: Preparation of activated glass fiber mat Anhydrous ethanol and 2 mol / L sodium hydroxide aqueous solution were mixed evenly at a volume ratio of 9:1 to obtain an ethanol solution; γ-aminopropyltriethoxysilane and ethanol solution were mixed evenly at a ratio of 1g:4mL to obtain an activated and modified solution; The activation and modification solution was applied at a rate of 2 mL / cm. 2 The appropriate amount of spraying agent is evenly sprayed onto the load-bearing glass fiber mat, and then transferred to a drying oven at 80°C to dry to constant weight, thus obtaining activated glass fiber mat.

[0030] The γ-aminopropyltriethoxysilane in the modification solution is hydrolyzed in an alkaline ethanol solution to generate amino-containing silanols. The silanol molecules partially condense to form oligomeric siloxanes, or undergo dehydration condensation with hydroxyl groups on the surface of glass fibers and their supported oxides to form covalent bonds. After drying, the silane molecules are further cross-linked and cured to form a stable silane coupling layer on the fiber surface, and the surface has -NH2 functional groups, thus preparing activated glass fiber mat.

[0031] Example 2 This embodiment provides a method for preparing activated glass fiber mat, including the following steps: Step A1: Preparation of pretreated glass fiber mat 7 mol / L sulfuric acid and 20 wt% hydrogen peroxide were mixed evenly at a volume ratio of 6:1 to obtain a pretreatment solution; The glass fiber mat was completely immersed in the pretreatment solution, which was heated to 55°C and ultrasonically treated for 40 minutes. The glass fiber mat was then removed from the pretreatment solution, washed with purified water until neutral, and air-dried to obtain the pretreated glass fiber mat.

[0032] Step A2: Preparation of the loaded glass fiber mat Ferric nitrate, zinc nitrate, urea, and purified water were added to a reaction flask at a ratio of 6g:5g:10g:60mL and stirred to dissolve, thus obtaining a mixed solution. The mixed solution was added to a vertical container, and then the pretreated glass fiber mats were stacked and placed into the vertical container at a solid-liquid ratio of 1g:5mL, so that the pretreated glass fiber mats were completely immersed. The mixture was ultrasonically dispersed for 40min. The vertical container was then transferred to a high-pressure reactor at 120℃ and kept at that temperature for 5h. The reaction system was then cooled to room temperature. The glass fiber mats were removed from the solution, washed three times with purified water, and then transferred to a drying oven at 85℃ to dry to constant weight. Finally, the mats were transferred to a muffle furnace at 360℃ and calcined for 3.5h to obtain the supported glass fiber mats.

[0033] Step A3: Preparation of activated glass fiber mat Anhydrous ethanol and 2.5 mol / L sodium hydroxide aqueous solution were mixed evenly at a volume ratio of 9:1 to obtain an ethanol solution. γ-aminopropyltriethoxysilane and ethanol solution were mixed evenly at a ratio of 1g:4.5mL to obtain the activated modified solution; The activation and modification solution was applied at a rate of 2.5 mL / cm². 2 The spraying amount is evenly sprayed onto the load-bearing glass fiber mat, and then transferred to a drying oven at 85°C to dry to constant weight, thus obtaining activated glass fiber mat.

[0034] Example 3 This embodiment provides a method for preparing activated glass fiber mat, including the following steps: Step A1: Preparation of pretreated glass fiber mat 8 mol / L sulfuric acid and 20 wt% hydrogen peroxide were mixed evenly at a volume ratio of 6:1 to obtain a pretreatment solution; The glass fiber mat was completely immersed in the pretreatment solution, which was heated to 60°C and ultrasonically treated for 50 minutes. The glass fiber mat was then removed from the pretreatment solution, washed with purified water until neutral, and air-dried to obtain the pretreated glass fiber mat.

[0035] Step A2: Preparation of the loaded glass fiber mat Ferric nitrate, zinc nitrate, urea, and purified water were added to a reaction flask at a ratio of 7g:6g:10g:60mL and stirred to dissolve, resulting in a mixed solution. Add the mixed solution to a vertical container, and then place the pretreated glass fiber mats stacked together into the vertical container at a solid-liquid ratio of 1g:5mL, ensuring that the pretreated glass fiber mats are completely submerged. Disperse the mixture ultrasonically for 50 minutes, then transfer the vertical container to a high-pressure reactor at 123℃ and maintain the temperature for 6 hours. After the reaction system is cooled to room temperature, remove the glass fiber mats from the solution, wash them three times with purified water, and then transfer them to a drying oven at 90℃ to dry to constant weight. Finally, transfer them to a muffle furnace at 370℃ and calcine them for 4 hours to obtain the supported glass fiber mats.

[0036] Step A3: Preparation of activated glass fiber mat Anhydrous ethanol and 3 mol / L sodium hydroxide aqueous solution were mixed evenly at a volume ratio of 9:1 to obtain an ethanol solution; γ-aminopropyltriethoxysilane and ethanol solution were mixed evenly at a ratio of 1g:5mL to obtain an activated and modified solution; The activation and modification solution was applied at a rate of 3 mL / cm. 2 The spraying amount is evenly sprayed onto the load-bearing glass fiber mat, and then transferred to a drying oven at 70°C to dry to constant weight, thus obtaining activated glass fiber mat.

[0037] Example 4 This embodiment provides a method for preparing composite PP, including the following steps: Step B1: Preparation of MAH-g-PP Weigh out 1000g of PP, 10g of styrene, and 28g of maleic anhydride and add them to a torque rheometer at 180℃. Set the torque rheometer speed to 60r / min and mix for 3min. Add 0.3g of initiator dicumyl peroxide to the torque rheometer and mix for 8min. Cool the torque rheometer to room temperature, discharge the material, and granulate to obtain MAH-g-PP.

[0038] In the reaction process, PP is used as the main chain polymer, maleic anhydride is used as the polar monomer, and styrene is used as the copolymerization aid to improve the dispersion and reactivity of maleic anhydride in PP. Dicumyl peroxide is used as a free radical initiator. Under the initiation of dicumyl peroxide, the PP molecular chain generates free radicals. Styrene is used as a comonomer to improve the grafting efficiency of maleic anhydride. The three react under high temperature melt mixing conditions to introduce polar groups on the PP chain segment and prepare MAH-g-PP.

[0039] Step B2: Preparation of siloxane block polyurethane Weigh out 290g of polytetrahydrofuran ether diol, 480g of hydroxyl silicone oil, 1g of dibutyltin dilaurate catalyst, and 2000mL of toluene and add them to an argon-protected reaction flask. Stir the mixture and raise the temperature of the reaction flask to 60℃. Calculate the amount of isophorone diisocyanate to be added based on 0.55 times the total molar amount of hydroxyl groups in the mixture of polytetrahydrofuran ether diol and hydroxyl silicone oil, and add it to the reaction flask. Keep the reaction temperature high for 40 min. Add 50g of 2-(aminomethyl)propane-1,3-diamine to the reaction flask and keep the reaction temperature high for 30 min. Add 200g of glycidyl ether to the reaction flask and keep the reaction temperature high for 50 min. Raise the temperature of the reaction flask to 80℃, apply a negative pressure to -0.1MPa, remove low-boiling-point substances by vacuum distillation, discharge the material while hot, cool and solidify, and granulate to obtain siloxane block polyurethane.

[0040] The reaction is catalyzed by dibutyltin dilaurate, in which the isocyanate groups of isophorone diisocyanate react with the hydroxyl groups on the molecular chains of polyether glycol or hydroxyl silicone oil to generate an isocyanate-terminated prepolymer. 2-(aminomethyl)propane-1,3-diamine is used as a chain extender to enhance the crosslinking between the prepolymer segments. Finally, glycidyl is used for end-capping to obtain a polymer material containing a triple block structure of polyether, polysiloxane and polyurethane.

[0041] Step B3: Preparation of flame retardant A 10wt% sodium silicate aqueous solution and γ-glycidoxypropyltrimethoxysilane were mixed evenly at a weight ratio of 30:0.6 to obtain a silicate mixture. Weigh out 20g of DOPO, 50g of nano-alumina, 200mL of anhydrous ethanol and 6g of sodium dodecyl sulfate and add them to a reaction flask. Mix them and raise the temperature of the reaction flask to 50℃. Disperse the mixture by sonication for 30min. Cool the reaction flask to 23℃ and fix it on an iron stand with a mechanical stirrer. Add 3000mL of purified water to the reaction flask and stir for 60min. Add glacial acetic acid to the reaction flask to adjust the pH of the system to 3. Add 300g of silica mixture to the reaction flask and raise the temperature of the reaction flask to 78℃. Keep the temperature and stir for 3h. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with purified water and anhydrous ethanol and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain Al-DOPO composite particles. During the reaction, DOPO is dissolved in anhydrous ethanol and then mixed with nano-alumina by ultrasound. Purified water is then added to dilute the mixture, making the DOPO molecules more evenly distributed on the surface of the nano-alumina particles. Sodium silicate further condenses under acidic conditions to form a silica sol with a Si-O-Si network structure. γ-glycidoxypropyltrimethoxysilane undergoes a condensation reaction with the silica sol formed by the hydrolysis of sodium silicate under acidic conditions, forming an organic-inorganic co-condensed silicon-oxygen network structure on the outside of the particles.

[0042] Al-DOPO composite particles and melamine cyanurate were mixed at a weight ratio of 3:1 to obtain a flame retardant.

[0043] Step B4: Preparation of composite PP Diisopropyl phthalate, calcium stearate, ethylene dioleamide and antioxidant 1010 were mixed in a weight ratio of 5:2:1:1 to obtain an auxiliary additive. Weigh out the following components by weight: 60 parts PP, 30 parts MAH-g-PP, 20 parts siloxane block polyurethane, 15 parts flame retardant, and 3 parts auxiliary additives. Mix them and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 170℃, 170℃, 170℃, and 180℃ respectively. Set the spindle speed to 15 r / min. After melting and mixing for 2 minutes, extrude the mixture through the die to obtain a composite PP with a thickness of 1.8 mm.

[0044] Example 5 This embodiment provides a method for preparing composite PP, including the following steps: Step B1: Preparation of MAH-g-PP Weigh out 1000g of PP, 10g of styrene, and 30g of maleic anhydride and add them to a torque rheometer at 185℃. Set the torque rheometer speed to 65r / min and mix for 4min. Add 0.3g of initiator dicumyl peroxide to the torque rheometer and mix for 10min. Cool the torque rheometer to room temperature, discharge the material, and granulate to obtain MAH-g-PP.

[0045] Step B2: Preparation of siloxane block polyurethane Weigh out 300g of polytetrahydrofuran ether diol, 500g of hydroxyl silicone oil, 1g of dibutyltin dilaurate catalyst, and 2000mL of toluene and add them to an argon-protected reaction flask. Stir the mixture and raise the temperature of the reaction flask to 65℃. Calculate the amount of isophorone diisocyanate to be added based on 0.55 times the total molar amount of hydroxyl groups in the mixture of polytetrahydrofuran ether diol and hydroxyl silicone oil, and add it to the reaction flask. Keep the reaction temperature high for 45 min. Add 50g of 2-(aminomethyl)propane-1,3-diamine to the reaction flask and keep the reaction temperature high for 40 min. Add 200g of glycidyl ether to the reaction flask and keep the reaction temperature high for 55 min. Raise the temperature of the reaction flask to 80℃, apply a negative pressure to -0.1MPa, remove low-boiling-point substances by vacuum distillation, discharge the material while hot, cool and solidify, and granulate to obtain siloxane block polyurethane.

[0046] Step B3: Preparation of flame retardant A 10wt% sodium silicate aqueous solution and γ-glycidoxypropyltrimethoxysilane were mixed evenly at a weight ratio of 30:0.7 to obtain a silicate mixture. Weigh out 25g of DOPO, 50g of nano-alumina, 200mL of anhydrous ethanol and 7g of sodium dodecyl sulfate and add them to a reaction flask. Mix them and raise the temperature of the reaction flask to 55℃. Disperse the mixture by sonication for 40min. Cool the reaction flask to 26℃ and fix it on an iron stand with a mechanical stirrer. Add 3000mL of purified water to the reaction flask and stir for 70min. Add glacial acetic acid to the reaction flask to adjust the pH of the system to 3.5. Add 300g of silica mixture to the reaction flask and raise the temperature of the reaction flask to 80℃. Keep the temperature and stir for 4h. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with purified water and anhydrous ethanol and then dry it. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain Al-DOPO composite particles. Al-DOPO composite particles and melamine cyanurate were mixed at a weight ratio of 3:1 to obtain a flame retardant.

[0047] Step B4: Preparation of composite PP Diisobutyl phthalate, zinc stearate, ethylene bisoleamide and antioxidant 1076 were mixed in a weight ratio of 5:2:1:1 to obtain an auxiliary additive. Weigh out the following components by weight: 64 parts PP, 33 parts MAH-g-PP, 23 parts siloxane block polyurethane, 16.5 parts flame retardant, and 5 parts auxiliary additives. Mix them and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 170℃, 170℃, 170℃, and 180℃ respectively. Set the spindle speed to 17 r / min. After melting and mixing for 2.5 min, extrude the mixture through the die to obtain a composite PP with a thickness of 1.9 mm.

[0048] Example 6 This embodiment provides a method for preparing composite PP, including the following steps: Step B1: Preparation of MAH-g-PP Weigh out 1000g of PP, 10g of styrene, and 32g of maleic anhydride and add them to a torque rheometer at 190℃. Set the torque rheometer speed to 70r / min and mix for 5min. Add 0.3g of initiator dicumyl peroxide to the torque rheometer and mix for 12min. Cool the torque rheometer to room temperature, discharge the material, and granulate to obtain MAH-g-PP.

[0049] Step B2: Preparation of siloxane block polyurethane Weigh out 310g of polytetrahydrofuran ether diol, 520g of hydroxyl silicone oil, 1g of dibutyltin dilaurate catalyst, and 2000mL of toluene and add them to an argon-protected reaction flask. Stir the mixture and raise the temperature of the reaction flask to 70℃. Calculate the amount of isophorone diisocyanate to be added based on 0.55 times the total molar amount of hydroxyl groups in the mixture of polytetrahydrofuran ether diol and hydroxyl silicone oil, and add it to the reaction flask. Keep the reaction temperature high for 50 min. Add 50g of 2-(aminomethyl)propane-1,3-diamine to the reaction flask and keep the reaction temperature high for 50 min. Add 200g of glycidyl ether to the reaction flask and keep the reaction temperature high for 60 min. Raise the temperature of the reaction flask to 80℃, apply a negative pressure to -0.1MPa, remove low-boiling-point substances by vacuum distillation, discharge the material while hot, cool and solidify, and granulate to obtain siloxane block polyurethane.

[0050] Step B3: Preparation of flame retardant A 10wt% sodium silicate aqueous solution and γ-glycidoxypropyltrimethoxysilane were mixed evenly at a weight ratio of 30:0.8 to obtain a silicate mixture. Weigh out 30g of DOPO, 50g of nano-alumina, 200mL of anhydrous ethanol and 8g of sodium dodecyl sulfate and add them to a reaction flask. Mix them and raise the temperature of the reaction flask to 60℃. Disperse the mixture by sonication for 50min. Cool the reaction flask to 28℃ and fix it on an iron stand with a mechanical stirrer. Add 3000mL of purified water to the reaction flask and stir for 80min. Add glacial acetic acid to the reaction flask to adjust the pH of the system to 4. Add 300g of silica mixture to the reaction flask and raise the temperature of the reaction flask to 82℃. Keep the temperature and stir for 5h. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with purified water and anhydrous ethanol and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain Al-DOPO composite particles. Al-DOPO composite particles and melamine cyanurate were mixed at a weight ratio of 3:1 to obtain a flame retardant.

[0051] Step B4: Preparation of composite PP Dioctyl phthalate, barium stearate, ethylene bisoleamide and antioxidant 1010 were mixed in a weight ratio of 5:2:1:1 to obtain an auxiliary additive. Weigh out the following components by weight: 68 parts PP, 35 parts MAH-g-PP, 26 parts siloxane block polyurethane, 19 parts flame retardant, and 5 parts auxiliary additives. Mix them and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 170℃, 170℃, 170℃, and 180℃ respectively. Set the spindle speed to 18r / min. After melting and mixing for 3 minutes, extrude the mixture through the die to obtain a composite PP with a thickness of 2mm.

[0052] Example 7 This embodiment provides a method for preparing a PP-glass fiber composite battery casing for new energy vehicles, specifically as follows: Using activated glass fiber mat prepared in two Examples 1 and composite PP prepared in three Examples 4 as raw materials, the activated glass fiber mat and composite PP were alternately layered and then added to a hot press at a temperature of 180°C and a pressure of 7MPa. After hot pressing for 4 minutes, the mixture was naturally cooled to room temperature to obtain a PP-glass fiber composite new energy vehicle battery shell.

[0053] Example 8 This embodiment provides a method for preparing a PP-glass fiber composite battery casing for new energy vehicles, specifically as follows: Using activated glass fiber mats prepared in two Examples 2 and composite PP prepared in three Examples 5 as raw materials, the activated glass fiber mats and composite PP were alternately layered and then added to a hot press at a temperature of 185°C and a pressure of 6MPa. After hot pressing for 5.5 minutes, the mixture was allowed to cool naturally to room temperature to obtain a PP-glass fiber composite new energy vehicle battery shell.

[0054] Example 9 This embodiment provides a method for preparing a PP-glass fiber composite battery casing for new energy vehicles, specifically as follows: Using activated glass fiber mat prepared in two Examples 3 and composite PP prepared in three Examples 6 as raw materials, the activated glass fiber mat and composite PP were alternately layered and then added to a hot press at a temperature of 190°C and a pressure of 5MPa. After hot pressing for 7 minutes, the mixture was naturally cooled to room temperature to obtain a PP-glass fiber composite new energy vehicle battery shell.

[0055] Comparative Example 1 The difference between this comparative example and Example 9 is that, in the preparation of the activated glass fiber mat, step A2 is omitted, and the pretreated glass fiber mat prepared in step A1 is used instead of the loaded glass fiber mat in step A3 to prepare the activated glass fiber mat.

[0056] Comparative Example 2 The difference between this comparative example and Example 9 is that, in the preparation of the composite PP, step B1 was omitted and MAH-g-PP was not added in step B4.

[0057] Comparative Example 3 The difference between this comparative example and Example 9 is that, in the preparation of the composite PP, step B2 was omitted, and siloxane-block polyurethane was not added in step B4.

[0058] Comparative Example 4 The difference between this comparative example and Example 9 is that no silica mixture was added to the composite PP used in step B3 when preparing Al-DOPO composite particles.

[0059] Performance testing: The impact toughness of the PP-glass fiber composite new energy vehicle battery shell samples prepared in Examples 7-9 and Comparative Examples 1-4 was determined in accordance with the standard GB / T 1451-2005 "Test Method for Impact Toughness of Fiber Reinforced Plastics in Simply Supported Beams". The ablation mass loss of the PP-glass fiber composite new energy vehicle battery shell samples prepared in Examples 7-9 and Comparative Examples 1-4 was determined according to the standard GB / T 6011-2005 "Test Method for Combustion Performance of Fiber Reinforced Plastics - Incandescent Rod Method". The oxygen index of the PP-glass fiber composite new energy vehicle battery shell samples prepared in Examples 7-9 and Comparative Examples 1-4 was determined according to the standard GB / T 8924-2005 "Test Method for Combustion Performance of Fiber Reinforced Plastics - Oxygen Index Method". The flammability ratings of the PP-glass fiber composite new energy vehicle battery shell samples prepared in Examples 7-9 and Comparative Examples 1-4 were determined by vertical burning tests according to the standard GB / T 22472-2008 "Determination of flammability of plastics for instrument and equipment components". The specific test data are shown in Table 1 below.

[0060] Table 1 - Performance Test Data of Samples Data Analysis: Comparative analysis of the data in Table 1 above shows that the impact toughness of the PP-glass fiber composite new energy vehicle battery shell sample prepared by this invention reaches 45.9 kJ / m. 2 The corrosion mass loss was reduced to 0.81%, the oxygen index reached 33.8%, and the combustion performance level reached V-0. All performance test data were better than the comparative example, indicating that the present invention significantly improved the impact toughness, high temperature stability and flame retardant performance of PP-glass fiber composite material through the organic combination of interface activation, block copolymerization and multi-element synergistic flame retardant technology, which significantly improved the safety and structural performance of the battery shell of new energy vehicles.

[0061] 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 specific implementations. 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 PP-glass composite new energy vehicle battery shell, characterized in that, The PP-glass fiber composite new energy vehicle battery shell is formed by alternately stacking and hot pressing a plurality of activated glass fiber mats and composite PP. The preparation method of the activated glass fiber mat comprises the following steps: using an activation modification liquid containing gamma-aminopropyl triethoxysilane to perform surface modification on a supported glass fiber mat loaded with iron and zinc oxides, and obtaining the activated glass fiber mat. The composite PP comprises the following components in parts by weight: 60-68 parts of PP, 30-35 parts of MAH-g-PP, 20-26 parts of siloxane block polyurethane, 15-19 parts of a flame retardant, and 3-5 parts of auxiliary additives, wherein the flame retardant is obtained by mixing Al-DOPO composite particles and melamine cyanurate at a weight ratio of 3:

1.

2. The PP-glass composite new energy vehicle battery shell according to claim 1, characterized in that, The activated glass fiber mat is obtained by the following steps: A1, immerse the glass fiber mat in a pretreatment solution, heat the pretreatment solution to 50-60 DEG C, ultrasonic treatment for 30-50 min, take out the glass fiber mat from the pretreatment solution, wash it to neutral with purified water, and dry naturally to obtain a pretreated glass fiber mat; A2, immerse the pretreated glass fiber mat in a mixed solution, keep it fully immersed, ultrasonic dispersion for 30-50 min, transfer the reaction system to a high-pressure reaction kettle with a temperature of 118-123 DEG C, heat treatment for 4-6 h, post-treatment, and obtain a supported glass fiber mat; A3, uniformly spray the activation modification liquid on the supported glass fiber mat, post-treatment, and obtain the activated glass fiber mat.

3. The PP-glass fiber composite new energy vehicle battery shell according to claim 2, characterized in that, In step A1, the pretreatment solution is obtained by mixing 6-8 mol / L sulfuric acid and 20 wt% hydrogen peroxide at a volume ratio of 6:1; in step A2, the mixed solution is obtained by mixing and stirring iron nitrate, zinc nitrate, urea and purified water at a use amount ratio of 5-7 g:4-6 g:10 g:60 mL, and the use amount ratio of the pretreated glass fiber felt and the mixed solution is 1 g:5 mL; in step A3, the spraying amount of the activation modification liquid is 2-3 mL / cm 2 , and the activation modification liquid is composed of γ-aminopropyl triethoxysilane and an ethanol solution at a use amount ratio of 1 g:4-5 mL, wherein the ethanol solution is composed of anhydrous ethanol and a 2-3 mol / L sodium hydroxide aqueous solution at a volume ratio of 9:

1.

4. The PP-glass composite new energy vehicle battery shell according to claim 1, characterized in that, The preparation method of the Al-DOPO composite particles comprises the following steps: mixing DOPO, nano-alumina, anhydrous ethanol and sodium dodecyl sulfate, increasing the temperature of the reaction system to 50-60 DEG C, ultrasonic dispersion for 30-50 min, reducing the temperature of the reaction system to 23-28 DEG C, adding purified water to the reaction system, stirring for 60-80 min, adding acetic acid to the reaction system to adjust the pH value to 3-4, adding a silicic acid mixture to the reaction system, increasing the temperature of the reaction system to 78-82 DEG C, heat preservation and stirring for 3-5 h, post-treatment, and obtaining the Al-DOPO composite particles.

5. The PP-glass fiber composite new energy vehicle battery shell according to claim 4, characterized in that, The amount ratio of the DOPO, nano-alumina, anhydrous ethanol, sodium dodecyl sulfate, purified water and silicic acid mixture is 2-3 g:5 g:20 mL:0.6-0.8 g:300 mL:30 g, and the silicic acid mixture is composed of 10wt% sodium silicate aqueous solution and gamma-glycidyl ether oxypropyl trimethoxysilane at a weight ratio of 30:0.6-0.

8.

6. The PP-glass composite new energy vehicle battery shell according to claim 1, characterized in that, The preparation method of the siloxane block polyurethane comprises the following steps: mixing polytetrahydrofuran ether diol, hydroxyl silicone oil, a catalyst and toluene under inert gas protection, increasing the temperature of the reaction system to 60-70 DEG C, adding isophorone diisocyanate to the reaction system, heat preservation and reaction for 40-50 min, adding a chain extender to the reaction system, heat preservation and reaction for 30-50 min, adding a capping agent to the reaction system, heat preservation and reaction for 50-60 min, post-treatment, and obtaining the siloxane block polyurethane.

7. The PP-glass fiber composite new energy vehicle battery shell according to claim 6, characterized in that, The use amount ratio of the polytetrahydrofuran ether glycol, the hydroxyl silicone oil, the catalyst, the toluene, the chain extender and the end-capping agent is 2.9-3.1 g:4.8-5.2 g:0.01 g:20 mL:0.5 g:2 g, the catalyst is dibutyltin dilaurate, the molar amount of the isophorone diisocyanate is 0.55 times of the total molar amount of hydroxyl groups in the mixture composed of the polytetrahydrofuran ether glycol and the hydroxyl silicone oil, the chain extender is 2-(aminomethyl)propane-1,3-diamine, and the end-capping agent is glycidol.

8. The PP-glass composite new energy vehicle battery shell according to claim 1, characterized in that, The preparation method of the MAH-g-PP is as follows: the PP, the styrene and the maleic anhydride are added into a torque rheometer with a temperature of 180-190 DEG C, and mixed for 3-5 min; the initiator is added into the torque rheometer, and mixed for 8-12 min; the torque rheometer is cooled to room temperature; and after discharging, the pelletization is carried out to obtain the MAH-g-PP.

9. The PP-glass fiber composite new energy vehicle battery shell according to claim 8, characterized in that, The weight ratio of the PP, the styrene, the maleic anhydride and the initiator is 100:1:2.8-3.2:0.03, the rotation speed of the torque rheometer is 60-70 r / min, and the initiator is dicumyl peroxide.

10. A method for preparing the PP-glass composite new energy vehicle battery shell according to any one of claims 1-9, characterized in that, The method comprises the following steps: S1, the PP, the MAH-g-PP, the silicone block polyurethane, the flame retardant and the auxiliary additive are mixed, and then added into a twin-screw extruder for melt mixing for 2-3 min, and then extruded through a die to obtain a composite PP; S2, three composite PPs and two activated glass fiber mats are alternately stacked, and then added into a hot press with a temperature of 180-190 DEG C and a pressure of 5-7 MPa, and hot-pressed for 4-7 min after heat preservation and pressure retention, and then naturally cooled to room temperature to obtain a PP-glass fiber composite new energy automobile battery shell.

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