A halogen-free flame-retardant unsaturated polyester resin material special for energy storage battery shell and a preparation method thereof

Abstract

This invention relates to the field of polymer materials technology, specifically disclosing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings and its preparation method. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 35-45 parts unsaturated dicarboxylic acid, 15-30 parts polymeric polyol, 15-25 parts small molecule diol, 35-45 parts styrene, 15-25 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 8-15 parts organic phosphinate, 0.5-2 parts organometallic catalyst, 0.01-1 part polymerization inhibitor, and 1.2-2.0 parts curing agent. The phosphorus-nitrogen-silicon modified aluminum hydroxide and organic phosphinate are compounded to construct a synergistic halogen-free flame-retardant system. The two work synergistically to improve the flame-retardant effect under halogen-free conditions, while simultaneously suppressing smoke, meeting the fire safety requirements of energy storage battery casings.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings and its preparation method. Background Technology

[0002] With the rapid development of the new energy storage industry, energy storage battery modules are continuously upgrading towards higher capacity, higher integration, and higher power density, and the requirements for thermal safety protection and structural stability of battery systems are becoming increasingly stringent. As the core load-bearing and protective structure of energy storage batteries, the battery casing needs to simultaneously meet comprehensive performance requirements such as high strength, high toughness, high heat resistance, low smoke, halogen-free flame retardancy, and excellent dimensional stability. It is a key structural component to ensure the safe operation of energy storage batteries.

[0003] Unsaturated polyester resins possess advantages such as good moldability, moderate cost, high structural strength, and resistance to chemical corrosion, making them widely used in composite material structural components and a preferred matrix material for lightweight battery casings as a replacement for metal materials. However, conventional unsaturated polyester resins themselves have poor flame retardant properties, low limiting oxygen index, and produce dripping and excessive smoke during combustion, failing to meet the stringent fire safety standards for energy storage batteries. Therefore, halogen-free flame retardant modification is necessary to achieve safety upgrades.

[0004] Existing halogen-free flame-retardant unsaturated polyester systems mostly employ physical blending modification with aluminum hydroxide and organic phosphonates, which has several drawbacks: First, the unmodified aluminum hydroxide has weak interfacial bonding with the resin, resulting in significant deterioration of the material's mechanical properties and low-temperature toughness under high filler conditions, making it prone to cracking under alternating hot and cold temperatures; Second, the flame-retardant components are simply blended, leading to severe powder agglomeration, making it difficult to generate a continuous and dense char layer during combustion, resulting in poor synergistic effect of flame retardancy and smoke suppression; Third, the polyester synthesis uses only a single diol, resulting in an imbalance of molecular chain rigidity and flexibility, and insufficient dimensional stability over a wide temperature range; Fourth, most commercially available modified aluminum hydroxide is a single-step silane-amino modification, lacking a phosphorus-nitrogen-silicon covalent integrated structure in the powder, relying solely on a single condensed phase flame-retardant mechanism, making it difficult to simultaneously achieve a balance between high flame retardancy, low smoke, and excellent mechanical properties.

[0005] Based on the above statements, the present invention provides a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings and its preparation method. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings and its preparation method.

[0007] In a first aspect, the present invention provides a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings. This material is first synthesized from unsaturated diacids, polymeric polyols, and small molecule diols through a polycondensation reaction under the action of an organometallic catalyst to form an unsaturated polyester matrix resin, which is then compounded with phosphorus-nitrogen-silicon modified aluminum hydroxide and organic phosphines. The specific technical solution is as follows: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 35-45 parts of unsaturated dicarboxylic acid, 15-30 parts of polymeric polyol, 15-25 parts of small molecule diol, 35-45 parts of styrene, 15-25 parts of phosphorus-nitrogen-silicon modified aluminum hydroxide, 8-15 parts of organic phosphonate, 0.5-2 parts of organometallic catalyst, 0.01-1 part of polymerization inhibitor, and 1.2-2.0 parts of curing agent.

[0008] Preferably, the unsaturated dicarboxylic acid includes at least one of maleic acid, fumaric acid, itaconic acid, pentenoic acid, hexenedioic acid, and 4,4'-stilbenedicarboxylic acid.

[0009] Preferably, the polymeric polyol includes at least one of polycaprolactone diol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether diol, and polycarbonate diol.

[0010] Preferably, the small molecule diol includes at least two of ethylene glycol, 1,3-propanediol, 1,5-pentanediol, neopentanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, and 1,3-cyclohexanediol.

[0011] Preferably, the molar ratio of the total hydroxyl groups provided by the polymer polyol and the small molecule diol to the total carboxyl groups provided by the unsaturated diacid is 1.05 to 1.15:1.

[0012] Preferably, the phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Disperse aluminum hydroxide in an ethanol-water mixed solvent to form a suspension with a solid content of 20-25 wt%. Adjust the pH of the system to 7.5-9.0, add N-[3-(trimethoxysilyl)propyl]ethylenediamine, and react at 60-70℃ for 2-4 h. The reaction product is filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Ammoniated modified aluminum hydroxide is dispersed in anhydrous tetrahydrofuran to form a suspension with a solid content of 20-30 wt%. Diphenylphosphonic chloride and triethylamine are added, and the mixture is stirred at 25-40℃ for 6-12 h. The reaction product is filtered, washed, dried, and sieved to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0013] Preferably, the mass of N-[3-(trimethoxysilyl)propyl]ethylenediamine is 4-8% of the mass of aluminum hydroxide; the mass of diphenylphosphonic chloride is 5-10% of the mass of aminated aluminum hydroxide; and the mass of triethylamine is 3-6% of the mass of aminated aluminum hydroxide. Preferably, the volume ratio of the ethanol-water mixed solvent is 8 to 10:1.

[0014] Preferably, the organic phosphonate includes at least one of zinc dimethylphosphonate, zinc diethylphosphonate, aluminum diethylphosphonate, aluminum dimethylphosphonate, and aluminum phenylmethylphosphonate.

[0015] Preferably, the organometallic catalyst includes at least one of dibutyltin oxide, antimony glycolate, and zinc acetate.

[0016] Preferably, the polymerization inhibitor includes at least one of phenothiazine, catechol, and tert-butylcatechol.

[0017] Secondly, this invention provides a method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings, employing the following technical solution: A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, an inert gas is introduced to carry out a normal pressure prepolymerization reaction. When the acid value of the system drops to 60-80 mg KOH / g, the normal pressure prepolymerization reaction is completed. Then, a gradient decompression polymerization reaction is carried out until the acid value of the system drops to 20-40 mg KOH / g. The reaction is stopped, the temperature is lowered to 90-110℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and an unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place it in the mold, and cure it under molding pressure of 10-15MPa at 110-130℃ for 3 hours. After cooling and demolding, a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell is obtained.

[0018] Preferably, the heating program for the atmospheric pressure prepolymerization reaction in step (1) is as follows: the temperature is raised to 160-170°C within 1.5 hours, and the temperature is continued to rise in a gradient, raising the temperature to 180-190°C within a total of 4 hours.

[0019] Preferably, the pressure reduction polymerization in step (1) adopts a gradient pressure reduction process: after the atmospheric pressure prepolymerization reaction is completed, the system pressure is reduced to 30-50 kPa within 1 hour, the reaction temperature is maintained at 190-200℃, and the reaction is kept at the temperature for 1-2 hours; then the pressure is further reduced to 5-15 kPa, and the temperature is simultaneously raised to 205-215℃ for deep pressure reduction polymerization.

[0020] In summary, the present invention has the following beneficial effects: 1. This invention uses a two-step chemical grafting process to obtain phosphorus, nitrogen, and silicon modified aluminum hydroxide. The flame-retardant elements phosphorus, nitrogen, and silicon are covalently bonded to the surface of aluminum hydroxide particles, which not only improves the interfacial compatibility between inorganic fillers and unsaturated polyester matrix and reduces filler agglomeration, but also achieves multi-element synergistic flame retardancy, reduces the amount of filler required for pure aluminum hydroxide flame retardancy, and alleviates the problem of significant decline in material mechanical properties caused by high filler content.

[0021] 2. This invention combines phosphorus-nitrogen-silicon modified aluminum hydroxide with organic phosphonates to construct a synergistic halogen-free flame retardant system. The two work synergistically to improve the flame retardant effect under halogen-free conditions, while suppressing smoke, thus meeting the fire safety requirements of energy storage battery casings.

[0022] 3. This invention uses a blend of polymeric polyols and small-molecule diols as alcohol components to regulate the structure of the unsaturated polyester backbone, thereby improving the material's toughness, enhancing the shell's impact resistance, and reducing the risk of cracking while retaining the resin's heat resistance.

[0023] 4. This invention employs a melt polycondensation process involving atmospheric pressure prepolymerization reaction and gradient decompression polymerization reaction, and sets two acid value control points, which can stabilize the structure and molecular weight of the matrix resin, resulting in good batch stability. The matrix resin has good compatibility with inorganic flame-retardant fillers, making it suitable for preparing composite materials for energy storage battery casings. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments.

[0025] Unless otherwise specified, all materials and reagents used in this invention are commercially available. Specifically, polycaprolactone glycol (CAS No. 36890-68-3, average molecular weight 530) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; polyethylene glycol (CAS No. 25322-68-3, average molecular weight 400) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; polypropylene glycol (CAS No. 25322-69-4, average molecular weight 400) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; polycarbonate glycol (CAS No. 29862-10-0, average molecular weight 2000) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; and aluminum hydroxide (Catalog No. A637229, ≥99.5%, -800 mesh) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] Examples 1-3 provide a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings and its preparation method.

[0027] Example 1:

[0028] A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 36 parts unsaturated dicarboxylic acid, 25 parts polymeric polyol, 20 parts small molecule diol, 40 parts styrene, 20 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 10 parts organic phosphonate, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent; The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymeric polyol is polycaprolactone diol; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organic phosphonate is zinc dimethylphosphonate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0029] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 8:1 to prepare a suspension with a solid content of 20wt%. Ammonia solution with a mass fraction of 5% was added dropwise to adjust the pH of the system to 7.5. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 4% of aluminum hydroxide was added, and the reaction was carried out at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 20 wt%. Add 5% by mass of diphenylphosphonic chloride and 3% by mass of triethylamine to the aminated modified aluminum hydroxide. Stir and react at 30°C for 8 hours. After the reaction is completed, filter, wash, dry and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0030] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 10MPa at 110℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0031] Example 2:

[0032] A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 40 parts unsaturated dicarboxylic acid, 20 parts polymeric polyol, 21 parts small molecule diol, 35 parts styrene, 15 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 8 parts organic phosphonates, 1.5 parts organometallic catalyst, 0.5 parts polymerization inhibitor, and 1.5 parts curing agent.

[0033] The unsaturated dicarboxylic acid is obtained by mixing fumaric acid, itaconic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 1:3:1; the polymer polyol is polyethylene glycol; the small molecule diol is obtained by mixing ethylene glycol and 2-methyl-1,3-propanediol in a mass ratio of 1:2; the organic phosphite is phenylmethyl aluminum hypophosphite; the organometallic catalyst is antimony glycolate; the polymerization inhibitor is catechol; and the curing agent is tert-butylperbenzoic acid.

[0034] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 9:1 to prepare a suspension with a solid content of 23wt%. Ammonia solution with a mass fraction of 8% was added dropwise to adjust the pH of the system to 8.0. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 6% of aluminum hydroxide was added, and the reaction was carried out at 65℃ for 3 hours. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 25 wt%. Add 7.5% by mass of diphenylphosphonic chloride and 4.5% by mass of triethylamine, and stir the mixture at 25°C for 12 h. After the reaction is completed, filter, wash, dry, and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0035] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 165℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 185℃ within 4h. When the acid value of the system drops to 70mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 40kPa within 1h, and the reaction is kept at the temperature for 1.5h. The pressure is further reduced to 10kPa, and the temperature is raised to 210℃ for deep pressure reduction polymerization until the acid value of the system drops to 30mg KOH / g. The reaction is stopped, the temperature is lowered to 100℃, the remaining polymerization inhibitor is added and styrene is stirred and diluted to obtain the unsaturated polyester resin matrix. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 12MPa at 120℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0036] Example 3:

[0037] A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 40 parts unsaturated dicarboxylic acid, 20 parts polymeric polyol, 20 parts small molecule diol, 45 parts styrene, 25 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 15 parts organic phosphonate, 2 parts organometallic catalyst, 1 part polymerization inhibitor, and 2.0 parts curing agent.

[0038] The unsaturated dicarboxylic acid is obtained by mixing fumaric acid, pentenic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 1:2:1; the polymeric polyol is obtained by mixing polypropylene glycol and polycarbonate diol in a mass ratio of 4:1; the small molecule diol is obtained by mixing ethylene glycol and neopentyl glycol in a mass ratio of 1:1; the organic phosphonate is aluminum diethylphosphonate; the organometallic catalyst is zinc acetate; the polymerization inhibitor is tert-butylcatechol; and the curing agent is tert-butylperbenzoic acid.

[0039] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 10:1 to prepare a suspension with a solid content of 25 wt%. Ammonia solution with a mass fraction of 10% was added dropwise to adjust the pH of the system to 9.0. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 8% of aluminum hydroxide was added, and the reaction was carried out at 70℃ for 4 h. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 30 wt%. Add 10% by mass of diphenylphosphonic chloride and 6% by mass of triethylamine to the aminated modified aluminum hydroxide. Stir and react at 40°C for 6 h. After the reaction is completed, filter, wash, dry and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0040] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 160℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 180℃ within 4h. When the acid value of the system drops to 80mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 50kPa within 1h, the reaction temperature is maintained at 200℃, and the reaction is kept at this temperature for 2h. The pressure is further reduced to 15kPa, and the temperature is raised to 215℃ to carry out deep pressure reduction polymerization until the acid value of the system drops to 40mg KOH / g. The reaction is stopped, the temperature is lowered to 110℃, the remaining polymerization inhibitor is added and styrene is stirred and diluted to obtain the unsaturated polyester resin matrix. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure at 120℃ for 3 hours under molding pressure of 15MPa. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0041] To verify the performance of the halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings obtained in Examples 1-3 of this invention, comparative examples 1-6 were set up.

[0042] Comparative Example 1 Comparative Example 1 differs from Example 1 in that, while maintaining the molar ratio of total hydroxyl groups to total carboxyl groups and the total mass of the matrix resin monomers, only the polymer polyol is used as the alcohol component, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 16 parts unsaturated dicarboxylic acid, 65 parts polymeric polyol, 40 parts styrene, 20 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 10 parts organic phosphonate, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent.

[0043] The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymer polyol is polycaprolactone diol; the organic phosphonate is zinc dimethyl phosphonate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0044] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 8:1 to prepare a suspension with a solid content of 20wt%. Ammonia solution with a mass fraction of 5% was added dropwise to adjust the pH of the system to 7.5. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 4% of aluminum hydroxide was added, and the reaction was carried out at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 20 wt%. Add 5% by mass of diphenylphosphonic chloride and 3% by mass of triethylamine to the aminated modified aluminum hydroxide. Stir and react at 30°C for 8 hours. After the reaction is completed, filter, wash, dry and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0045] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ to carry out deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and styrene is stirred and diluted to obtain the unsaturated polyester resin matrix. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 10MPa at 110℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0046] Comparative Example 2 Comparative Example 2 differs from Example 1 in that, while maintaining the molar ratio of total hydroxyl groups to total carboxyl groups and the total mass of the matrix resin monomers, only small molecule diols are used as the alcohol component, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 48.5 parts unsaturated dicarboxylic acid, 32.5 parts small molecule diol, 40 parts styrene, 20 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 10 parts organic phosphonate, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent.

[0047] The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organic phosphinate is zinc dimethylphosphinate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0048] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 8:1 to prepare a suspension with a solid content of 20wt%. Ammonia solution with a mass fraction of 5% was added dropwise to adjust the pH of the system to 7.5. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 4% of aluminum hydroxide was added, and the reaction was carried out at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 20 wt%. Add 5% by mass of diphenylphosphonic chloride and 3% by mass of triethylamine to the aminated modified aluminum hydroxide. Stir and react at 30°C for 8 hours. After the reaction is completed, filter, wash, dry and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0049] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ simultaneously for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 10MPa at 110℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0050] Comparative Example 3 Comparative Example 3 differs from Example 1 in that an equal mass of aminated modified aluminum hydroxide is used instead of phosphorus-nitrogen-silicon modified aluminum hydroxide, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 36 parts unsaturated dicarboxylic acid, 25 parts polymeric polyol, 20 parts small molecule diol, 40 parts styrene, 20 parts aminated modified aluminum hydroxide, 10 parts organic phosphonate, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent.

[0051] The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymeric polyol is polycaprolactone diol; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organic phosphonate is zinc dimethylphosphonate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0052] Aminated aluminum hydroxide is prepared by the following method: Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 8:1 to prepare a suspension with a solid content of 20 wt%. Ammonia solution with a mass fraction of 5% was added dropwise to adjust the pH of the system to 7.5. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 4% of aluminum hydroxide was added, and the reaction was carried out at 60°C for 2 h. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide.

[0053] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with aminated modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 10MPa at 110℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0054] Comparative Example 4 Comparative Example 4 differs from Example 1 in that it uses a phosphorus-based flame retardant to directly modify aluminum hydroxide, omitting the silane amination (S1) step, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 36 parts unsaturated dicarboxylic acid, 25 parts polymeric polyol, 20 parts small molecule diol, 40 parts styrene, 20 parts phosphorus-modified aluminum hydroxide, 10 parts organic phosphonate, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent; The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymeric polyol is polycaprolactone diol; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organic phosphonate is zinc dimethylphosphonate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0055] Phosphorus-modified aluminum hydroxide is prepared by the following method: Aluminum hydroxide was dispersed in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 20 wt%. Diphenylphosphonic chloride (5% by mass of aluminum hydroxide) and triethylamine (3% by mass of aluminum hydroxide) were added, and the mixture was stirred at 30 °C for 8 h. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain phosphorus-modified aluminum hydroxide.

[0056] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus-modified aluminum hydroxide and organic phosphonate, add curing agent, place in mold, and cure under molding pressure of 10MPa at 110℃ for 3h. After cooling and demolding, obtain halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell.

[0057] Comparative Example 5 Comparative Example 5 differs from Example 1 in that an equal mass of phosphorus-nitrogen-silicon modified aluminum hydroxide is used to replace the organic phosphonate, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 36 parts unsaturated dicarboxylic acid, 25 parts polymeric polyol, 20 parts small molecule diol, 40 parts styrene, 30 parts phosphorus-nitrogen-silicon modified aluminum hydroxide, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent.

[0058] The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymeric polyol is polycaprolactone diol; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0059] Phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Aluminum hydroxide was dispersed in an ethanol-water mixture with a volume ratio of 8:1 to prepare a suspension with a solid content of 20wt%. Ammonia solution with a mass fraction of 5% was added dropwise to adjust the pH of the system to 7.5. N-[3-(trimethoxysilyl)propyl]ethylenediamine with a mass fraction of 4% of aluminum hydroxide was added, and the reaction was carried out at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Disperse the aminated modified aluminum hydroxide obtained in step S1 in anhydrous tetrahydrofuran to prepare a suspension with a solid content of 20 wt%. Add 5% by mass of diphenylphosphonic chloride and 3% by mass of triethylamine to the aminated modified aluminum hydroxide. Stir and react at 30°C for 8 hours. After the reaction is completed, filter, wash, dry and sieve to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

[0060] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide, add the curing agent, place it in the mold, and cure it by molding at 110°C for 3 hours under a molding pressure of 10MPa. After cooling and demolding, a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shells is obtained.

[0061] Comparative Example 6 Comparative Example 6 differs from Example 1 in that an equal mass of organic phosphonate is used to replace the phosphorus-nitrogen-silicon modified aluminum hydroxide, as detailed below: A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings comprises the following components by weight: 36 parts unsaturated dicarboxylic acid, 25 parts polymeric polyol, 20 parts small molecule diol, 40 parts styrene, 30 parts organic phosphonates, 0.5 parts organometallic catalyst, 0.01 parts polymerization inhibitor, and 1.2 parts curing agent.

[0062] The unsaturated dicarboxylic acid is obtained by mixing maleic acid and 4,4'-stilbene dicarboxylic acid in a mass ratio of 2:1; the polymeric polyol is polycaprolactone diol; the small molecule diol is obtained by mixing ethylene glycol and 1,4-cyclohexanediethanol in a mass ratio of 1:1; the organic phosphonate is zinc dimethylphosphonate; the organometallic catalyst is dibutyltin oxide; the polymerization inhibitor is phenothiazine; and the curing agent is tert-butylperbenzoic acid.

[0063] A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, nitrogen gas is introduced to carry out the atmospheric pressure prepolymerization reaction. The temperature is raised to 170℃ within 1.5h, and the temperature is continued to be raised in a gradient. The temperature is raised to 190℃ within 4h. When the acid value of the system drops to 60mg KOH / g, the atmospheric pressure prepolymerization reaction is completed. Then, the pressure reduction reaction is carried out by gradient pressure reduction. The system pressure is reduced to 30kPa within 1h, the reaction temperature is maintained at 190℃, and the reaction is kept at this temperature for 1h. The pressure is further reduced to 5kPa, and the temperature is raised to 205℃ for deep pressure reduction polymerization until the acid value of the system drops to 20mg KOH / g. The reaction is stopped, the temperature is lowered to 90℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and the unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with the organic phosphonate, add the curing agent, place it in the mold, and cure it by molding at 110°C for 3 hours under a molding pressure of 10MPa. After cooling and demolding, a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casing is obtained.

[0064] The performance of the halogen-free flame-retardant unsaturated polyester resin materials for energy storage battery casings obtained in Examples 1-3 and Comparative Examples 1-6 of the present invention was tested, and the results are shown in Table 1. Oxygen index test: Refer to GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics"; UL94 vertical burning test: Refer to GB / T 2408-2021 "Combustion Performance of Plastics - Vertical Burning Method"; Smoke suppression performance (smoke density / DSmax) test: Refer to GB / T 8323.2-2008 "Plastics - Smoke Generation - Part 2: Test Method for Determination of Smoke Density by Single Chamber Method"; Tensile strength test: Refer to GB / T1049.1-2018 "Determination of Tensile Properties of Plastics"; Flexural strength test: Refer to GB / T 9341-2008 "Determination of Flexural Properties of Plastics"; Breakdown strength test: Refer to GB / T Tested according to 1408.1-2006 "Test Method for Electrical Strength of Insulating Materials"; High and low temperature cycling: -40℃~125℃, 50 cycles of alternating hot and cold temperatures, visually observe the appearance of the sample, no visible cracks after 50 cycles are considered qualified, and the appearance of fine cracks ≥0.1mm on the surface after 50 cycles is considered unqualified; the specific results are shown in Table 1.

[0065] Table 1:

[0066] As shown in the table above, Examples 1-3 are superior to Comparative Examples 1-6, meeting the mandatory requirements for flame retardancy, low smoke, structural strength, insulation, and wide temperature weather resistance of energy storage battery casings, and are suitable for long-term safe operation of large containers and industrial and commercial energy storage battery packs.

[0067] Comparative Examples 1, 1, and 2 show that, under the premise of strictly maintaining the molar ratio of the alkyd polycondensation reaction and the total mass of the matrix resin, changing the structure of the alcohol component has a significant impact on the mechanical and weather resistance properties of the material. Using only polymeric polyols leads to a significant decrease in resin crosslinking density and excessive flexibility of the molecular chains, resulting in severe deterioration of the material's mechanical strength and inability to meet the load-bearing requirements of the shell. While using only small-molecule diols can maintain high tensile strength, the high-density crosslinking results in excessive rigidity and brittleness, making it difficult to release internal residual stress. This makes the material prone to stress concentration and brittle cracking in alternating hot and cold environments. This invention rationally blends polymeric polyols with small-molecule diols, achieving synergistic control of the rigid and flexible segments of the resin main chain. This blended structure retains sufficient crosslinking density to maintain excellent structural strength while endowing the network with appropriate free volume and toughness, thus successfully overcoming the cracking defects under thermal shock and achieving both high mechanical strength and long-term dimensional stability.

[0068] Comparative Examples 1, 3, and 4 show that: single-step aminosilane modification alone lacks efficient grafting of phosphorus-based flame retardant elements, limiting the flame retardant and smoke suppression effects; single-step phosphorus modification alone, due to the lack of bridging effect of silane coupling agents, not only has low grafting efficiency but also extremely poor interfacial compatibility of the filler in the resin matrix, resulting in a significant decrease in mechanical strength and easy cracking under high and low temperature alternation; the phosphorus-nitrogen-silicon integrated modified aluminum hydroxide obtained by the two-step chemical grafting of this invention can improve the interfacial compatibility of the filler-matrix, simultaneously increase mechanical strength and flame retardancy, and significantly reduce combustion smoke.

[0069] Comparing Example 1, Comparative Example 5, and Comparative Example 6, it can be seen that: adding phosphorus-nitrogen-silicon modified aluminum hydroxide alone can only ensure resistance to high and low temperatures and basic mechanical properties, but the flame retardant rating is insufficient and the smoke release is too high; adding organic phosphonate alone reduces the toughness of the material and makes it prone to failure under thermal cycling; the combination of the two to construct a synergistic halogen-free flame retardant system, with the gas phase and condensed phase flame retardant mechanisms working together, can achieve V-0 high flame retardancy, low smoke, high strength, and temperature resistance simultaneously with low filler content. A single flame retardant component is difficult to achieve the best comprehensive performance balance.

[0070] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings, characterized in that, It comprises the following components by weight: 35-45 parts of unsaturated dicarboxylic acid, 15-30 parts of polymeric polyol, 15-25 parts of small molecule diol, 35-45 parts of styrene, 15-25 parts of phosphorus-nitrogen-silicon modified aluminum hydroxide, 8-15 parts of organic phosphonate, 0.5-2 parts of organometallic catalyst, 0.01-1 part of polymerization inhibitor, and 1.2-2.0 parts of curing agent.

2. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The unsaturated dicarboxylic acid includes at least one of maleic acid, fumaric acid, itaconic acid, pentene, hexene, and 4,4'-stilbene dicarboxylic acid.

3. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The polymer polyol includes at least one of polycaprolactone diol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether diol, and polycarbonate diol.

4. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The small molecule diols include at least two of ethylene glycol, 1,3-propanediol, 1,5-pentanediol, neopentanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, and 1,3-cyclohexanediol.

5. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The phosphorus-nitrogen-silicon modified aluminum hydroxide is prepared by the following method: S1. Disperse aluminum hydroxide in an ethanol-water mixed solvent to form a suspension with a solid content of 20-25 wt%. Adjust the pH of the system to 7.5-9.0, add N-[3-(trimethoxysilyl)propyl]ethylenediamine, and react at 60-70℃ for 2-4 h. The reaction product is filtered, washed, dried, and sieved to obtain aminated modified aluminum hydroxide. S2. Ammoniated modified aluminum hydroxide is dispersed in anhydrous tetrahydrofuran to form a suspension with a solid content of 20-30 wt%. Diphenylphosphonic chloride and triethylamine are added, and the mixture is stirred at 25-40℃ for 6-12 h. The reaction product is filtered, washed, dried, and sieved to obtain phosphorus-nitrogen-silicon modified aluminum hydroxide.

6. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 5, characterized in that, The mass of N-[3-(trimethoxysilyl)propyl]ethylenediamine is 4-8% of the mass of aluminum hydroxide; the mass of diphenylphosphonic chloride is 5-10% of the mass of aminated aluminum hydroxide; and the mass of triethylamine is 3-6% of the mass of aminated aluminum hydroxide. The volume ratio of the ethanol-water mixed solvent is 8 to 10:

1.

7. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The organic phosphonates include at least one of zinc dimethylphosphonate, zinc diethylphosphonate, aluminum diethylphosphonate, aluminum dimethylphosphonate, and aluminum phenylmethylphosphonate.

8. The halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 1, characterized in that, The organometallic catalyst includes at least one of dibutyltin oxide, antimony glycolate, and zinc acetate; the polymerization inhibitor includes at least one of phenothiazine, catechol, and tert-butylcatechol.

9. A method for preparing a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to any one of claims 1-8, characterized in that, Includes the following steps: Step (1) After mixing the unsaturated diacid, polymer polyol, small molecule diol, organometallic catalyst and 1 / 2 mass of polymerization inhibitor evenly, an inert gas is introduced to carry out a normal pressure prepolymerization reaction. When the acid value of the system drops to 60-80 mg KOH / g, the normal pressure prepolymerization reaction is completed. Then, a gradient decompression polymerization reaction is carried out until the acid value of the system drops to 20-40 mg KOH / g. The reaction is stopped, the temperature is lowered to 90-110℃, the remaining polymerization inhibitor is added and stirred with styrene to dilute, and an unsaturated polyester resin matrix is ​​obtained. Step (2) After uniformly mixing the unsaturated polyester resin matrix with phosphorus nitrogen silicon modified aluminum hydroxide and organic phosphonate, add curing agent, place it in the mold, and cure it under molding pressure of 10-15MPa at 110-130℃ for 3 hours. After cooling and demolding, a halogen-free flame-retardant unsaturated polyester resin material for energy storage battery shell is obtained.

10. The method for preparing the halogen-free flame-retardant unsaturated polyester resin material for energy storage battery casings according to claim 9, characterized in that, The heating program for the atmospheric pressure prepolymerization reaction in step (1) is as follows: the temperature is raised to 160-170°C within 1.5 hours, and the temperature is continued to rise in a gradient, raising the temperature to 180-190°C within a total of 4 hours. The pressure reduction polymerization described in step (1) adopts a gradient pressure reduction process: after the atmospheric pressure prepolymerization reaction is completed, the system pressure is reduced to 30-50 kPa within 1 hour, the reaction temperature is maintained at 190-200℃, and the reaction is kept at the temperature for 1-2 hours; then the pressure is further reduced to 5-15 kPa, and the temperature is simultaneously raised to 205-215℃ for deep pressure reduction polymerization.

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