High-strength flame-retardant battery pack shell and preparation method thereof

Abstract

The invention discloses a high-strength flame-retardant battery pack shell and a preparation method thereof, and relates to the technical field of battery pack shell materials. The high-strength flame-retardant battery pack shell disclosed by the invention is prepared by coating a glass fiber mat with composite polyurethane; the composite polyurethane comprises modified polyurethane and flame-retardant particles, the flame-retardant particles are prepared by grafting epoxy phosphoryl succinic acid on the surface of aminated silicon dioxide, the epoxy phosphoryl succinic acid is prepared by reacting diphenyl phosphine oxide, maleic acid and long-chain hydroxyl diphenyl sulfide, and the long-chain hydroxyl diphenyl sulfide is 4, 4 '-diphenylphosphine oxide. The flame retardant is prepared by reacting 4, 4 '-dihydroxy diphenyl sulfide with epoxy chloropropane, and is added into the modified polyurethane, so that the flame retardant property of the battery pack shell is enhanced; the modified polyurethane is prepared by reacting hydroxyl polyphenyl ether, hydroxyl fluorosilicone oil and toluene diisocynate to prepare a modified polyurethane prepolymer, and then reacting the modified polyurethane prepolymer with a fluorine-containing chain extender for chain extension; the fluorine-containing chain extender is prepared by reacting cyanuric chloride, octafluoropentanol and ethanolamine, and the strength of the modified polyurethane is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pack shell materials, and specifically to a high-strength flame-retardant battery pack shell and a preparation method thereof. Background Art

[0002] The power battery system (battery pack) is the power source of the whole new energy vehicle and one of the most critical components of new energy vehicles. The battery pack is generally composed of battery modules, electrical systems, thermal management systems, battery management systems and structural parts. The main function of the power battery pack shell is to carry the power battery system components such as battery modules, electrical modules, cooling modules, etc. At the same time, it protects the battery and electrical system from being damaged by external collisions and extrusions. It plays a vital role in the safety protection of the battery pack. In order to ensure the safety of the power battery, the power battery pack shell needs to adapt to various complex working conditions and meet the requirements of strength and rigidity.

[0003] At present, most pure electric vehicles use steel or aluminum alloy materials as the protective shell of the battery pack to ensure the safety of the chassis power battery. To a large extent, the safety of the power battery can be protected, but it also faces the problem of heavy weight of the battery pack, meaningless increase in curb weight, increased power consumption, reduced endurance, and even varying degrees of impact on vehicle control. With the development of energy conservation, environmental protection and lightweight of automobiles, lightweight material options such as mica sheets or heat-resistant ceramic fibers have also appeared in battery shell materials, but they still cannot meet the safety of current battery use; therefore, the present invention studies and prepares a high-strength flame-retardant battery pack shell with excellent flame retardancy and mechanical properties. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a battery pack shell made of a high-strength flame-retardant battery pack shell, which has excellent flame retardancy and mechanical properties.

[0005] The present invention proposes a technical solution to solve the above technical problems: a high-strength flame-retardant battery pack shell is made of glass fiber felt coated with composite polyurethane; the composite polyurethane includes modified polyurethane and flame-retardant particles; the flame-retardant particles are made by grafting epoxyphosphorylsuccinic acid on the surface of amino silica; the modified polyurethane is made by reacting hydroxy polyphenyl ether, hydroxy fluorosilicone oil and toluene diisocyanate to obtain a modified polyurethane prepolymer, and then reacting with a fluorine-containing chain extender to extend the chain.

[0006] Preferably, the epoxyphosphinosuccinic acid is prepared by reacting diphenylphosphine oxide, maleic acid and long-chain hydroxydiphenyl sulfide; and the long-chain hydroxydiphenyl sulfide is prepared by reacting 4,4′-dihydroxydiphenyl sulfide and epichlorohydrin.

[0007] Preferably, the fluorine-containing chain extender is prepared by reacting cyanuric chloride, octafluoropentanol and ethanolamine.

[0008] Preferably, the method for preparing the high-strength flame-retardant battery pack shell comprises the following specific steps:

[0009] S1. Under a nitrogen atmosphere, 4,4′-dihydroxydiphenyl sulfide and epichlorohydrin are mixed in a mass ratio of 1:0.8-1.2, stirred and dissolved, and tetra-n-butylammonium bromide of 0.2-0.4 times the mass of epichlorohydrin is added, the temperature is raised to 70-90°C, the reaction is carried out for 20-40 minutes, the epichlorohydrin is recovered under reduced pressure, and then toluene of the same mass as 4,4′-dihydroxydiphenyl sulfide and phosphophosphonic acid of 1.6-1.8 times the mass of 4,4′-dihydroxydiphenyl sulfide are added, the reaction is continued for 4-6 hours, the mixture is filtered and washed with deionized water for 3-5 times, and the epoxyphosphophosphonic acid is distilled under reduced pressure to obtain epichlorohydrin;

[0010] S2. Under a nitrogen atmosphere, epoxyphosphoryl succinic acid, amino silica and dichloroethane were mixed in a mass ratio of 5:2 to 3:20 to 30, stirred evenly, and triethylamine was added in an amount of 0.4 to 0.6 times the mass of epoxyphosphoryl succinic acid, the temperature was raised to 80 to 90 ° C, the reaction was stirred at 400 to 800 rpm for 22 to 26 hours, centrifuged and washed with dichloroethane 3 to 5 times to obtain flame retardant particles;

[0011] S3. Mix hydroxy polyphenylene ether and hydroxy fluorosilicone oil in a mass ratio of 1:0.4-0.8, heat to 100-110° C., vacuum dehydrate to a moisture content of 0.02-0.05%, cool to 40-50° C., add dibutyltin dilaurate in an amount of 0.01-0.02 times the mass of hydroxy polyphenylene ether and toluene diisocyanate in an amount of 1.4-1.8 times the mass of hydroxy polyphenylene ether, heat to 75-85° C., and keep warm for 4-6 hours to obtain a polyurethane prepolymer;

[0012] S4. After the polyurethane prepolymer is stirred for 20 to 40 minutes, vacuum degassing is performed, 0.12 to 0.14 times the mass of the polyurethane prepolymer is added with a fluorine-containing chain extender, and after stirring at 600 to 800 rpm for 20 to 40 minutes, vacuum degassing is performed, and room temperature vulcanization is performed for 6 to 7 days to obtain a modified polyurethane;

[0013] S5. The modified polyurethane, flame retardant particles and tetrahydrofuran are mixed in a mass ratio of 5 to 8: 0.2 to 0.6: 100, stirred at 1000 to 2000 rpm for 18 to 24 h, and then dried in a vacuum drying oven at 50 to 60 ° C to obtain a composite polyurethane;

[0014] S6. Electric-cut the glass fiber, stack the cut glass fiber cloth, staple the edges with a stapler, clamp and send it into the spray room, place the metal part in the mold sprayed with release agent, mix the composite polyurethane and water in a mass ratio of 20-40:1-3 in a foaming machine, spray it on the glass fiber cloth with a spray gun, heat the mold to 175-185°C, place the sprayed glass fiber on the metal part, close the mold, pressurize it to 100-120MPa, remove the mold after hot pressing for 5-7 minutes, and perform post-processing to obtain a high-strength flame-retardant battery pack shell.

[0015] Preferably, in the above step S1., the preparation method of phosphoinosuccinic acid is: under a nitrogen atmosphere, diphenylphosphine oxide, maleic acid and propionic acid are mixed in a mass ratio of 3.8-4.2:3:40, the temperature is raised to 80-90°C, the reaction is stirred at 400-800rpm for 18-22h, and the mixture is rotary evaporated and successively treated with ethanol and acetic acid 3-5 times, and then dissolved in a potassium hydroxide solution with a mass fraction of 4-8%, and 1-2 mol / l hydrochloric acid is added for precipitation, and finally washed with ethanol 3-5 times, and dried in a vacuum drying oven at 60°C to obtain phosphoinosuccinic acid.

[0016] Preferably, in the above step S2., the preparation method of amino silica is: ethanol and ammonia water with a mass fraction of 10 to 30% are mixed in a mass ratio of 20:0.8 to 1.2, the temperature is raised to 40 to 42 ° C, and ammonia water is added with an equal mass of ethyl orthosilicate, and the reaction is stirred at 200 to 600 rpm for 10 to 12 hours, and then KH-550 with a mass of 0.12 to 0.16 times the mass of ammonia water is added, and the reaction is continued for 5 to 6 hours, and then the temperature is raised to 78 to 82 ° C, reflux reaction for 2 to 3 hours, centrifuged, washed with ethanol and dichloromethane for 3 to 5 times in sequence, and dried to obtain amino silica.

[0017] Preferably, in the above step S3., the preparation method of hydroxypolyphenylene ether is: 2,6-dimethylphenol, 2,2',4,4'-tetramethylbisphenol A and toluene are mixed in a mass ratio of 1:10 to 12:50, stirred and dissolved, and then 0.1 to 0.2 times the mass of 2,6-dimethylphenol copper chloride and 0.25 to 0.35 times the mass of 2,6-dimethylphenol-dimethylaminopyridine are added, the temperature is raised to 40 to 42 ° C, oxygen is continuously passed at a rate of 4 to 6 ml / min, and after reacting for 3 to 6 hours, the reaction is quenched with acetic acid to terminate the reaction, and then separated and filtered with saturated brine, dried with anhydrous sodium sulfate, distilled under reduced pressure, precipitated with methanol and filtered, and then washed with methanol 3 to 5 times, and vacuum dried at 80 ° C to obtain hydroxypolyphenylene ether.

[0018] Preferably, in the above step S4., the preparation method of the fluorine-containing chain extender is: cyanuric chloride, acetone and deionized water are mixed in a mass ratio of 1:3 to 6:3, and at the same time, an acetone solution of octafluoropentanol with a mass fraction of 1 to 4% and a sodium hydroxide solution with a mass fraction of 2.6 to 2.9 times the mass of cyanuric chloride and a mass fraction of 8 to 10% are added dropwise at a rate of 1 to 3 ml / min, reacting at room temperature for 3 to 6 hours, heating to 42 to 48 ° C, adding cyanuric chloride with a mass fraction of 1.2 to 1.4 times the mass of cyanuric chloride, and adding acetone solution with a mass fraction of 1 to 4%. 0.3-0.4 times the mass of ethanolamine and 2.6-2.9 times the mass of cyanuric chloride with a mass fraction of 8-10% sodium hydroxide solution, continue to react for 3-5 hours, heat to 92-98°C, add 0.3-0.4 times the mass of ethanolamine and 2.6-2.9 times the mass of cyanuric chloride with a mass fraction of 8-10% sodium hydroxide solution again, continue to react for 6-8 hours, cool to room temperature, filter and wash with acetone and deionized water for 3-5 times, and vacuum dry to obtain a fluorine-containing chain extender.

[0019] Preferably, in the above step S6., the spray gun pressure is 130-150 MPa, and the spraying time is 2-4 seconds; the metal part is an aluminum metal part or an iron metal part; and the release agent is a mixture of 36-40% by mass of polysiloxane and 60-64% by mass of water.

[0020] Preferably, in the above step S6., the post-processing process is as follows: opening holes, washing with tap water, air drying, air tightness testing, and finally packaging.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] The high-strength flame-retardant battery pack shell prepared by the present invention is prepared by coating glass fiber felt with composite polyurethane; the composite polyurethane includes modified polyurethane and flame-retardant particles;

[0023] The flame retardant particles are prepared by grafting epoxyphosphinosuccinic acid on the surface of amino silica. Epoxyphosphinosuccinic acid is prepared by the reaction of diphenylphosphine oxide, maleic acid and long-chain hydroxydiphenyl sulfide. Long-chain hydroxydiphenyl sulfide is prepared by the reaction of 4,4′-dihydroxydiphenyl sulfide and epichlorohydrin. When 4,4′-dihydroxydiphenyl sulfide reacts with epichlorohydrin, the ring is opened to form a long-chain hydroxydiphenyl sulfide with a symmetrical structure, a part of which reacts with the phosphoryl succinic acid generated by the reaction of diphenylphosphine oxide and maleic acid, and a part of which is closed to form an epoxy group, which is grafted to the amino silica to form flame retardant particles with a long-chain structure on the surface, which are added to the modified polyurethane to enhance the flame retardant properties of the battery pack shell;

[0024] The modified polyurethane is prepared by reacting hydroxy polyphenyl ether, hydroxy fluorosilicone oil and toluene diisocyanate to obtain a modified polyurethane prepolymer, which is then reacted with a fluorine-containing chain extender for chain extension. The fluorine-containing chain extender is prepared by reacting cyanuric chloride, octafluoropentanol and ethanolamine. Fluorosilicone oil is introduced into the polyurethane to form a modified polyurethane prepolymer with a long-chain structure, which is then extended with the chain extender to further enhance the hydrophobicity and the strength of the modified polyurethane. The composite polyurethane is then coated with glass fiber felt to produce a battery pack shell with excellent flame retardancy. DETAILED DESCRIPTION

[0025] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention. Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art.

[0026] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the high-strength flame-retardant battery pack shell prepared in the examples and comparative examples as follows:

[0027] Flame retardancy: The high-strength flame-retardant battery pack shells prepared in the examples and comparative examples were subjected to oxygen index measurement in accordance with GB / T2406.2.

[0028] Tensile strength: The high-strength flame-retardant battery pack shells prepared in the examples and comparative examples were subjected to a tensile strength test in accordance with GB / T1040.

[0029] Air tightness: The high-strength flame-retardant battery pack shells prepared in the examples and comparative examples were subjected to airtight direct pressure testing with reference to GB4208.

[0030] Example 1

[0031] The preparation method of the high-strength flame-retardant battery pack shell in this embodiment is:

[0032] S1. In a nitrogen atmosphere, diphenylphosphine oxide, maleic acid and propionic acid were mixed in a mass ratio of 3.8:3:40, heated to 80°C, stirred at 400rpm for 18h, rotary evaporated and washed with ethanol and acetic acid three times in sequence, dissolved in a 4% potassium hydroxide solution, 1 mol / l hydrochloric acid was added for precipitation, washed with ethanol three times, and dried in a vacuum drying oven at 60°C to obtain phospho-succinic acid; in a nitrogen atmosphere, 4,4′- Dihydroxydiphenyl sulfide and epichlorohydrin are mixed in a mass ratio of 1:0.8, stirred and dissolved, and then 0.2 times the mass of tetra-n-butylammonium bromide of epichlorohydrin is added, the temperature is raised to 70°C, the reaction is carried out for 20 minutes, the epichlorohydrin is recovered under reduced pressure, and then toluene of the same mass as 4,4′-dihydroxydiphenyl sulfide and 1.6 times the mass of phospho-succinic acid of 4,4′-dihydroxydiphenyl sulfide are added, the reaction is continued for 4 hours, the mixture is filtered and washed with deionized water for 3 times, and the epoxyphospho-succinic acid is distilled under reduced pressure to obtain epichlorohydrin;

[0033] S2. Ethanol and 10% ammonia water were mixed in a mass ratio of 20:0.8, heated to 40°C, and an equal mass of tetraethyl orthosilicate was added to ammonia water. The mixture was stirred at 200 rpm for 10 hours, and then 0.12 times the mass of KH-550 of ammonia water was added. After the reaction was continued for 5 hours, the mixture was heated to 78°C, refluxed for 2 hours, centrifuged, washed with ethanol and dichloromethane three times in sequence, and dried to obtain amino silica; under a nitrogen atmosphere, epoxyphosphorylsuccinic acid, amino silica and dichloroethane were mixed in a mass ratio of 5:2:20, stirred evenly, and triethylamine was added in an amount of 0.4 times the mass of epoxyphosphorylsuccinic acid, heated to 80°C, stirred at 400 rpm for 22 hours, centrifuged, and washed with dichloroethane three times to obtain flame retardant particles;

[0034] S3. Mix 2,6-dimethylphenol, 2,2',4,4'-tetramethylbisphenol A and toluene in a mass ratio of 1:10:50, stir and dissolve, add 0.1 times the mass of copper chloride and 0.25 times the mass of dimethylaminopyridine of 2,6-dimethylphenol, heat to 40°C, continue to pass oxygen at a rate of 4 ml / min, react for 3 hours, quench with acetic acid to terminate the reaction, separate with saturated brine, filter, and dry with anhydrous sodium sulfate , distill under reduced pressure, precipitate with methanol and filter, wash with methanol three times, and vacuum dry at 80°C to obtain hydroxy polyphenyl ether; mix hydroxy polyphenyl ether and hydroxy fluorosilicone oil in a mass ratio of 1:0.4, heat to 100°C, vacuum dehydrate to a moisture content of 0.02%, cool to 40°C, add dibutyltin dilaurate (0.01 times the mass of hydroxy polyphenyl ether) and toluene diisocyanate (1.4 times the mass of hydroxy polyphenyl ether), heat to 75°C, and keep warm for 4 hours to obtain a polyurethane prepolymer;

[0035] S4. Mix cyanuric chloride, acetone and deionized water in a mass ratio of 1:3:3, and simultaneously add 1% octafluoropentanol acetone solution (1.2 times the mass of cyanuric chloride) and 8% sodium hydroxide solution (2.6 times the mass of cyanuric chloride) at a rate of 1 ml / min. After reacting at room temperature for 3 hours, heat to 42°C, add ethanolamine (0.3 times the mass of cyanuric chloride) and 8% sodium hydroxide solution (2.6 times the mass of cyanuric chloride), continue to react for 3 hours, and heat to 92°C. ℃, add ethanolamine with a mass fraction of 0.3 times that of cyanuric chloride and sodium hydroxide solution with a mass fraction of 8% with a mass fraction of 2.6 times that of cyanuric chloride again, continue to react for 6 hours, cool to room temperature, filter and wash with acetone and deionized water for 3 times, and vacuum dry to obtain a fluorine-containing chain extender; stir the polyurethane prepolymer for 20 minutes, vacuum degassing, add fluorine-containing chain extender with a mass fraction of 0.12 times that of the polyurethane prepolymer, stir at 600rpm for 20 minutes, vacuum degassing, and vulcanize at room temperature for 6 days to obtain a modified polyurethane;

[0036] S5. The modified polyurethane, flame retardant particles and tetrahydrofuran were mixed in a mass ratio of 5:0.2:100, stirred at 1000 rpm for 18 h, and then dried in a vacuum oven at 50 ° C to obtain a composite polyurethane;

[0037] S6. Electric-cut the glass fiber, stack the cut glass fiber cloth, staple the edges with a stapler, clamp and send it into the spray room, place the aluminum metal part in the mold sprayed with a release agent, the release agent is a mixture of 36% by mass of polysiloxane and 64% by mass of water, mix the composite polyurethane and water in a mass ratio of 20:1 and place it in a foaming machine, spray it on the glass fiber cloth with a spray gun, the spray gun pressure is 130MPa, spray for 2s, heat the mold to 175℃, place the sprayed glass fiber on the metal part, close the mold, pressurize it to 100MPa, remove the mold after hot pressing for 5min, and perform post-processing. The post-processing process is as follows: opening holes, water washing with tap water, air drying, air tightness testing, and finally packaging to obtain a high-strength flame-retardant battery pack shell.

[0038] Example 2

[0039] The preparation method of the high-strength flame-retardant battery pack shell in this embodiment is:

[0040] S1. In a nitrogen atmosphere, diphenylphosphine oxide, maleic acid and propionic acid were mixed in a mass ratio of 4:3:40, heated to 85°C, stirred at 600rpm for 20h, rotary evaporated and used ethanol and acetic acid 4 times in sequence, then dissolved in a 6% potassium hydroxide solution, 1-2 mol / l hydrochloric acid was added for precipitation, and finally washed with ethanol 4 times and dried in a vacuum drying oven at 60°C to obtain phospho-succinic acid; in a nitrogen atmosphere, 4,4′ -Dihydroxydiphenyl sulfide and epichlorohydrin are mixed in a mass ratio of 1:1, stirred and dissolved, and tetra-n-butylammonium bromide with a mass of 0.3 times that of epichlorohydrin is added, the temperature is raised to 80°C, the reaction is carried out for 30 minutes, the epichlorohydrin is recovered under reduced pressure, and then toluene with a mass equal to that of 4,4′-dihydroxydiphenyl sulfide and phospho-succinic acid with a mass of 1.7 times that of 4,4′-dihydroxydiphenyl sulfide are added, the reaction is continued for 5 hours, the mixture is filtered and washed with deionized water for 4 times, and the epoxyphospho-succinic acid is distilled under reduced pressure to obtain epoxyphospho-succinic acid;

[0041] S2. Ethanol and 20% ammonia water were mixed in a mass ratio of 20:1, heated to 41°C, ammonia water was added with an equal mass of tetraethyl orthosilicate, stirred at 400rpm for 11h, and then KH-550 with a mass of 0.14 times the mass of ammonia water was added. After continuing the reaction for 5.5h, the temperature was raised to 80°C, refluxed for 2.4h, centrifuged, washed with ethanol and dichloromethane 4 times in sequence and dried to obtain amino silica; under a nitrogen atmosphere, epoxyphosphorylsuccinic acid, amino silica and dichloroethane were mixed in a mass ratio of 5:2.5:25, stirred evenly, and triethylamine with a mass of 0.5 times the mass of epoxyphosphorylsuccinic acid was added, heated to 85°C, stirred at 600rpm for 24h, centrifuged and washed with dichloroethane 4 times to obtain flame retardant particles;

[0042] S3. Mix 2,6-dimethylphenol, 2,2',4,4'-tetramethylbisphenol A and toluene in a mass ratio of 1:11:50, stir and dissolve, add 0.15 times the mass of copper chloride and 0.3 times the mass of dimethylaminopyridine of 2,6-dimethylphenol, heat to 41°C, continue to pass oxygen at a rate of 5 ml / min, react for 4.5 hours, quench with acetic acid to terminate the reaction, separate with saturated brine, filter, and dry with anhydrous sodium sulfate , distill under reduced pressure, precipitate with methanol and filter, wash with methanol 4 times, and vacuum dry at 80°C to obtain hydroxy polyphenyl ether; mix hydroxy polyphenyl ether and hydroxy fluorosilicone oil in a mass ratio of 1:0.6, heat to 105°C, vacuum dehydrate to a moisture content of 0.04%, cool to 45°C, add dibutyltin dilaurate (0.015 times the mass of hydroxy polyphenyl ether) and toluene diisocyanate (1.6 times the mass of hydroxy polyphenyl ether), heat to 80°C, and keep warm for 5 hours to obtain a polyurethane prepolymer;

[0043] S4. Mix cyanuric chloride, acetone and deionized water in a mass ratio of 1:4.5:3, and simultaneously add 3% octafluoropentanol acetone solution (1.3 times the mass of cyanuric chloride) and 9% sodium hydroxide solution (2.8 times the mass of cyanuric chloride) at a rate of 1-3 ml / min. After reacting at room temperature for 5 hours, heat to 45°C, add ethanolamine (0.35 times the mass of cyanuric chloride) and 9% sodium hydroxide solution (2.75 times the mass of cyanuric chloride), continue to react for 4 hours, and heat to 9. 5°C, adding ethanolamine with a mass fraction of 0.35 times that of cyanuric chloride and sodium hydroxide solution with a mass fraction of 9% with a mass fraction of 2.75 times that of cyanuric chloride again, continuing the reaction for 7 hours, cooling to room temperature, filtering and washing with acetone and deionized water for 4 times, and vacuum drying to obtain a fluorine-containing chain extender; stirring the polyurethane prepolymer for 30 minutes, vacuum degassing, adding a fluorine-containing chain extender with a mass fraction of 0.13 times that of the polyurethane prepolymer, stirring at 700 rpm for 30 minutes, vacuum degassing, and vulcanizing at room temperature for 6.5 days to obtain a modified polyurethane;

[0044] S5. The modified polyurethane, flame retardant particles and tetrahydrofuran were mixed in a mass ratio of 6:0.4:100, stirred at 1500 rpm for 21 h, and then dried in a vacuum oven at 55 ° C to obtain a composite polyurethane;

[0045] S6. Electric-cut the glass fiber, stack the cut glass fiber cloth, staple the edges with a stapler, clamp and send it into the spray room, place the iron metal parts in the mold sprayed with the release agent, the release agent is a mixture of 38% by mass of polysiloxane and 62% by mass of water, mix the composite polyurethane and water in a mass ratio of 30:2 and place them in a foaming machine, spray it on the glass fiber cloth with a spray gun, the spray gun pressure is 140MPa, spray for 3s, heat the mold to 180℃, place the sprayed glass fiber on the metal part, close the mold, pressurize it to 110MPa, remove the mold after hot pressing for 6min, and perform post-processing. The post-processing process is as follows: opening holes, water spraying and cleaning with tap water, air drying, air tightness testing, and finally packaging to obtain a high-strength flame-retardant battery pack shell.

[0046] Example 3

[0047] The preparation method of the high-strength flame-retardant battery pack shell in this embodiment is:

[0048] S1. In a nitrogen atmosphere, diphenylphosphine oxide, maleic acid and propionic acid were mixed in a mass ratio of 4.2:3:40, heated to 90°C, stirred at 800rpm for 22h, rotary evaporated and used ethanol and acetic acid 5 times in sequence, dissolved in a potassium hydroxide solution with a mass fraction of 8%, added with 2mol / l hydrochloric acid for precipitation, finally washed with ethanol 5 times, and dried in a vacuum drying oven at 60°C to obtain phospho-succinic acid; in a nitrogen atmosphere, 4,4′- Dihydroxydiphenyl sulfide and epichlorohydrin are mixed in a mass ratio of 1:1.2, stirred and dissolved, and then 0.4 times the mass of tetra-n-butylammonium bromide of epichlorohydrin is added, the temperature is raised to 90°C, the reaction is carried out for 40 minutes, the epichlorohydrin is recovered under reduced pressure, and then toluene of the same mass as 4,4′-dihydroxydiphenyl sulfide and 1.8 times the mass of phospho-succinic acid of 4,4′-dihydroxydiphenyl sulfide are added, the reaction is continued for 6 hours, the mixture is filtered and washed with deionized water for 5 times, and the epoxyphospho-succinic acid is distilled under reduced pressure to obtain epichlorohydrin;

[0049] S2. Ethanol and 30% ammonia water were mixed in a mass ratio of 20:1.2, heated to 42°C, and an equal mass of tetraethyl orthosilicate was added to ammonia water. The mixture was stirred at 600 rpm for 12 hours, and then 0.16 times the mass of KH-550 of ammonia water was added. After the reaction was continued for 6 hours, the mixture was heated to 82°C, refluxed for 3 hours, centrifuged, washed with ethanol and dichloromethane 5 times in sequence, and dried to obtain amino silica; under a nitrogen atmosphere, epoxyphosphorylsuccinic acid, amino silica and dichloroethane were mixed in a mass ratio of 5:3:30, stirred evenly, and triethylamine 0.6 times the mass of epoxyphosphorylsuccinic acid was added, the mixture was heated to 90°C, stirred at 800 rpm for 26 hours, centrifuged, and washed with dichloroethane 5 times to obtain flame retardant particles;

[0050] S3. Mix 2,6-dimethylphenol, 2,2',4,4'-tetramethylbisphenol A and toluene in a mass ratio of 1:12:50, stir and dissolve, add 0.2 times the mass of copper chloride of 2,6-dimethylphenol and 0.35 times the mass of dimethylaminopyridine of 2,6-dimethylphenol, heat to 42°C, continue to pass oxygen at a rate of 6 ml / min, react for 6 hours, quench with acetic acid to terminate the reaction, separate with saturated brine, filter, and dry with anhydrous sodium sulfate , distill under reduced pressure, precipitate with methanol and filter, wash with methanol 5 times, and vacuum dry at 80°C to obtain hydroxy polyphenyl ether; mix hydroxy polyphenyl ether and hydroxy fluorosilicone oil in a mass ratio of 1:0.8, heat to 110°C, vacuum dehydrate to a moisture content of 0.05%, cool to 50°C, add dibutyltin dilaurate (0.02 times the mass of hydroxy polyphenyl ether) and toluene diisocyanate (1.8 times the mass of hydroxy polyphenyl ether), heat to 85°C, keep warm for 6 hours to obtain a polyurethane prepolymer;

[0051] S4. Mix cyanuric chloride, acetone and deionized water in a mass ratio of 1:6:3, and simultaneously add 4% octafluoropentanol in acetone solution (1.4 times the mass of cyanuric chloride) and 10% sodium hydroxide solution (2.9 times the mass of cyanuric chloride) at a rate of 3 ml / min. After reacting at room temperature for 6 hours, heat to 48°C, add ethanolamine (0.4 times the mass of cyanuric chloride) and 10% sodium hydroxide solution (2.9 times the mass of cyanuric chloride), continue to react for 5 hours, and heat to 9 8°C, adding ethanolamine with a mass fraction of 0.4 times that of cyanuric chloride and sodium hydroxide solution with a mass fraction of 10% with a mass fraction of 2.9 times that of cyanuric chloride again, continuing the reaction for 8 hours, cooling to room temperature, filtering and washing with acetone and deionized water for 5 times, and vacuum drying to obtain a fluorine-containing chain extender; stirring the polyurethane prepolymer for 40 minutes, vacuum degassing, adding a fluorine-containing chain extender with a mass fraction of 0.14 times that of the polyurethane prepolymer, stirring at 800 rpm for 40 minutes, vacuum degassing, and vulcanizing at room temperature for 7 days to obtain a modified polyurethane;

[0052] S5. The modified polyurethane, flame retardant particles and tetrahydrofuran were mixed in a mass ratio of 8:0.6:100, stirred at 2000 rpm for 24 h, and then dried in a vacuum oven at 60 ° C to obtain a composite polyurethane;

[0053] S6. Electric-cut the glass fiber, stack the cut glass fiber cloth, staple the edges with a stapler, clamp and send it into the spray room, place the iron metal parts in the mold sprayed with the release agent, the release agent is a mixture of 40% by mass of polysiloxane and 60% by mass of water, mix the composite polyurethane and water in a mass ratio of 40:3 and place them in a foaming machine, spray it on the glass fiber cloth with a spray gun, the spray gun pressure is 150MPa, spray for 4s, heat the mold to 185℃, place the sprayed glass fiber on the metal part, close the mold, pressurize it to 120MPa, remove the mold after hot pressing for 7min, and perform post-processing. The post-processing process is as follows: opening holes, water washing with tap water, air drying, air tightness testing, and finally packaging to obtain a high-strength flame-retardant battery pack shell.

[0054] Comparative Example 1

[0055] The preparation method of comparative example 1 is the same as that of example 2. The difference between the high-strength flame-retardant battery pack shell and example 2 is that the flame-retardant particles are prepared by grafting phospho-succinic acid on the surface of amino-silica, and the phospho-succinic acid is prepared by reacting diphenylphosphine oxide with maleic acid.

[0056] Comparative Example 2

[0057] The preparation method of Comparative Example 2 is the same as that of Example 2. The difference between the high-strength flame-retardant battery pack shell and Example 2 is that the flame-retardant particles are only amino-silicon dioxide.

[0058] Comparative Example 3

[0059] The preparation method of Comparative Example 3 is the same as that of Example 2. The difference between the high-strength flame-retardant battery pack shell and Example 2 is that the chain extender is ethylene glycol.

[0060] Comparative Example 4

[0061] The preparation method of Comparative Example 4 is the same as that of Example 2. The difference between the high-strength flame-retardant battery pack shell and Example 2 is that the modified polyurethane prepolymer is prepared by reacting hydroxy polyphenylene ether and toluene diisocyanate.

[0062] Comparative Example 5

[0063] The preparation method of comparative example 5 is the same as that of example 2. The difference between the high-strength flame-retardant battery pack shell and example 2 is that the modified polyurethane prepolymer is prepared by reacting hydroxy fluorosilicone oil and toluene diisocyanate.

[0064] Effect example

[0065] Tables 1 and 2 below show the performance analysis results of the high-strength flame-retardant battery pack shells prepared using Examples 1 to 3 of the present invention and Comparative Examples 1 to 5:

[0066] Table 1

[0067] Oxygen index (%) Tensile strength(MPa) Oxygen index (%) Tensile strength(MPa) Example 1 30.1 350 Comparative Example 2 25.9 349 Example 2 31.7 357 Comparative Example 3 26.9 298 Example 3 30.5 352 Comparative Example 4 29.8 289 Comparative Example 1 27.5 347 Comparative Example 5 28.5 281

[0068] Table 2

[0069] Inflation pressure P / kPa <![CDATA[Balanced pressure P2 / kPa]]> <![CDATA[Detection time T3 / min]]> Example 1 4.0 3.0～3.5 1.0 Example 2 4.0 3.0～3.6 1.0 Example 3 4.0 3.0～3.5 1.0 Domestic car A 4.0 3.0～3.5 1.0 Domestic car B 3.5 3.0～3.5 8.0

[0070] Foreign automobile sealing performance requirements: 2.5~3kpa, restart for 60s, maintain pressure for 60s, test for 55s, leakage <5cc / min.

[0071] By comparing the experimental data of the embodiments and the comparative examples in Table 1 and Table 2, it can be clearly found that the high-strength flame-retardant battery pack shell prepared using Examples 1, 2, and 3 has excellent flame retardancy and mechanical properties.

[0072] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, it can be found that diphenylphosphine oxide, maleic acid and long-chain hydroxydiphenyl sulfide are reacted to obtain epoxyphosphorylsuccinic acid, which is grafted on the surface of amino-silica. When 4,4′-dihydroxydiphenyl sulfide reacts with epichlorohydrin, it opens the ring to form a long-chain hydroxydiphenyl sulfide with a symmetrical structure, part of which reacts with the phosphorylsuccinic acid generated by the reaction of diphenylphosphine oxide and maleic acid, and part of it closes the ring to form an epoxy group, which is grafted to the amino-silica to form flame-retardant particles with a long-chain structure on the surface. The particles are added to the modified polyurethane to enhance the flame retardant properties of the battery pack shell.

[0073] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 3, Comparative Example 4, it can be found that after the modified polyurethane prepolymer is prepared by reacting polyphenylene ether, hydroxyl fluorosilicone oil and toluene diisocyanate, the modified polyurethane is obtained by reacting with a fluorine-containing chain extender for chain extension, fluorosilicone oil is introduced into the polyurethane to form a modified polyurethane prepolymer with a long-chain structure, and then the chain is extended with the chain extender to further enhance the hydrophobicity and the strength of the modified polyurethane; the composite polyurethane is then coated with glass fiber felt to prepare a battery pack shell having excellent flame retardancy and mechanical properties.

[0074] Obviously, the above embodiments are merely examples for clearly illustrating the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. However, these obvious changes or modifications derived from the spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. A high-strength flame-retardant battery pack shell, characterized in that The composite polyurethane is prepared by coating glass fiber felt; the composite polyurethane comprises modified polyurethane and flame retardant particles; the flame retardant particles are prepared by grafting epoxyphosphorylsuccinic acid on the surface of amino silicon dioxide; the modified polyurethane is prepared by reacting hydroxy polyphenyl ether, hydroxy fluorosilicone oil and toluene diisocyanate to prepare a modified polyurethane prepolymer, and then reacting with a fluorine-containing chain extender to extend the chain.

2. The high-strength flame-retardant battery pack shell according to claim 1, characterized in that: The epoxyphosphorylsuccinic acid is prepared by the reaction of diphenylphosphine oxide, maleic acid and long-chain hydroxydiphenyl sulfide; the long-chain hydroxydiphenyl sulfide is prepared by the reaction of 4,4'-dihydroxydiphenyl sulfide and epichlorohydrin.

3. The high-strength flame-retardant battery pack shell according to claim 1, characterized in that: The fluorine-containing chain extender is prepared by the reaction of cyanuric chloride, octafluoropentanol and ethanolamine.

4. A method for preparing a high-strength flame-retardant battery pack shell as claimed in claim 1, characterized in that: The specific steps include: S1. Under a nitrogen atmosphere, 4,4′-dihydroxydiphenyl sulfide and epichlorohydrin are mixed in a mass ratio of 1:0.8~1.2, stirred and dissolved, and tetra-n-butylammonium bromide of 0.2~0.4 times the mass of epichlorohydrin is added, the temperature is raised to 70~90°C, the reaction is carried out for 20~40 minutes, the epichlorohydrin is recovered under reduced pressure, and then toluene of the same mass as 4,4′-dihydroxydiphenyl sulfide and phosphoinosuccinic acid of 1.6~1.8 times the mass of 4,4′-dihydroxydiphenyl sulfide are added, the reaction is continued for 4~6 hours, the mixture is filtered and washed with deionized water for 3~5 times, and distilled under reduced pressure to obtain epoxyphosphoinosuccinic acid; S2. Under a nitrogen atmosphere, epoxyphosphorylsuccinic acid, aminosilica and dichloroethane were mixed in a mass ratio of 5:2~3:20~30, stirred evenly, and triethylamine in an amount of 0.4~0.6 times the mass of epoxyphosphorylsuccinic acid was added, the temperature was raised to 80~90°C, the reaction was stirred at 400~800rpm for 22~26h, centrifuged and washed with dichloroethane 3~5 times to obtain flame retardant particles; S3. Mix hydroxy polyphenylene ether and hydroxy fluorosilicone oil in a mass ratio of 1:0.4-0.8, heat to 100-110°C, vacuum dehydrate to a moisture content of 0.02-0.05%, cool to 40-50°C, add dibutyltin dilaurate in an amount of 0.01-0.02 times the mass of hydroxy polyphenylene ether and toluene diisocyanate in an amount of 1.4-1.8 times the mass of hydroxy polyphenylene ether, heat to 75-85°C, and keep warm for 4-6 hours to obtain a polyurethane prepolymer; S4. After the polyurethane prepolymer is stirred for 20 to 40 minutes, vacuum degassing is performed, and a fluorine-containing chain extender of 0.12 to 0.14 times the mass of the polyurethane prepolymer is added, and after stirring at 600 to 800 rpm for 20 to 40 minutes, vacuum degassing is performed, and room temperature vulcanization is performed for 6 to 7 days to obtain a modified polyurethane; S5. The modified polyurethane, flame retardant particles and tetrahydrofuran were mixed in a mass ratio of 5-8:0.2-0.6:100, stirred at 1000-2000 rpm for 18-24 h, and then dried in a vacuum drying oven at 50-60 ° C to obtain a composite polyurethane; S6. Electric-cut the glass fiber, stack the cut glass fiber cloth, staple the edges with a stapler, clamp and send it into the spray room, place the metal part in the mold sprayed with release agent, mix the composite polyurethane and water in a mass ratio of 20~40:1~3 in a foaming machine, spray it on the glass fiber cloth with a spray gun, heat the mold to 175~185℃, place the sprayed glass fiber on the metal part, close the mold, pressurize it to 100~120MPa, remove the mold after hot pressing for 5~7min, and perform post-processing to obtain a high-strength flame-retardant battery pack shell.

5. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S1., the preparation method of phosphoinosuccinic acid is as follows: under a nitrogen atmosphere, diphenylphosphine oxide, maleic acid and propionic acid are mixed in a mass ratio of 3.8~4.2:3:40, the temperature is raised to 80~90°C, the reaction is stirred at 400~800rpm for 18~22h, and the mixture is rotary evaporated and successively treated with ethanol and acetic acid 3~5 times, and then dissolved in a potassium hydroxide solution with a mass fraction of 4~8%, and 1~2mol / l hydrochloric acid is added for precipitation, and finally washed with ethanol 3~5 times, and dried in a vacuum drying oven at 60°C to obtain phosphoinosuccinic acid.

6. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S2., the preparation method of amino silica is: ethanol and ammonia water with a mass fraction of 10-30% are mixed in a mass ratio of 20:0.8-1.2, the temperature is raised to 40-42°C, and ammonia water is added with an equal mass of ethyl orthosilicate, and the reaction is stirred at 200-600rpm for 10-12h, and then KH-550 with a mass of 0.12-0.16 times that of ammonia water is added. After continuing the reaction for 5-6h, the temperature is raised to 78-82°C, refluxed for 2-3h, centrifuged, washed with ethanol and dichloromethane for 3-5 times in sequence, and dried to obtain amino silica.

7. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S3., the preparation method of hydroxypolyphenylene ether is: 2,6-dimethylphenol, 2,2',4,4'-tetramethylbisphenol A and toluene are mixed in a mass ratio of 1:10~12:50, stirred and dissolved, and then 0.1~0.2 times the mass of 2,6-dimethylphenol copper chloride and 0.25~0.35 times the mass of 2,6-dimethylphenol-dimethylaminopyridine are added, the temperature is raised to 40~42°C, oxygen is continuously passed at a rate of 4~6ml / min, and after reacting for 3~6h, the reaction is quenched with acetic acid to terminate the reaction, and then separated and filtered with saturated brine, dried with anhydrous sodium sulfate, distilled under reduced pressure, precipitated with methanol and filtered, and then washed with methanol 3~5 times, and vacuum dried at 80°C to obtain hydroxypolyphenylene ether.

8. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S4., the preparation method of the fluorine-containing chain extender is: cyanuric chloride, acetone and deionized water are mixed in a mass ratio of 1:3-6:3, and at the same time, an acetone solution of 1.2-1.4 times the mass of cyanuric chloride with a mass fraction of 1-4% octafluoropentanol and a sodium hydroxide solution of 2.6-2.9 times the mass of cyanuric chloride with a mass fraction of 8-10% are added dropwise at a rate of 1-3 ml / min, react at room temperature for 3-6 hours, heat to 42-48°C, add cyanuric chloride with a mass fraction of 0. 3~0.4 times the mass of ethanolamine and 2.6~2.9 times the mass of cyanuric chloride with a mass fraction of 8~10% sodium hydroxide solution, continue to react for 3~5 hours, heat to 92~98°C, add 0.3~0.4 times the mass of ethanolamine and 2.6~2.9 times the mass of cyanuric chloride with a mass fraction of 8~10% sodium hydroxide solution again, continue to react for 6~8 hours, cool to room temperature, filter and wash with acetone and deionized water 3~5 times, and vacuum dry to obtain a fluorine-containing chain extender.

9. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S6., the spray gun pressure is 130-150 MPa, and the spraying time is 2-4 seconds; the metal part is an aluminum metal part or an iron metal part; and the release agent is a mixture of 36-40% by mass of polysiloxane and 60-64% by mass of water.

10. The method for preparing a high-strength flame-retardant battery pack shell according to claim 4, characterized in that: In the above step S6., the post-processing process is as follows: opening holes, washing with tap water, air drying, air tightness testing, and finally packaging.