A flame-retardant and insulating powder coating for new energy vehicles and its preparation method

Abstract

The present invention discloses a flame-retardant and insulating powder coating for new energy vehicles and a preparation method thereof, belonging to the technical field of coatings; the flame-retardant and insulating powder coating for new energy vehicles of the present invention, by weight, the raw material components include 380-384 parts by mass of epoxy resin, 56-58 parts by mass of toughening agent, 5-10 parts by mass of modified flame-retardant filler, 100-101 parts by mass of composite curing agent, 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator; the toughening agent is obtained by reacting isophorone diisocyanate trimer, 4-bromophenol, and N-p-coumaroyltyramine; the modified flame-retardant filler is obtained by first coating hexagonal boron nitride with polydopamine and then modifying it with a silane coupling agent; the silane coupling agent is obtained by combining 4-benzonitrile oxybutyltrimethoxysilane and a mercapto silane coupling agent; the composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and an amino-mercapto functional organic polysiloxane.

Description

Technical Field

[0001] The invention relates to a flame retardant insulating powder coating for new energy vehicles and a preparation method thereof. Background Art

[0002] As global awareness of environmental protection increases, the release of volatile organic compounds (VOCs) has become an environmental issue of widespread concern. In this context, powder coatings, as an environmentally friendly coating, are favored because they do not release volatile organic compounds during use. Powder coatings are a 100% solid powder coating composed of resins, curing agents, and various pigment fillers that are melt-mixed. They are often used as surface coatings and decorative materials and are widely used in construction, industry, automobiles, home appliances and other fields. Compared with traditional solvent and liquid coatings, powder coatings not only meet the "4E" principles of contemporary environmental protection (environmental protection, high efficiency, ecology, and economy), but their use is also increasing year by year.

[0003] In order to meet the market demand for high-performance coatings, the research and development of powder coatings is moving towards improving their physical properties. Despite this, most of the current research on the functionalization of coatings is focused on liquid coatings, and there is relatively little research on powder coatings, especially flame-retardant insulating powder coatings for new energy vehicles. Epoxy resin has become one of the widely used resins in powder coatings due to its good corrosion resistance, high mechanical strength and excellent insulation. However, due to the influence of the high-density three-dimensional cross-linked network formed by epoxy resin during the curing process, cracks and holes will inevitably appear, resulting in physical defects on the coating surface. These problems limit the use of powder coatings in more demanding applications, such as coatings with good toughness, impact resistance, flame retardancy and thermal conductivity required in the field of new energy vehicles.

[0004] Therefore, the applicant prepared a flame retardant insulating powder coating for new energy vehicles. Summary of the invention

[0005] The purpose of the present invention is to provide a flame retardant insulating powder coating for new energy vehicles and a preparation method thereof, so as to solve the technical problems mentioned in the above background technology.

[0006] The technical solution for achieving the purpose of the present invention is:

[0007] The first aspect of the present invention provides a flame retardant insulating powder coating for new energy vehicles. The raw material components include, by weight: 380-384 parts by weight of epoxy resin, 56-58 parts by weight of toughening agent, 5-10 parts by weight of modified flame retardant filler, 100-101 parts by weight of composite curing agent, 5 parts by weight of leveling agent, 1 part by weight of benzoin, and 0.7 parts by weight of accelerator.

[0008] Further, the toughening agent is obtained by reacting isophorone diisocyanate trimer, 4-bromophenol, and N-p-coumaroyltyramine.

[0009] Further, the modified flame retardant filler is obtained by first coating hexagonal boron nitride with polydopamine and then modifying it with a silane coupling agent.

[0010] Further, the silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and a mercapto silane coupling agent.

[0011] Further, the composite curing agent includes 4,4-diaminodiphenylmethane and an amino-mercapto functional organopolysiloxane.

[0012] The second aspect of the present invention provides a preparation method of a flame retardant and insulating powder coating for new energy vehicles as described in the first aspect. The preparation steps include:

[0013] (1) Add 5.6 - 5.8 parts by mass of magnesium powder and 50 - 60 parts by mass of anhydrous ether. While stirring, slowly add 5 parts by mass of the toughening agent and 0.24 - 0.26 parts by mass of iodine. Then heat to a slightly boiling state. While in the slightly boiling state, dropwise add a mixture of 101 - 123 parts by mass of the toughening agent and ether. Finish dropping within 60 min, and then reflux for 2.5 - 3.5 h. Among them, the mass of the toughening agent in the mixture of the toughening agent and ether is 51 - 53 parts by mass, and the mass of ether is 50 - 70 parts by mass. After cooling to room temperature, add 45 - 70 parts by mass of an ether dispersion of the modified flame retardant filler. After adding it within 60 min, reflux and react for 4.5 - 5.5 h and then cool to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of the modified flame retardant filler is 5 - 10 parts by mass, and the mass of ether is 40 - 60 parts by mass. Then add 40 - 60 parts by mass of methanol and stir at room temperature for 50 - 70 min, filter, and dry overnight at 70 °C under nitrogen protection to obtain a premix;

[0014] (2) Mix 100 - 101 parts by mass of the composite curing agent and a hydrochloric acid solution with a mass fraction of 36% at a mass ratio of 1:1.8 - 2.2. Then filter and dry. Next, add it to dichloromethane 5 - 15 times the mass of the composite curing agent and stir and mix for 30 - 60 min. Then add the premix obtained in step (1) and continue to stir and react for 2 - 4 h. Rotate and evaporate dichloromethane at 40 - 50 °C to obtain a secondary mixture;

[0015] (3) Manually mix 380 - 384 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of a leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of an accelerator evenly. Then use a twin-screw extruder with a rotation speed of 35 rpm to melt and mix and extrude sheet materials. After the sheet materials are cooled, grind them in a high-speed grinder and pass through a 160-mesh sieve to obtain a flame retardant and insulating powder coating for new energy vehicles.

[0016] Further, the preparation steps of the toughening agent are as follows: Dissolve 16.4 to 16.44 parts by mass of N-p-coumaroyltyramine in 70 to 74 parts by mass of 1,4-dioxane, and then dropwise add 11 to 11.2 parts by mass of isophorone diisocyanate trimer at a rate of 1 to 3 drops per second. After heating to 78 to 82 °C and stirring for reaction for 3.5 to 4.5 h, add a mixed solution of 77.8 to 81.9 parts by mass of 4-bromophenol, wherein 7.8 to 7.9 parts by mass of 4-bromophenol is dissolved in 70 to 74 parts by mass of 1,4-dioxane, continue stirring for reaction for 3.5 to 4.5 h, and after the reaction is completed, remove the solvent 1,4-dioxane by rotary evaporation at 68 to 72 °C to obtain the toughening agent.

[0017] Further, the preparation steps of the modified flame retardant filler are as follows: Add 2.2 to 2.6 parts by mass of dopamine hydrochloride and 5 to 7 parts by mass of hexagonal boron nitride to 1000 parts by mass of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 25 to 35 min, stir at room temperature for reaction for 23 to 25 h. After the reaction is completed, perform vacuum filtration, wash the precipitate with deionized water until the filtrate is colorless, and then dry at 60 °C for 23 to 25 h to obtain hexagonal boron nitride encapsulated with polydopamine; Add 9 to 11 parts by mass of hexagonal boron nitride encapsulated with polydopamine to an ethanol aqueous solution with a volume ratio of 49:1, then add 0.4 to 0.6 parts by mass of a silane coupling agent, ultrasonicate for 15 to 25 min, stir at 78 to 82 °C at 500 rpm for 5.5 to 6.5 h, then centrifuge at 6000 rpm for 10 min, wash with ethanol multiple times, and vacuum dry at 60 °C for 23 to 25 h to obtain the modified flame retardant filler.

[0018] Further, the silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and a mercapto silane coupling agent in a mass ratio of 1:0.8 to 1.2; among them, the mercapto silane coupling agent is preferably silane coupling agent KH580.

[0019] Further, the composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and an amino-mercapto functional organopolysiloxane in a mass ratio of 1:0.4 to 0.6.

[0020] Adopting the above technical solutions, the present invention has the following beneficial effects:

[0021] (1)The flame-retardant and insulating powder coating for new energy vehicles of the present invention, by weight, the raw material components include 380-384 parts by mass of epoxy resin, 56-58 parts by mass of toughening agent, 5-10 parts by mass of modified flame-retardant filler, 100-101 parts by mass of composite curing agent, 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator; by adding a modified flame-retardant filler, toughening agent, and composite curing agent to the flame-retardant and insulating powder coating for new energy vehicles, the flame-retardant and insulating powder coating for new energy vehicles has good toughness, impact resistance, and flame retardancy.

[0022] (2)The present invention adds a modified flame-retardant filler to the flame-retardant and insulating powder coating for new energy vehicles. Among them, the modified flame-retardant filler is obtained by first coating hexagonal boron nitride with polydopamine and then modifying it with a silane coupling agent; the silane coupling agent is obtained by combining 4-benzonitrile oxybutyltrimethoxysilane and a mercapto silane coupling agent; hexagonal boron nitride exhibits excellent properties in terms of heat conduction, electrical insulation, antioxidant, and radiation shielding. Hexagonal boron nitride can not only fill the microcracks caused by resin curing to improve the denseness of the coating, but also its layered structure can form a "labyrinth effect" in the coating, extending the penetration path of corrosive media or combustion gases, endowing the coating with flame retardancy and anti-corrosion properties; however, the interaction force between B atoms and N atoms in adjacent layers is called the lip-lip interaction, resulting in poor dispersion of hexagonal boron nitride agglomerates in the coating, greatly reducing the apparent performance and mechanical properties of the coating; using a modified flame-retardant filler obtained by first coating hexagonal boron nitride with polydopamine and then modifying it with a silane coupling agent can effectively improve the dispersion and interfacial compatibility of hexagonal boron nitride in the coating, thereby ensuring and enhancing the apparent performance and mechanical properties of the coating.

[0023] (3)The toughening agent of the present invention is obtained by reacting isophorone diisocyanate trimer, 4-bromophenol, and N-p-coumaroyltyramine; the hydrogen bond in the molecular structure of the toughening agent serves as a sacrificial bond to increase the toughness of the resin, while the high-rigidity structure of the benzene ring and six-membered ring and the rigid conjugated structure of the benzene ring olefin enhance the mechanical properties to a certain extent; moreover, the rigid conjugated structure of the benzene ring olefin in the molecular structure of the toughening agent promotes the formation of char residue and endows the material with higher thermal stability; in addition, the toughening agent introduces a nitrogen-containing structure and a rigid conjugated structure into the epoxy resin matrix. On the one hand, it can generate incombustible gases through thermal decomposition, reduce toxic and harmful smoke, and significantly improve its fire safety; on the other hand, the toughening agent reacts with other raw material components in the powder coating to form a stable cross-linked network, forming a dense carbon layer after combustion, which can effectively prevent the further combustion of the resin matrix as a protective layer for the resin matrix, enhancing the flame retardancy of the flame-retardant and insulating powder coating for new energy vehicles.

[0024] (4) The composite curing agent of the present invention is obtained by combining 4,4-diaminodiphenylmethane and amino-thiol-functionalized organopolysiloxane; wherein, the introduction of amino-thiol-functionalized organopolysiloxane as an epoxy resin curing agent introduces a flexible organosilicon molecular chain into the coating, and as the second phase containing a flexible structure, it effectively improves the toughness of the epoxy resin cured material; and during the combustion process, the amino-thiol-functionalized organopolysiloxane undergoes self-crosslinking upon heating to form a continuous and dense silica layer, preventing the substrate from catching fire and burning, thereby reducing the heat loss inside the polymer, while the hexagonal boron nitride in the modified flame retardant filler in the coating forms a physical barrier to heat and volatile gases in the condensed state, namely the so-called "zigzag path" effect, which can cooperate with the amino-thiol-functionalized organopolysiloxane to provide a good barrier, limit the transmission of external heat and flammable gases, and slow down the diffusion of volatile combustibles, further enhancing the flame retardant performance of the flame retardant and insulating powder coating for new energy vehicles.

[0025] (5) In the present invention, the toughening agent and the modified flame retardant filler are first subjected to a premixing reaction to obtain a premix, then the premix is mixed with the composite curing agent, and finally, it is melt-kneaded and extruded with epoxy resin, a leveling agent, benzoin, and a promoter to obtain a flame retardant and insulating powder coating for new energy vehicles. The bromobenzene on the toughening agent reacts with the benzonitrile on the modified flame retardant filler to form a benzophenone imine derivative. Then, when the premix is mixed with the composite curing agent, the diphenyl imine in the premix reacts with the primary amine to block and protect the primary amine, which can effectively slow down the curing rate and avoid a large number of pinholes appearing when it is used for thick film coating, that is, the film thickness ≥ 90 μm, which affects the appearance performance of the coating; at the same time, the thiol groups in the premix react with the thiol groups in the composite curing agent to crosslink and form dynamic disulfide bonds, endowing the flame retardant and insulating powder coating for new energy vehicles with good self-healing performance. Specific Embodiments

[0026] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with specific embodiments.

[0027] The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

[0028] Some raw materials of the examples and comparative examples of the present invention are as follows:

[0029] Thiol silane coupling agent: Silane coupling agent KH580.

[0030] The epoxy resin used is E51 type epoxy resin, with an average epoxy value of 0.51 and an average hydroxyl value of 0.046.

[0031] The leveling agent used is leveling agent GLP588.

[0032] The accelerator used is 2-methylimidazole.

[0033] The preparation steps of 4-benzonitrileoxybutyltrimethoxysilane are as follows: Add 4-hydroxybenzonitrile, potassium hydroxide and tetrahydrofuran into a 1-L wide-mouth bottle. After the temperature drops to 20 °C, add 4-bromo-1-butene. Among them, the molar ratio of 4-hydroxybenzonitrile, 4-bromo-1-butene to potassium hydroxide is 1:2:3, and the mass ratio of 4-hydroxybenzonitrile to tetrahydrofuran is 25:555. Stir overnight at room temperature, rotary evaporate tetrahydrofuran and excessive 4-bromo-1-butene, then add dichloromethane. Extract the organic phase successively with deionized water and saturated brine. Dry the organic phase with anhydrous sodium sulfate, remove the vast majority of the solvent with a rotary evaporator, mix the residue, and finally purify it by column chromatography with ethyl acetate / petroleum ether = 3% to obtain 4-(allyloxy)benzonitrile; Add 4-(allyloxy)benzonitrile, trimethoxysilane, the catalyst chloroplatinic acid and 1,4-dioxane into a single-necked flask in turn. Among them, the molar ratio of 4-(allyloxy)benzonitrile, trimethoxysilane to the catalyst chloroplatinic acid is 1:2:0.04, and the mass ratio of 4-(allyloxy)benzonitrile to 1,4-dioxane is 10:258; Stir the reaction solution overnight at 115 °C under nitrogen protection. After the reaction solution is cooled to room temperature, rotary evaporate and mix the sample, and finally purify it by column chromatography with ethyl acetate / petroleum ether = 3% to obtain 4-benzonitrileoxybutyltrimethoxysilane.

[0034] The preparation steps of amino-thiol functionalized organopolysiloxane are as follows: Add 31.5 parts by mass of silanol-terminated polydimethylsiloxane Tech-2170 produced by Shanghai Tiger Polymer Technology Co., Ltd. into a reaction vessel, then add 4.9 parts by mass of aminopropylmethyldimethoxysilane and 4.1 parts by mass of mercaptopropylmethyldiethoxysilane, then add 0.7 parts by mass of barium hydroxide and 0.26 parts by mass of sodium orthophosphate. Then heat to 80 °C and keep warm for 3 h, then reduce the pressure to 200 mbar and place for 1 - 3 h. Then add 10.1 parts by mass of linear aliphatic tridecanol and maintain the reaction at 80 °C and atmospheric pressure for 2 h to obtain amino-thiol functionalized organopolysiloxane.

[0035] (Example 1)

[0036] A preparation method of a flame-retardant insulating powder coating for new energy vehicles, the preparation steps include:

[0037] (1) In 5.6 parts by mass of magnesium powder and 50 parts by mass of anhydrous ether, 5 parts by mass of toughening agent and 0.24 parts by mass of iodine are slowly added under stirring. Subsequently, it is heated to a slightly boiling state, and a mixed solution of 101 parts by mass of toughening agent and ether is added dropwise under the slightly boiling state. The addition is completed within 60 min, and then refluxed for 2.5 h. Among them, the mass of the toughening agent in the mixed solution of toughening agent and ether is 51 parts by mass, and the mass of ether is 50 parts by mass; after cooling to room temperature, 45 parts by mass of an ether dispersion of modified flame retardant filler is added. After adding it within 60 min, it is refluxed for 4.5 h and then cooled to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of modified flame retardant filler is 5 parts by mass, and the mass of ether is 40 parts by mass; subsequently, 40 parts by mass of methanol is added and stirred at room temperature for 50 min, filtered, and dried overnight at 70 °C under nitrogen protection to obtain a premix;

[0038] (2) 100 parts by mass of composite curing agent and a hydrochloric acid solution with a mass fraction of 36% are mixed at a mass ratio of 1:1.8, then filtered and dried. Then, it is added to 5 times the mass of dichloromethane of the composite curing agent and stirred and mixed for 30 min. Subsequently, the premix obtained in step (1) is added and the stirring reaction continues for 2 h. Dichloromethane is removed by rotary evaporation at 40 °C to obtain a secondary mixture;

[0039] (3) 380 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator are manually mixed evenly, and then extruded into sheet materials by melt mixing using a twin-screw extruder with a rotational speed of 35 rpm. After the sheet materials are cooled, they are ground in a high-speed grinder and passed through a 160-mesh sieve to obtain a flame-retardant insulating powder coating for new energy vehicles; the temperature setting of the extruder: zone I 85 °C, zone II 100 °C.

[0040] Among them, the preparation steps of the toughening agent are as follows: 16.4 parts by mass of N-p-coumaroyltyramine is dissolved in 70 parts by mass of 1,4-dioxane, and then 11 parts by mass of isophorone diisocyanate trimer is added dropwise at 1 drop / s. After heating to 78 °C and stirring for 3.5 h, a mixed solution of 77.8 parts by mass of 4-bromophenol is added. Among them, 7.8 parts by mass of 4-bromophenol is dissolved in 70 parts by mass of 1,4-dioxane, and the stirring reaction continues for 3.5 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 68 °C to obtain the toughening agent.

[0041] The preparation steps of the modified flame retardant filler are as follows: Add 2.2 parts by mass of dopamine hydrochloride and 5 parts by mass of hexagonal boron nitride into 1000 parts by mass of tris(hydroxymethyl)aminomethane-hydrochloride buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 25 min, stir and react at room temperature for 23 h. After the reaction, perform vacuum filtration. Wash the precipitate with deionized water until the filtrate is colorless, and then dry it at 60 °C for 23 h to obtain hexagonal boron nitride encapsulated with polydopamine. Add 9 parts by mass of hexagonal boron nitride encapsulated with polydopamine into an ethanol aqueous solution with a volume ratio of 49:1, and then add 0.4 parts by mass of silane coupling agent. Ultrasonic for 15 min, stir at 78 °C at 500 rpm for 5.5 h, then centrifuge at 6000 rpm for 10 min, wash with ethanol 3 times, and dry under vacuum at 60 °C for 23 h to obtain the modified flame retardant filler.

[0042] The silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:0.8.

[0043] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functionalized organopolysiloxane in a mass ratio of 1:0.4.

[0044] (Example 2)

[0045] A preparation method of a flame retardant and insulating powder coating for new energy vehicles, the preparation steps include:

[0046] (1) Slowly add 5 parts by mass of toughening agent and 0.25 parts by mass of iodine to 5.7 parts by mass of magnesium powder and 55 parts by mass of anhydrous ether under stirring, then heat to a slightly boiling state, and dropwise add a mixed solution of 112 parts by mass of toughening agent and ether within 60 min, and finish dropping within 60 min, then reflux for 3 h. Among them, the mass of the toughening agent in the mixed solution of toughening agent and ether is 52 parts by mass, and the mass of ether is 60 parts by mass. After cooling to room temperature, add 57.5 parts by mass of an ether dispersion of the modified flame retardant filler, and after adding it within 60 min, reflux and react for 5 h and then cool to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of the modified flame retardant filler is 7.5 parts by mass, and the mass of ether is 50 parts by mass. Then add 50 parts by mass of methanol and stir at room temperature for 60 min, filter, and dry overnight at 70 °C under nitrogen protection to obtain a premix;

[0047] (2) Mix 100.5 parts by mass of the composite curing agent and a hydrochloric acid solution with a mass fraction of 36% in a mass ratio of 1:2, then filter and dry, then add it to dichloromethane 10 times the mass of the composite curing agent and stir and mix for 45 min, then add the premix obtained in step (1) and continue to stir and react for 3 h, and remove dichloromethane by rotary evaporation at 45 °C to obtain a secondary mixture;

[0048] (3) Manually mix 382 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator evenly, and then use a twin-screw extruder with a rotation speed of 35 rpm to extrude sheet materials through melt mixing. After the sheet materials are cooled, they are ground in a high-speed grinder and sieved through a 160-mesh sieve to obtain a flame-retardant and insulating powder coating for new energy vehicles; the temperature of the extruder is set as follows: zone I 85 °C, zone II 100 °C.

[0049] Among them, the preparation steps of the toughening agent are as follows: Dissolve 16.42 parts by mass of N-p-coumaroyltyramine in 72 parts by mass of 1,4-dioxane, and then drop 11.1 parts by mass of isophorone diisocyanate trimer at a rate of 2 drops per second. After heating to 80 °C and stirring for 4 h, add a mixed solution of 79.85 parts by mass of 4-bromophenol, among which 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and continue to stir and react for 4 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 70 °C to obtain the toughening agent.

[0050] The preparation steps of the modified flame-retardant filler are as follows: Add 2.4 parts by mass of hydrochloric acid dopamine and 6 parts by mass of hexagonal boron nitride to 1000 parts by mass of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5, ultrasonically treat for 30 min, and then stir and react at room temperature for 24 h. After the reaction is completed, vacuum filter, wash the precipitate with deionized water until the filtrate is colorless, and then dry at 60 °C for 24 h to obtain hexagonal boron nitride coated with polydopamine; add 10 parts by mass of hexagonal boron nitride coated with polydopamine to an ethanol aqueous solution with a volume ratio of 49:1, add 0.5 part by mass of silane coupling agent, ultrasonically treat for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at 6000 rpm at high speed for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame-retardant filler.

[0051] The silane coupling agent is obtained by combining 4-benzonitrile oxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:1.

[0052] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functionalized organopolysiloxane in a mass ratio of 1:0.5.

[0053] (Example 3)

[0054] A preparation method of a flame-retardant and insulating powder coating for new energy vehicles, the preparation steps include:

[0055] (1) In 5.8 parts by mass of magnesium powder and 60 parts by mass of anhydrous ether, 5 parts by mass of toughening agent and 0.26 parts by mass of iodine are slowly added under stirring. Subsequently, it is heated to a slightly boiling state, and a mixed solution of 123 parts by mass of toughening agent and ether is added dropwise under the slightly boiling state. The addition is completed within 60 min, and then refluxed for 3.5 h. Among them, the mass of the toughening agent in the mixed solution of toughening agent and ether is 53 parts by mass, and the mass of ether is 70 parts by mass; after cooling to room temperature, 70 parts by mass of an ether dispersion of modified flame retardant filler is added. After adding it within 60 min, the mixture is refluxed and reacted for 5.5 h and then cooled to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of modified flame retardant filler is 10 parts by mass, and the mass of ether is 60 parts by mass; subsequently, 60 parts by mass of methanol is added and stirred at room temperature for 70 min, filtered, and dried overnight at 70 °C under nitrogen protection to obtain a premix;

[0056] (2) 101 parts by mass of a composite curing agent and a hydrochloric acid solution with a mass fraction of 36% are mixed at a mass ratio of 1:2.2, then filtered and dried. Then, it is added to 15 times the mass of the composite curing agent of dichloromethane and stirred and mixed for 60 min. Subsequently, the premix obtained in step (1) is added and the reaction is continued to stir for 4 h. Dichloromethane is removed by rotary evaporation at 50 °C to obtain a secondary mixture;

[0057] (3) 384 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator are manually mixed evenly, and then extruded into sheet materials by melt mixing using a twin-screw extruder with a rotation speed of 35 rpm. After the sheet materials are cooled, they are ground in a high-speed grinder and passed through a 160-mesh sieve to obtain a flame retardant and insulating powder coating for new energy vehicles; the temperature setting of the extruder: zone I 85 °C, zone II 100 °C.

[0058] Among them, the preparation steps of the toughening agent are as follows: 16.44 parts by mass of N-p-coumaroyltyramine is dissolved in 74 parts by mass of 1,4-dioxane, and then 11.2 parts by mass of isophorone diisocyanate trimer is added dropwise at 3 s / drop. After heating to 82 °C and stirring and reacting for 4.5 h, a mixed solution of 81.9 parts by mass of 4-bromophenol is added. Among them, 7.9 parts by mass of 4-bromophenol is dissolved in 74 parts by mass of 1,4-dioxane, and the reaction is continued to stir for 4.5 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 72 °C to obtain the toughening agent.

[0059] The preparation steps of the modified flame retardant filler are as follows: Add 2.6 parts by mass of dopamine hydrochloride and 7 parts by mass of hexagonal boron nitride into 1000 parts by mass of tris(hydroxymethyl)aminomethane-hydrochloride buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 35 min, stir and react at room temperature for 25 h. After the reaction, perform vacuum filtration. Wash the precipitate with deionized water until the filtrate is colorless, and then dry it at 60 °C for 25 h to obtain hexagonal boron nitride wrapped with polydopamine. Add 11 parts by mass of hexagonal boron nitride wrapped with polydopamine into an ethanol-water solution with a volume ratio of 49:1, and then add 0.6 parts by mass of silane coupling agent. Ultrasonic for 25 min, stir at 82 °C at 500 rpm for 6.5 h, then centrifuge at 6000 rpm for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 25 h to obtain the modified flame retardant filler.

[0060] The silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:1.2.

[0061] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functionalized organopolysiloxane in a mass ratio of 1:0.6.

[0062] (Comparative Example 1)

[0063] A preparation method of a flame retardant and insulating powder coating for new energy vehicles, the preparation steps include:

[0064] Manually mix 382 parts by mass of epoxy resin, 7.5 parts by mass of modified flame retardant filler, 100.5 parts by mass of composite curing agent, 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator evenly, and then use a twin-screw extruder with a rotation speed of 35 rpm to extrude sheet materials through melt mixing. After the sheet materials are cooled, grind them in a high-speed grinder and pass through a 160-mesh sieve to obtain a flame retardant and insulating powder coating for new energy vehicles; the temperature setting of the extruder: Zone I is 85 °C, and Zone II is 100 °C.

[0065] The preparation steps of the modified flame retardant filler are as follows: Add 2.4 parts by mass of dopamine hydrochloride and 6 parts by mass of hexagonal boron nitride into 1000 parts by mass of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 30 min, stir and react at room temperature for 24 h. After the reaction, perform vacuum filtration. Wash the precipitate with deionized water until the filtrate is colorless, and then dry it at 60 °C for 24 h to obtain hexagonal boron nitride wrapped with polydopamine. Add 10 parts by mass of hexagonal boron nitride wrapped with polydopamine into an ethanol-water solution with a volume ratio of 49:1, and then add 0.5 parts by mass of silane coupling agent. Ultrasonic for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at a high speed of 6000 rpm for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame retardant filler.

[0066] The silane coupling agent is obtained by combining 4-cyanophenoxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:1.

[0067] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functionalized organopolysiloxane in a mass ratio of 1:0.5.

[0068] (Comparative Example 2)

[0069] A preparation method of a flame retardant and insulating powder coating for new energy vehicles, the preparation steps include:

[0070] (1) Slowly add 5 parts by mass of toughening agent and 0.25 parts by mass of iodine to 5.7 parts by mass of magnesium powder and 55 parts by mass of anhydrous ether under stirring, then heat to a slightly boiling state, and dropwise add a mixed solution of 112 parts by mass of toughening agent and ether within 60 min. Finish dropping within 60 min, and then reflux for 3 h. Among them, the mass of the toughening agent in the mixed solution of toughening agent and ether is 52 parts by mass, and the mass of ether is 60 parts by mass. After cooling to room temperature, add 57.5 parts by mass of an ether dispersion of the modified flame retardant filler. After adding it within 60 min, reflux and react for 5 h and then cool to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of the modified flame retardant filler is 7.5 parts by mass, and the mass of ether is 50 parts by mass. Then add 50 parts by mass of methanol and stir at room temperature for 60 min, filter, and dry overnight at 70 °C under nitrogen protection to obtain a premix;

[0071] (2) Mix 100.5 parts by mass of the composite curing agent and a hydrochloric acid solution with a mass fraction of 36% in a mass ratio of 1:2, then filter and dry. Then add it to dichloromethane 10 times the mass of the composite curing agent and stir and mix for 45 min. Then add the premix obtained in step (1) and continue to stir and react for 3 h. Rotate and evaporate dichloromethane at 45 °C to obtain a secondary mixture;

[0072] (3) Manually mix 382 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator evenly, and then use a twin-screw extruder with a rotation speed of 35 rpm to extrude sheet materials through melt mixing. After the sheet materials are cooled, they are ground in a high-speed grinder and sieved through a 160-mesh sieve to obtain a flame-retardant insulating powder coating for new energy vehicles; the temperature settings of the extruder are: zone I 85 °C, zone II 100 °C.

[0073] Among them, the preparation steps of the toughening agent are as follows: Dissolve 16.42 parts by mass of N-p-coumaroyltyramine in 72 parts by mass of 1,4-dioxane, and then drop 11.1 parts by mass of isophorone diisocyanate trimer at a rate of 2 drops / s. After heating to 80 °C and stirring for 4 h, add a mixed solution of 79.85 parts by mass of 4-bromophenol, among which 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and continue to stir and react for 4 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 70 °C to obtain the toughening agent.

[0074] The preparation steps of the modified flame-retardant filler are as follows: Add 2.4 parts by mass of hydrochloric acid dopamine and 6 parts by mass of hexagonal boron nitride to 1000 parts by mass of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5, ultrasonically treat for 30 min, and then stir and react at room temperature for 24 h. After the reaction is completed, vacuum filter, wash the precipitate with deionized water until the filtrate is colorless, and then dry at 60 °C for 24 h to obtain hexagonal boron nitride wrapped with polydopamine; add 10 parts by mass of hexagonal boron nitride wrapped with polydopamine to an ethanol aqueous solution with a volume ratio of 49:1, add 0.5 part by mass of silane coupling agent, ultrasonically treat for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at 6000 rpm for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame-retardant filler.

[0075] The silane coupling agent uses 4-benzonitrileoxybutyltrimethoxysilane.

[0076] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto-functional organopolysiloxane in a mass ratio of 1:0.5.

[0077] (Comparative Example 3)

[0078] A preparation method of a flame-retardant insulating powder coating for new energy vehicles, the preparation steps include:

[0079] (1) In 5.7 parts by mass of magnesium powder and 55 parts by mass of anhydrous ether, 5 parts by mass of toughening agent and 0.25 parts by mass of iodine are slowly added under stirring. Subsequently, it is heated to a slightly boiling state, and a mixed solution of 112 parts by mass of toughening agent and ether is added dropwise under the slightly boiling state. The addition is completed within 60 min, and then it is refluxed for 3 h. Among them, the mass of the toughening agent in the mixed solution of toughening agent and ether is 52 parts by mass, and the mass of ether is 60 parts by mass; after cooling to room temperature, an ether dispersion of 57.5 parts by mass of modified flame retardant filler is added. After adding it within 60 min, it is refluxed for 5 h and then cooled to room temperature. Among them, the mass of the modified flame retardant filler in the ether dispersion of modified flame retardant filler is 7.5 parts by mass, and the mass of ether is 50 parts by mass; then 50 parts by mass of methanol is added and stirred at room temperature for 60 min, filtered, and dried overnight at 70 °C under nitrogen protection to obtain a premix;

[0080] (2) 100.5 parts by mass of composite curing agent and hydrochloric acid solution with a mass fraction of 36% are mixed at a mass ratio of 1:2, then filtered and dried. Then it is added to 10 times the mass of dichloromethane of the composite curing agent and stirred and mixed for 45 min. Subsequently, the premix obtained in step (1) is added and the stirring reaction continues for 3 h. Dichloromethane is removed by rotary evaporation at 45 °C to obtain a secondary mixture;

[0081] (3) 382 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator are manually mixed evenly, and then extruded into sheet materials by melt mixing using a twin-screw extruder with a rotation speed of 35 rpm. After the sheet materials are cooled, they are ground in a high-speed grinder and passed through a 160-mesh sieve to obtain a flame retardant and insulating powder coating for new energy vehicles; the temperature setting of the extruder: zone I 85 °C, zone II 100 °C.

[0082] Among them, the preparation steps of the toughening agent are as follows: 16.42 parts by mass of N-p-coumaroyltyramine is dissolved in 72 parts by mass of 1,4-dioxane, and then 11.1 parts by mass of isophorone diisocyanate trimer is added dropwise at 2 drops / s. After heating to 80 °C and stirring for 4 h, a mixed solution of 79.85 parts by mass of 4-bromophenol is added. Among them, 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and the stirring reaction continues for 4 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 70 °C to obtain the toughening agent.

[0083] The preparation steps of the modified flame retardant filler are as follows: Add 2.4 parts by mass of dopamine hydrochloride and 6 parts by mass of hexagonal boron nitride into 1000 parts by mass of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 30 min, stir and react at room temperature for 24 h. After the reaction is completed, perform vacuum filtration. Wash the precipitate with deionized water until the filtrate is colorless, and then dry it at 60 °C for 24 h to obtain hexagonal boron nitride wrapped with polydopamine. Add 10 parts by mass of the hexagonal boron nitride wrapped with polydopamine into an ethanol-water solution with a volume ratio of 49:1, and then add 0.5 parts by mass of a silane coupling agent. Ultrasonic for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at a high speed of 6000 rpm for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame retardant filler.

[0084] The silane coupling agent is a mercapto silane coupling agent.

[0085] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functionalized organopolysiloxane in a mass ratio of 1:0.5.

[0086] (Comparative Example 4)

[0087] A preparation method of a flame retardant and insulating powder coating for new energy vehicles, the preparation steps include:

[0088] (1) Slowly add 5 parts by mass of a toughening agent and 0.25 parts by mass of iodine to 5.7 parts by mass of magnesium powder and 55 parts by mass of anhydrous ether under stirring, then heat to a slightly boiling state, and dropwise add a mixed solution of 112 parts by mass of the toughening agent and ether within 60 min, and finish dropping within 60 min, then reflux for 3 h. Among them, the mass of the toughening agent in the mixed solution of the toughening agent and ether is 52 parts by mass, and the mass of ether is 60 parts by mass. After cooling to room temperature, add 57.5 parts by mass of an ether dispersion of hexagonal boron nitride, and after adding it within 60 min, reflux and react for 5 h and then cool to room temperature. Among them, the mass of hexagonal boron nitride in the ether dispersion of hexagonal boron nitride is 7.5 parts by mass, and the mass of ether is 50 parts by mass. Then add 50 parts by mass of methanol and stir at room temperature for 60 min, filter, and dry at 70 °C overnight under nitrogen protection to obtain a premix;

[0089] (2) Mix 100.5 parts by mass of the composite curing agent and a hydrochloric acid solution with a mass fraction of 36% in a mass ratio of 1:2, then filter and dry, then add it to dichloromethane 10 times the mass of the composite curing agent and stir and mix for 45 min, then add the premix obtained in step (1) and continue to stir and react for 3 h, and remove dichloromethane by rotary evaporation at 45 °C to obtain a secondary premix;

[0090] (3) Manually mix 382 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of a leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of a promoter evenly, and then use a twin-screw extruder with a rotational speed of 35 rpm to extrude sheet materials through melt mixing. After the sheet materials are cooled, they are ground in a high-speed grinder and passed through a 160-mesh sieve to obtain a flame-retardant insulating powder coating for new energy vehicles; the temperature settings of the extruder are: zone I 85 °C, zone II 100 °C.

[0091] Among them, the preparation steps of the toughening agent are as follows: Dissolve 16.42 parts by mass of N-p-coumaroyltyramine in 72 parts by mass of 1,4-dioxane, and then drop 11.1 parts by mass of isophorone diisocyanate trimer at a rate of 2 drops / s. After heating to 80 °C and stirring for 4 h, add a mixed solution of 79.85 parts by mass of 4-bromophenol, among which 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and continue to stir and react for 4 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 70 °C to obtain the toughening agent.

[0092] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-thiol-functionalized organopolysiloxane in a mass ratio of 1:0.5.

[0093] (Comparative Example 5)

[0094] A preparation method of a flame-retardant insulating powder coating for new energy vehicles, the preparation steps include:

[0095] (1) Slowly add 5 parts by mass of a toughening agent and 0.25 part by mass of iodine to 5.7 parts by mass of magnesium powder and 55 parts by mass of anhydrous ether under stirring, and then heat to a slightly boiling state. Drop a mixed solution of 112 parts by mass of the toughening agent and ether within 60 min, and finish dropping within 60 min. Then reflux for 3 h, among which the mass of the toughening agent in the mixed solution of the toughening agent and ether is 52 parts by mass, and the mass of ether is 60 parts by mass; after cooling to room temperature, add 57.5 parts by mass of an ether dispersion of a modified flame-retardant filler. After adding it within 60 min, reflux and react for 5 h and then cool to room temperature, among which the mass of the modified flame-retardant filler in the ether dispersion of the modified flame-retardant filler is 7.5 parts by mass, and the mass of ether is 50 parts by mass; then add 50 parts by mass of methanol and stir at room temperature for 60 min, filter, and dry overnight at 70 °C under nitrogen protection to obtain a premix;

[0096] (2) Mix 100.5 parts by mass of the composite curing agent and a hydrochloric acid solution with a mass fraction of 36% in a mass ratio of 1:2, then filter and dry, then add it to dichloromethane 10 times the mass of the composite curing agent and stir and mix for 45 min, then add the premix obtained in step (1) and continue to stir and react for 3 h, and remove dichloromethane by rotary evaporation at 45 °C to obtain a secondary mixture;

[0097] (3) Manually mix 382 parts by mass of epoxy resin, the secondary mixture obtained in step (2), 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator evenly, and then use a twin-screw extruder with a rotation speed of 35 rpm to extrude sheet materials through melt mixing. After the sheet materials are cooled, they are ground in a high-speed grinder and passed through a 160-mesh sieve to obtain a flame-retardant insulating powder coating for new energy vehicles; the temperature of the extruder is set as follows: zone I is 85 °C, and zone II is 100 °C.

[0098] Among them, the preparation steps of the toughening agent are as follows: Dissolve 16.42 parts by mass of N-p-coumaroyltyramine in 72 parts by mass of 1,4-dioxane, and then drop 11.1 parts by mass of isophorone diisocyanate trimer at a rate of 2 drops per second. After heating to 80 °C and stirring for 4 h, add a mixed solution of 79.85 parts by mass of 4-bromophenol, where 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and continue to stir and react for 4 h. After the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 70 °C to obtain the toughening agent.

[0099] The preparation steps of the modified flame-retardant filler are as follows: Add 2.4 parts by mass of hydrochloric acid dopamine and 6 parts by mass of hexagonal boron nitride to 1000 parts by mass of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5, ultrasonically treat for 30 min, and then stir and react at room temperature for 24 h. After the reaction is completed, vacuum filtration is carried out, and the precipitate is washed with deionized water until the filtrate is colorless, and then dried at 60 °C for 24 h to obtain hexagonal boron nitride wrapped with polydopamine; Add 10 parts by mass of hexagonal boron nitride wrapped with polydopamine to an ethanol aqueous solution with a volume ratio of 49:1, then add 0.5 part by mass of silane coupling agent, ultrasonically treat for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at 6000 rpm at high speed for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame-retardant filler.

[0100] The silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:1.

[0101] The composite curing agent is 4,4-diaminodiphenylmethane.

[0102] (Comparative Example 6)

[0103] A preparation method of a flame-retardant insulating powder coating for new energy vehicles, the preparation steps include:

[0104] Mix 382 parts by mass of epoxy resin, 57 parts by mass of toughening agent, 7.5 parts by mass of modified flame retardant filler, 100.5 parts by mass of composite curing agent, 5 parts by mass of leveling agent, 1 part by mass of benzoin, and 0.7 part by mass of accelerator manually and evenly. Then, use a twin-screw extruder with a rotation speed of 35 rpm to melt and knead and extrude sheet materials through it. After the sheet materials are cooled, grind them in a high-speed grinder and pass through a 160-mesh sieve to obtain a flame retardant and insulating powder coating for new energy vehicles. The temperature setting of the extruder: Zone I is 85 °C, and Zone II is 100 °C.

[0105] Among them, the preparation steps of the toughening agent are as follows: Dissolve 16.42 parts by mass of N-p-coumaroyltyramine in 72 parts by mass of 1,4-dioxane, and then drop 11.1 parts by mass of isophorone diisocyanate trimer at a rate of 2 drops / s. Raise the temperature to 80 °C and stir and react for 4 h. Then, add a mixed solution of 79.85 parts by mass of 4-bromophenol, among which 7.85 parts by mass of 4-bromophenol is dissolved in 72 parts by mass of 1,4-dioxane, and continue to stir and react for 4 h. After the reaction is completed, rotary evaporate to remove the solvent 1,4-dioxane at 70 °C to obtain the toughening agent.

[0106] The preparation steps of the modified flame retardant filler are as follows: Add 2.4 parts by mass of hydrochloric acid dopamine and 6 parts by mass of hexagonal boron nitride to 1000 parts by mass of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a concentration of 10 mmol / L and a pH of 8.5. After ultrasonic treatment for 30 min, stir and react at room temperature for 24 h. After the reaction is completed, perform vacuum filtration, wash the precipitate with deionized water until the filtrate is colorless, and then dry it at 60 °C for 24 h to obtain hexagonal boron nitride encapsulated with polydopamine; Add 10 parts by mass of hexagonal boron nitride encapsulated with polydopamine to an ethanol aqueous solution with a volume ratio of 49:1, then add 0.5 part by mass of silane coupling agent, ultrasonic for 20 min, stir at 80 °C at 500 rpm for 6 h, then centrifuge at 6000 rpm at high speed for 10 min, wash with ethanol 3 times, and vacuum dry at 60 °C for 24 h to obtain the modified flame retardant filler.

[0107] The silane coupling agent is obtained by combining 4-benzonitrile oxybutyltrimethoxysilane and mercapto silane coupling agent in a mass ratio of 1:1.

[0108] The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functional organic polysiloxane in a mass ratio of 1:0.5.

[0109] Effect example

[0110] Spray the flame retardant and insulating powder coatings for new energy vehicles prepared in the examples and comparative examples on the substrate in the form of electrostatic spraying, and then cure and form a film in an oven at 200 °C for 15 min to obtain a 150-μm-thick flame retardant and insulating coating.

[0111] Appearance performance test: It is carried out according to the method of HG / T 2006—2006 "Thermosetting Powder Coatings". Among them, the appearance performance of the flame-retardant insulating coatings prepared in the examples and comparative examples is observed by visual method according to part 5.9 for the occurrence of pinholes.

[0112] Impact resistance test: Referring to "GB / T 1732-2020 Determination of Film Impact Resistance", the forward and reverse impact performance tests are carried out on the flame-retardant insulating coatings prepared in the examples and comparative examples using a film impact tester. The cured sample plate is placed flat on the base of the impact tester, and a 1 kg weight is freely dropped from a certain height to impact the coating forward or backward. After the test, the sample plate is taken out, and a magnifying glass is used to observe whether there are cracks, wrinkles and peeling phenomena at the impact point.

[0113] Bending test: The T-bend of the flame-retardant insulating coatings prepared in the examples and comparative examples is detected referring to "GB / T 30791—2014 Paints and Varnishes T-bend Test".

[0114] Flammability test: The flame-retardant insulating powder coatings for new energy vehicles prepared in the examples and comparative examples are tested according to the "UL94 Flammability Test Method and Standard". Among them, for V0, the coating does not burn with high temperature and open fire.

[0115] Corrosion resistance: According to "GB / T 1771-2007 Paints and Varnishes - Determination of Resistance to Neutral Salt Spray", a salt spray test machine is used to test the flame-retardant insulating coatings prepared in the examples and comparative examples; a cross is scratched on the test sample plate with a cutter until the bottom plate is reached and then placed in a salt spray chamber, and a 500 h salt spray test is carried out with a sodium chloride solution, and the corrosion length is measured by peeling off the rust.

[0116] Insulation performance: Referring to "GB / T 1408.1-2016 Insulating Materials - Electrical Strength Test Methods", a voltage breakdown tester is used to test whether the flame-retardant insulating coating meets the breakdown voltage requirement of ≥5 kV.

[0117] Self-healing performance: The flame-retardant insulating powder coatings for new energy vehicles prepared in the examples and comparative examples are made into standard specimens according to "GB / T1040.1-2018 Plastics - Determination of Tensile Properties - Part 1: General Principles", and the original tensile strength is tested with a tensile machine. Then, an un-stretched original specimen is cut with a crack with a depth of 2 mm and a length of 10 mm in the middle, placed in a mold, and kept at a humidity of 70% and a temperature of 80 °C for 24 h to observe whether the specimen is repaired.

[0118] The following Table 1 shows the performance test results of the flame-retardant insulating powder coatings for new energy vehicles and the flame-retardant insulating coatings prepared in the examples and comparative examples:

[0119] Table 1

[0120] Apparent properties Impact strength / cm T bend Corrosion length / mm Flame retardancy Insulation performance Self-healing performance Example 1 Smooth, bright and delicate 60 times of forward and reverse impact 1T 0.19 V0 Breakdown voltage meets the requirements Crack repair Example 2 Smooth, bright and delicate 65 times of forward and reverse impact 1T 0.16 V0 Breakdown voltage meets the requirements Crack repair Example 3 Smooth, bright and delicate 65 times of forward and reverse impact 1T 0.18 V0 Breakdown voltage meets the requirements Crack repair Comparative example 1 There are pinholes on the coating surface 55 times of forward and reverse impact 2T 0.18 V0 Breakdown voltage meets the requirements Crack repair Comparative example 2 Smooth, bright and delicate 55 times of forward and reverse impact 1T 0.19 V0 Breakdown voltage meets the requirements Crack not repaired Comparative example 3 There are pinholes on the coating surface 55 times of forward and reverse impact 1T 0.17 V0 Breakdown voltage meets the requirements Crack repair Comparative example 4 There are pinholes on the coating surface Failed in 50 times of forward impact 3T 0.51 V1 Breakdown voltage meets the requirements Crack not repaired Comparative example 5 Smooth, bright and delicate 55 times of forward and reverse impact 2T 0.28 V1 Breakdown voltage meets the requirements Crack not repaired Comparative example 6 There are pinholes on the coating surface 60 times of forward and reverse impact 2T 0.17 V0 Breakdown voltage meets the requirements Crack repair

[0121] As can be seen from Table 1, by comparing Examples 1-3 with Comparative Examples 1-6, it can be obtained that the flame retardancy, insulation performance, corrosion resistance, toughness, impact resistance, and appearance performance of the flame-retardant and insulating powder coatings for new energy vehicles prepared in Examples 1-3 are better, and they have self-healing performance.

[0122] The difference between Comparative Example 1 and Example 2 is that the flame-retardant and insulating powder coating for new energy vehicles in Comparative Example 1 does not add a toughening agent, and directly mixes epoxy resin, modified flame-retardant filler, composite curing agent, leveling agent, benzoin, and accelerator, omitting the preparation of the premix in step (1) and the secondary mixture treatment in step (2) in Example 2, and it is impossible to form benzophenone imine derivatives in the flame-retardant and insulating powder coating for new energy vehicles. Compared with Comparative Example 1, the toughness, impact resistance, and appearance performance of the flame-retardant and insulating powder coating in Example 2 are better.

[0123] The difference between Comparative Example 2 and Example 2 is that the silane coupling agent of the modified flame-retardant filler in Comparative Example 2 only uses 4-benzonitrile oxybutyltrimethoxysilane and does not use mercapto silane coupling agent. Compared with Comparative Example 1, the impact resistance of the flame-retardant and insulating powder coating for new energy vehicles in Example 2 is better, and it has self-healing performance.

[0124] The difference between Comparative Example 3 and Example 2 is that the silane coupling agent of the modified flame-retardant filler in Comparative Example 3 does not use 4-benzonitrile oxybutyltrimethoxysilane and only uses mercapto silane coupling agent, and it is also impossible to form benzophenone imine derivatives in the flame-retardant and insulating powder coating for new energy vehicles. Compared with Comparative Example 3, the appearance performance and impact resistance of the flame-retardant and insulating powder coating for new energy vehicles in Example 2 are better.

[0125] The difference between Comparative Example 4 and Example 2 is that Comparative Example 4 directly uses the ether dispersion of hexagonal boron nitride to prepare the flame-retardant and insulating powder coating for new energy vehicles, and it is also impossible to form benzophenone imine derivatives in the flame-retardant and insulating powder coating for new energy vehicles. Compared with Comparative Example 4, the toughness, impact resistance, appearance performance, and flame retardancy of the flame-retardant and insulating powder coating for new energy vehicles in Example 2 are better, and it has self-healing performance.

[0126] The difference between Comparative Example 5 and Example 2 is that the curing agent in Comparative Example 5 only uses 4,4-diaminodiphenylmethane. Compared with Comparative Example 5, the flame retardancy, corrosion resistance, toughness, impact resistance, and appearance performance of the flame-retardant and insulating powder coating for new energy vehicles in Example 2 are better, and it has self-healing performance.

[0127] The difference between Comparative Example 6 and Example 2 is that in the preparation of the flame-retardant insulating powder coating for new energy vehicles in Comparative Example 6, the raw material components were directly mixed and melt-extruded; the benzophenone imine derivative could not be formed during the preparation process. Compared with Comparative Example 6, the appearance properties of the flame-retardant insulating powder coating for new energy vehicles in Example 2 are better.

[0128] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flame retardant insulating powder coating for new energy vehicles, characterized in that: The raw material components include, by weight: 380-384 parts by weight of epoxy resin, 56-58 parts by weight of toughening agent, 5-10 parts by weight of modified flame retardant filler, 100-101 parts by weight of composite curing agent, 5 parts by weight of leveling agent, 1 part by weight of benzoin, and 0.7 parts by weight of accelerator; The toughening agent is obtained by reacting isophorone diisocyanate trimer, 4-bromophenol and N-p-coumaryl tyramine; The modified flame retardant filler is obtained by first wrapping hexagonal boron nitride with polydopamine and then modifying it with a silane coupling agent; The silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and mercaptosilane coupling agent; The composite curing agent includes 4,4-diaminodiphenylmethane and amino-mercapto-functional organopolysiloxane; The flame-retardant insulating powder coating for new energy vehicles is prepared by first reacting a toughening agent and magnesium in anhydrous ether, introducing iodine to initiate the reaction during the reaction, then adding a modified flame-retardant filler for a premixing reaction, then adding methanol for alcoholysis to obtain a premix, then remixing the premix with a composite curing agent, and finally melt-mixing and extruding the premix with an epoxy resin, a leveling agent, benzoin, and an accelerator.

2. A method for preparing a flame retardant insulating powder coating for new energy vehicles as claimed in claim 1, characterized in that: The preparation steps include: (1) Slowly add 5 parts by mass of toughening agent and 0.24 to 0.26 parts by mass of iodine to 5.6 to 5.8 parts by mass of magnesium powder and 50 to 60 parts by mass of anhydrous ether under stirring, then heat to a slightly boiling state, and dropwise add 101 to 123 parts by mass of a mixture of toughening agent and ether under a slightly boiling state, and complete the dropwise addition within 60 minutes, and then reflux for 2.5 to 3.5 hours, wherein the mass of toughening agent in the mixture of toughening agent and ether is 51 to 53 parts by mass, and the mass of ether is 50 to 70 parts by mass. After cooling to room temperature, add 45-70 parts by mass of ether dispersion of modified flame retardant filler, add within 60 minutes, reflux for 4.5-5.5 hours and then cool to room temperature, wherein the mass of modified flame retardant filler in the ether dispersion of modified flame retardant filler is 5-10 parts by mass, and the mass of ether is 40-60 parts by mass; then add 40-60 parts by mass of methanol, stir at room temperature for 50-70 minutes, filter, and dry overnight at 70°C under nitrogen protection to obtain a premix; (2) 100-101 parts by weight of the composite curing agent and 36% hydrochloric acid solution are mixed in a mass ratio of 1:1.8-2.2, followed by filtration and drying, followed by adding 5-15 times the mass of the composite curing agent into dichloromethane and stirring for 30-60 minutes, followed by adding the premix obtained in step (1) and continuing to stir and react for 2-4 hours, and removing dichloromethane by rotary evaporation at 40-50° C. to obtain a secondary mixture; (3) 380-384 parts by weight of epoxy resin, the secondary mixture obtained in step (2), 5 parts by weight of leveling agent, 1 part by weight of benzoin, and 0.7 parts by weight of accelerator were manually mixed and then extruded into sheets by melt mixing using a twin-screw extruder at a speed of 35 rpm. After the sheets were cooled, they were ground in a high-speed pulverizer and passed through a 160-mesh sieve to obtain a flame-retardant insulating powder coating for new energy vehicles.

3. The method for preparing the flame retardant insulating powder coating for new energy vehicles according to claim 2, characterized in that: The preparation steps of the toughening agent are as follows: 16.4-16.44 parts by mass of N-p-coumaryltyramine is dissolved in 70-74 parts by mass of 1,4-dioxane, then 11-11.2 parts by mass of isophorone diisocyanate trimer is added at 1-3s / drop, the temperature is raised to 78-82°C and stirred for reaction for 3.5-4.5h, and then 77.8-81.9 parts by mass of a mixed solution of 4-bromophenol is added, wherein 7.8-7.9 parts by mass of 4-bromophenol is dissolved in 70-74 parts by mass of 1,4-dioxane, the stirring reaction is continued for 3.5-4.5h, and after the reaction is completed, the solvent 1,4-dioxane is removed by rotary evaporation at 68-72°C to obtain the toughening agent.

4. The method for preparing the flame retardant insulating powder coating for new energy vehicles according to claim 2, characterized in that: The preparation steps of the modified flame retardant filler are as follows: 2.2-2.6 parts by mass of dopamine hydrochloride and 5-7 parts by mass of hexagonal boron nitride are added to 1000 parts by mass of 10 mmol / L, pH 8.5 tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution, ultrasonically treated for 25-35 minutes, stirred at room temperature for reaction for 23-25 ​​hours, vacuum filtered after the reaction, washed the precipitate with deionized water until the filtrate was colorless, and then dried at 60°C for 23-25 ​​hours to obtain polydopamine-wrapped hexagonal boron nitride; 9-11 parts by weight of hexagonal boron nitride wrapped with polydopamine were added to an ethanol aqueous solution with a volume ratio of 49:1, and then 0.4-0.6 parts by weight of a silane coupling agent were added, ultrasonicated for 15-25 minutes, stirred at 500 rpm for 5.5-6.5 hours at 78-82°C, and then centrifuged at 6000 rpm for 10 minutes, washed with ethanol for multiple times, and vacuum dried at 60°C for 23-25 ​​hours to obtain a modified flame retardant filler.

5. The method for preparing the flame retardant insulating powder coating for new energy vehicles according to claim 4, characterized in that: The silane coupling agent is obtained by combining 4-benzonitrileoxybutyltrimethoxysilane and mercaptosilane coupling agent in a mass ratio of 1:0.8-1.

2.

6. The method for preparing the flame retardant insulating powder coating for new energy vehicles according to claim 2, characterized in that: The composite curing agent is obtained by combining 4,4-diaminodiphenylmethane and amino-mercapto functional organic polysiloxane in a mass ratio of 1:0.4-0.6.