Preparation method and application of flame-retardant material

Abstract

According to the preparation method of the flame-retardant material provided by the invention, a radiation curing mode is adopted, so that the internal curing uniformity of the flame-retardant material is improved; through copper stearate treatment and amination modification of aluminum hydroxide, the uniformity of the flame retardant property is improved; through sulfonation reaction, isocyanuric acid 2-hydroxyethyl ester and ammonium nitrate treatment, the limit oxygen index is increased; through zinc oxide treatment, the limit oxygen index is increased, and meanwhile sulfur dioxide and other toxic gases generated at high temperature are absorbed; through boron carbide and bismuth oxide treatment, the limit oxygen index is increased, and meanwhile the anti-radiation performance is provided; through particle size control, the light transmittance of the flame-retardant material is improved, and the requirements of industrial fields such as new energy automobiles on high-performance flame-retardant materials are met.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, and in particular to a preparation method of a flame retardant material and application thereof. Background Art

[0002] With the rapid development of new energy vehicles, electronic equipment, aerospace and other fields, the demand for high-performance flame retardant materials is growing. Traditional flame retardant materials mostly use halogen compounds as flame retardants. Such flame retardant materials are prone to produce toxic and harmful substances such as dioxins at high temperatures, which further causes safety issues during fires or waste disposal. In addition to the above-mentioned secondary safety issues, traditional flame retardant materials also have the following problems in terms of performance:

[0003] (1) Insufficient curing uniformity: Existing materials mostly rely on thermal curing processes. However, the thermal curing process has uneven heat transfer, resulting in over-curing of the surface layer and under-curing of the inner layer, causing fluctuations in mechanical properties (such as cracks and delamination), which is especially obvious in thick-walled or complex structures.

[0004] (2) The contradiction between flame retardant efficiency and uniformity: Inorganic flame retardants have high surface polarity and are easy to agglomerate in the polymer matrix, resulting in uneven dispersion and a decrease in local flame retardant performance. Although organic flame retardants (such as phosphorus compounds) have good dispersibility, they are easy to decompose and become ineffective at high temperatures, making it difficult to achieve both long-term flame retardancy and mechanical stability.

[0005] (3) The improvement of limiting oxygen index (LOI) is limited: the LOI of traditional compound systems (such as phosphorus-nitrogen synergy) is mostly lower than 35%, which is difficult to meet the stringent requirements of LOI>40% in high-risk scenarios such as new energy vehicle battery compartments. In addition, the existing technology rarely involves the treatment of toxic gases (such as SO 2 , HCN) absorption design poses a risk of secondary pollution.

[0006] (4) Single function: Most flame retardant materials lack additional functions such as radiation protection and light transmittance regulation. For example, the battery compartment of new energy vehicles requires flame retardant materials with gamma ray shielding capabilities to cope with electromagnetic radiation; while the on-board display components require materials to maintain a certain light transmittance while being flame retardant, which is difficult to achieve with existing technologies.

[0007] In response to the above problems, it is urgent to develop a new type of flame retardant material to improve the performance of limiting oxygen index, radiation protection and light transmittance through innovative processes such as multi-component synergy, nano-dispersion and radiation curing. Summary of the invention

[0008] In order to solve the above problems, the first aspect of the present invention provides a method for preparing a flame retardant material, comprising the following steps:

[0009] A method for preparing a flame retardant material, characterized in that it comprises the following steps:

[0010] Step S1, condensation reaction of phenol and catechol: adding phenol and catechol into a reaction kettle to carry out condensation reaction; collecting heavy fractions by vacuum distillation, washing and drying, and preparing product A;

[0011] Step S2, sulfonation reaction: adding product A and sulfuric acid into a reactor to carry out sulfonation reaction, and after the reaction is completed, pouring the sulfonation reaction solution into an ice-water mixture to precipitate, collecting the precipitate by filtration, washing and drying to obtain product B;

[0012] Step S3, zinc oxide treatment: uniformly mixing the product B with zinc oxide to prepare a mixture C;

[0013] Step S4, aminated aluminum hydroxide: dissolving a titanate coupling agent in anhydrous ethanol to prepare a titanate solution; mixing water and aluminum hydroxide, adjusting the pH to 4.5-5.5 to prepare a suspension, adding the titanate solution to the suspension to perform an amination reaction to form a reaction solution D;

[0014] Step S5, boron carbide and bismuth oxide treatment: adding boron carbide and bismuth oxide nanoparticles to the reaction solution D; collecting the precipitate by centrifugation to prepare a mixture E;

[0015] Step S6, controlling the particle size of the mixture F: controlling the particle size of the mixture E to be 20 nm to 40 nm by grinding to prepare a mixture F;

[0016] Step S7, condensation reaction of mixture C and 2-hydroxyethyl isocyanurate: adding mixture C, 2-hydroxyethyl isocyanurate, mixture F and paraformaldehyde into a reaction kettle to carry out condensation reaction; collecting heavy fractions by vacuum distillation, recrystallizing with ethanol and drying to obtain product G;

[0017] Step S8, epoxy resin synthesis: dissolving product G in epichlorohydrin, adding tetramethylammonium chloride, and dropping a 50% by mass sodium hydroxide aqueous solution to perform a pre-reaction; then performing a ring-opening reaction of epichlorohydrin; cooling to 20° C. to 30° C. to terminate the reaction; adding deionized water for washing, collecting the organic phase; and removing the solvent by distillation under reduced pressure to obtain product H;

[0018] Step S9, copper stearate treatment: adding copper stearate to ammonium nitrate and dispersing the mixture evenly to prepare a mixture I;

[0019] Step S10, ammonium nitrate treatment: adding mixture I to product H, mixing evenly, to prepare mixture J;

[0020] Step S11, adding triphenylphosphine oxide: adding triphenylphosphine oxide to mixture J, mixing evenly, to prepare mixture K;

[0021] Step S12, electrostatic spinning: dissolving the mixture K in a mixture of ethanol and acetone, and performing electrostatic spinning to form fibers L; the fibers L are dried to form fibers M;

[0022] Step S13, electron beam radiation curing: the fiber M is cured by electron beam radiation to form a flame retardant material.

[0023] As a preferred technical solution, the condensation reaction time of step S1 is 4 hours to 6 hours, the condensation reaction temperature is 100°C to 120°C; the condensation reaction solvent is a mixed solution of toluene and ethanol, and the volume ratio of toluene to ethanol is 2:(1-1.2); the molar ratio of phenol to catechol is 1:(1-1.2); the condensation reaction catalyst is p-toluenesulfonic acid, and the condensation reaction pH value is 4-5.

[0024] As a preferred technical solution, the mass ratio of product A to sulfuric acid in step S2 is 1:(1.0-1.5); the sulfonation reaction temperature is 80°C-100°C, and the sulfonation reaction time is 3 hours-5 hours; the sulfuric acid mass concentration is 20%; the drying temperature is 60°C-80°C; and the mass ratio of the sulfonation reaction liquid to the ice-water mixture is 1:5.

[0025] As a preferred technical solution, the mass ratio of product B to zinc oxide in step S3 is 1:(0.02-0.05).

[0026] As a preferred technical solution, the mass ratio of water to aluminum hydroxide in step S4 is 2:1; the mass ratio of titanate to aluminum hydroxide is (0.02-0.04):1; the temperature of the first stage of the amination reaction is 60°C-65°C, and the time of the first stage of the amination reaction is 1 hour-2 hours; the temperature of the second stage of the amination reaction is 80°C-85°C, and the time of the second stage of the amination reaction is 1 hour-2 hours.

[0027] As a preferred technical solution, the mass ratio of aluminum hydroxide to boron carbide and bismuth oxide in the reaction solution D of step S5 is 1:(0.008-0.01):(0.01-0.015).

[0028] As a preferred technical solution, the condensation reaction time in step S7 is 4 hours to 6 hours, and the condensation reaction temperature is 80°C to 100°C; the condensation reaction solvent is a mixture of dioxane and water, and the volume ratio of dioxane to water is 1:(1-1.2); the mass ratio of mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde is 1:(0.8-1.0):(0.3-0.5):(1.4-1.6); the condensation reaction catalyst is sodium hydroxide, and the condensation reaction pH value is 8-9.

[0029] As a preferred technical solution, in step S8, the pre-reaction temperature is 45°C to 55°C, and the pre-reaction time is 2 hours to 3 hours; the ring-opening reaction temperature is 75°C to 85°C, and the ring-opening reaction time is 4 hours to 5 hours; the mass ratio of the product G to epichlorohydrin is 1:(4-6); the mass ratio of the product G to tetramethylammonium chloride is 1:(0.02-0.04); the mass ratio of the product G to 50% aqueous sodium hydroxide solution is 1:(3-5).

[0030] As a preferred technical solution, the mass ratio of ammonium nitrate to copper stearate in step S9 is 1:(0.05-0.1).

[0031] As a preferred technical solution, in step S10, the mass ratio of the product H to the mixture I is 1:(0.3-0.7).

[0032] As a preferred technical solution, the mass ratio of the mixture J to triphenylphosphine oxide in step S11 is 1:(0.02-0.04).

[0033] As a preferred technical solution, the volume ratio of ethanol to acetone in the ethanol-acetone mixture in step S12 is 3:1; the electrospinning voltage is 15kV to 25kV; the receiving distance is 15cm to 25cm; the temperature is 20℃ to 25℃; the mass ratio of the mixture K to the mixed liquid is 1:(3-5); the diameter of the fiber L is 10 microns to 30 microns; the drying time is 2 hours to 3 hours; and the drying temperature is 60℃ to 70℃.

[0034] As a preferred technical solution, in step S13, the radiation dose is 20 kGy to 30 kGy; the electron beam energy is 200 keV to 300 keV; and the curing temperature is 20° C. to 30° C.

[0035] The second aspect of the present invention provides a flame retardant material, which is made by the above-mentioned preparation method.

[0036] The third aspect of the present invention provides the application of flame retardant materials in new energy vehicles. The flame retardant materials can be used as interlayer materials in the cabin, battery compartment, etc. of the car to provide higher fire resistance for the car and improve the safety of the car.

[0037] Through the above technical solutions, the present invention produces the following technical effects:

[0038] (1) Using radiation curing to improve the internal curing uniformity of flame retardant materials;

[0039] (2) Improve the uniformity of flame retardant properties by treating aluminum hydroxide with copper stearate and amino modification;

[0040] (3) Improving the limiting oxygen index through sulfonation reaction, 2-hydroxyethyl isocyanurate, and ammonium nitrate treatment;

[0041] (4) Through zinc oxide treatment, the limiting oxygen index is increased, and toxic gases such as sulfur dioxide generated by high temperature are absorbed;

[0042] (5) Through the treatment of boron carbide and bismuth oxide, the limiting oxygen index is improved and radiation protection performance is provided;

[0043] (6) Improve the light transmittance of flame retardant materials by controlling particle size. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the applicant further describes them through specific embodiments.

[0045] Embodiment 1:

[0046] Step S1, condensation reaction of phenol and catechol: phenol and catechol are added into a reaction kettle to carry out condensation reaction; then the heavy fraction is collected by vacuum distillation, washed and dried to prepare product A; the condensation reaction time is 4 hours, the condensation reaction temperature is 100°C; the condensation reaction solvent is a mixed solution of toluene and ethanol, the volume ratio of toluene to ethanol is 2:1; the molar ratio of phenol to catechol is 1:1; the condensation reaction catalyst is p-toluenesulfonic acid, and the condensation reaction pH value is 4;

[0047] Step S2, sulfonation reaction: product A and sulfuric acid are added to a reactor in a mass ratio of 1:1 to carry out a sulfonation reaction. After the reaction is completed, the sulfonation reaction liquid is poured into an ice-water mixture to precipitate, the precipitate is collected by filtration, and the product B is obtained by washing and drying; the sulfonation reaction temperature is 80° C., the sulfonation reaction time is 3 hours; the mass concentration of sulfuric acid is 20%; the drying temperature is 60° C.; the mass ratio of the sulfonation reaction liquid to the ice-water mixture is 1:5;

[0048] Step S3, zinc oxide treatment: uniformly mixing product B and zinc oxide to prepare mixture C; the mass ratio of product B to zinc oxide is 1:0.02;

[0049] Step S4, aminated aluminum hydroxide: dissolving a titanate coupling agent in anhydrous ethanol to prepare a titanate solution; mixing water and aluminum hydroxide, adjusting the pH to 4.5 to prepare a suspension, wherein the mass ratio of water to aluminum hydroxide is 2:1; adding the titanate solution to the suspension to perform an amination reaction to form a reaction solution D; the mass ratio of the titanate coupling agent to the aluminum hydroxide is 0.02:1; the amination reaction temperature is 60°C, and stirring is continued for 1 hour; heating to 80°C, and stirring is continued for 1 hour;

[0050] Step S5, boron carbide and bismuth oxide treatment: adding boron carbide and bismuth oxide nanoparticles to the reaction solution D; the mass ratio of aluminum hydroxide to boron carbide and bismuth oxide in the reaction solution D is 1:0.008:0.01; collecting the precipitate by centrifugation to prepare a mixture E;

[0051] Step S6, particle size control of mixture F: the particle size of mixture E is controlled to be 20 nm by grinding to prepare mixture F;

[0052] Step S7, condensation reaction of mixture C and 2-hydroxyethyl isocyanurate: mixture C, 2-hydroxyethyl isocyanurate, mixture F, and polyformaldehyde are added to a reactor to carry out a condensation reaction; heavy fractions are collected by vacuum distillation, and the product G is obtained by recrystallization and drying through ethanol; the condensation reaction time is 4 hours, and the condensation reaction temperature is 80° C. The condensation reaction solvent is a mixture of dioxane and water, and the volume ratio of dioxane to water is 1:1; the mass ratio of mixture C, 2-hydroxyethyl isocyanurate, mixture F, and polyformaldehyde is 1:0.8:0.3:1.4; the condensation reaction catalyst is sodium hydroxide, and the condensation reaction pH value is 8;

[0053] Step S8, epoxy resin synthesis: dissolving product G in epichlorohydrin, adding tetramethylammonium chloride, and dropping a 50% sodium hydroxide aqueous solution in a mass ratio to conduct a pre-reaction at a temperature of 45° C. for 2 hours; then conducting a ring-opening reaction of epichlorohydrin at a temperature of 75° C. for 4 hours; the mass ratio of product G to epichlorohydrin is 1:4; the mass ratio of product G to tetramethylammonium chloride is 1:0.02; the mass ratio of product G to 50% sodium hydroxide aqueous solution is 1:3; cooling to 20° C. to terminate the reaction; adding water for washing, collecting the organic phase; removing the solvent by reduced pressure distillation to obtain product H;

[0054] Step S9, copper stearate treatment: adding copper stearate to ammonium nitrate and dispersing the mixture evenly to prepare a mixture I; the mass ratio of ammonium nitrate to copper stearate is 1:0.05;

[0055] Step S10, ammonium nitrate treatment: adding mixture I to product H, mixing evenly, to prepare mixture J; the mass ratio of product H to mixture I is 1:0.3;

[0056] Step S11, adding triphenylphosphine oxide: adding triphenylphosphine oxide to mixture J, mixing evenly, to prepare mixture K; the mass ratio of mixture J to triphenylphosphine oxide is 1:0.02;

[0057] Step S12, electrostatic spinning: dissolving the mixture K in a mixture of ethanol and acetone, and performing electrostatic spinning to prepare fiber L; the volume ratio of ethanol to acetone in the mixture of ethanol and acetone is 3:1; the electrostatic spinning voltage is 15 kV, the receiving distance is 15 cm, and the temperature is 20°C; the mass ratio of the mixture K to the mixture of ethanol and acetone is 1:3; the diameter of the fiber L is 10 microns; the fiber L is dried to prepare fiber M; the drying time is 2 hours; and the drying temperature is 60°C;

[0058] Step S13, electron beam radiation curing: the fiber M is cured by electron beam radiation to form a flame retardant material; the radiation dose is 20 kGy; the electron beam energy is 200 keV; and the curing temperature is 20°C.

[0059] Embodiment 2:

[0060] Step S1, condensation reaction of phenol and catechol: phenol and catechol are added into a reactor to carry out a condensation reaction; after the reaction, the heavy fraction is collected by vacuum distillation, washed and dried to prepare product A; the condensation reaction time is 5 hours, the condensation reaction temperature is 110°C; the condensation reaction solvent is a mixed solution of toluene and ethanol, the volume ratio of toluene to ethanol is 2:1.1; the molar ratio of phenol to catechol is 1:1.1; the condensation reaction catalyst is p-toluenesulfonic acid, and the condensation reaction pH value is 4.5;

[0061] Step S2, sulfonation reaction: product A and sulfuric acid are added to a reactor in a mass ratio of 1:1.2 to carry out a sulfonation reaction. After the reaction is completed, the sulfonation reaction liquid is poured into an ice-water mixture to precipitate, the precipitate is collected by filtration, and the product B is obtained by washing and drying; the sulfonation reaction temperature is 90° C., the sulfonation reaction time is 4 hours; the mass concentration of sulfuric acid is 20%; the drying temperature is 70° C.; the mass ratio of the sulfonation reaction liquid to the ice-water mixture is 1:5;

[0062] Step S3, zinc oxide treatment: uniformly mixing product B and zinc oxide to prepare mixture C; the mass ratio of product B to zinc oxide is 1:0.04;

[0063] Step S4, aminated aluminum hydroxide: dissolving a titanate coupling agent in anhydrous ethanol to prepare a titanate solution; mixing water and aluminum hydroxide, adjusting the pH to 5.0, to prepare a suspension, wherein the mass ratio of water to aluminum hydroxide is 2:1; adding the titanate solution to the suspension, performing an amination reaction, and forming a reaction solution D; the mass ratio of titanate to aluminum hydroxide is 0.03:1; the amination reaction temperature is 62°C, and stirring is continued for 1.5 hours; heating to 83°C, and stirring is continued for 1.5 hours;

[0064] Step S5, boron carbide and bismuth oxide treatment: adding boron carbide and bismuth oxide nanoparticles to the reaction solution D; the mass ratio of aluminum hydroxide to boron carbide and bismuth oxide in the reaction solution D is 1:0.009:0.012; collecting the precipitate by centrifugation to prepare a mixture E;

[0065] Step S6, particle size control of mixture F: the particle size of mixture E is controlled to be 30 nm by grinding to prepare mixture F;

[0066] Step S7, condensation reaction of mixture C and 2-hydroxyethyl isocyanurate: mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde are added to a reactor to carry out a condensation reaction; heavy fractions are collected by vacuum distillation, and the product G is obtained by recrystallization and drying through ethanol; the condensation reaction time is 5 hours, and the condensation reaction temperature is 90° C. The condensation reaction solvent is a mixed solution of dioxane and water, and the volume ratio of dioxane to water is 1:1.1; the mass ratio of mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde is 1:0.9:0.4:1.5; the condensation reaction catalyst is sodium hydroxide, and the condensation reaction pH value is 8.5;

[0067] Step S8, epoxy resin synthesis: dissolve product G in epichlorohydrin, add tetramethylammonium chloride, and drop a 50% sodium hydroxide aqueous solution in a mass ratio to carry out a pre-reaction at a temperature of 50° C. for 2.5 hours; then carry out a ring-opening reaction of epichlorohydrin at a temperature of 80° C. for 4.5 hours; the mass ratio of product G to epichlorohydrin is 1:5; the mass ratio of product G to tetramethylammonium chloride is 1:0.03; the mass ratio of product G to 50% sodium hydroxide aqueous solution is 1:4; cool to 25° C. to terminate the reaction; add deionized water for washing, collect the organic phase; remove the solvent by reduced pressure distillation to obtain product H.

[0068] Step S9, copper stearate treatment: adding copper stearate to ammonium nitrate and dispersing evenly to prepare a mixture I; the mass ratio of ammonium nitrate to copper stearate is 1:0.07;

[0069] Step S10, ammonium nitrate treatment: adding mixture I to product H, mixing evenly, to prepare mixture J; the mass ratio of product H to mixture I is 1:0.5;

[0070] Step S11, adding triphenylphosphine oxide: adding triphenylphosphine oxide to mixture J, mixing evenly, to prepare mixture K; the mass ratio of mixture J to triphenylphosphine oxide is 1:0.03;

[0071] Step S12, electrostatic spinning: dissolving the mixture K in a mixture of ethanol and acetone, and performing electrostatic spinning to prepare fiber L; the volume ratio of ethanol to acetone in the mixture of ethanol and acetone is 3:1; the electrostatic spinning voltage is 20 kV; the receiving distance is 20 cm; the temperature is 22° C.; the mass ratio of the mixture K to the mixture is 1:4; the diameter of the fiber L is 20 μm; the fiber L is dried to prepare the fiber M; the drying time is 2.5 hours; the drying temperature is 65° C.;

[0072] Step S13, electron beam radiation curing: the fiber M is cured by electron beam radiation to form a flame retardant material; the radiation dose is 25 kGy; the electron beam energy is 250 keV; and the curing temperature is 25°C.

[0073] Embodiment 3:

[0074] Step S1, condensation reaction of phenol and catechol: phenol and catechol are added into a reaction kettle to carry out condensation reaction; heavy fractions are collected by vacuum distillation, washed and dried to prepare product A; the condensation reaction time is 6 hours, the condensation reaction temperature is 120°C; the condensation reaction solvent is a mixed solution of toluene and ethanol, the volume ratio of toluene to ethanol is 2:1.2; the molar ratio of phenol to catechol is 1:1.2; the condensation reaction catalyst is p-toluenesulfonic acid, and the condensation reaction pH value is 5;

[0075] Step S2, sulfonation reaction: product A and sulfuric acid are added to a reactor at a mass ratio of 1:1.5 to carry out a sulfonation reaction. After the reaction is completed, the sulfonation reaction liquid is poured into an ice-water mixture to precipitate, the precipitate is collected by filtration, and the product B is obtained by washing and drying; the sulfonation reaction temperature is 100° C., the sulfonation reaction time is 5 hours; the mass concentration of sulfuric acid is 20%; the drying temperature is 80° C.; the mass ratio of the sulfonation reaction liquid to the ice-water mixture is 1:5;

[0076] Step S3, zinc oxide treatment: product B and zinc oxide are uniformly mixed in a mass ratio of 1:0.05 to prepare a mixture C;

[0077] Step S4, aminated aluminum hydroxide: dissolving a titanate coupling agent in anhydrous ethanol to prepare a titanate solution; mixing water and aluminum hydroxide, adjusting the pH to 5.5, to prepare a suspension, wherein the mass ratio of water to aluminum hydroxide is 2:1; adding the titanate solution to the suspension, performing an amination reaction, and forming a reaction solution D; the mass ratio of titanate to aluminum hydroxide is 0.04:1; the amination reaction temperature is 65°C, and stirring is continued for 2 hours; heating to 85°C, and stirring is continued for 2 hours;

[0078] Step S5, boron carbide and bismuth oxide treatment: adding boron carbide and bismuth oxide nanoparticles to the reaction solution D; the mass ratio of aluminum hydroxide to boron carbide and bismuth oxide in the reaction solution D is 1:0.01:0.015; collecting the precipitate by centrifugation to prepare a mixture E;

[0079] Step S6, particle size control of mixture F: the particle size of mixture E is controlled to be 40 nm by grinding to prepare mixture F;

[0080] Step S7, condensation reaction of mixture C and 2-hydroxyethyl isocyanurate: mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde are added to a reaction kettle to carry out a condensation reaction; heavy fractions are collected by vacuum distillation, and the product G is obtained by recrystallization with ethanol and drying; the condensation reaction time is 6 hours, and the condensation reaction temperature is 100° C.; the condensation reaction solvent is a mixture of dioxane and water, and the volume ratio of dioxane to water is 1:1.2; the mass ratio of mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde is 1:1.0:0.5:1.6; the condensation reaction catalyst is sodium hydroxide, and the condensation reaction is at a pH of 8 to 9;

[0081] Step S8, epoxy resin synthesis: dissolve product G in epichlorohydrin, add tetramethylammonium chloride, and drop a 50% sodium hydroxide aqueous solution in a mass ratio to carry out a pre-reaction at a temperature of 55° C. for 3 hours; then carry out a ring-opening reaction of epichlorohydrin at a temperature of 85° C. for 5 hours; the mass ratio of product G to epichlorohydrin is 1:6; the mass ratio of product G to tetramethylammonium chloride is 1:0.04; the mass ratio of product G to 50% sodium hydroxide aqueous solution is 1:5; cool to 30° C. to terminate the reaction; add deionized water for washing, collect the organic phase; remove the solvent by reduced pressure distillation to obtain product H.

[0082] Step S9, copper stearate treatment: adding copper stearate to ammonium nitrate and dispersing the mixture evenly to prepare a mixture I; the mass ratio of ammonium nitrate to copper stearate is 1:0.1;

[0083] Step S10, ammonium nitrate treatment: adding mixture I to product H, mixing evenly, to prepare mixture J; the mass ratio of product H to mixture I is 1:0.7;

[0084] Step S11, adding triphenylphosphine oxide: adding triphenylphosphine oxide to mixture J, mixing evenly, to prepare mixture K; the mass ratio of mixture J to triphenylphosphine oxide is 1:0.04;

[0085] Step S12, electrostatic spinning: dissolving the mixture K in an ethanol / acetone mixed solution, and performing electrostatic spinning to prepare a fiber L; the volume ratio of ethanol to acetone in the ethanol / acetone mixed solution is 3:1; the electrostatic spinning voltage is 25 kV; the receiving distance is 25 cm; the temperature is 25°C; the mass ratio of the mixture K to the mixed solution is 1:5; the diameter of the fiber L is 30 microns; the fiber L is dried to prepare the fiber M; the drying time is 3 hours; the drying temperature is 70°C;

[0086] Step S13, radiation curing: the fiber M is cured by radiation to form a flame retardant material; the radiation dose is 30 kGy; the electron beam energy is 300 keV; the curing temperature is 30° C.; and the curing time is 1 hour.

[0087] Example 4 investigates the effect of the curing method on the curing uniformity of the flame retardant material.

[0088] In step S13, heating is used instead of electron beam radiation curing, the curing temperature is 120° C., and the curing time is 1 hour. The other steps are consistent with those in Example 2.

[0089] According to GB / T 9274-2008 "Test Method for Determination of Curing Degree of Epoxy Resin", the curing rates of the flame retardant materials prepared in Example 2 and Example 4 were tested. Six samples were taken from each example and tested respectively. The mean and standard deviation were calculated. The RSD value was obtained by dividing the standard deviation by the mean to evaluate the uniformity of curing. The lower the RSD value, the higher the uniformity.

[0090] The test results are shown in the table below. Example 2 uses radiation curing, and Example 4 uses heat curing. The curing rate and uniformity of radiation curing are higher than those of heat curing. High-energy electrons have strong penetrability, ensuring that the coating is cured synchronously inside and outside, avoiding over-curing of the surface layer and under-curing of the inner layer caused by heat curing, thereby improving the internal uniformity of the flame retardant material.

[0091] Table 1 Comparison of the curing rate measurement results of Example 2 and Example 4 (unit: %)

[0092] Classification Example 2 Example 4 First measurement 99.2 90.7 Second measurement 99.0 99.1 The third measurement 99.1 91.4 The fourth measurement 99.0 96.3 The fifth measurement 99.5 95.6 The 6th measurement 99.3 97.5 Mean 99.2 94.9 Standard Deviation 0.2 3.7 RSD value 0.2 3.9

[0093] Example 5: Investigate the effect of copper stearate treatment on the uniformity of flame retardant properties of flame retardant materials.

[0094] The copper stearate treatment in step S9 was not performed, and the other steps were consistent with those in Example 2.

[0095] Example 6: investigates the effect of amino modification on the uniformity of flame retardant properties of flame retardant materials.

[0096] The aluminum hydroxide modified by amino in step S4 was not carried out, and aluminum hydroxide not modified by amino was directly used. The other steps were consistent with those in Example 5.

[0097] The limiting oxygen index of the flame retardant materials prepared in Example 2, Example 5 and Example 6 was measured according to GB / T2406.2-2009. The higher the limiting oxygen index, the higher the flame retardancy. Each example was sampled 6 times, measured separately, and the mean and standard deviation were calculated. The RSD value of the standard deviation divided by the mean was used to evaluate the uniformity of the flame retardant performance. The lower the RSD value, the higher the uniformity.

[0098] The test results are shown in the table below. Through copper stearate treatment, the uniformity of flame retardant performance of Example 2 is higher than that of Example 5; through amino modification of aluminum hydroxide, the uniformity of flame retardant performance of Example 5 is higher than that of Example 6.

[0099] Copper stearate is a metal soap compound, and its molecular structure contains a long hydrophobic chain (stearic acid group) and a hydrophilic metal ion (Cu 2+ ). The hydrophobic chain of copper stearate can be adsorbed on the surface of ammonium nitrate particles to form a physical barrier, reduce the van der Waals force between particles, and inhibit the agglomeration of ammonium nitrate particles. The surface activity of copper stearate can improve the compatibility of ammonium nitrate with the polymer matrix and promote the uniform distribution of ammonium nitrate in product H. Copper stearate also has lubricating properties, which can reduce the viscosity of the material, improve the shear efficiency of the mixing process, and indirectly help the ammonium nitrate to be more evenly dispersed in the subsequent steps. The above effects can improve the uniformity of the dispersion of ammonium nitrate, thereby improving the uniformity of flame retardant properties.

[0100] The surface of aluminum hydroxide modified by amino group enhances its interfacial bonding with the polymer matrix, reduces particle agglomeration, and makes aluminum hydroxide evenly dispersed. Aluminum hydroxide combines with isocyanate through amino group, thereby curing in the flame retardant material, and the bonding is relatively strong. Unmodified aluminum hydroxide exists in the flame retardant material in the form of coating, and the bonding with the flame retardant material is relatively loose. When the flame coating material is heated at the burning place, the particles of aluminum hydroxide will be heated to release vapor and become metal oxide to prevent heat conduction. The evenly dispersed aluminum hydroxide can stably release endothermic decomposition products (Al 2 O 3 and H 2 O), inhibiting the spread of flame and significantly improving the uniformity of flame retardant materials.

[0101] Table 2 Comparison of limiting oxygen index determination results of Example 2, Example 5 and Example 6 (unit: %)

[0102] Classification Example 2 Example 5 Example 6 First measurement 45 42 32 Second measurement 44 45 45 The third measurement 45 42 38 The fourth measurement 46 41 41 The fifth measurement 43 45 31 The 6th measurement 45 40 42 Mean 44.7 42.5 38.2 Standard Deviation 1.0 2.1 5.6 RSD value 2.3 4.9 14.8

[0103] Example 7: Investigate the effect of ammonium nitrate treatment on the limiting oxygen index of flame retardant materials.

[0104] The ammonium nitrate treatment in step S10 was not performed, and the other steps were consistent with those in Example 2.

[0105] Example 8: Investigate the effect of 2-hydroxyethyl isocyanurate on the limiting oxygen index of flame retardant materials.

[0106] In step S7, 2-hydroxyethyl isocyanurate is replaced with pentaerythritol, and the other steps are consistent with Example 7.

[0107] Pentaerythritol contains four hydroxyl groups (-OH), which can replace the hydroxyl function of 2-hydroxyethyl isocyanurate and condense with the active groups (such as carboxylic acid and epoxy groups) in mixture C to form a cross-linked network. Pentaerythritol does not contain nitrogen and will not generate nitrogen or nitrogen oxides during the subsequent heating process.

[0108] Example 9: Investigate the effect of boron carbide and bismuth oxide treatment on the limiting oxygen index of flame retardant materials.

[0109] The boron carbide and bismuth oxide treatment in step S5 was not performed, and the other steps were consistent with Example 8.

[0110] Example 10: Investigate the effect of zinc oxide treatment on the limiting oxygen index of flame retardant materials.

[0111] The zinc oxide treatment in step S3 was not performed, and the other steps were consistent with Example 9.

[0112] Example 11: Investigate the effect of sulfonation reaction on the limiting oxygen index of flame retardant materials.

[0113] The sulfonation reaction of step S2 was not performed, and the other steps were consistent with Example 10.

[0114] The limiting oxygen index of the flame retardant materials prepared in Examples 1 to 3 and Examples 7 to 12 was measured according to GB / T2406.2-2009. The higher the limiting oxygen index, the higher the flame retardancy.

[0115] According to the combustion test of GB / T 20284-2006, the amount of sulfur dioxide released by the flame retardant materials prepared in Example 9 and Example 10 was measured. The lower the sulfur dioxide concentration, the higher the sulfur dioxide absorption capacity.

[0116] The test results are shown in the table below.

[0117] By treating with ammonium nitrate, the flame retardant performance of Example 2 is higher than that of Example 7. Ammonium nitrate decomposes at high temperature to form nitrogen, water, and nitrogen-containing oxides, which prevent combustion, improve the flame retardant performance of the flame retardant, and improve the limiting oxygen index. At the same time, aluminum hydroxide decomposes at high temperature to form water. The formed water, on the one hand, prevents combustion and improves the flame retardant performance of the flame retardant. On the other hand, water reacts with nitrogen oxides and oxygen at high temperature to form nitric acid, which accelerates the oxidative decomposition of the polymer, prevents the propagation of the combustion flame, and improves the flame retardant performance. The decomposition temperatures of ammonium nitrate and aluminum hydroxide are relatively close. The present invention utilizes the above principle and selects to add ammonium nitrate and aluminum hydroxide to the flame retardant material to achieve a synergistic flame retardant effect.

[0118] By adding 2-hydroxyethyl isocyanurate, the flame retardant performance of Example 7 is higher than that of Example 8. The main products of the high-temperature decomposition of 2-hydroxyethyl isocyanurate include carbon dioxide, ammonia, etc. The generated carbon dioxide, ammonia and other flame-retardant gases form a foam structure on the side of the flame-retardant material facing the flame. Because the foam structure contains phenols and aromatic compounds, it has high thermal stability, which inhibits the foam from bursting at high temperatures. Oxygen and heat are shielded by the foam layer, thereby improving the flame retardant effect. Furthermore, when the foam structure is destroyed, the carbon dioxide, ammonia and other flame-retardant gases in the foam overflow, further inhibiting combustion and exerting a flame retardant function.

[0119] By treating with boron carbide and bismuth oxide, the flame retardant performance of Example 8 is higher than that of Example 9, and it can also have a radiation protection effect. Boron carbide and bismuth oxide can still remain chemically inert at high temperatures, forming a physical barrier to isolate oxygen from the combustible matrix and inhibit the spread of flames. Therefore, boron carbide and bismuth oxide can improve flame retardant properties. Boron carbide and bismuth oxide also have radiation protection functions. Boron carbide absorbs neutrons, while bismuth oxide relies on gamma-ray shielding, and the two complement each other to play a radiation protection function.

[0120] Through zinc oxide treatment, the flame retardant performance of Example 9 is higher than that of Example 10, and the sulfur dioxide release concentration of Example 9 is lower than that of Example 10. Zinc oxide, as an inert filler, can improve the thermal stability of the material and delay the starting temperature of thermal decomposition of the matrix.

[0121] The sulfonation reaction product can decompose at high temperature to generate the following toxic gas sulfur dioxide. Zinc oxide fixes sulfur dioxide through acid-base neutralization reaction and chemical adsorption, and the formed zinc sulfate is stable and non-toxic.

[0122] Through the sulfonation reaction, the flame retardant performance of Example 10 is higher than that of Example 11. The sulfonic acid group (-SO 3 H) can catalyze the dehydration and crosslinking of polymers at high temperatures, accelerating the carbonization reaction. The dense carbon layer formed covers the surface of the material, effectively isolating oxygen and heat transfer, and inhibiting the spread of flames. The decomposition of sulfonic acid groups requires the absorption of a large amount of heat (endothermic reaction), which reduces the surface temperature of the material and slows down the heat release rate. The sulfur oxides (such as SO 2 ) and water, dilute the concentration of combustible gas, reduce the oxygen partial pressure, and inhibit the combustion chain reaction. At the same time, some sulfur oxides can combine with zinc ions to form zinc sulfate, further stabilizing the carbon layer structure. Therefore, the sulfonation reaction can significantly improve the flame retardant properties of flame retardant materials.

[0123] Table 3 Limiting oxygen index measurement results of Examples 1-3 and 7-12

[0124]

[0125]

[0126] Table 4 Results of sulfur dioxide release concentration measurement in Example 9 and Example 10

[0127]

[0128] Example 12: Investigate the effect of the particle size of the mixture F on the transparency of the flame retardant material.

[0129] In step S6, the particle size of the mixture F is controlled to be 200 nm, and the other steps are consistent with those in Example 2.

[0130] The light transmittance of the flame retardant materials prepared in Example 2 and Example 12 was measured according to GB / T 2410-2008.

[0131] The test results are shown in the table below.

[0132] By controlling the particle size of the mixture F, the transmittance of Example 2 is higher than that of Example 12. When the particle diameter is smaller than the wavelength of the incident visible light (visible light is 400-700nm), the effect on the light scattering intensity is relatively small. The mixture F contains boron carbide, bismuth oxide, and aluminum hydroxide particles, which have a scattering effect on visible light. When the particle size of the mixture F is 20-40nm, it is in the transition zone between Rayleigh scattering and Mie scattering, which significantly reduces the effect on light scattering and improves the transmittance.

[0133] Table 5 Transmittance measurement results of Example 2 and Example 12 (unit: %)

[0134] Classification Processing conditions Light transmittance (%) Example 2 Particle size: 20nm 31 Example 12 Particle size: 200nm 6 .

Claims

1. A method for preparing a flame retardant material, characterized in that: The following steps are involved: Step S1, condensation reaction of phenol and catechol: adding phenol and catechol into a reaction kettle to carry out a condensation reaction; distilling the reaction liquid under reduced pressure, collecting the heavy fraction, washing and drying, and preparing product A; Step S2, sulfonation reaction: adding product A and sulfuric acid into a reactor to carry out sulfonation reaction, and after the reaction is completed, pouring the sulfonation reaction solution into an ice-water mixture to precipitate, collecting the precipitate by filtration, washing and drying to obtain product B; Step S3, zinc oxide treatment: uniformly mixing the product B with zinc oxide to prepare a mixture C; Step S4, aminated aluminum hydroxide: dissolving a titanate coupling agent in ethanol to prepare a titanate solution; mixing water and aluminum hydroxide to prepare a suspension; adding the titanate solution to the suspension to perform an aminated reaction to form a reaction solution D; Step S5, boron carbide and bismuth oxide treatment: adding boron carbide and bismuth oxide nanoparticles to the reaction solution D; collecting the precipitate by centrifugation to prepare a mixture E; Step S6, particle size control: grinding the mixture E to a particle size of 20 nm to 40 nm to prepare a mixture F; Step S7, condensation reaction of mixture C and 2-hydroxyethyl isocyanurate: adding mixture C, 2-hydroxyethyl isocyanurate, mixture F and paraformaldehyde into a reaction kettle to carry out condensation reaction; collecting heavy fractions by vacuum distillation, recrystallizing with ethanol and drying to obtain product G; Step S8, epoxy resin synthesis: dissolving product G in epichlorohydrin, adding tetramethylammonium chloride, and dropping sodium hydroxide aqueous solution to perform a preliminary reaction; then performing a ring-opening reaction of epichlorohydrin; then cooling to 20°C to 30°C to terminate the reaction; adding deionized water to the reaction solution for washing, collecting the organic phase; and removing the solvent by distillation under reduced pressure to obtain product H; Step S9, treating ammonium nitrate with copper stearate: adding copper stearate to ammonium nitrate and dispersing the mixture evenly to prepare a mixture I; Step S10, ammonium nitrate treatment: adding mixture I to product H, mixing evenly, to prepare mixture J; Step S11, adding triphenylphosphine oxide: adding triphenylphosphine oxide to mixture J, mixing evenly, to prepare mixture K; Step S12, electrospinning: dissolving the mixture K in a mixture of ethanol and acetone, and electrospinning to form a fiber L; the fiber L is dried to form a fiber M; Step S13, electron beam radiation curing: the fiber M is cured by electron beam radiation to form a flame retardant material.

2. The preparation method according to claim 1, characterized in that: The condensation reaction time of step S1 is 4 hours to 6 hours, and the condensation reaction temperature is 100°C to 120°C; the condensation reaction solvent is a mixed solution of toluene and ethanol, and the volume ratio of toluene to ethanol is 2:(1-1.2); the molar ratio of phenol to catechol is 1:(1-1.2); the condensation reaction catalyst is p-toluenesulfonic acid, and the condensation reaction pH value is 4-5.

3. The preparation method according to claim 2, characterized in that: The mass ratio of product A to sulfuric acid in step S2 is 1:(1.0-1.5); the sulfonation reaction temperature is 80°C-100°C, and the sulfonation reaction time is 3 hours-5 hours; the sulfuric acid mass concentration is 20%; the drying temperature is 60°C-80°C; and the mass ratio of the sulfonation reaction liquid to the ice-water mixture is 1:

5.

4. The preparation method according to claim 3, characterized in that: The mass ratio of product B to zinc oxide in step S3 is 1:(0.02-0.05).

5. The preparation method according to claim 4, characterized in that: In the step S4, the mass ratio of water to aluminum hydroxide is 2:1; the mass ratio of titanate to aluminum hydroxide is (0.02-0.04):1; the temperature of the first stage of the amination reaction is 60°C-65°C, and the time of the first stage of the amination reaction is 1 hour-2 hours; the temperature of the second stage of the amination reaction is 80°C-85°C, and the time of the second stage of the amination reaction is 1 hour-2 hours.

6. The preparation method according to claim 5, characterized in that: The mass ratio of aluminum hydroxide to boron carbide and bismuth oxide in the reaction solution D of step S5 is 1:(0.008-0.01):(0.01-0.015).

7. The preparation method according to claim 6, characterized in that: In step S7, the condensation reaction time is 4 hours to 6 hours, and the condensation reaction temperature is 80° C. to 100° C.; the condensation reaction solvent is a mixture of dioxane and water, and the volume ratio of dioxane to water is 1:(1-1.2); the mass ratio of mixture C, 2-hydroxyethyl isocyanurate, mixture F, and paraformaldehyde is 1:(0.8-1.0):(0.3-0.5):(1.4-1.6); the condensation reaction catalyst is sodium hydroxide, and the condensation reaction pH value is 8-9.

8. The preparation method according to claim 7, characterized in that: In the step S8, the pre-reaction temperature is 45°C to 55°C, and the pre-reaction time is 2 hours to 3 hours; the ring-opening reaction temperature is 75°C to 85°C, and the ring-opening reaction time is 4 hours to 5 hours; the mass ratio of the product G to epichlorohydrin is 1:(4-6); the mass ratio of the product G to tetramethylammonium chloride is 1:(0.02-0.04); the mass ratio of the product G to the sodium hydroxide aqueous solution is 1:(3-5).

9. A flame retardant material, characterized in that: The flame retardant material is made by any method described in claims 1 to 8.

10. Use of the flame retardant material according to claim 9 in new energy vehicles.

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