A high molecular flame-retardant material and a preparation method thereof

Abstract

This invention discloses a polymeric flame-retardant material and its preparation method, relating to the field of polymeric materials technology. In preparing the polymeric flame-retardant material, epichlorohydrin is used as a bridging agent to graft 2-(diphenylphosphino)ethylamine onto luteolin to obtain modified luteolin; polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate are polymerized to obtain polyurethane; the polyurethane is reacted with methyl 4-aminocinnamate to obtain modified polyurethane; cerium dioxide is reacted sequentially with γ-glycidoxypropyltrimethoxysilane and 3-amino-1,2,4-triazole to obtain modified cerium dioxide; the modified polyurethane, modified luteolin, and modified cerium dioxide are mixed and kneaded to obtain the polymeric flame-retardant material. The polymeric flame-retardant material prepared by this invention exhibits superior flame retardancy and weather resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polymer flame retardant material and its preparation method. Background Technology

[0002] Polyurethane elastomers are a special type of polymer material, widely used in aerospace, automotive parts, mining, geology, and medical fields due to their superior properties such as high strength, high toughness, wear resistance, and corrosion resistance. However, pure polyurethane elastomers are flammable, with a limiting oxygen index of only about 20%. Furthermore, when burned, they decompose to produce numerous toxic gases, and the dense smoke emitted can impair visibility, interfering with search and rescue operations. On the other hand, long-term practical application has revealed that polyurethane elastomers undergo photo-aging degradation under light exposure (especially ultraviolet light), significantly reducing their durability. Ultraviolet light is the main cause of polyurethane elastomer aging; the energy of ultraviolet irradiation is sufficient to trigger the breakage of chemical bonds, leading to molecular chain breakage and material aging, resulting in surface powdering, cracking, yellowing, and other phenomena that affect the material's aesthetics and mechanical properties. This invention focuses on the flame retardancy and weather resistance of polyurethane elastomers. Through improvements to existing technologies, a polyurethane elastomer material with both excellent flame retardant and weather-resistant properties has been successfully prepared. Summary of the Invention

[0003] The purpose of this invention is to provide a polymer flame retardant material and its preparation method to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A polymer flame retardant material, wherein the polymer flame retardant material is prepared by mixing 80-90 parts of modified polyurethane, 6-7 parts of modified luteolin, and 3-4 parts of modified cerium dioxide, and then mixing them together.

[0006] The modified polyurethane is prepared by reacting polyurethane and methyl 4-aminocinnamate in a mass ratio of 1:(0.3~0.4).

[0007] The polyurethane is prepared by reacting polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate in a molar ratio of (9~11):(6~7):(5~6):(18~22);

[0008] The modified luteolin was prepared by reacting pre-modified luteolin and 2-(diphenylphosphino)ethylamine in a molar ratio of 1:4.

[0009] The pre-modified luteolin is prepared by reacting luteolin and epichlorohydrin in a molar ratio of 1:(12~14);

[0010] The modified cerium dioxide is prepared by reacting pre-modified cerium dioxide and 3-amino-1,2,4-triazole in a mass ratio of 1:(2~3);

[0011] The pre-modified cerium dioxide is prepared by reacting cerium dioxide and γ-glycidoxypropyltrimethoxysilane in a mass ratio of 1:(0.4~0.6).

[0012] A method for preparing a polymeric flame-retardant material, the method comprising the following preparation steps:

[0013] (1) Add pre-modified luteolin and 2-(diphenylphosphino)ethylamine to N,N-dimethylformamide at a molar ratio of 1:4, 16 to 20 times the mass of pre-modified luteolin. Stir and react at 50 to 60°C for 7 to 8 hours, and then vacuum dry at 70 to 80°C for 26 to 30 hours to obtain modified luteolin.

[0014] (2) Mix polyurethane and N,N-dimethylformamide at a mass ratio of 1:(6~8) until homogeneous, stir at 40~50℃ for 20~30 min, add 0.3~0.4 times the mass of polyurethane of methyl 4-aminocinnamate, add 0.02~0.03 times the mass of methyl 4-aminocinnamate of N,N-dicyclohexylcarbodiimide, continue stirring and react for 18~22 h, remove N,N-dimethylformamide by rotary evaporation under reduced pressure, wash with anhydrous ethanol 3~5 times, and vacuum dry at 70~80℃ for 16~20 h to obtain modified polyurethane;

[0015] (3) Pre-modified cerium dioxide, 3-amino-1,2,4-triazole and anhydrous ethanol are mixed evenly in a mass ratio of 1:(2~3):(30~40), stirred and reacted at 50~60℃ for 8~10h, filtered, washed with anhydrous ethanol 3~5 times, and vacuum dried at 60~70℃ for 16~20h to obtain modified cerium dioxide;

[0016] (4) Mix the modified polyurethane, modified luteolin, modified cerium dioxide and N,N-dimethylformamide evenly and stir at 70~80℃ for 20~30min. Dry in an oven to constant weight, place in a mixer and mix at 170~180℃ for 10~12min. Cool naturally to room temperature to obtain a polymer flame retardant material.

[0017] Further, the preparation method of the pre-modified luteolin in step (1) is as follows: luteolin and epichlorohydrin are mixed at a molar ratio of 1:(12~14), and tetrabutylammonium bromide is added at 0.04~0.06 times the mass of luteolin. The mixture is stirred and refluxed at 100~110℃ for 3~4h, cooled to room temperature, and sodium hydroxide aqueous solution at 5~6 times the mass of luteolin is added. The mixture is stirred and reacted for another 5~6h. The mixture is extracted with dichloromethane and deionized water, and the organic phase is taken and vacuum dried at 70~80℃ for 20~24h to obtain the pre-modified luteolin.

[0018] Furthermore, the chemical formula for the reaction of the modified luteolin in step (1) is:

[0019] ;

[0020] Where R is: .

[0021] Furthermore, the sodium hydroxide aqueous solution has a mass fraction of 30% to 40%.

[0022] Further, the preparation method of polyurethane in step (2) is as follows: polypropylene glycol is dehydrated in a vacuum drying oven at 110~120℃ for 2h, and dimethylolpropionic acid is dehydrated in a vacuum drying oven at 70~80℃ for 5~6h; the dehydrated polypropylene glycol, dimethylolpropionic acid and isophorone diisocyanate are mixed, and dibutyltin dilaurate is added at 0.005~0.007 times the mass of polypropylene glycol. Under nitrogen protection, the mixture is stirred and reacted at 80~90℃ for 2~3h, cooled to 60~70℃, 1,4-butanediol is added, and the mixture is stirred and reacted for 70~80min. After cooling to room temperature, the mixture is discharged to obtain polyurethane.

[0023] Furthermore, the molar ratio of polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate is (9~11):(6~7):(5~6):(18~22).

[0024] Furthermore, the polypropylene glycol is one or more of PPG800, PPG1000, PPG1500, and PPG2000.

[0025] Further, the preparation method of the pre-modified cerium dioxide in step (3) is as follows: Cerium dioxide, anhydrous ethanol, and deionized water are mixed evenly in a mass ratio of 1:(26~30):(2~3), and ultrasonicated in an ultrasonic instrument for 30~40 min. γ-glycidyl etheroxypropyltrimethoxysilane with a mass of 0.4~0.6 times that of cerium dioxide is added, and the mixture is stirred and reacted at 60~70℃ for 2~3 h. After filtration, the mixture is washed 3~5 times with anhydrous ethanol and vacuum dried at 60~70℃ for 10~12 h to obtain the pre-modified cerium dioxide.

[0026] Furthermore, the particle size of the cerium dioxide is 20~500nm.

[0027] Furthermore, the dosage relationship of the modified polyurethane, modified luteolin, modified cerium dioxide, and N,N-dimethylformamide in step (4) is as follows: by mass parts, 80-90 parts of modified polyurethane, 6-7 parts of modified luteolin, 3-4 parts of modified cerium dioxide, and 160-200 parts of N,N-dimethylformamide.

[0028] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0029] First, a pre-modified luteolin is prepared by reacting luteolin with epichlorohydrin, and an epoxy group is attached to the luteolin. Then, the epoxy group on the pre-modified luteolin is reacted with the amino group on 2-(diphenylphosphino)ethylamine to prepare modified luteolin. Diphenylphosphine is attached to the luteolin. Luteolin is a natural flavonoid compound that is widely found in plants. Existing research shows that the unique structure of luteolin can promote char formation and increase the char residue after combustion, thus having an assisting flame retardant effect. In this application, epichlorohydrin is used as a bridging agent to graft diphenylphosphine onto luteolin, forming a phosphorus-luteolin composite flame retardant system, which gives the material a good flame retardant effect. In addition, luteolin can also absorb ultraviolet rays through keto-enol tautomerism, making it a natural ultraviolet protection material. The addition of luteolin can also improve the weather resistance of polymer materials.

[0030] Second, polyurethane is prepared by polymerizing polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate, resulting in polyurethane molecules with carboxylic acid groups on their side chains. The carboxylic acid groups on the side chains of the polyurethane molecules are then reacted with the amino groups on methyl 4-aminocinnamate to obtain modified polyurethane. Methyl cinnamate structures are grafted onto the side chains of the modified polyurethane molecules. Methyl cinnamate structures belong to the cinnamic acid class of ultraviolet absorbers. The conjugated system composed of benzene rings and double bonds can absorb ultraviolet energy, further improving the weather resistance of the polymer material.

[0031] Third, cerium dioxide was treated with γ-glycidyl etheroxypropyltrimethoxysilane to introduce a large number of epoxy groups onto the surface of cerium dioxide. Then, the epoxy groups on the cerium dioxide were reacted with the amino groups on 3-amino-1,2,4-triazole to prepare modified cerium dioxide, on which a large number of triazole structures were loaded. Cerium dioxide is an inorganic ultraviolet light shielding material, and existing research shows that it also has a synergistic flame retardant effect. Surface modification of cerium dioxide and loading a large number of triazole structures on it can not only improve the dispersion of cerium dioxide in polymer materials, but also form a cerium dioxide-triazole synergistic flame retardant system, further improving the flame retardancy and weather resistance of polymer materials. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] In the following examples and comparative examples, the polypropylene glycol used was PPG1000, manufactured by Artes; the cerium dioxide had a particle size of 100 nm and was manufactured by Suzhou Beike Nanotechnology Co., Ltd.

[0034] Example 1:

[0035] A method for preparing a polymer flame-retardant material, the method comprising the following preparation steps:

[0036] (1) Mix luteolin and epichlorohydrin at a molar ratio of 1:12, add 0.04 times the mass of luteolin in tetrabutylammonium bromide, stir and reflux at 100℃ for 4h, cool to room temperature, add 5 times the mass of luteolin in a 40% sodium hydroxide aqueous solution, continue stirring and reacting for 6h, extract with dichloromethane and deionized water, take the organic phase, and vacuum dry at 70℃ for 24h to obtain pre-modified luteolin; add pre-modified luteolin and 2-(diphenylphosphino)ethylamine at a molar ratio of 1:4 to 16 times the mass of pre-modified luteolin in N,N-dimethylformamide, stir and react at 50℃ for 8h, and vacuum dry at 70℃ for 30h to obtain modified luteolin;

[0037] (2) Weigh out polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate in a molar ratio of 9:6:5:18; dehydrate polypropylene glycol in a vacuum drying oven at 110°C for 2 hours, and dehydrate dimethylolpropionic acid in a vacuum drying oven at 70°C for 6 hours; mix the dehydrated polypropylene glycol, dimethylolpropionic acid, and isophorone diisocyanate, add dibutyltin dilaurate at 0.005 times the mass of polypropylene glycol, stir and react at 80°C for 3 hours under nitrogen protection, cool to 60°C, and add 1,4-butanediol. The mixture was stirred and reacted for another 80 minutes. After cooling to room temperature, the product was discharged to obtain polyurethane. Polyurethane and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:6 and stirred at 40°C for 30 minutes. 0.3 times the mass of polyurethane methyl 4-aminocinnamate and 0.02 times the mass of methyl 4-aminocinnamate N,N-dicyclohexylcarbodiimide were added. The mixture was stirred and reacted for another 22 hours. N,N-dimethylformamide was removed by rotary evaporation under reduced pressure. The mixture was washed three times with anhydrous ethanol and dried under vacuum at 80°C for 16 hours to obtain modified polyurethane.

[0038] (3) Cerium dioxide, anhydrous ethanol, and deionized water were mixed evenly in a mass ratio of 1:26:2 and placed in an ultrasonic instrument for sonication for 30 min. γ-glycidyl etheroxypropyltrimethoxysilane with a mass ratio of 0.4 times that of cerium dioxide was added, and the mixture was stirred at 60 °C for 3 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 60 °C for 12 h to obtain pre-modified cerium dioxide. Pre-modified cerium dioxide, 3-amino-1,2,4-triazole, and anhydrous ethanol were mixed evenly in a mass ratio of 1:2:30 and stirred at 50 °C for 10 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 60 °C for 20 h to obtain modified cerium dioxide.

[0039] (4) Weigh 80 parts of modified polyurethane, 6 parts of modified luteolin, 3 parts of modified cerium dioxide, and 160 parts of N,N-dimethylformamide by mass. Mix the modified polyurethane, modified luteolin, modified cerium dioxide, and N,N-dimethylformamide evenly and stir at 70°C for 30 min. Dry in an oven to constant weight, place in a mixer, and mix at 170°C for 12 min. Cool naturally to room temperature to obtain a polymer flame retardant material.

[0040] Example 2:

[0041] A method for preparing a polymer flame-retardant material, the method comprising the following preparation steps:

[0042] (1) Mix luteolin and epichlorohydrin at a molar ratio of 1:13, add 0.05 times the mass of luteolin in tetrabutylammonium bromide, stir and reflux at 105℃ for 3.5h, cool to room temperature, add 5.5 times the mass of luteolin in a 35% sodium hydroxide aqueous solution, continue stirring and reacting for 5.5h, extract with dichloromethane and deionized water, take the organic phase, and vacuum dry at 75℃ for 22h to obtain pre-modified luteolin; add pre-modified luteolin and 2-(diphenylphosphino)ethylamine at a molar ratio of 1:4 to 18 times the mass of pre-modified luteolin in N,N-dimethylformamide, stir and react at 55℃ for 7.5h, and vacuum dry at 75℃ for 28h to obtain modified luteolin;

[0043] (2) Weigh out polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate in a molar ratio of 10:6.5:5.5:20; dehydrate polypropylene glycol in a vacuum drying oven at 115°C for 2 hours, and dehydrate dimethylolpropionic acid in a vacuum drying oven at 75°C for 5.5 hours; mix the dehydrated polypropylene glycol, dimethylolpropionic acid, and isophorone diisocyanate, add dibutyltin dilaurate at 0.006 times the mass of polypropylene glycol, stir and react at 85°C for 2.5 hours under nitrogen protection, cool to 65°C, and add 1,4-butanediol. Butanediol was stirred for 75 minutes, and the mixture was cooled to room temperature before being discharged to obtain polyurethane. Polyurethane and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:7 and stirred at 45°C for 25 minutes. Methyl 4-aminocinnamate (0.35 times the mass of polyurethane) and N,N-dicyclohexylcarbodiimide (0.025 times the mass of methyl 4-aminocinnamate) were added. The mixture was stirred for 20 hours. N,N-dimethylformamide was removed by rotary evaporation under reduced pressure. The mixture was washed four times with anhydrous ethanol and dried under vacuum at 75°C for 18 hours to obtain modified polyurethane.

[0044] (3) Cerium dioxide, anhydrous ethanol, and deionized water were mixed evenly in a mass ratio of 1:28:2.5, and sonicated in an ultrasonic instrument for 35 min. γ-glycidyl etheroxypropyltrimethoxysilane was added at a mass ratio of 0.5 times that of cerium dioxide. The mixture was stirred at 65 °C for 2.5 h, filtered, washed 4 times with anhydrous ethanol, and vacuum dried at 65 °C for 11 h to obtain pre-modified cerium dioxide. Pre-modified cerium dioxide, 3-amino-1,2,4-triazole, and anhydrous ethanol were mixed evenly in a mass ratio of 1:2.5:35, stirred at 55 °C for 9 h, filtered, washed 4 times with anhydrous ethanol, and vacuum dried at 65 °C for 18 h to obtain modified cerium dioxide.

[0045] (4) Weigh 85 parts of modified polyurethane, 6.5 parts of modified luteolin, 3.5 parts of modified cerium dioxide, and 170 parts of N,N-dimethylformamide by mass. Mix the modified polyurethane, modified luteolin, modified cerium dioxide, and N,N-dimethylformamide evenly and stir at 75°C for 25 min. Dry in an oven to constant weight, place in a mixer, and mix at 175°C for 11 min. Cool naturally to room temperature to obtain a polymer flame retardant material.

[0046] Example 3:

[0047] A method for preparing a polymer flame-retardant material, the method comprising the following preparation steps:

[0048] (1) Mix luteolin and epichlorohydrin at a molar ratio of 1:14, add 0.06 times the mass of luteolin in tetrabutylammonium bromide, stir and reflux at 110℃ for 3h, cool to room temperature, add 6 times the mass of luteolin in a 30% sodium hydroxide aqueous solution, continue stirring and reacting for 5h, extract with dichloromethane and deionized water, take the organic phase, and vacuum dry at 80℃ for 20h to obtain pre-modified luteolin; add pre-modified luteolin and 2-(diphenylphosphino)ethylamine at a molar ratio of 1:4 to 20 times the mass of pre-modified luteolin in N,N-dimethylformamide, stir and react at 60℃ for 7h, and vacuum dry at 80℃ for 26h to obtain modified luteolin;

[0049] (2) Weigh out polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate in a molar ratio of 11:7:6:22; dehydrate polypropylene glycol in a vacuum drying oven at 120°C for 2 hours, and dehydrate dimethylolpropionic acid in a vacuum drying oven at 80°C for 5 hours; mix the dehydrated polypropylene glycol, dimethylolpropionic acid, and isophorone diisocyanate, add dibutyltin dilaurate at 0.007 times the mass of polypropylene glycol, stir and react at 90°C for 2 hours under nitrogen protection, cool to 70°C, and add 1,4-butanediol. The alcohol was stirred and reacted for 70 min. After cooling to room temperature, the product was discharged to obtain polyurethane. Polyurethane and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:8 and stirred at 50°C for 20 min. 0.4 times the mass of polyurethane methyl 4-aminocinnamate and 0.03 times the mass of methyl 4-aminocinnamate N,N-dicyclohexylcarbodiimide were added. The mixture was stirred and reacted for 18 h. N,N-dimethylformamide was removed by rotary evaporation under reduced pressure. The product was washed 5 times with anhydrous ethanol and dried under vacuum at 80°C for 16 h to obtain modified polyurethane.

[0050] (3) Cerium dioxide, anhydrous ethanol, and deionized water were mixed evenly in a mass ratio of 1:30:3, and ultrasonicated in an ultrasonic instrument for 40 min. γ-glycidyl etheroxypropyltrimethoxysilane with a mass ratio of 0.6 times that of cerium dioxide was added, and the mixture was stirred at 70 °C for 2 h. After filtration, the mixture was washed 5 times with anhydrous ethanol and dried under vacuum at 70 °C for 10 h to obtain pre-modified cerium dioxide. Pre-modified cerium dioxide, 3-amino-1,2,4-triazole, and anhydrous ethanol were mixed evenly in a mass ratio of 1:3:40, and stirred at 60 °C for 8 h. After filtration, the mixture was washed 5 times with anhydrous ethanol and dried under vacuum at 70 °C for 16 h to obtain modified cerium dioxide.

[0051] (4) Weigh 90 parts of modified polyurethane, 7 parts of modified luteolin, 4 parts of modified cerium dioxide, and 200 parts of N,N-dimethylformamide by mass. Mix the modified polyurethane, modified luteolin, modified cerium dioxide, and N,N-dimethylformamide evenly and stir at 80°C for 20 minutes. Dry in an oven to constant weight, place in a mixer, and mix at 180°C for 10 minutes. Cool naturally to room temperature to obtain a polymer flame retardant material.

[0052] Comparative Example 1:

[0053] The difference between the preparation method of the polymer flame retardant material in Comparative Example 1 and Example 2 is that step (1) is omitted, and step (4) is modified as follows: Weigh 85 parts of modified polyurethane, 6.5 parts of luteolin, 3.5 parts of modified cerium dioxide, and 170 parts of N,N-dimethylformamide by mass; mix the modified polyurethane, luteolin, modified cerium dioxide, and N,N-dimethylformamide evenly and stir at 75°C for 25 min, dry in an oven to constant weight, place in a mixer, and mix at 175°C for 11 min, then cool naturally to room temperature to obtain the polymer flame retardant material. The remaining steps are the same as in Example 2.

[0054] Comparative Example 2:

[0055] The preparation method of the polymer flame retardant material in Comparative Example 2 differs from that in Example 2 in that step (1) is omitted, and step (4) is modified as follows: Weigh 85 parts of modified polyurethane, 3.5 parts of modified cerium dioxide, and 170 parts of N,N-dimethylformamide by mass; mix the modified polyurethane, modified cerium dioxide, and N,N-dimethylformamide evenly and stir at 75°C for 25 min, dry in an oven to constant weight, place in a mixer, and mix at 175°C for 11 min, then cool naturally to room temperature to obtain the polymer flame retardant material. The remaining steps are the same as in Example 2.

[0056] Comparative Example 3:

[0057] The preparation method of the polymer flame retardant material in Comparative Example 3 differs from that in Example 2 only in step (2). Step (2) is modified as follows: Polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate are weighed in a molar ratio of 10:6.5:5.5:20; Polypropylene glycol is dehydrated in a vacuum drying oven at 115°C for 2 hours, and dimethylolpropionic acid is dehydrated in a vacuum drying oven at 75°C for 5.5 hours; The dehydrated polypropylene glycol, dimethylolpropionic acid, and isophorone diisocyanate are mixed, and dibutyltin dilaurate (0.006 times the mass of polypropylene glycol) is added. Under nitrogen protection, the mixture is stirred and reacted at 85°C for 2.5 hours. The temperature is lowered to 65°C, 1,4-butanediol is added, and the mixture is stirred and reacted for another 75 minutes. After cooling to room temperature, the mixture is discharged to obtain the modified polyurethane. The remaining steps are the same as in Example 2.

[0058] Comparative Example 4:

[0059] The preparation method of the polymer flame retardant material in Comparative Example 4 differs from that in Example 2 in that step (3) is omitted, and step (4) is modified as follows: 85 parts of modified polyurethane, 6.5 parts of modified luteolin, 3.5 parts of cerium dioxide, and 170 parts of N,N-dimethylformamide are weighed by mass. The modified polyurethane, modified luteolin, cerium dioxide, and N,N-dimethylformamide are mixed evenly and stirred at 75°C for 25 min. The mixture is then dried in an oven to constant weight, placed in a mixer, and kneaded at 175°C for 11 min. After natural cooling to room temperature, the polymer flame retardant material is obtained. The remaining steps are the same as in Example 2.

[0060] Test Example 1

[0061] Limiting oxygen index test

[0062] Testing instrument: HC-2 oxygen indexer; Reference standard: ASTM D2863; Sample size: 100 x 6.5 x 3 mm 3 Five samples were tested in each group of experiments. The results are shown in Table 1.

[0063] Table 1 - Limiting Oxygen Index Test

[0064] LOI value (%) LOI value (%) Example 1 33.98 Comparative Example 1 29.61 Example 2 34.64 Comparative Example 2 26.16 Example 3 34.17 Comparative Example 3 33.28 Comparative Example 4 29.34

[0065] As can be seen from the experimental data in Table 1, the LOI values ​​of Examples 1-3 are greater than those of Comparative Examples 1-2, and the LOI value of Comparative Example 1 is greater than that of Comparative Example 2. This is because the unique benzopyran ring structure in luteolin can promote char formation and increase the char residue rate after combustion, thus having an assisting flame retardant effect. In this application, epichlorohydrin is used as a bridging agent to graft diphenylphosphine onto luteolin, forming a phosphorus-luteolin composite flame retardant system, which gives the material a good flame retardant effect.

[0066] As can be seen from the experimental data in Table 1, the LOI values ​​of Examples 1-3 are greater than the LOI value of Comparative Example 4. This is because treating cerium dioxide with γ-glycidoxypropyltrimethoxysilane introduces a large number of epoxy groups onto the surface of cerium dioxide; then reacting the epoxy groups on cerium dioxide with the amino groups on 3-amino-1,2,4-triazole produces modified cerium dioxide, which loads a large number of triazole structures onto the surface of cerium dioxide; thus forming a cerium dioxide-triazole synergistic flame retardant system; further improving the flame retardant ability of the polymer material.

[0067] Test Example 2

[0068] Weather resistance test

[0069] Reference standard: GB / T 528-2009; Sample size: 50×3×4mm3 ; Tension rate: 500 mm / min.

[0070] Operating procedure: Test the tensile strength of the sample according to GB / T 528-2009, and record it as A; place the sample in a UV aging test chamber with a wavelength of 340nm and an intensity of 0.76W / m. 2 After 12 days of UV irradiation, the tensile strength was tested using the same method after the aging test, denoted as B. The weather resistance was expressed as B / A×100%. The test results are shown in Table 2.

[0071] Table 2 - Weather Resistance Test

[0072] B / A×100% B / A×100% Example 1 93.29% Comparative Example 1 91.23% Example 2 93.67% Comparative Example 2 84.74% Example 3 92.88% Comparative Example 3 79.51% Comparative Example 4 90.81%

[0073] Analysis of the experimental data in Table 2 reveals that the experimental data for Examples 1-3 are greater than those for Comparative Examples 2-3. This indicates that Examples 1-3 showed a smaller decrease in tensile strength after aging, while Comparative Examples 2-3 showed a larger decrease. This suggests that Examples 1-3 have better weather resistance than Comparative Examples 2-3. This is because Examples 1-3 contain luteolin, while Comparative Example 2 does not. Luteolin can absorb ultraviolet light through keto-enol tautomerism, making it a natural UV protection material. The addition of luteolin improves the weather resistance of the polymer material. Examples 1-3 grafted methyl cinnamate structures onto the polyurethane side chains, while Comparative Example 3 did not. Methyl cinnamate belongs to the cinnamic acid class of UV absorbers. The conjugated system composed of benzene rings and double bonds can absorb ultraviolet energy, further improving the weather resistance of the material.

[0074] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A polymer flame-retardant material, characterized in that, The polymer flame retardant material is prepared by mixing 80-90 parts of modified polyurethane, 6-7 parts of modified luteolin, 3-4 parts of modified cerium dioxide and 160-200 parts of N,N-dimethylformamide, drying and then mixing. The modified polyurethane is prepared by reacting polyurethane and methyl 4-aminocinnamate in a mass ratio of 1:(0.3~0.4). The polyurethane is prepared by reacting polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol, and isophorone diisocyanate in a molar ratio of (9~11):(6~7):(5~6):(18~22); The modified luteolin was prepared by reacting pre-modified luteolin and 2-(diphenylphosphino)ethylamine in a molar ratio of 1:

4. The pre-modified luteolin is prepared by reacting luteolin and epichlorohydrin in a molar ratio of 1:(12~14); The modified cerium dioxide is prepared by reacting pre-modified cerium dioxide and 3-amino-1,2,4-triazole in a mass ratio of 1:(2~3); The pre-modified cerium dioxide is prepared by reacting cerium dioxide and γ-glycidoxypropyltrimethoxysilane in a mass ratio of 1:(0.4~0.6).

2. A method for preparing a polymer flame-retardant material, characterized in that, The preparation method of the polymer flame retardant material includes the following preparation steps: (1) Premodified luteolin and 2-(diphenylphosphino)ethylamine were added to N,N-dimethylformamide at a molar ratio of 1:4, stirred and reacted at 50~60℃ for 7~8h, and then dried under vacuum to obtain modified luteolin. (2) Mix polyurethane and N,N-dimethylformamide evenly, stir at 40~50℃ for 20~30min, add 4-aminocinnamate methyl ester at 0.3~0.4 times the mass of polyurethane, add N,N-dicyclohexylcarbodiimide at 0.02~0.03 times the mass of 4-aminocinnamate methyl ester, continue stirring and reacting for 18~22h, remove N,N-dimethylformamide by rotary evaporation under reduced pressure, wash, and vacuum dry to obtain modified polyurethane; (3) Pre-modified cerium dioxide, 3-amino-1,2,4-triazole and anhydrous ethanol are mixed evenly in a mass ratio of 1:(2~3):(30~40), stirred and reacted at 50~60℃ for 8~10h, filtered, washed and vacuum dried to obtain modified cerium dioxide. (4) Mix the modified polyurethane, modified luteolin, modified cerium dioxide and N,N-dimethylformamide evenly, stir at 70~80℃ for 20~30min, dry in an oven to constant weight, place in a mixer, mix at 170~180℃ for 10~12min, and cool naturally to room temperature to obtain a polymer flame retardant material.

3. The method for preparing a polymer flame-retardant material as described in claim 2, characterized in that, The preparation method of the pre-modified luteolin in step (1) is as follows: luteolin and epichlorohydrin are mixed at a molar ratio of 1:(12~14), and tetrabutylammonium bromide is added at 0.04~0.06 times the mass of luteolin. The mixture is stirred and refluxed at 100~110℃ for 3~4h, cooled to room temperature, and sodium hydroxide aqueous solution at 5~6 times the mass of luteolin is added. The mixture is stirred and reacted for another 5~6h. The mixture is extracted with dichloromethane and deionized water, and the organic phase is collected and dried under vacuum to obtain the pre-modified luteolin.

4. The method for preparing a polymer flame-retardant material as described in claim 2, characterized in that, The chemical formula for the reaction of modified luteolin in step (1) is: ; Where R is: .

5. The method for preparing a polymer flame-retardant material as described in claim 3, characterized in that, The sodium hydroxide aqueous solution has a mass fraction of 30% to 40%.

6. The method for preparing a polymer flame-retardant material as described in claim 2, characterized in that, The polyurethane preparation method in step (2) is as follows: Polypropylene glycol is dehydrated in a vacuum drying oven at 110~120℃ for 2 hours, and dimethylolpropionic acid is dehydrated in a vacuum drying oven at 70~80℃ for 5~6 hours; the dehydrated polypropylene glycol, dimethylolpropionic acid and isophorone diisocyanate are mixed, and dibutyltin dilaurate is added at 0.005~0.007 times the mass of polypropylene glycol. Under nitrogen protection, the mixture is stirred and reacted at 80~90℃ for 2~3 hours, then cooled to 60~70℃, 1,4-butanediol is added, and the mixture is stirred and reacted for another 70~80 minutes. After cooling to room temperature, the mixture is discharged to obtain polyurethane.

7. The method for preparing a polymer flame-retardant material as described in claim 6, characterized in that, The molar ratio of polypropylene glycol, dimethylolpropionic acid, 1,4-butanediol and isophorone diisocyanate is (9~11):(6~7):(5~6):(18~22).

8. The method for preparing a polymer flame-retardant material as described in claim 6, characterized in that, The polypropylene glycol is one or more of PPG800, PPG1000, PPG1500, and PPG2000.

9. The method for preparing a polymer flame-retardant material as described in claim 2, characterized in that, The preparation method of the pre-modified cerium dioxide in step (3) is as follows: Cerium dioxide, anhydrous ethanol and deionized water are mixed evenly and placed in an ultrasonic instrument for ultrasonication for 30-40 min. γ-glycidyl etheroxypropyltrimethoxysilane with a mass of 0.4-0.6 times that of cerium dioxide is added. The mixture is stirred and reacted at 60-70℃ for 2-3 h. After filtration, washing and vacuum drying, the pre-modified cerium dioxide is obtained.

10. The method for preparing a polymer flame-retardant material as described in claim 2, characterized in that, The dosage relationship of modified polyurethane, modified luteolin, modified cerium dioxide, and N,N-dimethylformamide in step (4) is as follows: by mass parts, 80-90 parts of modified polyurethane, 6-7 parts of modified luteolin, 3-4 parts of modified cerium dioxide, and 160-200 parts of N,N-dimethylformamide.

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