A graft-modified anti-aging and flame-retardant polypropylene and its preparation method

Abstract

The present invention belongs to the technical field of flame-retardant polymers, and particularly relates to a graft-modified anti-aging flame-retardant polypropylene and a preparation method thereof. The graft-modified anti-aging flame-retardant polypropylene comprises the following raw materials in parts by mass: 100 parts of polyolefin, 4-7 parts of vinyl silane coupling agent, and 8-15 parts of a reactive flame retardant shown in formula (I). The present invention completes the modification of polypropylene by melt grafting by adding a self-made nitrogen-phosphorus synergistic reactive flame retardant and a vinyl silane coupling agent to polypropylene, significantly improving the flame retardancy of polypropylene, and the flame retardancy has excellent weather resistance. After long-term high temperature and high humidity aging of double 85, the flame retardant performance basically does not decrease. In addition to improving the weather resistance of the flame retardant performance, the nitrogen-phosphorus synergistic reactive flame retardant of the present invention also has the advantages of less addition amount and little influence on the mechanical properties of polyolefin.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame-retardant polymers, and particularly relates to a graft-modified anti-aging flame-retardant polypropylene and a preparation method thereof. Background Art

[0002] Polyolefins are currently widely used thermoplastic polymers, which have excellent properties such as non-toxicity, low density, and chemical corrosion resistance. However, polyolefins are flammable materials. For example, the LOI of polyethylene and polypropylene is only 17 - 18.5%. When burning, the heat release rate is high, and it is easy to produce molten drips. Therefore, it is necessary to carry out flame-retardant treatment on them.

[0003] Currently, the common method for flame-retardant treatment of polypropylene is physical blending. For example, a flame retardant and a polyolefin matrix are melt co-extruded together. The flame retardants include inorganic fillers and organic flame retardants. However, the method of improving the flame retardancy of polyolefins by physical blending has drawbacks: on the one hand, a large addition amount is required to achieve a suitable flame-retardant effect. For example, 20% of an intumescent flame retardant, or more than 40% of a metal hydroxide flame retardant is required, which increases the manufacturing cost and affects the mechanical properties of polyolefin materials. CN119505412A discloses a flame-retardant high-modulus polypropylene composite material, which comprises the following components in parts by weight: 50 - 60 parts of polypropylene, 30 - 40 parts of a phosphorus-nitrogen-based flame retardant, 3 - 5 parts of a compatibilizer, and 0.5 - 1.5 parts of a dispersant; the dispersant is an imidized isobutylene-maleic anhydride copolymer, and the compatibilizer is a polystyrene-oxazoline graft polymer. This patent uses a large amount of flame retardants and also requires a compatibilizer to improve the compatibility between the flame retardant and polyolefin. This method of improving flame retardancy by physical blending has the above-mentioned drawbacks.

[0004] Polyolefins are non-polar polymer materials with poor compatibility with conventional flame retardant systems. In a humid and hot environment, the physically blended flame retardants are prone to migration, precipitation, and failure, resulting in a decline in the flame retardant effect. This limits the application of polypropylene materials in fields that require flame retardancy and are under high-temperature conditions for a long time. For example, in the flame retardant modification of polyolefins, reactive flame retardants are added to chemically modify polypropylene to obtain polyolefins with excellent weather resistance. Polyolefins are prepared by using polyolefins and functional monomers through photo-initiation or thermal initiation. For example, CN119639163A discloses a method for preparing a flame retardant and anti-aging polyolefin plastic, which includes the following steps: S1. Add pretreated polypropylene, aqueous acrylic acid solution, and benzophenone solution to a glass reaction kettle, transfer it to an ultraviolet cross-linking instrument, and carry out ultraviolet grafting reaction, followed by post-treatment to obtain modified polypropylene; S2. Add [(6-oxo-6H-dibenzo[c,e][1,2]oxaphosphorin-6-yl)methyl]succinic acid, isophorone diisocyanate, triethylamine, and xylene to a reaction kettle and stir. Under nitrogen protection, raise the temperature of the reaction kettle to 40-60°C, keep the temperature for reaction for 2-3h, add 2-cyclopropylacetamide, and react for 10-12h, followed by post-treatment to obtain a flame retardant; S3. Add the modified polypropylene, modified anti-aging agent, flame retardant, and compound nucleating agent to a twin-screw extruder for melt extrusion, and inject it into a single-screw granulator to obtain a composite polypropylene plastic. This patent still needs to separately prepare a modified anti-aging agent and modified polypropylene and extrude them together in a twin-screw extruder, with a complicated preparation process and not suitable for industrial production.

[0005] CN119144080A discloses an intrinsic flame retardant and antioxidant cross-linked polyolefin composite material, and its raw materials are composed of the following parts by mass: 34-82 parts of polyolefin, 10-40 parts of flame retardant unit side-chain grafted polyethylene, 16-30 parts of halogen-free flame retardant, and 1-2.5 parts of cross-linking agent; the flame retardant unit side-chain grafted polyethylene is composed of EVA hydrolytically grafted with a flame retardant containing a flame retardant structural unit. The flame retardant containing a flame retardant structural unit is selected from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, diphenylphosphinous chloride, or anthracene formic acid. However, this patent still needs to add a halogen-free flame retardant to have the required flame retardant performance.

[0006] CN118599204A discloses a high-strength flame retardant and antistatic polyethylene polymer material, which includes the following components in parts by weight: 100 parts of ultra-high molecular weight polyethylene, 10-25 parts of carboxylated graphene, 3-15 parts of flame retardant and antistatic cross-linking agent, 4-8 parts of polyethylene grafted maleic anhydride, 0.8-1.5 parts of antioxidant, and 0.1-1 part of nucleating agent. The structural formula of the flame retardant and antistatic cross-linking agent is as follows:

[0007] 。 By using the hydroxyl and alkenyl groups on its surface to chemically crosslink with the carboxyl groups of polyethylene, polyethylene grafted maleic anhydride, and carboxylated graphene, a continuous crosslinked network structure is formed, resulting in a high-strength flame-retardant and antistatic polyethylene polymer material. However, the preparation process of the flame retardant used in this patent is complex, requiring three-step reactions to obtain the flame retardant, and the raw materials are expensive with a low yield, which is not suitable for large-scale industrial production. Summary of the Invention

[0008] To solve the existing technology. Specifically, the present invention provides the following technical solutions to solve the above technical problems:

[0009] A graft-modified anti-aging flame-retardant polypropylene, comprising the following raw materials in parts by mass: 100 parts of polyolefin, 4-7 parts of vinyl silane coupling agent, and 8-15 parts of a reactive flame retardant represented by formula (I):

[0010] (I).

[0011] Preferably, the graft-modified anti-aging flame-retardant polypropylene comprises the following raw materials in parts by mass: 100 parts of polyolefin, 4-7 parts of vinyl silane coupling agent, and 10-12 parts of a reactive flame retardant represented by formula (I)

[0012] The inventors' previous patent disclosed a nitrogen-phosphorus synergistic flame retardant represented by formula (I). Through the Atherton-Todd reaction of maleic hydrazide and DOPO, the coupling of DOPO and hydrazide compounds was achieved, obtaining a new type of nitrogen-phosphorus synergistic flame retardant. The inventors found that this flame retardant can endow PBT with excellent flame retardant effects at a relatively low addition amount, confirming that this flame retardant is a flame retardant with excellent performance. Since the flame retardant represented by formula (I) has polymerizable double bonds, it is expected to become a reactive flame retardant. In the present invention, the flame retardant represented by formula (I), polyolefin, and vinyl silane coupling agent are melt-grafted and modified together to obtain a polyolefin material with excellent flame retardant properties. Moreover, the obtained flame-retardant polyolefin has excellent flame retardant and anti-aging properties, and its flame retardant performance basically does not decrease after long-term aging in a humid and hot environment.

[0013] Furthermore, the polyolefin is selected from at least one of polyethylene and polypropylene, and the melt index of the polyolefin is 5-100 g / 10 min at 230 °C and 2.16 kg; and / or the vinyl silane coupling agent is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0014] Preferably, the melt index of the polyolefin is 5-10 g / 10 min at 230 °C and 2.16 kg.

[0015] Further, the graft-modified anti-aging flame-retardant polypropylene further comprises the following raw materials in parts by mass: 1-3 parts of a toughening agent, 0.1-1 part of an antioxidant, and 0.1-1 part of a lubricant.

[0016] The toughening agent is selected from at least one of ethylene-propylene-diene rubber; the antioxidant is selected from at least one of antioxidant 1076, antioxidant 168, antioxidant 1098, antioxidant 1010, and antioxidant BHT; the lubricant is selected from at least one of magnesium stearate, zinc stearate, and polyethylene wax.

[0017] Further, the reactive flame retardant represented by formula (I) is prepared by a preparation method including the following steps: maleic hydrazide and DOPO react in the presence of an acid-binding agent and a halogenating reagent, and then are post-treated; the synthesis route is as follows:

[0018] 。

[0019] Further, the acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and tetramethylguanidine; the halogenating reagent is carbon tetrachloride. Further, the molar ratio of maleic hydrazide, DOPO, the acid-binding agent, and the halogenating reagent is 1:2.1-2.5:50-100:50-100. The slight excess of DOPO and the far excess of the acid-binding agent and the halogenating reagent are both for the purpose of increasing the yield of the DOPO disubstituted product.

[0020] Further, the reaction solvent is a halogenated hydrocarbon, and the halogenated hydrocarbon is selected from at least one of dichloromethane and dichloroethane. The reaction conditions are to react at 50-80 °C for 5-15 h. After the reaction is completed, the solvent and the halogenating reagent are evaporated, and the remaining product is slurried and purified with ethanol to remove the salt formed by the acid-binding agent (such as triethylamine hydrochloride) and other impurities.

[0021] Further, in the reaction, while adding the acid-binding agent, a halogenated salt with a molar amount of 0.05-0.1 times that of maleic hydrazide is added, and the reaction solvent is a mixed solvent of a halogenated hydrocarbon and an alcohol with 1-3 carbon atoms in a volume ratio of 10:1-2. Preferably, the halogenated salt is selected from lithium chloride, zinc chloride, ferric trichloride, and aluminum trichloride.

[0022] There are two active N-H groups on maleic hydrazide that can react with DOPO. However, after one DOPO substitution occurs, since DOPO is a relatively large group, due to steric hindrance, the remaining N-H activity decreases, and the yield of the double-substituted DOPO product is affected. The inventors also found that the product of single DOPO substitution has an important impact on the performance of the flame retardant, and even a small amount of it will affect the flame retardant effect of the flame retardant. Therefore, it is necessary to increase the yield of the double DOPO product. The inventors unexpectedly found that when a small amount of halogenated salt is added during the reaction and the solvent is a mixture of halogenated hydrocarbon and lower alcohol, the yield of the double DOPO substitution product can be significantly increased. The inventors speculated that the possible reason is that the halogenated salt can accelerate the formation of acyl chloride in the first stage and react with the other substrate faster; in addition, it can also increase the nucleophilicity of hydroxylamine in acyl hydrazide, which helps to form the double-substituted product.

[0023] Furthermore, the present invention also provides a method for preparing the graft-modified anti-aging flame-retardant polypropylene as described above, comprising the following steps:

[0024] (S1) React maleic hydrazide and DOPO in the presence of an acid-binding agent and a halogenating agent to prepare the reactive flame retardant of formula (I);

[0025] (S2) Mix 100 parts by mass of polyolefin, 8-15 parts by mass of the reactive flame retardant of formula (I), 4-7 parts by mass of vinyl silane coupling agent, and 0.1-0.5 parts by mass of initiator evenly, add them to a twin-screw extruder, and melt-extrude and pelletize to obtain the graft-modified anti-aging flame-retardant polypropylene.

[0026] Furthermore, the initiator is selected from at least one of dicumyl peroxide, di-tert-butyl peroxide cumene, dicyclohexyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, and tert-butyl perpivalate.

[0027] Furthermore, in step (S2), the mixing method is a high-speed mixer; the process conditions for melt-extrusion and pelletization are 190-230 °C and a screw speed of 200-300 rpm.

[0028] Furthermore, in step (S2), when adding the reactive flame retardant of formula (I), 1-3 parts by mass of a toughening agent, 0.1-1 part by mass of an antioxidant, and 0.1-1 part by mass of a lubricant are also added.

[0029] Further, in step (S1), the acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and tetramethylguanidine; the halogenating reagent is carbon tetrachloride. Further still, the molar ratio of maleic hydrazide, DOPO, acid-binding agent, and halogenating reagent is 1:2.1-2.5:50-100:50-100. The slight excess of DOPO and the far excess of acid-binding agent and halogenating reagent are both for the purpose of increasing the yield of the DOPO double-substituted product.

[0030] Further, in step (S1), the reaction solvent is a halogenated hydrocarbon, and the halogenated hydrocarbon is selected from at least one of dichloromethane and dichloroethane. The reaction conditions are to react at 50-80 °C for 5-15 h. After the reaction is completed, the solvent and the halogenating reagent are distilled off, and the remaining product is slurried and purified with ethanol to remove the salt formed by the acid-binding agent (such as triethylamine hydrochloride) and other impurities.

[0031] Further, in step (S1), while adding the acid-binding agent, a halogenated salt in an amount 0.05-0.1 times the molar amount of maleic hydrazide is also added, and the reaction solvent is a mixed solvent of a halogenated hydrocarbon and an alcohol having 1-3 carbon atoms in a volume ratio of 10:1-2. Preferably, the halogenated salt is selected from lithium chloride, zinc chloride, ferric trichloride, and aluminum trichloride.

[0032] In the present invention, by adding a self-made nitrogen-phosphorus synergistic reactive flame retardant and a vinyl silane coupling agent to polypropylene and modifying the polypropylene by melt grafting, the flame retardancy of the polypropylene is significantly improved, and the flame retardancy has excellent weather resistance. After long-term high-temperature and high-humidity aging at double 85, the flame retardant performance basically does not decline. In addition to improving the weather resistance of the flame retardant performance, the nitrogen-phosphorus synergistic reactive flame retardant of the present invention also has the advantages of low addition amount and little influence on the mechanical properties of polyolefins. Description of the Drawings

[0033] Figure 1 is the 1 1H NMR spectrum of the product obtained in Preparation Example 1;

[0034] Figure 2 is the 31 31P NMR spectrum of the product obtained in Preparation Example 1;

[0035] Figure 3 is the mass spectrum of the product obtained in Preparation Example 1;

[0036] Figure 4 is the DSC chart of the product obtained in Preparation Example 1;

[0037] Figure 5 is the TGA chart of the product obtained in Preparation Example 1. Detailed Description of the Invention

[0038] The following takes specific examples to further explain and illustrate the technical solution of the present invention.

[0039] The polypropylene is K8009, and the melt index is 8.5 g / 10min under the conditions of 230 °C and 2.16 kg.

[0040] Preparation Example 1

[0041] .

[0042] Add 10 ml of dichloromethane, 0.5 mol of carbon tetrachloride, 5 mmol of maleic hydrazide, and 11 mmol of DOPO to the reaction vessel. Dropwise add 0.5 mol of triethylamine at room temperature and react at 70 °C for 6 h. After the reaction is completed, rotary evaporate to remove dichloromethane and carbon tetrachloride. The remaining solid is slurried with ethanol and purified twice to remove triethylamine hydrochloride and other impurities. Separate by column chromatography and recrystallize to obtain a white powdery sample with a yield of 86.3% and an HPLC purity of 99.4%.

[0043] Figure 1 is the 1 1H NMR spectrum of the product obtained in Preparation Example 1. Figure 2 is the 31 31P NMR spectrum of the product prepared in Preparation Example 1. Doublets appear at 6.52 ppm and 6.72 ppm, and the chemical shifts are similar, indicating that the compound is a pair of diastereoisomers. Figure 3 is the mass spectrum of the product prepared in Preparation Example 1. The molecular ion peak with a mass-to-charge ratio (m / z) of 541.1 is used to finally determine the relative molecular weight of the compound, and two DOPOs are coupled to maleic hydrazide. Figure 4 is the DSC spectrum of the product obtained in Preparation Example 1. Figure 5 is the TGA spectrum of the product obtained in Preparation Example 1. The compound has two melting points, further indicating that the compound is a pair of diastereoisomers. The compound structure contains carbon-carbon double bonds, so it is prone to break and decompose at the carbon-carbon double bonds during thermogravimetric analysis.

[0044] Preparation Example 2

[0045] Add 10 ml of dichloromethane, 1 ml of methanol, 0.5 mol of carbon tetrachloride, 5 mmol of maleic hydrazide, 11 mmol of DOPO, and 0.5 mmol of lithium chloride to the reaction vessel. Dropwise add 0.5 mol of triethylamine at room temperature and react at 70 °C for 6 h. After the reaction is completed, rotary evaporate to remove dichloromethane, methanol, and carbon tetrachloride. The remaining solid is slurried with ethanol and purified twice to remove triethylamine hydrochloride and other impurities. Separate by column chromatography and recrystallize to obtain a white powdery sample with a yield of 94.2% and an HPLC purity of 99.6%.

[0046] That is, compared with Preparation Example 1, Preparation Example 2 further added 0.5 mmol of lithium chloride and 1 ml of methanol.

[0047] Preparation Example 3

[0048] 10 ml of dichloromethane, 0.5 mol of carbon tetrachloride, 5 mmol of maleic hydrazide, 11 mmol of DOPO, and 0.5 mmol of lithium chloride were added to the reaction vessel. Triethylamine (0.5 mol) was added dropwise at room temperature, and the reaction was carried out at 70 °C for 6 h. After the reaction, dichloromethane, methanol, and carbon tetrachloride were removed by rotary evaporation. The remaining solid was slurried with ethanol and purified twice to remove triethylamine hydrochloride and other impurities. Then, it was separated by column chromatography and recrystallized to obtain a white powdery sample with a yield of 90.7% and an HPLC purity of 99.4%.

[0049] That is, compared with Preparation Example 1, Preparation Example 3 further added 0.5 mmol of lithium chloride.

[0050] Preparation Example 4

[0051] 10 ml of dichloromethane, 1 ml of methanol, 0.5 mol of carbon tetrachloride, 5 mmol of maleic hydrazide, and 11 mmol of DOPO were added to the reaction vessel. Triethylamine (0.5 mol) was added dropwise at room temperature, and the reaction was carried out at 70 °C for 6 h. After the reaction, dichloromethane, methanol, and carbon tetrachloride were removed by rotary evaporation. The remaining solid was slurried with ethanol and purified twice to remove triethylamine hydrochloride and other impurities. Then, it was separated by column chromatography and recrystallized to obtain a white powdery sample with a yield of 86.8% and an HPLC purity of 99.4%.

[0052] That is, compared with Preparation Example 1, Preparation Example 4 further added 1 ml of methanol.

[0053] Through the comparison of Examples 1-4, it can be seen that adding metal chlorides and methanol can significantly improve the product yield. Adding only metal chlorides can also increase the yield, but not significantly; only increasing C1-3 alcohols results in a small increase in yield.

[0054] Example 1

[0055] 100 parts by mass of polypropylene K8009, 8 parts by mass of the reactive flame retardant prepared in Preparation Example 1, 5 parts by mass of vinyltriethoxysilane, and 0.3 parts by mass of dicumyl peroxide were mixed evenly by a high-speed mixer and then added to a twin-screw extruder. Melting extrusion granulation was carried out at 190-230 °C and a screw speed of 300 rpm to obtain graft-modified anti-aging flame-retardant polypropylene.

[0056] Example 2

[0057] Other conditions were the same as those in Example 1, except that the amount of the reactive flame retardant described in formula (I) was 10 parts by mass.

[0058] Example 3

[0059] Other conditions are the same as those in Example 1, except that the amount of the reactive flame retardant described in formula (I) is 12 parts by mass.

[0060] Comparative Example 1

[0061] Other conditions are the same as those in Example 1, except that the reactive flame retardant described in formula (I) is not added.

[0062] Comparative Example 2

[0063] Other conditions are the same as those in Example 1, except that vinyltriethoxysilane is not added.

[0064] Comparative Example 3

[0065] 100 parts by mass of polypropylene K8009 and 26 parts by mass of tris(2-hydroxyethyl)aminomethyl phosphate are uniformly mixed by a high-speed mixer and added to a twin-screw extruder. Melting extrusion granulation is carried out at 190 - 230 °C and a screw speed of 300 rpm to obtain flame-retardant polypropylene.

[0066] Application Example

[0067] The flame retardant properties of the polypropylene obtained in the above examples and comparative examples were tested, and the results are shown in Table 1 below:

[0068] The double 85 laboratory samples were placed at 85 °C and 85 RH% for 30 days, and the limiting oxygen index (LOI) was measured after drying.

[0069] Table 1 Flame Retardant and Mechanical Property Tests of Polypropylene

[0070] 。

[0071] It can be seen from the data in Table 1 that in the present invention, by adding a self-made nitrogen-phosphorus synergistic reactive flame retardant and a vinylsilane coupling agent to polypropylene and completing the modification of polypropylene through melt grafting, the flame retardancy of polypropylene is significantly improved, and the flame retardancy has excellent weather resistance. After long-term high-temperature and high-humidity aging under double 85 conditions, the flame retardant performance basically does not decrease. In addition to improving the weather resistance of the flame retardant performance, the nitrogen-phosphorus synergistic reactive flame retardant of the present invention also has the advantages of less addition amount and little influence on the mechanical properties of polyolefins.

Claims

1. A graft-modified anti-aging and flame-retardant polypropylene, characterized in that, It comprises the following raw materials in parts by mass: 100 parts of polyolefin, 4 - 7 parts of vinylsilane coupling agent, 8 - 15 parts of the reactive flame retardant shown in formula (I): (I)。 2. The graft-modified anti-aging and flame-retardant polypropylene according to claim 1, wherein, It comprises the following raw materials in parts by mass: 100 parts of polyolefin, 4 - 7 parts of vinylsilane coupling agent, 10 - 12 parts of the reactive flame retardant shown in formula (I).

3. The graft-modified anti-aging flame-retardant polypropylene according to claim 1, wherein The polyolefin is selected from at least one of polyethylene and polypropylene; the melt index of the polyolefin is 5 - 100 g / 10 min under the conditions of 230 °C and 2.16 kg; and / or the vinylsilane coupling agent is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, and γ-methacryloxypropyltrimethoxysilane.

4. The graft-modified anti-aging flame-retardant polypropylene according to claim 1, wherein The reactive flame retardant shown in formula (I) is prepared by a preparation method comprising the following steps: maleic hydrazide and DOPO react in the presence of an acid-binding agent and a halogenating reagent, and then post-treatment is carried out; the synthesis route is as follows: 。 5. The graft-modified anti-aging flame-retardant polypropylene according to claim 4, wherein The acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and tetramethylguanidine; the halogenating reagent is carbon tetrachloride.

6. The graft-modified anti-aging and flame-retardant polypropylene according to claim 4, wherein The molar ratio of maleic hydrazide, DOPO, the acid-binding agent, and the halogenating reagent is 1:2.1 - 2.5:50 - 100:50 - 100.

7. The graft-modified anti-aging and flame-retardant polypropylene according to claim 4, characterized in that, The reaction solvent is a halogenated hydrocarbon, and the halogenated hydrocarbon is selected from at least one of dichloromethane and dichloroethane. The reaction conditions are to react at 50 - 80 °C for 5 - 15 h.

8. The graft-modified anti-aging and flame-retardant polypropylene according to claim 4, wherein When adding the acid-binding agent, a halogenated salt with a molar amount 0.05 - 0.1 times that of maleic hydrazide is also added, and the reaction solvent is a mixed solvent of a halogenated hydrocarbon and an alcohol with C1 - 3 in a volume ratio of 10:1 - 2; the halogenated salt is selected from lithium chloride, zinc chloride, ferric chloride, and aluminum chloride.

9. The preparation method of the graft-modified anti-aging and flame-retardant polypropylene according to claim 1 or any one of claims 3 to 7, characterized in that, It comprises the following steps: (S1) Maleic hydrazide and DOPO react in the presence of an acid-binding agent and a halogenating reagent to prepare the reactive flame retardant shown in formula (I); (S2) 100 parts by mass of polyolefin, 8 - 15 parts by mass of the reactive flame retardant shown in formula (I), 4 - 7 parts by mass of vinylsilane coupling agent, and 0.1 - 0.5 parts by mass of an initiator are mixed evenly, added to a twin-screw extruder, and melt-extruded and pelletized to obtain graft-modified anti-aging flame-retardant polypropylene.

10. The preparation method according to claim 9, wherein, The initiator is selected from at least one of dicumyl peroxide, di-tert-butyl peroxide cumene, dicyclohexyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, and tert-butyl perpivalate; In step (S2), the mixing method is a high-speed mixer; the process conditions for melt-extrusion and pelletization are 190 - 230 °C and a screw speed of 200 - 300 rpm.

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