Anti-aging polypropylene material and preparation method thereof

Abstract

The invention discloses an anti-aging polypropylene material and a preparation method thereof, and relates to the technical field of materials. The anti-aging polypropylene material prepared by the invention comprises modified polypropylene and modified silicon dioxide, and the modified polypropylene is obtained by grafting polypropylene with a polyhedral oligomeric silsesquioxane monomer, then reacting with cyclopentadiene lithium, and then reacting with dichloroketene; the modified silicon dioxide is prepared by the following steps: grafting pretreated silicon dioxide with polydichlorophosphazene, reacting with 2-tert-butoxycarbonylamino-5-methyl hydroxybenzoate, carrying out alkaline hydrolysis, and carrying out diazonium salt coupling, acylating chlorination and 4-(chloroethoxy) aniline nucleophilic condensation cyclization reaction to generate the modified silicon dioxide. The anti-aging polypropylene material prepared by the preparation method disclosed by the invention has good flame-retardant and anti-aging properties.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly to an anti-aging polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene material is a thermoplastic polymer material prepared by the polymerization reaction of propylene monomers. It is widely used in many fields due to its light weight, high strength, good chemical corrosion resistance, electrical insulation and excellent processing and forming properties. The large number of carbon-hydrogen bonds and non-polar characteristics in its molecular structure make it show stable physical and chemical properties in most environments.

[0003] However, in practical applications, it faces many challenges, especially the problem of material aging when exposed to outdoor environments or high-temperature conditions for a long time. Since there are tertiary carbon atoms in the polypropylene molecular chain, this structure is extremely prone to initiate free radical chain reactions under ultraviolet irradiation or high-temperature environments. The energy of ultraviolet rays can directly break the chemical bonds in the molecular chain, generate free radicals, and further promote oxidative degradation, resulting in a significant reduction in the mechanical properties of the material. In high-temperature environments, thermo-oxidative aging will accelerate the oxidative reaction process, produce peroxides and free radicals, and exacerbate the molecular chain breakage. This dual aging mechanism severely limits the service life and reliability of polypropylene in scenarios such as outdoor buildings, automotive parts or industrial equipment that need to withstand sunlight irradiation and high temperatures for a long time. Therefore, the development of modification technologies for anti-ultraviolet and thermo-oxidative aging has become the key to improving the durability of materials.

[0004] In addition, the flammability of polypropylene is also an important defect in its applications. The large number of carbon-hydrogen bonds in its molecular structure cause it to release a large amount of heat and toxic smoke when burning, belonging to a flammable material, which poses a safety hazard in scenarios with strict fire protection requirements such as electronic and electrical equipment, automotive interiors or building facades. Therefore, constructing an anti-aging system and endowing flame retardant properties has become the key technical path to improving the comprehensive performance of polypropylene. These modification methods can not only significantly extend the service life of materials in outdoor, high-temperature or humid environments, but also meet the increasingly strict industry safety standards and functional requirements, thus promoting the application expansion of polypropylene in more high-value-added fields. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-aging polypropylene material and a preparation method thereof to solve the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A preparation method of an anti-aging polypropylene material, comprising the following preparation steps:

[0008] (1) Mix polypropylene, cage-like silsesquioxane monomer, dicumyl peroxide, and additives evenly, and add them to a single-screw extruder for melt blending to obtain organosilicon-modified polypropylene, with a melting temperature of 190 - 210 °C;

[0009] (2) Mix organosilicon-modified polypropylene, tetrahydrofuran, and ferric chloride in a mass ratio of 1:(20 - 30):(0.05 - 0.1) for 1 h, cool down to -20 °C, add lithium cyclopentadienyl which is 1.4 - 1.5 times the mass of the organosilicon-modified polypropylene, heat up to 0 °C and continue stirring for 12 - 14 h, add a saturated ammonium chloride solution which is 20 - 30 times the mass of the organosilicon-modified polypropylene and stir for 5 - 10 min, and obtain pre-modified polypropylene after filtration, washing, and drying;

[0010] (3) React the pre-modified polypropylene with dichloroketene to obtain modified polypropylene;

[0011] (4) Mix pretreated silica and polydichlorophosphazene to obtain phosphorus-containing silica; mix the phosphorus-containing silica and sodium salt to obtain pre-modified silica; mix the pre-modified silica, sodium hydroxide, and pure water to obtain amino-carboxyl silica;

[0012] (5) Diazotize the amino-carboxyl silica to obtain diazo silica; diazotize anthranilic acid to obtain a diazo solution; mix selenium powder, potassium borohydride, and sodium hydroxide to obtain a selenium solution; mix the diazo silica, selenium solution, and diazo solution to obtain selenium-modified silica; acyl chloride the selenium-modified silica to obtain acyl chloride silica; react the acyl chloride silica with 4-(chloroethoxy)aniline to obtain modified silica;

[0013] (6) Mix the modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide in a mass ratio of 1:(0.1 - 0.15):(5 - 6):(30 - 40):0.01, reflux and react at 100 - 110 °C for 20 - 30 min, and then dry in an oven at 180 °C to obtain the anti-aging polypropylene material.

[0014] As an optimization, the preparation method of the cage - type silsesquioxane monomer in step (1) is as follows: Mix bromobutyltrimethoxysilane and acetone, heat up to 50 - 60 °C and stir for 30 - 40 min, then dropwise add pure water at a dropping rate of 0.4 mL / min, heat up to 70 - 80 °C and reflux for 24 h, cool to room temperature and then perform suction filtration, wash successively with acetone, pyridine, 1 mol / L hydrochloric acid, pure water, and dry to obtain the precursor; the mass ratio of bromobutyltrimethoxysilane, acetone, and pure water is 1:(5 - 7.5):(4.5 - 5); Mix the precursor, tetrahydrofuran, and N,N - diethylamine in a mass ratio of 1:(30 - 40):(15 - 20), heat up to 65 - 70 °C and stir for 5 - 10 min, add a 7 - octenyltrimethoxysilane solution, which is prepared by using tetrahydrofuran and 7 - octenyltrimethoxysilane with a mass 1 - 1.5 times that of the precursor, and the concentration is 0.2 g / mL, continue to reflux for 24 h, after the reaction is completed, cool to room temperature, perform suction filtration, wash with 1 mol / L hydrochloric acid and pure water, and dry to obtain the cage - type silsesquioxane monomer.

[0015] As an optimization, the mass ratio of the polypropylene, cage - type silsesquioxane monomer, diisopropylbenzene peroxide, and the additive is 1:(0.1 - 0.2):(0.001 - 0.002):(0.001 - 0.002); the polypropylene model is T30S, purchased from Yangzi Petrochemical Co., Ltd., Sinopec; the additive is antioxidant 1010.

[0016] As an optimization, the preparation method of the modified polypropylene in step (3) is as follows: Mix the pre - modified polypropylene and tetrahydrofuran, dropwise add dichloroethenone at a rate of 0.1 mL / min at 0 - 5 °C, add triethylamine, heat up to room temperature and stir for 5 - 6 h, filter and then add it to an acetic acid potassium - glacial acetic acid solution, add 98 wt% concentrated hydrochloric acid, heat up to 80 - 90 °C and reflux for 24 h, filter, wash, and dry to obtain the modified polypropylene; the mass ratio of the pre - modified polypropylene, tetrahydrofuran, dichloroethenone, triethylamine, acetic acid potassium - glacial acetic acid solution, and 98 wt% concentrated hydrochloric acid is 1:(20 - 30):(1.4 - 1.5):(2.0 - 2.5):(40 - 50):(2 - 3); the acetic acid potassium - glacial acetic acid solution is obtained by mixing acetic acid potassium, glacial acetic acid, and pure water in a mass ratio of 1:5:15.

[0017] As an optimization, the preparation method of the amino-carboxyl silica in step (4) is as follows: Mix silica, absolute ethanol, 3-aminopropyltrimethoxysilane, and pure water in a mass ratio of 1:(20 - 25):(4.5 - 5.5):(10 - 12), heat up to 70 - 80 °C and react for 5 - 6 h, then obtain pretreated silica through filtration, washing, and drying; Mix methyl 2-amino-5-hydroxybenzoate, di-tert-butyl dicarbonate, and ethanol in a mass ratio of 1:(1.3 - 1.5):(50 - 60), react at 35 - 40 °C for 24 h, and obtain methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate through ethanol concentration and recrystallization; Mix methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate, sodium hydride, and tetrahydrofuran in a mass ratio of 1:(0.25 - 0.30):(10 - 12) for 4 - 5 h, filter and retain the supernatant to obtain the sodium salt; Mix the pretreated silica, polydichlorophosphazene, triethylamine, and tetrahydrofuran in a mass ratio of 1:(0.2 - 0.3):(2 - 3):(20 - 30), heat up to 60 - 70 °C and react for 10 - 12 h, then obtain phosphorus-containing silica through filtration, washing, and drying; Under nitrogen protection, mix the phosphorus-containing silica, the sodium salt, and dimethyl sulfoxide in a mass ratio of 1:(15 - 20):(20 - 30), heat up to 115 - 120 °C and react for 72 h, then obtain pre-modified silica through filtration, washing, and drying; Mix the pre-modified silica, sodium hydroxide, and pure water in a mass ratio of 1:(0.3 - 0.5):(10 - 12), stir at 50 - 60 °C for 4 - 5 h, then obtain amino-carboxyl silica through filtration, washing, and drying.

[0018] As an optimization, the preparation method of the modified silica in step (5) is as follows: Mix diazo silica and selenium solution at 0 - 4 °C for 30 - 40 min, add the diazo solution, heat up to 60 - 70 °C and stir for 3 - 4 h, cool down to room temperature and stir for 2 - 3 h, adjust the pH to 1 - 2 with 60 wt% hydrochloric acid, then obtain selenium-modified silica through filtration, washing, and drying; Mix the selenium-modified silica and thionyl chloride in a mass ratio of 1:(3 - 4), heat up to 75 - 80 °C and reflux for 3 - 4 h, then obtain acyl chloride-modified silica through filtration and drying; The mass ratio of diazo silica, diazo solution, and selenium solution is 1:(5 - 6):(200 - 250); Mix 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether, cool down to 0 - 5 °C, add the acyl chloride-modified silica, heat up to room temperature and react for 4 - 5 h, then obtain modified silica through filtration, washing, and drying; The mass ratio of acyl chloride-modified silica, 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether is 1:(5 - 6):(2 - 2.5):(5 - 6):(20 - 30).

[0019] As an optimization, the preparation method of the diazo silica is as follows: Mix amino-carboxyl silica, pure water, and 98 wt% concentrated hydrochloric acid in a mass ratio of 1:(5 - 6):(5 - 6), cool to 0 - 4 °C, add a 0.5 g / mL sodium nitrite solution that is 0.8 - 1.0 times the volume of pure water, stir for 1 - 2 h, and filter to obtain diazo silica; the preparation method of the diazo solution is as follows: Mix anthranilic acid, pure water, and 98 wt% concentrated hydrochloric acid in a mass ratio of 1:(1.4 - 1.6):(1.4 - 1.6), cool to 0 - 4 °C, add a 0.5 g / mL sodium nitrite solution that is 0.8 - 1.0 times the volume of pure water, stir for 1 - 2 h to obtain the diazo solution; the preparation method of the selenium solution is as follows: Under nitrogen protection, mix 1 / 3 of the total amount of selenium powder, pure water, and a 0.18 g / mL potassium borohydride solution for 20 - 30 min, add the remaining selenium powder, continue to stir for 30 - 40 min, and add a 0.4 g / mL sodium hydroxide solution to obtain the selenium solution; the mass ratio of selenium powder, pure water, 0.18 g / mL potassium borohydride solution, and 0.4 g / mL sodium hydroxide solution is 1:(20 - 30):(20 - 30):(20 - 30).

[0020] The present invention also provides an anti-aging polypropylene material prepared by the preparation method of the above anti-aging polypropylene material.

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

[0022] When preparing the anti-aging polypropylene material of the present invention, first, graft polyhedral oligomeric silsesquioxane monomers onto polypropylene, then react with lithium cyclopentadienide, and then react with dichloroethenone to obtain modified polypropylene; second, after grafting polydichlorophosphazene onto pretreated silica, react with methyl 2-tert-butoxycarbonylamino-5-hydroxybenzoate, after alkaline hydrolysis, then generate modified silica through diazonium salt coupling, acyl chlorination, and nucleophilic condensation cyclization reaction of 4-(chloroethoxy)aniline, and finally, mix the modified polypropylene and the modified silica to obtain the anti-aging polypropylene material;

[0023] First, a cage - type sesquioxane monomer containing heptabromobutyl and monovinyl groups will be prepared by the vertex - capping method, and melt - grafted with polypropylene through the double bond on the monomer. Cage - type sesquioxane is an organic - inorganic hybrid material with a nanoscale cage - like structure. Its unique three - dimensional configuration and high surface activity can form a good interfacial bond with the polypropylene matrix, thus effectively improving the thermal stability of the material and endowing the material with hydrophobic properties. Lithium cyclopentadienide and bromobutane undergo a nucleophilic substitution reaction to graft cyclopentadiene onto the side chain of polypropylene. Starting from cyclopentadiene, a tropolone structure is generated through a cycloaddition reaction with dichloroethenone. Tropolone contains a conjugated system of a carbonyl group and an enone group. This conjugated structure can absorb ultraviolet light through n→π* and π→π* electronic transitions, and convert the excited - state energy into heat energy through intramolecular energy transfer, thereby protecting the polymer molecular chain from photo - degradation and achieving the performance of anti - ultraviolet aging.

[0024] Secondly, the amino group on methyl 2 - amino - 5 - hydroxybenzoate is protected to form 2 - tert - butoxycarbonylamino - 5 - hydroxybenzoate. Pretreated silica with amino groups on its surface is grafted with polydichlorophosphazene. When polydichlorophosphazene decomposes upon heating, it generates non - combustible gases that can dilute the concentration of combustibles and isolate oxygen. At the same time, the generated phosphorus - containing free radicals can capture the active free radicals in the combustion chain reaction, effectively inhibiting flame propagation. Combining the synergistic effect of phosphorus and nitrogen elements endows the material with high - efficiency flame - retardant properties. After activating 2 - tert - butoxycarbonylamino - 5 - hydroxybenzoate into its sodium salt and reacting it with polydichlorophosphazene, in the presence of sodium hydroxide, the ester group is hydrolyzed into a carboxyl group, and the amino - protecting group tert - butoxycarbonyl is removed to regenerate the amino group, obtaining a structure with adjacent amino and carboxyl groups on the benzene ring. Then, through diazonium salt coupling, acyl chlorination, and nucleophilic condensation cyclization reaction with 4 - (chloroethoxy)aniline, a benzisoselenazole - one structure is generated. Selenium atoms have a unique electronic structure and can capture free radicals through single - electron transfer or hydrogen - atom transfer to terminate the oxidation chain reaction. The 4 - (chloroethoxy)aniline provides the conjugated system of the benzene ring to stabilize the reaction intermediate, and at the same time reduces steric hindrance, making the active site more accessible to free radicals, thereby improving the antioxidant performance. As an inorganic filler, silica's high hardness and rigidity can significantly enhance the wear resistance and dimensional stability of polypropylene.

[0025] Finally, polypropylene and modified silica are mixed into a film to obtain an anti - aging polypropylene material. The hydroxyl group on the tropolone of the polypropylene side chain and the chlorine on the chloroethoxy group of silica undergo an etherification reaction to form a cross - linked network between polypropylene and silica, thereby enhancing the mechanical properties of the material. Specific embodiments

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] In the following examples and comparative examples, the polypropylene model is T30S, purchased from Yangzi Petrochemical Co., Ltd., Sinopec; the additive is antioxidant 1010; the particle size of the silica is 200 nm.

[0028] Example 1:

[0029] A preparation method of an anti-aging polypropylene material, the preparation method of the anti-aging polypropylene material includes the following preparation steps:

[0030] (1) Mix bromobutyltrimethoxysilane and acetone, heat up to 60 °C and stir for 40 min, then dropwise add pure water at a dropping rate of 0.4 mL / min, heat up to 80 °C and reflux for 24 h, cool to room temperature and then filter by suction, wash successively with acetone, pyridine, 1 mol / L hydrochloric acid, pure water, and dry to obtain a precursor; the mass ratio of bromobutyltrimethoxysilane, acetone, and pure water is 1:5:4.5; use tetrahydrofuran to prepare a 7-octenyltrimethoxysilane solution with a concentration of 0.2 g / mL from 7-octenyltrimethoxysilane with a mass 1 time that of the precursor; mix the precursor, tetrahydrofuran, and N,N-diethylethylamine in a mass ratio of 1:30:15, heat up to 70 °C and stir for 10 min, add the 7-octenyltrimethoxysilane solution, and continue reflux for 24 h. After the reaction is completed, cool to room temperature, filter by suction, wash with 1 mol / L hydrochloric acid and pure water, and dry to obtain a cage-like silsesquioxane monomer; mix polypropylene, cage-like silsesquioxane monomer, dicumyl peroxide, and additive in a mass ratio of 1:0.1:0.001:0.001, add to a single-screw extruder for melt blending to obtain organosilicon-modified polypropylene, and the melting temperature is 210 °C;

[0031] (2) Mix the organosilicon-modified polypropylene, tetrahydrofuran, and ferric chloride in a mass ratio of 1:20:0.05 for 1 h, cool to -20 °C, add cyclopentadienyl lithium with a mass 1.4 times that of the organosilicon-modified polypropylene, heat up to 0 °C and continue stirring for 14 h, add a saturated ammonium chloride solution with a mass 20 times that of the organosilicon-modified polypropylene and stir for 10 min, and obtain pre-modified polypropylene after filtration, washing, and drying;

[0032] (3) Mix pre-modified polypropylene and tetrahydrofuran, and drop dichloroethenone at a rate of 0.1 mL / min at 5 °C. Add triethylamine, heat up to room temperature and stir for reaction for 6 h. After filtration, add it to the potassium acetate - glacial acetic acid solution, add 98 wt% concentrated hydrochloric acid, heat up to 90 °C and reflux for reaction for 24 h. After filtration, washing and drying, modified polypropylene is obtained; the mass ratio of pre-modified polypropylene, tetrahydrofuran, dichloroethenone, triethylamine, potassium acetate - glacial acetic acid solution, and 98 wt% concentrated hydrochloric acid is 1:20:1.4:2.0:40:2; the potassium acetate - glacial acetic acid solution is obtained by mixing potassium acetate, glacial acetic acid, and pure water according to the mass ratio of 1:5:15;

[0033] (4) Mix pretreated silica, polydichlorophosphazene, triethylamine, and tetrahydrofuran according to the mass ratio of 1:0.2:2:20, heat up to 70 °C and react for 12 h. After filtration, washing and drying, phosphorus-containing silica is obtained; mix methyl 2-amino-5-hydroxybenzoate, di-tert-butyl dicarbonate, and ethanol according to the mass ratio of 1:1.3:0 (it seems there is a mistake here, assuming it should be a certain value), react at 40 °C for 24 h, concentrate ethanol and recrystallize to obtain methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate; mix methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate, sodium hydride, and tetrahydrofuran according to the mass ratio of 1:0.25:10 for 5 h, filter and retain the supernatant to obtain the sodium salt; under nitrogen protection, mix phosphorus-containing silica, sodium salt, and dimethyl sulfoxide according to the mass ratio of 1:15:20, heat up to 120 °C and react for 72 h. After filtration, washing and drying, pre-modified silica is obtained; mix pre-modified silica, sodium hydroxide, and pure water according to the mass ratio of 1:0.3:10, stir at 60 °C for 5 h. After filtration, washing and drying, amino-carboxyl silica is obtained;

[0034] (5) Mix amino-carboxyl silica, pure water, and 98 wt% concentrated hydrochloric acid at a mass ratio of 1:5:5, cool to 4 °C, add a 0.5 g / mL sodium nitrite solution that is 0.8 times the volume of pure water, stir for 2 h, and filter to obtain diazo silica; mix o-aminobenzoic acid, pure water, and 98 wt% concentrated hydrochloric acid at a mass ratio of 1:1.4:1.4, cool to 4 °C, add a 0.5 g / mL sodium nitrite solution that is 0.8 times the volume of pure water, stir for 2 h to obtain a diazo solution; under nitrogen protection, mix 1 / 3 of the total amount of selenium powder, pure water, and a 0.18 g / mL potassium borohydride solution for 30 min, add the remaining selenium powder, continue to stir for 40 min, and add a 0.4 g / mL sodium hydroxide solution to obtain a selenium solution; the mass ratio of selenium powder, pure water, 0.18 g / mL potassium borohydride solution, and 0.4 g / mL sodium hydroxide solution is 1:20:20:20; mix diazo silica and the selenium solution at 4 °C for 40 min, add the diazo solution, heat up to 70 °C and stir for 4 h, cool to room temperature and stir for 3 h, adjust the pH to 2 with 60 wt% hydrochloric acid, filter, wash, and dry to obtain selenium-modified silica; mix selenium-modified silica and thionyl chloride at a mass ratio of 1:3, heat up to 75 - 80 °C and reflux for 3 - 4 h, filter and dry to obtain acyl chloride silica; the mass ratio of diazo silica, diazo solution, and selenium solution is 1:5:200; mix 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether, cool to 5 °C, add acyl chloride silica, heat up to room temperature and react for 4 - 5 h, filter, wash, and dry to obtain modified silica. The mass ratio of acyl chloride silica, 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether is 1:5:2:5:20.

[0035] (6) Mix modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide at a mass ratio of 1:0.1:5:30:0.01, reflux at 110 °C for 30 min, and then dry in an oven at 180 °C to obtain an anti-aging polypropylene material.

[0036] Example 2:

[0037] A preparation method of an anti-aging polypropylene material, the preparation method of the anti-aging polypropylene material includes the following preparation steps:

[0038] (1) Mix bromobutyltrimethoxysilane and acetone, heat up to 55 °C and stir for 35 min, then add pure water dropwise at a dropping rate of 0.4 mL / min, heat to 75 °C and reflux for 24 h. After cooling to room temperature, filter by suction, wash successively with acetone, pyridine, 1 mol / L hydrochloric acid, pure water, and dry to obtain the precursor; the mass ratio of bromobutyltrimethoxysilane, acetone, and pure water is 1:6:4.75; use tetrahydrofuran to prepare a 7-octenyltrimethoxysilane solution with a concentration of 0.2 g / mL from 7-octenyltrimethoxysilane with a mass 1.25 times that of the precursor; mix the precursor, tetrahydrofuran, and N,N-diethylethylamine at a mass ratio of 1:35:17.5, heat up to 67.5 °C and stir for 7.5 min, add the 7-octenyltrimethoxysilane solution, and continue reflux for 24 h. After the reaction is completed, cool to room temperature, filter by suction, wash with 1 mol / L hydrochloric acid and pure water, and dry to obtain the cage-shaped silsesquioxane monomer; mix polypropylene, the cage-shaped silsesquioxane monomer, dicumyl peroxide, and the auxiliary agent at a mass ratio of 1:0.15:0.0015:0.0015, add them to a single-screw extruder for melt blending to obtain organosilicon-modified polypropylene, and the melting temperature is 200 °C;

[0039] (2) Mix organosilicon-modified polypropylene, tetrahydrofuran, and ferric chloride at a mass ratio of 1:250.08 for 1 h, cool to -20 °C, add lithium cyclopentadienyl with a mass 1.45 times that of the organosilicon-modified polypropylene, heat to 0 °C and continue stirring for 13 h, add a saturated ammonium chloride solution with a mass 25 times that of the organosilicon-modified polypropylene and stir for 7.5 min, and obtain the pre-modified polypropylene after filtration, washing, and drying;

[0040] (3) Mix the pre-modified polypropylene and tetrahydrofuran, add dichloroethenone dropwise at a rate of 0.1 mL / min at 2.5 °C, add triethylamine, heat to room temperature and stir for 5.5 h, filter and add to the potassium acetate - glacial acetic acid solution, add 98 wt% concentrated hydrochloric acid, heat to 85 °C and reflux for 24 h, and obtain the modified polypropylene after filtration, washing, and drying; the mass ratio of the pre-modified polypropylene, tetrahydrofuran, dichloroethenone, triethylamine, potassium acetate - glacial acetic acid solution, and 98 wt% concentrated hydrochloric acid is 1:25:1.45:2.25:45:2.5; the potassium acetate - glacial acetic acid solution is obtained by mixing potassium acetate, glacial acetic acid, and pure water at a mass ratio of 1:5:15;

[0041] (4) Mix the pretreated silica, polydichlorophosphazene, triethylamine, and tetrahydrofuran in a mass ratio of 1:0.25:2.5:25, heat up to 65 °C and react for 11 h, and obtain phosphorus-containing silica through filtration, washing, and drying; mix methyl 2-amino-5-hydroxybenzoate, di-tert-butyl dicarbonate, and ethanol in a mass ratio of 1:1.4:55, react at 37.5 °C for 24 h, and obtain methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate through ethanol concentration and recrystallization; mix methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate, sodium hydride, and tetrahydrofuran in a mass ratio of 1:0.275:11 for 4.5 h, filter and retain the supernatant to obtain the sodium salt; under nitrogen protection, mix the phosphorus-containing silica, the sodium salt, and dimethyl sulfoxide in a mass ratio of 1:17.5:25, heat up to 117.5 °C and react for 72 h, and obtain pre-modified silica through filtration, washing, and drying; mix the pre-modified silica, sodium hydroxide, and pure water in a mass ratio of 1:0.4:11, stir at 55 °C for 4.5 h, and obtain amino-carboxyl silica through filtration, washing, and drying.

[0042] (5) Mix the amino-carboxyl silica, pure water, and 98 wt% concentrated hydrochloric acid in a mass ratio of 1:5.5:5.5, cool to 3 °C, add a 0.5 g / mL sodium nitrite solution that is 0.85 times the volume of pure water, stir for 1.8 h, and filter to obtain diazo silica; mix anthranilic acid, pure water, and 98 wt% concentrated hydrochloric acid in a mass ratio of 1:1.5:1.5, cool to 3 °C, add a 0.5 g / mL sodium nitrite solution that is 0.85 times the volume of pure water, and stir for 1.8 h to obtain a diazo solution; under nitrogen protection, mix 1 / 3 of the total amount of selenium powder, pure water, and a 0.18 g / mL potassium borohydride solution for 25 min, add the remaining selenium powder, continue to stir for 35 min, add a 0.4 g / mL sodium hydroxide solution to obtain a selenium solution; the mass ratio of selenium powder, pure water, 0.18 g / mL potassium borohydride solution, and 0.4 g / mL sodium hydroxide solution is 1:22:22:22; mix the diazo silica and the selenium solution at 3 °C for 35 min, add the diazo solution, heat up to 68 °C and stir for 3.5 h, cool to room temperature and stir for 2.5 h, adjust the pH to 1.8 with 60 wt% hydrochloric acid, and obtain selenium-modified silica through filtration, washing, and drying; mix the selenium-modified silica and thionyl chloride in a mass ratio of 1:3.3, heat up to 77 °C and reflux for 3.5 h, and obtain acyl chloride silica through filtration and drying; the mass ratio of diazo silica, diazo solution, and selenium solution is 1:5.5:220; mix 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether, cool to 4 °C, add the acyl chloride silica, heat up to room temperature and react for 4.5 h, and obtain modified silica through filtration, washing, and drying; the mass ratio of acyl chloride silica, 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether is 1:5.5:2.2:5.5:22.

[0043] (6) Mix modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide in a mass ratio of 1:0.125:5.5:35:0.01. After refluxing at 105 °C for 25 min, dry it in an oven at 180 °C to obtain the anti-aging polypropylene material.

[0044] Example 3:

[0045] A preparation method of an anti-aging polypropylene material, the preparation method of the anti-aging polypropylene material comprising the following preparation steps:

[0046] (1) Mix bromobutyltrimethoxysilane and acetone, heat up to 50 °C and stir for 30 min, then dropwise add pure water at a dropping rate of 0.4 mL / min, heat to 70 °C and reflux for 24 h. After cooling to room temperature, filter by suction, wash successively with acetone, pyridine, 1 mol / L hydrochloric acid, and pure water, and dry to obtain the precursor; the mass ratio of bromobutyltrimethoxysilane, acetone, and pure water is 1:7.5:5; use tetrahydrofuran to prepare a 7-octenyltrimethoxysilane solution with a concentration of 0.2 g / mL from 7-octenyltrimethoxysilane with a mass 1.5 times that of the precursor; mix the precursor, tetrahydrofuran, and N,N-diethylethylamine in a mass ratio of 1:40:20, heat up to 65 °C and stir for 5 min, add the 7-octenyltrimethoxysilane solution, and continue refluxing for 24 h. After the reaction is completed, cool to room temperature, filter by suction, wash with 1 mol / L hydrochloric acid and pure water, and dry to obtain the cage-like silsesquioxane monomer; mix polypropylene, cage-like silsesquioxane monomer, diisopropylbenzene peroxide, and auxiliary agent in a mass ratio of 1:0.2:0.002:0.002, add them to a single-screw extruder for melt blending to obtain organosilicon-modified polypropylene, and the melting temperature is 190 °C;

[0047] (2) Mix organosilicon-modified polypropylene, tetrahydrofuran, and ferric chloride in a mass ratio of 1:30:0.1 for 1 h, cool down to -20 °C, add lithium cyclopentadienide with a mass 1.5 times that of the organosilicon-modified polypropylene, heat up to 0 °C and continue stirring for 12 h, add a saturated ammonium chloride solution with a mass 30 times that of the organosilicon-modified polypropylene and stir for 5 min, and obtain pre-modified polypropylene after filtration, washing, and drying;

[0048] (3) Mix pre-modified polypropylene and tetrahydrofuran, and drop dichloroethenone at a rate of 0.1 mL / min at 0 °C. Add triethylamine, heat up to room temperature and stir for reaction for 5 h. After filtration, add it to the potassium acetate - glacial acetic acid solution, add 98 wt% concentrated hydrochloric acid, heat up to 80 °C and reflux for reaction for 24 h. After filtration, washing and drying, modified polypropylene is obtained; the mass ratio of pre-modified polypropylene, tetrahydrofuran, dichloroethenone, triethylamine, potassium acetate - glacial acetic acid solution, and 98 wt% concentrated hydrochloric acid is 1:30:1.5:2.5:50:3; the potassium acetate - glacial acetic acid solution is obtained by mixing potassium acetate, glacial acetic acid, and pure water in a mass ratio of 1:5:15;

[0049] (4) Mix pretreated silica, polydichlorophosphazene, triethylamine, and tetrahydrofuran in a mass ratio of 1:0.3:3:30, heat up to 60 °C and react for 10 h. After filtration, washing and drying, phosphorus-containing silica is obtained; mix methyl 2-amino-5-hydroxybenzoate, di-tert-butyl dicarbonate, and ethanol in a mass ratio of 1:1.5:60, react at 35 °C for 24 h, and after concentrating ethanol and recrystallizing, methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate is obtained; mix methyl 2-(tert-butoxycarbonylamino)-5-hydroxybenzoate, sodium hydride, and tetrahydrofuran in a mass ratio of 1:0.30:12 for 4 h, and after filtration, retain the supernatant to obtain the sodium salt; under nitrogen protection, mix phosphorus-containing silica, the sodium salt, and dimethyl sulfoxide in a mass ratio of 1:20:30, heat up to 115 °C and react for 72 h. After filtration, washing and drying, pre-modified silica is obtained; mix pre-modified silica, sodium hydroxide, and pure water in a mass ratio of 1:0.5:12, stir at 50 °C for 4 h. After filtration, washing and drying, amino-carboxyl silica is obtained;

[0050] (5) Mix amino-carboxyl silica, pure water, and 98 wt% concentrated hydrochloric acid at a mass ratio of 1:6:6, cool to 0 °C, add a 0.5 g / mL sodium nitrite solution with a volume 1.0 times that of the pure water, stir for 1 h, and filter to obtain diazo silica; mix o-aminobenzoic acid, pure water, and 98 wt% concentrated hydrochloric acid at a mass ratio of 1:1.6:1.6, cool to 0 °C, add a 0.5 g / mL sodium nitrite solution with a volume 1.0 times that of the pure water, stir for 1 h to obtain a diazo solution; under nitrogen protection, mix 1 / 3 of the total amount of selenium powder, pure water, and a 0.18 g / mL potassium borohydride solution for 20 min, add the remaining selenium powder, continue to stir for 30 min, and add a 0.4 g / mL sodium hydroxide solution to obtain a selenium solution; the mass ratio of selenium powder, pure water, 0.18 g / mL potassium borohydride solution, and 0.4 g / mL sodium hydroxide solution is 1:30:30:30; mix diazo silica and the selenium solution at 0 °C for 30 min, add the diazo solution, heat up to 60 °C and stir for 3 h, cool to room temperature and stir for 2 h, adjust the pH to 1 with 60 wt% hydrochloric acid, filter, wash, and dry to obtain selenium-modified silica; mix the selenium-modified silica and thionyl chloride at a mass ratio of 1:4, heat up to 75 °C and reflux for 3 h, filter and dry to obtain acyl chloride silica; the mass ratio of diazo silica, diazo solution, and selenium solution is 1:6:250; mix 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether, cool to 0 °C, add acyl chloride silica, heat up to room temperature and react for 4 h, filter, wash, and dry to obtain modified silica. The mass ratio of acyl chloride silica, 4-(chloroethoxy)aniline, sodium bicarbonate, pure water, and ether is 1:6:2.5:6:30;

[0051] (6) Mix modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide at a mass ratio of 1:0.15:6:40:0.01, reflux at 100 °C for 20 min, and then dry in an oven at 180 °C to obtain an anti-aging polypropylene material.

[0052] Comparative Example 1:

[0053] The preparation method of the anti-aging polypropylene material in Comparative Example 1 is different from that in Example 2 in that the organosilicon-modified polypropylene is not modified. Specifically, steps (2) to (3) are not included, and step (6) is modified as follows: Mix organosilicon-modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide at a mass ratio of 1:0.15:6:40:0.01, reflux at 100 °C for 20 min, and then dry in an oven at 180 °C to obtain an anti-aging polypropylene material. The remaining steps are the same as in Example 2.

[0054] Comparative Example 2:

[0055] The preparation method of the anti-aging polypropylene material in Comparative Example 2 is different from that in Example 2 in that the silica is not modified, specifically, steps (4) to (5) are not included, and step (6) is modified as follows: the modified polypropylene, silica, pyridine, toluene, and tetrabutylammonium iodide are mixed at a mass ratio of 1:0.15:6:40:0.01, refluxed at 100 °C for 20 min, and then dried in an oven at 180 °C to obtain the anti-aging polypropylene material. The remaining steps are the same as those in Example 2.

[0056] Comparative Example 3:

[0057] The preparation method of the anti-aging polypropylene material in Comparative Example 3 is different from that in Example 2 in that the phosphorus-containing silica is not modified, specifically, step (5) is not included, and step (4) is modified as follows: the pretreated silica, polydichlorophosphazene, triethylamine, and tetrahydrofuran are mixed at a mass ratio of 1:0.25:2.5:25, heated to 65 °C and reacted for 11 h, and the phosphorus-containing silica is obtained through filtration, washing, and drying;

[0058] Step (6) is modified as follows: the modified polypropylene, phosphorus-containing silica, pyridine, toluene, and tetrabutylammonium iodide are mixed at a mass ratio of 1:0.15:6:40:0.01, refluxed at 100 °C for 20 min, and then dried in an oven at 180 °C to obtain the anti-aging polypropylene material. The remaining steps are the same as those in Example 2.

[0059] Test Example 1:

[0060] Test of flame retardancy performance:

[0061] Test method: The limiting oxygen index of the anti-aging polypropylene materials prepared in the examples and comparative examples was measured according to the standard G / T2406.2-2009. The results are shown in Table 1.

[0062] Table 1

[0063] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 30.7 Comparative Example 1 30.6 Example 2 30.8 Comparative Example 2 26.0 Example 3 31.2 Comparative Example 3 30.1

[0064] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the anti-aging polypropylene material prepared by the present invention has good flame retardancy performance.

[0065] In Comparative Example 2, the silica was not modified; by comparison, the flame retardancy performance of Examples 1 to 3 was better than that of Comparative Example 2, indicating that the pretreated silica with amino groups on the surface was grafted with polydichlorophosphazene. When the polyphosphazene decomposed by heat, non-combustible gases were generated, which could dilute the concentration of combustibles and isolate oxygen; at the same time, the generated phosphorus-containing free radicals could capture the active free radicals in the combustion chain reaction, effectively inhibiting the flame propagation; combined with the synergistic effect of phosphorus and nitrogen elements, the material was given high-efficiency flame retardancy performance.

[0066] Test Example 2:

[0067] Testing of mechanical properties:

[0068] Testing method: The test was carried out according to the standard of G / T 1040.2 - 2006. The examples and comparative examples were prepared into ISO527 - 2 standard specimens (Type 1A), and the tensile rate was 50 mm / min. The results are shown in Table 2.

[0069] Testing of anti - aging properties:

[0070] Testing method: The anti - aging polypropylene materials prepared in the examples and comparative examples were subjected to ultraviolet aging according to the standard of G / T16422.3 - 2014 for 240 h, and then subjected to thermal - oxidative aging according to the standard of G / T 7141 - 2008 by placing them in an oven at 100 °C for 168 h. The tensile strength was tested according to the mechanical property testing method, and the retention rate of tensile strength before and after aging was calculated. The results are shown in Table 2.

[0071] Table 2

[0072] Tensile strength (MPa) Tensile strength retention rate (%) Example 1 41.96 94.23 Example 2 42.14 94.76 Example 3 42.26 95.01 Comparative Example 1 31.61 70.32 Comparative Example 2 29.41 73.11 Comparative Example 3 30.77 76.23

[0073] From the comparison of the experimental data of Examples 1 - 3 and Comparative Examples 1 - 3 in Table 2, it can be found that the anti - aging polypropylene material prepared by the present invention has good mechanical properties and anti - aging properties.

[0074] The tensile strength of Examples 1 - 3 is greater than that of Comparative Examples 1 - 2, and the retention rate of tensile strength of Examples 1 - 3 is greater than that of Comparative Examples 1 - 3, indicating that starting from cyclopentadiene on the polypropylene side chain, a cycloaddition reaction with dichloroketene generates a tropolone structure; the tropolone contains a conjugated system of a carbonyl group and an enone group. This conjugated structure can absorb ultraviolet light through n→π* and π→π* electronic transitions, and convert the excited - state energy into heat energy through intramolecular energy transfer, thereby protecting the polymer molecular chain from photodegradation, and thus achieving the performance of anti - ultraviolet aging; the benzene ring on the silica contains a structure with adjacent amino and carboxyl groups, and a benzisoselenazolone structure is generated through diazonium salt coupling, acyl chlorination, and nucleophilic condensation cyclization reaction with 4 - (chloroethoxy)aniline. The selenium atom has a unique electronic structure, which can capture free radicals through single - electron transfer or hydrogen - atom transfer to terminate the oxidation chain reaction. The 4 - (chloroethoxy)aniline provides the conjugated system of the benzene ring to stabilize the reaction intermediate, and at the same time reduces steric hindrance, making the active site more accessible to free radicals, thereby improving the antioxidant performance; finally, the polypropylene and modified silica are mixed into a film to obtain an anti - aging polypropylene material. The hydroxyl group on the tropolone of the polypropylene side chain and the chlorine on the chloroethoxy group on the silica undergo an etherification reaction to form a cross - linked network between the polypropylene and the silica, thereby enhancing the mechanical properties of the material.

[0075] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A method for preparing an anti-aging polypropylene material, characterized in that: The method comprises the following preparation steps: (1) mixing polypropylene, cage silsesquioxane monomer, dicumyl peroxide and an additive, adding the mixture into a single screw extruder for melt blending to obtain silicone-modified polypropylene, wherein the melting temperature is 190-210° C.; (2) mixing organosilicon-modified polypropylene, tetrahydrofuran and ferric chloride in a mass ratio of 1:(20-30):(0.05-0.1) for 1 hour, cooling to -20°C, adding cyclopentadienyl lithium in an amount of 1.4-1.5 times the mass of organosilicon-modified polypropylene, heating to 0°C and continuing stirring for 12-14 hours, adding saturated ammonium chloride solution in an amount of 20-30 times the mass of organosilicon-modified polypropylene and stirring for 5-10 minutes, filtering, washing and drying to obtain pre-modified polypropylene; (3) reacting pre-modified polypropylene and dichloroethylene ketone to obtain modified polypropylene; (4) mixing pretreated silica and polydichlorophosphazene to obtain phosphorus-containing silica; mixing phosphorus-containing silica and sodium salt to obtain pre-modified silica; mixing pre-modified silica, sodium hydroxide and pure water to obtain aminocarboxyl silica; (5) Diazotizing aminocarboxyl silica to obtain diazo silica; diazotizing o-aminobenzoic acid to obtain a diazo solution; mixing selenium powder, potassium borohydride, and sodium hydroxide to obtain a selenium solution; mixing diazo silica, selenium solution, and diazo solution to obtain selenized silica; chlorinating the selenized modified silica to obtain chlorinated silica; reacting chlorinated silica with 4-(chloroethoxy)aniline to obtain modified silica; (6) Modified polypropylene, modified silica, pyridine, toluene, and tetrabutylammonium iodide are mixed in a mass ratio of 1:(0.1-0.15):(5-6):(30-40):0.01, refluxed at 100-110° C. for 20-30 min, and then dried in an oven at 180° C. to obtain an anti-aging polypropylene material.

2. The method for preparing an anti-aging polypropylene material according to claim 1, characterized in that: The preparation method of the cage-type silsesquioxane monomer in step (1) is as follows: bromobutyltrimethoxysilane and acetone are mixed, the temperature is raised to 50-60°C and stirred for 30-40min, pure water is added dropwise at a rate of 0.4mL / min, the mixture is heated to 70-80°C and refluxed for 24h, the mixture is cooled to room temperature and filtered, and the mixture is washed with acetone, pyridine, 1mol / L hydrochloric acid and pure water in sequence, and dried to obtain a precursor; the mass ratio of bromobutyltrimethoxysilane, acetone and pure water is 1:(5-7.5):(4.5-5); the precursor, tetrahydrofuran, N,N-diethylethylamine was mixed in a mass ratio of 1:(30-40):(15-20), heated to 65-70°C and stirred for 5-10 minutes, and 7-octenyltrimethoxysilane solution was added. The 7-octenyltrimethoxysilane solution was prepared using tetrahydrofuran and 7-octenyltrimethoxysilane with a mass of 1-1.5 times that of the precursor, and the concentration was 0.2 g / mL. The reflux reaction was continued for 24 hours. After the reaction was completed, it was cooled to room temperature, filtered, washed with 1 mol / L hydrochloric acid and pure water, and dried to obtain a cage-type silsesquioxane monomer.

3. The method for preparing an anti-aging polypropylene material according to claim 1, characterized in that: The mass ratio of the polypropylene, cage-type silsesquioxane monomer, dicumyl peroxide and auxiliary agent in step (1) is 1:(0.1-0.2):(0.001-0.002):(0.001-0.002); the polypropylene model is T30S, purchased from Sinopec Yangzi Petrochemical Co., Ltd.; and the auxiliary agent is antioxidant 1010.

4. The method for preparing an anti-aging polypropylene material according to claim 1, characterized in that: The preparation method of the modified polypropylene in step (3) is as follows: pre-modified polypropylene and tetrahydrofuran are mixed, dichloroethylene ketone is added dropwise at a rate of 0.1 mL / min at 0-5° C., triethylamine is added, the mixture is heated to room temperature and stirred for reaction for 5-6 hours, filtered and then added to a potassium acetate-glacial acetic acid solution, 98 wt% concentrated hydrochloric acid is added, the mixture is heated to 80-90° C. and refluxed for reaction for 24 hours, filtered, washed and dried to obtain the modified polypropylene; The mass ratio of pre-modified polypropylene, tetrahydrofuran, dichloroethylene ketone, triethylamine, potassium acetate-glacial acetic acid solution, and 98wt% concentrated hydrochloric acid is 1:(20-30):(1.4-1.5):(2.0-2.5):(40-50):(2-3); the potassium acetate-glacial acetic acid solution is obtained by mixing potassium acetate, glacial acetic acid, and pure water in a mass ratio of 1:5:

15.

5. The method for preparing an anti-aging polypropylene material according to claim 1, characterized in that: The preparation method of the aminocarboxyl silica in step (4) is as follows: silica, anhydrous ethanol, 3-aminopropyltrimethoxysilane and pure water are mixed in a mass ratio of 1: (20-25): (4.5-5.5): (10-12), heated to 70-80° C. for reaction for 5-6 hours, filtered, washed and dried to obtain pretreated silica; 2-amino-5-hydroxybenzoic acid methyl ester, di-tert-butyl dicarbonate and ethanol are mixed in a mass ratio of 1: (1.3-1.5): (50-60), reacted at 35-40° C. for 24 hours, and recrystallized from concentrated ethanol to obtain 2-tert-butoxycarbonylamino-5-hydroxybenzoic acid methyl ester; 2-tert-butoxycarbonylamino-5-hydroxybenzoic acid methyl ester, sodium hydride and tetrahydrofuran are mixed in a mass ratio of 1: (0.25-0.30): (10-12) Mix for 4-5 hours, filter and retain the supernatant to obtain sodium salt; mix pretreated silica, polydichlorophosphazene, triethylamine and tetrahydrofuran in a mass ratio of 1: (0.2-0.3): (2-3): (20-30), heat to 60-70°C and react for 10-12 hours, filter, wash and dry to obtain phosphorus-containing silica; under nitrogen protection, mix phosphorus-containing silica, sodium salt and dimethyl sulfoxide in a mass ratio of 1: (15-20): (20-30), heat to 115-120°C and react for 72 hours, filter, wash and dry to obtain pre-modified silica; mix pre-modified silica, sodium hydroxide and pure water in a mass ratio of 1: (0.3-0.5): (10-12), stir at 50-60°C for 4-5 hours, filter, wash and dry to obtain aminocarboxyl silica.

6. The method for preparing an anti-aging polypropylene material according to claim 1, characterized in that: The preparation method of the modified silicon dioxide in step (5) is as follows: mixing diazo silicon dioxide and selenium solution at 0-4°C for 30-40min, adding diazo solution, heating to 60-70°C and stirring for 3-4h, cooling to room temperature and stirring for 2-3h, adjusting the pH to 1-2 with 60wt% hydrochloric acid, filtering, washing and drying to obtain selenized silicon dioxide; mixing selenized modified silicon dioxide and thionyl chloride in a mass ratio of 1:(3-4), heating to 75-80°C and reflux reaction for 3-4h, filtering and drying to obtain acyl chloride dioxygen dioxide; Silicon dioxide; the mass ratio of diazo silicon dioxide, diazo solution and selenium solution is 1:(5-6):(200-250); 4-(chloroethoxy)aniline, sodium bicarbonate, pure water and ether are mixed, cooled to 0-5°C, silicon dioxide chloride is added, the temperature is raised to room temperature for reaction for 4-5h, filtered, washed and dried to obtain modified silicon dioxide; the mass ratio of silicon dioxide chloride, 4-(chloroethoxy)aniline, sodium bicarbonate, pure water and ether is 1:(5-6):(2-2.5):(5-6):(20-30).

7. The method for preparing an anti-aging polypropylene material according to claim 6, characterized in that: The preparation method of the diazo silicon dioxide is as follows: aminocarboxyl silicon dioxide, pure water, and 98wt% concentrated hydrochloric acid are mixed in a mass ratio of 1:(5-6):(5-6), cooled to 0-4°C, 0.5g / mL sodium nitrite solution with a volume of 0.8-1.0 times that of pure water is added, stirred for 1-2h, and filtered to obtain diazo silicon dioxide; the preparation method of the diazo solution is as follows: o-aminobenzoic acid, pure water, and 98wt% concentrated hydrochloric acid are mixed in a mass ratio of 1:(1.4-1.6):(1.4-1.6), cooled to 0-4°C, 0.8-1.0 times the volume of pure water is added, and the mixture is stirred for 1-2h, and the mixture is filtered to obtain diazo silicon dioxide; 0.5g / mL sodium nitrite solution, stirring for 1-2h to obtain a diazo solution; the preparation method of the selenium solution is: under nitrogen protection, 1 / 3 of the total amount of selenium powder, pure water, and 0.18g / mL potassium borohydride solution are mixed for 20-30min, the remaining selenium powder is added, and stirring is continued for 30-40min, and 0.4g / mL sodium hydroxide solution is added to obtain a selenium solution; the mass ratio of selenium powder, pure water, 0.18g / mL potassium borohydride solution, and 0.4g / mL sodium hydroxide solution is 1:(20-30):(20-30):(20-30).

8. An anti-aging polypropylene material prepared according to the method for preparing the anti-aging polypropylene material according to any one of claims 1 to 7.