Functionalized silicon dioxide modified polypropylene flame-retardant plastic and preparation method thereof

Abstract

The invention relates to the technical field of polypropylene plastics, and discloses a functional silicon dioxide modified polypropylene flame-retardant plastic, compared with the traditional polypropylene plastic, the polypropylene plastic modified by adding thiazolyl spiro phosphoryl silicon dioxide has better mechanical property and flame-retardant property, after the silicon dioxide is added into the polypropylene matrix, the mechanical property of the polypropylene plastic is improved, the silicon dioxide and the phosphorus-containing flame retardant have a synergistic effect, the flame retardance of the polypropylene plastic is improved, and the nitrogen-sulfur-containing flame retardant grafted on the silicon dioxide has a synergistic effect with the silicon dioxide and the phosphorus-containing flame retardant during combustion, so that the flame retardance of the polypropylene plastic is improved. And in addition, the micromolecular flame retardant is grafted on the surface of the silicon dioxide, so that the flame retardant loss behavior caused by precipitation is reduced, and the flame-retardant stability of the polypropylene is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene plastics, in particular to a functionalized silicon dioxide modified polypropylene flame retardant plastic and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is considered an important polymer material due to its easy processing, high chemical resistance and good stability. Therefore, polypropylene is widely used in building materials, transportation, electrical engineering, medical equipment and other fields. However, polypropylene is a linear thermoplastic polymer that is relatively easy to burn. During the combustion process, molten droplets will be produced and a large amount of heat and toxic smoke will be released, which has caused a large number of fire-related accidents, which limits its wider application areas. Therefore, flame retardant modification of polypropylene plastics has become an important direction to expand its application.

[0003] In order to improve the flame retardancy of polypropylene plastics, researchers have done a lot of research, including the Chinese patent publication number CN103467852B, which discloses a polypropylene flame retardant plastic, and the Chinese patent publication number CN1252170C, which discloses a halogen-free flame retardant polypropylene material. Although both improve the flame retardancy of polypropylene plastics, they still have the problem of large addition amount and unsatisfactory flame retardant effect. Phosphorus-containing flame retardants, such as red phosphorus and phosphates, are considered to be one of the best substitutes for halogen-containing flame retardants. During the combustion process, the flame retardant effect is mainly achieved through the condensed phase and the gas phase. Nitrogen-sulfur flame retardants are synergists of phosphorus-containing flame retardants. By increasing the release of non-flammable gases during the combustion process, the flame retardancy of the effective matrix is ​​improved. However, small molecule flame retardants are prone to precipitation and other behaviors that reduce the flame retardant effect during use. Grafting them on the surface of inorganic substances is an important method to reduce this behavior. Nano-silicon dioxide is a non-toxic and safe white powdery substance with a mesh structure, which can be used as a carrier of flame retardants to produce a synergistic effect and improve the flame retardant effect. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a functionalized silica-modified polypropylene flame-retardant plastic and a preparation method thereof, which solves the problems of low mechanical properties and poor flame retardancy of traditional polypropylene plastics.

[0005] To achieve the above object, the present invention provides the following technical solution: a functionalized silica-modified polypropylene flame-retardant plastic, wherein the preparation method of the functionalized silica-modified polypropylene flame-retardant plastic comprises the following steps: (1) According to the mass fraction of silica being 100 parts, toluene being 2500-6000 parts, and m-phenylenedimethyl isocyanate being 15-30 parts, the silica is ultrasonically dispersed in a toluene solvent, and then m-phenylenedimethyl isocyanate is added, and the mixture is stirred evenly under a nitrogen atmosphere, and reacted at 60-100° C. for 0.5-2 h. After the reaction is completed, the mixture is cooled, filtered, and washed with ethanol to obtain isocyanate-based silica; (2) ultrasonically dispersing isocyanate-based silica in an acetone solvent, then adding dibutyltin dilaurate and propylene oxide, stirring evenly, and reacting. After the reaction is completed, filtering, and washing with ethanol to obtain epoxidized silica; (3) placing epoxidized silicon dioxide, spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and catalyst titanium tetrachloride in a reaction container, stirring evenly, and reacting, after the reaction is completed, filtering, and washing with ethanol to obtain spirocyclic phosphoryl chloride-based silicon dioxide; (4) dissolving 2-aminothiazole and triethylamine (TEA) in dichloromethane, stirring evenly, adding spirocyclic phosphoryl chloride-based silica, and refluxing to react. After the reaction is completed, filtering, washing with saturated sodium bicarbonate solution and deionized water, respectively, to obtain thiazolyl spirocyclic phosphoryl silica; (5) Add polypropylene particles, thiazolyl spirocyclic phosphosilyl silica, plasticizer triethyl citrate and antioxidant BHA into a high-speed mixer and mix them evenly, then extrude them at 160-200° C. using a twin-screw extruder, and finally shape them using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic.

[0006] Preferably, in step (2), the mass fraction of isocyanate-based silicon dioxide is 100 parts, the mass fraction of acetone is 1500-4000 parts, the mass fraction of dibutyltin dilaurate is 0.5-3 parts, and the mass fraction of glycidol is 12-30 parts.

[0007] Preferably, in step (2), the reaction temperature is 35-60° C. and the reaction time is 3-8 h.

[0008] Preferably, in step (3), the mass fraction of epoxidized silicon dioxide is 100 parts, the mass fraction of spirocyclic phosphoryl dichloride is 25-60 parts, and the mass fraction of titanium tetrachloride is 0.04-0.1 parts.

[0009] Preferably, in step (3), the reaction temperature is 40-70° C. and the reaction time is 2-6 h.

[0010] Preferably, in step (4), the mass fraction of 2-aminothiazole is 15-40 parts, triethylamine is 18-50 parts, dichloromethane is 1200-3000 parts, and spirocyclic phosphoryl chloride-based silicon dioxide is 100 parts.

[0011] Preferably, in step (4), the reaction temperature is 20-40° C. and the reaction time is 6-15 h.

[0012] Preferably, in the step (5), the mass fraction of the polypropylene particles is 100 parts, the mass fraction of the thiazolyl spirocyclic phosphosilane silica is 2-6 parts, the mass fraction of triethyl citrate is 0.5-2 parts, and the mass fraction of BHA is 0.8-3 parts.

[0013] Compared with the prior art, the present invention has the following experimental principles and beneficial technical effects: The functionalized silica-modified polypropylene flame-retardant plastic comprises the following steps: firstly, silica is modified by using m-phenylenedimethyl isocyanate to obtain isocyanate-based silica; then, dibutyltin dilaurate is used as a catalyst to make the isocyanate of the isocyanate-based silica react with the hydroxyl group of glycidol to obtain epoxidized silica; then, titanium tetrachloride is used as a catalyst to make the chlorine atom of spirocyclic phosphoryl dichloride react with the epoxy group of epoxidized silica to obtain spirocyclic phosphoryl chloride-based silica; then, triethylamine is used as an acid-binding agent to make the amino group of 2-aminothiazole react with the chlorine atom of spirocyclic phosphoryl chloride-based silica to obtain thiazolyl spirocyclic phosphoryl silica; finally, polypropylene is used as a matrix and thiazolyl spirocyclic phosphoryl silica is used as a flame-retardant modifier to prepare the functionalized silica-modified polypropylene flame-retardant plastic.

[0014] The functionalized silica-modified polypropylene flame-retardant plastic has better mechanical properties and flame-retardant properties than traditional polypropylene plastics. After adding thiazolyl spirocyclic phosphoryl silica, the modified polypropylene plastic has better mechanical properties and flame-retardant properties. After adding silica to the polypropylene matrix, the dispersibility of the modified silica is significantly improved, so that it is evenly dispersed inside the polypropylene plastic, thereby forming a new structure with excellent peeling state, improving the stress dispersion behavior of the polypropylene material when subjected to external force, avoiding damage caused by stress concentration, and silica can promote heterogeneous nucleation behavior during polypropylene crystallization, improve the crystallinity of polypropylene, and increase the mechanical properties of polypropylene plastics. There is a synergistic effect between silica and phosphorus-containing flame retardants. When heated, it can decompose with the phosphorus-containing flame retardants into phosphoric acid substances. The silicon dioxide and the phosphorus-containing flame retardant react to form heat-resistant silicon-aluminum-phosphate substances, which significantly increase the antioxidant and heat-resistant properties of the carbon layer when attached to the surface of the carbon layer, and further increase the compactness of the carbon layer, thereby improving the residual carbon rate of polypropylene plastics and reducing the heat release rate of polypropylene during combustion. In addition, the nitrogen-sulfur flame retardant grafted on the silicon dioxide can release a large amount of flame-retardant gases such as water vapor, nitrogen, and sulfur dioxide when burning, which can dilute the concentration of oxygen and other flammable volatiles in the air and cool the combustibles to achieve the purpose of stopping combustion, thereby synergizing with the silicon dioxide and the phosphorus-containing flame retardant to further increase the flame retardancy of polypropylene. In addition, the small molecule flame retardant is grafted on the surface of the silicon dioxide to reduce the loss of the flame retardant due to precipitation and increase the flame retardant stability of polypropylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the reaction formula between epoxidized silicon dioxide and spirocyclic phosphoryl dichloride; Figure 2 It is the reaction formula between 2-aminothiazole and spirocyclic phosphoryl chloride-based silica. DETAILED DESCRIPTION

[0016] To achieve the above object, the present invention provides the following specific implementation methods and examples: A functionalized silica-modified polypropylene flame-retardant plastic, the preparation method of which comprises the following steps: (1) According to the mass fraction of silica being 100 parts, toluene being 2500-6000 parts, and m-phenylenedimethyl isocyanate being 15-30 parts, the silica is ultrasonically dispersed in a toluene solvent, and then m-phenylenedimethyl isocyanate is added, and the mixture is stirred evenly under a nitrogen atmosphere, and reacted at 60-100° C. for 0.5-2 h. After the reaction is completed, the mixture is cooled, filtered, and washed with ethanol to obtain isocyanate-based silica; (2) According to the mass fraction of isocyanate silica being 100 parts, acetone being 1500-4000 parts, dibutyltin dilaurate being 0.5-3 parts, and glycidol being 12-30 parts, isocyanate silica is ultrasonically dispersed in acetone solvent, and then dibutyltin dilaurate and glycidol are added, stirred evenly, reacted at 35-60° C. for 3-8 hours, filtered after the reaction is completed, and washed with ethanol to obtain epoxidized silica; (3) According to the mass fraction of epoxidized silicon dioxide being 100 parts, spirocyclic phosphoryl chloride having the molecular formula of C5H8Cl2O6P2 being 25-60 parts, and titanium tetrachloride being 0.04-0.1 parts, epoxidized silicon dioxide, spirocyclic phosphoryl chloride and catalyst titanium tetrachloride are placed in a reaction vessel, stirred evenly, reacted at 40-70° C. for 2-6 hours, filtered after the reaction is completed, and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silicon dioxide; (4) Dissolve 2-aminothiazole and triethylamine (TEA) in dichloromethane according to the mass fraction of 15-40 parts of 2-aminothiazole, 18-50 parts of triethylamine, 1200-3000 parts of dichloromethane, and 100 parts of spirophosphoryl chloride-based silica. After stirring evenly, add spirophosphoryl chloride-based silica, and reflux at 20-40° C. for reaction for 6-15 hours. After the reaction is completed, filter, wash with saturated sodium bicarbonate solution and deionized water respectively to obtain thiazolyl spirophosphoryl chloride-based silica; (5) According to the mass fraction of polypropylene particles being 100 parts, thiazolyl spirocyclic phosphyl silica being 2-6 parts, triethyl citrate being 0.5-2 parts, and BHA being 0.8-3 parts, polypropylene particles, thiazolyl spirocyclic phosphyl silica, plasticizer triethyl citrate and antioxidant BHA are added into a high-speed mixer and mixed evenly, and then extruded at 160-200° C. using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic. Example 1

[0017] (1) 5 g of silica was ultrasonically dispersed in 125 g of toluene solvent, and then 0.75 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 60 °C for 0.5 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) 4 g of isocyanate-based silica was ultrasonically dispersed in 60 g of acetone solvent, and then 0.02 g of dibutyltin dilaurate and 0.48 g of glycidol were added, stirred evenly, and reacted at 35 °C for 3 h. After the reaction was completed, the mixture was filtered and washed with ethanol to obtain epoxidized silica; (3) 4 g of epoxidized silica, 1 g of spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and 0.0016 g of catalyst titanium tetrachloride are placed in a reaction container, stirred evenly, reacted at 40°C for 2 h, and after the reaction is completed, filtered and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silica; (4) Dissolve 0.3 g of 2-aminothiazole and 0.36 g of triethylamine (TEA) in 24 g of dichloromethane, stir evenly, add 2 g of spirocyclic phosphoryl chloride-based silica, and reflux at 20°C for 6 h. After the reaction is completed, filter, and wash with saturated sodium bicarbonate solution and deionized water respectively to obtain thiazolyl spirocyclic phosphoryl silica; (5) 8 g of polypropylene particles, 0.16 g of thiazolyl spirocyclic phosphinoyl silica, 0.04 g of plasticizer triethyl citrate and 0.064 g of antioxidant BHA were added into a high-speed mixer and mixed evenly, then extruded at 160 °C using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic. Example 2

[0018] (1) 5 g of silica was ultrasonically dispersed in 150 g of toluene solvent, and then 0.9 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 70 °C for 0.8 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) 4 g of isocyanate-based silica was ultrasonically dispersed in 80 g of acetone solvent, and then 0.04 g of dibutyltin dilaurate and 0.6 g of propylene oxide were added, stirred evenly, and reacted at 40 ° C for 4 h. After the reaction was completed, it was filtered and washed with ethanol to obtain epoxidized silica; (3) 4 g of epoxidized silica, 1.2 g of spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and 0.002 g of catalyst titanium tetrachloride are placed in a reaction container, stirred evenly, reacted at 45°C for 3 h, and after the reaction is completed, filtered and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silica; (4) Dissolve 0.4 g of 2-aminothiazole and 0.4 g of triethylamine (TEA) in 30 g of dichloromethane, stir evenly, add 2 g of spirocyclic phosphoryl chloride-based silica, and reflux at 25°C for 8 h. After the reaction is completed, filter, wash with saturated sodium bicarbonate solution and deionized water respectively, to obtain thiazolyl spirocyclic phosphoryl silica; (5) 8 g of polypropylene particles, 0.24 g of thiazolyl spirocyclic phosphinoyl silica, 0.06 g of plasticizer triethyl citrate and 0.08 g of antioxidant BHA were added into a high-speed mixer and mixed evenly, then extruded at 170 °C using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic. Example 3

[0019] (1) 5 g of silica was ultrasonically dispersed in 180 g of toluene solvent, and then 1.2 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 80 °C for 1.2 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) 4 g of isocyanate-based silica was ultrasonically dispersed in 110 g of acetone solvent, and then 0.07 g of dibutyltin dilaurate and 0.8 g of propylene oxide were added, stirred evenly, and reacted at 45 ° C for 5 h. After the reaction was completed, it was filtered and washed with ethanol to obtain epoxidized silica; (3) 4 g of epoxidized silica, 1.7 g of spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and 0.003 g of catalyst titanium tetrachloride were placed in a reaction container, stirred evenly, reacted at 55°C for 4 h, and after the reaction was completed, filtered and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silica; (4) Dissolve 0.55 g of 2-aminothiazole and 0.64 g of triethylamine (TEA) in 40 g of dichloromethane, stir evenly, add 2 g of spirocyclic phosphoryl chloride-based silica, and reflux at 30°C for 10 h. After the reaction is completed, filter, wash with saturated sodium bicarbonate solution and deionized water respectively, to obtain thiazolyl spirocyclic phosphoryl silica; (5) 8 g of polypropylene particles, 0.3 g of thiazolyl spirocyclic phosphinoyl silica, 0.09 g of plasticizer triethyl citrate and 0.14 g of antioxidant BHA were added into a high-speed mixer and mixed evenly, then extruded at 180 °C using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic. Example 4

[0020] (1) 5 g of silica was ultrasonically dispersed in 280 g of toluene solvent, and then 1.4 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 90 °C for 1.8 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) Ultrasonic dispersion of 4 g of isocyanate-based silica in 140 g of acetone solvent, and then adding 0.1 g of dibutyltin dilaurate and 1 g of glycidol, stirring evenly, and reacting at 55 °C for 7 h. After the reaction is completed, filtering, washing with ethanol, and obtaining epoxidized silica; (3) 4 g of epoxidized silica, 2 g of spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and 0.0032 g of catalyst titanium tetrachloride were placed in a reaction container, stirred evenly, reacted at 60°C for 5 h, and after the reaction was completed, filtered and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silica; (4) Dissolve 0.7 g of 2-aminothiazole and 0.7 g of triethylamine (TEA) in 50 g of dichloromethane, stir evenly, add 2 g of spirocyclic phosphoryl chloride-based silica, and reflux at 35°C for 12 h. After the reaction is completed, filter, wash with saturated sodium bicarbonate solution and deionized water respectively, to obtain thiazolyl spirocyclic phosphoryl silica; (5) 8 g of polypropylene particles, 0.4 g of thiazolyl spirocyclic phosphinoyl silica, 0.14 g of plasticizer triethyl citrate and 0.2 g of antioxidant BHA were added into a high-speed mixer and mixed evenly, then extruded at 190 °C using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic. Example 5

[0021] (1) 5 g of silica was ultrasonically dispersed in 300 g of toluene solvent, and then 1.5 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 100 °C for 2 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) 4 g of isocyanate-based silica was ultrasonically dispersed in 160 g of acetone solvent, and then 0.12 g of dibutyltin dilaurate and 1.2 g of propylene oxide were added, stirred evenly, and reacted at 60 ° C for 8 h. After the reaction was completed, it was filtered and washed with ethanol to obtain epoxidized silica; (3) 4 g of epoxidized silica, 2.4 g of spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and 0.004 g of catalyst titanium tetrachloride were placed in a reaction container, stirred evenly, reacted at 70°C for 6 h, and after the reaction was completed, filtered and washed with ethanol to obtain spirocyclic phosphoryl chloride-based silica; (4) Dissolve 0.8 g of 2-aminothiazole and 1 g of triethylamine (TEA) in 60 g of dichloromethane, stir evenly, add 2 g of spirocyclic phosphoryl chloride-based silica, and reflux at 40°C for 15 h. After the reaction is completed, filter, wash with saturated sodium bicarbonate solution and deionized water respectively, to obtain thiazolyl spirocyclic phosphoryl silica; (5) 8 g of polypropylene particles, 0.48 g of thiazolyl spirocyclic phosphinoyl silica, 0.16 g of plasticizer triethyl citrate and 0.24 g of antioxidant BHA were added into a high-speed mixer and mixed evenly, then extruded at 200 °C using a twin-screw extruder, and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic.

[0022] Comparative Example 1 (1) 5 g of silica was ultrasonically dispersed in 200 g of toluene solvent, and then 1 g of m-xylylene diisocyanate was added. The mixture was stirred evenly under a nitrogen atmosphere and reacted at 80 °C for 1 h. After the reaction was completed, the mixture was cooled, filtered, and washed with ethanol to obtain isocyanate-based silica. (2) 4 g of isocyanate-based silica was ultrasonically dispersed in 100 g of acetone solvent, and then 0.08 g of dibutyltin dilaurate and 0.8 g of propylene oxide were added, stirred evenly, and reacted at 50 ° C for 5 h. After the reaction was completed, it was filtered and washed with ethanol to obtain epoxidized silica; (3) 8 g of polypropylene particles, 0.4 g of epoxidized silica, 0.08 g of plasticizer triethyl citrate and 0.08 g of antioxidant BHA were added into a high-speed mixer and mixed evenly. The mixture was then extruded at 180 °C using a twin-screw extruder and finally shaped using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic.

[0023] The heat release rate (HRR) and carbon residue rate of functionalized silica modified polypropylene flame retardant plastics were tested in accordance with the national standard GB / T 12670-2008.

[0024]

[0025] The flexural strength of functionalized silica modified polypropylene flame retardant plastic was tested in accordance with the national standard GB / T 34870.1-2017.

[0026]

Claims

1. A functionalized silica-modified polypropylene flame-retardant plastic, characterized in that: The preparation method of the functionalized silica-modified polypropylene flame-retardant plastic comprises the following steps: (1) According to the mass fraction of silica being 100 parts, toluene being 2500-6000 parts, and m-phenylenedimethyl isocyanate being 15-30 parts, the silica is ultrasonically dispersed in a toluene solvent, and then m-phenylenedimethyl isocyanate is added, and the mixture is stirred evenly under a nitrogen atmosphere, and reacted at 60-100° C. for 0.5-2 hours. After the reaction is completed, isocyanate-based silica is obtained; (2) ultrasonically dispersing isocyanate-based silica in an acetone solvent, then adding dibutyltin dilaurate and glycidol, stirring evenly, and reacting. After the reaction is completed, epoxidized silica is obtained; (3) placing epoxidized silicon dioxide, spirocyclic phosphoryl chloride with a molecular formula of C5H8Cl2O6P2 and catalyst titanium tetrachloride in a reaction container, stirring them evenly, and reacting them. After the reaction is completed, spirocyclic phosphoryl chloride-based silicon dioxide is obtained; (4) dissolving 2-aminothiazole and triethylamine in dichloromethane, stirring evenly, adding spirocyclic phosphoryl chloride-based silica, and refluxing to react. After the reaction is completed, thiazolyl spirocyclic phosphoryl silica is obtained; (5) Add polypropylene particles, thiazolyl spirocyclic phosphosilyl silica, plasticizer triethyl citrate and antioxidant BHA into a high-speed mixer and mix them evenly, then extrude them at 160-200° C. using a twin-screw extruder, and finally shape them using an injection molding machine to obtain a functionalized silica-modified polypropylene flame-retardant plastic.

2. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (2), the mass fraction of isocyanate-based silicon dioxide is 100 parts, the mass fraction of acetone is 1500-4000 parts, the mass fraction of dibutyltin dilaurate is 0.5-3 parts, and the mass fraction of glycidol is 12-30 parts.

3. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (2), the reaction temperature is 35-60° C. and the reaction time is 3-8 h.

4. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (3), the mass fraction of epoxidized silicon dioxide is 100 parts, the mass fraction of spirocyclic phosphoryl dichloride is 25-60 parts, and the mass fraction of titanium tetrachloride is 0.04-0.1 parts.

5. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (3), the reaction temperature is 40-70° C. and the reaction time is 2-6 h.

6. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (4), the mass fraction of 2-aminothiazole is 15-40 parts, the mass fraction of triethylamine is 18-50 parts, the mass fraction of dichloromethane is 1200-3000 parts, and the mass fraction of spirocyclic phosphoryl chloride-based silicon dioxide is 100 parts.

7. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (4), the reaction temperature is 20-40° C. and the reaction time is 6-15 h.

8. The functionalized silica-modified polypropylene flame-retardant plastic according to claim 1, characterized in that: In the step (5), the mass fraction of the polypropylene particles is 100 parts, the mass fraction of the thiazolyl spirocyclic phosphosilyl silica is 2-6 parts, the mass fraction of triethyl citrate is 0.5-2 parts, and the mass fraction of BHA is 0.8-3 parts.

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