High-strength polypropylene reinforced composite pipe and preparation method thereof

Abstract

The invention relates to the field of composite pipes, and discloses a high-strength polypropylene reinforced composite pipe and a preparation method thereof.The composite pipe comprises a pipe and a profile plastic pipe, and the profile plastic pipe is obtained by conducting melt extrusion, cooling and shaping on a pipe composition through a double-screw extruder; the pipe composition comprises polypropylene, a composite filler, modified glass fibers, a high-molecular compatilizer, a lubricant and an antioxidant, the composite filler is prepared by attaching nano silicon dioxide particles to the surface of a layered vermiculite sheet through a chemical reaction; the modified glass fiber is prepared by modifying an anti-aging component and a flame-retardant component on the surface of carboxylated glass fiber through a chemical reaction, the anti-aging component is prepared by reacting glycidyl ether with p-phenylenediamine, and the flame-retardant component is prepared by reacting 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with octenyl succinic anhydride. By adding the composite filler and the modified glass fiber, the pipe is endowed with excellent heat resistance, flame retardance, high-temperature aging resistance and mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of composite pipes, and in particular relates to a high-strength polypropylene reinforced composite pipe and a preparation method thereof. Background Art

[0002] Industrial pipelines require long service life and heat resistance, especially in applications with a constant temperature of 40~60℃ or a temperature peak of up to 80℃, such as large-diameter pipelines in power plants, thermal fluid transmission pipelines, and geothermal pipelines, which have higher requirements for materials. Polypropylene pipes have many advantages such as light weight, corrosion resistance, long service life, easy installation, and reliable connection. In recent years, they have received more and more attention and have a high market share. However, the existing polypropylene materials have limited heat resistance and flame retardancy, are sensitive to environmental stress, and are greatly affected by factors such as temperature, loading speed, and loading time. They are prone to high-temperature aging in high-temperature environments, which seriously affects the safety of pipelines in transporting high-temperature liquids. Summary of the invention

[0003] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a high-strength polypropylene reinforced composite pipe and a preparation method thereof, by adding composite fillers and modified glass fibers, the pipe is endowed with excellent heat resistance, flame retardancy, high temperature aging resistance and mechanical properties.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A high-strength polypropylene reinforced composite pipe, comprising a pipe and a profile plastic pipe spirally wound and bonded to the outer surface of the pipe, wherein the interior of the profile plastic pipe is a hollow structure, and two sheets are provided inside the profile plastic pipe, and the two sheets separate the profile plastic pipe into two hollow pipes, and the outer wall of the pipe and the end face of the profile plastic pipe away from the outer wall of the pipe are both provided with embedded steel wires, and reinforcing ribs are equidistantly provided between the profile plastic pipes along the circumferential direction of the pipe; The profile plastic pipe is obtained by melting and extruding the pipe composition through a twin-screw extruder and cooling and shaping; the pipe composition comprises the following raw materials in parts by weight: 100 parts of polypropylene, 3-8 parts of composite filler, 5-20 parts of modified glass fiber, 2-8 parts of polymer compatibilizer, 1-3 parts of lubricant, and 0.05-5 parts of antioxidant; The composite filler is made by attaching nano silicon dioxide particles to the surface of layered vermiculite sheets by using sol-gel method and 3-aminopropyltriethoxysilane; the modified glass fiber is made by modifying the anti-aging component and the flame retardant component on the surface of the carboxylated glass fiber by chemical reaction, wherein the anti-aging component is made by ring-opening reaction of glycidyl ether and p-phenylenediamine, and the flame retardant component is made by addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and octenyl succinic anhydride.

[0005] Preferably, the polymer compatibilizer is one or more combinations of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polyethylene, acrylic acid grafted polyethylene, silane grafted polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-acrylate copolymer, and ethylene acrylic acid copolymer.

[0006] Preferably, the lubricant is one of polyethylene wax and oxidized polyethylene wax; the antioxidant is one or more combinations of antioxidant DLTP, antioxidant 168, antioxidant 1010, antioxidant 1076, antioxidant 3114, and antioxidant 1024.

[0007] Preferably, the method for preparing the composite filler comprises the following steps: (1) taking expanded vermiculite and dispersing it uniformly in a mixed solution of concentrated sulfuric acid and concentrated nitric acid by ultrasonication, placing it under reflux reaction at 110-125°C for 4-6 hours, and washing, drying and grinding it after the reaction is completed to prepare acidified layered vermiculite flakes; (2) Acidified layered vermiculite flakes were ultrasonically dispersed in a mixed solution of ethanol and deionized water, and ammonia water was added to adjust the pH value of the system to 8-9 to obtain a suspension. Tetraethyl silicate was dissolved in anhydrous ethanol and added to the suspension, ultrasonically dispersed evenly, and then stirred for 16-18 hours to obtain a dispersion. 3-aminopropyltriethoxysilane was dissolved in a mixed solution of ethanol and acetic acid, and then added to the dispersion and stirred for reaction for 5-7 hours. After the reaction was completed, the composite filler was prepared by centrifugation, washing, and drying.

[0008] Preferably, the method for preparing the modified glass fiber comprises the following steps: A. Put glycidyl ether and p-phenylenediamine in a reactor, add toluene solvent, place at 95-105°C and stir to react for 10-12 hours. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and prepare an anti-aging component; B. 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and octenyl succinic anhydride are placed in a reactor, tetrahydrofuran solvent is added, and the mixture is stirred at 45-60° C. for 5-7 hours. After the reaction is completed, the mixture is subjected to rotary evaporation, washing, and drying to prepare a flame retardant component; C. Put the anti-aging component and the flame retardant component into a reactor, add N,N-dimethylformamide solvent, stir and react at 60-85°C for 6-12h, filter, wash and dry after the reaction to obtain a functional modifier; D. Ultrasonic dispersion of carboxylated glass fiber in deionized water, adding functional modifier and stirring to mix, adjusting the pH value of the system to 7-9 with sodium carbonate solution, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide and stirring to react for 4-6 hours, after the reaction is completed, filtering and drying to prepare modified glass fiber.

[0009] Preferably, in step A, the molar ratio of glycidyl ether to p-phenylenediamine is 1:3-3.4.

[0010] Preferably, in step B, the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to octenylsuccinic anhydride is 1:1-1.2.

[0011] Preferably, the molar ratio of the anti-aging component to the flame retardant component in step C is 1:2-2.5.

[0012] Preferably, the method for preparing the carboxylated glass fiber in step D comprises the following steps: D1. Take the glass fiber and place it in an acetone solution for ultrasonic treatment and immersion to remove the impregnated material on the surface of the glass fiber. After drying, soak it in a mixed solution of concentrated sulfuric acid and hydrogen peroxide and stir for 8 to 12 hours to prepare a pretreated glass fiber; D2, immersing the pretreated glass fiber in a toluene solution of 3-aminopropyltriethoxysilane and condensing and refluxing at 105-115° C. for 8-12 hours, and after the reaction is completed, repeatedly washing with toluene and drying to prepare an amino glass fiber; D3. Take the amino glass fiber and ultrasonically disperse it in N, N-dimethylformamide, add succinic anhydride and stir to mix, place it at 55-70°C and stir to react for 20-24 hours. After the reaction is completed, wash and dry to prepare carboxylated glass fiber.

[0013] The method for preparing the high-strength polypropylene reinforced composite pipe as described above comprises the following steps: S1, taking parts by weight of polypropylene, composite filler, modified glass fiber, polymer compatibilizer, lubricant and antioxidant and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Embedded steel wires are arranged on the outer wall of the pipe and the end face of the profile plastic pipe away from the outer wall of the pipe, and reinforcing ribs are spirally wound along the profile plastic pipes and bonded to the outer surface of the pipe to prepare a high-strength polypropylene reinforced composite pipe.

[0014] Beneficial effects of the present invention: The present invention uses polypropylene material as a base material, adds a composite filler and a modified glass fiber functional component, and gives the pipe excellent heat resistance, flame retardancy, high temperature aging resistance and mechanical properties. The present invention uses concentrated sulfuric acid and concentrated nitric acid to acidify the expanded vermiculite to activate the surface groups of the expanded vermiculite, then uses tetraethyl silicate as a silicon source, uses a sol-gel method to obtain a mixed system of layered vermiculite sheets and nano-silicon dioxide, then uses 3-aminopropyltriethoxysilane to couple the nano-silicon dioxide and the layered vermiculite sheets, and the nano-silicon dioxide particles are attached to the surface of the layered vermiculite sheets to prepare a composite filler. The composite material has good dispersibility in the matrix and has a strong interface interaction with the matrix, which greatly improves the comprehensive performance of the pipe and gives the pipe excellent high temperature resistance and mechanical properties.

[0015] The invention uses glycidyl ether and an antioxidant p-phenylenediamine to undergo a ring-opening reaction to prepare an anti-aging component, wherein a plurality of epoxy groups in the glycidyl ether structure can be provided for a grafting reaction with p-phenylenediamine to generate a plurality of anti-aging functional groups -NH, thereby enhancing the aging protection effect of the antioxidant. At the same time, the invention uses a PH bond in a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide structure to undergo an addition reaction with octenyl succinic anhydride to prepare a flame retardant component, and then uses an amino group in the anti-aging component structure to undergo a grafting reaction with an acid anhydride group in the flame retardant component structure to prepare a functional modifier. In addition, the invention uses concentrated sulfuric acid and hydrogen peroxide to fully expose the silanol groups on the surface of the glass fiber, and then Then, carboxylated glass fiber is prepared by using 3-aminopropyltriethoxysilane and succinic anhydride, and the carboxylated glass fiber is modified by using a functional modifier, so that the carboxylated glass fiber and the functional modifier undergo an amidation reaction to prepare modified glass fiber. After the glass fiber is surface-modified by the anti-aging component and the flame-retardant component, the surface lipophilicity is improved, which promotes the glass fiber to be relatively evenly dispersed in the matrix, and to a certain extent avoids the performance defects caused by glass fiber agglomeration. In addition, the functional modifier is grafted to the surface of the glass fiber through a strong chemical bond, which can not only play a good high-temperature aging resistance and flame retardant effect, but also does not have the problem of migration and seepage, ensuring that the pipe achieves long-term high-temperature aging resistance and flame retardant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a schematic cross-sectional view of the high-strength polypropylene reinforced composite pipe of the present invention; Figure 2It is a structural schematic diagram of the high-strength polypropylene reinforced composite pipe of the present invention.

[0018] In the figure: 1- pipe, 2- profile plastic pipe, 3- sheet, 4- reinforcing rib, 5- hollow tube, 6- embedded steel wire. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The melt index of the copolymerized polypropylene in the examples and comparative examples of the present invention is 0.5 g / 10 min (230° C., 2.16 Kg).

[0021] like Figure 1-2 As shown, a high-strength polypropylene reinforced composite pipe comprises a pipe 1 and a profile plastic pipe 2 spirally wound and bonded to the outer surface of the pipe 1, the interior of the profile plastic pipe 2 is a hollow structure, and two sheets 3 fitted to each other are arranged inside the profile plastic pipe 2, and the two sheets 3 separate the profile plastic pipe 2 into two hollow pipes 5, the outer wall of the pipe 1 and the end face of the profile plastic pipe 2 away from the outer wall of the pipe 1 are both provided with embedded steel wires 6, and reinforcing ribs 4 are equidistantly arranged between the profile plastic pipes 2 along the circumferential direction of the pipe 1.

[0022] Embodiment 1 A method for preparing a composite filler comprises the following steps: (1) 5 g of expanded vermiculite was uniformly dispersed in a mixed solution of 120 mL of concentrated sulfuric acid and 40 mL of concentrated nitric acid by ultrasonication, and the mixture was refluxed at 120° C. for 5 h. After the reaction was completed, the mixture was washed, dried, and ground to obtain acidified layered vermiculite flakes; (2) 5 g of acidified layered vermiculite flakes were ultrasonically dispersed in a mixed solution of 750 mL of ethanol and 250 mL of deionized water, and ammonia water was added to adjust the pH value of the system to 8 to obtain a suspension. 20 mL of tetraethyl silicate was dissolved in 200 mL of anhydrous ethanol and added to the suspension, and ultrasonically dispersed evenly. The mixture was stirred for 18 h to obtain a dispersion. 0.5 g of 3-aminopropyltriethoxysilane was dissolved in a mixed solution of 10 mL of ethanol and 10 mL of acetic acid, and then added to the dispersion and stirred for reaction for 7 h. After the reaction was completed, the composite filler was prepared by centrifugation, washing, and drying.

[0023] Embodiment 2 A method for preparing a modified glass fiber comprises the following steps: A. Take 2.6 g of glycidyl ether and 3.3 g of p-phenylenediamine in a reactor, add 70 mL of toluene solvent, place at 100 ° C and stir for 12 hours, cool to room temperature after the reaction is completed, and remove the solvent by rotary evaporation to prepare an anti-aging component; B. Take 6.5g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 6.9g of octenylsuccinic anhydride in a reactor, add 100mL of tetrahydrofuran solvent, stir and react at 50°C for 7h, and after the reaction is completed, perform rotary evaporation, wash and dry to prepare a flame retardant component; C. Take 5.8g of anti-aging component and 8.7g of flame retardant component in a reactor, add 100mL of N,N-dimethylformamide solvent, place at 75°C and stir for 10h. After the reaction is completed, filter, wash and dry to prepare a functional modifier; D. Take 2g of carboxylated glass fiber and ultrasonically disperse it in 120mL of deionized water, add 2.5g of functional modifier and stir to mix, use 10% sodium carbonate solution to adjust the pH value of the system to 8, then add 1.4g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 2.1g of N-hydroxysuccinimide and stir to react for 5h. After the reaction is completed, filter and dry to prepare modified glass fiber.

[0024] The preparation method of carboxylated glass fiber comprises the following steps: D1. Take 10g of glass fiber, place it in an acetone solution for ultrasonic treatment and soak it for 10 hours. After drying, soak it in a mixed solution of 280mL of concentrated sulfuric acid and 120mL of hydrogen peroxide and stir it for 12 hours to prepare a pretreated glass fiber; D2, immersing the pretreated glass fiber in a 10% 3-aminopropyltriethoxysilane toluene solution and condensing and refluxing at 110° C. for 10 hours, and after the reaction is completed, repeatedly washing with toluene and drying to prepare an amino glass fiber; D3. Take 2g of amino glass fiber and ultrasonically disperse it in 50mL of N,N-dimethylformamide, add 50mL of 0.5mol / L succinic anhydride and stir to mix, place it at 65°C and stir to react for 24h. After the reaction is completed, wash and dry it to prepare carboxylated glass fiber.

[0025] Embodiment 3 A method for preparing a high-strength polypropylene reinforced composite pipe comprises the following steps: S1, taking 100 parts of copolymerized polypropylene, 3 parts of the composite filler prepared in Example 1, 7 parts of the modified glass fiber prepared in Example 2, 3 parts of polymer compatibilizer maleic anhydride grafted polypropylene, 1 part of lubricant polyethylene wax and 0.05 parts of antioxidant 1010 and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Spirally wrap the reinforcing ribs along the profile plastic pipes and bond them to the outer surface of the pipes to prepare a high-strength polypropylene reinforced composite pipe.

[0026] Example 4 A method for preparing a high-strength polypropylene reinforced composite pipe comprises the following steps: S1, taking 100 parts of copolymerized polypropylene, 5 parts of the composite filler prepared in Example 1, 12 parts of the modified glass fiber prepared in Example 2, 5 parts of a polymer compatibilizer ethylene-vinyl acetate copolymer, 2 parts of a lubricant polyethylene wax and 0.5 parts of an antioxidant 168 and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Spirally wrap the reinforcing ribs along the profile plastic pipes and bond them to the outer surface of the pipes to prepare a high-strength polypropylene reinforced composite pipe.

[0027] Example 5 A method for preparing a high-strength polypropylene reinforced composite pipe comprises the following steps: S1, taking 100 parts of copolymerized polypropylene, 8 parts of the composite filler prepared in Example 1, 17 parts of the modified glass fiber prepared in Example 2, 7 parts of polymer compatibilizer maleic anhydride grafted polyethylene, 3 parts of lubricant polyethylene wax and 3 parts of antioxidant 3114 and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Spirally wrap the reinforcing ribs along the profile plastic pipes and bond them to the outer surface of the pipes to prepare a high-strength polypropylene reinforced composite pipe.

[0028] Comparative Example 1 A method for preparing a high-strength polypropylene reinforced composite pipe comprises the following steps: S1, taking 100 parts of copolymerized polypropylene, 5 parts of nano-silicon dioxide, 12 parts of modified glass fiber prepared in Example 2, 5 parts of polymer compatibilizer ethylene-vinyl acetate copolymer, 2 parts of lubricant polyethylene wax and 0.5 parts of antioxidant 168 and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Spirally wrap the reinforcing ribs along the profile plastic pipes and bond them to the outer surface of the pipes to prepare a high-strength polypropylene reinforced composite pipe.

[0029] Comparative Example 2 A method for preparing a high-strength polypropylene reinforced composite pipe comprises the following steps: S1, taking 100 parts of copolymerized polypropylene, 5 parts of the composite filler prepared in Example 1, 12 parts of glass fiber, 5 parts of polymer compatibilizer ethylene-vinyl acetate copolymer, 2 parts of lubricant polyethylene wax and 0.5 parts of antioxidant 168 and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Spirally wrap the reinforcing ribs along the profile plastic pipes and bond them to the outer surface of the pipes to prepare a high-strength polypropylene reinforced composite pipe.

[0030] Performance Testing The high-strength polypropylene reinforced composite pipes prepared in Examples 3-5 and Comparative Examples 1-2 were injection molded into standard dumbbell-shaped specimens with a thickness of 4 mm, and performance tests were performed: a. According to GB / T 1040.2-2022 standard, the tensile properties of the material were tested at a tensile rate of 50 mm / min; the limiting oxygen index of the material was tested according to GB / T 2406.2-2009 to evaluate the flame retardant properties of the sample; the sample was placed in a TGA-103 thermogravimetric analyzer, and under nitrogen protection, the temperature was increased from room temperature to 800°C at a rate of 5°C / min, the initial decomposition temperature of the material was recorded, and the heat resistance of the sample was evaluated. The data results are shown in Table 1.

[0031] Table 1 Test results of various properties of samples

[0032] From the data results in Table 1, it can be seen that the pipes prepared in Examples 3-5 of the present invention have high tensile strength, are not easy to break, and have excellent heat resistance and flame retardant properties. In Comparative Example 1, the composite filler is replaced with nano-silicon dioxide in equal amounts, and the tensile properties and initial thermal decomposition temperature measured are lower than those of Examples 3-5, indicating that the addition of the composite filler can improve the mechanical properties and heat resistance of the pipe. In Comparative Example 2, the glass fiber is not modified, and the tensile properties and limiting oxygen index measured are lower than those of Examples 3-5. The reason is that the anti-aging component and the flame retardant component are not modified on the surface of the glass fiber, resulting in a decrease in its flame retardant property, and the agglomeration of the glass fiber leads to a decrease in the mechanical properties of the pipe.

[0033] b. The samples were placed in an air thermal aging test chamber for high-temperature thermal oxidation aging at 100°C. The aging cycle was divided into four test cycles of 3, 6, 12, and 24 days. Five samples were taken in each cycle. Each sample was tested for oxidation induction time to evaluate the high-temperature aging resistance of the pipe. The data results are shown in Table 2.

[0034] Table 2 Test results of high temperature aging resistance of samples

[0035] From the data in Table 2, it can be seen that the pipes prepared in Examples 3-5 of the present invention have a long oxidation induction time, and after 24 days of thermal oxidation aging, they still maintain a long oxidation induction time, and have excellent high temperature aging resistance. In Comparative Example 2, the glass fiber was not modified, and the oxidation induction time measured was significantly shorter than that of Examples 3-5. The reason is that the anti-aging component was not modified on the surface of the glass fiber, resulting in poor high temperature aging resistance.

[0036] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0037] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A high-strength polypropylene reinforced composite pipe, characterized in that: It comprises a pipe and a profile plastic pipe spirally wound and bonded to the outer surface of the pipe, wherein the interior of the profile plastic pipe is a hollow structure, and two sheets are provided inside the profile plastic pipe, which are fitted with each other, and the two sheets separate the profile plastic pipe into two hollow pipes, and the outer wall of the pipe and the end face of the profile plastic pipe away from the outer wall of the pipe are both provided with embedded steel wires, and reinforcing ribs are equidistantly provided between the profile plastic pipes along the circumferential direction of the pipe; The profile plastic pipe is obtained by melting and extruding the pipe composition through a twin-screw extruder and cooling and shaping; the pipe composition comprises the following raw materials in parts by weight: 100 parts of polypropylene, 3-8 parts of composite filler, 5-20 parts of modified glass fiber, 2-8 parts of polymer compatibilizer, 1-3 parts of lubricant, and 0.05-5 parts of antioxidant; The composite filler is made by attaching nano silicon dioxide particles to the surface of layered vermiculite sheets by using sol-gel method and 3-aminopropyltriethoxysilane; the modified glass fiber is made by modifying the anti-aging component and the flame retardant component on the surface of the carboxylated glass fiber by chemical reaction, wherein the anti-aging component is made by ring-opening reaction of glycidyl ether and p-phenylenediamine, and the flame retardant component is made by addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and octenyl succinic anhydride.

2. The high-strength polypropylene reinforced composite pipe according to claim 1, characterized in that: The polymer compatibilizer is one or more combinations of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polyethylene, acrylic acid grafted polyethylene, silane grafted polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-acrylate copolymer, and ethylene acrylic acid copolymer.

3. The high-strength polypropylene reinforced composite pipe according to claim 1, characterized in that: The lubricant is one of polyethylene wax and oxidized polyethylene wax; the antioxidant is one or more combinations of antioxidant DLTP, antioxidant 168, antioxidant 1010, antioxidant 1076, antioxidant 3114, and antioxidant 1024.

4. The high-strength polypropylene reinforced composite pipe according to claim 1, characterized in that: The preparation method of the composite filler comprises the following steps: (1) taking expanded vermiculite and dispersing it uniformly in a mixed solution of concentrated sulfuric acid and concentrated nitric acid by ultrasonication, placing it under reflux reaction at 110-125°C for 4-6 hours, and washing, drying and grinding it after the reaction is completed to prepare acidified layered vermiculite flakes; (2) Acidified layered vermiculite flakes were ultrasonically dispersed in a mixed solution of ethanol and deionized water, and ammonia water was added to adjust the pH value of the system to 8-9 to obtain a suspension. Tetraethyl silicate was dissolved in anhydrous ethanol and added to the suspension, ultrasonically dispersed evenly, and then stirred for 16-18 hours to obtain a dispersion. 3-aminopropyltriethoxysilane was dissolved in a mixed solution of ethanol and acetic acid, and then added to the dispersion and stirred for reaction for 5-7 hours. After the reaction was completed, the composite filler was prepared by centrifugation, washing, and drying.

5. The high-strength polypropylene reinforced composite pipe according to claim 1, characterized in that: The preparation method of the modified glass fiber comprises the following steps: A. Put glycidyl ether and p-phenylenediamine in a reactor, add toluene solvent, place at 95-105°C and stir to react for 10-12 hours. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and prepare an anti-aging component; B. 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and octenyl succinic anhydride are placed in a reactor, tetrahydrofuran solvent is added, and the mixture is stirred at 45-60° C. for 5-7 hours. After the reaction is completed, the mixture is subjected to rotary evaporation, washing, and drying to prepare a flame retardant component; C. Put the anti-aging component and the flame retardant component into a reactor, add N,N-dimethylformamide solvent, stir and react at 60-85°C for 6-12h, filter, wash and dry after the reaction to obtain a functional modifier; D. Ultrasonic dispersion of carboxylated glass fiber in deionized water, adding functional modifier and stirring to mix, adjusting the pH value of the system to 7-9 with sodium carbonate solution, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide and stirring to react for 4-6 hours, after the reaction is completed, filtering and drying to prepare modified glass fiber.

6. The high-strength polypropylene reinforced composite pipe according to claim 5, characterized in that: The molar ratio of glycidyl ether to p-phenylenediamine in step A is 1:3-3.

4.

7. The high-strength polypropylene reinforced composite pipe according to claim 5, characterized in that: In the step B, the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to octenylsuccinic anhydride is 1:1-1.

2.

8. The high-strength polypropylene reinforced composite pipe according to claim 5, characterized in that: The molar ratio of the anti-aging component to the flame retardant component in step C is 1:2-2.

5.

9. The high-strength polypropylene reinforced composite pipe according to claim 5, characterized in that: The method for preparing the carboxylated glass fiber in step D comprises the following steps: D1. Take the glass fiber and place it in an acetone solution for ultrasonic treatment and immersion to remove the impregnated material on the surface of the glass fiber. After drying, soak it in a mixed solution of concentrated sulfuric acid and hydrogen peroxide and stir for 8 to 12 hours to prepare a pretreated glass fiber; D2, immersing the pretreated glass fiber in a toluene solution of 3-aminopropyltriethoxysilane and condensing and refluxing at 105-115° C. for 8-12 hours, and after the reaction is completed, repeatedly washing with toluene and drying to prepare an amino glass fiber; D3. Take the amino glass fiber and ultrasonically disperse it in N, N-dimethylformamide, add succinic anhydride and stir to mix, place it at 55-70°C and stir to react for 20-24 hours. After the reaction is completed, wash and dry to prepare carboxylated glass fiber.

10. A method for preparing a high-strength polypropylene reinforced composite pipe according to claim 1, characterized in that: The following steps are involved: S1, taking parts by weight of polypropylene, composite filler, modified glass fiber, polymer compatibilizer, lubricant and antioxidant and mixing them evenly to obtain a pipe composition; S2, melt-extrude the pipe composition into a profile plastic pipe mold through a twin-screw extruder, shape it on the outer surface of the pipe, cool it and shape it, and obtain a profile plastic pipe; S3. Embedded steel wires are arranged on the outer wall of the pipe and the end face of the profile plastic pipe away from the outer wall of the pipe, and reinforcing ribs are spirally wound along the profile plastic pipes and bonded to the outer surface of the pipe to prepare a high-strength polypropylene reinforced composite pipe.

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