High-rigidity flame-retardant weather-resistant polypropylene pipe

Abstract

The invention relates to the technical field of polypropylene pipe preparation, in particular to a high-rigidity flame-retardant weather-resistant polypropylene pipe which is prepared through the following preparation steps that S1, modified ammonium polyphosphate is prepared; s2, preparing modified basalt reinforced fibers; s3, mixing the modified ammonium polyphosphate, the modified basalt reinforced fibers, polypropylene, a metal catalyst, an amino monomer and a stabilizer according to a predetermined ratio to obtain a mixture A; s4, feeding the mixture obtained in S3 into a double-screw extruder for melt extrusion; s5, cooling and stretching treatment is conducted on the pipe preliminarily formed in the step S4; s6, the stretched pipe is subjected to ultraviolet irradiation and anti-oxidation treatment; s7, the pipe is subjected to heat treatment; according to the invention, the rigidity, flame retardance and weather resistance of the pipe are effectively improved through an innovative modification method, the problem that the performance of the traditional polypropylene pipe is insufficient in high-temperature, ultraviolet and aging environments is solved, and the polypropylene pipe can be widely applied to the fields of power cables, communication sheaths and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene pipes, and in particular to a high-rigidity flame-retardant and weather-resistant polypropylene pipe. Background Art

[0002] As an important engineering plastic material, polypropylene (PP) pipes are widely used in construction, chemical industry, water supply and other fields due to their low density, good chemical stability and low cost. However, polypropylene pipes have some significant shortcomings in practical applications, mainly manifested in their poor weather resistance, poor thermal stability, easy aging and other problems. Especially when used outdoors, they are exposed to ultraviolet rays, oxidation or high temperature environments for a long time, and are prone to aging, embrittlement, discoloration and other phenomena, which affect the service life and performance of the pipes. In addition, the low rigidity and poor flame retardancy of polypropylene also limit its widespread use in some high-demand applications, resulting in its inability to meet application requirements in certain special environments.

[0003] In the prior art, although there are some methods for modifying polypropylene to improve its weather resistance, flame retardancy and thermal stability, these methods usually have certain limitations; for example, although the modification using conventional additives and reinforcing fibers can improve certain properties, it often fails to achieve a balance in multiple aspects and sometimes leads to an overall decrease in pipe performance. Summary of the invention

[0004] Based on the above purpose, the present invention provides a high-rigidity flame-retardant and weather-resistant polypropylene pipe.

[0005] A high-rigidity flame-retardant and weather-resistant polypropylene pipe comprises polypropylene, modified ammonium polyphosphate, modified basalt reinforcing fiber, a metal catalyst, an amine monomer and a stabilizer; the specific preparation steps of the high-rigidity flame-retardant and weather-resistant polypropylene pipe include: S1: preparing modified ammonium polyphosphate, reacting ammonium polyphosphate with isocyanate in a solvent to obtain modified ammonium polyphosphate; S2: preparing modified basalt reinforced fiber, reacting basalt fiber with vinyl silane in a solvent to obtain modified basalt reinforced fiber; S3: Mixing modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer according to a predetermined ratio to obtain a mixture A; S4: feeding the mixture A obtained in S3 into a twin-screw extruder for melt extrusion to obtain a preliminary form of a polypropylene pipe; S5: Cooling and stretching the tube initially formed in S4; S6: subjecting the stretched pipe to ultraviolet irradiation and anti-oxidation treatment; S7: Heat treat the pipe and ensure that it has a smooth and defect-free appearance to obtain a high-rigidity flame-retardant and weather-resistant polypropylene pipe finished product.

[0006] Optionally, the components of the high-rigidity flame-retardant and weather-resistant polypropylene pipe are as follows in terms of mass percentage: Polypropylene accounts for 73-88%; Modified ammonium polyphosphate accounts for 5-10%; Modified basalt reinforcing fiber accounts for 5-10%; Metal catalysts account for 1-3%; Amine monomers account for 0.5-2%; Stabilizers account for 0.5-2%.

[0007] Optionally, the metal catalyst is selected from a metallocene catalyst or a transition metal catalyst; the amine monomer is selected from vinylamine or cyclohexenylamine; and the stabilizer is selected from diphenylmethane or butylhydroxytoluene.

[0008] Optionally, the S1 specifically includes: S11: adding ammonium polyphosphate and a solvent in a mass ratio of 1:2 to 1:4 into a reaction kettle, wherein the solvent is xylene or toluene; S12: heating the reactor to 80-120° C. and stirring evenly to allow the ammonium polyphosphate to fully dissolve in the solvent; S13: at the temperature of S12, slowly add isocyanate, the amount of isocyanate is 1.2 to 2 times the mass of ammonium polyphosphate; S14: Continue to heat the reaction mixture, the reaction temperature is controlled at 120-150° C., and the reaction time is 2 to 4 hours, until the isocyanate and the ammonium polyphosphate are fully reacted to form modified ammonium polyphosphate.

[0009] Optionally, the S2 specifically includes: S21: adding basalt fiber and solvent into a reaction container at a mass ratio of 1:3 to 1:5, wherein the solvent is an organic solvent selected from methanol or ethanol; S22: heating the reaction container to 60-90° C. and stirring evenly to ensure that the basalt fiber is completely soaked in the solvent; S23: slowly adding vinyl silane at the temperature of S22, wherein the amount of vinyl silane is 0.5 to 2 times the mass of the basalt fiber; S24: Continue heating the reaction mixture, the reaction temperature is controlled at 90-120° C., and the reaction time is 1 to 2 hours; S25: After the reaction is completed, the mixture is cooled to room temperature, and unreacted solvent and impurities are removed by filtration to obtain modified basalt reinforced fiber.

[0010] Optionally, the S3 specifically includes: S31: adding modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer into a mixing container according to a predetermined mass ratio; S32: firstly mix polypropylene and modified ammonium polyphosphate, stir evenly, control the temperature at 80-100°C, and continue stirring for 15-30 minutes; S33: then adding the modified basalt reinforcing fiber and continuing to stir for 20-40 minutes; S34: After S33 is completed, add the metal catalyst, the amino monomer and the stabilizer, and stir evenly for 10-20 minutes to ensure that all components are evenly mixed; S35: Keep the mixture temperature at 100-120°C and continue stirring for 15-30 minutes to ensure that all components are fully mixed to obtain a uniform mixture A.

[0011] Optionally, the S4 specifically includes: S41: feeding the mixture A obtained in S3 into a twin-screw extruder through a conveying device; S42: In a twin-screw extruder, setting a feed temperature of 180-220° C. and adjusting a barrel temperature of 250-280° C.; S43: Mixing and extruding by a screw of a twin-screw extruder, maintaining the screw speed at 150-300 rpm; S43: Extruding the molten polypropylene mixture through a die to form a preliminary form of a polypropylene pipe.

[0012] Optionally, the S5 specifically includes: S51: sending the polypropylene pipe initially formed in S4 to a cooling zone, and initially cooling the pipe by a cooling water bath, wherein the cooling water temperature is controlled at 20-30°C; S52: The cooled pipe enters the stretching machine for stretching, and the stretching ratio is controlled at 2 to 4 times; S53: During the stretching process, the stretching speed is adjusted to 5-15 m / min; S54: After the stretching process, the pipe is naturally cooled to room temperature by air.

[0013] Optionally, the S6 specifically includes: S61: Send the stretched pipe into the ultraviolet irradiation equipment and adjust the ultraviolet irradiation intensity to 100-150mW / cm²; S62: setting the ultraviolet irradiation time to 2 to 4 hours; S63: After the ultraviolet irradiation is completed, the anti-oxidation treatment is immediately carried out, and the antioxidant is evenly coated on the surface of the pipe with a coating thickness of 0.1-0.3mm.

[0014] Optionally, the S7 specifically includes: S71: sending the pipe after the antioxidant treatment to the heat treatment zone, adjusting the heat treatment temperature to 150-180°C, and the treatment time to 30-60 minutes; S72: During the heat treatment process, the moving speed of the pipe is controlled at 3-6m / min to ensure that the pipe is evenly heated; S73: After the heat treatment is completed, the pipe is immediately cooled, and the cooling medium is air or cold water, and cooled to room temperature; S74: Finally, the appearance of the pipe is inspected to ensure that the appearance of the pipe is smooth and free of defects, so as to obtain the final high-rigidity flame-retardant and weather-resistant polypropylene pipe product.

[0015] Beneficial effects of the present invention: The present invention effectively improves the comprehensive performance of polypropylene pipes by adopting innovative modification methods such as modified ammonium polyphosphate, modified basalt reinforcing fibers, metal catalysts and amino monomers; modified ammonium polyphosphate as a flame retardant can significantly improve the flame retardant properties of the pipes, and the introduction of modified basalt reinforcing fibers not only enhances the rigidity and mechanical strength of the pipes, but also improves the durability of the pipes.

[0016] The present invention effectively regulates the polymerization process of polypropylene by introducing a metal catalyst, thereby further improving the thermal stability of the pipe; the use of an amino monomer effectively improves the weather resistance and anti-yellowing performance of the pipe, thereby ensuring that the pipe is not prone to aging and discoloration during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is a schematic diagram of a method for preparing a high-rigidity flame-retardant and weather-resistant polypropylene pipe according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0020] It should be noted that the references to "one embodiment", "embodiment", "exemplary embodiments", "some embodiments" and the like in the specification indicate that the embodiments described may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0021] In general, a term can be understood, at least in part, from its use in context. For example, depending, at least in part, on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending, at least in part, on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0022] Example 1 like Figure 1 As shown, a high-rigidity flame-retardant and weather-resistant polypropylene pipe comprises polypropylene, modified ammonium polyphosphate, modified basalt reinforcing fiber, a metal catalyst, an amine monomer and a stabilizer; the specific preparation steps of the high-rigidity flame-retardant and weather-resistant polypropylene pipe include: S1: preparing modified ammonium polyphosphate, reacting ammonium polyphosphate with isocyanate in a solvent to obtain modified ammonium polyphosphate, which is used to provide flame retardant properties for subsequent polypropylene modification; S2: preparing modified basalt reinforced fiber, reacting basalt fiber with vinyl silane in a solvent to obtain modified basalt reinforced fiber, the modified basalt reinforced fiber has good bonding strength with the polypropylene matrix, ensuring the strength and durability of the pipe; S3: Mixing modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer according to a predetermined ratio to obtain a mixture A; S4: feeding the mixture A obtained in S3 into a twin-screw extruder for melt extrusion to obtain a preliminary form of a polypropylene pipe; S5: Cooling and stretching the tube initially formed in S4; S6: The stretched pipe is subjected to ultraviolet irradiation and anti-oxidation treatment to improve the weather resistance of the pipe; S7: Heat treat the pipe and ensure that it has a smooth and defect-free appearance to obtain a high-rigidity flame-retardant and weather-resistant polypropylene pipe finished product.

[0023] The components of high rigidity flame retardant weather resistant polypropylene pipe are as follows in terms of mass percentage: Polypropylene accounts for 81%; Modified ammonium polyphosphate accounts for 7%; Modified basalt reinforcement fiber accounts for 8%; Metal catalysts account for 2%; Amine monomers account for 1%; Stabilizers account for 1%.

[0024] The metal catalyst is selected from metallocene catalysts; the amine monomer is selected from vinylamine; and the stabilizer is selected from diphenylmethane.

[0025] S1 specifically includes: S11: adding ammonium polyphosphate and a solvent into a reactor in a mass ratio of 1:3, wherein the solvent is xylene; S12: heating the reactor to 100° C. and stirring evenly to allow the ammonium polyphosphate to be fully dissolved in the solvent; S13: At the temperature of S12, slowly add isocyanate, the amount of isocyanate is 1.6 times the mass of ammonium polyphosphate, to ensure complete reaction; S14: Continue to heat the reaction mixture, control the reaction temperature at 130° C., and react for 3 hours until the isocyanate and the ammonium polyphosphate are fully reacted to form modified ammonium polyphosphate.

[0026] S2 specifically includes: S21: adding basalt fiber and solvent into a reaction container in a mass ratio of 1:4, wherein the solvent is an organic solvent selected from methanol; S22: heating the reaction container to 80° C. and stirring evenly to ensure that the basalt fiber is completely soaked in the solvent; S23: At the temperature of S22, slowly add vinyl silane, the amount of vinyl silane is 1 times the mass of basalt fiber, to ensure full reaction; S24: Continue to heat the reaction mixture, the reaction temperature is controlled at 110° C., and the reaction time is 1.5 hours, until the vinyl silane chemically reacts with the surface of the basalt fiber; S25: After the reaction is completed, the mixture is cooled to room temperature, and unreacted solvent and impurities are removed by filtration to obtain modified basalt reinforced fiber.

[0027] S3 specifically includes: S31: adding modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer into a mixing container according to a predetermined mass ratio; S32: firstly, the polypropylene and the modified ammonium polyphosphate are mixed and stirred evenly, the temperature is controlled at 90°C, and the stirring is continued for 20 minutes to fully combine the polypropylene and the modified ammonium polyphosphate; S33: then adding the modified basalt reinforcing fibers and continuing to stir to ensure that the fibers are evenly dispersed in the polypropylene matrix, the mixing time is 30 minutes; S34: After S33 is completed, add the metal catalyst, the amino monomer and the stabilizer, and stir evenly for 15 minutes to ensure that all components are evenly mixed; S35: Keep the mixture temperature at 110°C and continue stirring for 20 minutes to ensure that all components are fully mixed to obtain a uniform mixture A.

[0028] S4 specifically includes: S41: feeding the mixture A obtained in S3 into a twin-screw extruder through a conveying device to ensure that the mixture is evenly distributed in the extruder; S42: In the twin-screw extruder, the feed temperature is set to 200°C and the barrel temperature is adjusted to 260°C to ensure uniform heating and melting of the mixture; S43: Mixing and extruding by a screw of a twin-screw extruder, maintaining the screw speed at 200 rpm to ensure the stability of the molten mixture; S43: Extruding the molten polypropylene mixture through a die to form a preliminary form of a polypropylene pipe.

[0029] S5 specifically includes: S51: sending the polypropylene pipe initially formed in S4 to a cooling zone, and initially cooling the pipe by a cooling water bath, wherein the cooling water temperature is controlled at 25°C; S52: The cooled pipe enters the stretching machine for stretching treatment, and the stretching ratio is controlled at 3 times to ensure that the mechanical properties of the pipe are enhanced; S53: During the stretching process, the stretching speed is adjusted to 10m / min to ensure that the pipe is evenly stressed and obtains the required size; S54: After the stretching process, the pipe is naturally cooled to room temperature by air to ensure the stability of its size and shape.

[0030] S6 specifically includes: S61: Send the stretched pipe into the ultraviolet irradiation equipment and adjust the ultraviolet irradiation intensity to 120mW / cm²; S62: Set the UV irradiation time to 3 hours to ensure that the pipe surface receives sufficient UV irradiation to improve its UV stability; S63: After the ultraviolet irradiation is completed, the anti-oxidation treatment is immediately carried out, and the antioxidant is evenly coated on the surface of the pipe with a coating thickness of 0.2mm.

[0031] S7 specifically includes: S71: Send the anti-oxidation treated pipe to the heat treatment zone, adjust the heat treatment temperature to 170°C, and the treatment time to 45 minutes to ensure that the internal stress of the pipe is released and further improve its thermal stability; S72: During the heat treatment process, the moving speed of the pipe is controlled to 4m / min to ensure that the pipe is evenly heated; S73: After the heat treatment is completed, the pipe is immediately cooled with air as the cooling medium to room temperature to ensure the stability of the pipe size and shape; S74: Finally, the appearance of the pipe is inspected to ensure that the appearance of the pipe is smooth and free of defects, so as to obtain the final high-rigidity flame-retardant and weather-resistant polypropylene pipe product.

[0032] Example 2 Formula: polypropylene 73%; modified ammonium polyphosphate 10%; modified basalt reinforcing fiber 10%; metal catalyst (transition metal catalyst) 3%; amine monomer (cyclohexenylamine) 2%; stabilizer (butylated hydroxytoluene) 2%.

[0033] Preparation steps: S1: Add ammonium polyphosphate and solvent (toluene) into a reactor in a mass ratio of 1:2, then heat to 80°C and stir to ensure that the ammonium polyphosphate is completely dissolved; under the condition of controlling the temperature at 80°C, slowly add isocyanate in an amount of 1.2 times the mass of the ammonium polyphosphate, and continue stirring; the reaction temperature is maintained at 120°C, and the reaction time is 2 hours, until the isocyanate and the ammonium polyphosphate are fully reacted to obtain modified ammonium polyphosphate; S2: Add basalt fiber and organic solvent (ethanol) in a mass ratio of 1:3 into a reaction vessel, heat to 60°C and stir evenly to ensure that the basalt fiber is completely soaked; then slowly add vinyl silane at this temperature in an amount of 0.5 times the mass of the basalt fiber, continue to heat to 90°C and react for 1 hour; after the reaction is completed, cool the mixture to room temperature and filter to obtain modified basalt reinforced fiber; S3: In a mixing container, modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metallocene catalyst, vinylamine and butylated hydroxytoluene are added in a predetermined mass ratio; first, polypropylene and modified ammonium polyphosphate are mixed and stirred evenly, the temperature is controlled at 80°C, and stirring is continued for 15 minutes; then modified basalt reinforcing fiber is added and stirring is continued for 20 minutes; then, metal catalyst, vinylamine and butylated hydroxytoluene are added and stirred for 10 minutes; finally, the temperature of the mixture is maintained at 100°C and stirring is continued for 15 minutes to ensure that all components are fully mixed to obtain a uniform mixture A; S4: feeding the obtained mixture into a twin-screw extruder through a conveying device; setting the feed temperature to 180°C and the barrel temperature to 250°C; mixing and extruding through the screw, maintaining the screw speed at 150rpm to ensure that the mixture is uniform and melted; then, extruding the molten polypropylene mixture through a die to form a preliminary form of a polypropylene pipe; S5: The initially formed pipe in S4 is sent to a cooling water bath for initial cooling, and the cooling water temperature is controlled at 20°C; the cooled pipe enters a stretching machine, the stretching ratio is controlled at 2 times, and the stretching speed is adjusted to 5m / min to ensure uniform stretching of the pipe; the stretched pipe is naturally cooled to room temperature by air to complete this process; S6: The stretched pipe is sent to the ultraviolet irradiation equipment, the ultraviolet irradiation intensity is set to 100mW / cm², and the irradiation time is 2 hours; after ultraviolet irradiation, the anti-oxidation treatment is immediately carried out, and the antioxidant is evenly coated on the surface of the pipe with a coating thickness of 0.1mm to ensure that the pipe has good anti-oxidation performance; S7: The pipes after antioxidant treatment are sent to the heat treatment area, the heat treatment temperature is adjusted to 150°C, and the treatment time is 30 minutes; during the heat treatment process, the moving speed of the pipe is controlled at 3m / min to ensure that the pipe is evenly heated; after the treatment is completed, the pipe is cooled to room temperature by cold water and an appearance inspection is carried out to ensure that the surface of the pipe is smooth and free of defects, so as to obtain the final high-rigidity flame-retardant and weather-resistant polypropylene pipe product.

[0034] Example 3 Formula: polypropylene 88%; modified ammonium polyphosphate 5%; modified basalt reinforcing fiber 5%; metal catalyst (metallocene catalyst) 1%; amine monomer (vinylamine) 0.5%; stabilizer (diphenylmethane) 0.5%.

[0035] Preparation steps: S1: Add ammonium polyphosphate and solvent (xylene) into a reactor at a mass ratio of 1:4, then heat to 120°C and stir to ensure that the ammonium polyphosphate is completely dissolved; under the condition of controlling the temperature at 120°C, slowly add isocyanate in an amount of 2 times the mass of the ammonium polyphosphate, and continue stirring; the reaction temperature is maintained at 150°C, and the reaction time is 4 hours, until the isocyanate and the ammonium polyphosphate are fully reacted to obtain modified ammonium polyphosphate; S2: Add basalt fiber and organic solvent (methanol) into a reaction vessel at a mass ratio of 1:5, heat to 90°C and stir evenly to ensure that the basalt fiber is completely soaked; then slowly add vinyl silane at this temperature in an amount of 0.5 times the mass of the basalt fiber, continue to heat to 120°C and react for 2 hours; after the reaction is completed, cool the mixture to room temperature and filter to obtain modified basalt reinforced fiber; S3: In a mixing container, add modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metallocene catalyst, vinylamine and diphenylmethane according to a predetermined mass ratio; first, mix polypropylene with modified ammonium polyphosphate, stir evenly, control the temperature at 100°C, and continue stirring for 30 minutes; then add modified basalt reinforcing fiber, and continue stirring for 40 minutes; then, add metal catalyst, vinylamine and diphenylmethane, and stir for 20 minutes; finally, keep the mixture temperature at 120°C and continue stirring for 30 minutes to ensure that all components are fully mixed to obtain a uniform mixture A; S4: feeding the obtained mixture into a twin-screw extruder through a conveying device; setting the feed temperature to 220°C and the barrel temperature to 280°C; mixing and extruding through the screw, maintaining the screw speed at 300rpm to ensure that the mixture is uniform and melted; then, extruding the molten polypropylene mixture through a die to form a preliminary form of a polypropylene pipe; S5: The initially formed pipe in S4 is sent to a cooling water bath for initial cooling, and the cooling water temperature is controlled at 30°C; the cooled pipe enters a stretching machine, the stretching ratio is controlled at 4 times, and the stretching speed is adjusted to 15m / min to ensure uniform stretching of the pipe; the stretched pipe is naturally cooled to room temperature by air to complete this process; S6: The stretched pipe is sent to the ultraviolet irradiation equipment, the ultraviolet irradiation intensity is set to 150mW / cm², and the irradiation time is 4 hours; after ultraviolet irradiation, the anti-oxidation treatment is immediately carried out, and the antioxidant is evenly coated on the surface of the pipe with a coating thickness of 0.3mm to ensure that the pipe has good anti-oxidation performance; S7: The pipes after antioxidant treatment are sent to the heat treatment area, the heat treatment temperature is adjusted to 180°C, and the treatment time is 60 minutes; during the heat treatment process, the moving speed of the pipe is controlled at 6m / min to ensure that the pipe is evenly heated; after the treatment is completed, the pipe is cooled to room temperature by air and an appearance inspection is carried out to ensure that the surface of the pipe is smooth and free of defects, so as to obtain the final high-rigidity flame-retardant and weather-resistant polypropylene pipe product.

[0036] Comparative Example 1 Step 1: Mix polypropylene, stabilizer and antioxidant in proportion, specifically 90% polypropylene, 5% stabilizer and 5% antioxidant respectively; during mixing, the temperature is controlled at 100°C and the stirring time is 15 minutes to ensure that all components are evenly dispersed; Step 2: Feed the mixture into a twin-screw extruder, set the feed temperature to 190°C, the barrel temperature to 220°C, and the screw speed to 180rpm, and extrude the molten material through the extruder and pass through the die to form the preliminary form of the pipe; Step 3: The extruded pipe is cooled in a water bath with the cooling water temperature set at 20°C to ensure that the pipe is quickly shaped; after cooling, the pipe is stretched with a stretching ratio of 2 times and cooled to room temperature through natural air to complete the production of the finished pipe.

[0037] Table 1 Performance parameters comparison of polypropylene pipe products

[0038] The test methods used for each performance index in Table 1 are as follows: Tensile strength(MPa) Test method: Tensile test was performed according to ASTM D638-2022 standard test method; Test standard: tensile rate 5mm / min, sample size 50mm×10mm, test temperature 23℃; Elongation(%) Test method: Tensile test was performed according to ASTM D638-2022 standard test method; Test standard: The sample length is 100mm during the test, and the length change before and after elongation is measured; Flexural modulus (MPa) Test method: Three-point bending test according to ASTM D790-2017 standard; Test standard: Test size is 80mm×10mm×3mm, loading rate is 2mm / min; Weather resistance (hours) Test method: UV aging test according to ASTM G154-2016 standard; Test standard: UV-B lamp, UV intensity 1.5W / m², sample exposed at 60℃; Flame retardancy (oxygen index%) Test method: Test oxygen index according to ASTM D2863-2017 standard; Test standard: combustion chamber temperature is 23°C, air flow rate is 5cm / s; UV resistance (ΔE value) Test method: Measure color change (ΔE value) according to ASTM E313-2020 standard; Test standard: Use a spectrophotometer to test the color difference of the samples before and after; Antioxidant property (oxygen absorption value) Test method: Water absorption test according to ASTM D570-2021 standard; Test standard: The sample is immersed in water for 24 hours and the water absorption is measured;

[0039] It can be seen from Table 1 that Example 1 is the best, and Example 1 performs most outstandingly in all performance indicators, especially in terms of tensile strength, elongation, flexural modulus, weather resistance, flame retardancy, etc., and its performance far exceeds that of Comparative Example 1; although the performance of Examples 2 and 3 has declined, they are still better than Comparative Example 1, showing better comprehensive performance; Comparative Example 1 is significantly worse, especially in key indicators such as weather resistance, tensile strength and flame retardancy.

[0040] Table 2 Comparison of other performance parameters of finished products

[0041] The test methods used for each performance indicator in Table 2 are as follows: Thermal stability(°C) Test method: Test heat deformation temperature according to ASTM D746-2020 standard; Test standard: Temperature change of the sample under 1.8MPa loading; Impact strength (kJ / m²) Test method: Notched impact test according to ASTM D256-2018 standard; Test standard: The test sample is 80mm×10mm×4mm, using the cantilever beam method; Surface hardness (ShoreD) Test method: Hardness test according to ASTM D2240-2021 standard; Test standard: Use Shore D hardness tester, apply pressure 1.5N, test for 5 seconds; Water resistance(%) Test method: Water absorption rate is measured according to ASTM D570-2018 standard; Test standard: soak the sample for 24 hours and measure the weight change; Chemical resistance (solvent immersion time, h) Test method: Test the chemical solvent immersion time according to ASTM D543-2020 standard; Test standard: Soak the sample in various chemical solvents and measure the changes in physical properties after immersion; Antibacterial performance (inhibition rate%) Test method: Antibacterial performance was measured according to ASTM E2149-2020; Test standard: Use bacterial culture method to evaluate the antibacterial effect of samples; Wear resistance (friction coefficient) Test method: Friction coefficient test is carried out according to ASTM D1894-2014 standard; Test standard: Friction coefficient measured using the rotating disk method;

[0042] It can be seen from Table 2 that the various properties of Example 1 are at the best level in all comparison items, especially in thermal stability, impact strength, surface hardness and chemical resistance. The performance of Example 2 and Example 3 is second, although relatively good, but compared with Example 1, there is still a certain gap; Comparative Example 1 performs poorly in all indicators, especially in thermal stability, impact strength and water resistance, showing low comprehensive performance; Overall, Example 1 performs well in all performance indicators and is the best solution, far exceeding Example 2, Example 3 and Comparative Example 1, and has better comprehensive performance.

[0043] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-rigidity flame-retardant and weather-resistant polypropylene pipe, characterized in that: The invention comprises polypropylene, modified ammonium polyphosphate, modified basalt reinforced fiber, metal catalyst, amino monomer and stabilizer; the specific preparation steps of the high-rigidity flame-retardant and weather-resistant polypropylene pipe include: S1: preparing modified ammonium polyphosphate, reacting ammonium polyphosphate with isocyanate in a solvent to obtain modified ammonium polyphosphate; S2: preparing modified basalt reinforced fiber, reacting basalt fiber with vinyl silane in a solvent to obtain modified basalt reinforced fiber; S3: Mixing modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer according to a predetermined ratio to obtain a mixture A; S4: feeding the mixture A obtained in S3 into a twin-screw extruder for melt extrusion to obtain a preliminary form of a polypropylene pipe; S5: Cooling and stretching the tube initially formed in S4; S6: subjecting the stretched pipe to ultraviolet irradiation and anti-oxidation treatment; S7: Heat treat the pipe and ensure that it has a smooth and defect-free appearance to obtain a high-rigidity flame-retardant and weather-resistant polypropylene pipe finished product.

2. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The components of high rigidity flame retardant weather resistant polypropylene pipe are as follows in terms of mass percentage: Polypropylene accounts for 73-88%; Modified ammonium polyphosphate accounts for 5-10%; Modified basalt reinforcing fiber accounts for 5-10%; Metal catalysts account for 1-3%; Amine monomers account for 0.5-2%; Stabilizers account for 0.5-2%.

3. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The metal catalyst is selected from metallocene catalysts or transition metal catalysts; the amine monomer is selected from vinylamine or cyclohexenylamine; and the stabilizer is selected from diphenylmethane or butylhydroxytoluene.

4. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S1 specifically includes: S11: adding ammonium polyphosphate and a solvent in a mass ratio of 1:2 to 1:4 into a reaction kettle, wherein the solvent is xylene or toluene; S12: heating the reactor to 80-120° C. and stirring evenly to allow the ammonium polyphosphate to fully dissolve in the solvent; S13: at the temperature of S12, slowly add isocyanate, the amount of isocyanate is 1.2 to 2 times the mass of ammonium polyphosphate; S14: Continue to heat the reaction mixture, the reaction temperature is controlled at 120-150° C., and the reaction time is 2 to 4 hours, until the isocyanate and the ammonium polyphosphate are fully reacted to form modified ammonium polyphosphate.

5. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S2 specifically includes: S21: adding basalt fiber and solvent into a reaction container at a mass ratio of 1:3 to 1:5, wherein the solvent is an organic solvent selected from methanol or ethanol; S22: heating the reaction container to 60-90° C. and stirring evenly to ensure that the basalt fiber is completely soaked in the solvent; S23: slowly adding vinyl silane at the temperature of S22, wherein the amount of vinyl silane is 0.5 to 2 times the mass of the basalt fiber; S24: Continue heating the reaction mixture, the reaction temperature is controlled at 90-120° C., and the reaction time is 1 to 2 hours; S25: After the reaction is completed, the mixture is cooled to room temperature, and unreacted solvent and impurities are removed by filtration to obtain modified basalt reinforced fiber.

6. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S3 specifically includes: S31: adding modified ammonium polyphosphate, modified basalt reinforcing fiber, polypropylene, metal catalyst, amine monomer and stabilizer into a mixing container according to a predetermined mass ratio; S32: firstly mix polypropylene and modified ammonium polyphosphate, stir evenly, control the temperature at 80-100°C, and continue stirring for 15-30 minutes; S33: then adding the modified basalt reinforcing fiber and continuing to stir for 20-40 minutes; S34: After S33 is completed, add the metal catalyst, the amino monomer and the stabilizer, and stir evenly for 10-20 minutes to ensure that all components are evenly mixed; S35: Keep the mixture temperature at 100-120°C and continue stirring for 15-30 minutes to ensure that all components are fully mixed to obtain a uniform mixture A.

7. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S4 specifically includes: S41: feeding the mixture A obtained in S3 into a twin-screw extruder through a conveying device; S42: In a twin-screw extruder, setting a feed temperature of 180-220° C. and adjusting a barrel temperature of 250-280° C.; S43: Mixing and extruding by a screw of a twin-screw extruder, maintaining the screw speed at 150-300 rpm; S43: Extruding the molten polypropylene mixture through a die to form a preliminary form of a polypropylene pipe.

8. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S5 specifically includes: S51: sending the polypropylene pipe initially formed in S4 to a cooling zone, and initially cooling the pipe by a cooling water bath, wherein the cooling water temperature is controlled at 20-30°C; S52: The cooled pipe enters the stretching machine for stretching, and the stretching ratio is controlled at 2 to 4 times; S53: During the stretching process, the stretching speed is adjusted to 5-15 m / min; S54: After the stretching process, the pipe is naturally cooled to room temperature by air.

9. The high-rigidity flame-retardant and weather-resistant polypropylene pipe according to claim 1, characterized in that: The S6 specifically includes: S61: Send the stretched pipe into the ultraviolet irradiation equipment and adjust the ultraviolet irradiation intensity to 100-150mW / cm²; S62: setting the ultraviolet irradiation time to 2 to 4 hours; S63: After the ultraviolet irradiation is completed, the anti-oxidation treatment is immediately carried out, and the antioxidant is evenly coated on the surface of the pipe with a coating thickness of 0.1-0.3mm.

10. The high rigidity flame retardant weather resistant polypropylene pipe according to claim 1, characterized in that: The S7 specifically includes: S71: sending the pipe after the antioxidant treatment to the heat treatment zone, adjusting the heat treatment temperature to 150-180°C, and the treatment time to 30-60 minutes; S72: During the heat treatment process, the moving speed of the pipe is controlled at 3-6m / min to ensure that the pipe is evenly heated; S73: After the heat treatment is completed, the pipe is immediately cooled, and the cooling medium is air or cold water, and cooled to room temperature; S74: Finally, the appearance of the pipe is inspected to ensure that the appearance of the pipe is smooth and free of defects, so as to obtain the final high-rigidity flame-retardant and weather-resistant polypropylene pipe product.

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