Thermo-oxidative aging resistant power tube and preparation method thereof

Abstract

The invention relates to a thermo-oxidative aging resistant power tube and a preparation method thereof, and belongs to the technical field of high polymer materials. The thermo-oxidative aging resistant electric power tube comprises the following components in parts by weight: 50-70 parts of polypropylene resin, 10-20 parts of a heat-resistant modifier, 10-20 parts of a modified flame retardant, 1-3 parts of a heat stabilizer, 1-3 parts of a plasticizer, 2-4 parts of a lubricant and 1-3 parts of an antioxidant, the high bond energy of a carbamate group in the heat-resistant modifier and a hydrogen bond synergistically improve the heat stability, an epoxy group of glycidyl methacrylate and polypropylene are subjected to ring opening to form a cross-linked network, and a maleimide group improves the glass transition temperature and the melting point and reduces material aging caused by high temperature; a compact protective layer is formed when silicon-oxygen-boron bonds in the modified flame retardant are combusted, so that the flame-retardant effect is enhanced, and gamma-glycidyl ether oxypropyl trimethoxy silane delays combustion and reduces smoke; the thermo-oxidative aging resistant power tube prepared by the invention not only has a good heat-resistant effect, but also has an excellent flame-retardant effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a heat-oxidation-aging-resistant power pipe and a preparation method thereof. Background Art

[0002] With the rapid development of the national economy and the acceleration of urbanization, the development of electricity in the field of electric power and energy is directly related to the national economy, people's livelihood and national security. The advancement of urban planning and construction has prompted the continuous expansion of the laying scale of power cables. As a cable protection facility, the power pipe is mainly used in the intersection area of communication cables and power lines. It can effectively prevent communication failures and short-circuit accidents caused by disconnection caused by external factors.

[0003] However, in order to maintain a clean and beautiful cityscape, high-voltage power lines are gradually being buried underground. High-voltage cables are prone to heat or instantaneous short-circuit high temperatures due to their high voltage, causing the power pipes to be in a high-temperature environment for a long time, thereby shortening their service life. Traditional polypropylene power pipes are susceptible to molecular structure destruction caused by high temperature and oxygen during long-term outdoor use, resulting in molecular structure damage and accelerated material aging. In addition, polypropylene power pipes are derived from petrochemical materials and are composed of hydrocarbon elements. They are flammable and increase the risk of fire. These problems limit the wider and deeper application of power pipes. Therefore, the research and development of power pipes with excellent heat-oxidation aging resistance has important practical significance and application value. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a heat-oxidation-aging-resistant power pipe and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A heat-oxidation-aging-resistant power pipe and a preparation method thereof, comprising the following raw materials in parts by weight: 50-70 parts of polypropylene resin, 10-20 parts of a heat-resistant modifier, 10-20 parts of a modified flame retardant, 1-3 parts of a heat stabilizer, 1-3 parts of a plasticizer, 2-4 parts of a lubricant, and 1-3 parts of an antioxidant; The heat stabilizer is zinc stearate; The plasticizer is dibutyl phthalate; The lubricant is ethylene bisstearamide; The antioxidant is antioxidant 1076.

[0006] The heat-resistant modifier is prepared by the following method: Step A1: Maleic anhydride, toluene, and N,N-dimethylformamide were mixed uniformly, and p-aminophenol was added. The mixture was stirred at room temperature for 3 hours, filtered, washed, and dried under vacuum at 50°C. p-Toluenesulfonic acid was added, and the mixture was refluxed at 110°C for 12 hours. The mixture was cooled, decompressed, filtered, and dried. m-Chlorophenyl isocyanate and triethylamine were added, and the mixture was reacted at 50°C for 0.5 hours to obtain the compound. Furthermore, the usage ratio of maleic anhydride, toluene, N,N-dimethylformamide, p-aminophenol, p-toluenesulfonic acid, m-chlorophenyl isocyanate, and triethylamine is 0.01-0.02 mol: 20 mL: 20 mL: 0.01-0.02 mol: 3.8 g: 0.01-0.02 mol: 20-40 mL; First, maleic anhydride is reacted with the amino group of p-aminophenol, and then the hydroxyl group of p-aminophenol is reacted with the isocyanate group of m-chlorophenyl isocyanate to prepare the compound; Step A2: uniformly mixing the compound, benzoyl peroxide, and xylene, then adding styrene and glycidyl methacrylate and stirring evenly, reacting at 105° C. for 4 h, distilling under reduced pressure, washing, filtering, and vacuum drying to obtain a heat-resistant modifier; Furthermore, the ratio of the compound, benzoyl peroxide, xylene, styrene, and glycidyl methacrylate is 0.01-0.02 mol: 0.03-0.06 g: 30 mL: 0.01-0.02 mol: 0.01-0.02 mol; Finally, the heat-resistant modifier is prepared by copolymerizing the carbon-carbon double bond of the compound, styrene and glycidyl methacrylate.

[0007] The modified flame retardant is prepared by the following method: Step B1: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and γ-glycidyloxypropyltrimethoxysilane are mixed uniformly at 100-120° C., N,N-dimethylacetamide is added, the temperature is raised to 120-140° C., and the mixture is stirred for 3 h. The mixture is distilled under reduced pressure, washed, and dried in vacuo at 120° C. to obtain an intermediate; Furthermore, the usage ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, γ-glycidyloxypropyltrimethoxysilane, and N,N-dimethylacetamide is 0.01-0.02 mol: 0.01-0.02 mol: 30-50 mL; First, an intermediate is generated by reacting the epoxy group of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with γ-glycidyloxypropyltrimethoxysilane; Step B2: Boric acid and tetrahydrofuran were mixed evenly, stirred for 1 hour, the pH of the system was adjusted to 4-6, and then the intermediate was added. After reacting at 60°C for 12 hours, the mixture was distilled under reduced pressure, washed, and dried in vacuo at 90°C for 10 hours to obtain a modified flame retardant. Furthermore, the ratio of boric acid, tetrahydrofuran, and intermediate is 0.01-0.02 mol: 5-10 mL: 0.01-0.02 mol; Finally, the modified flame retardant is prepared by reacting the hydrolyzed silanol group of the intermediate with the hydroxyl group of boric acid.

[0008] A method for preparing a heat-oxidation-aging-resistant power pipe comprises the following steps: S1. Mix polypropylene resin, heat-resistant modifier, modified flame retardant and heat stabilizer uniformly, and stir for 15-30 minutes to prepare a premixed material; S2. Evenly mix the premixed material, plasticizer, lubricant and antioxidant, stir at 150-160° C. for 10-20 min, transfer to a twin-screw extruder for extrusion, vacuum shape, cool, pull and coil to obtain a heat-resistant oxygen aging power pipe.

[0009] Beneficial effects of the present invention: The heat-resistant oxygen aging electric power pipe of the present invention has good heat resistance and excellent flame retardant effect, thereby extending the service life of the material.

[0010] The heat-resistant modifier prepared by the present invention exhibits performance that surpasses traditional small-molecule heat-resistant agents with its structural advantages of macromolecular polymers. The carbamate group formed in the heat-resistant modifier has a high bond energy, which synergistically improves the thermal stability of the material with the hydrogen bond in the molecular chain. The chemical stability of the carbamate bond inhibits the degradation of polypropylene under thermal oxidative conditions, and the acid and alkali resistance of the ester group of the carbamate bond protects the polypropylene matrix from corrosion. At the same time, the epoxy group of glycidyl methacrylate can undergo a ring-opening reaction with the polypropylene molecular chain to form a cross-linked network, reduce the free radical reaction of the polypropylene molecular chain, delay the thermal oxidation process and limit the movement of the molecular chain, and further improve the thermal stability of the material. In addition, the maleimide group increases the glass transition temperature and melting point of the material by enhancing the intermolecular force, enhances the rigidity and heat resistance of the molecular chain, and reduces the aging of the material caused by high-temperature thermal aging. In addition, the heat-resistant modifier has high compatibility with polypropylene, solving the migration, incompatibility and volatilization problems of traditional heat-resistant modifiers.

[0011] The silicon-oxygen-boron bonds in the modified flame retardant prepared by the present invention form a dense protective layer during combustion, covering the surface of the expanded carbon layer. By inhibiting the escape of combustible gas and the entry of oxygen, the substrate is protected, and the flame retardant effect of the material is significantly enhanced. The high-bond energy BO bond and Si-O bond structure thereof improve the thermal stability of the flame retardant. In addition, γ-glycidyloxypropyltrimethoxysilane can promote the formation of a dense carbonized layer on the surface of polypropylene during combustion, inhibit heat transfer and oxygen diffusion, delay the combustion process and reduce smoke generation. In addition, the phosphorus-nitrogen flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphaphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous carbon layer during combustion, isolates oxygen and heat, and synergistically enhances the flame retardant effect with the phosphorus-oxygen double bond, thereby extending the service life. In addition, the modified flame retardant prepared by the present invention is halogen-free, helps reduce environmental pollution and damage to the ecosystem, is harmless to human health, and achieves sustainable development. DETAILED DESCRIPTION

[0012] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0013] Example 1: A method for preparing a heat-oxidation-aging-resistant power pipe, comprising the following steps: S1. Weigh the raw materials by weight: 50 parts of polypropylene resin, 10 parts of heat-resistant modifier (prepared in this example), 10 parts of modified flame retardant (prepared in this example), 1 part of heat stabilizer, 1 part of plasticizer, 2 parts of lubricant, and 1 part of antioxidant; mix the polypropylene resin, heat-resistant modifier, modified flame retardant, and heat stabilizer uniformly, and stir for 15 minutes to prepare a premixed material; S2. The premixed material, plasticizer, lubricant and antioxidant were mixed evenly, stirred at 150° C. for 10 min, and extruded into a twin-screw extruder, vacuum-shaped, cooled, pulled and coiled to obtain a heat-resistant oxygen aging power pipe; The heat-resistant modifier is prepared by the following method: Step A1: 0.01 mol of maleic anhydride, 20 mL of toluene, and 20 mL of N,N-dimethylformamide were mixed uniformly, and then 0.01 mol of p-aminophenol was added. The mixture was stirred at room temperature for 3 h, filtered, washed, and dried in vacuo at 50°C. 3.8 g of p-toluenesulfonic acid was then added, and the mixture was refluxed at 110°C for 12 h. The mixture was cooled, decompressed, filtered, and dried. 0.01 mol of m-chlorophenyl isocyanate and 20 mL of triethylamine were added, and the mixture was reacted at 50°C for 0.5 h to obtain the compound; Step A2: 0.01 mol of the compound, 0.03 g of benzoyl peroxide, and 30 mL of xylene were mixed evenly, and then 0.01 mol of styrene and 0.01 mol of glycidyl methacrylate were added and stirred evenly. The mixture was reacted at 105° C. for 4 h, and then distilled under reduced pressure, washed, filtered, and dried in vacuo to obtain a heat-resistant modifier. The modified flame retardant is prepared by the following method: Step B1: 0.01 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.01 mol of γ-glycidyloxypropyltrimethoxysilane were mixed at 100°C, and then 30 mL of N,N-dimethylacetamide was added. The mixture was heated to 120°C and stirred for 3 hours. The mixture was distilled under reduced pressure, washed, and dried in vacuo at 120°C to obtain an intermediate. Step B2: 0.01 mol of boric acid and 5 mL of tetrahydrofuran were mixed evenly, stirred for 1 h, the pH of the system was adjusted to 4, and then 0.01 mol of the intermediate was added. After reacting at 60°C for 12 h, the mixture was distilled under reduced pressure, washed, and vacuum dried at 90°C for 10 h to obtain a modified flame retardant.

[0014] Example 2: A method for preparing a heat-oxidation-aging-resistant power pipe, comprising the following steps: S1. Weigh the raw materials by weight: 60 parts of polypropylene resin, 15 parts of heat-resistant modifier (prepared in this example), 15 parts of modified flame retardant (prepared in this example), 2 parts of heat stabilizer, 2 parts of plasticizer, 3 parts of lubricant, and 2 parts of antioxidant; mix the polypropylene resin, heat-resistant modifier, modified flame retardant, and heat stabilizer uniformly, and stir for 22 minutes to prepare a premixed material; S2. The premixed material, plasticizer, lubricant and antioxidant were mixed uniformly, stirred at 155° C. for 15 minutes, and then extruded into a twin-screw extruder, vacuum-shaped, cooled, pulled and coiled to obtain a heat-resistant oxygen aging power pipe; The heat-resistant modifier is prepared by the following method: Step A1: 0.015 mol of maleic anhydride, 20 mL of toluene, and 20 mL of N,N-dimethylformamide were mixed uniformly, and then 0.015 mol of p-aminophenol was added. The mixture was stirred at room temperature for 3 h, filtered, washed, and dried in vacuo at 50°C. 3.8 g of p-toluenesulfonic acid was then added, and the mixture was refluxed at 110°C for 12 h. The mixture was cooled, decompressed, filtered, and dried. 0.015 mol of m-chlorophenyl isocyanate and 30 mL of triethylamine were added, and the mixture was reacted at 50°C for 0.5 h to obtain the compound; Step A2: 0.015 mol of the compound, 0.045 g of benzoyl peroxide, and 30 mL of xylene were mixed evenly, and then 0.015 mol of styrene and 0.015 mol of glycidyl methacrylate were added and stirred evenly. The mixture was reacted at 105° C. for 4 h, and then distilled under reduced pressure, washed, filtered, and dried in vacuo to obtain a heat-resistant modifier. The modified flame retardant is prepared by the following method: Step B1: 0.015 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.015 mol of γ-glycidyloxypropyltrimethoxysilane were mixed at 110°C, and then 40 mL of N,N-dimethylacetamide was added. The mixture was heated to 130°C and stirred for 3 hours. The mixture was distilled under reduced pressure, washed, and dried in vacuo at 120°C to obtain an intermediate. Step B2: 0.015 mol of boric acid and 7.5 mL of tetrahydrofuran were mixed evenly, stirred for 1 hour, the pH of the system was adjusted to 5, and then 0.015 mol of the intermediate was added. After reacting at 60°C for 12 hours, the mixture was distilled under reduced pressure, washed, and vacuum dried at 90°C for 10 hours to obtain a modified flame retardant.

[0015] Example 3: A method for preparing a heat-oxidation-aging-resistant power pipe, comprising the following steps: S1. Weigh the raw materials by weight: 70 parts of polypropylene resin, 20 parts of heat-resistant modifier (prepared in this example), 20 parts of modified flame retardant (prepared in this example), 3 parts of heat stabilizer, 3 parts of plasticizer, 4 parts of lubricant, and 3 parts of antioxidant; mix the polypropylene resin, heat-resistant modifier, modified flame retardant, and heat stabilizer uniformly, and stir for 30 minutes to prepare a premixed material; S2. The premixed material, plasticizer, lubricant and antioxidant were mixed evenly, stirred at 160° C. for 20 min, and then extruded into a twin-screw extruder, vacuum-shaped, cooled, pulled and coiled to obtain a heat-resistant oxygen aging power pipe; The heat-resistant modifier is prepared by the following method: Step A1: 0.02 mol of maleic anhydride, 20 mL of toluene, and 20 mL of N,N-dimethylformamide were mixed uniformly, and then 0.02 mol of p-aminophenol was added. The mixture was stirred at room temperature for 3 h, filtered, washed, and dried in vacuo at 50°C. 3.8 g of p-toluenesulfonic acid was then added, and the mixture was refluxed at 110°C for 12 h. The mixture was cooled, decompressed, filtered, and dried. 0.02 mol of m-chlorophenyl isocyanate and 40 mL of triethylamine were added, and the mixture was reacted at 50°C for 0.5 h to obtain the compound; Step A2: 0.02 mol of the compound, 0.06 g of benzoyl peroxide, and 30 mL of xylene were mixed evenly, and then 0.02 mol of styrene and 0.02 mol of glycidyl methacrylate were added and stirred evenly. The mixture was reacted at 105° C. for 4 h, and then distilled under reduced pressure, washed, filtered, and dried in vacuo to obtain a heat-resistant modifier. The modified flame retardant is prepared by the following method: Step B1: 0.02 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.02 mol of γ-glycidyloxypropyltrimethoxysilane were mixed at 120°C, and then 50 mL of N,N-dimethylacetamide was added. The mixture was heated to 140°C and stirred for 3 hours. The mixture was distilled under reduced pressure, washed, and dried in vacuo at 120°C to obtain an intermediate. Step B2: 0.02 mol of boric acid and 10 mL of tetrahydrofuran were mixed evenly, stirred for 1 h, the pH of the system was adjusted to 6, and then 0.02 mol of the intermediate was added. After reacting at 60° C. for 12 h, the mixture was distilled under reduced pressure, washed, and vacuum dried at 90° C. for 10 h to obtain a modified flame retardant.

[0016] Comparative Example 1: This comparative example is a heat-resistant oxygen aging power pipe. The difference from Example 3 is that an equal amount of wollastonite is used to replace the heat-resistant modifier prepared in Example 3, and the rest are the same.

[0017] Comparative Example 2: This comparative example is a heat-oxidation-aging-resistant power tube. The difference from Example 3 is that an equal amount of magnesium hydroxide is used to replace the modified flame retardant prepared in Example 3, and the rest are the same.

[0018] Performance test: The heat-resistant oxygen aging power pipes prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes, and the heat deformation temperature was tested in accordance with GB / T1634.1-2019 "Standard for Determination of Deformation Temperature of Plastics under Load"; the power pipes cut into standard sizes were placed in an artificial acceleration box at 85°C for artificial accelerated aging for 100 hours, and then cooled to room temperature to measure the retention rate of tensile strength after aging. The larger the value, the higher the heat aging resistance; the oxygen index was tested in accordance with GB / T2406-93 "Plastic Combustion Performance Test Method Gas Index Method"; the test results are shown in Table 1 below: Table 1

[0019] It can be seen from the test data in Table 1 that the heat-resistant oxygen aging power pipe produced by the present invention has good heat resistance. It can also be seen from Table 1 that the heat-resistant oxygen aging power pipe produced by the present invention has good flame retardant effect, which extends the service life of the material.

[0020] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a heat-oxidation-aging-resistant power pipe, characterized in that: The specific steps include: S1. Weigh the raw materials by weight: 50-70 parts of polypropylene resin, 10-20 parts of heat-resistant modifier, 10-20 parts of modified flame retardant, 1-3 parts of heat stabilizer, 1-3 parts of plasticizer, 2-4 parts of lubricant, and 1-3 parts of antioxidant; mix the polypropylene resin, heat-resistant modifier, modified flame retardant, and heat stabilizer uniformly, and stir for 15-30 minutes to prepare a premixed material; S2. The premixed material, plasticizer, lubricant and antioxidant are mixed evenly, stirred at 150-160° C. for 10-20 minutes, and then extruded into a twin-screw extruder, vacuum-shaped, cooled, pulled and coiled to obtain a heat-resistant oxygen aging power pipe; The heat-resistant modifier is prepared by the following method: Step A1: Maleic anhydride, toluene, and N,N-dimethylformamide were mixed uniformly, and p-aminophenol was added. The mixture was stirred at room temperature for 3 hours, filtered, washed, and dried under vacuum at 50°C. p-Toluenesulfonic acid was added, and the mixture was refluxed at 110°C for 12 hours. The mixture was cooled, decompressed, filtered, and dried. m-Chlorophenyl isocyanate and triethylamine were added, and the mixture was reacted at 50°C for 0.5 hours to obtain the compound. Step A2: The compound, benzoyl peroxide and xylene were mixed evenly, and styrene and glycidyl methacrylate were added and stirred evenly. The mixture was reacted at 105° C. for 4 h, and distilled under reduced pressure, washed, filtered, and dried in vacuo to obtain a heat-resistant modifier.

2. The method for preparing a heat-oxidation-aging-resistant power pipe according to claim 1, characterized in that: In step A1, the usage ratio of maleic anhydride, toluene, N,N-dimethylformamide, p-aminophenol, p-toluenesulfonic acid, m-chlorophenyl isocyanate, and triethylamine is 0.01-0.02 mol: 20 mL: 20 mL: 0.01-0.02 mol: 3.8 g: 0.01-0.02 mol: 20-40 mL.

3. The method for preparing a heat-oxidation-aging-resistant electric power pipe according to claim 1, characterized in that: In step A2, the usage ratio of the compound, benzoyl peroxide, xylene, styrene, and glycidyl methacrylate is 0.01-0.02 mol: 0.03-0.06 g: 30 mL: 0.01-0.02 mol: 0.01-0.02 mol.

4. The method for preparing a heat-oxidation-aging-resistant electric power pipe according to claim 1, characterized in that: The modified flame retardant is prepared by the following method: Step B1: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and γ-glycidyloxypropyltrimethoxysilane are mixed uniformly at 100-120° C., N,N-dimethylacetamide is added, the temperature is raised to 120-140° C., and the mixture is stirred for 3 h. The mixture is distilled under reduced pressure, washed, and dried in vacuo at 120° C. to obtain an intermediate; Step B2: Boric acid and tetrahydrofuran were mixed evenly, stirred for 1 hour, the pH of the system was adjusted to 4-6, and then the intermediate was added. After reacting at 60°C for 12 hours, the mixture was distilled under reduced pressure, washed, and vacuum dried at 90°C for 10 hours to obtain a modified flame retardant.

5. The method for preparing a heat-oxidation-aging-resistant electric power pipe according to claim 4, characterized in that: In step B1, the usage ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, γ-glycidyloxypropyltrimethoxysilane, and N,N-dimethylacetamide is 0.01-0.02 mol: 0.01-0.02 mol: 30-50 mL.

6. The method for preparing a heat-oxidation-aging-resistant electric power pipe according to claim 4, characterized in that: In step B2, the usage ratio of boric acid, tetrahydrofuran, and intermediate is 0.01-0.02 mol: 5-10 mL: 0.01-0.02 mol.

7. The method for preparing a heat-oxidation-aging-resistant electric power pipe according to claim 1, characterized in that: The heat stabilizer is zinc stearate, the plasticizer is dibutyl phthalate, the lubricant is ethylene bisstearamide, and the antioxidant is antioxidant 1076.

8. A heat-oxidation-aging-resistant power pipe, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

Images