阅读说明：本技术 一种具有耐热性能的mpp电力管制备方法 (Preparation method of MPP (modified Polypropylene) power pipe with heat resistance ) 是由 陈吉林 詹一浪 陈志松 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种具有耐热性能的MPP电力管制备方法,涉及电力管领域,包括电力管耐热层、电力管阻燃层和应力层,将2,6-二叔丁基苯酚加入到三口烧瓶中,将多聚甲醛和催化剂滴加入三口瓶中,得到中间体A,将双酚B和无水碳酸钾加入到三口瓶中,加入亚磷酸三乙酯,得到中间体B,将中间体A和催化剂加入到三口瓶中,加入中间体B,得到该抗氧化剂,解决了现有的MPP电力管易发生氧化变脆和不具备阻燃性能的问题；在高温时分解成N-(2)、NO,NO-(2)等不燃气体,可以稀释空气中的氧气和聚合物受热分解产生的可燃物的浓度,且分解产生的氮的氧化物能捕捉自由基,抑制高聚物的链锁反应,从而达到了阻燃的目的。(The invention discloses a preparation method of an MPP (modified Polypropylene) power pipe with heat resistance, which relates to the field of power pipes and comprises a heat-resistant layer of the power pipe, a flame-retardant layer of the power pipe and a stress layer, wherein 2, 6-di-tert-butylphenol is added into a three-neck flask, paraformaldehyde and a catalyst are dropwise added into the three-neck flask to obtain an intermediate A, bisphenol B and anhydrous potassium carbonate are added into the three-neck flask, triethyl phosphite is added to obtain an intermediate B, the intermediate A and the catalyst are added into the three-neck flask, and the intermediate B is added to obtain an antioxidant, so that the problems that the conventional MPP power pipe is easy to oxidize and become brittle and does not have flame resistance are solved; decomposition to N at high temperature 2 、NO，NO 2 The non-combustible gas can dilute the oxygen in the air and the concentration of combustible substances generated by the thermal decomposition of the polymer, and the nitrogen oxide generated by the decomposition can capture free radicals and inhibit the chain reaction of the high polymer, thereby achieving the purpose of flame retardance.)

1. The preparation method of the MPP power pipe with the heat resistance comprises a power pipe heat-resistant layer (1), a power pipe flame-retardant layer (2) and a stress layer (3), and is characterized in that the stress layer (3) is arranged on the inner layer of the power pipe heat-resistant layer (1), the power pipe flame-retardant layer (2) is arranged on the inner layer of the stress layer (3), and the preparation method of the MPP power pipe with the heat resistance comprises the following processes:

s1: respectively weighing 60-70 parts by weight of polypropylene, 10-30 parts by weight of glass fiber, 2-4 parts by weight of silane coupling agent, 1-5 parts by weight of stearic acid, 1-3 parts by weight of paraffin and 1-2 parts by weight of antioxidant, and uniformly mixing to obtain a heat-resistant layer blend material of the power pipe;

s2: preparing a flame-retardant layer material of the power tube;

s3: respectively adding the heat-resistant layer blend of the power tube and the flame-retardant layer material of the power tube prepared in the S1 and the S2 into different bins, drying and preheating, and extruding by a single-screw extruder;

s4: extruding a heat-resistant layer (1) and a flame-retardant layer (2) of the power tube by a single-screw extruder in a double-layer co-extrusion mode, and heating, melting and plasticizing materials by a screw of the extruder and conveying the materials to a mouth mold of a machine head;

s5: adding a mixture of 1: 3, forming a stress layer (2) between the heat-resistant layer (1) of the power pipe and the flame-retardant layer (2) of the power pipe in a co-extrusion mode through an intermediate stress layer (3) formed by mixing the glass fiber and the polyethylene.

2. The method as set forth in claim 1, wherein the antioxidant is prepared in step S1 by the steps of:

s21: adding 2, 6-di-tert-butylphenol into a three-neck flask provided with an electric stirrer, a nitrogen guide pipe and a thermometer, introducing nitrogen for purging, controlling the reaction temperature by using water bath, filling paraformaldehyde and a catalyst into a conical flask, placing the conical flask on a magnetic stirrer, stirring, controlling the temperature to be 50-60 ℃, pouring into a dropping funnel after the paraformaldehyde is completely depolymerized, dropping into the three-neck flask, controlling the dropping speed to be 1-2 drops/s, reacting for 5-6h, closing the nitrogen, carrying out reduced pressure distillation after full oscillation, recrystallizing, heating by using a heating jacket until the paraformaldehyde is completely dissolved, cooling, crystallizing for 4-8h, and carrying out reduced pressure suction filtration to obtain an intermediate A;

s22: adding bisphenol B and anhydrous potassium carbonate into a three-mouth bottle, adding a stirrer, installing a thermometer, putting the three-mouth bottle into an oil bath kettle with magnetic stirring, adding triethyl phosphite, connecting a condensing device, starting the magnetic stirring, heating to 120-130 ℃, starting the reaction, reacting for 3-4h, stopping heating, and after the temperature is reduced, carrying out reduced pressure distillation to obtain an intermediate B;

s23: adding the intermediate A and a catalyst into a three-neck flask, adding a xylene solvent and a stirrer, putting the three-neck flask into an oil bath kettle with magnetic stirring, installing a thermometer and a constant-pressure funnel, connecting a condensing device, starting the magnetic stirring, heating to 120 ℃ and 130 ℃, adding the intermediate B, reacting for 3-4h, carrying out reduced pressure distillation, recrystallization and filtration to obtain the antioxidant.

3. The method as set forth in claim 2, wherein said catalyst in step S21 is potassium tert-butoxide, and the ratio of 2, 6-di-tert-butylphenol to catalyst is 4.0 g: 0.08g, and the molar ratio of the 2, 6-di-tert-butylphenol to the paraformaldehyde is 1: 2.5.

4. The method as claimed in claim 2, wherein the ratio of bisphenol B to anhydrous potassium carbonate in step S22 is 1g:0.6g, and the molar ratio of bisphenol B to triethyl phosphite is 1: 2.05.

5. The method as set forth in claim 2, wherein said catalyst is organotin in step S23, and the ratio of said intermediate B to said catalyst is 0.05 g: 0.8g, the molar ratio of the intermediate A to the intermediate B is 4.1: 1.

6. The method as set forth in claim 1, wherein the step of preparing the flame retardant layer material of the power tube in step S2 is as follows:

s61: adding pyromellitic dianhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, heating to 120-130 ℃, electromagnetically stirring for 15-20h, pouring the system into distilled water containing concentrated hydrochloric acid, filtering, and washing with distilled water to obtain an intermediate C;

s62: charging intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂Heating to 80-90 ℃ under stirring, reacting for 8-10h, and performing rotary evaporation to obtain an intermediate D;

s63: adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, dropwise adding the intermediate D into the three-necked bottle under stirring, controlling the dropwise adding speed to be 1-2 drops/s, heating to 30-40 ℃, reacting for 24-26h, pouring into distilled water containing concentrated hydrochloric acid, and placing into a drying box at 60-70 ℃ for vacuum drying for 10-20h to obtain the flame-retardant layer material of the power tube.

7. The method as claimed in claim 6, wherein the ratio of pyromellitic anhydride, L-phenylalanine, N-dimethylformamide, pyridine, concentrated hydrochloric acid and distilled water in S61 is 3.30 g: 5.00 g: 20mL of: 2mL of: 5mL of: 100 mL.

8. The method as claimed in claim 6, wherein the intermediate C and SOCl are mixed in step S62₂The dosage ratio of the components is 8.02 g: 15 mL.

9. The method as claimed in claim 6, wherein the ratio of 1, 4-butynediol, triethylamine, N-dimethylacetamide, intermediate D, concentrated hydrochloric acid to distilled water in step S63 is 10.00 g: 3mL of: 20mL of: 8.35 g: 25mL of: 500 mL.

Technical Field

The invention relates to the field of power pipes, in particular to a preparation method of an MPP power pipe with heat resistance.

Background

Along with the development of urban construction, the popularization and application of the trenchless technology are advanced, trenchless construction is deeply carried out in the laying and repairing of underground pipelines such as natural gas, water supply, water discharge, sewage, electric power and information, all aerial spider nets are expected to be buried in the ground in the coming years, an underground buried cable is adopted for transmitting electric power, a modified polypropylene (MPP) plastic jacking pipe for trenchless is used as a plastic sheath pipe for protecting cables in a large amount in engineering, compared with a common HDPE pipe, an MPP pipe is superior in performance, a hot-melt welding joint is good in flexibility, high in welding joint strength and good in temperature resistance, can be used as a dragging pipe with super-length and high traction force, and has excellent stratum settlement resistance and earthquake resistance.

The MPP power tube is comprehensively popularized along with the expansion of application, the development of the MPP power tube has very wide prospect in the good situation of the requirement of a 21 st century plastic tube, the performance requirement of the MPP power tube is higher and higher, the existing MPP power tube is easy to oxidize and become brittle, the service life of a pipeline is shortened, and the MPP power tube does not have flame retardant property.

Therefore, the method for preparing the MPP power pipe with the heat-resistant performance is provided.

Disclosure of Invention

In order to overcome the technical problems, the invention aims to provide a preparation method of an MPP power pipe with heat resistance, which comprises the following steps:

(1) adding 2, 6-di-tert-butylphenol into a three-neck flask, filling paraformaldehyde and a catalyst into a conical flask, pouring the conical flask into a dropping funnel, dropping the conical flask into the dropping funnel to obtain an intermediate A, adding bisphenol B and anhydrous potassium carbonate into the three-neck flask, adding triethyl phosphite to obtain an intermediate B, adding the intermediate A and the catalyst into the three-neck flask, and adding the intermediate B to obtain an antioxidant, wherein the problem that the service life of a pipeline is shortened because the conventional MPP power pipe is easily oxidized and embrittled is solved by adding the antioxidant;

(2) adding pyromellitic anhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked flask to obtain an intermediate C, and adding the intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂And adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle, and dropwise adding the intermediate D into the three-necked bottle to obtain the flame-retardant layer material of the power tube.

The purpose of the invention can be realized by the following technical scheme:

the preparation method of the MPP electric power pipe with the heat resistance comprises an electric power pipe heat-resistant layer, an electric power pipe flame-retardant layer and a stress layer, wherein the stress layer is arranged on the inner layer of the electric power pipe heat-resistant layer, the electric power pipe flame-retardant layer is arranged on the inner layer of the stress layer, and the preparation method of the MPP electric power pipe with the heat resistance comprises the following processes:

s1: respectively weighing 60-70 parts by weight of polypropylene, 10-30 parts by weight of glass fiber, 2-4 parts by weight of silane coupling agent, 1-5 parts by weight of stearic acid, 1-3 parts by weight of paraffin and 1-2 parts by weight of antioxidant, and uniformly mixing to obtain a heat-resistant layer blend material of the power pipe;

s2: preparing a flame-retardant layer material of the power tube;

s3: respectively adding the heat-resistant layer blend of the power tube and the flame-retardant layer material of the power tube prepared in the S1 and the S2 into different bins, drying and preheating, and extruding by a single-screw extruder;

s4: extruding a heat-resistant layer and a flame-retardant layer of the power tube by a single-screw extruder in a double-layer co-extrusion mode, and heating, melting and plasticizing materials by a screw of the extruder and conveying the materials to a head neck mold;

s5: adding a mixture of 1: 3, forming a stress layer between the heat-resistant layer of the power pipe and the flame-retardant layer of the power pipe in a co-extrusion mode.

As a further scheme of the invention: the preparation steps of the antioxidant in the step S1 are as follows:

s21: adding 2, 6-di-tert-butylphenol into a three-neck flask provided with an electric stirrer, a nitrogen guide pipe and a thermometer, then introducing nitrogen for purging, removing oxygen in the reactor, controlling the reaction temperature by using a water bath, filling paraformaldehyde and a catalyst into a conical flask, placing the conical flask on a magnetic stirrer, stirring, controlling the temperature to be 50-60 ℃, pouring the mixture into a dropping funnel after the paraformaldehyde is completely depolymerized, dropping the mixture into the three-neck flask, controlling the dropping speed to be 1-2 drops/s, reacting for 5-6h, closing nitrogen, fully oscillating, carrying out reduced pressure distillation, recrystallizing, heating by using a heating jacket until the mixture is completely dissolved, cooling, crystallizing for 4-8h, and carrying out reduced pressure suction filtration to obtain an intermediate A;

s22: adding bisphenol B and anhydrous potassium carbonate into a three-mouth bottle, adding a stirrer, installing a thermometer, putting the three-mouth bottle into an oil bath kettle with magnetic stirring, adding triethyl phosphite, connecting a condensing device, starting the magnetic stirring, heating to 120-130 ℃, starting the reaction, reacting for 3-4h, stopping heating, and after the temperature is reduced, carrying out reduced pressure distillation to obtain an intermediate B;

s23: adding the intermediate A and a catalyst into a three-neck flask, adding a xylene solvent and a stirrer, putting the three-neck flask into an oil bath kettle with magnetic stirring, installing a thermometer and a constant-pressure funnel, connecting a condensing device, starting the magnetic stirring, heating to 120 ℃ and 130 ℃, adding the intermediate B, reacting for 3-4h, carrying out reduced pressure distillation, recrystallization and filtration to obtain the antioxidant.

As a further scheme of the invention: in the step S21, the catalyst is potassium tert-butoxide, and the dosage ratio of the 2, 6-di-tert-butylphenol to the catalyst is 4.0 g: 0.08g, and the molar ratio of the 2, 6-di-tert-butylphenol to the paraformaldehyde is 1: 2.5.

As a further scheme of the invention: in the step S22, the dosage ratio of the bisphenol B to the anhydrous potassium carbonate is 1g:0.6g, and the molar ratio of the bisphenol B to the triethyl phosphite is 1: 2.05.

As a further scheme of the invention: in the step S23, the catalyst is organic tin, and the dosage ratio of the intermediate B to the catalyst is 0.05 g: 0.8g, the molar ratio of the intermediate A to the intermediate B is 4.1: 1.

As a further scheme of the invention: the preparation steps of the electric power tube flame-retardant layer material in the step S2 are as follows:

s61: adding pyromellitic dianhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, heating to 120-130 ℃, electromagnetically stirring for 15-20h, pouring the system into distilled water containing concentrated hydrochloric acid, filtering, and washing with distilled water to obtain an intermediate C;

s62: charging intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂Heating to 80-90 ℃ under stirring, reacting for 8-10h, and performing rotary evaporation to obtain an intermediate D;

s63: adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, dropwise adding the intermediate D into the three-necked bottle under stirring, controlling the dropwise adding speed to be 1-2 drops/s, heating to 30-40 ℃, reacting for 24-26h, pouring into distilled water containing concentrated hydrochloric acid, and placing into a drying box at 60-70 ℃ for vacuum drying for 10-20h to obtain the flame-retardant layer material of the power tube.

As a further scheme of the invention: in the step S61, the ratio of the amounts of pyromellitic anhydride, L-phenylalanine, N-dimethylformamide, pyridine, concentrated hydrochloric acid and distilled water was 3.30 g: 5.00 g: 20mL of: 2mL of: 5mL of: 100 mL.

As a further scheme of the invention: intermediate C and SOCl in step S62₂The dosage ratio of the components is 8.02 g: 15 mL.

As a further scheme of the invention: in the step S63, the dosage ratio of 1, 4-butynediol, triethylamine, N-dimethylacetamide, the intermediate D, concentrated hydrochloric acid to distilled water is 10.00 g: 3mL of: 20mL of: 8.35 g: 25mL of: 500 mL.

The invention has the beneficial effects that:

(1) the invention adds 2, 6-di-tert-butylphenol into a three-neck flask, puts paraformaldehyde and catalyst into a conical flask, pours into a dropping funnel, drops into the three-neck flask to obtain an intermediate A, adds bisphenol B and anhydrous potassium carbonate into the three-neck flask, adds triethyl phosphite to obtain an intermediate B, adds the intermediate A and catalyst into the three-neck flask, adds the intermediate B to obtain the antioxidant, the antioxidant is hindered phenol antioxidant, the two sides of the hydroxyl of the benzene ring have substituent groups, because the hydroxyl is steric hindrance, H atom is easy to fall off from the molecule, combines with peroxy radical (RO 0-), alkyl oxygen radical (RO-) or hydroxyl radical (-OH) to make it lose activity, thereby terminating the chain reaction of thermal oxidation aging, adding the antioxidant can obviously improve the heat resistance of the material, the material is not easy to be thermally oxidized, thereby achieving the purposes of oxidation resistance and heat resistance;

(2) adding pyromellitic anhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked flask to obtain intermediate C, adding stirring bar, refluxing, and coolingAdding intermediate C and SOCl into a three-necked flask of a coagulation tube₂Adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle, and dropwise adding the intermediate D into the three-necked bottle to obtain the flame-retardant layer material of the power tube, wherein the flame-retardant mechanism of the flame-retardant layer material of the power tube is carried out according to a gas-phase flame-retardant mechanism, and the flame-retardant layer material is decomposed into N at high temperature₂NO and NO₂The non-combustible gas can dilute the concentration of oxygen in the air and combustible substances generated by the thermal decomposition of the polymer, absorb heat in the decomposition process, reduce the surface temperature of the base material, capture free radicals by nitrogen oxides generated by the decomposition, inhibit the chain reaction of the high polymer, and resist high temperature, so that the flame-retardant purpose is achieved.

Drawings

The invention is further described below with reference to the accompanying drawings;

FIG. 1 is a schematic diagram of an overall structure of an MPP power tube with heat resistance performance according to the present invention;

FIG. 2 is a side view of an MPP power tube having thermal resistance properties in accordance with the present invention;

FIG. 3 is a chemical reaction formula of step S21 in the present invention;

FIG. 4 is a chemical reaction formula of step S22 in the present invention;

FIG. 5 is a chemical reaction formula of step S23 in the present invention;

FIG. 6 shows the chemical reaction formula of step S61 in the present invention;

FIG. 7 shows the chemical reaction formula of step S62 in the present invention;

FIG. 8 shows the chemical reaction formula of step S63 in the present invention.

In the figure: 1. a heat-resistant layer of the power pipe; 2. a power tube flame retardant layer; 3. a stress layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to the figures 1-3, the preparation method of the MPP power pipe with the heat resistance comprises a power pipe heat-resistant layer 1, a power pipe flame-retardant layer 2 and a stress layer 3, wherein the stress layer 3 is arranged on the inner layer of the power pipe heat-resistant layer 1, and the power pipe flame-retardant layer 2 is arranged on the inner layer of the stress layer 3;

example 1:

the embodiment is an MPP power tube with heat resistance, and the preparation method of the MPP power tube with heat resistance comprises the following steps:

s1: respectively weighing 60 parts by weight of polypropylene, 10 parts by weight of glass fiber, 4 parts by weight of silane coupling agent, 5 parts by weight of stearic acid, 3 parts by weight of paraffin and 2 parts by weight of antioxidant, and uniformly mixing to obtain a heat-resistant layer mixture of the power pipe;

s2: preparing a flame-retardant layer material of the power tube;

s3: respectively adding the heat-resistant layer blend of the power tube and the flame-retardant layer material of the power tube prepared in the S1 and the S2 into different bins, drying and preheating, and extruding by a single-screw extruder;

s4: extruding a heat-resistant layer 1 and a flame-retardant layer 2 of the power tube by a single-screw extruder in a double-layer co-extrusion mode, and heating, melting and plasticizing materials by an extruder screw to be conveyed to a head neck mold;

s5: adding a mixture of 1: 3, forming a stress layer 3 between the heat-resistant layer 1 of the power pipe and the flame-retardant layer 2 of the power pipe in a co-extrusion mode, wherein the stress layer 3 is formed by mixing glass fibers and polyethylene;

the antioxidant in step S1 is prepared as follows:

s21: adding 2, 6-di-tert-butylphenol into a three-neck flask provided with an electric stirrer, a nitrogen guide pipe and a thermometer, introducing nitrogen for purging, controlling the reaction temperature by using water bath, filling paraformaldehyde and a catalyst into a conical flask, placing the conical flask on a magnetic stirrer, stirring, controlling the temperature to be 50 ℃, pouring into a dropping funnel after the paraformaldehyde is completely depolymerized, dropping into the three-neck flask, controlling the dropping speed to be 1 drop/s, reacting for 5 hours, closing nitrogen, fully shaking, performing reduced pressure distillation, recrystallizing, heating by using a heating sleeve until the nitrogen is completely dissolved, cooling, crystallizing for 4 hours, and performing reduced pressure suction filtration to obtain an intermediate A;

s22: adding bisphenol B and anhydrous potassium carbonate into a three-neck flask, adding a stirrer, installing a thermometer, putting the three-neck flask into an oil bath kettle with magnetic stirring, adding triethyl phosphite, connecting a condensing device, starting the magnetic stirring, heating to 120 ℃, starting the reaction, reacting for 3 hours, stopping heating, and after the temperature is reduced, carrying out reduced pressure distillation to obtain an intermediate B;

s23: adding the intermediate A and a catalyst into a three-necked bottle, adding a xylene solvent and a stirrer, putting the three-necked bottle into an oil bath kettle with magnetic stirring, installing a thermometer and a constant-pressure funnel, connecting a condensing device, starting magnetic stirring, heating to 120 ℃, adding the intermediate B, reacting for 3 hours, then carrying out reduced pressure distillation, recrystallization and filtration to obtain the antioxidant;

the preparation steps of the electric power tube flame-retardant layer material in the step S2 are as follows:

s61: adding pyromellitic dianhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked flask provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, heating to 120 ℃, electromagnetically stirring for 15h, pouring the system into distilled water containing concentrated hydrochloric acid, filtering, and washing with distilled water to obtain an intermediate C;

s62: charging intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂Heating to 80 ℃ under stirring, reacting for 8h, and performing rotary evaporation to obtain an intermediate D;

s63: adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, dropwise adding the intermediate D into the three-necked bottle under stirring, controlling the dropwise adding speed to be 1 drop/s, heating to 30 ℃, reacting for 24 hours, pouring into distilled water containing concentrated hydrochloric acid, and placing the distilled water into a drying box at 60 ℃ for vacuum drying for 10 hours to obtain the flame-retardant layer material of the power tube.

Example 2:

the embodiment is an MPP power tube with heat resistance, and the preparation method of the MPP power tube with heat resistance comprises the following steps:

s1: respectively weighing 60 parts by weight of polypropylene, 10 parts by weight of glass fiber, 2 parts by weight of silane coupling agent, 1 part by weight of stearic acid, 1 part by weight of paraffin and 1 part by weight of antioxidant, and uniformly mixing to obtain a heat-resistant layer mixture of the power pipe;

s2: preparing a flame-retardant layer material of the power tube;

s3: respectively adding the heat-resistant layer blend of the power tube and the flame-retardant layer material of the power tube prepared in the S1 and the S2 into different bins, drying and preheating, and extruding by a single-screw extruder;

s4: extruding a heat-resistant layer 1 and a flame-retardant layer 2 of the power tube by a single-screw extruder in a double-layer co-extrusion mode, and heating, melting and plasticizing materials by an extruder screw to be conveyed to a head neck mold;

s5: adding a mixture of 1: 3, forming a stress layer 3 between the heat-resistant layer 1 of the power pipe and the flame-retardant layer 2 of the power pipe in a co-extrusion mode, wherein the stress layer 3 is formed by mixing glass fibers and polyethylene;

the antioxidant in step S1 is prepared as follows:

s21: adding 2, 6-di-tert-butylphenol into a three-neck flask provided with an electric stirrer, a nitrogen guide pipe and a thermometer, introducing nitrogen for purging, controlling the reaction temperature by using water bath, filling paraformaldehyde and a catalyst into a conical flask, placing the conical flask on a magnetic stirrer, stirring, controlling the temperature to be 50 ℃, pouring into a dropping funnel after the paraformaldehyde is completely depolymerized, dropping into the three-neck flask, controlling the dropping speed to be 1 drop/s, reacting for 5 hours, closing nitrogen, fully shaking, performing reduced pressure distillation, recrystallizing, heating by using a heating sleeve until the nitrogen is completely dissolved, cooling, crystallizing for 4 hours, and performing reduced pressure suction filtration to obtain an intermediate A;

s22: adding bisphenol B and anhydrous potassium carbonate into a three-neck flask, adding a stirrer, installing a thermometer, putting the three-neck flask into an oil bath kettle with magnetic stirring, adding triethyl phosphite, connecting a condensing device, starting the magnetic stirring, heating to 120 ℃, starting the reaction, reacting for 3 hours, stopping heating, and after the temperature is reduced, carrying out reduced pressure distillation to obtain an intermediate B;

s23: adding the intermediate A and a catalyst into a three-necked bottle, adding a xylene solvent and a stirrer, putting the three-necked bottle into an oil bath kettle with magnetic stirring, installing a thermometer and a constant-pressure funnel, connecting a condensing device, starting magnetic stirring, heating to 120 ℃, adding the intermediate B, reacting for 3 hours, then carrying out reduced pressure distillation, recrystallization and filtration to obtain the antioxidant;

the preparation steps of the electric power tube flame-retardant layer material in the step S2 are as follows:

s61: adding pyromellitic dianhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked flask provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, heating to 120 ℃, electromagnetically stirring for 15h, pouring the system into distilled water containing concentrated hydrochloric acid, filtering, and washing with distilled water to obtain an intermediate C;

s62: charging intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂Heating to 80 ℃ under stirring, reacting for 8h, and performing rotary evaporation to obtain an intermediate D;

s63: adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, dropwise adding the intermediate D into the three-necked bottle under stirring, controlling the dropwise adding speed to be 2 drops/s, heating to 40 ℃, reacting for 26 hours, pouring into distilled water containing concentrated hydrochloric acid, and placing the distilled water into a drying box at 70 ℃ for vacuum drying for 20 hours to obtain the flame-retardant layer material of the power tube.

Example 3:

the embodiment is an MPP power tube with heat resistance, and the preparation method of the MPP power tube with heat resistance comprises the following steps:

s1: respectively weighing 70 parts of polypropylene, 30 parts of glass fiber, 4 parts of silane coupling agent, 5 parts of stearic acid, 3 parts of paraffin and 2 parts of antioxidant according to parts by weight, and uniformly mixing to obtain a heat-resistant layer blend material of the power pipe;

s2: preparing a flame-retardant layer material of the power tube;

s3: respectively adding the heat-resistant layer blend of the power tube and the flame-retardant layer material of the power tube prepared in the S1 and the S2 into different bins, drying and preheating, and extruding by a single-screw extruder;

s4: extruding a heat-resistant layer 1 and a flame-retardant layer 2 of the power tube by a single-screw extruder in a double-layer co-extrusion mode, and heating, melting and plasticizing materials by an extruder screw to be conveyed to a head neck mold;

s5: adding a mixture of 1: 3, forming a stress layer 3 between the heat-resistant layer 1 of the power pipe and the flame-retardant layer 2 of the power pipe in a co-extrusion mode, wherein the stress layer 3 is formed by mixing glass fibers and polyethylene;

the antioxidant in step S1 is prepared as follows:

s21: adding 2, 6-di-tert-butylphenol into a three-neck flask provided with an electric stirrer, a nitrogen guide pipe and a thermometer, introducing nitrogen for purging, controlling the reaction temperature by using water bath, filling paraformaldehyde and a catalyst into a conical flask, placing the conical flask on a magnetic stirrer, stirring, controlling the temperature to be 60 ℃, pouring into a dropping funnel after the paraformaldehyde is completely depolymerized, dropping into the three-neck flask, controlling the dropping speed to be 2 drops/s, reacting for 6 hours, closing nitrogen, carrying out reduced pressure distillation after full oscillation, recrystallizing, heating by using a heating sleeve until the nitrogen is completely dissolved, cooling, crystallizing for 8 hours, and carrying out reduced pressure suction filtration to obtain an intermediate A;

s22: adding bisphenol B and anhydrous potassium carbonate into a three-neck flask, adding a stirrer, installing a thermometer, putting the three-neck flask into an oil bath kettle with magnetic stirring, adding triethyl phosphite, connecting a condensing device, starting the magnetic stirring, heating to 130 ℃, starting the reaction, reacting for 4 hours, stopping heating, and after the temperature is reduced, carrying out reduced pressure distillation to obtain an intermediate B;

s23: adding the intermediate A and a catalyst into a three-necked bottle, adding a xylene solvent and a stirrer, putting the three-necked bottle into an oil bath kettle with magnetic stirring, installing a thermometer and a constant-pressure funnel, connecting a condensing device, starting magnetic stirring, heating to 130 ℃, adding the intermediate B, reacting for 4 hours, then carrying out reduced pressure distillation, recrystallization and filtration to obtain the antioxidant;

the preparation steps of the electric power tube flame-retardant layer material in the step S2 are as follows:

s61: adding pyromellitic dianhydride, L-phenylalanine, N-dimethylformamide and pyridine into a three-necked flask provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, heating to 130 ℃, electromagnetically stirring for 20 hours, pouring the system into distilled water containing concentrated hydrochloric acid, filtering, and washing with distilled water to obtain an intermediate C;

s62: charging intermediate C and SOCl into a three-necked flask equipped with a stirrer and a reflux condenser₂Heating to 90 ℃ under stirring, reacting for 10h, and performing rotary evaporation to obtain an intermediate D;

s63: adding 1, 4-butynediol, triethylamine and N, N-dimethylacetamide into a three-necked bottle provided with a thermometer, a stirrer, a reflux condenser tube and a nitrogen inlet, introducing nitrogen, dropwise adding the intermediate D into the three-necked bottle under stirring, controlling the dropwise adding speed to be 2 drops/s, heating to 40 ℃, reacting for 26 hours, pouring into distilled water containing concentrated hydrochloric acid, and placing the distilled water into a drying box at 70 ℃ for vacuum drying for 20 hours to obtain the flame-retardant layer material of the power tube.

Comparative example 1:

this comparative example compares to example 1 with no antioxidant added;

comparative example 2:

this comparative example compares with example 1 step S23 without using a catalyst;

the MPP power tubes of the examples 1-3 and the comparative examples 1-2 are subjected to accelerated thermal-oxidative aging test by adopting a universal testing machine according to the GB/T528-2009 standard, setting the tensile rate to be 500mm/min, testing the elongation at break of the material, and carrying out the GB/T3512-2001 standard, wherein the aging temperature is 100 ℃;

the results are shown in the following table:

as can be seen from the above table, under the same test conditions, the elongation at break of the example reaches 372-380%, the elongation at break of the comparative example 1 without the antioxidant is 255%, the elongation at break of the comparative example 2 is 298%, the elongation at break retention of the example with the aging time of 30h reaches 80-82%, the elongation at break retention of the comparative example 1 without the antioxidant with the aging time of 30h is 70%, the elongation at break retention of the comparative example 2 with the aging time of 30h is 78%, the elongation at break retention of the example with the aging time of 60h reaches 70-75%, the elongation at break retention of the comparative example 1 with the antioxidant without the aging time of 60h is 59%, the elongation at break retention of the comparative example 2 with the aging time of 60h is 65%, and the elongation at break retention of the example with the aging time of 90h reaches 68-72%, the elongation at break retention rate of comparative example 1 with aging time of 90h and without adding antioxidant is 54%, the elongation at break retention rate of comparative example 2 with aging time of 90h is 60%, the elongation at break retention rate of example with aging time of 180h reaches 59-62%, the elongation at break retention rate of comparative example 1 with aging time of 180h and without adding antioxidant is 48%, the elongation at break retention rate of comparative example 2 with aging time of 180h is 55%, each data of the examples are obviously superior to the comparative examples, and the antioxidant addition obviously improves the oxidation resistance and the mechanical property of the MPP power tube.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.