A high-strength PE pipe and its preparation method

Abstract

The present invention discloses a high-strength PE pipe and a preparation method thereof, and relates to the technical field of preparation of power cable accessories. A high-strength PE pipe comprises, from the inside to the outside, an inner pipe, a fiber reinforcement layer and a protective layer, wherein the inner pipe comprises high-density polyethylene extruded, the fiber reinforcement layer comprises surface-modified fibers formed by weaving and winding and coating on the outer surface of the inner pipe, and the protective layer comprises an outer layer of protective liquid coated on the outer surface of the fiber reinforcement layer and fully cross-linked and cured. By providing a fiber reinforcement layer, it is beneficial to improve the mechanical properties and ring stiffness of the cable conduit, and the protective layer has excellent impact strength, acid and alkali corrosion resistance, wear resistance and heat resistance, which is not only beneficial to prevent the cable conduit from wear and deformation or rupture due to corrosion, impact, aging and other factors, but also beneficial to improve the comprehensive performance of the cable conduit.

Description

Technical Field

[0001] The present invention relates to the field of cable conduit accessories, and in particular to a high-strength PE pipe and a preparation method thereof. Background Art

[0002] With the development of the power industry, the use of cable conduits has gradually increased. During use, cable conduits are usually buried underground or built into walls. Then, workers will pass wires and cables into the cable conduits and use the cable conduits to fully protect the wires and cables. Therefore, the cable conduits generally have high requirements for wear resistance, impact resistance, corrosion resistance and other properties.

[0003] Currently, most common cable conduits on the market use polyethylene (PE) as their base material and are manufactured through extrusion, resulting in a simple structure. Although PE is an inert material, resistant to various acid and alkali corrosion, lightweight, and inexpensive, its inherent properties result in poor mechanical strength after molding. Under external impact and high pressure, PE pipes are prone to wear, deformation, and even rupture. This not only affects the use of the cable conduit but, in severe cases, can also affect the normal transmission of the wires and cables within, causing breakdown or leakage.

[0004] To improve the mechanical strength of cable conduits, a certain amount of reinforcing filler is generally added to the mixed rubber compound. Currently, steel-plastic composite polyethylene (PE) cable conduits are available on the market. This type of conduit uses a mesh structure woven from metal wire as the cable conduit skeleton and is extruded together with the polyethylene (PE). With the rigidity of the metal wire, the ring stiffness and other mechanical properties of the cable conduit are greatly improved. However, during use, it has been found that this type of cable conduit with a metal skeleton is prone to generating eddy currents between the cable and the cable, causing localized heating, which can easily burn through the polyethylene (PE) and cause the cable to be exposed, posing certain safety hazards. Therefore, in order to eliminate safety hazards, it is of great significance to improve the mechanical strength and overall performance of the polyethylene (PE) cable conduit without using a metal skeleton. Summary of the Invention

[0005] In order to improve the mechanical strength of polyethylene (PE) cable conduits, prevent polyethylene (PE) cable conduits from being easily worn, deformed or ruptured, and improve the comprehensive performance of polyethylene (PE) cable conduits, the present application provides a high-strength PE pipe and a preparation method thereof.

[0006] In the first aspect, the present application provides a high-strength PE pipe adopting the following technical solution:

[0007] A high-strength PE pipe, comprising, from the inside out, an inner pipe, a fiber-reinforced layer, and a protective layer, wherein the inner pipe is made of high-density polyethylene extruded, the fiber-reinforced layer comprises surface-modified fibers braided and wrapped around the outer surface of the inner pipe, and the protective layer comprises an outer layer of protective liquid coated on the outer surface of the fiber-reinforced layer and fully cross-linked and cured;

[0008] The surface modified fiber is selected from any one of modified glass fiber or modified PBO fiber;

[0009] The outer layer protective liquid comprises the following raw materials in parts by weight:

[0010] Vinyl-terminated fluorosilicone oil: 25-30 parts;

[0011] Hydrogen fluorinated silicone oil: 0.6-1.2 parts;

[0012] Platinum catalyst: 0.08-0.13 parts;

[0013] Outer layer filler: 12-18 parts;

[0014] Wherein, the vinyl mass fraction of the vinyl-terminated fluorosilicone oil is 1.2%-1.5%, and the active hydrogen mass fraction of the hydrogen-containing fluorosilicone oil is 0.2%-0.6%;

[0015] The outer layer filler includes fumed silica, or any one or more of ferric oxide and zirconium silicate fully mixed with the fumed silica and obtained by silane coupling treatment.

[0016] By adopting the above technical solution, a surface-modified fiber is wrapped around the inner tube surface to form a fiber reinforcement layer, which significantly improves the mechanical properties and hoop stiffness of the cable conduit. An outer protective liquid is then applied to the surface of the fiber reinforcement layer to form a protective layer. The outer protective liquid fully penetrates the fiber reinforcement layer, allowing it to adhere to the inner tube and effectively enhance the fiber reinforcement layer. Furthermore, under the initiation and catalysis of the hydrogenated fluorosilicone oil and platinum catalyst, the vinyl-terminated fluorosilicone oil undergoes a cross-linking reaction to form a high-strength organic fluorosilicone rubber protective layer on the surface of the fiber reinforcement layer. Combined with the reinforcement of the outer filler layer, the protective layer possesses excellent impact strength, acid and alkali corrosion resistance, wear resistance, and thermal resistance. This helps prevent the cable conduit from wear and deformation, or rupture due to corrosion, impact, aging, and other factors, thereby improving the overall performance of the cable conduit.

[0017] Optionally, the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is 0.2%-0.4%.

[0018] By adopting the above technical solution, when the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is within the range of 0.2%-0.4%, the cross-linking degree of the protective layer is relatively appropriate, and it has good hardness, wear resistance and strength, and better overall performance. This is not only beneficial to improving the ring stiffness and surface wear resistance of the cable conduit, but also can prevent the cable conduit from losing strength due to excessive cross-linking of the protective layer, which is beneficial for the cable conduit to have good mechanical strength.

[0019] Optionally, the outer layer filler is a mixture of the fumed silica, the ferric oxide and the zirconium silicate, and the mixing weight ratio of the fumed silica, the ferric oxide and the zirconium silicate is 1: (0.2-0.4): (0.1-0.15).

[0020] By adopting the above technical solution, when the mixing weight ratio of fumed silica, ferric oxide and zirconium silicate is within the range of 1: (0.2-0.4): (0.1-0.15), ferric oxide and zirconium silicate can cooperate with each other to further improve the heat resistance and wear resistance of the protective layer. Combined with the reinforcing effect of fumed silica, the surface wear resistance, ring stiffness and heat aging resistance of the cable conduit can be effectively improved, which is conducive to improving the overall performance of the cable conduit.

[0021] Optionally, the silane coupling treatment of the outer layer filler comprises the following steps:

[0022] D1. Add KH560 silane coupling agent to a certain concentration of ethanol solution, then heat to 40-50°C and continue to react for 60-90 minutes. Finally, slowly add the outer layer filler, maintain the temperature and continue stirring to react for 30-60 minutes, and filter to obtain the silane-coupled outer layer filler.

[0023] By adopting the above technical solution, the KH560 silane coupling agent is first heated using an ethanol solution of a certain concentration, so that the KH560 silane coupling agent can be fully hydrolyzed and fully generate silanol groups, so that the outer layer filler can be fully combined with the KH560 silane coupling agent, which is beneficial to further improve the interfacial compatibility of the outer layer filler and enable the outer layer filler to be fully dispersed in the outer layer protective liquid, thereby helping to fully improve the strength of the protective layer.

[0024] Optionally, the modification of the modified glass fiber comprises the following steps:

[0025] Ca1. First, fully soak and clean the glass fiber with anhydrous ethanol. After drying, fully immerse the glass fiber in a mixed acid solution, heat and continuously stir the reaction for 30-40 minutes, then take it out, and then soak and clean it with distilled water several times until the cleaning solution is neutral. After drying, obtain the acid-etched glass fiber;

[0026] Ca2. Soak the acid-etched glass fiber obtained in step Ca1 in KH570 silane coupling agent, heat and continuously stir to react for 15-20 minutes, then take it out and dry it to obtain the modified glass fiber.

[0027] By adopting the above technical solution, using a mixed acid solution to acid-etch the glass fiber, metal oxide impurities such as Al2O3, MgO, and Na2O on the surface of the glass fiber can be fully dissolved, forming a certain depression on the surface of the glass fiber, thereby fully anchoring and bonding with the silane coupling agent, improving the interfacial compatibility of the glass fiber, and facilitating the outer protective liquid to fully penetrate the fiber reinforcement layer and fully adhere to the inner tube. After the outer protective liquid is fully cross-linked and cured, the formed protective layer can fully adhere to and cover the glass fiber on the outer surface of the inner tube, forming an integrated cable conduit. In addition, the glass fiber has a certain mechanical strength, which helps to improve the ring stiffness and strength of the cable conduit.

[0028] Optionally, the surface-modified fiber is a modified PBO fiber, and the modification of the modified PBO fiber comprises the following steps:

[0029] Cb1. First, the PBO fiber is thoroughly soaked and cleaned with anhydrous ethanol. After drying, the PBO fiber is fully immersed in a mixed solution of polyphosphoric acid / acetic acid at a certain concentration. The mixture is stirred for 2-6 minutes and then taken out. The PBO fiber is then soaked and cleaned multiple times with a weak base and distilled water until the cleaning solution becomes neutral. After drying, the acid-etched PBO fiber is obtained.

[0030] Cb2. Immerse the acid-etched PBO fiber obtained in step Cb1 in heptafluorodecyltrichlorosilane, heat to 40-50° C., and continue stirring for 10-20 minutes before taking it out and drying it to obtain the modified PBO fiber.

[0031] By adopting the above technical solution, acid-etching the PBO fiber with a polyphosphoric acid / acetic acid mixed solution creates acid-etched pits on the smooth PBO fiber surface, making the PBO fiber very rough. Then, immersing the PBO fiber in heptadecafluorodecyltrichlorosilane effectively increases the number of polar functional groups on the PBO limiting surface, thereby improving the compatibility between the PBO fiber and the outer protective liquid. This facilitates the outer protective liquid to fully penetrate the fiber reinforcement layer and adhere to the inner tube. After the outer protective liquid is fully crosslinked and cured, the formed protective layer can fully adhere to the fiber reinforcement layer and coat the outer surface of the inner tube, forming an integrated cable conduit. Furthermore, PBO fiber itself has very high stiffness and strength, which helps further improve the hoop stiffness and strength of the cable conduit compared to glass fiber.

[0032] Optionally, the inner tube comprises the following raw materials in parts by weight:

[0033] High-density polyethylene: 80-100 parts;

[0034] Silane crosslinker: 1.2-2 parts;

[0035] Peroxide initiator: 0.06-0.12 parts;

[0036] Catalyst: 0.1-0.2 parts;

[0037] Antioxidant: 0.4-0.6 parts;

[0038] Stearic acid: 2-4 parts;

[0039] Boron nitride: 8-12 parts;

[0040] Silane coupling agent: 2-4 parts;

[0041] The silane crosslinking agent includes any one of vinyltrimethoxysilane and vinyltriethoxysilane; the peroxide initiator includes any one of dibenzoyl peroxide and dicumyl peroxide.

[0042] By adopting the above technical solution, the molecular segments of the high-density polyethylene (HDPE) are cross-linked using a silane crosslinker, a peroxide initiator, and a catalyst, effectively improving the strength of the inner tube. Furthermore, the addition of a small amount of stearic acid improves the toughness of the inner tube, thereby increasing its impact strength. The addition of boron nitride primarily enhances insulation and provides reinforcement, not only improving the electrical insulation of the inner tube, but also making it more suitable for cable routing, preventing breakdown, and enhancing the mechanical strength of the cable conduit.

[0043] Optionally, the antioxidant comprises an antioxidant 1010 and an antioxidant 168 mixed in proportion, and the mixing weight ratio of the antioxidant 1010 to the antioxidant 168 is 1:(1.5-2).

[0044] By adopting the above technical solution, when the antioxidant in the inner tube is selected from antioxidant 1010 and antioxidant 168, which are mixed with each other and the mixing weight ratio is within the range of 1: (1.5-2), a certain synergistic effect can be produced between antioxidant 1010 and antioxidant 168, so that the inner tube has better antioxidant properties, which is beneficial for the cable conduit to still have good mechanical strength after a long period of thermal aging.

[0045] Optionally, the boron nitride is subjected to a hydroxylation treatment before being added and mixed, and the hydroxylation treatment comprises the following steps:

[0046] B1. First, soak the boron nitride in an acidic solution, heat it to 70-85°C, fully stir and react for 5-8 hours, filter to obtain a filter residue, and then repeatedly soak and filter the filter residue with water until the filtrate is neutral. The final filtered residue is acid-treated boron nitride;

[0047] B2. Soak the acid-treated boron nitride obtained in step B1 in a 3-glycidyl propoxytrimethoxysilane solution, heat to 80-110° C., fully stir and soak for 4-6 hours, take out and dry to obtain hydroxylated modified boron nitride.

[0048] By adopting the above technical solution, the boron nitride is acidified using an acidic solution, which can produce acid-etched pits on the surface of the boron nitride, thereby increasing the specific surface area of ​​the boron nitride. The boron nitride is then immersed in a 3-glycidylpropoxytrimethoxysilane solution, so that a large number of hydroxyl reaction sites can be connected to the surface of the boron nitride. This is conducive to the full reaction and grafting of the boron nitride and the silane coupling agent. It not only fully improves the interfacial compatibility of the boron nitride and enables the boron nitride to be fully dispersed in the system, but also helps to increase the bonding strength between the boron nitride and polyethylene, which helps to further improve the mechanical strength of the inner tube, and thus makes the cable conduit have higher impact strength and tensile strength.

[0049] In a second aspect, the present application provides a method for preparing a high-strength PE pipe using the following technical solutions:

[0050] A method for preparing a high-strength PE pipe comprises the following steps:

[0051] S1. First, high-density polyethylene is divided into AI material and BI material in a ratio of (9-9.5): (0.5-1), a silane crosslinker and a peroxide initiator are added to the AI ​​material, and the mixture is fully mixed to obtain AII material, a catalyst, stearic acid and an antioxidant are added to the BI material, and the mixture is fully mixed to obtain BII material, and the AII material and BII material are respectively granulated by melt extrusion to obtain AIII material and BIII material;

[0052] S2. Fully mix the AIII material, the BIII material, the silane coupling agent and the boron nitride, and then extrude the inner tube semi-finished product;

[0053] S3, the inner tube semi-finished product obtained in step S2 is fumigated with water vapor for 18-24 hours, then taken out and dried to obtain the inner tube;

[0054] S4, using surface-modified PBO fibers to weave and wrap around the inner tube surface to form a fiber reinforcement layer of a certain thickness;

[0055] S5. Fully mix the vinyl-terminated fluorosilicone oil, hydrogen-containing fluorosilicone oil, platinum catalyst and outer filler to obtain an outer protective liquid, and fully apply the outer protective liquid to the surface of the fiber reinforcement layer. During the coating, the inner tube is continuously rotated around the central axis, and then maintained in rotation and cured at 50-60° C. for 2-4 hours to form a protective layer with a smooth surface, thereby obtaining a cable conduit.

[0056] By adopting the above technical solution, an inner tube is first prepared, and then surface-modified fibers are directly woven and wound on the surface of the inner tube to form a fiber reinforcement layer. Finally, an outer layer of protective liquid is coated on the fiber reinforcement layer. After heating and curing, a cable conduit is obtained. The production process is simple, and the protective layer is formed by chemical cross-linking and curing. The required equipment investment is small and the cost is low, which is conducive to subsequent mass production.

[0057] In summary, the technical solution of this application has at least one of the following beneficial effects:

[0058] 1. By winding a surface-modified fibrous fiber reinforcement layer on the surface of the inner tube, it is beneficial to improve the mechanical properties and ring stiffness of the cable conduit.

[0059] 2. By further coating the surface of the fiber-reinforced layer with an outer protective liquid to form a protective layer, the outer protective liquid can fully penetrate into the fiber-reinforced layer, so that it can fully adhere to the inner tube, which is beneficial for the fiber-reinforced layer to fully exert its reinforcing effect. In addition, the protective layer has excellent impact strength, acid and alkali corrosion resistance, wear resistance and heat resistance, which is beneficial for preventing the cable conduit from wear and deformation or rupture due to corrosion, impact, aging and other factors, and is beneficial for improving the comprehensive performance of the cable conduit. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a cross-sectional view of a high-strength PE pipe in embodiment 1 of the present application.

[0061] Description of reference numerals:

[0062] 1. Inner tube; 2. Fiber reinforcement layer; 3. Protective layer. DETAILED DESCRIPTION

[0063] The present application is further described in detail below with reference to the accompanying drawings, preparation examples, embodiments and comparative examples.

[0064] High-density polyethylene was purchased from Yanshan Petrochemical, with a brand name of 6380M. The high-density polyethylene of this brand has a melt flow rate of 0.5 g / 10 min, a density of 0.949 g / cm3, a yield tensile strength ≥22 MPa, a break tensile strength ≥33 MPa, and a tensile modulus of 800 MPa.

[0065] The vinyl-terminated fluorosilicone oil was purchased from Fuzhou Taipuda New Materials Co., Ltd. with the brand name TPD-FS8019-300. The viscosity of the vinyl-terminated fluorosilicone oil at 25°C is 300 mm2 / s, and the vinyl mass fraction is 1.2%-1.5%. The specific vinyl mass fraction is prepared by communication with the merchant.

[0066] The hydrofluorosilicone oils were purchased from Xinyuan Chemical (Shandong) Co., Ltd., with the brands NFS7401, NFS7402, and NFS7403, where the active hydrogen mass fractions corresponding to the three brands are 2%, 4%, and 6%, respectively.

[0067] Boron nitride was purchased from Shandong Jingyi New Materials Co., Ltd., model SW, specifically hexagonal boron nitride with a particle size in the range of 2-20 μm.

[0068] Preparation Example

[0069] [Preparation Example 1-1]

[0070] An inner tube 1 of a high-strength PE pipe comprises the following raw materials:

[0071] 100kg high-density polyethylene, 1.6kg silane crosslinker, 0.1kg peroxide initiator, 0.14kg catalyst, 0.6kg antioxidant, 3kg stearic acid, 10kg boron nitride, 4kg silane coupling agent.

[0072] The silane crosslinking agent is vinyltrimethoxysilane, the initiator is dibenzoyl peroxide, the catalyst is dibutyltin dilaurate, the antioxidant is antioxidant 1010, and the silane coupling agent is KH570 silane coupling agent.

[0073] A method for preparing an inner tube 1 of a high-strength PE pipe comprises the following steps:

[0074] A1, first high-density polyethylene is divided into AI material and BI material according to the ratio of 9.5:0.5, silane crosslinking agent and peroxide initiator are added to the AI ​​material, and fully mixed to obtain AII material, catalyst, stearic acid and antioxidant are added to the BI material, and fully mixed to obtain BII material, and the AII material and BII material are respectively granulated by melt extrusion to obtain AIII material and BIII material;

[0075] A2, fully mixing material AIII, material BIII, a silane coupling agent and boron nitride, and then extruding to obtain a semi-finished inner tube 1;

[0076] A3. The semi-finished inner tube 1 obtained in step S2 is fumigated with water vapor for 24 hours, taken out, and then dried to obtain the inner tube 1.

[0077] [Preparation Example 1-2]

[0078] An inner tube 1 of a high-strength PE pipe comprises the following raw materials:

[0079] High-density polyethylene 80kg, silane crosslinker 1.2kg, peroxide initiator 0.06kg, catalyst 0.2kg, antioxidant 0.4kg, stearic acid 2kg, boron nitride 12kg, silane coupling agent 3kg.

[0080] The silane crosslinking agent is vinyl triethoxysilane, the initiator is dibenzoyl peroxide, the catalyst is dibutyltin dilaurate, the antioxidant is antioxidant 1010, and the silane coupling agent is KH570 silane coupling agent.

[0081] A method for preparing an inner tube 1 of a high-strength PE pipe comprises the following steps:

[0082] A1. First, high-density polyethylene is divided into AI material and BI material in a ratio of 9:1, a silane crosslinker and a peroxide initiator are added to the AI ​​material, and the mixture is thoroughly mixed to obtain AII material. A catalyst, stearic acid and an antioxidant are added to the BI material, and the mixture is thoroughly mixed to obtain BII material. The AII material and the BII material are respectively granulated by melt extrusion to obtain AIII material and BIII material;

[0083] A2, fully mixing material AIII, material BIII, a silane coupling agent and boron nitride, and then extruding to obtain a semi-finished inner tube 1;

[0084] A3. The semi-finished inner tube 1 obtained in step S2 is fumigated with water vapor for 18 hours, taken out, and then dried to obtain the inner tube 1.

[0085] [Preparation Examples 1-3]

[0086] An inner tube 1 of a high-strength PE pipe comprises the following raw materials:

[0087] 90kg high-density polyethylene, 2kg silane crosslinker, 0.12kg peroxide initiator, 0.1kg catalyst, 0.5kg antioxidant, 4kg stearic acid, 8kg boron nitride, and 2kg silane coupling agent.

[0088] The silane crosslinking agent is vinyltrimethoxysilane, the initiator is dicumyl peroxide, the catalyst is dibutyltin dilaurate, and the silane coupling agent is KH570 silane coupling agent.

[0089] In this preparation example, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168. Specifically, the mixing weight ratio of antioxidant 1010 to antioxidant 168 is 2:3, that is, in this preparation example, the added amount of antioxidant 1010 is 0.2 kg, and the added amount of antioxidant 168 is 0.3 kg.

[0090] A method for preparing an inner tube 1 of a high-strength PE pipe comprises the following steps:

[0091] A1, first high-density polyethylene is divided into AI material and BI material according to the ratio of 9.5:0.5, silane crosslinking agent and peroxide initiator are added to the AI ​​material, and fully mixed to obtain AII material, catalyst, stearic acid and antioxidant are added to the BI material, and fully mixed to obtain BII material, and the AII material and BII material are respectively granulated by melt extrusion to obtain AIII material and BIII material;

[0092] A2, fully mixing material AIII, material BIII, a silane coupling agent and boron nitride, and then extruding to obtain a semi-finished inner tube 1;

[0093] A3. The semi-finished inner tube 1 obtained in step S2 is fumigated with water vapor for 20 hours, taken out, and then dried to obtain the inner tube 1.

[0094] [Preparation Examples 1-4]

[0095] An inner tube 1 of a high-strength PE pipe differs from [Preparation Example 1-1] in that the type of antioxidant is different.

[0096] In this preparation example, the antioxidant was replaced by antioxidant 168 in equal amount, that is, in this preparation example, the added amount of antioxidant 168 was 0.6 kg.

[0097] [Preparation Examples 1-5]

[0098] An inner tube 1 of a high-strength PE pipe differs from [Preparation Example 1-1] in that the type of antioxidant is different.

[0099] In this preparation example, the antioxidant is replaced by an equal amount of a mixture of antioxidant 1010 and antioxidant 168. Specifically, the mixing weight ratio of antioxidant 1010 to antioxidant 168 is 1:2, that is, in this preparation example, the added amount of antioxidant 1010 is 0.2 kg, and the added amount of antioxidant 168 is 0.4 kg.

[0100] [Preparation Example 1-6]

[0101] An inner tube 1 of a high-strength PE pipe differs from [Preparation Example 1-1] in that the boron nitride is hydroxylated before being mixed and added, wherein the hydroxylation modification step of the boron nitride includes:

[0102] B1. First, the boron nitride is immersed in a mixed acidic solution, wherein the mixed acidic solution comprises a mixture of 10% nitric acid solution and 5% sulfuric acid solution, heated to 85° C., stirred and reacted for 8 hours, filtered to obtain a filter residue, and then repeatedly immersed and filtered the filter residue with water until the filtrate is neutral, and the final filtered filter residue is acid-treated boron nitride;

[0103] B2. Soak the acid-treated boron nitride obtained in step B1 in a 3-glycidylpropoxytrimethoxysilane solution, heat to 110° C., fully stir and soak for 4 hours, take out and dry to obtain hydroxylated modified boron nitride.

[0104] [Preparation Example 2-1]

[0105] A surface-modified fiber is prepared by modifying glass fiber, wherein the modification of the glass fiber comprises the following steps:

[0106] Ca1. First, the glass fiber is fully soaked and cleaned with anhydrous ethanol. After drying, the glass fiber is fully immersed in a mixed acid solution, wherein the mixed acid solution includes a mixture of a 10% nitric acid solution and a 5% sulfuric acid solution, heated to 85°C, stirred and reacted for 30 minutes, and then taken out. Then, it is soaked and cleaned with distilled water for multiple times until the cleaning solution is neutral. After drying, the acid-etched glass fiber is obtained;

[0107] Ca2. Soak the acid-etched glass fiber obtained in step Ca1 in KH570 silane coupling agent, heat to 50° C. and continue stirring for 15 minutes, then take it out and dry it to obtain the modified glass fiber.

[0108] [Preparation Example 2-2]

[0109] A surface-modified fiber is prepared by modifying PBO fiber, wherein the modification of the PBO fiber comprises the following steps:

[0110] Cb1. First, the PBO fiber is thoroughly soaked and cleaned with anhydrous ethanol. After drying, the PBO fiber is fully immersed in a mixed solution of acetic acid as a solvent and polyphosphoric acid as a solute, and the concentration of polyphosphoric acid is 50%. The reaction is continuously stirred at room temperature for 4 minutes, and then the fiber is taken out and soaked and cleaned with distilled water multiple times until the cleaning solution is neutral. After drying, the acid-etched PBO fiber is obtained;

[0111] Cb2. Immerse the acid-etched PBO fiber obtained in step C1 in heptafluorodecyltrichlorosilane, heat to 50° C., and continue stirring for 10 minutes before taking it out and drying it to obtain the modified PBO fiber.

[0112] [Preparation Example 3-1]

[0113] An outer protective liquid for a high-strength PE pipe, comprising the following raw materials:

[0114] 28kg of vinyl-terminated fluorosilicone oil, 1kg of hydrogen-containing fluorosilicone oil, 0.1kg of platinum catalyst, and 18kg of outer layer filler.

[0115] Among them, the vinyl mass fraction of the vinyl-terminated fluorosilicone oil is 1.5%; the hydrogen-containing fluorosilicone oil is brand NFS7401, and the active hydrogen mass fraction of this brand of hydrogen-containing fluorosilicone oil is 2%; the platinum catalyst is chloroplatinic acid, and the outer layer filler is fumed silica.

[0116] The outer filler is subjected to silane coupling treatment, which includes the following steps:

[0117] D1. Add KH560 silane coupling agent to 95% ethanol solution, then heat to 50°C and continue to react for 60 minutes. Finally, slowly add the outer layer filler, maintain the temperature and continue stirring to react for 60 minutes, and filter to obtain the silane-coupled outer layer filler.

[0118] A method for preparing an outer layer protective liquid for a high-strength PE pipe comprises the following steps:

[0119] E1. Fully mix the vinyl-terminated fluorosilicone oil, hydrogen-containing fluorosilicone oil, platinum catalyst and silane coupling-treated outer layer filler to obtain an outer layer protective liquid.

[0120] [Preparation Example 3-2]

[0121] An outer protective liquid for a high-strength PE pipe, comprising the following raw materials:

[0122] 25kg of vinyl-terminated fluorosilicone oil, 0.6kg of hydrogen-containing fluorosilicone oil, 0.13kg of platinum catalyst, and 14kg of outer layer filler.

[0123] Among them, the vinyl mass fraction of the vinyl-terminated fluorosilicone oil is 1.2%; the hydrogen-containing fluorosilicone oil is brand NFS7402, and the active hydrogen mass fraction of this brand of hydrogen-containing fluorosilicone oil is 4%; the platinum catalyst is chloroplatinic acid, and the outer layer filler is fumed silica.

[0124] The outer filler is subjected to silane coupling treatment, which includes the following steps:

[0125] D1. Add KH560 silane coupling agent to 95% ethanol solution, then heat to 40°C and continue to react for 90 minutes. Finally, slowly add the outer layer filler, maintain the temperature and continue stirring to react for 60 minutes, and filter to obtain the silane-coupled outer layer filler.

[0126] A method for preparing an outer layer protective liquid for a high-strength PE pipe comprises the following steps:

[0127] E1. Fully mix the vinyl-terminated fluorosilicone oil, hydrogen-containing fluorosilicone oil, platinum catalyst and silane coupling-treated outer layer filler to obtain an outer layer protective liquid.

[0128] [Preparation Example 3-3]

[0129] An outer protective liquid for a high-strength PE pipe, comprising the following raw materials:

[0130] 30kg of vinyl-terminated fluorosilicone oil, 1.2kg of hydrogen-containing fluorosilicone oil, 0.08kg of platinum catalyst, and 15.5kg of outer layer filler.

[0131] Among them, the vinyl mass fraction of the vinyl-terminated fluorosilicone oil is 1.5%; the hydrogen-containing fluorosilicone oil is brand NFS7403, wherein the active hydrogen mass fraction of the hydrogen-containing fluorosilicone oil is 6%; and the platinum catalyst is chloroplatinic acid.

[0132] The outer layer filler is a mixture of fumed silica and zirconium silicate. Specifically, the fumed silica and zirconium silicate are mixed in a weight ratio of 1:0.107, that is, the added amount of fumed silica is 14 kg and the added amount of zirconium silicate is 1.5 kg.

[0133] The outer filler is subjected to silane coupling treatment, which includes the following steps:

[0134] D1. Add KH560 silane coupling agent to 95% ethanol solution, then heat to 45°C and continue to react for 90 minutes. Finally, slowly add the outer layer filler, maintain the temperature and continue stirring to react for 60 minutes, and filter to obtain the silane-coupled outer layer filler.

[0135] A method for preparing an outer layer protective liquid for a high-strength PE pipe comprises the following steps:

[0136] E1. Fully mix the vinyl-terminated fluorosilicone oil, hydrogen-containing fluorosilicone oil, platinum catalyst and silane coupling-treated outer layer filler to obtain an outer layer protective liquid.

[0137] [Preparation Example 3-4]

[0138] A protective liquid for the outer layer of a high-strength PE pipe, which differs from [Preparation Example 3-1] in that it contains a different composition of hydrogen fluorosilicone oil.

[0139] In this preparation example, the hydrogen-containing fluorosilicone oil is selected from the brand NFS7402, wherein the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is 4%.

[0140] [Preparation Example 3-5]

[0141] A protective liquid for the outer layer of a high-strength PE pipe, which differs from [Preparation Example 3-1] in that it contains a different composition of hydrogen fluorosilicone oil.

[0142] In this preparation example, the hydrogen-containing fluorosilicone oil is selected from the brand NFS7403, wherein the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is 6%.

[0143] [Preparation Example 3-6]

[0144] A protective liquid for the outer layer of a high-strength PE pipe, which differs from [Preparation Example 3-4] in that the composition of the outer layer filler is different.

[0145] In this preparation example, the amount of outer layer filler added is 18 kg, and the outer layer filler is a mixture of fumed silica and ferric oxide. Specifically, fumed silica and ferric oxide are mixed in a weight ratio of 1:0.3, that is, the amount of fumed silica added is 14 kg, and the amount of ferric oxide added is 4 kg.

[0146] [Preparation Example 3-7]

[0147] A protective liquid for the outer layer of a high-strength PE pipe, which differs from [Preparation Example 3-4] in that the composition of the outer layer filler is different.

[0148] In this preparation example, the amount of outer layer filler added is 18 kg, and the outer layer filler is a mixture of fumed silica, ferric oxide and zirconium silicate. Specifically, fumed silica and ferric oxide are mixed in a weight ratio of 1:0.375:0.125, that is, the amount of fumed silica added is 12 kg, the amount of ferric oxide added is 4.5 kg, and the amount of zirconium silicate added is 1.5 kg. Example

[0149] [Example 1]

[0150] A high-strength PE pipe comprises, from the inside to the outside, an inner pipe 1, a fiber-reinforced layer 2, and a protective layer 3, wherein the inner pipe 1 is the inner pipe 1 prepared in [Preparation Example 1-1], the fiber-reinforced layer 2 is the surface-modified fiber prepared in [Preparation Example 2-1], which is braided and wrapped around the outer surface of the inner pipe 1, and the protective layer 3 is the outer layer protective liquid prepared in [Preparation Example 3-1], which is coated on the outer surface of the fiber-reinforced layer 2 and fully cross-linked and cured to form a Figure 1 Cable guide shown.

[0151] A high-strength PE pipe comprises the following steps:

[0152] S1. First, the surface-modified fiber is braided and wound around the surface of the inner tube 1 to form a fiber-reinforced layer 2 with an average thickness of 1-2 mm;

[0153] S2. Then, the outer layer of protective liquid is fully coated on the outer surface of the fiber reinforced layer 2. During coating, the inner tube 1 is continuously rotated around the central axis to allow the outer layer of protective liquid to fully penetrate into the fiber reinforced layer 2. Then, the inner tube 1 is kept rotating and cured at 55°C for 2 hours. Finally, a protective layer 3 with a smooth surface and an average thickness of 2-3 mm is formed to obtain a cable conduit.

[0154] [Example 2]

[0155] A high-strength PE pipe comprises, from the inside to the outside, an inner pipe 1, a fiber-reinforced layer 2, and a protective layer 3, wherein the inner pipe 1 is the inner pipe 1 prepared in [Preparation Example 1-2], the fiber-reinforced layer 2 is the surface-modified fiber prepared in [Preparation Example 2-2], which is braided and wrapped around the outer surface of the inner pipe 1, and the protective layer 3 is the outer layer protective liquid prepared in [Preparation Example 3-2], which is coated on the outer surface of the fiber-reinforced layer 2 and fully cross-linked and cured to form a Figure 1 Cable guide shown.

[0156] A high-strength PE pipe comprises the following steps:

[0157] S1. First, the surface-modified fiber is braided and wound around the surface of the inner tube 1 to form a fiber-reinforced layer 2 with an average thickness of 1-2 mm;

[0158] S2. Then, the outer layer of protective liquid is fully coated on the outer surface of the fiber reinforced layer 2. During coating, the inner tube 1 is continuously rotated around the central axis to allow the outer layer of protective liquid to fully penetrate into the fiber reinforced layer 2. Then, the inner tube 1 is kept rotating and cured at 50°C for 4 hours. Finally, a protective layer 3 with a smooth surface and an average thickness of 2-3 mm is formed to obtain a cable conduit.

[0159] [Example 3]

[0160] A high-strength PE pipe comprises, from the inside to the outside, an inner pipe 1, a fiber-reinforced layer 2, and a protective layer 3, wherein the inner pipe 1 is selected from the inner pipe 1 prepared in [Preparation Example 1-3], the fiber-reinforced layer 2 is selected from the surface-modified fiber prepared in [Preparation Example 2-1], and is formed by weaving and winding the surface of the inner pipe 1, and the protective layer 3 is selected from the outer layer protective liquid prepared in [Preparation Example 3-3], which is coated on the outer surface of the fiber-reinforced layer 2 and fully cross-linked and cured to form a Figure 1 Cable guide shown.

[0161] A high-strength PE pipe comprises the following steps:

[0162] S1. First, the surface-modified fiber is braided and wound around the surface of the inner tube 1 to form a fiber-reinforced layer 2 with an average thickness of 1-2 mm;

[0163] S2. Then, the outer layer of protective liquid is fully coated on the outer surface of the fiber reinforced layer 2. During coating, the inner tube 1 is continuously rotated around the central axis to allow the outer layer of protective liquid to fully penetrate into the fiber reinforced layer 2. Then, the inner tube 1 is kept rotating and cured at 60°C for 2 hours. Finally, a protective layer 3 with a smooth surface and an average thickness of 2-3 mm is formed, thereby obtaining a cable conduit.

[0164] [Example 4]

[0165] A high-strength PE pipe, which differs from [Example 1] in that the inner pipe 1 is the inner pipe 1 prepared in [Preparation Example 1-4].

[0166] [Example 5]

[0167] A high-strength PE pipe, which differs from [Example 1] in that the inner pipe 1 is the inner pipe 1 prepared in [Preparation Example 1-5].

[0168] [Example 6]

[0169] A high-strength PE pipe, which differs from [Example 5] in that the inner pipe 1 is the inner pipe 1 prepared in [Preparation Example 1-6].

[0170] [Example 7]

[0171] A high-strength PE pipe, which differs from [Example 6] in that the fiber reinforcement layer 2 uses the surface-modified fiber prepared in [Preparation Example 2-2].

[0172] [Example 8]

[0173] A high-strength PE pipe, which differs from [Example 7] in that: the protective layer 3 is formed by coating the outer layer protective liquid prepared in [Preparation Example 3-4] on the surface of the fiber reinforced layer 2 and curing it through cross-linking.

[0174] [Example 9]

[0175] A high-strength PE pipe, which differs from [Example 7] in that: the protective layer 3 is formed by coating the outer layer protective liquid prepared in [Preparation Example 3-5] on the surface of the fiber reinforced layer 2 and curing it through cross-linking.

[0176] [Example 10]

[0177] A high-strength PE pipe, which differs from [Example 8] in that: the protective layer 3 is formed by coating the outer layer protective liquid prepared in [Preparation Example 3-6] on the surface of the fiber reinforced layer 2 and curing it through cross-linking.

[0178] [Example 11]

[0179] A high-strength PE pipe, which differs from [Example 8] in that: the protective layer 3 is formed by coating the outer layer protective liquid prepared in [Preparation Example 3-7] on the surface of the fiber reinforced layer 2 and curing through cross-linking. Comparative Example

[0180] [Comparative Example 1]

[0181] A PE pipe, which differs from [Example 1] in that it does not have a fiber reinforcement layer 2 and a protective layer 3.

[0182] [Comparative Example 2]

[0183] A PE pipe, which differs from [Example 1] in that it does not have a fiber reinforcement layer 2.

[0184] [Comparative Example 3]

[0185] A PE pipe, which differs from [Example 1] in that it does not have a protective layer 3.

[0186] Performance test data

[0187] 1. Impact resistance test: Perform a single notch impact test according to the requirements of specimen type 6 in Method B of GB / T 18743.1-2022 Thermoplastic plastics pipes - Determination of impact strength of simply supported beams - Part 1: General test method and GB / T 18743.2-2022 Thermoplastic plastics pipes - Determination of impact strength of simply supported beams - Part 2: Test conditions for pipes of different materials, and record the average impact strength.

[0188] 2. Surface wear resistance test: The test was conducted according to the Taber wear test. The sample was fixed on a rotating platform with the outer surface of the sample facing upward. Two grinding wheels were lowered with a certain load so that they just touched the surface of the sample. The speed was set to 60 r / min. The CS-10 grinding wheel was selected for the grinding wheel. The test time was 1 hour. The weight loss of the samples after wear of the embodiment and the comparative example was recorded.

[0189] 3. Compression resistance test: Ring stiffness test was performed according to Section 6.4 of T / SGX 009-2021 High-density polyethylene (HDPE) plastic casing for buried power cables and GB / T 9647-2015 Determination of ring stiffness of thermoplastic plastic pipes, and the ring stiffness of each embodiment and comparative example was recorded.

[0190] 4. Heat aging resistance test: The test is conducted according to the tensile test procedure in Section 9.1.7 of GB / T 2951.12-2008 General test methods for insulation and sheathing materials of electric cables and optical cables - Part 11: General test methods for thickness and dimensions - Mechanical properties test. Then, the heat aging test is conducted according to GB / T 2951.11-2008 General test methods for insulation and sheathing materials of electric cables and optical cables - Part 12: General test methods for thermal aging test. The specimens are heat aged in a tubular form and baked in circulating hot air at 70°C for 240 hours. The tensile strength (MPa) before and after the heat aging treatment is recorded.

[0191] Table 1 Test data of pipe physical properties

[0192]

[0193] Table 2 Test data of pipe heat aging resistance

[0194]

[0195] Combining Example 1 with Comparative Examples 1-3 and the data in Tables 1 and 2, it can be seen that by winding the surface-modified fibrous fiber-forming fiber reinforcement layer 2 on the surface of the inner tube 1 and then further coating the surface of the fiber reinforcement layer 2 with an outer protective liquid made of silicone oil to form a protective layer 3, the impact strength, tensile strength, wear resistance and ring stiffness of the cable conduit can be effectively improved.

[0196] Among them, the fiber reinforced layer 2 can greatly improve the mechanical properties of the cable conduit, and the protective layer 3 can further reinforce the fiber reinforced layer 2, so that the fiber reinforced layer 2 is fully attached to the inner tube 1, which is beneficial for the fiber reinforced layer 2 to fully exert its reinforcing effect. This may be because the fibers in the fiber reinforced layer 2 have improved the interface compatibility between the fibers and the outer protective liquid through surface modification, so that when the outer protective liquid is applied, the outer protective liquid can fully penetrate into the fiber reinforced layer 2 and fully adhere to the inner tube 1. After the outer protective liquid is fully cross-linked and cured, the protective layer 3 formed can fully adhere and cover the fiber reinforced layer 2 on the outer surface of the inner tube 1 to form an integrated cable conduit.

[0197] Among them, protective layer 3 can improve the surface wear resistance of the cable conduit. This may be because the vinyl-terminated fluorosilicone oil undergoes a cross-linking reaction under the action of hydrogen-containing fluorosilicone oil and platinum catalyst to form an organic silicone rubber with a certain three-dimensional structure. The cross-linked and cured organic silicone rubber exhibits a high-strength elastomer with excellent toughness and wear resistance, which is beneficial to improving the overall impact strength and surface wear resistance of the cable conduit.

[0198] However, without the fiber-reinforced layer 2, the protective layer 3 lacks the strength to support the cable conduit, and therefore has little impact on the overall hoop stiffness of the cable conduit. However, when the protective layer 3 is used in conjunction with the fiber-reinforced layer 2, the fibers provide support for the protective layer 3, while the protective layer 3 further reinforces the fiber-reinforced layer 2. The fiber-reinforced layer 2 and the protective layer 3 create a synergistic effect, further enhancing the hoop stiffness of the cable conduit.

[0199] Combining Examples 1 with Examples 4-5, and the data in Tables 1 and 2, it can be seen that when the antioxidant in inner tube 1 is a mixture of antioxidant 1010 and antioxidant 168, with a weight ratio within the range of 1:(1.5-2), the cable conduit exhibits improved heat aging resistance compared to when only one antioxidant is added. This is likely due to the fact that antioxidant 1010 is a hindered phenol antioxidant, and antioxidant 168 is a phosphite antioxidant. These two antioxidants have different antioxidant mechanisms and modes of action. When mixed within a weight ratio of 1:(1.5-2), a synergistic effect is achieved, resulting in inner tube 1 having improved oxidation resistance and maintaining good mechanical strength even after a long period of heat aging.

[0200] Combining Example 5 with Example 6 and the data in Table 1 and Table 2, it can be seen that when the surface of boron nitride is modified by hydroxylation, the impact strength and tensile strength of the cable conduit can be significantly improved. This may be because the boron nitride is first treated with acid and then immersed in a 3-glycidyl propoxytrimethoxysilane solution, so that a large number of hydroxyl reaction sites are connected to the surface of the boron nitride, which is conducive to the full reaction and grafting of boron nitride and the silane coupling agent, fully improving the interfacial compatibility of boron nitride, and thus enabling boron nitride to be fully dispersed in the system, and effectively improving the bonding strength between boron nitride and polyethylene, which is conducive to further improving the mechanical strength of the inner tube 1, so that the cable conduit has higher impact strength and tensile strength.

[0201] Combining Examples 6 and 7 with the data in Tables 1 and 2 shows that using PBO fibers to form the fiber-reinforced layer 2 can further improve the cable conduit's impact strength, tensile strength, and ring stiffness. This is likely due to the high number of aromatic rings and oxygen heterocycles in the PBO fiber molecular chain, which gives the PBO fiber itself very high stiffness and strength. Compared to glass fibers, this further improves the cable conduit's ring stiffness and strength.

[0202] Combined with the data in Examples 7-9 and Tables 1 and 2, it can be seen that with the increase of the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil, the ring stiffness of the cable conduit gradually increases, but the impact strength and tensile strength show a trend of first increasing and then decreasing. When the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is 4%, the comprehensive performance of the cable conduit reaches the best. This may be because with the increase of the mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil, the crosslinking points on the molecular chain segments of the vinyl-terminated fluorosilicone oil increase, which in turn promotes further crosslinking of the vinyl-terminated fluorosilicone oil, and the crosslinking density of the protective layer 3 increases. Therefore, the hardness and strength of the protective layer 3 are both improved. At this time, the impact strength and tensile strength of the cable conduit show an upward trend. However, as the mass fraction of active hydrogen continues to increase, the crosslinking density of the protective layer 3 continues to increase, and it shows a hard and brittle characteristic, which leads to a decrease in the strength of the protective layer 3, causing the impact strength and tensile strength of the cable conduit to show a downward trend.

[0203] Combining Examples 8 and 10-11 with the data in Tables 1 and 2, it can be seen that when the outer layer filler is a mixture of fumed silica, ferric oxide, and zirconium silicate, and the weight ratio of fumed silica, ferric oxide, and zirconium silicate is within the range of 1:(0.2-0.4):(0.1-0.15), the surface wear resistance, ring stiffness, and heat aging resistance of the cable conduit are improved, resulting in better overall performance. This is likely due to the excellent high-temperature resistance of ferric oxide, which effectively improves the heat resistance of protective layer 3, helping to delay aging of protective layer 3 in hot environments and improve the heat aging resistance of the cable conduit. Secondly, zirconium silicate has high hardness and exhibits excellent wear resistance. Adding a small amount of zirconium silicate can effectively reduce the wear loss of protective layer 3, thereby improving the surface wear resistance of the cable conduit.

[0204] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A high-strength PE pipe, characterized by: From the inside to the outside, the inner tube (1), the fiber reinforcement layer (2), and the protective layer (3) are sequentially provided, wherein the inner tube (1) is made of high-density polyethylene extrusion, the fiber reinforcement layer (2) is formed by surface-modified fibers being woven and wrapped around the outer surface of the inner tube (1), and the protective layer (3) is formed by coating the outer surface of the fiber reinforcement layer (2) with an outer layer protective liquid and fully cross-linking and curing; The surface modified fiber is selected from any one of modified glass fiber or modified PBO fiber; The outer layer protective liquid comprises the following raw materials in parts by weight: Vinyl-terminated fluorosilicone oil: 25-30 parts; Hydrogen fluorinated silicone oil: 0.6-1.2 parts; Platinum catalyst: 0.08-0.13 parts; Outer layer filler: 12-18 parts; Wherein, the vinyl mass fraction of the vinyl-terminated fluorosilicone oil is 1.2%-1.5%, and the active hydrogen mass fraction of the hydrogen-containing fluorosilicone oil is 0.2%-0.6%; The outer layer filler is a mixture of fumed silica, ferric oxide and zirconium silicate, and is subjected to silane coupling treatment. The weight ratio of the fumed silica, the ferric oxide and the zirconium silicate is 1: (0.2-0.4): (0.1-0.15). The silane coupling treatment of the outer layer filler includes the following steps: D1. Add KH560 silane coupling agent to a certain concentration of ethanol solution, then heat to 40-50°C and continue to react for 60-90 minutes. Finally, slowly add the outer layer filler, maintain the temperature and continue stirring to react for 30-60 minutes, and filter to obtain the silane-coupled outer layer filler.

2. The high-strength PE pipe according to claim 1, characterized in that: The mass fraction of active hydrogen in the hydrogen-containing fluorosilicone oil is 0.2%-0.4%.

3. The high-strength PE pipe according to claim 1, characterized in that: The surface-modified fiber is modified glass fiber, and the modification of the modified glass fiber includes the following steps: Ca1. First, fully soak and clean the glass fiber with anhydrous ethanol. After drying, fully immerse the glass fiber in a mixed acid solution, heat and continuously stir the reaction for 30-40 minutes, then take it out, and then soak and clean it with distilled water several times until the cleaning solution is neutral. After drying, obtain the acid-etched glass fiber; Ca2. Soak the acid-etched glass fiber obtained in step Ca1 in KH570 silane coupling agent, heat and continuously stir to react for 15-20 minutes, then take it out and dry it to obtain the modified glass fiber.

4. The high-strength PE pipe according to claim 1, characterized in that: The surface-modified fiber is a modified PBO fiber, and the modification of the modified PBO fiber comprises the following steps: Cb1. First, the PBO fiber is thoroughly soaked and cleaned with anhydrous ethanol. After drying, the PBO fiber is fully immersed in a mixed solution of polyphosphoric acid / acetic acid at a certain concentration. The mixture is stirred for 2-6 minutes and then taken out. The PBO fiber is then soaked and cleaned multiple times with a weak base and distilled water until the cleaning solution becomes neutral. After drying, the acid-etched PBO fiber is obtained. Cb2. Immerse the acid-etched PBO fiber obtained in step Cb1 in heptafluorodecyltrichlorosilane, heat to 40-50° C., and continue stirring for 10-20 minutes before taking it out and drying it to obtain the modified PBO fiber.

5. The high-strength PE pipe according to claim 1, characterized in that: The inner tube (1) comprises the following raw materials in parts by weight: High-density polyethylene: 80-100 parts; Silane crosslinker: 1.2-2 parts; Peroxide initiator: 0.06-0.12 parts; Catalyst: 0.1-0.2 parts; Antioxidant: 0.4-0.6 parts; Stearic acid: 2-4 parts; Boron nitride: 8-12 parts; Silane coupling agent: 2-4 parts; The silane crosslinking agent includes any one of vinyltrimethoxysilane and vinyltriethoxysilane; the peroxide initiator includes any one of dibenzoyl peroxide and dicumyl peroxide.

6. The high-strength PE pipe according to claim 5, characterized in that: The antioxidant is prepared by mixing the antioxidant 1010 and the antioxidant 168 in a certain proportion, and the weight ratio of the antioxidant 1010 to the antioxidant 168 is 1:(1.5-2).

7. The high-strength PE pipe according to claim 5, characterized in that: The boron nitride is subjected to a hydroxylation treatment before being added and mixed, and the hydroxylation treatment comprises the following steps: B1. First, soak the boron nitride in an acidic solution, heat it to 70-85°C, fully stir and react for 5-8 hours, filter to obtain a filter residue, and then repeatedly soak and filter the filter residue with water until the filtrate is neutral. The final filtered residue is acid-treated boron nitride; B2. Soak the acid-treated boron nitride obtained in step B1 in a 3-glycidyl propoxytrimethoxysilane solution, heat to 80-110° C., fully stir and soak for 4-6 hours, take out and dry to obtain hydroxylated modified boron nitride.

8. A method for preparing a high-strength PE pipe, characterized in that: The method for preparing a high-strength PE pipe according to any one of claims 1 to 7 comprises the following steps: S1. First, high-density polyethylene is divided into AI material and BI material in a ratio of (9-9.5): (0.5-1), a silane crosslinker and a peroxide initiator are added to the AI ​​material, and the mixture is fully mixed to obtain AII material, a catalyst, stearic acid and an antioxidant are added to the BI material, and the mixture is fully mixed to obtain BII material, and the AII material and BII material are respectively granulated by melt extrusion to obtain AIII material and BIII material; S2, fully mixing the AIII material, the BIII material, the silane coupling agent and the boron nitride, and then forming the inner tube (1) semi-finished product by extrusion; S3, fumigating the semi-finished inner tube (1) obtained in step S2 with water vapor for 18-24 hours, taking it out, and then drying it to obtain the inner tube (1); S4, using surface-modified PBO fibers to weave and wrap around the surface of the inner tube (1) to form a fiber reinforcement layer (2) of a certain thickness; S5. Fully mix the vinyl-terminated fluorosilicone oil, hydrogen-containing fluorosilicone oil, platinum catalyst and outer filler to obtain an outer protective liquid. Fully apply the outer protective liquid to the surface of the fiber reinforcement layer (2). During the coating, the inner tube (1) is continuously rotated around the central axis, and then the rotation is maintained at 50-60° C. for 2-4 hours to form a protective layer (3) with a smooth surface, thereby obtaining a cable conduit.

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