High-strength steel skeleton plastic double-layer composite pipe and preparation method thereof

Abstract

The application relates to the technical field of composite pipes, in particular to a high-strength steel skeleton plastic double-layer composite pipe and a preparation method thereof. The application specifically comprises the following steps: step one: graphene oxide, titanium dioxide and silicon powder are modified and treated, and are grafted onto maleic anhydride grafted polyethylene to obtain reinforced resin; step two: (1) fluorine rubber is prepared; (2) the fluorine rubber, oxidized polyethylene wax and epoxy modifier are uniformly mixed, extruded and granulated to obtain modified rubber; step three: the steel skeleton is placed in a composite pipe forming mold, and is injected with organic resin liquid, and is cooled to obtain the high-strength steel skeleton plastic double-layer composite pipe. The organic resin liquid comprises the following components in parts by weight: 60-80 parts of ultrahigh molecular weight polyethylene resin, 5-10 parts of low-density polyethylene resin, 5-20 parts of reinforced resin, 5-10 parts of modified rubber, 4-6 parts of lubricant and 1-2 parts of antioxidant.

Description

Technical Field

[0001] This invention relates to the field of composite pipe technology, specifically to a high-strength steel-reinforced plastic double-layer composite pipe and its preparation method. Background Technology

[0002] Steel-reinforced plastic composite pipes are integral units composed of a reinforcing steel wire mesh skeleton and inner and outer layers of polyethylene plastic. The combination of rigidity and flexibility between the steel skeleton and the resin results in strong pressure resistance. Due to their excellent pressure resistance and corrosion resistance, steel-reinforced plastic composite pipes are widely used in municipal engineering, marine engineering, farmland irrigation, chemical industry, oil fields, gas fields, and other fields.

[0003] However, existing steel-reinforced plastic composite pipes on the market only have a polyethylene plastic outer layer, which is insufficient in strength. Furthermore, their poor wear resistance makes them prone to severe wear, significantly reducing their strength and greatly affecting their service life. Additionally, long-term use of these pipes leads to steel corrosion, which also negatively impacts their strength. Prolonged wear and corrosion cause a rapid decline in the pressure-bearing capacity of the steel-reinforced plastic composite pipe, rendering the pipeline system unusable and resulting in substantial economic losses.

[0004] In conclusion, it is essential and of great significance to develop a steel-reinforced plastic composite pipe with high strength, excellent wear resistance, and corrosion resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength steel-reinforced plastic double-layer composite pipe and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A high-strength steel-reinforced plastic double-layer composite pipe includes an organic layer and a steel reinforcement layer; the organic layer is obtained by injection molding and cooling of organic resin liquid;

[0008] The organic resin liquid comprises the following components, by weight: 60-80 parts of ultra-high molecular weight polyethylene resin, 5-10 parts of low-density polyethylene resin, 5-20 parts of reinforced resin, 5-10 parts of modified rubber, 4-6 parts of lubricant, and 1-2 parts of antioxidant.

[0009] Furthermore, the preparation method of the high-strength steel-reinforced plastic double-layer composite pipe includes the following steps:

[0010] Step 1: (1) Amination treatment of graphene oxide to obtain ammoniated graphene; (2) Modification of titanium dioxide and silicon micro powder with amino silane coupling agent to obtain modified filler; (3) Grafting of ammoniated graphene, modified filler and maleic anhydride onto polyethylene to obtain reinforced resin.

[0011] Step 2: (1) Initiate polymerization of tetrafluoroethylene, perfluoropropylene and perfluorobutene, and vulcanize to obtain fluororubber; (2) Mix fluororubber, oxidized polyethylene wax and epoxy modifier evenly, and extrude and granulate through a twin-screw extruder at 180-200℃ and 100-150rpm to obtain modified rubber.

[0012] Step 3: (1) Mix ultra-high molecular weight polyethylene resin, low density polyethylene resin, reinforced resin, modified rubber, lubricant and antioxidant evenly, heat to 170-200℃ to melt it, and obtain organic resin liquid; (2) Place the steel skeleton in the composite pipe forming mold, then inject the organic resin liquid into the mold, cool it, and obtain a high-strength steel skeleton plastic double-layer composite pipe.

[0013] Further, the specific process of step one is as follows: (1) Under microwave power of 100-120W, graphene oxide is heated at low temperature for 10-30s to complete microwave treatment, and then placed in a 20-28wt% ammonia solution. After ultrasonic dispersion treatment at 80-90℃ for 4-8h, the reaction solution is allowed to cool naturally to room temperature, filtered, washed, and dried to obtain ammoniated graphene; (2) Titanium dioxide and silicon micropowder are added to anhydrous ethanol at a mass ratio of 1:1, ultrasonically dispersed for 5-15min, and then... Add amino-based silane coupling agent, and mechanically stir at 50-70℃ for 2-6 hours. After filtration, washing and drying, the modified filler is obtained. (3) Add ammoniated graphene and modified filler to tetrahydrofuran, and ultrasonically disperse for 5-15 minutes. Then add maleic anhydride-grafted polyethylene and react at 30-80℃ for 2-12 hours. After the reaction is completed, add 0.1-2 mol / L sodium hydroxide ethanol solution to the reaction solution until the pH of the reaction solution is 7-9. After separation and washing, the reinforced resin is obtained.

[0014] Furthermore, the amino-based silane coupling agent includes, but is not limited to, one or more combinations of 3-aminopropyltriethoxysilane, (3-aminopropyl)trimethoxysilane, and anilinemethyltriethoxysilane, and is added in an amount of 5 to 10% of the total mass of titanium dioxide and silica powder.

[0015] Furthermore, the mass ratio of the ammoniated graphene, modified filler, and maleic anhydride-grafted polyethylene is (0.1-0.5):(0.1-0.5):1.

[0016] Graphene is a material that can enhance the corrosion resistance and wear resistance of polyethylene resin, but its dispersion in the resin is poor and it is prone to agglomeration. On the other hand, the solution introduces a hybrid filler of titanium dioxide and silica powder. The two fillers can improve the crystallization ability of polyethylene resin, synergistically enhancing the corrosion resistance and wear resistance of the resin, and further improving the mechanical properties of polyethylene resin. Furthermore, graphene, titanium dioxide, and silica powder are all thermally conductive materials. When polyethylene resin is in the molten state, they can increase the viscosity, thereby increasing the entanglement of polyethylene molecular chains, giving it a more complex network chain structure, and further enhancing the wear resistance, corrosion resistance, and strength of polyethylene resin. Therefore, in this scheme, after ammonifying graphene oxide and modifying the fillers (titanium dioxide and silicon micropowder) with an amino silane coupling agent, they are reacted with maleic anhydride-grafted polyethylene to form a stable chemical bond through amide groups. This enhances the dispersibility of the three components in the resin, and ultimately modifies the organic layer of the composite pipe to prepare a steel-reinforced plastic double-layer composite pipe with high strength, high wear resistance, and high corrosion resistance. Due to its good wear resistance and corrosion resistance, the composite pipe can maintain high strength for a long time, thus extending its service life.

[0017] Further, the preparation method of the fluororubber is as follows: (1) After adding deionized water into the reaction vessel, vacuum it to a vacuum degree of 0.02-0.1 MPa, then add emulsifier, tetrafluoroethylene, perfluoropropylene, and perfluorobutene until the pressure of the reaction vessel becomes 2-5 MPa, and obtain the reaction solution; (2) Heat the reaction solution to 60-130℃, then add initiator, chain transfer agent A, and pH adjuster, and stir the reaction; (3) During the reaction, continuously add tetrafluoroethylene, perfluoropropylene, and perfluorobutene to the reaction vessel to maintain constant pressure in the reaction vessel. After the reaction lasts for 2-6 hours, add chain transfer agent B to the reaction vessel. After the addition is completed, continue the reaction for 2-6 hours, and end the reaction to obtain the fluororubber polymer; (4) Mix the fluororubber polymer, modified carbon black, and zinc oxide evenly, then add sulfur, and vulcanize at 100-150℃ to obtain fluororubber.

[0018] Furthermore, the mass ratio of the tetrafluoroethylene, perfluoropropylene, and perfluorobutene is 1:75:100.

[0019] Furthermore, the emulsifier is ammonium perfluorooctanoate, and the amount added is 1 to 2% of the mass of deionized water.

[0020] Furthermore, the initiator is persulfate, and the amount added is 1-2% of the mass of deionized water.

[0021] Furthermore, the chain transfer agent A includes, but is not limited to, any one of carbon tetrachloride, acetone, diethyl malonate, and ethyl acetate, and is added in an amount of 1 to 2% of the mass of deionized water.

[0022] Furthermore, the chain transfer agent B is tetrafluorodibromoethane, and the amount added is 1-3% of the mass of deionized water.

[0023] Furthermore, the pH adjuster is borax, and the amount added is 0.5-1% of the mass of deionized water.

[0024] Furthermore, the mass ratio of the fluoropolymer, modified carbon black, zinc oxide, and sulfur is 10:(1-3):(0.3-0.6):(0.1-0.3).

[0025] Furthermore, the modified carbon black is prepared by adding carbon black, anhydrous ethanol, and vinyltrimethoxysilane into a stirrer, heating to 40-60°C, and stirring for 1-3 hours to obtain modified carbon black; wherein the amount of vinyltrimethoxysilane added is 2-5% of the mass of carbon black.

[0026] Furthermore, the mass ratio of the fluororubber, oxidized polyethylene wax, and epoxy modifier is 80:(4-8):(1-3).

[0027] Furthermore, the epoxy modifier includes, but is not limited to, any one of m-chloroperoxybenzoic acid, peracetic acid, and butanediperoxyic acid.

[0028] Furthermore, the screw ratio of the twin-screw extruder is 40:1.

[0029] Fluoropolymers are obtained by initiating polymerization with tetrafluoroethylene, perfluoropropylene, and perfluorobutene, followed by vulcanization to prepare fluororubber. Finally, the fluororubber is modified with oxidized polyethylene wax and an epoxy modifier to obtain modified rubber. Fluororubber has low surface energy, which reduces the friction coefficient of the organic layer in the composite pipe, and excellent corrosion resistance, significantly improving the wear and corrosion resistance of the composite pipe. However, its toughness is relatively poor. Therefore, this scheme modifies it sequentially with carbon black, oxidized polyethylene wax, and an epoxy modifier. Carbon black significantly improves the mechanical properties of fluororubber, enhancing its strength and toughness, thereby promoting the performance improvement of the organic layer. Oxidized polyethylene wax modification enhances its compatibility with the main resin. Finally, the epoxy modifier introduces polar epoxy groups by epoxidizing some double bonds in the fluororubber, enhancing intermolecular interactions and further improving the mechanical properties of the fluororubber. In short, this scheme prepares highly wear- and corrosion-resistant fluororubber and improves its mechanical properties, which enhances the mechanical properties and corrosion and wear resistance of the organic layer of the composite pipe, and enables it to maintain high strength of the composite pipe over a long period.

[0030] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) By combining ultra-high molecular weight polyethylene resin and low density polyethylene resin, the fluidity of the organic resin liquid can be enhanced, which is more conducive to injection molding; (2) Graphene, titanium dioxide and silicon micro powder work together to modify and graft maleic anhydride grafted polyethylene, which improves the dispersion of the three in the organic resin liquid, and greatly improves the wear resistance, corrosion resistance and strength of the composite pipe; (3) By modifying the composite pipe with fluororubber, the wear resistance, corrosion resistance and strength of the composite pipe are further enhanced; (4) Due to the synergistic effect of the reinforcing resin and the modified rubber, the wear resistance and corrosion resistance of the composite pipe are greatly improved, so that the composite pipe has a longer service life and can maintain a high strength for a long time. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In this embodiment, it should be noted that there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: graphene oxide, monolayer, thickness 0.55-1.2 nm, sheet diameter 0.5-3 μm, item number: G139803, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; titanium dioxide, purity 99%, particle size 5-10 nm, purchased from (Klamar) Shanghai Puzhen Biotechnology Co., Ltd.; silicon micropowder, mesh size 3000, item number: 33, purchased from Jiangxi Hengshengtai New Material Co., Ltd.; 3-aminopropyltriethoxysilane, purity 99%, purchased from Hubei Jusheng Technology Co., Ltd.; maleic anhydride grafted polyethylene, grafting rate 0.8-1, model: PE-12L. L, purchased from Hangzhou Jinwei Nanomaterials Co., Ltd.; tetrafluoroethylene, perfluoropropylene, and perfluorobutene, all with a purity of 99%, purchased from Shanghai Biyang Industrial Co., Ltd.; ammonium perfluorooctanoate, ammonium persulfate, carbon tetrachloride, borax, vinyltrimethoxysilane, and zinc oxide, all with a purity of 99%, purchased from Shanghai Jinjinle Industrial Co., Ltd.; tetrafluorodibromoethane and m-chloroperoxybenzoic acid, both with a purity of 99%, purchased from Jinjinle (Hunan) Chemical Co., Ltd.; carbon black with a purity of 99% and a particle size of 5-10 nm, and oxidized polyethylene wax with a purity of 99%, purchased from Hubei Yongkuo Technology Co., Ltd.; ultra-high molecular weight polyethylene resin, grade U050, with a molecular weight of 5 million, a particle size of 125 μm, and a density of 0.92-0.96 g / cm³. 2 Purchased from Dongguan Taotao Plastic Raw Materials Co., Ltd.; Low-density polyethylene resin, type: 2420K, molecular weight 50,000, density 0.924 g / cm³. 3Purchased from Dongguan Suyu Chemical Co., Ltd.; 99% pure butyl stearate purchased from Wuhan Penglei Biotechnology Co., Ltd.; Antioxidant model: 245, CAS No.: 36443-68-2, purchased from Tianjin Lianlong New Material Co., Ltd.

[0033] Example 1: A method for preparing a high-strength steel-reinforced plastic double-layer composite pipe:

[0034] Step 1: (1) Under microwave power of 100W, 10 parts of graphene oxide were heated at low temperature for 20s to complete the microwave treatment. Then, it was placed in 40 parts of 25wt% ammonia solution and ultrasonically dispersed at 85℃ for 6h. After the reaction solution was allowed to cool naturally to room temperature, it was filtered, washed, and dried to obtain ammoniated graphene. (2) 5 parts of titanium dioxide and 5 parts of silicon powder were added to 50 parts of anhydrous ethanol and ultrasonically dispersed for 10min. Then, 0.8 parts of 3-aminopropyl were added. Triethoxysilane was mechanically stirred at 60°C for 5 hours, and then filtered, washed and dried to obtain modified filler; (3) 9 parts of ammoniated graphene and 9 parts of modified filler were added to 180 parts of tetrahydrofuran, ultrasonically dispersed for 10 minutes, and then 30 parts of maleic anhydride-grafted polyethylene were added to it. The reaction was carried out at 50°C for 6 hours. After the reaction was completed, 1 mol / L sodium hydroxide ethanol solution was added dropwise to the reaction solution until the pH of the reaction solution reached 8. After separation and washing, the reinforced resin was obtained.

[0035] Step 2: 1. Tetrafluoroethylene, perfluoropropylene, and perfluorobutene are mixed in a mass ratio of 1:75:100 to obtain a mixture;

[0036] 2. (1) Add 100 parts of deionized water to the reaction vessel and evacuate it to a vacuum of 0.02 MPa. Then add 2 parts of ammonium perfluorooctanoate and the mixture until the pressure of the reaction vessel becomes 3 MPa to obtain the reaction solution. (2) Heat the reaction solution to 80°C and add 2 parts of ammonium persulfate, 2 parts of carbon tetrachloride and 1 part of borax. Stir the reaction. (3) During the reaction, continuously add the mixture to the reaction vessel to maintain the constant pressure of the reaction vessel. After the reaction has been going on for 5 hours, add 2 parts of tetrafluorodibromoethane to the reaction vessel. After the addition is complete, continue the reaction for 5 hours to end the reaction and obtain the fluoropolymer.

[0037] 3. Add 5 parts carbon black, 20 parts anhydrous ethanol, and 0.2 parts vinyltrimethoxysilane to a stirrer, heat to 50°C, and stir for 3 hours to obtain modified carbon black;

[0038] 4. Mix 25 parts of fluoropolymer, 5 parts of modified carbon black, and 1.5 parts of zinc oxide evenly, then add 0.5 parts of sulfur and vulcanize at 130°C to obtain fluororubber;

[0039] 5. Mix 25 parts of fluororubber, 1.8 parts of oxidized polyethylene wax and 0.6 parts of perfluoroacetic acid evenly, and extrude and granulate the mixture through a twin-screw extruder at 190°C and 120 rpm with a screw ratio of 40:1 to obtain modified rubber.

[0040] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 6 parts of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0041] (2) Place the steel skeleton in the composite pipe forming mold, then inject the organic resin liquid into the mold and cool it to obtain a high-strength steel skeleton plastic double-layer composite pipe.

[0042] Example 2: A method for preparing a high-strength steel-reinforced plastic double-layer composite pipe:

[0043] Step 1: (1) Under microwave power of 100W, 10 parts of graphene oxide were heated at low temperature for 20s to complete the microwave treatment. Then, it was placed in 40 parts of 25wt% ammonia solution and ultrasonically dispersed at 85℃ for 6h. After the reaction solution was allowed to cool naturally to room temperature, it was filtered, washed, and dried to obtain ammoniated graphene. (2) 5 parts of titanium dioxide and 5 parts of silicon powder were added to 50 parts of anhydrous ethanol and ultrasonically dispersed for 10min. Then, 0.8 parts of 3-aminopropyl were added. Triethoxysilane was mechanically stirred at 60°C for 5 hours, and then filtered, washed and dried to obtain modified filler; (3) 3 parts of ammoniated graphene and 3 parts of modified filler were added to 180 parts of tetrahydrofuran, ultrasonically dispersed for 10 minutes, and then 30 parts of maleic anhydride-grafted polyethylene were added to it. The reaction was carried out at 50°C for 6 hours. After the reaction was completed, 1 mol / L sodium hydroxide ethanol solution was added dropwise to the reaction solution until the pH of the reaction solution reached 8. After separation and washing, the reinforced resin was obtained.

[0044] Step 2: 1. Tetrafluoroethylene, perfluoropropylene, and perfluorobutene are mixed in a mass ratio of 1:75:100 to obtain a mixture;

[0045] 2. (1) Add 100 parts of deionized water to the reaction vessel and evacuate it to a vacuum of 0.02 MPa. Then add 2 parts of ammonium perfluorooctanoate and the mixture until the pressure of the reaction vessel becomes 2 MPa to obtain the reaction solution. (2) Heat the reaction solution to 80°C and add 2 parts of ammonium persulfate, 2 parts of carbon tetrachloride and 1 part of borax. Stir the reaction. (3) During the reaction, continuously add the mixture to the reaction vessel to maintain the constant pressure of the reaction vessel. After 5 hours of reaction, add 2 parts of tetrafluorodibromoethane to the reaction vessel. After the addition is complete, continue the reaction for 5 hours to end the reaction and obtain the fluoroolefin polymer.

[0046] 3. Add 5 parts carbon black, 20 parts anhydrous ethanol, and 0.2 parts vinyltrimethoxysilane to a stirrer, heat to 50°C, and stir for 3 hours to obtain modified carbon black;

[0047] 4. Mix 25 parts of fluoropolymer, 2.5 parts of modified carbon black, and 1.5 parts of zinc oxide evenly, then add 0.5 parts of sulfur and vulcanize at 130°C to obtain fluororubber;

[0048] 5. Mix 25 parts of fluororubber, 1.25 parts of oxidized polyethylene wax and 0.41 parts of perfluoroacetic acid evenly, and extrude and granulate the mixture through a twin-screw extruder at 190°C and 120 rpm with a screw ratio of 40:1 to obtain modified rubber.

[0049] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 6 parts of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0050] (2) Place the steel skeleton in the composite pipe forming mold, then inject the organic resin liquid into the mold and cool it to obtain a high-strength steel skeleton plastic double-layer composite pipe.

[0051] Example 3: A method for preparing a high-strength steel-reinforced plastic double-layer composite pipe:

[0052] Step 1: (1) Under microwave power of 100W, 10 parts of graphene oxide were heated at low temperature for 20s to complete the microwave treatment. Then, it was placed in 40 parts of 25wt% ammonia solution and ultrasonically dispersed at 85℃ for 6h. After the reaction solution was allowed to cool naturally to room temperature, it was filtered, washed, and dried to obtain ammoniated graphene. (2) 5 parts of titanium dioxide and 5 parts of silicon powder were added to 50 parts of anhydrous ethanol and ultrasonically dispersed for 10min. Then, 0.8 parts of 3-aminopropyltriazine were added. Ethoxysilane was mechanically stirred at 60°C for 5 hours, and then filtered, washed and dried to obtain modified filler; (3) 15 parts of ammoniated graphene and 15 parts of modified filler were added to 180 parts of tetrahydrofuran, ultrasonically dispersed for 10 minutes, and then 30 parts of maleic anhydride-grafted polyethylene were added to it. The reaction was carried out at 50°C for 6 hours. After the reaction was completed, 1 mol / L sodium hydroxide ethanol solution was added dropwise to the reaction solution until the pH of the reaction solution reached 8. After separation and washing, the reinforced resin was obtained.

[0053] Step 2: 1. Tetrafluoroethylene, perfluoropropylene, and perfluorobutene are mixed in a mass ratio of 1:75:100 to obtain a mixture;

[0054] 2. (1) Add 100 parts of deionized water to the reaction vessel and evacuate it to a vacuum of 0.02 MPa. Then add 2 parts of ammonium perfluorooctanoate and the mixture until the pressure of the reaction vessel becomes 5 MPa to obtain the reaction solution. (2) Heat the reaction solution to 80°C and add 2 parts of ammonium persulfate, 2 parts of carbon tetrachloride and 1 part of borax. Stir the reaction. (3) During the reaction, continuously add the mixture to the reaction vessel to maintain the constant pressure of the reaction vessel. After 5 hours of reaction, add 2 parts of tetrafluorodibromoethane to the reaction vessel. After the addition is complete, continue the reaction for 5 hours to end the reaction and obtain the fluoroolefin polymer.

[0055] 3. Add 5 parts carbon black, 20 parts anhydrous ethanol, and 0.2 parts vinyltrimethoxysilane to a stirrer, heat to 50°C, and stir for 3 hours to obtain modified carbon black;

[0056] 4. Mix 25 parts of fluoropolymer, 2.5 parts of modified carbon black, and 1.5 parts of zinc oxide evenly, then add 0.5 parts of sulfur and vulcanize at 130°C to obtain fluororubber;

[0057] 5. Mix 25 parts of fluororubber, 5 parts of oxidized polyethylene wax and 1.67 parts of perfluoroacetic acid evenly, and extrude and granulate the mixture through a twin-screw extruder at 190°C and 120 rpm with a screw ratio of 40:1 to obtain modified rubber.

[0058] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 6 parts of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0059] (2) Place the steel skeleton in the composite pipe forming mold, then inject the organic resin liquid into the mold and cool it to obtain a high-strength steel skeleton plastic double-layer composite pipe.

[0060] Comparative Example 1: Compared with Example 1, the proportion of organic resin liquid was adjusted in Comparative Example 1, while the rest of the process remained unchanged; specifically:

[0061] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 1 part of reinforcing resin, 6 parts of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0062] Comparative Example 2: Compared with Example 1, Comparative Example 2 adjusted the proportion of the organic resin liquid, while keeping the other processes unchanged; specifically:

[0063] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 1 part of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0064] Comparative Example 3: Compared with Example 1, Comparative Example 3 was modified by not adding reinforcing resin, while keeping the rest of the process unchanged; specifically:

[0065] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 6 parts of modified rubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0066] Comparative Example 4: Compared with Example 1, Comparative Example 4 was modified by not adding modified rubber, while keeping the rest of the process unchanged; specifically:

[0067] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0068] Comparative Example 5: Compared with Example 1, Comparative Example 5 adjusted the following: In step two, the fluororubber was not modified with oxidized polyethylene wax and perfluoroacetic acid; other processes remained unchanged, specifically:

[0069] Step 3: (1) Mix 70 parts of ultra-high molecular weight polyethylene resin, 8 parts of low density polyethylene resin, 17 parts of reinforcing resin, 6 parts of fluororubber, 5 parts of butyl stearate and 2 parts of antioxidant evenly, heat to 190°C to melt it, and obtain an organic resin solution.

[0070] Performance testing: The high-strength steel-reinforced plastic double-layer composite pipes prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to strength performance testing. The specific testing methods are as follows:

[0071] (1) Perform bending performance tests according to the test methods in GB / T 9341-2008;

[0072] (2) According to the test methods in GB / T 6111-2018 and GB / T 15560-1995, the compressive strength and burst strength were tested using a pressure-resistant bursting machine;

[0073] (3) The composite pipe was subjected to acid treatment (at 25°C, acid etching of its interior with 30wt% sulfuric acid solution for 72h) and alkaline treatment (at 25°C, alkaline etching of its interior with 30wt% sodium hydroxide solution for 72h), and the strength tests in (1) and (2) were performed again.

[0074] The specific test results are shown in Table 1:

[0075] Table 1

[0076]

[0077] Results Analysis: As can be seen from the data in Table 1, the high-strength steel-reinforced plastic double-layer composite pipe prepared by this invention has high strength. Compared with the comparative examples, the reinforcing resin and modified rubber have a significant impact on the strength of the composite pipe. In addition, the high-strength steel-reinforced plastic double-layer composite pipe prepared by this invention has excellent corrosion resistance and can still maintain high strength after corrosion. It can better meet actual needs and reduce economic losses caused by corrosion of the composite pipe, resulting in strength reduction and leakage.

[0078] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength steel-reinforced plastic double-layer composite pipe, characterized in that: Includes the following steps: Step 1: (1) Ammoniated graphene oxide is treated to obtain ammoniated graphene; (2) Titanium dioxide and silicon micro powder are modified with amino silane coupling agents to obtain modified fillers; (3) Ammoniated graphene and modified fillers are reacted with maleic anhydride-grafted polyethylene to obtain reinforced resin. Step 2: (1) Initiate polymerization of tetrafluoroethylene, perfluoropropylene and perfluorobutene, and vulcanize to obtain fluororubber; (2) Mix fluororubber, oxidized polyethylene wax and epoxy modifier evenly, and extrude and granulate through a twin-screw extruder at 180-200℃ and 100-150rpm to obtain modified rubber. Step 3: (1) Mix ultra-high molecular weight polyethylene resin, low density polyethylene resin, reinforcing resin, modified rubber, lubricant and antioxidant evenly, heat to 170-200℃ to melt it, and obtain organic resin liquid; (2) Place the steel skeleton in the composite pipe forming mold, then inject the organic resin liquid into the mold, cool it, and obtain a high-strength steel skeleton plastic double-layer composite pipe. The specific process of step one is as follows: (1) Graphene oxide is heated at a microwave power of 100-120W for 10-30s, and then placed in a 20-28wt% ammonia solution. After ultrasonic dispersion at 80-90℃ for 4-8h, the reaction solution is allowed to cool naturally to room temperature. After filtration, washing and drying, ammoniated graphene is obtained. (2) Add titanium dioxide and silicon micro powder to anhydrous ethanol at a mass ratio of 1:1, disperse ultrasonically for 5 to 15 minutes, add amino silane coupling agent, and mechanically stir at 50 to 70°C for 2 to 6 hours. After filtration, washing and drying, the modified filler is obtained. (3) Add ammoniated graphene and modified filler to tetrahydrofuran, disperse ultrasonically for 5-15 min, then add maleic anhydride-grafted polyethylene, react at 30-80℃ for 2-12 h, after the reaction is completed, add 0.1-2 mol / L sodium hydroxide ethanol solution dropwise to the reaction solution until the pH of the reaction solution is 7-9, and obtain the reinforced resin after separation and washing. The amino-based silane coupling agent includes one or more combinations of 3-aminopropyltriethoxysilane, (3-aminopropyl)trimethoxysilane, and anilinemethyltriethoxysilane, and is added in an amount of 5-10% of the total mass of titanium dioxide and silica powder; the mass ratio of the ammoniated graphene, modified filler, and maleic anhydride-grafted polyethylene is (0.1-0.5):(0.1-0.5):

1. The preparation method of the fluororubber is as follows: (1) After adding deionized water into the reaction vessel, evacuate it to a vacuum of 0.02-0.1 MPa, then add emulsifier, tetrafluoroethylene, perfluoropropylene, and perfluorobutene until the pressure of the reaction vessel becomes 2-5 MPa, and obtain the reaction solution. (2) Heat the reaction solution to 60-130°C, then add the initiator, chain transfer agent A, and pH adjuster, and stir to react; (3) During the reaction, tetrafluoroethylene, perfluoropropylene and perfluorobutene are continuously added to the reaction vessel to maintain constant pressure in the reaction vessel. After the reaction has been going on for 2 to 6 hours, chain transfer agent B is added to the reaction vessel. After the addition is complete, the reaction continues for 2 to 6 hours to end the reaction and obtain fluoropolymer. (4) Mix the fluoropolymer, modified carbon black and zinc oxide evenly, then add sulfur and vulcanize at 100-150°C to obtain fluororubber. The mass ratio of tetrafluoroethylene, perfluoropropylene, and perfluorobutene is 1:75:100; the emulsifier is ammonium perfluorooctanoate, added at 1-2% of the mass of deionized water; the initiator is persulfate, added at 1-2% of the mass of deionized water; the chain transfer agent A is carbon tetrachloride, added at 1-2% of the mass of deionized water; the chain transfer agent B is tetrafluorodibromoethane, added at 1-3% of the mass of deionized water; the pH adjuster is borax, added at 0.5-1% of the mass of deionized water; and the mass ratio of fluoropolymer, modified carbon black, zinc oxide, and sulfur is 10:(1-3):(0.3-0.6):(0.1-0.3). The mass ratio of the fluororubber, oxidized polyethylene wax, and epoxy modifier is 80:(4-8):(1-3); The epoxy modifier includes any one of m-chloroperoxybenzoic acid, peracetic acid, and butanediperoxyic acid; The organic resin liquid comprises the following components, by weight: 60-80 parts of ultra-high molecular weight polyethylene resin, 5-10 parts of low-density polyethylene resin, 5-20 parts of reinforced resin, 5-10 parts of modified rubber, 4-6 parts of lubricant, and 1-2 parts of antioxidant.

2. The method for preparing a high-strength steel-reinforced plastic double-layer composite pipe according to claim 1, characterized in that: The modified carbon black is prepared by adding carbon black, anhydrous ethanol, and vinyltrimethoxysilane into a stirrer, heating to 40-60°C, and stirring for 1-3 hours to obtain modified carbon black. The amount of vinyltrimethoxysilane added is 2-5% of the mass of carbon black.

3. A high-strength steel-reinforced plastic double-layer composite pipe, characterized in that: It is prepared by the method for preparing a high-strength steel-reinforced plastic double-layer composite pipe according to any one of claims 1 to 2.

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