Environment-friendly heat-conducting composite pipe and preparation method thereof

Abstract

The invention belongs to the field of pipes, and particularly relates to an environment-friendly heat-conducting composite pipe and a preparation method thereof. The environment-friendly heat-conducting composite pipe provided by the invention is prepared by carrying out three-layer co-extrusion on a pipe inner layer material, a pipe middle layer material and a pipe outer layer material and then carrying out electron beam radiation crosslinking, the inner layer material of the pipe comprises the following components: high-density polyethylene, a compound carbon material, a toughening agent, a compatibilizer, a nucleating agent, a dispersing agent, a lubricating agent, an antioxidant and a sensitizing agent; the middle layer material of the pipe comprises the following components: polylactic acid, polybutylene terephthalate adipate, a compound carbon material, a compatibilizer, a water repellent agent, a chain extender, an antioxidant and a sensitizer; and the outer layer material of the pipe comprises the following components: high-density polyethylene, a toughening agent, a compatibilizer, color master batch, a dispersing agent, a lubricating agent, an antioxidant and a sensitizing agent. The composite pipe provided by the invention has good thermal conductivity, heat resistance and environmental protection property.

Description

Technical Field

[0001] This invention belongs to the field of pipe materials, and particularly relates to an environmentally friendly thermally conductive composite pipe and its preparation method. Background Technology

[0002] Currently, polyethylene pipes are the primary type of thermally conductive tubing, but their thermal conductivity is relatively low, making the improvement of thermal conductivity a key research focus in this field. Traditional methods improve performance by adding thermally conductive fillers such as alumina, boron nitride, and graphite, but high addition amounts significantly reduce the mechanical properties and resistance to environmental stress cracking of the tubing. While highly efficient thermally conductive fillers such as graphene and carbon nanotubes can significantly improve thermal conductivity at low addition amounts, their high cost hinders large-scale application, thus necessitating the development of low-cost alternative fillers. Biomass graphene has become a research hotspot due to its low cost, renewability, and environmental friendliness; however, existing preparation methods require high-temperature pyrolysis (above 1600℃) combined with catalysts to promote graphitization, resulting in excessive energy consumption. A more economical preparation process needs to be explored. Furthermore, higher demands are being placed on the environmental friendliness, quality, and technical performance of tubing materials, but directly using biodegradable resins cannot meet long-term usage requirements. Therefore, how to achieve environmental upgrades while ensuring the performance of thermally conductive tubing has become a key issue that needs to be addressed. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide an environmentally friendly thermally conductive composite pipe and its preparation method. The composite pipe provided by this invention combines good thermal conductivity, heat resistance and environmental friendliness.

[0004] This invention provides an environmentally friendly thermally conductive composite pipe, which is made by three-layer co-extrusion of inner pipe material, middle pipe material and outer pipe material, followed by electron beam radiation cross-linking.

[0005] The inner layer material of the pipe comprises: high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant and sensitizer;

[0006] The components of the intermediate layer material of the pipe include: polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer;

[0007] The outer layer of the pipe material comprises: high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer;

[0008] The components of the composite carbon material include: bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifiers, and catalysts.

[0009] Preferably, the bamboo charcoal-based graphene oxide is obtained by calcining the solid reaction product obtained by reacting bamboo powder and sulfuric acid in the presence of a metal compound catalyst.

[0010] Preferably, the bamboo powder has a mesh size of 300-500.

[0011] And / or, the concentration of the sulfuric acid is 96-98 wt%;

[0012] And / or, the metal compound catalyst is one or more of nickel oxide, nickel nitrate, nickel chloride, cobalt nitrate, cobalt acetate, cobalt nitrate, ferric nitrate, and ferrous sulfate;

[0013] And / or, the mass ratio of the bamboo powder, sulfuric acid and metal compound catalyst is 100:(800-1000):(0.5-1).

[0014] Preferably, the carbon black in the composite carbon material has a DBP absorption value of 250–280 mL / 100 g and a specific surface area of ​​150–210 m². 2 / g, with an average particle size of 30-40nm;

[0015] And / or, the carbon nanotubes in the composite carbon material are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes;

[0016] And / or, the average particle size of the spherical micron carbon powder in the composite carbon material is 1 to 3 μm;

[0017] And / or, the surface modifier in the composite carbon material is one or more of diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, and pentaethylenehexamine;

[0018] And / or, the catalyst in the composite carbon material is one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole and N-hydroxysuccinimide.

[0019] Preferably, the density of the high-density polyethylene in the inner layer of the pipe is 0.94–0.96 g / cm³. 3 The melt index at 190℃ and 2.16kg is 3-6 g / 10min;

[0020] And / or, the toughening agent in the inner layer of the pipe is one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer;

[0021] And / or, the compatibilizer in the inner layer of the pipe is one or more of the following: polyethylene grafted with succinic anhydride, polyethylene grafted with citraconic anhydride, polyethylene grafted with itaconic anhydride, polyethylene grafted with octenoyl succinic anhydride, polyethylene grafted with maleic anhydride, polyethylene grafted with glycidyl methacrylate, polyethylene grafted with methyl ethylene acrylate, polyethylene grafted with methyl methacrylate, and polyethylene grafted with butyl methacrylate.

[0022] And / or, the nucleating agent in the inner layer of the pipe is one or more of the following: n-hexyl-substituted oxalamide, cyclohexyl-substituted oxalamide, poly(4-methoxy)-diphenoloxycarbonylphenol acrylate, poly(4-methoxy-4'-acryloyloxybenzoate), benzoimidazolinone, isoindoleone, dimethylbenzyl sorbitol, di(p-ethyldibenzyl)sorbitol, dichlorobenzyl sorbitol, and sodium benzoate;

[0023] And / or, the dispersant in the inner layer of the pipe is one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax;

[0024] And / or, the lubricant in the inner layer of the pipe is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate;

[0025] And / or, the antioxidant in the inner layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamate) pentaerythritol ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine;

[0026] And / or, the sensitizer in the inner layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0027] Preferably, the polylactic acid in the intermediate layer of the pipe has a number-average molecular weight of 200,000 to 300,000 and a melt index of 3 to 5 g / 10 min at 190°C and 2.16 kg.

[0028] And / or, the number-average molecular weight of polybutylene adipate in the intermediate layer of the pipe is 200,000 to 400,000, and the melt index is 4 to 6 g / 10 min at 190°C and 2.16 kg.

[0029] And / or, the compatibilizer in the intermediate layer of the pipe is one or more of the following: polylactic acid grafted with succinic anhydride, polylactic acid grafted with citraconic anhydride, polylactic acid grafted with itaconic anhydride, polylactic acid grafted with octenoyl succinic anhydride, polylactic acid grafted with maleic anhydride, polylactic acid grafted with glycidyl methacrylate, polylactic acid grafted with ethylene methyl acrylate, polylactic acid grafted with methyl methacrylate, and polylactic acid grafted with butyl methacrylate.

[0030] And / or, the water-resistant agent in the intermediate layer of the pipe is one or more of polycarbodiimide, monocarbodiimide and zirconium phosphate nanosheets;

[0031] And / or, the chain extender in the intermediate layer of the pipe is one or more of 2,4-toluene diisocyanate, pyromellitic anhydride, ethylene-glycidyl methacrylate copolymer, styrene-glycidyl methacrylate copolymer and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane;

[0032] And / or, the antioxidant in the intermediate layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine;

[0033] And / or, the sensitizer in the intermediate layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0034] Preferably, the density of the high-density polyethylene in the outer layer of the pipe is 0.94–0.96 g / cm³. 3 The melt index at 190℃ and 2.16kg is 3-6 g / 10min;

[0035] And / or, the toughening agent in the outer layer of the pipe is one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer;

[0036] And / or, the compatibilizer in the outer layer of the pipe is one or more of the following: polyethylene grafted with succinic anhydride, polyethylene grafted with citraconic anhydride, polyethylene grafted with itaconic anhydride, polyethylene grafted with octenoyl succinic anhydride, polyethylene grafted with maleic anhydride, polyethylene grafted with glycidyl methacrylate, polyethylene grafted with methyl ethylene acrylate, polyethylene grafted with methyl methacrylate, and polyethylene grafted with butyl methacrylate.

[0037] And / or, the color of the masterbatch in the outer layer of the pipe is one or more of the following: black, purple, orange-red, orange-yellow, bright red, pink, pink, rose red, gray, silver-gray, dark gray, white, grass green, dark green, sky blue, brown, gold, and coffee.

[0038] And / or, the dispersant in the outer layer of the pipe is one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax;

[0039] And / or, the lubricant in the outer layer of the pipe is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate;

[0040] And / or, the antioxidant in the outer layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine;

[0041] And / or, the sensitizer in the outer layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0042] Preferably, the mass ratio of high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant and sensitizer in the inner layer material of the pipe is 100:(5~15):(10~20):(2~4):(0.5~2):(0.5~1):(0.5~2):(0.1~1):(0.5~2);

[0043] And / or, the mass ratio of polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer in the intermediate layer material of the pipe is 100:(40~60):(5~15):(2~4):(0.5~2):(0.2~0.5):(0.1~1):(0.5~2);

[0044] And / or, the mass ratio of high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer in the outer layer material of the pipe is 100:(10~20):(2~4):(0.5~1):(0.5~1):(0.5~2):(0.1~1):(0.5~2);

[0045] And / or, the mass ratio of bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifier and catalyst in the composite carbon material is 100:(20-30):(2-4):(10-20):(150-250):(1-2).

[0046] This invention provides a method for preparing the environmentally friendly thermally conductive composite pipe described in the above technical solution, comprising the following steps:

[0047] The inner layer material, the middle layer material, and the outer layer material of the pipe are added to the hopper of the three-layer co-extrusion pipe extruder for three-layer co-extrusion to obtain a three-layer co-extruded pipe.

[0048] The three-layer co-extruded pipe is cross-linked by electron beam radiation to obtain an environmentally friendly thermally conductive composite pipe.

[0049] Preferably, the irradiation dose of the electron beam radiation crosslinking is 80–140 kGy.

[0050] Compared with existing technologies, this invention provides an environmentally friendly thermally conductive composite pipe and its preparation method. The environmentally friendly thermally conductive composite pipe provided by this invention is manufactured by co-extruding three layers—an inner layer, a middle layer, and an outer layer—followed by electron beam radiation crosslinking. The inner layer comprises high-density polyethylene, a compounded carbon material, a toughening agent, a compatibilizer, a nucleating agent, a dispersant, a lubricant, an antioxidant, and a sensitizer. The middle layer comprises polylactic acid, polybutylene adipate terephthalate, a compounded carbon material, a compatibilizer, a water-resistant agent, a chain extender, an antioxidant, and a sensitizer. The outer layer comprises high-density polyethylene, a toughening agent, a compatibilizer, a color masterbatch, a dispersant, a lubricant, an antioxidant, and a sensitizer. The compounded carbon material comprises bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron-sized carbon powder, a surface modifier, and a catalyst. This invention uses bamboo charcoal-based graphene oxide as the thermally conductive filler in composite pipes, and combines it with carbon materials of different dimensions to form a more complete thermally conductive network, significantly improving the thermal conductivity of the composite pipes. Moreover, the bamboo charcoal-based graphene oxide used can be prepared by reacting bamboo powder and sulfuric acid at room temperature in the presence of a metal compound catalyst, followed by low-temperature calcination. The preparation process does not require a high-temperature pyrolysis step, resulting in low energy consumption. Furthermore, the use of polylactic acid as the intermediate layer base material improves the biodegradability of the composite pipes. Additionally, by using a grafted compatibilizer to promote the entanglement of molecules between layers during multilayer co-extrusion, and by utilizing radiation crosslinking to initiate crosslinking of interfacial molecules, the compatibility and bonding strength of each layer are synergistically promoted, ultimately resulting in an environmentally friendly thermally conductive pipe with excellent overall performance. Detailed Implementation

[0051] 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.

[0052] This invention provides an environmentally friendly thermally conductive composite pipe, which is made by three-layer co-extrusion of inner pipe material, middle pipe material and outer pipe material, followed by electron beam radiation cross-linking.

[0053] The inner layer material of the pipe comprises: high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant and sensitizer;

[0054] The components of the intermediate layer material of the pipe include: polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer;

[0055] The outer layer of the pipe material comprises: high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer;

[0056] The components of the composite carbon material include: bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifiers, and catalysts.

[0057] In the composite pipe provided by the present invention, the bamboo charcoal-based graphene oxide in the composite carbon material is preferably obtained by calcining the solid reaction product obtained by reacting bamboo powder and sulfuric acid in the presence of a metal compound catalyst. The bamboo powder is preferably 300-500 mesh, specifically 300 mesh, 320 mesh, 350 mesh, 370 mesh, 400 mesh, 420 mesh, 450 mesh, 470 mesh, or 500 mesh; the sulfuric acid concentration is preferably 96-98 wt%, specifically 96 wt%, 96.5 wt%, 97 wt%, 97.5 wt%, or 98 wt%; the metal compound catalyst is preferably one or more of nickel oxide, nickel nitrate, nickel chloride, cobalt nitrate, cobalt acetate, cobalt nitrate, ferric nitrate, and ferrous sulfate, wherein the nickel oxide is preferably nano-nickel oxide; the mass ratio of bamboo powder, sulfuric acid, and metal compound catalyst is preferably 100:(800-1000):(0.5-1), and the mass ratio of bamboo powder to sulfuric acid is specifically 100:800, 100:850, 100:900, or 100:800. The mass ratio of bamboo powder to metal compound catalyst can be 950 or 100:1000, specifically 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, or 100:1; the reaction system is not heated during the reaction; the reaction time is preferably 4-6 hours, specifically 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours; the calcination method is preferably vacuum calcination; the calcination temperature is preferably 300-400℃, specifically 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃; the calcination time is preferably 20-40 minutes, specifically 20 minutes, 25 minutes, 30 minutes, 35 minutes, or 40 minutes.

[0058] In the composite pipe provided by this invention, the DBP absorption value (dibutyl phthalate absorption value) of the carbon black in the composite carbon material is preferably 250-280 mL / 100g, specifically 250 mL / 100g, 255 mL / 100g, 260 mL / 100g, 265 mL / 100g, 270 mL / 100g, 275 mL / 100g, or 280 mL / 100g; the specific surface area of ​​the carbon black is preferably 150-210 m² / g. 2 / g, specifically 150m2 / g、155m 2 / g、160m 2 / g、165m 2 / g、170m 2 / g、175m 2 / g、180m 2 / g、185m 2 / g、190m 2 / g、195m 2 / g、200m 2 / g、205m 2 / g or 210m 2 / g; the average particle size of the carbon black is preferably 30-40nm, specifically 30nm, 31nm, 32nm, 33nm, 34nm, 35nm, 36nm, 37nm, 38nm, 39nm or 40nm.

[0059] In the composite pipe provided by the present invention, the mass ratio of carbon black to bamboo charcoal-based graphene oxide in the composite carbon material is preferably (20-30):100, specifically 20:100, 21:100, 22:100, 23:100, 24:100, 25:100, 26:100, 27:100, 28:100, 29:100 or 30:100.

[0060] In the composite tube provided by this invention, the carbon nanotubes in the composite carbon material are preferably one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled (three or more wall layers) carbon nanotubes; the outer diameter of the single-walled carbon nanotubes is preferably 1-2 nm, specifically 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, or 2 nm; the outer diameter of the double-walled carbon nanotubes is preferably 2-4 nm, specifically 2 nm, 2.2 nm, 2.5 nm, 2.7 nm, 2.9 nm, 3 nm, 3.2 nm, 3.5 nm, 3.7 nm, or 4 nm; the outer diameter of the multi-walled carbon nanotubes is preferably 8-10 nm, specifically 8 nm, 8.2 nm, 8.5 nm, 8.7 nm, 8.9 nm, 9 nm, 9.2 nm, 9.5 nm, 9.7 nm, or 10 nm.

[0061] In the composite pipe provided by the present invention, the mass ratio of the carbon nanotubes to bamboo charcoal-based graphene oxide in the composite carbon material is preferably (2-4):100, specifically 2:100, 2.3:100, 2.5:100, 2.7:100, 3:100, 3.2:100, 3.5:100, 3.7:100 or 4:100.

[0062] In the composite pipe provided by the present invention, the average particle size of the spherical micron carbon powder in the composite carbon material is preferably 1 to 3 μm, specifically 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, 2.3 μm, 2.5 μm, 2.7 μm or 3 μm.

[0063] In the composite pipe provided by the present invention, the mass ratio of the spherical micron carbon powder to bamboo charcoal-based graphene oxide in the composite carbon material is preferably (10-20):100, specifically 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100 or 20:100.

[0064] In the composite pipe provided by the present invention, the surface modifier in the composite carbon material is preferably one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0065] In the composite pipe provided by the present invention, the mass ratio of the surface modifier to bamboo charcoal-based graphene oxide in the composite carbon material is preferably (150-250):100, specifically 150:100, 160:100, 170:100, 180:100, 190:100, 200:100, 210:100, 220:100, 230:100, 240:100 or 250:100.

[0066] In the composite pipe provided by the present invention, the catalyst in the composite carbon material is preferably one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole and N-hydroxysuccinimide.

[0067] In the composite pipe provided by the present invention, the mass ratio of the catalyst to bamboo charcoal-based graphene oxide in the composite carbon material is preferably (1-2):100, specifically 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0068] In the composite pipe provided by the present invention, the composite carbon material is preferably prepared by mixing and reacting the bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifier and catalyst in a solvent, and then by solid-liquid separation, washing and drying. The solvent is preferably one or more of methanol, ethanol, and dimethylformamide; the mass ratio of the solvent to bamboo charcoal-based graphene oxide is preferably (500-600):100, specifically 500:100, 510:100, 520:100, 530:100, 540:100, 550:100, 560:100, 570:100, 580:100, 590:100, or 600:100; the mixing reaction temperature is preferably 30-50℃, specifically 30℃, 35℃, 40℃, 45℃, or 50℃; the mixing reaction time is preferably 4-6 hours, specifically 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours; the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃, or 80℃.

[0069] In the composite pipe provided by this invention, the density of the high-density polyethylene in the inner layer material is preferably 0.94–0.96 g / cm³. 3 Specifically, it can be 0.94 g / cm³. 3 0.942 g / cm 3 0.945g / cm 3 0.947 g / cm 3 0.95g / cm 3 0.952g / cm 3 0.955g / cm 3 0.957g / cm 3 Or 0.96g / cm 3 The melt index of the high-density polyethylene at 190℃ and 2.16kg is preferably 3 to 6 g / 10min, specifically 3 g / 10min, 3.2 g / 10min, 3.5 g / 10min, 3.7 g / 10min, 4 g / 10min, 4.2 g / 10min, 4.5 g / 10min, 4.7 g / 10min, 5 g / 10min, 5.2 g / 10min, 5.5 g / 10min, 5.7 g / 10min or 6 g / 10min.

[0070] In the composite pipe provided by the present invention, the mass ratio of high-density polyethylene to composite carbon material in the inner layer of the pipe is preferably 100:(5-15), specifically 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14 or 100:15.

[0071] In the composite pipe provided by this invention, the toughening agent in the inner layer material is preferably one or more of linear low-density polyethylene, high-density polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer. The density of the linear low-density polyethylene is preferably 0.91–0.93 g / cm³. 3 Specifically, it can be 0.91 g / cm³. 3 0.915g / cm 3 0.92g / cm 3 0.925g / cm 3 Or 0.93g / cm 3 The linear low-density polyethylene (LDPE) preferably has a melt index of 3–5 g / 10 min at 190°C and 2.16 kg, specifically 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, or 5 g / 10 min; the high-density polyethylene (HDPE) preferably has a density of 0.91–0.925 g / cm³. 3 Specifically, it can be 0.91 g / cm³. 3 0.915g / cm 3 0.92g / cm 3 Or 0.925g / cm 3 The melt flow index of the high-pressure polyethylene at 190℃ and 2.16 kg is preferably 3-5 g / 10 min, specifically 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, or 5 g / 10 min; the density of the metallocene medium-density polyethylene is preferably 0.925-0.935 g / cm³. 3 Specifically, it can be 0.925 g / cm³. 3 0.93g / cm 3 Or 0.935g / cm 3 The melt index of the metallocene medium-density polyethylene at 190°C and 2.16 kg is preferably 4–6 g / 10 min, specifically 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, or 6 g / 10 min; the density of the ethylene-octene random copolymer is preferably 0.89–0.92 g / cm³. 3 Specifically, it can be 0.89 g / cm³. 3 0.9g / cm 3 0.91g / cm 3 or 0.92g / cm 3The melt index of the ethylene-octene random copolymer at 190°C and 2.16 kg is preferably 4 to 6 g / 10 min, specifically 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min or 6 g / 10 min.

[0072] In the composite pipe provided by the present invention, the mass ratio of the toughening agent to high-density polyethylene in the inner layer material of the pipe is preferably (10-20):100, specifically 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100 or 20:100.

[0073] In the composite pipe provided by the present invention, the compatibilizer in the inner layer material is preferably a polyethylene graft, more preferably one or more of polyethylene grafted with succinic anhydride, polyethylene grafted with citraconic anhydride, polyethylene grafted with itaconic anhydride, polyethylene grafted with octenoyl succinic anhydride, polyethylene grafted with maleic anhydride, polyethylene grafted with glycidyl methacrylate, polyethylene grafted with methyl ethylene acrylate, polyethylene grafted with methyl methacrylate, and polyethylene grafted with butyl methacrylate; the grafting degree of the polyethylene graft is preferably 1-3%, specifically 1%, 1.2%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7%, or 3%. The melt index of the polyethylene graft at 190°C and 2.16 kg is preferably 2 to 4 g / 10 min, specifically 2 g / 10 min, 2.2 g / 10 min, 2.5 g / 10 min, 2.7 g / 10 min, 3 g / 10 min, 3.2 g / 10 min, 3.5 g / 10 min, 3.7 g / 10 min, or 4 g / 10 min.

[0074] In the composite pipe provided by the present invention, the mass ratio of the compatibilizer to high-density polyethylene in the inner layer material of the pipe is preferably (2-4):100, specifically 2:100, 2.3:100, 2.5:100, 2.7:100, 3:100, 3.2:100, 3.5:100, 3.7:100 or 4:100.

[0075] In the composite pipe provided by the present invention, the nucleating agent in the inner layer material of the pipe is preferably one or more of the following: n-hexyl-substituted oxalamide, cyclohexyl-substituted oxalamide, poly(4-methoxy)-diphenoloxycarbonylphenol acrylate, poly(4-methoxy-4'-acryloyloxybenzoic acid phenyl ester), benzoimidazolinone, isoindoline, dimethylbenzyl sorbitol, di(p-ethyldibenzyl)sorbitol, dichlorobenzyl sorbitol, and sodium benzoate.

[0076] In the composite pipe provided by the present invention, the mass ratio of the nucleating agent to high-density polyethylene in the inner layer material of the pipe is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0077] In the composite pipe provided by the present invention, the dispersant in the inner layer material of the pipe is preferably one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax.

[0078] In the composite pipe provided by the present invention, the mass ratio of the dispersant to high-density polyethylene in the inner layer material of the pipe is preferably (0.5-1):100, specifically 0.5:100, 0.55:100, 0.6:100, 0.65:100, 0.7:100, 0.75:100, 0.8:100, 0.85:100, 0.9:100, 0.95:100 or 1:100.

[0079] In the composite pipe provided by the present invention, the lubricant in the inner layer of the pipe is preferably one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate.

[0080] In the composite pipe provided by the present invention, the mass ratio of the lubricant to high-density polyethylene in the inner layer material of the pipe is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0081] In the composite pipe provided by the present invention, the antioxidant in the inner layer material is preferably one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamate) pentaerythritol ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine.

[0082] In the composite pipe provided by the present invention, the mass ratio of the antioxidant to high-density polyethylene in the inner layer material of the pipe is preferably (0.1-1):100, specifically 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100.

[0083] In the composite pipe provided by the present invention, the sensitizer in the inner layer material of the pipe is preferably one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

[0084] In the composite pipe provided by the present invention, the mass ratio of the sensitizer to high-density polyethylene in the inner layer material of the pipe is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0085] In the composite pipe provided by this invention, the inner layer material is preferably obtained by melt blending and extruding the high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant, and sensitizer in an extruder, followed by granulation and drying. The melt blending temperature is preferably 170–190°C, specifically 170°C, 175°C, 180°C, 185°C, or 190°C; the extrusion temperature is preferably 160–180°C, specifically 160°C, 165°C, 170°C, 175°C, or 180°C; and the drying temperature is preferably 60–80°C, specifically 60°C, 65°C, 70°C, 75°C, or 80°C.

[0086] In the composite pipe provided by the present invention, the number average molecular weight of the polylactic acid in the intermediate layer material is preferably 200,000 to 300,000, specifically 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000 or 300,000; the melt index of the polylactic acid at 190°C and 2.16 kg is preferably 3 to 5 g / 10 min, specifically 3 g / 10 min, 3.2 g / 10 min, 3.5 g / 10 min, 3.7 g / 10 min, 4 g / 10 min, 4.2 g / 10 min, 4.5 g / 10 min, 4.7 g / 10 min or 5 g / 10 min.

[0087] In the composite pipe provided by this invention, the number-average molecular weight of the polybutylene adipate in the intermediate layer is preferably 200,000 to 400,000, specifically 200,000, 230,000, 250,000, 270,000, 300,000, 320,000, 350,000, 370,000, or 400,000; the melt index of the polybutylene adipate at 190°C and 2.16 kg is preferably 4 to 6 g / 10 min, specifically 4 g / 10 min. n, 4.2g / 10min, 4.5g / 10min, 4.7g / 10min, 5g / 10min, 5.2g / 10min, 5.5g / 10min, 5.7g / 10min or 6g / 10min; the molar ratio of the aliphatic polyester (BA) repeating unit to the aromatic polyester (BT) repeating unit of the polybutylene terephthalate is preferably (60:40) to (40:60).

[0088] In the composite pipe provided by the present invention, the mass ratio of polybutylene adipate to polylactic acid in the intermediate layer of the pipe is preferably (40-60):100, specifically 40:100, 41:100, 42:100, 43:100, 44:100, 45:100, 46:100, 47:100, 48:100, 49:100, 50:100, 51:100, 52:100, 53:100, 54:100, 55:100, 56:100, 57:100, 58:100, 59:100 or 60:100.

[0089] In the composite pipe provided by the present invention, the compatibilizer in the intermediate layer of the pipe is preferably a polylactic acid graft, more preferably one or more of polylactic acid grafted with succinic anhydride, polylactic acid grafted with citrate anhydride, polylactic acid grafted with itaconic anhydride, polylactic acid grafted with octenoyl succinic anhydride, polylactic acid grafted with maleic anhydride, polylactic acid grafted with glycidyl methacrylate, polylactic acid grafted with methyl methacrylate, polylactic acid grafted with methyl methacrylate, and polylactic acid grafted with butyl methacrylate; the grafting degree of the polylactic acid graft is preferably 1-3%, specifically... The content is 1%, 1.2%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7%, or 3%; the melt index of the polylactic acid graft at 190°C and 2.16 kg is preferably 2-4 g / 10 min, specifically 2 g / 10 min, 2.2 g / 10 min, 2.5 g / 10 min, 2.7 g / 10 min, 3 g / 10 min, 3.2 g / 10 min, 3.5 g / 10 min, 3.7 g / 10 min, or 4 g / 10 min.

[0090] In the composite pipe provided by the present invention, the mass ratio of the compatibilizer to polylactic acid in the intermediate layer of the pipe is preferably (2-4):100, specifically 2:100, 2.3:100, 2.5:100, 2.7:100, 3:100, 3.2:100, 3.5:100, 3.7:100 or 4:100.

[0091] In the composite pipe provided by the present invention, the water-resistant agent in the intermediate layer of the pipe is preferably one or more of polycarbodiimide, monocarbodiimide, and zirconium phosphate nanosheets; the number average molecular weight of the polycarbodiimide is preferably 8000-10000, specifically 8000, 8250, 8500, 8750, 9000, 9250, 9500, 9750, or 10000; the thickness of the zirconium phosphate nanosheets is preferably 1-2 nm, specifically 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, or 2 nm.

[0092] In the composite pipe provided by the present invention, the mass ratio of the water-resistant agent to polylactic acid in the intermediate layer material is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0093] In the composite pipe provided by the present invention, the chain extender in the intermediate layer of the pipe is preferably one or more of 2,4-toluene diisocyanate, pyromellitic anhydride, ethylene-glycidyl methacrylate copolymer, styrene-glycidyl methacrylate copolymer, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0094] In the composite pipe provided by the present invention, the mass ratio of the chain extender to polylactic acid in the intermediate layer material of the pipe is preferably (0.2-0.5):100, specifically 0.2:100, 0.25:100, 0.3:100, 0.35:100, 0.4:100, 0.45:100 or 0.5:100.

[0095] In the composite pipe provided by the present invention, the antioxidant in the intermediate layer of the pipe is preferably one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine.

[0096] In the composite pipe provided by the present invention, the mass ratio of the antioxidant to polylactic acid in the intermediate layer of the pipe is preferably (0.1-1):100, specifically 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100.

[0097] In the composite pipe provided by the present invention, the sensitizer in the intermediate layer of the pipe is preferably one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

[0098] In the composite pipe provided by the present invention, the mass ratio of the sensitizer to polylactic acid in the intermediate layer material is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0099] In the composite pipe provided by this invention, the intermediate layer material is preferably obtained by melt blending and extruding polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant, and sensitizer in an extruder, followed by granulation and drying. The melt blending temperature is preferably 180–190°C, specifically 180°C, 182°C, 185°C, 187°C, or 190°C; the extrusion temperature is preferably 170–180°C, specifically 170°C, 172°C, 175°C, 178°C, or 180°C; and the drying temperature is preferably 60–80°C, specifically 60°C, 65°C, 70°C, 75°C, or 80°C.

[0100] In the composite pipe provided by this invention, the density of the high-density polyethylene in the outer layer is preferably 0.94–0.96 g / cm³. 3 Specifically, it can be 0.94 g / cm³. 3 0.942 g / cm 3 0.945g / cm 3 0.947 g / cm 3 0.95g / cm 3 0.952g / cm 3 0.955g / cm 3 0.957g / cm 3 Or 0.96g / cm 3The melt index of the high-density polyethylene at 190℃ and 2.16kg is preferably 3 to 6 g / 10min, specifically 3 g / 10min, 3.2 g / 10min, 3.5 g / 10min, 3.7 g / 10min, 4 g / 10min, 4.2 g / 10min, 4.5 g / 10min, 4.7 g / 10min, 5 g / 10min, 5.2 g / 10min, 5.5 g / 10min, 5.7 g / 10min or 6 g / 10min.

[0101] In the composite pipe provided by this invention, the toughening agent in the outer layer of the pipe is preferably one or more of linear low-density polyethylene, high-density polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer. The density of the linear low-density polyethylene is preferably 0.91–0.93 g / cm³. 3 Specifically, it can be 0.91 g / cm³. 3 0.915g / cm 3 0.92g / cm 3 0.925g / cm 3 Or 0.93g / cm 3 The linear low-density polyethylene (LDPE) preferably has a melt index of 3–5 g / 10 min at 190°C and 2.16 kg, specifically 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, or 5 g / 10 min; the high-density polyethylene (HDPE) preferably has a density of 0.91–0.925 g / cm³. 3 Specifically, it can be 0.91 g / cm³. 3 0.915g / cm 3 0.92g / cm 3 Or 0.925g / cm 3 The melt flow index of the high-pressure polyethylene at 190℃ and 2.16 kg is preferably 3-5 g / 10 min, specifically 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, or 5 g / 10 min; the density of the metallocene medium-density polyethylene is preferably 0.925-0.935 g / cm³. 3 Specifically, it can be 0.925 g / cm³. 3 0.93g / cm 3 Or 0.935g / cm 3The melt index of the metallocene medium-density polyethylene at 190°C and 2.16 kg is preferably 4–6 g / 10 min, specifically 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, or 6 g / 10 min; the density of the ethylene-octene random copolymer is preferably 0.89–0.92 g / cm³. 3 Specifically, it can be 0.89 g / cm³. 3 0.9g / cm 3 0.91g / cm 3 or 0.92g / cm 3 The melt index of the ethylene-octene random copolymer at 190°C and 2.16 kg is preferably 4 to 6 g / 10 min, specifically 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min or 6 g / 10 min.

[0102] In the composite pipe provided by the present invention, the mass ratio of the toughening agent to high-density polyethylene in the outer layer of the pipe is preferably (10-20):100, specifically 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100 or 20:100.

[0103] In the composite pipe provided by this invention, the compatibilizer in the outer layer of the pipe is preferably a polyethylene graft, more preferably one or more of polyethylene grafted succinic anhydride, polyethylene grafted citrate anhydride, polyethylene grafted itaconic anhydride, polyethylene grafted octenoyl succinic anhydride, polyethylene grafted maleic anhydride, polyethylene grafted glycidyl methacrylate, polyethylene grafted methyl methacrylate, polyethylene grafted methyl methacrylate, and polyethylene grafted butyl methacrylate; the grafting degree of the polyethylene graft is preferably 1-3%, specifically... 1%, 1.2%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7%, or 3%; the melt index of the polyethylene graft at 190°C and 2.16 kg is preferably 2-4 g / 10 min, specifically 2 g / 10 min, 2.2 g / 10 min, 2.5 g / 10 min, 2.7 g / 10 min, 3 g / 10 min, 3.2 g / 10 min, 3.5 g / 10 min, 3.7 g / 10 min, or 4 g / 10 min.

[0104] In the composite pipe provided by the present invention, the mass ratio of the compatibilizer to high-density polyethylene in the outer layer of the pipe is preferably (2-4):100, specifically 2:100, 2.3:100, 2.5:100, 2.7:100, 3:100, 3.2:100, 3.5:100, 3.7:100 or 4:100.

[0105] In the composite pipe provided by the present invention, the color masterbatch in the outer layer of the pipe is preferably an environmentally friendly color masterbatch; the color of the color masterbatch is preferably one or more of the following: black, purple, orange-red, orange-yellow, bright red, pink, rose red, gray, silver-gray, dark gray, white, grass green, dark green, sky blue, brown, gold, and coffee.

[0106] In the composite pipe provided by the present invention, the mass ratio of the color masterbatch to high-density polyethylene in the outer layer material of the pipe is preferably (0.5-1):100, specifically 0.5:100, 0.55:100, 0.6:100, 0.65:100, 0.7:100, 0.75:100, 0.8:100, 0.85:100, 0.9:100, 0.95:100 or 1:100.

[0107] In the composite pipe provided by the present invention, the dispersant in the outer layer of the pipe is preferably one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax.

[0108] In the composite pipe provided by the present invention, the mass ratio of the dispersant to high-density polyethylene in the outer layer of the pipe is preferably (0.5-1):100, specifically 0.5:100, 0.55:100, 0.6:100, 0.65:100, 0.7:100, 0.75:100, 0.8:100, 0.85:100, 0.9:100, 0.95:100 or 1:100.

[0109] In the composite pipe provided by the present invention, the lubricant in the outer layer of the pipe is preferably one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate.

[0110] In the composite pipe provided by the present invention, the mass ratio of the lubricant to high-density polyethylene in the outer layer of the pipe is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0111] In the composite pipe provided by the present invention, the antioxidant in the outer layer of the pipe is preferably one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine.

[0112] In the composite pipe provided by the present invention, the mass ratio of the antioxidant to high-density polyethylene in the outer layer of the pipe is preferably (0.1-1):100, specifically 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100.

[0113] In the composite pipe provided by the present invention, the sensitizer in the outer layer of the pipe is preferably one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0114] In the composite pipe provided by the present invention, the mass ratio of the sensitizer to high-density polyethylene in the outer layer of the pipe is preferably (0.5-2):100, specifically 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2:100.

[0115] In the composite pipe provided by this invention, the outer layer material is preferably obtained by melt blending and extruding the high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant, and sensitizer in an extruder, followed by granulation and drying. The melt blending temperature is preferably 170–190°C, specifically 170°C, 175°C, 180°C, 185°C, or 190°C; the extrusion temperature is preferably 160–180°C, specifically 160°C, 165°C, 170°C, 175°C, or 180°C; and the drying temperature is preferably 60–80°C, specifically 60°C, 65°C, 70°C, 75°C, or 80°C.

[0116] In the composite pipe provided by the present invention, the temperature of the three-layer co-extrusion is preferably 180-190℃, specifically 180℃, 182℃, 185℃, 187℃ or 190℃; the irradiation dose of the electron beam radiation crosslinking is preferably 80-140kGy, specifically 80kGy, 85kGy, 90kGy, 95kGy, 100kGy, 105kGy, 110kGy, 115kGy, 120kGy, 125kGy, 130kGy, 135kGy or 140kGy.

[0117] In the composite pipe provided by the present invention, the thickness of the inner layer of the pipe is preferably 1 to 1.5 mm, specifically 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm or 1.5 mm; the thickness of the middle layer of the pipe is preferably 0.6 to 1 mm, specifically 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm or 1 mm; the thickness of the outer layer of the pipe is preferably 0.4 to 0.5 mm, specifically 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm or 0.5 mm.

[0118] This invention also provides a method for preparing the environmentally friendly thermally conductive composite pipe described in the above technical solution, comprising the following steps:

[0119] The inner layer material, the middle layer material, and the outer layer material of the pipe are added to the hopper of the three-layer co-extrusion pipe extruder for three-layer co-extrusion to obtain a three-layer co-extruded pipe.

[0120] The three-layer co-extruded pipe is cross-linked by electron beam radiation to obtain an environmentally friendly thermally conductive composite pipe.

[0121] In the preparation method provided by this invention, the bamboo charcoal-based graphene oxide, the raw material for preparing the composite carbon material in the inner layer material and the middle layer material of the pipe, is preferably prepared according to the following steps:

[0122] Bamboo powder, catalyst, and sulfuric acid were mixed and reacted. After the reaction was completed, water was added to the reaction system to quench the reaction. The solid and liquid were separated, and the obtained solid reaction product was calcined to obtain bamboo charcoal-based graphene oxide.

[0123] In the above-mentioned bamboo charcoal-based graphene oxide preparation steps provided by the present invention, the relevant information and dosage ratio of each raw material have been introduced above and will not be repeated here.

[0124] In the above-mentioned bamboo charcoal-based graphene oxide preparation steps provided by the present invention, the reaction is preferably carried out under stirring conditions; the reaction system is not heated during the reaction; the reaction time is preferably 4-6 hours, specifically 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours; the amount of water added for the water-quenching reaction is preferably 40-50 times the mass of bamboo powder; the reaction system is preferably cooled during the water-quenching reaction to ensure that the temperature of the reaction system is maintained at 10-40°C, specifically 10°C, 15°C, 20°C, or 25°C (room temperature). The calcination temperature is preferably 300-400℃, specifically 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃ or 400℃; the calcination time is preferably 20-40 min, specifically 20 min, 25 min, 30 min, 35 min or 40 min.

[0125] In the preparation method provided by the present invention, the composite carbon materials in the inner layer material and the intermediate layer material of the pipe are preferably prepared according to the following steps:

[0126] Bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron-sized carbon powder, surface modifiers, and catalysts are mixed and reacted in a solvent. After solid-liquid separation, washing, and drying, a composite carbon material is obtained.

[0127] In the preparation steps of the composite carbon material provided by the present invention, the relevant information and dosage ratio of each raw material have been introduced above and will not be repeated here.

[0128] In the above-mentioned preparation steps of the composite carbon material provided by the present invention, the specific process of the mixing reaction preferably includes: first mixing bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder with a solvent, then mixing with a surface modifier and a catalyst, and then reacting under stirring conditions. The preferred method for mixing the bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron-sized carbon powder, and solvent is ultrasonic mixing, with the ultrasonic mixing time preferably being 20–40 min, specifically 20 min, 25 min, 30 min, 35 min, or 40 min; the preferred method for mixing with the surface modifier and catalyst is ultrasonic mixing, with the ultrasonic mixing time preferably being 20–40 min, specifically 20 min, 25 min, 30 min, 35 min, or 40 min; the preferred reaction temperature is 30–50 °C, specifically 30 °C, 35 °C, 40 °C, 45 °C, or 50 °C; and the preferred reaction time is 4–6 h, specifically 4 h, 4.5 h, 5 h, 5.5 h, or 6 h.

[0129] In the above-mentioned preparation steps of the composite carbon material provided by the present invention, the solid-liquid separation method is preferably vacuum filtration; the washing method is preferably multiple water washing; the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃ or 80℃.

[0130] In the preparation method provided by the present invention, the inner layer material of the pipe is preferably prepared according to the following steps:

[0131] High-density polyethylene, compound carbon materials, toughening agents, compatibilizers, nucleating agents, dispersants, lubricants, antioxidants, and sensitizers are added to an extruder for melt blending and extrusion, followed by extrusion granulation and drying to obtain the inner layer material of the pipe.

[0132] In the above-mentioned pipe inner layer material preparation steps provided by the present invention, the relevant information and dosage ratio of each raw material have been introduced above and will not be repeated here; each raw material is preferably premixed evenly before being added to the extruder; the extruder is preferably a twin-screw extruder; the screw speed of the extruder is preferably 150-200 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm; the melt blending temperature is preferably 170-190℃, specifically 170℃, 175℃, 180℃, 185℃ or 190℃; the extrusion temperature is preferably 160-180℃, specifically 160℃, 165℃, 170℃, 175℃ or 180℃; the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃ or 80℃.

[0133] In the preparation method provided by the present invention, the intermediate layer material of the pipe is preferably prepared according to the following steps:

[0134] Polylactic acid, polybutylene adipate terephthalate, compound carbon materials, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer are added to an extruder for melt blending and extrusion, extrusion granulation, and drying to obtain the intermediate layer material of the pipe.

[0135] In the above-mentioned pipe intermediate layer material preparation steps provided by the present invention, the relevant information and dosage ratio of each raw material have been introduced above and will not be repeated here; each raw material is preferably premixed evenly before being added to the extruder; the extruder is preferably a twin-screw extruder; the screw speed of the extruder is preferably 150-200 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm; the melt blending temperature is preferably 180-190℃, specifically 180℃, 182℃, 185℃, 187℃ or 190℃; the extrusion temperature is preferably 170-180℃, specifically 170℃, 172℃, 175℃, 178℃ or 180℃; the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃ or 80℃.

[0136] In the preparation method provided by the present invention, the outer layer material of the pipe is preferably prepared according to the following steps:

[0137] High-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer are added to an extruder for melt blending and extrusion, extrusion granulation, and drying to obtain the outer layer material of the pipe.

[0138] In the above-mentioned pipe outer layer material preparation steps provided by the present invention, the relevant information and dosage ratio of each raw material have been introduced above and will not be repeated here; each raw material is preferably premixed evenly before being added to the extruder; the extruder is preferably a twin-screw extruder; the screw speed of the extruder is preferably 150-200 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm; the melt blending temperature is preferably 170-190℃, specifically 170℃, 175℃, 180℃, 185℃ or 190℃; the extrusion temperature is preferably 160-180℃, specifically 160℃, 165℃, 170℃, 175℃ or 180℃; the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃ or 80℃.

[0139] In the preparation method provided by the present invention, the processing temperature of the three-layer co-extrusion pipe extruder is preferably 180-190℃, specifically 180℃, 182℃, 185℃, 187℃ or 190℃; the screw speed of the three-layer co-extrusion pipe extruder is preferably 100-150 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm.

[0140] In the preparation method provided by the present invention, the irradiation dose of the electron beam radiation crosslinking is preferably 80-140 kGy, specifically 80 kGy, 85 kGy, 90 kGy, 95 kGy, 100 kGy, 105 kGy, 110 kGy, 115 kGy, 120 kGy, 125 kGy, 130 kGy, 135 kGy or 140 kGy.

[0141] The technical solution provided by this invention includes at least the following key points:

[0142] (1) The bamboo charcoal-based graphene oxide used can be prepared by reacting bamboo powder and sulfuric acid at room temperature in the presence of a metal compound catalyst and then calcining at low temperature. The preparation process does not require a high-temperature pyrolysis process and has low energy consumption.

[0143] (2) Bamboo charcoal-based graphene oxide is used as a thermally conductive filler, and thermally conductive carbon materials of different dimensions and particle sizes are selected to be compounded with it. Through the complementary effect of shape and size, a more perfect thermally conductive network is formed, which significantly improves the thermal conductivity of the composite pipe.

[0144] (3) Through multi-layer co-extrusion technology, while ensuring usability, polylactic acid and other biodegradable resins are wrapped inside the pipe, reducing the amount of polyethylene used and giving the composite pipe environmental protection; at the same time, by modifying the filler, adding anti-hydrolysis agent and multi-layer sandwich structure, the degradability of polylactic acid and other biodegradable layers is reduced, and the service life is delayed.

[0145] (4) By using grafted compatibilizers to promote the entanglement of molecules between layers during melt extrusion, the compatibility and bonding strength of the biodegradable layer and the polyethylene layer are increased.

[0146] (5) Using irradiation crosslinking to induce crosslinking of interfacial molecules further promotes interlayer adhesion and the formation of thermal conductive network, and effectively improves the heat resistance of composite pipes.

[0147] The technical solution provided by this invention has at least the following advantages:

[0148] (1) This invention utilizes a catalyst and concentrated sulfuric acid to prepare bamboo charcoal-based graphene oxide, forms a complete thermally conductive network through carbon material compounding, integrates a biodegradable layer, and utilizes compatibilizers and radiation crosslinking to improve interlayer compatibility and bonding strength, thereby achieving efficient preparation of biomass graphene oxide and environmentally friendly thermally conductive composite pipe.

[0149] (2) The environmentally friendly thermally conductive composite pipe provided by the present invention has high application value. The carbon materials of different dimensions, such as bamboo charcoal-based graphene, constitute a perfect thermal conduction path. The pipe has excellent comprehensive performance and can be applied to multiple fields.

[0150] (3) This invention prepares graphene oxide using concentrated sulfuric acid and a catalyst, achieving low-cost, large-scale preparation of bamboo charcoal-based graphene. The integration of a biodegradable layer through multilayer extrusion technology further enhances the environmental friendliness of the composite pipe. The process is relatively simple and the entire process is safe and environmentally friendly.

[0151] (4) The environmentally friendly thermally conductive composite pipe provided by the present invention has a simple preparation process, high production efficiency, and can be mass-produced.

[0152] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0153] In the following embodiments and comparative examples of the present invention, the melt index is the melt index under the conditions of 190°C and 2.16 kg.

[0154] In the following embodiments and comparative examples of the present invention, the specific methods for evaluating thermal conductivity and heat resistance are as follows:

[0155] (1) Thermal conductivity: The pipe was cut open and the curved surface of the pipe was pressed into a sheet at 175°C. The sheet was then made into a circular plate with a diameter of 3cm. According to ASTM D5470–2012 standard, the thermal conductivity of the material was tested at 25°C using a thermal conductivity meter. The final result was the average value of the data measured by five samples.

[0156] (2) Heat resistance: The pipe was cut open and the curved surface of the pipe was pressed into a sheet at 175°C. The sheet was then made into a square plate sample with a length and width of 1 cm. The Vicat softening temperature of the material was tested using a Vicat softening temperature tester. The final result was the average value of the data measured by the five samples.

[0157] (3) Tensile properties: The pipe was cut open and the curved surface of the pipe was pressed into a sheet at 175°C. Then it was cut into dumbbell-shaped specimens and tested with a universal tensile testing machine according to ASTM D638-2014. The tensile speed was 50 mm / min. Five sets of parallel measurements were taken and the average value of the five sets of data was taken.

[0158] (4) Performance retention rate: After the composite pipe is placed at 85℃ and 85RH% for 30 days, the tensile strength and elongation at break are retested, and the tensile strength retention rate and elongation at break retention rate are calculated.

[0159] (5) Degradation performance: The special material for the degradation layer was crushed into powder by a pulverizer and then tested by a soil compost degradation instrument according to GB / T 19277.1. The test time was 180 days, and three parallel tests were conducted. The average value of the three sets of data was taken.

[0160] Example 1

[0161] First, 100 parts by weight of 300-mesh bamboo powder and 0.5 parts by weight of nano-nickel oxide were placed in 800 parts by weight of 96 wt% concentrated sulfuric acid and stirred for 4 hours at a stirring speed of 400 rpm. After the reaction was completed, 4000 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 6 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to remove sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 20 minutes at a calcination temperature of 300℃. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0162] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 20 parts by weight of carbon black with an average particle size of 30 nm, a DBP absorption value of 250 mL / 100 g, and a specific surface area of ​​150 m². 2 2 parts by weight of single-walled carbon nanotubes with an outer diameter of 1.2 nm and 10 parts by weight of spherical micron carbon powder with an average particle size of 1 μm were placed in 600 parts by weight of methanol solvent and ultrasonically treated for 20 min. Then, 150 parts by weight of diethylenetriamine and 1 part by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine were added, and ultrasonic treatment was continued for another 20 min. After that, the mixture was stirred at 30 °C for 4 h and filtered with a vacuum filter. After washing with deionized water several times, the resulting solid was dried at 60 °C to obtain the composite carbon material.

[0163] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min and a density of 0.910 g / cm³ per 10 parts by weight. 3The following materials were used: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 5 parts by weight of the above-mentioned compounded carbon material, 2 parts by weight of polyethylene grafted with succinic anhydride with a melt index of 2 g / 10 min and a grafting degree of 1%, 0.5 parts by weight of n-hexyl-substituted oxalamide, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl bis-stearamide, 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 170°C, the extrusion temperature was set to 160°C, and the screw extrusion speed was 150 rpm. The composite material was then dried at 60°C to obtain the inner layer special material.

[0164] Take 100 parts by weight of polylactic acid with a melt index of 3.0 g / 10 min and a number-average molecular weight of 200,000, 40 parts by weight of polybutylene adipate terephthalate with a melt index of 4.0 g / 10 min and a number-average molecular weight of 200,000 (molar ratio BA:BT = 60:40), 5 parts by weight of the above-mentioned compound carbon material, 2 parts by weight of polylactic acid grafted with succinic anhydride with a melt index of 2 g / 10 min and a grafting degree of 1%, 0.5 parts by weight of polycarbodiimide with a number-average molecular weight of 8000, and 0.2 parts by weight of 2,4-toluene. Diisocyanate, 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 180°C, the extrusion temperature at 170°C, and the screw extrusion speed at 150 rpm. The composite material was then dried at 60°C to obtain a special material for the intermediate layer.

[0165] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min and a density of 0.910 g / cm³ per 10 parts by weight. 3The following materials were used: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 2 parts by weight of polyethylene grafted with succinic anhydride and a melt index of 2 g / 10 min with a grafting degree of 1%, 0.5 parts by weight of purple environmentally friendly masterbatch, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl distearate, 0.1 parts by weight of thiadiglycol di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 170℃, the extrusion temperature was set at 160℃, and the screw extrusion speed was 150 rpm. The composite material was then dried at 60℃ to obtain the outer layer special material.

[0166] The aforementioned special materials for each layer are placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature is set to 180℃, the screw extrusion speed is 100 rpm, the outer layer thickness is 0.4 mm, the middle layer thickness is 0.6 mm, and the inner layer thickness is 1.0 mm. The prepared pipe is then subjected to an irradiation crosslinking device with an irradiation dose of 80 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promotes the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improves the overall performance of the composite pipe, such as its heat resistance, ultimately obtaining an environmentally friendly thermally conductive composite pipe.

[0167] Tests showed that the degradation rate of the intermediate layer was 85.2%; the tensile strength of the composite pipe was 32.5 MPa, the tensile strength retention rate was 92.7%, the elongation at break was 508%, the break productivity retention rate was 91.8%, the thermal conductivity was 1.84 W / (m·K), and the Vicat softening temperature was 121.1℃.

[0168] Example 2

[0169] First, 100 parts by weight of 350-mesh bamboo powder and 0.6 parts by weight of nickel nitrate were placed in 850 parts by weight of 96.5 wt% concentrated sulfuric acid and stirred for 4.5 hours at a stirring speed of 450 rpm. After the reaction was completed, 4250 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 6.5 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to remove sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 25 minutes at a calcination temperature of 325°C. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0170] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 22 parts by weight of carbon black with an average particle size of 32 nm, a DBP absorption value of 258 mL / 100 g, and a specific surface area of ​​165 m². 2 2.5 parts by weight of multi-walled carbon nanotubes with an outer diameter of 8.0 nm and 13 parts by weight of spherical micron carbon powder with an average particle size of 1.5 μm were placed in 650 parts by weight of anhydrous ethanol solvent and ultrasonically treated for 25 min. Then, 175 parts by weight of triethylenetetramine and 1.2 parts by weight of triethylenetetramine were added, and ultrasonic treatment was continued for another 25 min. After that, the mixture was stirred at 35 °C for 4.5 h, filtered with a vacuum filter, washed multiple times with deionized water, and the resulting solid was dried at 65 °C to obtain the composite carbon material.

[0171] Take 100 parts by weight with a density of 0.945 g / cm³ 3 The high-density polyethylene has a melt flow index of 3.8 g / 10 min and a density of 0.915 g / cm³ per 12 parts by weight. 3 The following materials were used: high-pressure polyethylene with a melt index of 3.5 g / 10 min, 8 parts by weight of the above-mentioned compound carbon material, 2.5 parts by weight of polyethylene grafted with maleic anhydride with a melt index of 2.5 g / 10 min and a grafting degree of 1.5%, 0.8 parts by weight of monocarbodiimide, 0.3 parts by weight of pyromellitic anhydride, 0.3 parts by weight of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], and 0.9 parts by weight of 1,4-di(diallyl isocyanate) methylbenzene. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 175°C, the extrusion temperature was set to 165°C, and the screw extrusion speed was 165 rpm. The composite material was then dried at 65°C to obtain the inner layer special material.

[0172] Take 100 parts by weight of polylactic acid with a melt index of 3.5 g / 10 min and a number-average molecular weight of 230,000, 45 parts by weight of polybutylene adipate terephthalate with a melt index of 4.5 g / 10 min and a number-average molecular weight of 250,000 (molar ratio BA:BT = 55:45), 8 parts by weight of the above-mentioned composite carbon material, 2.5 parts by weight of polylactic acid grafted with citrate anhydride with a melt index of 2.5 g / 10 min and a grafting degree of 1.5%, 0.9 parts by weight of monocarbodiimide, and 0.25 parts by weight of... Pyromellitic anhydride, 0.3 parts by weight of N,N'-1,6-hexanedi[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], and 0.9 parts by weight of 1,4-di(diallyl isocyanate)methylbenzene were thoroughly mixed in a high-speed mixer, then melt-blended in a twin-screw extruder and extruded into granules. The blending temperature was set at 182°C, the extrusion temperature at 172°C, and the screw extrusion speed at 165 rpm. The composite material was then dried at 65°C to obtain a special material for the intermediate layer.

[0173] Take 100 parts by weight with a density of 0.945 g / cm³ 3 The high-density polyethylene has a melt flow index of 3.8 g / 10 min and a density of 0.915 g / cm³ per 12 parts by weight. 3 The mixture consisted of high-pressure polyethylene with a melt index of 3.5 g / 10 min, 2.5 parts by weight of polyethylene grafted with maleic anhydride and a melt index of 2.5 g / 10 min with a grafting degree of 1.5%, 0.6 parts by weight of orange-red environmentally friendly masterbatch, 0.6 parts by weight of calcium stearate, 0.8 parts by weight of erucamide, 0.3 parts by weight of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], and 0.9 parts by weight of 1,4-di(diallyl isocyanate) methylbenzene. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 175°C, the extrusion temperature at 165°C, and the screw extrusion speed at 165 rpm. The composite material was then dried at 65°C to obtain the outer layer special material.

[0174] The aforementioned special materials for each layer were placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature was set to 182℃, the screw extrusion speed to 110 rpm, the outer layer thickness to be 0.42 mm, the middle layer thickness to be 0.7 mm, and the inner layer thickness to be 1.1 mm. The prepared pipe was then subjected to an irradiation crosslinking device with an irradiation dose of 95 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promoted the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improved the overall performance of the composite pipe, including its heat resistance, ultimately resulting in an environmentally friendly thermally conductive composite pipe.

[0175] Tests showed that the degradation rate of the intermediate layer was 80.5%; the tensile strength of the composite pipe was 31.7 MPa, with a tensile strength retention rate of 93.8%; the elongation at break was 473%, with an elongation at break retention rate of 93.2%; the thermal conductivity was 2.08 W / (m·K); and the Vicat softening temperature was 123.4℃.

[0176] Example 3

[0177] First, 100 parts by weight of 400-mesh bamboo powder and 0.8 parts by weight of cobalt acetate were placed in 900 parts by weight of 97 wt% concentrated sulfuric acid and stirred for 5 hours at a stirring speed of 500 rpm. After the reaction was completed, 4500 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 7 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to remove sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 30 minutes at a calcination temperature of 350°C. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0178] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 25 parts by weight of carbon black with an average particle size of 35 nm, a DBP absorption value of 266 mL / 100 g, and a specific surface area of ​​190 m². 2 The mixture consisted of 3 parts by weight of double-walled carbon nanotubes with an outer diameter of 2.5 nm and 15 parts by weight of spherical micron-sized carbon powder with an average particle size of 2 μm. These were placed in 700 parts by weight of dimethylformamide solvent and sonicated for 30 min. Then, 200 parts by weight of tetraethylenepentamine and 1.5 parts by weight of N-hydroxysuccinimide were added, and the mixture was sonicated for another 30 min. The mixture was then stirred at 40 °C for 5 h, filtered using a vacuum filter, washed multiple times with deionized water, and dried at 70 °C to obtain the composite carbon material.

[0179] Take 100 parts by weight with a density of 0.950 g / cm³ 3 The high-density polyethylene has a melt flow index of 4.7 g / 10 min and a density of 0.925 g / cm³ per 15 parts by weight. 3The following materials were used: metallocene medium-density polyethylene with a melt index of 4.0 g / 10 min, 10 parts by weight of the above-mentioned compounded carbon material, 3 parts by weight of polyethylene grafted with octenyl succinic anhydride with a melt index of 3.0 g / 10 min and a grafting degree of 2%, 1 part by weight of poly(4-methoxy-4'-acryloyloxybenzoate), 0.8 parts by weight of sodium stearate, 1.3 parts by weight of oleamide, 0.5 parts by weight of octadecyl di-T-butyl-4-hydroxyhydrocinnamate, and 1.2 parts by weight of m-phenylene bismaleimide. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 180°C, the extrusion temperature was set to 170°C, and the screw extrusion speed was 180 rpm. The composite material was then dried at 70°C to obtain the inner layer special material.

[0180] Take 100 parts by weight of polylactic acid with a melt index of 4.0 g / 10 min and a number-average molecular weight of 250,000, 50 parts by weight of polybutylene adipate terephthalate with a melt index of 5.0 g / 10 min and a number-average molecular weight of 300,000 (molar ratio BA:BT = 50:50), 10 parts by weight of the above-mentioned compound carbon material, 3 parts by weight of polylactic acid grafted with maleic anhydride with a melt index of 3.0 g / 10 min and a grafting degree of 2%, and 1.3 parts by weight of polycarbonate with a number-average molecular weight of 9,000. Diimide, 0.32 parts by weight of styrene-glycidyl methacrylate copolymer, 0.5 parts by weight of octadecyl di-T-butyl-4-hydroxyhydrocinnamate, and 1.2 parts by weight of m-phenylene bismaleimide were thoroughly mixed in a high-speed mixer, then melt-blended in a twin-screw extruder and extruded into granules. The blending temperature was set to 185°C, the extrusion temperature was set to 175°C, and the screw extrusion speed was 180 rpm. The composite material was then dried at 70°C to obtain a special material for the intermediate layer.

[0181] Take 100 parts by weight with a density of 0.950 g / cm³ 3 The high-density polyethylene has a melt flow index of 4.7 g / 10 min and a density of 0.925 g / cm³ per 15 parts by weight. 3The mixture consisted of metallocene medium-density polyethylene with a melt index of 4.0 g / 10 min, 3 parts by weight of polyethylene grafted with octenyl succinic anhydride with a melt index of 3.0 g / 10 min and a grafting degree of 2%, 0.8 parts by weight of silver-gray environmentally friendly masterbatch, 0.8 parts by weight of sodium stearate, 1.3 parts by weight of oleamide, 0.5 parts by weight of octadecyl di-T-butyl-4-hydroxyhydrocinnamate, and 1.2 parts by weight of m-phenylene bismaleimide. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 180℃, the extrusion temperature was set to 170℃, and the screw extrusion speed was 180 rpm. The composite material was then dried at 70℃ to obtain the outer layer special material.

[0182] The aforementioned special materials for each layer were placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature was set to 185℃, the screw extrusion speed to 130 rpm, the outer layer thickness to be 0.45 mm, the middle layer thickness to be 0.8 mm, and the inner layer thickness to be 1.2 mm. The prepared pipe was then subjected to an irradiation crosslinking device with an irradiation dose of 110 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promoted the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improved the overall performance of the composite pipe, such as its heat resistance, ultimately resulting in an environmentally friendly thermally conductive composite pipe.

[0183] Tests showed that the degradation rate of the intermediate layer was 76.1%; the tensile strength of the composite pipe was 30.7 MPa, with a tensile strength retention rate of 94.5%; the elongation at break was 435%, with an elongation at break retention rate of 94.0%; the thermal conductivity was 2.78 W / (m·K); and the Vicat softening temperature was 123.8℃.

[0184] Example 4

[0185] First, 100 parts by weight of 450-mesh bamboo powder and 0.8 parts by weight of ferrous sulfate were placed in 950 parts by weight of 97.5 wt% concentrated sulfuric acid and stirred for 5.5 hours at a stirring speed of 550 rpm. After the reaction was completed, 4800 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 7.5 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to obtain sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 35 minutes at a calcination temperature of 380°C. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0186] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 28 parts by weight of carbon black with an average particle size of 38 nm, a DBP absorption value of 272 mL / 100 g, and a specific surface area of ​​200 m². 2 The mixture consisted of 3.5 parts by weight of multi-walled carbon nanotubes with an outer diameter of 9.0 nm and 18 parts by weight of spherical micron-sized carbon powder with an average particle size of 2.5 μm. These were placed in 770 parts by weight of anhydrous ethanol and sonicated for 35 min. Then, 235 parts by weight of pentaethylenehexamine and 1.7 parts by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine were added, and sonication continued for another 35 min. The mixture was then stirred at 45 °C for 5.5 h, filtered using a vacuum filter, washed multiple times with deionized water, and dried at 80 °C to obtain the composite carbon material.

[0187] Take 100 parts by weight with a density of 0.955 g / cm³ 3 The high-density polyethylene has a melt flow index of 5.4 g / 10 min and a density of 0.930 g / cm³ for 8 parts by weight. 3 Linear low-density polyethylene with a melt flow index of 4.5 g / 10 min and a density of 0.910 g / cm³ at 8 parts by weight. 3 The following materials were used: ethylene-octene copolymer with a melt index of 5.0 g / 10 min, 13 parts by weight of the above-mentioned modified compound carbon material, 3.5 parts by weight of polyethylene grafted ethylene methyl acrylate with a melt index of 3.5 g / 10 min and a graft degree of 2.5%, 1.5 parts by weight of dimethylbenzyl sorbitol, 0.8 parts by weight of barium stearate, 1.7 parts by weight of glyceryl stearate, 0.8 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, and 1.5 parts by weight of trimethylolpropane triacrylate. The materials were thoroughly mixed in a high-speed mixer, melt-blended in a twin-screw extruder, and then extruded and granulated. The blending temperature was set to 185°C, the extrusion temperature was set to 175°C, and the screw extrusion speed was 185 rpm. The composite material was then dried at 75°C to obtain the inner layer special material.

[0188] Take 100 parts by weight of polylactic acid with a melt index of 4.5 g / 10 min and a number average molecular weight of 280,000, 55 parts by weight of polybutylene adipate terephthalate with a melt index of 5.5 g / 10 min and a number average molecular weight of 350,000 (molar ratio BA:BT = 45:55), 13 parts by weight of the above-mentioned compound carbon material, 3.5 parts by weight of polylactic acid grafted with methyl methacrylate with a melt index of 3.5 g / 10 min and a grafting degree of 2.5%, and 1.6 parts by weight of phosphoric acid with a thickness of 2 nm. Zirconium nanosheets, 0.4 parts by weight of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 0.8 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, and 1.5 parts by weight of trimethylolpropane triacrylate were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 188°C, the extrusion temperature at 178°C, and the screw extrusion speed at 185 rpm. The composite material was then dried at 75°C to obtain a special material for the intermediate layer.

[0189] Take 100 parts by weight with a density of 0.955 g / cm³ 3 The high-density polyethylene has a melt flow index of 5.4 g / 10 min and a density of 0.930 g / cm³ for 8 parts by weight. 3 Linear low-density polyethylene with a melt flow index of 4.5 g / 10 min and a density of 0.910 g / cm³ at 8 parts by weight. 3 The mixture consisted of ethylene-octene copolymer with a melt index of 5.0 g / 10 min, 3.5 parts by weight of polyethylene grafted with ethylene methyl acrylate with a melt index of 3.5 g / 10 min and a graft degree of 2.5%, 0.8 parts by weight of pink environmentally friendly color masterbatch, 0.8 parts by weight of barium stearate, 1.7 parts by weight of glyceryl stearate, 0.8 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, and 1.5 parts by weight of trimethylolpropane triacrylate. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 185℃, the extrusion temperature was set to 175℃, and the screw extrusion speed was 185 rpm. The composite material was then dried at 75℃ to obtain the outer layer special material.

[0190] The aforementioned special materials for each layer were placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature was set to 187℃, the screw extrusion speed to 140 rpm, the outer layer thickness to be 0.47 mm, the middle layer thickness to be 0.9 mm, and the inner layer thickness to be 1.3 mm. The prepared pipe was then subjected to an irradiation crosslinking device with an irradiation dose of 125 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promoted the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improved the overall performance of the composite pipe, including its heat resistance, ultimately resulting in an environmentally friendly thermally conductive composite pipe.

[0191] Tests showed that the degradation rate of the intermediate layer was 70.9%; the tensile strength of the composite pipe was 29.8 MPa, with a tensile strength retention rate of 95.1%; the elongation at break was 398%, with an elongation at break retention rate of 94.8%; the thermal conductivity was 3.44 W / (m·K); and the Vicat softening temperature was 124.2℃.

[0192] Example 5

[0193] First, 100 parts by weight of 500-mesh bamboo powder, 0.5 parts by weight of nano-nickel oxide, and 0.5 parts by weight of ferric nitrate were placed in 1000 parts by weight of 98 wt% concentrated sulfuric acid and stirred for 6 hours at a stirring speed of 600 rpm. After the reaction was completed, 5000 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 8 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to remove sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 40 minutes at a temperature of 400°C. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0194] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 30 parts by weight of carbon black with an average particle size of 40 nm, a DBP absorption value of 280 mL / 100 g, and a specific surface area of ​​210 m². 2 The mixture consisted of 2 parts by weight of double-walled carbon nanotubes with an outer diameter of 4.0 nm, 2 parts by weight of multi-walled carbon nanotubes with an outer diameter of 10 nm, and 20 parts by weight of spherical micron-sized carbon powder with an average particle size of 3 μm. These were placed in a mixed solvent of 400 parts by weight of anhydrous ethanol and 400 parts by weight of dimethylformamide. After ultrasonic treatment for 40 min, 125 parts by weight of diethylenetriamine, 125 parts by weight of pentaethylenehexamine, 1 part by weight of 1-hydroxybenzotriazole, and 1 part by weight of N-hydroxysuccinimide were added. Ultrasonic treatment continued for another 40 min, followed by stirring at 50 °C for 6 h. The mixture was then filtered using a vacuum filter, washed multiple times with deionized water, and the resulting solid was dried at 80 °C to obtain the composite carbon material.

[0195] Take 100 parts by weight with a density of 0.960 g / cm³ 3 The high-density polyethylene has a melt flow index of 6.0 g / 10 min and a density of 0.925 g / cm³ per 10 parts by weight. 3 High-density polyethylene with a melt flow index of 5.0 g / 10 min and a density of 0.935 g / cm³ per 10 parts by weight. 3The composition includes: metallocene medium-density polyethylene with a melt flow index of 6.0 g / 10 min, 15 parts by weight of the above-mentioned compounded carbon material, 2 parts by weight of polyethylene grafted with itaconic anhydride with a melt flow index of 4.0 g / 10 min and a grafting degree of 3%, 2 parts by weight of polyethylene grafted with methyl methacrylate with a melt flow index of 4.0 g / 10 min and a grafting degree of 3%, 1 part by weight of poly(4-methoxy-4'-acryloyloxybenzoate), 1 part by weight of di(p-ethyldibenzylene)sorbitol, 0.5 parts by weight of cerium stearate, 0.5 parts by weight of polyethylene wax, 1 part by weight of erucamide, 1 part by weight of oleamide, and 0. 0.5 parts by weight of di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, 0.5 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, 1 part by weight of 1,4-di(diallyl isocyanate)methylbenzene, and 1 part by weight of trimethylolpropane trimethacrylate were thoroughly mixed in a high-speed mixer, then melt-blended in a twin-screw extruder and extruded into granules. The blending temperature was set at 190°C, the extrusion temperature at 180°C, and the screw extrusion speed at 200 rpm. The composite material was then dried at 80°C to obtain the inner layer special material.

[0196] Take 100 parts by weight of polylactic acid with a melt index of 5.0 g / 10 min and a number average molecular weight of 300,000, 60 parts by weight of polybutylene adipate terephthalate with a melt index of 6.0 g / 10 min and a number average molecular weight of 400,000 (molar ratio BA:BT = 40:60), 15 parts by weight of the above-mentioned composite carbon material, 2 parts by weight of polylactic acid grafted with maleic anhydride with a melt index of 4.0 g / 10 min and a graft degree of 3%, 2 parts by weight of polylactic acid grafted with glycidyl methacrylate with a melt index of 4.0 g / 10 min and a graft degree of 3%, 1 part by weight of polycarbodiimide with a number average molecular weight of 10,000, 1 part by weight of zirconium phosphate nanosheets with a thickness of 2 nm, and 0.25 parts by weight of styrene-methylpropene. The following materials were used: a copolymer of glycidyl ester, 0.25 parts by weight of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 0.5 parts by weight of di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, 0.5 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, 1 part by weight of 1,4-di(diallyl isocyanate)methylbenzene, and 1 part by weight of trimethylolpropane trimethacrylate. The materials were thoroughly mixed in a high-speed mixer, then melt-blended in a twin-screw extruder and extruded into granules. The blending temperature was set at 190°C, the extrusion temperature was set at 180°C, and the screw extrusion speed was 200 rpm. The composite material was then dried at 80°C to obtain a special material for the intermediate layer.

[0197] Take 100 parts by weight with a density of 0.960 g / cm³3 The high-density polyethylene has a melt flow index of 6.0 g / 10 min and a density of 0.925 g / cm³ per 10 parts by weight. 3 High-density polyethylene with a melt flow index of 5.0 g / 10 min and a density of 0.935 g / cm³ per 10 parts by weight. 3 The following are components: metallocene medium-density polyethylene with a melt index of 6.0 g / 10 min; 2 parts by weight of polyethylene grafted with itaconic anhydride (3% grafting degree) and a melt index of 4.0 g / 10 min; 2 parts by weight of polyethylene grafted with methyl methacrylate (3% grafting degree) and a melt index of 4.0 g / 10 min; 0.5 parts by weight of gold environmentally friendly masterbatch; 0.5 parts by weight of gray environmentally friendly masterbatch; 0.5 parts by weight of cerium stearate; 0.5 parts by weight of polyethylene wax; 1 part by weight of erucamide; 1 part by weight of oleamide; and 0.5 parts by weight of di(2-methyl- 5-tert-butyl-4-hydroxyphenyl) sulfide, 0.5 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, 1 part by weight of 1,4-di(diallyl isocyanate) methylbenzene, and 1 part by weight of trimethylolpropane trimethacrylate were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 190°C, the extrusion temperature at 180°C, and the screw extrusion speed at 200 rpm. The composite material was then dried at 80°C to obtain the outer layer special material.

[0198] The aforementioned special materials for each layer are placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature is set to 190℃, the screw extrusion speed is 150 rpm, the outer layer thickness is 0.50 mm, the middle layer thickness is 1.0 mm, and the inner layer thickness is 1.4 mm. The prepared pipe is then subjected to an irradiation crosslinking device with an irradiation dose of 140 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promotes the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improves the overall performance of the composite pipe, such as its heat resistance, ultimately obtaining an environmentally friendly thermally conductive composite pipe.

[0199] Tests showed that the degradation rate of the intermediate layer was 66.7%; the tensile strength of the composite pipe was 28.1 MPa, with a tensile strength retention rate of 95.8%; the elongation at break was 351%, with a tensile strength retention rate of 95.3%; the thermal conductivity was 4.25 W / (m·K); and the Vicat softening temperature was 124.9℃.

[0200] Comparative Example 1

[0201] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min, 10 parts by weight of 0.910 g / cm³ 3The following components were selected: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 5 parts by weight of commercially available pyrolytic bamboo charcoal, 2 parts by weight of polyethylene grafted with succinic anhydride and a melt index of 2.0 g / 10 min with a grafting degree of 1%, 0.5 parts by weight of n-hexyl-substituted oxalamide, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl distearate, and 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4- Thiamethoxane diethylene glycol ester and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 170°C, the extrusion temperature at 160°C, and the screw extrusion speed at 150 rpm. The composite material was then dried at 60°C to obtain the inner layer special material.

[0202] Take 100 parts by weight of polylactic acid with a melt index of 3.0 g / 10 min and a number-average molecular weight of 200,000, 40 parts by weight of polybutylene adipate terephthalate with a melt index of 4.0 g / 10 min and a number-average molecular weight of 200,000 (molar ratio BA:BT = 60:40), 5 parts by weight of commercially available pyrolytic bamboo charcoal, 2 parts by weight of polylactic acid grafted with succinic anhydride with a melt index of 2.0 g / 10 min and a grafting degree of 1%, 0.5 parts by weight of polycarbodiimide with a number-average molecular weight of 8000, and 0.2 parts by weight of 2,4-toluene. Diisocyanate, 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 180°C, the extrusion temperature at 170°C, and the screw extrusion speed at 150 rpm. The composite material was then dried at 60°C to obtain a special material for the intermediate layer.

[0203] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min and a density of 0.910 g / cm³ per 10 parts by weight. 3The following materials were used: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 2 parts by weight of polyethylene grafted with succinic anhydride and a melt index of 2.0 g / 10 min with a grafting degree of 1%, 0.5 parts by weight of purple environmentally friendly masterbatch, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl distearate, 0.1 parts by weight of thiadiglycol di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 170℃, the extrusion temperature was set at 160℃, and the screw extrusion speed was 150 rpm. The composite material was then dried at 60℃ to obtain the outer layer special material.

[0204] The aforementioned special materials for each layer are placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature is set to 180℃, the screw extrusion speed is 100 rpm, the outer layer thickness is 0.4 mm, the middle layer thickness is 0.6 mm, and the inner layer thickness is 1.0 mm. The prepared pipe is then subjected to an irradiation crosslinking device with an irradiation dose of 80 KGy to initiate crosslinking of the composite pipe to form a three-dimensional network structure. This promotes the compatibility and bonding strength of each layer, as well as the formation of a thermally conductive network, and effectively improves the overall performance of the composite pipe, such as its heat resistance, ultimately obtaining an environmentally friendly thermally conductive composite pipe.

[0205] Tests showed that the degradation rate of the intermediate layer was 93.3%; the tensile strength of the composite pipe was 28.5 MPa, with a tensile strength retention rate of 88.5%; the elongation at break was 388%, with an elongation at break retention rate of 88.0%; the thermal conductivity was 0.38 W / (m·K); and the Vicat softening temperature was 120.9℃.

[0206] A comparison of Example 1 and Example 1 shows that modifying carbon materials and using anti-hydrolysis agents can significantly reduce the degradation rate of the degradation layer, extend the service life, and improve the retention rate of mechanical properties of composite pipes. Using bamboo charcoal-based graphene and other materials as thermally conductive fillers, after compound modification, not only significantly improves the thermal conductivity of the pipes but also enhances their mechanical properties.

[0207] Comparative Example 2

[0208] First, 100 parts by weight of 500-mesh bamboo powder and 0.5 parts by weight of nano-nickel oxide were placed in 800 parts by weight of 96 wt% concentrated sulfuric acid and stirred for 4 hours at a stirring speed of 400 rpm. After the reaction was completed, 4000 parts by weight of deionized water were added to quench the reaction. During quenching, the reactor was cooled to ensure that the temperature was maintained at room temperature. After standing for 6 hours, the black foam suspended on the surface was removed, and the middle layer of sulfuric acid mixture was slowly extracted. The lower suspension was filtered to obtain the desired black powder. The first filtrate and the middle layer of sulfuric acid mixture were purified by vacuum distillation to remove sulfuric acid for reuse. The obtained black powder was washed until it was neutral, and then calcined in a vacuum muffle furnace for 20 minutes at a calcination temperature of 300℃. After cooling to room temperature, the powder was removed to obtain bamboo charcoal-based graphene oxide.

[0209] Take 100 parts by weight of the above-mentioned bamboo charcoal-based graphene oxide and 20 parts by weight of carbon black with an average particle size of 30 nm, a DBP absorption value of 250 mL / 100 g, and a specific surface area of ​​150 m². 2 2 parts by weight of single-walled carbon nanotubes and 10 parts by weight of spherical micron-sized carbon powder with an average particle size of 1 μm were placed in 600 parts by weight of methanol solvent and ultrasonically treated for 20 min. Then, 150 parts by weight of diethylenetriamine and 1 part by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine were added, and ultrasonic treatment was continued for another 20 min. After that, the mixture was stirred at 30 °C for 4 h and filtered with a vacuum filter. After washing with deionized water several times, the resulting solid was dried at 60 °C to obtain the composite carbon material.

[0210] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min, 10 parts by weight of 0.910 g / cm³ 3 The following materials were used: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 5 parts by weight of the above-mentioned compound carbon material, 0.5 parts by weight of n-hexyl-substituted oxalamide, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl bis-stearamide, 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione. The materials were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set to 170°C, the extrusion temperature was set to 160°C, and the screw extrusion speed was 150 rpm. The composite material was then dried at 60°C to obtain the inner layer special material.

[0211] Take 100 parts by weight of polylactic acid with a melt index of 3.0 g / 10 min and a number average molecular weight of 200,000, 40 parts by weight of polybutylene adipate terephthalate with a melt index of 4.0 g / 10 min and a number average molecular weight of 200,000 (molar ratio BA:BT = 60:40), 5 parts by weight of the above-mentioned composite carbon material, 0.2 parts by weight of 2,4-toluene diisocyanate, and 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)] Thiamethoxane diethylene glycol ester of 4-hydroxy-]phenylpropionate and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione were thoroughly mixed in a high-speed mixer, then melt-blended and extruded into granules in a twin-screw extruder. The blending temperature was set at 180°C, the extrusion temperature at 170°C, and the screw extrusion speed at 150 rpm. The composite material was then dried at 60°C to obtain a special material for the intermediate layer.

[0212] Take 100 parts by weight with a density of 0.940 g / cm³ 3 High-density polyethylene with a melt flow index of 3.0 g / 10 min and a density of 0.910 g / cm³ per 10 parts by weight. 3 The following materials were used: linear low-density polyethylene with a melt index of 3.0 g / 10 min, 0.5 parts by weight of purple environmentally friendly masterbatch, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl distearate, 0.1 parts by weight of di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionic acid thiadiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione. After the materials were fully mixed in a high-speed mixer, they were melt-blended in a twin-screw extruder and then extruded and granulated. The blending temperature was set at 170℃, the extrusion temperature was set at 160℃, and the screw extrusion speed was 150 rpm. The composite material was then dried at 60℃ to obtain a special material for the inner polyethylene layer.

[0213] The aforementioned special materials for each layer are placed into the hopper of a three-layer co-extrusion pipe extruder. The extruder processing temperature is set to 180℃, the screw extrusion speed is 100 rpm, the outer layer thickness is 0.4 mm, the middle layer thickness is 0.6 mm, and the inner layer thickness is 1.0 mm. This results in an environmentally friendly thermally conductive composite pipe.

[0214] Tests showed that the degradation rate of the intermediate layer was 89.8%; the tensile strength of the composite pipe was 31.6 MPa, with a tensile strength retention rate of 90.7%; the elongation at break was 536%, with an elongation at break retention rate of 90.3%; the thermal conductivity was 1.56 W / (m·K); and the Vicat softening temperature was 106.4℃.

[0215] A comparison of Comparative Example 2 and Example 1 shows that the use of anti-hydrolysis agent can significantly reduce the degradation rate of the degradation layer, extend the service life, and improve the retention rate of mechanical properties of composite pipes to a certain extent. After irradiation crosslinking treatment, the Vicat softening temperature of the pipe will be significantly increased, and the formed three-dimensional network structure will further promote the improvement of the thermal conductivity network, thus improving the thermal conductivity.

[0216] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An environmentally friendly thermally conductive composite pipe, characterized in that, It is made by co-extruding three layers of pipe material (inner layer, middle layer, and outer layer) and then cross-linking them by electron beam radiation. The inner layer material of the pipe comprises: high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant and sensitizer; The components of the intermediate layer material of the pipe include: polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer; The outer layer of the pipe material comprises: high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer; The components of the composite carbon material include: bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifiers, and catalysts.

2. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The bamboo charcoal-based graphene oxide is prepared by calcining the solid reaction product obtained by reacting bamboo powder and sulfuric acid in the presence of a metal compound catalyst.

3. The environmentally friendly thermally conductive composite pipe according to claim 2, characterized in that, The bamboo powder has a mesh size of 300-500 mesh; And / or, the concentration of the sulfuric acid is 96-98 wt%; And / or, the metal compound catalyst is one or more of nickel oxide, nickel nitrate, nickel chloride, cobalt nitrate, cobalt acetate, cobalt nitrate, ferric nitrate, and ferrous sulfate; And / or, the mass ratio of the bamboo powder, sulfuric acid and metal compound catalyst is 100:(800-1000):(0.5-1).

4. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The carbon black in the composite carbon material has a DBP absorption value of 250–280 mL / 100 g and a specific surface area of ​​150–210 m². 2 / g, with an average particle size of 30-40nm; And / or, the carbon nanotubes in the composite carbon material are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes; And / or, the average particle size of the spherical micron carbon powder in the composite carbon material is 1 to 3 μm; And / or, the surface modifier in the composite carbon material is one or more of diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, and pentaethylenehexamine; And / or, the catalyst in the composite carbon material is one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole and N-hydroxysuccinimide.

5. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The density of the high-density polyethylene in the inner layer of the pipe is 0.94–0.96 g / cm³. 3 The melt index at 190℃ and 2.16kg is 3-6 g / 10min; And / or, the toughening agent in the inner layer of the pipe is one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer; And / or, the compatibilizer in the inner layer of the pipe is one or more of the following: polyethylene grafted with succinic anhydride, polyethylene grafted with citraconic anhydride, polyethylene grafted with itaconic anhydride, polyethylene grafted with octenoyl succinic anhydride, polyethylene grafted with maleic anhydride, polyethylene grafted with glycidyl methacrylate, polyethylene grafted with methyl ethylene acrylate, polyethylene grafted with methyl methacrylate, and polyethylene grafted with butyl methacrylate. And / or, the nucleating agent in the inner layer of the pipe is one or more of the following: n-hexyl-substituted oxalamide, cyclohexyl-substituted oxalamide, poly(4-methoxy)-diphenoloxycarbonylphenol acrylate, poly(4-methoxy-4'-acryloyloxybenzoate), benzoimidazolinone, isoindoleone, dimethylbenzyl sorbitol, di(p-ethyldibenzyl)sorbitol, dichlorobenzyl sorbitol, and sodium benzoate; And / or, the dispersant in the inner layer of the pipe is one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax; And / or, the lubricant in the inner layer of the pipe is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate; And / or, the antioxidant in the inner layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamate) pentaerythritol ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine; And / or, the sensitizer in the inner layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

6. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The polylactic acid in the intermediate layer of the pipe has a number-average molecular weight of 200,000 to 300,000 and a melt index of 3 to 5 g / 10 min at 190°C and 2.16 kg. And / or, the number-average molecular weight of polybutylene adipate in the intermediate layer of the pipe is 200,000 to 400,000, and the melt index is 4 to 6 g / 10 min at 190°C and 2.16 kg. And / or, the compatibilizer in the intermediate layer of the pipe is one or more of the following: polylactic acid grafted with succinic anhydride, polylactic acid grafted with citraconic anhydride, polylactic acid grafted with itaconic anhydride, polylactic acid grafted with octenoyl succinic anhydride, polylactic acid grafted with maleic anhydride, polylactic acid grafted with glycidyl methacrylate, polylactic acid grafted with ethylene methyl acrylate, polylactic acid grafted with methyl methacrylate, and polylactic acid grafted with butyl methacrylate. And / or, the water-resistant agent in the intermediate layer of the pipe is one or more of polycarbodiimide, monocarbodiimide and zirconium phosphate nanosheets; And / or, the chain extender in the intermediate layer of the pipe is one or more of 2,4-toluene diisocyanate, pyromellitic anhydride, ethylene-glycidyl methacrylate copolymer, styrene-glycidyl methacrylate copolymer and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; And / or, the antioxidant in the intermediate layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine; And / or, the sensitizer in the intermediate layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

7. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The high-density polyethylene in the outer layer of the pipe has a density of 0.94–0.96 g / cm³. 3 The melt index at 190℃ and 2.16kg is 3-6 g / 10min; And / or, the toughening agent in the outer layer of the pipe is one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer; And / or, the compatibilizer in the outer layer of the pipe is one or more of the following: polyethylene grafted with succinic anhydride, polyethylene grafted with citraconic anhydride, polyethylene grafted with itaconic anhydride, polyethylene grafted with octenoyl succinic anhydride, polyethylene grafted with maleic anhydride, polyethylene grafted with glycidyl methacrylate, polyethylene grafted with methyl ethylene acrylate, polyethylene grafted with methyl methacrylate, and polyethylene grafted with butyl methacrylate. And / or, the color of the masterbatch in the outer layer of the pipe is one or more of the following: black, purple, orange-red, orange-yellow, bright red, pink, pink, rose red, gray, silver-gray, dark gray, white, grass green, dark green, sky blue, brown, gold, and coffee. And / or, the dispersant in the outer layer of the pipe is one or more of stearic acid, zinc stearate, calcium stearate, magnesium stearate, sodium stearate, barium stearate, praseodymium stearate, lanthanum stearate, cerium stearate and polyethylene wax; And / or, the lubricant in the outer layer of the pipe is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate; And / or, the antioxidant in the outer layer of the pipe is one or more of N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, di[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, pentaerythritol tetra-(dibutylhydroxyhydrocinnamate) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazine; And / or, the sensitizer in the outer layer of the pipe is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-di(diallyl isocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

8. The environmentally friendly thermally conductive composite pipe according to claim 1, characterized in that, The mass ratio of high-density polyethylene, compound carbon material, toughening agent, compatibilizer, nucleating agent, dispersant, lubricant, antioxidant and sensitizer in the inner layer material of the pipe is 100:(5~15):(10~20):(2~4):(0.5~2):(0.5~1):(0.5~2):(0.1~1):(0.5~2); And / or, the mass ratio of polylactic acid, polybutylene adipate terephthalate, compound carbon material, compatibilizer, water-resistant agent, chain extender, antioxidant and sensitizer in the intermediate layer material of the pipe is 100:(40~60):(5~15):(2~4):(0.5~2):(0.2~0.5):(0.1~1):(0.5~2); And / or, the mass ratio of high-density polyethylene, toughening agent, compatibilizer, color masterbatch, dispersant, lubricant, antioxidant and sensitizer in the outer layer material of the pipe is 100:(10~20):(2~4):(0.5~1):(0.5~1):(0.5~2):(0.1~1):(0.5~2); And / or, the mass ratio of bamboo charcoal-based graphene oxide, carbon black, carbon nanotubes, spherical micron carbon powder, surface modifier and catalyst in the composite carbon material is 100:(20-30):(2-4):(10-20):(150-250):(1-2).

9. A method for preparing an environmentally friendly thermally conductive composite pipe according to any one of claims 1 to 8, characterized in that, Includes the following steps: The inner layer material, the middle layer material, and the outer layer material of the pipe are added to the hopper of the three-layer co-extrusion pipe extruder for three-layer co-extrusion to obtain a three-layer co-extruded pipe. The three-layer co-extruded pipe is cross-linked by electron beam radiation to obtain an environmentally friendly thermally conductive composite pipe.

10. The preparation method according to claim 9, characterized in that, The irradiation dose for electron beam crosslinking is 80–140 kGy.