High-thermal-conductivity composite pipe and preparation method thereof

Abstract

The invention belongs to the field of pipes, and particularly relates to a high-thermal-conductivity composite pipe and a preparation method thereof. The high-thermal-conductivity 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, carrying out annular pulse electric field treatment at a die orifice of an extruder, and then carrying out electron beam radiation crosslinking, the inner layer material of the pipe is prepared from high-density polyethylene, a modified compound carbon material, a flexibilizer, a compatibilizer, a melt index regulator, a nucleating agent, a dispersing agent, a lubricating agent, an antioxidant and a sensitizing agent; the middle layer material of the pipe comprises an ethylene-vinyl alcohol copolymer, a modified compound carbon material, a compatibilizer, an antioxidant and a sensitizer; the outer layer material of the pipe is prepared from high-density polyethylene, a modified compound carbon material, a toughening agent, a compatibilizer, a melt index regulator, a nucleating agent, a dispersing agent, a lubricating agent, an antioxidant and a sensitizing agent. The composite pipe provided by the invention has good heat-conducting property, heat resistance and mechanical strength, and is low in preparation cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of pipe materials, and particularly relates to a high-thermal-conductivity composite pipe material and a preparation method thereof. BACKGROUND

[0002] At present, the ground heating plastic pipe material mainly uses polyethylene pipe, but the thermal conductivity of polyethylene is low, and improving the thermal conductivity of the pipe material is the research focus in the field. Currently, a common method for improving the thermal conductivity of the polyethylene pipe material is to add thermal conductive fillers, such as aluminum oxide, boron nitride, graphite, etc. However, when the amount of the fillers is high, the mechanical properties and the environmental stress cracking resistance of the pipe material are reduced, and brittle cracking easily occurs at low temperatures, which is not suitable for applications such as conveying fluid under wide use temperature and under belt pressure.

[0003] In addition, the heat resistance of polyethylene is poor, which is one of the problems limiting its wide application in the field of ground heating. By physical or chemical crosslinking, a three-dimensional network structure is formed between polyethylene molecules, which can significantly improve the heat resistance, and therefore crosslinked polyethylene pipe materials have been widely used in ground heating systems. Currently, the commonly used crosslinked polyethylene includes peroxide crosslinking and silane crosslinking. However, the peroxide crosslinked pipe material has problems such as unstable quality or uneven crosslinking due to the preparation process, and the production of the silane crosslinked pipe material is difficult and the cost is high. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a high-thermal-conductivity composite pipe material and a preparation method thereof. The composite pipe material provided by the present application has good thermal conductivity, heat resistance and mechanical strength, and the preparation cost is low.

[0005] The present application provides a high-thermal-conductivity composite pipe material, which is prepared by three-layer co-extrusion of a pipe inner layer material, a pipe middle layer material and a pipe outer layer material, and then performing annular pulse electric field treatment at the die head of the extruder, and then performing electron beam radiation crosslinking.

[0006] The components of the pipe inner layer material include high-density polyethylene, modified complex carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer.

[0007] The components of the pipe middle layer material include ethylene-vinyl alcohol copolymer, modified complex carbon material, compatibilizer, antioxidant and sensitizer.

[0008] The components of the pipe outer layer material include high-density polyethylene, modified complex carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer.

[0009] The components of the modified complex carbon material include carbon black, micro-nano carbon mixture, surface modifier and catalyst, and the micro-nano carbon mixture includes nano carbon material and micro carbon material.

[0010] Preferably, the DBP absorption value of the carbon black in the modified compound carbon material is 250-280 mL / 100 g, the specific surface area is 150-210 m 2 / g, and the average particle size is 30-40 nm.

[0011] Preferably, the nano-carbon material in the modified compound carbon material is one or more of single-layer graphene, multi-layer graphene, graphene oxide, reduced graphene oxide, graphyne, single-walled carbon nanotube, double-walled carbon nanotube, and multi-walled carbon nanotube.

[0012] Preferably, the micro-carbon material in the modified compound carbon material is one or more of silicon carbide powder, natural flake graphite powder, artificial graphite powder, pyrolytic graphite powder, expanded graphite powder, spherical graphite powder, spherical micro-carbon powder, needle-shaped micro-carbon powder, fibrous micro-carbon powder, and carbon fiber powder.

[0013] Preferably, the surface modifier in the modified compound carbon material is one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0014] Preferably, the catalyst in the modified compound carbon material is one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole, and N-hydroxysuccinimide.

[0015] Preferably, the mass ratio of the carbon black, the micro-nano carbon mixture, the surface modifier, and the catalyst in the modified compound carbon material is 100:(15-25):(150-250):(1-2); and the mass ratio of the nano-carbon material and the micro-carbon material in the micro-nano carbon mixture is (1-2):1.

[0016] Preferably, the density of the high-density polyethylene in the inner layer material and the outer layer material of the pipe is 0.94-0.96 g / cm 3 , and the melt index under the condition of 190°C and 2.16 kg is 3-6 g / 10 min.

[0017] Preferably, the toughening agent in the inner layer material and the outer layer material of the pipe is one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer.

[0018] and / or the compatibilizer in the pipe inner layer material and the pipe outer layer material is one or more of polyethylene grafted succinic anhydride, polyethylene grafted citraconic anhydride, polyethylene grafted itaconic anhydride, polyethylene grafted octenyl succinic anhydride, polyethylene grafted maleic anhydride, polyethylene grafted glycidyl methacrylate, polyethylene grafted ethylene methyl acrylate, polyethylene grafted methyl methacrylate, and polyethylene grafted butyl methacrylate;

[0019] and / or the melt index modifier in the pipe inner layer material and the pipe outer layer material is CYD-P214;

[0020] and / or the nucleating agent in the pipe inner layer material and the pipe outer layer material is one or more of n-hexyl substituted oxamide, cyclohexyl substituted oxamide, poly 4-(4-methoxy)-diphenoloxalate acrylate, poly 4-methoxy-4'-acryloyloxybenzoic acid phenyl ester, benzimidazolone, isoindolinone, benzene di-p-methyl benzyl acetal sorbitol, di(p-ethyl dibenzylidene acetal) sorbitol, di-p-chlorobenzyl acetal sorbitol, and sodium benzoate;

[0021] and / or the dispersing agent in the pipe inner layer material and the pipe outer layer material 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;

[0022] and / or the lubricant in the pipe inner layer material and the pipe outer layer material is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate, and pentaerythritol stearate;

[0023] and / or the antioxidant in the pipe inner layer material and the pipe outer layer material is one or more of N,N'-1,6-hexylidenebis[3,5-di(1,1-dimethylethyl)-4-hydroxybenzylideneamino]carboxamide, octadecyl di-T-butyl-4-hydroxyhydrocinnamate, bis[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]benzylideneamino]thiodiglycolate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-T-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-T-butylphenyl)phosphite, bis(2-methyl-5-T-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamate) pentaerythritol, and 3-(3,5-di-T-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-T-butyl-4-hydroxyphenyl)propionyl] propionohydrazide;

[0024] and / or the sensitizer in the pipe inner layer material and the pipe outer layer material is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-bis(diallylisocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0025] Preferably, the mass ratio of the high-density polyethylene, the modified composite carbon material, the toughening agent, the compatibilizer, the melt index modifier, the nucleating agent, the dispersant, the lubricant, the antioxidant, and the sensitizer in the pipe inner layer material is 100:(6-16):(10-20):(2-4):(0.1-0.5):(0.5-2):(0.5-1):(0.5-2):(0.1-1):(0.5-2).

[0026] Preferably, the content of the repeating unit corresponding to the ethylene structure in the ethylene-vinyl alcohol copolymer in the pipe intermediate layer material is 25-35 wt%;

[0027] and / or the compatibilizer in the pipe intermediate layer material is one or more of ethylene-vinyl alcohol copolymer grafted succinic anhydride, ethylene-vinyl alcohol copolymer grafted citraconic anhydride, ethylene-vinyl alcohol copolymer grafted itaconic anhydride, ethylene-vinyl alcohol copolymer grafted octenyl succinic anhydride, ethylene-vinyl alcohol copolymer grafted maleic anhydride, ethylene-vinyl alcohol copolymer grafted glycidyl methacrylate, ethylene-vinyl alcohol copolymer grafted ethylene methyl acrylate, ethylene-vinyl alcohol copolymer grafted methyl methacrylate, and ethylene-vinyl alcohol copolymer grafted butyl methacrylate;

[0028] and / or the antioxidant in the pipe intermediate layer material is one or more of N,N'-1,6-hexylidenebis[3,5-bis(1,1-dimethylethyl)-4-hydroxybenzamidine], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, bis[3,5-bis-(1,1-dimethylethyl)-4-hydroxy-]benzenepropanoic acid thiodiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-t-butylphenyl) phosphite, bis(2-methyl-5-t-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamate) pentaerythritol ester, and 3-(3,5-di-t-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl] propionohydrazide;

[0029] And / or, the sensitizer in the pipe intermediate layer material is one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-bis(diallylisocyanate) methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0030] Preferably, the mass ratio of the ethylene-vinyl alcohol copolymer, the modified composite carbon material, the compatibilizer, the antioxidant, and the sensitizer in the pipe intermediate layer material is 100:(3-5):(2-4):(0.1-1):(0.5-2).

[0031] The application provides a preparation method of the high-thermal-conductivity composite pipe material.

[0032] The pipe inner layer material, the pipe intermediate layer material, and the pipe outer layer material are added to the hoppers of the three-layer co-extrusion pipe extruder for three-layer co-extrusion, and a ring-shaped pulse electric field is applied at the die of the extruder during the extrusion process to obtain a three-layer co-extrusion pipe material.

[0033] The three-layer co-extrusion pipe material is subjected to electron beam radiation crosslinking to obtain the high-thermal-conductivity composite pipe material.

[0034] Preferably, the electric field strength of the ring-shaped pulse electric field is 10-14 kV / mm, the pulse width is 0.5-1 μs, and the pulse frequency is 500-1000 Hz.

[0035] Preferably, the irradiation dose of the electron beam radiation crosslinking is 80-140 kGy.

[0036] Compared with the prior art, the application provides a high-thermal-conductivity composite pipe and a preparation method thereof. The high-thermal-conductivity composite pipe is prepared by three-layer co-extrusion of pipe inner layer material, pipe middle layer material and pipe outer layer material, annular pulse electric field treatment at an extruder die and electron beam radiation crosslinking. The pipe inner layer material comprises high-density polyethylene, modified complex carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer. The pipe middle layer material comprises ethylene-vinyl alcohol copolymer, modified complex carbon material, compatibilizer, antioxidant and sensitizer. The pipe outer layer material comprises high-density polyethylene, modified complex carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer. The modified complex carbon material comprises carbon black, micro-nano carbon mixture, surface modifier and catalyst, and the micro-nano carbon mixture comprises nano carbon material and micro carbon material. The application improves the thermal conductivity of the composite pipe by adopting carbon material complex modification, constructing ordered deflection structure and introducing crosslinking network, and improves the mechanical properties, heat resistance and other comprehensive properties of the composite pipe, and effectively reduces the preparation cost. Specifically, different dimension and structure of the thermal conductive carbon material are selected for complex modification, carbon black grafting is formed by complex modification, effective thermal conductive path is constructed by bonding connection, and the compatibility with the polyethylene matrix is improved; the complementary effect of different carbon materials is used to form a more perfect thermal conductive network at a low addition content, the mechanical properties are improved while the thermal conductivity is improved, and the thermal conductive pipe with excellent comprehensive properties is prepared; the melt viscosity is reduced by using the melt index regulator, the deflection time of the carbon material is shortened by cooperating with the pulse alternating current field emitter, the ordered deflection of the carbon material is realized, and the radial thermal conductivity is significantly improved; the radiation crosslinking treatment is performed by using the high-energy electron beam to form a three-dimensional network structure, the heat resistance and other properties of the composite pipe are greatly improved, and the formation of the thermal conductive network is promoted, and the thermal conductivity of the pipe is further improved. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0038] The application provides a high-thermal-conductivity composite pipe, which is prepared by three-layer co-extrusion of pipe inner layer material, pipe middle layer material and pipe outer layer material, annular pulse electric field treatment at an extruder die and electron beam radiation crosslinking.

[0039] The composition of the pipe inner layer material comprises high-density polyethylene, modified compound carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer;

[0040] The composition of the pipe intermediate layer material comprises ethylene-vinyl alcohol copolymer, modified compound carbon material, compatibilizer, antioxidant and sensitizer;

[0041] The composition of the pipe outer layer material comprises high-density polyethylene, modified compound carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer;

[0042] The composition of the modified compound carbon material comprises carbon black, micro-nano carbon mixture, surface modifier and catalyst, and the micro-nano carbon mixture comprises nano carbon material and micro carbon material.

[0043] In the composite pipe provided by the application, the DBP absorption value (dibutyl phthalate absorption value) of the carbon black in the modified compound carbon material is preferably 250-280 mL / 100 g, and can be specifically 250 mL / 100 g, 255 mL / 100 g, 260 mL / 100 g, 265 mL / 100 g, 270 mL / 100 g, 275 mL / 100 g, 280 mL / 100 g, or the like; the specific surface area of the carbon black is preferably 150-210 m 2 / g, and can be specifically 150 m 2 / g, 155 m 2 / g, 160 m 2 / g, 165 m 2 / g, 170 m 2 / g, 175 m 2 / g, 180 m 2 / g, 185 m 2 / g, 190 m 2 / g, 195 m 2 / g, 200 m 2 / g, 205 m 2 / g, or 210 m 2 / g; and the average particle size of the carbon black is preferably 30-40 nm, and can be specifically 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, or 40 nm.

[0044] In the composite pipe provided by the present application, in the modified and compounded carbon material, the nano carbon material in the micro-nano carbon mixture is preferably one or more of single-layer graphene, multi-layer graphene, graphene oxide, reduced graphene oxide, graphyne, single-walled carbon nanotube, double-walled carbon nanotube and multi-walled (wall layer is more than three layers) carbon nanotube; wherein the thickness of the single-layer graphene is preferably 0.1-0.5 nm, more preferably 0.3 nm; the thickness of the multi-layer graphene is preferably 3-7 nm, more preferably 5 nm; the thickness of the graphene oxide is preferably 5-10 nm, more preferably 8 nm; the thickness of the reduced graphene oxide is preferably 5-10 nm, more preferably 8 nm; the thickness of the graphyne is preferably 15-30 nm, more preferably 20 nm; the outer diameter of the single-walled carbon nanotube is preferably 1-3 nm, more preferably 2 nm; the outer diameter of the double-walled carbon nanotube is preferably 5-10 nm, more preferably 8 nm; the outer diameter of the multi-walled carbon nanotube is preferably 5-10 nm, more preferably 8 nm.

[0045] In the composite pipe provided by the present application, in the modified and compounded carbon material, the micro carbon material in the micro-nano carbon mixture is preferably one or more of silicon carbide micro powder, natural flake graphite micro powder, artificial graphite micro powder, pyrolytic graphite micro powder, expanded graphite micro powder, spherical graphite micro powder, spherical micro carbon powder, needle-shaped micro carbon powder, fibrous micro carbon powder and carbon fiber powder; the particle size (spherical material), thickness (sheet material) or diameter (needle / linear material) of the micro carbon material is preferably 1-5 μm, and can be specifically 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, 2.3 μm, 2.5 μm, 2.7 μm, 3 μm, 3.2 μm, 3.5 μm, 3.7 μm, 4 μm, 4.2 μm, 4.5 μm, 4.7 μm or 5 μm.

[0046] In the composite pipe provided by the present application, in the modified and compounded carbon material, the mass ratio of the nano carbon material and the micro carbon material in the micro-nano carbon mixture is preferably (1-2):1, and can be specifically 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1.

[0047] In the composite pipe provided by the present application, in the modified and compounded carbon material, the mass ratio of the micro-nano carbon mixture and the carbon black is preferably (15-25):100, and can be specifically 15:100, 16:100, 17:100, 18:100, 19:100, 20:100, 21:100, 22:100, 23:100, 24:100 or 25:100.

[0048] In the composite pipe provided by the present application, in the modified complex carbon material, the surface modifier is preferably one or more of diethylene triamine, triethylene tetramine, tetraethylene pentamine and pentaethylene hexamine.

[0049] In the composite pipe provided by the present application, in the modified complex carbon material, the mass ratio of the surface modifier to carbon black is preferably (150-250):100, and specifically can be 150:100, 160:100, 170:100, 180:100, 190:100, 200:100, 210:100, 220:100, 230:100, 240:100 or 250:100.

[0050] In the composite pipe provided by the present application, in the modified complex carbon material, the catalyst is preferably one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole and N-hydroxysuccinimide.

[0051] In the composite pipe provided by the present application, in the modified complex carbon material, the mass ratio of the catalyst to carbon black is preferably (1-2):100, and specifically can be 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.

[0052] In the composite pipe provided by the present application, the modified complex carbon material is preferably prepared by mixing and reacting the carbon black, the micro-nano carbon mixture, the surface modifier and the catalyst in a solvent, followed 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 carbon black is preferably (500-600):100, and specifically can be 500:100, 510:100, 520:100, 530:100, 540:100, 550:100, 560:100, 570:100, 580:100, 590:100 or 600:100; the temperature of the mixing reaction is preferably 30-50℃, and specifically can be 30℃, 35℃, 40℃, 45℃ or 50℃; the time of the mixing reaction is preferably 4-6h, and specifically can be 4h, 4.5h, 5h, 5.5h or 6h; and the temperature of the drying is preferably 60-80℃, and specifically can be 60℃, 65℃, 70℃, 75℃ or 80℃.

[0053] In the composite pipe provided by the present application, in the pipe inner layer material and the pipe outer layer material, the density of the high-density polyethylene is preferably 0.94-0.96g / cm 3 , and specifically can be 0.94g / cm 30.95 g / cm3, or 0.96 g / cm3. 3 0.945 g / cm3, or 0.95 g / cm3. 3 0.947 g / cm3, or 0.95 g / cm3. 3 0.95 g / cm3, or 0.96 g / cm3. 3 0.952 g / cm3, or 0.96 g / cm3. 3 0.955 g / cm3, or 0.96 g / cm3. 3 0.957 g / cm3, or 0.96 g / cm3. 3 0.95 g / cm3, or 0.96 g / cm3. 3 The high-density polyethylene has a melt index of 3-6 g / 10 min, preferably 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, 5 g / 10 min, 5.2 g / 10 min, 5.5 g / 10 min, 5.7 g / 10 min, or 6 g / 10 min at 190°C and 2.16 kg.

[0054] In the composite pipe provided by the application, the mass ratio of the high-density polyethylene to the modified composite carbon material in the inner layer material and the outer layer material of the pipe is preferably 100:(6-16), and specifically 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, or 100:16.

[0055] In the composite pipe provided by the application, the toughening agent in the inner layer material and the outer layer material of the pipe is preferably one or more of linear low-density polyethylene, high-pressure polyethylene, metallocene medium-density polyethylene, and ethylene-octene random copolymer. The linear low-density polyethylene has a density of 0.91-0.93 g / cm3, preferably 0.91 g / cm3, 0.915 g / cm3, 0.92 g / cm3, 0.925 g / cm3, or 0.93 g / cm3. 3 3 3 3 3 3 The linear low-density polyethylene has a melt index of 3-5 g / 10 min, preferably 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, or 5 g / 10 min at 190°C and 2.16 kg. The high-pressure polyethylene has a density of 0.91-0.925 g / cm3, preferably 0.91 g / cm3, 0.915 g / cm3, 0.92 g / cm3, or 0.925 g / cm3. 3 3 3 3 ​​​​​​​​or 0.925 g / cm 3 ; the high pressure polyethylene preferably has a melt index of 3 to 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 at 190°C and 2.16 kg; the metallocene medium density polyethylene preferably has a density of 0.925 to 0.935 g / cm 3 , specifically 0.925 g / cm 3 , 0.93 g / cm 3 , or 0.935 g / cm 3 ; the metallocene medium density polyethylene preferably has a melt index of 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 at 190°C and 2.16 kg; the ethylene-octene random copolymer preferably has a density of 0.89 to 0.92 g / cm 3 , specifically 0.89 g / cm 3 , 0.9 g / cm 3 , 0.91 g / cm 3 , or 0.92 g / cm 3 ; the ethylene-octene random copolymer preferably has a melt index of 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 at 190°C and 2.16 kg.

[0056] In the composite pipe provided by the present application, the mass ratio of the toughening agent to the high density polyethylene in the inner layer material and the outer 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.

[0057] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the compatibilizer is preferably one or more of polyethylene graft succinic anhydride, polyethylene graft citraconic anhydride, polyethylene graft itaconic anhydride, polyethylene graft octenyl succinic anhydride, polyethylene graft maleic anhydride, polyethylene graft glycidyl methacrylate, polyethylene graft ethylene methyl acrylate, polyethylene graft methyl methacrylate and polyethylene graft butyl methacrylate; the grafting degree of the polyethylene graft is preferably 1-3%, and specifically can be 1%, 1.2%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7% or 3%; the number average molecular weight of the polyethylene graft is 200-300 thousand, and specifically can be 200 thousand, 210 thousand, 220 thousand, 230 thousand, 240 thousand, 250 thousand, 260 thousand, 270 thousand, 280 thousand, 290 thousand or 300 thousand.

[0058] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the mass ratio of the compatibilizer to the high-density polyethylene is preferably (2-4):100, and specifically can be 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.

[0059] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the brand of the melt index modifier is preferably CYD-P214, and the melt index modifier with the above brand is provided by Weihai Chen Yuan Molecular New Material Co., Ltd.

[0060] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the mass ratio of the melt index modifier to the high-density polyethylene is preferably (0.1-0.5):100, and specifically can be 0.1:100, 0.15:100, 0.2:100, 0.25:100, 0.3:100, 0.35:100, 0.4:100, 0.45:100 or 0.5:100.

[0061] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the nucleating agent is preferably one or more of n-hexyl-substituted oxamide, cyclohexyl-substituted oxamide, poly 4-(4-methoxy)-diphenoloxalate acrylate, poly 4-methoxy-4'-acryloyloxybenzoic acid phenyl ester, benzimidazolone, isoindolinone, benzene di-p-methyl benzyl acetal sorbitol, di(p-ethyl dibenzylidene acetal) sorbitol, di-p-chlorobenzyl acetal sorbitol and sodium benzoate.

[0062] In the composite pipe provided by the present application, the mass ratio of the nucleating agent to the high-density polyethylene in the inner layer material and the outer layer material of the pipe is preferably (0.5-2):100, and specifically can be 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.

[0063] In the composite pipe provided by the present application, the dispersing agent in the inner layer material and the outer 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.

[0064] In the composite pipe provided by the present application, the mass ratio of the dispersing agent to the high-density polyethylene in the inner layer material and the outer layer material of the pipe is preferably (0.5-1):100, and specifically can be 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.

[0065] In the composite pipe provided by the present application, the lubricant in the inner layer material and the outer layer material of the pipe is preferably one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate.

[0066] In the composite pipe provided by the present application, the mass ratio of the lubricant to the high-density polyethylene in the inner layer material and the outer layer material of the pipe is preferably (0.5-2):100, and specifically can be 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.

[0067] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the antioxidant is preferably one or more of N,N'-1,6-hexylidenebis[3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, bis[3,5-bis-(1,1-dimethylethyl)-4-hydroxy-]benzenepropanoic acid thiodiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-t-butylphenyl) phosphite, bis(2-methyl-5-t-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutylhydroxyhydrocinnamic acid) pentaerythritol ester, and 3-(3,5-di-t-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl] propionohydrazide.

[0068] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the mass ratio of the antioxidant to the high-density polyethylene is preferably (0.1-1):100, and specifically can be 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.

[0069] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the sensitizer is preferably one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-bis(diallylisocyanate) methylbenzene, m-phenylenedimaleimide, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0070] In the composite pipe provided by the present application, in the inner layer material and the outer layer material of the pipe, the mass ratio of the sensitizer to the high-density polyethylene is preferably (0.5-2):100, and specifically can be 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.

[0071] In the composite pipe provided by the present application, the inner layer material and the outer layer material of the pipe are preferably prepared by melt blending and extruding the high-density polyethylene, the modified composite carbon material, the toughening agent, the compatibilizer, the melt index modifier, the nucleating agent, the dispersing agent, the lubricant, the antioxidant and the sensitizer in an extruder, and then granulating and drying. The temperature of the melt blending is preferably 170-190°C, and can be 170°C, 175°C, 180°C, 185°C or 190°C. The temperature of the extrusion is preferably 160-180°C, and can be 160°C, 165°C, 170°C, 175°C or 180°C. The temperature of the drying is preferably 60-80°C, and can be 60°C, 65°C, 70°C, 75°C or 80°C.

[0072] In the composite pipe provided by the present application, the content of the repeating unit corresponding to the ethylene structure in the ethylene-vinyl alcohol copolymer in the intermediate layer material of the pipe is preferably 25-35wt%, and can be 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt% or 35wt%. The melt index of the ethylene-vinyl alcohol copolymer at 190°C and under a load of 2.16kg is preferably 2-4g / 10min, and can be 2g / 10min, 2.2g / 10min, 2.5g / 10min, 2.7g / 10min, 3g / 10min, 3.2g / 10min, 3.5g / 10min, 3.7g / 10min or 4g / 10min.

[0073] In the composite pipe provided by the present application, the mass ratio of the ethylene-vinyl alcohol copolymer to the modified composite carbon material in the intermediate layer material of the pipe is preferably 100:(3-5), and can be 100:3, 100:3.2, 100:3.5, 100:3.7, 100:4, 100:4.2, 100:4.5, 100:4.7 or 100:5.

[0074] In the composite pipe provided by the present application, in the intermediate layer material of the pipe, the compatibilizer is preferably one or more of ethylene-vinyl alcohol copolymer grafts, more preferably ethylene-vinyl alcohol copolymer graft succinic anhydride, ethylene-vinyl alcohol copolymer graft citraconic anhydride, ethylene-vinyl alcohol copolymer graft itaconic anhydride, ethylene-vinyl alcohol copolymer graft octenyl succinic anhydride, ethylene-vinyl alcohol copolymer graft maleic anhydride, ethylene-vinyl alcohol copolymer graft glycidyl methacrylate, ethylene-vinyl alcohol copolymer graft ethylene methyl acrylate, ethylene-vinyl alcohol copolymer graft methyl methacrylate and ethylene-vinyl alcohol copolymer graft butyl methacrylate; the grafting degree of the ethylene-vinyl alcohol copolymer graft is preferably 1-3%, and can be specifically 1%, 1.2%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7% or 3%; the melt index of the ethylene-vinyl alcohol copolymer graft under the condition of 190°C and 2.16 kg is preferably 2-4 g / 10 min, and can be 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.

[0075] In the composite pipe provided by the present application, in the intermediate layer material of the pipe, the mass ratio of the compatibilizer to ethylene-vinyl alcohol copolymer is preferably (2-4):100, and can be 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.

[0076] In the composite pipe provided by the present application, in the intermediate layer material of the pipe, the antioxidant is preferably one or more of N,N'-1,6-hexylenebis[3,5-bis(1,1-dimethylethyl)-4-hydroxybenzene propionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, bis[3,5-bis-(1,1-dimethylethyl)-4-hydroxy-] benzene propionic acid thiodiglycol ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris(2,4-di-tert-butylphenyl) phosphite, bis(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, tetra-(dibutyl hydroxyhydrocinnamic acid) pentaerythritol ester and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide.

[0077] In the composite pipe provided by the present application, the mass ratio of the antioxidant to the ethylene-vinyl alcohol copolymer in the pipe intermediate material is preferably (0.1-1):100, and can be 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.

[0078] In the composite pipe provided by the present application, the sensitizer in the pipe intermediate material is preferably one or more of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, 1,4-bis(diallylisocyanate)methylbenzene, m-phenylene bismaleimide, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

[0079] In the composite pipe provided by the present application, the mass ratio of the sensitizer to the ethylene-vinyl alcohol copolymer in the pipe intermediate material is preferably (0.5-2):100, and can be 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.

[0080] In the composite pipe provided by the present application, the pipe intermediate material is preferably prepared by melt blending and extruding the ethylene-vinyl alcohol copolymer, modified composite carbon material, compatibilizer, antioxidant and sensitizer in an extruder, and then granulating and drying. The temperature of the melt blending is preferably 170-190°C, and can be specifically 170°C, 175°C, 180°C, 185°C or 190°C; the temperature of the extruding is preferably 160-180°C, and can be specifically 160°C, 165°C, 170°C, 175°C or 180°C; and the temperature of the drying is preferably 60-80°C, and can be specifically 60°C, 65°C, 70°C, 75°C or 80°C.

[0081] In the composite pipe provided by the application, the temperature of the three-layer co-extrusion is preferably 170-190 DEG C, and can be specifically 170 DEG C, 175 DEG C, 180 DEG C, 185 DEG C or 190 DEG C; the electric field intensity of the annular pulse electric field treatment is preferably 10-14 kV / mm, and can be specifically 10 kV / mm, 10.5 kV / mm, 11 kV / mm, 11.5 kV / mm, 12 kV / mm, 12.5 kV / mm, 13 kV / mm, 13.5 kV / mm or 14 kV / mm; the pulse width of the annular pulse electric field treatment is preferably 0.5-1 mu s, and can be specifically 0.5 mu s, 0.55 mu s, 0.6 mu s, 0.65 mu s, 0.7 mu s, 0.75 mu s, 0.8 mu s, 0.85 mu s, 0.9 mu s, 0.95 mu s or 1 mu s; the pulse frequency of the annular pulse electric field treatment is preferably 500-1000 Hz, and can be specifically 500 Hz, 550 Hz, 600 Hz, 650 Hz, 700 Hz, 750 Hz, 800 Hz, 850 Hz, 900 Hz, 950 Hz or 1000 Hz; the irradiation dose of the electron beam radiation cross-linking is preferably 80-140 kGy, and can be 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.

[0082] In the composite pipe provided by the application, the thickness of the inner layer of the pipe is preferably 0.8-1.5 mm, and can be specifically 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 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 0.05-0.15 mm, and can be specifically 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm; the thickness of the outer layer of the pipe is preferably 0.8-1.5 mm, and can be specifically 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 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.

[0083] The application further provides a preparation method of the high-thermal-conductivity composite pipe described in the above technical solutions, comprising the following steps:

[0084] The inner layer material of the pipe, the intermediate layer material of the pipe and the outer layer material of the pipe are added into the hopper of the three-layer co-extrusion pipe extruder for three-layer co-extrusion, and a ring-shaped pulse electric field is applied at the die of the extruder during the extrusion process to obtain the three-layer co-extrusion pipe.

[0085] The three-layer co-extrusion pipe is subjected to electron beam radiation crosslinking to obtain the high-thermal-conductivity composite pipe.

[0086] In the preparation method provided in the application, the modified complex carbon material in the inner layer material of the pipe, the intermediate layer material of the pipe and the outer layer material of the pipe is preferably prepared according to the following steps:

[0087] The carbon black, the micro-nano carbon mixture, the surface modifier and the catalyst are mixed and reacted in a solvent, and then subjected to solid-liquid separation, washing and drying to obtain the modified complex carbon material.

[0088] In the preparation step of the modified complex carbon material provided in the application, the relevant information and the amount of each raw material are introduced in the foregoing, and will not be repeated here.

[0089] In the preparation step of the modified complex carbon material provided in the application, the specific process of the mixing reaction preferably comprises: first mixing the carbon black with the solvent, and then mixing the micro-nano carbon mixture, the surface modifier and the catalyst, and then reacting under stirring. The mixing of the carbon black and the solvent is preferably ultrasonic mixing, and the ultrasonic mixing time is preferably 20-40 min, specifically 20 min, 25 min, 30 min, 35 min or 40 min. The mixing of the micro-nano carbon mixture, the surface modifier and the catalyst is preferably ultrasonic mixing, and the ultrasonic mixing time is preferably 20-40 min, specifically 20 min, 25 min, 30 min, 35 min or 40 min. The reaction temperature is preferably 30-50℃, specifically 30℃, 35℃, 40℃, 45℃ or 50℃. The reaction time is preferably 4-6h, specifically 4h, 4.5h, 5h, 5.5h or 6h.

[0090] In the preparation step of the modified complex carbon material provided in the application, the solid-liquid separation is preferably by suction filtration, the washing is preferably by multiple water washing, and the drying temperature is preferably 60-80℃, specifically 60℃, 65℃, 70℃, 75℃ or 80℃.

[0091] In the preparation method provided in the application, the inner layer material of the pipe is preferably prepared according to the following steps:

[0092] The high-density polyethylene, modified compound carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer are added into an extruder for melt blending and extrusion, extrusion granulation, drying to obtain the pipe inner layer material.

[0093] In the pipe inner layer material preparation step, the related information and the amount of each raw material are introduced above, which will not be repeated here. Each raw material is preferably premixed uniformly before being added into the extruder. The extruder is preferably a double-screw extruder. The screw rotation speed of the extruder is preferably 150-200 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm. The temperature of the melt blending is preferably 170-190°C, specifically 170°C, 175°C, 180°C, 185°C or 190°C. The temperature of the extrusion is preferably 160-180°C, specifically 160°C, 165°C, 170°C, 175°C or 180°C. The temperature of the drying is preferably 60-80°C, specifically 60°C, 65°C, 70°C, 75°C or 80°C.

[0094] In the preparation method, the pipe intermediate layer material is preferably prepared according to the following steps:

[0095] The ethylene-vinyl alcohol copolymer, modified compound carbon material, compatibilizer, antioxidant and sensitizer are added into an extruder for melt blending and extrusion, extrusion granulation, drying to obtain the pipe intermediate layer material.

[0096] In the pipe intermediate layer material preparation step, the related information and the amount of each raw material are introduced above, which will not be repeated here. Each raw material is preferably premixed uniformly before being added into the extruder. The extruder is preferably a double-screw extruder. The screw rotation speed of the extruder is preferably 150-200 rpm, specifically 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm. The temperature of the melt blending is preferably 170-190°C, specifically 170°C, 175°C, 180°C, 185°C or 190°C. The temperature of the extrusion is preferably 160-180°C, specifically 160°C, 165°C, 170°C, 175°C or 180°C. The temperature of the drying is preferably 60-80°C, specifically 60°C, 65°C, 70°C, 75°C or 80°C.

[0097] In the preparation method, the pipe outer layer material can be prepared according to the pipe inner layer material, which will not be repeated here.

[0098] In the preparation method provided by the application, the processing temperature of the three-layer co-extrusion pipe machine is preferably 170-190 DEG C, and can be specifically 170 DEG C, 175 DEG C, 180 DEG C, 185 DEG C or 190 DEG C; the screw rotation speed of the three-layer co-extrusion pipe machine is preferably 100-150 r / min, and can be specifically 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min or 200 r / min.

[0099] In the preparation method provided by the application, the electric field intensity of the annular pulse electric field is preferably 10-14 kV / mm, and can be specifically 10 kV / mm, 10.5 kV / mm, 11 kV / mm, 11.5 kV / mm, 12 kV / mm, 12.5 kV / mm, 13 kV / mm, 13.5 kV / mm or 14 kV / mm; the pulse width of the annular pulse electric field is preferably 0.5-1 mu s, and can be specifically 0.5 mu s, 0.55 mu s, 0.6 mu s, 0.65 mu s, 0.7 mu s, 0.75 mu s, 0.8 mu s, 0.85 mu s, 0.9 mu s, 0.95 mu s or 1 mu s; the pulse frequency of the annular pulse electric field is preferably 500-1000 Hz, and can be specifically 500 Hz, 550 Hz, 600 Hz, 650 Hz, 700 Hz, 750 Hz, 800 Hz, 850 Hz, 900 Hz, 950 Hz or 1000 Hz.

[0100] In the preparation method provided by the application, the irradiation dose of the electron beam radiation crosslinking is preferably 80-140 kGy, and can be 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.

[0101] The above technical solution provided by the application at least includes the following key points and advantages:

[0102] (1) Carbon black is used as the main body, and different dimension, different structure and different particle size of the heat-conducting carbon material are compounded, a more perfect heat-conducting network is formed through the complementary effect of shape and size, the use content of the heat-conducting filler is reduced, the mechanical property is improved, and the preparation cost is reduced.

[0103] (2) The carbon black multi-component grafting is formed through the composite modification, the different dimension of the carbon material is connected through the bonding effect, which is more conducive to the construction of the effective heat-conducting path, and the compatibility with the polyethylene matrix is improved.

[0104] (3) Using the pulsed electric field emission device, the electric field strength is improved, the deflection time of the carbon material is shortened, the ordered deflection of the carbon material is realized, and the radial thermal conductivity is significantly improved; meanwhile, the melt finger regulator can reduce the melt viscosity, reduce the deflection resistance of the carbon material, and promote the formation of the ordered structure.

[0105] (4) Using high-energy electron beams for radiation crosslinking treatment, a three-dimensional network structure is formed, the heat resistance and other properties of the composite pipe are improved, and the formation of the heat conduction network is promoted, further improving the thermal conductivity of the pipe.

[0106] (5) Using carbon material compounding modification, ordered structure deflection construction, and the introduction of crosslinking network and other technical means, the thermal conductivity of the composite pipe is improved, and the comprehensive performance such as mechanical property and heat resistance is improved.

[0107] (6) The high-thermal-conductivity composite pipe prepared has high application value, has perfect heat conduction path, has certain ordered structure, has high radial thermal conductivity, and has excellent comprehensive performance, and can be applied to the field of floor heating.

[0108] (7) The preparation method has a relatively simple process, is safe and environmentally friendly, has high production efficiency, and can be mass-produced.

[0109] For a clearer understanding, the following examples and comparative examples are described in detail.

[0110] In the following examples and comparative examples of the present application, the melt index is the melt index under the condition of 190 DEG C and 2.16 kg.

[0111] In the following examples and comparative examples of the present application, the specific evaluation methods of the tensile property, the thermal conductivity and the heat resistance are as follows:

[0112] (1) Tensile property: the granulated thermal conductivity layer material is molded into a sheet of 1 mm under the condition of 180 DEG C and 10 MPa for 10 min, and then cut into a dumbbell type of 20 mm*4 mm*1 mm, and then measured by a universal tensile testing machine according to ASTM D638-2014, the tensile speed is 50 mm / min, 5 groups are measured in parallel, and the average value of 5 groups of data is taken as the result.

[0113] (2) Thermal conductivity: the pipe is cut open, the curved surface of the pipe is pressed into a sheet at 175 DEG C, and then a circular flat sample with a diameter of 3 cm is prepared, according to the standard of ASTM D5470-2012, the thermal conductivity of the material is tested by using a thermal conductivity instrument at 25 DEG C, and the average value of the test data of five samples is taken as the final result.

[0114] (3) Heat resistance: The pipe material was cut open, and the curved surface of the pipe was pressed into a sheet at 175°C, and then a square plate sample with a length and width of 1 cm was prepared. A Vicat softening temperature tester was used to test the Vicat softening temperature of the material, and the final result was the average of the data measured from five samples.

[0115] Example 1

[0116] First, 100 parts by weight of carbon black with an average particle size of 30 nm and a DBP absorption value of 250 mL / 100 g (specific surface area of 150 m 2 / g) were placed in 500 parts by weight of a methanol solvent, and after ultrasonic treatment for 20 min, 150 parts by weight of diethylenetriamine, 1 part by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, and 15 parts by weight of a micro-nano carbon mixture (a mixture of single-layer graphene (thickness 0.3 nm) and spherical micron carbon powder (particle size 1 μm) with a mass ratio of 1:1) were added. Ultrasonic treatment was continued for 20 min, followed by stirring at 30°C for 4 h, and filtration with a suction filter, and after washing with deionized water several times, the obtained solid was dried at 60°C to obtain a modified composite carbon material with a grafted structure.

[0117] 100 parts by weight of high-density polyethylene with a density of 0.940 g / cm 3 and a melt index of 3.0 g / 10 min, 10 parts by weight of linear low-density polyethylene with a density of 0.910 g / cm 3 and a melt index of 3.0 g / 10 min, 6 parts by weight of the modified composite carbon material described above, 2 parts by weight of polyethylene grafted succinic anhydride with a grafting degree of 1% and a number average molecular weight of 200,000, 0.5 parts by weight of n-hexyl-substituted oxamide, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl bis-stearamide, 0.1 parts by weight of a melt index modifier CYD-P214, 0.1 parts by weight of di[3,5-di-(1,1-dimethyl ethyl)-4-hydroxy-]benzene propanoic acid thiodiglycol ester, and 0.5 parts by weight of 1,3,5-tris(2-methylallyl)-1,3,5-triazine-2,4,6-trione, were mixed well in a high-speed mixer, and then melt blended in a twin-screw extruder, with the blending temperature set to 170°C, the extrusion temperature set to 160°C, and the screw extrusion speed set to 150 rpm. The composite material was then dried at 60°C to obtain an inner-outer layer special material.

[0118] Take 100 parts by weight of ethylene content of 25 wt% of melt index of 2.0 g / 10 min of ethylene-vinyl alcohol copolymer, 3 parts by weight of the above-mentioned modified composite carbon material, 2 parts by weight of the grafted degree of 1% of the melt index of 2.0 g / 10 min of ethylene-vinyl alcohol copolymer grafted succinic anhydride, 0.1 parts by weight of di[3,5-di-(1,1-dimethyl ethyl)-4-hydroxy-]benzene propionic acid thiodiglycol ester and 0.5 parts by weight of 1,3,5-tris(2-methyl allyl)-1,3,5-triazine-2,4,6-trione, after the material is mixed in a high-speed mixer, melt blending in a twin-screw extruder, the blending temperature is set to 170°C, the extrusion temperature is set to 160°C, and the screw extrusion speed is 150 rpm / min, then the composite material is dried at 60°C, and the middle layer special material is obtained.

[0119] The above-mentioned inner and outer layer special materials and the middle layer special material are respectively put into the hopper of the three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 170°C, the screw extrusion speed is 100 rpm / min, the thickness of the middle oxygen barrier layer is controlled to be 0.08 mm, and the thickness of the inner and outer layers is controlled to be 1.0 mm. During the extrusion process, the melt is deflected by the annular pulse electric field device at the die, the electric field strength is 10 kV / mm, the pulse width is 0.5 μs, and the frequency is 500 Hz. To realize the deflection orientation of the multi-dimensional carbon material along the radial direction, and obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is subjected to electron beam crosslinking device, to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promote the formation of the heat conduction network, and effectively improve the comprehensive performance such as heat resistance of the composite pipe, and the irradiation dose is 80 KGy, and finally a high-thermal-conductivity composite pipe is obtained.

[0120] After testing, the tensile strength of the heat conduction layer granules is 28.4 MPa, the elongation at break is 632%, the thermal conductivity of the composite pipe is 0.98 W / (m·k), and the Vicat softening temperature is 132.4°C.

[0121] Example 2

[0122] First, take 100 parts by weight of DBP absorption value of 258 mL / 100 g of carbon black with an average particle size of 32 nm (specific surface area of 165 m 2 / g), and it was placed in 525 parts by weight of anhydrous ethanol, and after ultrasonic treatment for 25 min, 175 parts by weight of triethylenetetramine, 1.2 parts by weight of triethylenetetramine, 18 parts by weight of micro-nano carbon mixture (the mass ratio of multi-walled carbon nanotubes (outer diameter 8 nm) and artificial graphite (thickness 5 μm) is 1.2:1) were added. Continue ultrasonic treatment for 25 min, then stir at 35°C for 4.5 h, and filter with a suction filter, and after washing with deionized water for several times, the obtained solid was dried at 65°C to obtain a modified composite carbon material with a grafted structure.

[0123] Take 100 parts by weight of high-density polyethylene with a density of 0.945 g / cm 3 and a melt index of 3.8 g / 10 min, 12 parts by weight of low-density polyethylene with a density of 0.915 g / cm 3 and a melt index of 3.5 g / 10 min, 8 parts by weight of the modified composite carbon material described above, 2.5 parts by weight of polyethylene grafted maleic anhydride with a grafting degree of 1.5% and a number average molecular weight of 220,000, 0.8 parts by weight of cyclohexyl-substituted oxamide, 0.6 parts by weight of calcium stearate, 0.8 parts by weight of erucamide, 0.2 parts by weight of melt index modifier CYD-P214, 0.3 parts by weight of N,N'-1,6-hexylenebis[3,5-bis(1,1-dimethylethyl)-4-hydroxybenzene propionamide], and 0.9 parts by weight of 1,4-bis(diallylisocyanate)methylbenzene, After the materials are mixed well in a high-speed mixer, melt blend in a twin-screw extruder, the blend temperature is set to 175°C, the extrusion temperature is set to 165°C, and the screw extrusion speed is 165 rpm / min, then the composite material is dried at 65°C to obtain an inner and outer layer special material.

[0124] Take 100 parts by weight of ethylene-vinyl alcohol copolymer with an ethylene content of 28 wt% and a melt index of 2.5 g / 10 min, 3.5 parts by weight of the modified composite carbon material described above, 2.5 parts by weight of ethylene-vinyl alcohol copolymer grafted citraconic anhydride with a grafting degree of 1.5% and a melt index of 2.5 g / 10 min, 0.3 parts by weight of N,N'-1,6-hexylenebis[3,5-bis(1,1-dimethylethyl)-4-hydroxybenzene propionamide], and 0.9 parts by weight of 1,4-bis(diallylisocyanate)methylbenzene, After the materials are mixed well in a high-speed mixer, melt blend in a twin-screw extruder, the blend temperature is set to 175°C, the extrusion temperature is set to 165°C, and the screw extrusion speed is 165 rpm / min, then the composite material is dried at 65°C to obtain a middle layer special material.

[0125] The inner and outer layer special material and the middle layer special material are respectively put into the hopper of the three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 175℃, the screw extrusion speed is 115 revolutions / min, the thickness of the middle oxygen barrier layer is controlled to 0.09mm, and the thickness of the inner and outer layers is controlled to 1.05mm. In the extrusion process, the melt is deflected at the die port by the annular pulse electric field device, the electric field strength is 11kV / mm, the pulse width is 0.7μs, and the frequency is 650Hz. The deflection orientation of the multi-dimensional carbon material in the radial direction is realized to obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is subjected to electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, which further promotes the formation of the heat conduction network and effectively improves the comprehensive performance such as heat resistance of the composite pipe, and the irradiation dose is 98KGy, and finally the high-thermal-conductivity composite pipe is obtained.

[0126] After testing, the tensile strength of the heat conduction layer granules is 28.9MPa, the elongation at break is 601%, the thermal conductivity of the composite pipe is 1.22W / (m·k), and the Vicat softening temperature is 133.2℃.

[0127] Example 3

[0128] First, 100 parts by weight of carbon black with an average particle size of 35nm and a DBP absorption value of 266mL / 100g (specific surface area of 190m 2 / g) is placed in 550 parts by weight of dimethylformamide, ultrasonic treatment is carried out for 30min, then 200 parts by weight of tetraethylenepentamine, 1.5 parts by weight of N-hydroxysuccinimide, and 20 parts by weight of micro-nano carbon mixture (mass ratio of graphene oxide (thickness 8nm), single-walled carbon nanotube (outer diameter 2nm), natural flake graphite (thickness 5μm) and spherical graphite (particle size 5μm) is 1.5:1.5:1:1) are added. Continue ultrasonic treatment for 30min, then stir at 40℃ for 5h, and filter with a suction filter, then wash with deionized water several times, then dry the obtained solid at 70℃ to obtain a modified composite carbon material with a grafted structure.

[0129] Take 100 parts by weight of high-density polyethylene with a density of 0.950g / cm 3 and a melt index of 4.7g / 10min, 15 parts by weight of low-density polyethylene with a density of 0.925g / cm 3The inner and outer layer special material and the middle layer special material are respectively put into the hopper of a three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 180°C, the screw extrusion speed is 130 rpm, the thickness of the middle oxygen barrier layer is controlled to 0.10 mm, and the thickness of the inner and outer layers is controlled to 1.1 mm. During the extrusion process, the melt is deflected at the die by a ring-shaped pulsed electric field device, the electric field strength is 12 kV / mm, the pulse width is 0.8 μs, and the frequency is 800 Hz. The multi-dimensional carbon material is oriented in the radial direction to obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is then subjected to an electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promoting the formation of a heat conduction network and effectively improving the comprehensive performance of the composite pipe, such as heat resistance, and the irradiation dose is 115 KGy. Finally, a high-thermal-conductivity composite pipe is obtained.

[0130] The inner and outer layer special material and the middle layer special material are respectively put into the hopper of a three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 180°C, the screw extrusion speed is 130 rpm, the thickness of the middle oxygen barrier layer is controlled to 0.10 mm, and the thickness of the inner and outer layers is controlled to 1.1 mm. During the extrusion process, the melt is deflected at the die by a ring-shaped pulsed electric field device, the electric field strength is 12 kV / mm, the pulse width is 0.8 μs, and the frequency is 800 Hz. The multi-dimensional carbon material is oriented in the radial direction to obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is then subjected to an electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promoting the formation of a heat conduction network and effectively improving the comprehensive performance of the composite pipe, such as heat resistance, and the irradiation dose is 115 KGy. Finally, a high-thermal-conductivity composite pipe is obtained.

[0131] The inner and outer layer special material and the middle layer special material are respectively put into the hopper of a three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 180°C, the screw extrusion speed is 130 rpm, the thickness of the middle oxygen barrier layer is controlled to 0.10 mm, and the thickness of the inner and outer layers is controlled to 1.1 mm. During the extrusion process, the melt is deflected at the die by a ring-shaped pulsed electric field device, the electric field strength is 12 kV / mm, the pulse width is 0.8 μs, and the frequency is 800 Hz. The multi-dimensional carbon material is oriented in the radial direction to obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is then subjected to an electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promoting the formation of a heat conduction network and effectively improving the comprehensive performance of the composite pipe, such as heat resistance, and the irradiation dose is 115 KGy. Finally, a high-thermal-conductivity composite pipe is obtained.

[0132] After testing, the tensile strength of the heat conduction layer granules is 29.2 MPa, the elongation at break is 551%, the thermal conductivity of the composite pipe is 1.68 W / (m·k), and the Vicat softening temperature is 133.9°C.

[0133] Example 4

[0134] First, 100 parts by weight of carbon black with an average particle size of 38 nm and a DBP absorption value of 272 mL / 100 g (specific surface area of 200 m 2 / g) was placed in 575 parts by weight of anhydrous ethanol, and after ultrasonic treatment for 35 min, 235 parts by weight of pentaethylenehexamine, 1.7 parts by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 22 parts by weight of a micro-nano carbon mixture (a mixture of reduced graphene oxide (thickness 8 nm), graphyne (thickness 20 nm), silicon carbide (particle size 3 μm), and needle-shaped micron carbon powder (diameter 5 μm) in a mass ratio of 1.8:1.8:1:1) were added. Ultrasonic treatment was continued for 35 min, after which stirring was carried out at 45°C for 5.5 h, and the resulting solid was filtered using a suction filter and washed with deionized water several times, and then the resulting solid was dried at 80°C to obtain a modified composite carbon material with a grafted structure.

[0135] Take 100 parts by weight of high-density polyethylene with a density of 0.955 g / cm 3 and a melt index of 5.4 g / 10 min, 8 parts by weight of linear low-density polyethylene with a density of 0.930 g / cm 3 and a melt index of 4.5 g / 10 min, 8 parts by weight of ethylene-octene copolymer with a density of 0.910 g / cm 3 and a melt index of 5.0 g / 10 min, 13 parts by weight of the modified composite carbon material described above, 3.5 parts by weight of polyethylene grafted with ethylene methyl acrylate with a number average molecular weight of 280,000 and a grafting degree of 2.5%, 1.5 parts by weight of benzene di-p-methylbenzyl sorbitol, 0.8 parts by weight of barium stearate, 1.7 parts by weight of glyceryl stearate, 0.4 parts by weight of melt index modifier CYD-P214, 0.8 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, and 1.5 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, and the materials were thoroughly mixed in a high-speed mixer, then melt blended in a twin-screw extruder, and then extruded and pelletized, with the blending temperature set to 185°C, the extrusion temperature set to 175°C, and the screw extrusion speed set to 185 rpm, and then the composite material was dried at 75°C to obtain an inner-outer layer special material.

[0136] Take 100 parts by weight of ethylene content of 30 wt% of melt index of 3.5 g / 10 min of ethylene-vinyl alcohol copolymer, 4.5 parts by weight of the above modified composite carbon material, 3.5 parts by weight of the melt index of 3.5 g / 10 min of ethylene-vinyl alcohol copolymer grafted with methyl methacrylate with a grafting degree of 2.5%, 0.8 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite and 1.5 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, mix the materials in a high-speed mixer, then melt blend in a twin-screw extruder, set the blending temperature to 185°C, the extrusion temperature to 175°C, and the screw extrusion speed to 185 rpm, then dry the composite material at 75°C to obtain the middle layer special material.

[0137] Put the above-mentioned inner and outer layer special materials and the middle layer special material into the hopper of a three-layer co-extrusion pipe extruder, set the processing temperature of the extruder to 185°C, the screw extrusion speed to 140 rpm, the thickness of the middle oxygen barrier layer to 0.11 mm, and the thickness of the inner and outer layers to 1.15 mm. During the extrusion process, the melt is deflected by the annular pulse electric field device at the die, with an electric field strength of 13 kV / mm, a pulse width of 0.9 μs, and a frequency of 900 Hz. This achieves the deflection orientation of the multi-dimensional carbon material in the radial direction, obtaining a quasi-ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The prepared pipe is then subjected to an electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promoting the formation of the thermal conduction network and effectively improving the comprehensive performance of the composite pipe, such as heat resistance, with an irradiation dose of 130 KGy, finally obtaining a high-thermal-conductivity composite pipe.

[0138] After testing, the tensile strength of the thermal conductivity layer granules was 29.8 MPa, the elongation at break was 508%, the thermal conductivity of the composite pipe was 2.01 W / (m·k), and the Vicat softening temperature was 134.3°C.

[0139] Example 5

[0140] First, take 100 parts by weight of carbon black with an average particle size of 40 nm and a DBP absorption value of 280 mL / 100 g (specific surface area of 210 m 2 / g), and placed in 300 parts by weight of anhydrous ethanol and 300 parts by weight of a mixed solvent 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, 1 part by weight of N-hydroxysuccinimide, 25 parts by weight of micro-nano carbon mixture (mass ratio of multi-layer graphene (thickness 5 nm), multi-walled carbon nanotube (outer diameter 8 nm), graphyne (thickness 20 nm), pyrolytic graphite (thickness 4 μm), carbon fiber powder (diameter 5 μm), spherical micron carbon powder (particle size 3 μm) is 2:2:2:1:1:1) were added. Continue to ultrasonic treatment for 40 min, then stir at 50℃ for 6h, and filter with a suction filter, after washing with deionized water for several times, the obtained solid is dried at 80℃, to obtain a modified composite carbon material with a grafted structure.

[0141] Take 100 parts by weight of high-density polyethylene with a density of 0.960 g / cm 3 and a melt index of 6.0 g / 10 min, 10 parts by weight of low-density polyethylene with a density of 0.925 g / cm 3 and a melt index of 5.0 g / 10 min, 10 parts by weight of metallocene medium-density polyethylene with a density of 0.935 g / cm 3 and a melt index of 6.0 g / 10 min, 16 parts by weight of the modified composite carbon material described above, 2 parts by weight of polyethylene grafted itaconic anhydride with a grafting degree of 3% and a number average molecular weight of 300,000, 2 parts by weight of polyethylene grafted methyl methacrylate with a grafting degree of 3% and a number average molecular weight of 300,000, 1 part by weight of poly(4-methoxy-4'-acryloyloxybenzoic acid phenyl ester), 1 part by weight of di(p-ethyl dibenzylidene 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, 0.5 parts by weight of melt index modifier CYD-P214, 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-dimethyl ethyl)-4-hydroxy-]benzene propionic acid thiodiglycol ester, 1 part by weight of 1,4-bis(diallyl isocyanate) methylbenzene, and 1 part by weight of trimethylolpropane trimethacrylate, after mixing the materials well in a high-speed mixer, pelletizing in a twin-screw extruder, the blending temperature is set to 190℃, the extrusion temperature is set to 180℃, and the screw extrusion speed is 200 rpm / min, then the composite material is dried at 80℃, to obtain an inner-outer layer special material.

[0142] Take 100 parts by weight of ethylene content of 35 wt% of melt index of 4.0 g / 10 min of ethylene-vinyl alcohol copolymer, 5 parts by weight of the above-mentioned modified composite carbon material, 2 parts by weight of the melt index of 4.0 g / 10 min of ethylene-vinyl alcohol copolymer grafted maleic anhydride with a grafting degree of 3%, 2 parts by weight of ethylene-vinyl alcohol copolymer grafted with glycidyl methacrylate with a grafting degree of 3%, 0.5 parts by weight of bis(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide, 0.5 parts by weight of bis[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]benzene propionic acid thiodiglycol ester, 1 part by weight of 1,4-bis(diallyl isocyanate) methylbenzene and 1 part by weight of trimethylolpropane trimethacrylate, after the material is mixed in a high-speed mixer, melt blend in a twin-screw extruder, the blending temperature is set to 190°C, the extrusion temperature is set to 180°C, the screw extrusion speed is 200 rpm / min, then the composite material is dried at 80°C, and the middle layer special material is obtained.

[0143] Put the above-mentioned inner and outer layer special materials and the middle layer special material into the hopper of the three-layer co-extrusion pipe extruder respectively, set the processing temperature of the extruder to 190°C, the screw extrusion speed to 150 rpm / min, the thickness of the middle oxygen barrier layer to 0.12 mm, and the thickness of the inner and outer layers to 1.2 mm. During the extrusion process, the melt is deflected by the annular pulse electric field device at the die, the electric field strength is 14 kV / mm, the pulse width is 1 μs, and the frequency is 1000 Hz. To achieve the deflection orientation of the multi-dimensional carbon material in the radial direction, obtain an ordered structure, and thus improve the radial thermal conductivity of the composite pipe. The prepared pipe is then subjected to electron beam crosslinking device to initiate crosslinking of the composite pipe to form a three-dimensional network structure, further promoting the formation of the heat conduction network, and effectively improving the comprehensive performance of the composite pipe, such as heat resistance, the irradiation dose is 140 KGy, and finally a high-thermal-conductivity composite pipe is obtained.

[0144] After testing, the tensile strength of the heat conduction layer granules is 29.2 MPa, the elongation at break is 472%, the thermal conductivity of the composite pipe is 2.39 W / (m·k), and the Vicat softening temperature is 134.8°C.

[0145] Comparative Example 1

[0146] First, take 6 parts by weight of carbon black with an average particle size of 30 nm and a DBP absorption value of 250 mL / 100 g (specific surface area of 150 m 2 / g), take 100 parts by weight of high-density polyethylene with a density of 0.940 g / cm 3 / min, 10 parts by weight of low-density polyethylene with a density of 0.910 g / cm 3linear low density polyethylene with a melt index of 3.0 g / 10 min, 0.5 parts by weight of n-hexyl-substituted oxamide, 0.5 parts by weight of zinc stearate, and 0.5 parts by weight of vinyl bis-stearamide. After the materials are thoroughly mixed in a high-speed mixer, melt blending is performed in a twin-screw extruder, the blending temperature is set to 170°C, the extrusion temperature is set to 160°C, the screw extrusion speed is 150 rpm, and then the composite material is dried at 60°C to obtain the inner and outer layer special material.

[0147] Take 100 parts by weight of ethylene-vinyl alcohol copolymer with an ethylene content of 25 wt% and a melt index of 2.0 g / 10 min, 3 parts by weight of carbon black with an average particle size of 30 nm and a DBP absorption value of 250 mL / 100 g (specific surface area of 150 m 2 / g), and thoroughly mix the materials in a high-speed mixer, melt blend in a twin-screw extruder, and then extrude and granulate, the blending temperature is set to 170°C, the extrusion temperature is set to 160°C, the screw extrusion speed is 150 rpm, and then the composite material is dried at 60°C to obtain the middle layer special material.

[0148] The inner and outer layer special materials and the middle layer special material are respectively placed into the hopper of a three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 170°C, the screw extrusion speed is 100 rpm, the thickness of the middle oxygen barrier layer is controlled to be 0.08 mm, and the thickness of the inner and outer layers is controlled to be 1 mm. The final heat-conducting composite pipe material is obtained.

[0149] After testing, the tensile strength of the heat-conducting layer granules is 25.5 MPa, the elongation at break is 502%, the thermal conductivity of the composite pipe material is 0.38 W / (m·k), and the Vicat softening temperature is 118.7°C.

[0150] As can be seen from the comparison between Comparative Example 1 and Example 1, after the compounding modification treatment, the pulse electric field deflection treatment, and the crosslinking irradiation treatment, the mechanical properties of the heat-conducting layer granules, the thermal conductivity of the pipe material, and the Vicat softening temperature are all significantly improved.

[0151] Comparative Example 2

[0152] First, take 100 parts by weight of carbon black with an average particle size of 30 nm and a DBP absorption value of 250 mL / 100 g (specific surface area of 150 m 2 / g), and then placed in 500 parts by weight of a methanol solvent, and after ultrasonic treatment for 20 min, 150 parts by weight of diethylenetriamine, 1 part by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, and 15 parts by weight of micro-nano carbon mixture (a mixture of single-layer graphene (thickness 0.3 nm) and spherical micron carbon powder (particle size 1 μm) at a mass ratio of 1:1) were added. Ultrasonic treatment was continued for 20 min, after which stirring was performed at 30°C for 4 h, and the resulting solid was filtered using a suction filter, washed several times with deionized water, and then dried at 60°C to obtain a modified composite carbon material having a grafted structure.

[0153] Take 100 parts by weight of high-density polyethylene with a density of 0.940 g / cm 3 and a melt index of 3.0 g / 10 min, 10 parts by weight of linear low-density polyethylene with a density of 0.910 g / cm 3 and a melt index of 3.0 g / 10 min, 6 parts by weight of the modified composite carbon material described above, 2 parts by weight of polyethylene grafted succinic anhydride with a number average molecular weight of 200,000 and a grafting degree of 1%, 0.5 parts by weight of n-hexyl-substituted oxamide, 0.5 parts by weight of zinc stearate, 0.5 parts by weight of vinyl bis-stearamide, and 0.1 parts by weight of melt index modifier CYD-P214. After the materials were thoroughly mixed in a high-speed mixer, they were melt blended in a twin-screw extruder and then extruded and pelletized, with the blending temperature set to 170°C, the extrusion temperature set to 160°C, and the screw extrusion speed set to 150 rpm. The composite material was then dried at 60°C to obtain an inner-outer layer special material.

[0154] Take 100 parts by weight of ethylene-vinyl alcohol copolymer with an ethylene content of 25 wt% and a melt index of 2.0 g / 10 min, 3 parts by weight of the modified composite carbon material described above, and 2 parts by weight of ethylene-vinyl alcohol copolymer grafted succinic anhydride with a melt index of 2.0 g / 10 min and a grafting degree of 1%. After the materials were thoroughly mixed in a high-speed mixer, they were melt blended in a twin-screw extruder and then extruded and pelletized, with the blending temperature set to 170°C, the extrusion temperature set to 160°C, and the screw extrusion speed set to 150 rpm. The composite material was then dried at 60°C to obtain a middle layer special material.

[0155] The inner and outer layer special material and the middle layer special material are respectively put into the hopper of the three-layer co-extrusion pipe extruder, the processing temperature of the extruder is set to 170℃, the screw extrusion speed is 100 revolutions / min, the thickness of the middle oxygen barrier layer is controlled to 0.08mm, and the thickness of the inner and outer layers is controlled to 1mm. During the extrusion process, the melt is deflected at the die port by the annular pulse electric field device, the electric field strength is 10kV / mm, the pulse width is 0.5μs, and the frequency is 500Hz. The deflection orientation of the multi-dimensional carbon material in the radial direction is realized to obtain an ordered structure, thereby improving the radial thermal conductivity of the composite pipe. The final thermal conductive composite pipe is obtained.

[0156] After testing, the tensile strength of the thermal conductive layer granules is 27.3MPa, the elongation at break is 640%, the thermal conductivity of the composite pipe is 0.89W / (m·k), and the Vicat softening temperature is 119.5℃.

[0157] It can be seen from the comparison of Comparative Example 2 and Example 1 that after the irradiation crosslinking treatment, the Vicat softening temperature of the pipe is obviously improved, the three-dimensional network structure formed further promotes the perfection of the thermal conductive network, and the thermal conductivity is improved.

[0158] Comparative Example 3

[0159] First, 100 parts by weight of carbon black with an average particle size of 30nm and a DBP absorption value of 250mL / 100g (specific surface area of 150m 2 / g) are taken, which are placed in 500 parts by weight of a methanol solvent, ultrasonic treatment is carried out for 20min, then 150 parts by weight of diethylenetriamine, 1 part by weight of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, and 15 parts by weight of a micro-nano carbon mixture (mass ratio of single-layer graphene (thickness 0.3nm) and spherical micron carbon powder (particle size 1μm) is 1:1) are added. Continue ultrasonic treatment for 20min, then stir at 30℃ for 4h, and filter with a suction filter, then wash with deionized water several times, then dry the obtained solid at 60℃ to obtain a modified composite carbon material with a grafted structure.

[0160] Take 100 parts by weight of high-density polyethylene with a density of 0.940g / cm 3 and a melt index of 3.0g / 10min, 10 parts by weight of low-density polyethylene with a density of 0.910g / cm 3The inner and outer layer special material and the middle layer special material are respectively put into the hopper of a three-layer co-extrusion pipe material extruder, the processing temperature of the extruder is set to 170°C, the screw extrusion speed is 100 r / min, the thickness of the middle oxygen barrier layer is controlled to 0.08 mm, and the thickness of the inner layer and the outer layer is controlled to 1 mm. The prepared pipe material is subjected to electron beam crosslinking device to initiate crosslinking of the composite pipe material to form a three-dimensional network structure, further promote the formation of the heat conduction network, and effectively improve the comprehensive performance such as heat resistance of the composite pipe material, and the irradiation dose is 80 KGy, and finally a high-heat-conducting composite pipe material is obtained.

[0161] Take 100 parts by weight of ethylene-vinyl alcohol copolymer containing 25wt% of ethylene, 3 parts by weight of the modified composite carbon material, 2 parts by weight of ethylene-vinyl alcohol copolymer grafted with succinic anhydride with a grafting degree of 1%, 0.1 parts by weight of di[3,5-di-(1,1-dimethyl ethyl)-4-hydroxy-]benzene propionic acid thiodiglycol ester and 0.5 parts by weight of 1,3,5-tri(2-methyl allyl)-1,3,5-triazine-2,4,6-trione, mix the materials in a high-speed mixer, melt blend in a twin-screw extruder, then extrude and granulate, the blending temperature is set to 170°C, the extrusion temperature is set to 160°C, and the screw extrusion speed is 150 r / min, then the composite material is dried at 60°C, and the middle layer special material is obtained.

[0162] The inner and outer layer special material and the middle layer special material are respectively put into the hopper of a three-layer co-extrusion pipe material extruder, the processing temperature of the extruder is set to 170°C, the screw extrusion speed is 100 r / min, the thickness of the middle oxygen barrier layer is controlled to 0.08 mm, and the thickness of the inner layer and the outer layer is controlled to 1 mm. The prepared pipe material is subjected to electron beam crosslinking device to initiate crosslinking of the composite pipe material to form a three-dimensional network structure, further promote the formation of the heat conduction network, and effectively improve the comprehensive performance such as heat resistance of the composite pipe material, and the irradiation dose is 80 KGy, and finally a high-heat-conducting composite pipe material is obtained.

[0163] Through testing, the tensile strength of the heat conduction layer granules is 28.2 MPa, the elongation at break is 629%, the thermal conductivity of the composite pipe material is 0.65 W / (m·k), and the Vicat softening temperature is 131.8°C.

[0164] It can be seen from the comparison of Comparative Example 3 and Example 1 that after the pulse electric field deflection treatment, the multi-dimensional carbon material is deflected along the radial direction, effectively improving the radial thermal conductivity of the pipe material.

[0165] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A high thermal conductivity composite pipe, characterized in that, It is made by co-extruding three layers of pipe material, pipe middle layer material and pipe outer layer material, and then treating them with an annular pulse electric field at the extruder die, followed by electron beam radiation cross-linking. The inner layer material of the pipe comprises: high-density polyethylene, modified composite carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer; The components of the intermediate layer material of the pipe include: ethylene-vinyl alcohol copolymer, modified composite carbon material, compatibilizer, antioxidant and sensitizer; The outer layer of the pipe material comprises: high-density polyethylene, modified composite carbon material, toughening agent, compatibilizer, melt index modifier, nucleating agent, dispersant, lubricant, antioxidant and sensitizer; The modified composite carbon material comprises carbon black, micro / nano carbon mixture, surface modifier, and catalyst, wherein the micro / nano carbon mixture includes nano carbon materials and micron carbon materials.

2. The high thermal conductivity composite pipe according to claim 1, characterized in that, The modified composite carbon material contains carbon black with 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 nano-carbon material in the modified composite carbon material is one or more of single-layer graphene, multi-layer graphene, graphene oxide, reduced graphene oxide, graphyne, single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. And / or, the micron-sized carbon material in the modified composite carbon material is one or more of the following: silicon carbide micro powder, natural flake graphite micro powder, artificial graphite micro powder, pyrolytic graphite micro powder, expanded graphite micro powder, spherical graphite micro powder, spherical micron-sized carbon powder, needle-shaped micron-sized carbon powder, fibrous micron-sized carbon powder, and carbon fiber powder. And / or, the surface modifier in the modified composite carbon material is one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; And / or, the catalyst in the modified composite carbon material is one or more of N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine, 1-hydroxybenzotriazole and N-hydroxysuccinimide.

3. The high thermal conductivity composite pipe according to claim 1, characterized in that, The mass ratio of carbon black, micro / nano carbon mixture, surface modifier and catalyst in the modified composite carbon material is 100:(15-25):(150-250):(1-2); the mass ratio of nano carbon material and micron carbon material in the micro / nano carbon mixture is (1-2):

1.

4. The high thermal conductivity composite pipe according to claim 1, characterized in that, The density of the high-density polyethylene in the inner and outer layers 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 and outer layers 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 and outer layers 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 melt index modifier in the inner and outer layers of the pipe is of the grade CYD-P214; And / or, the nucleating agent in the inner and outer layers of the pipe is one or more of the following: hexyl-substituted oxamide, cyclohexyl-substituted oxamide, poly(4-methoxy)-diphenoloxycarbonylphenol acrylate, poly(4-methoxy-4'-acryloyloxybenzoate), benzoimidazolinone, isoindoline, dimethylbenzyl sorbitol, di(p-ethylbenzyl)sorbitol, dichlorobenzyl sorbitol, and sodium benzoate; And / or, the dispersant in the inner and outer layers 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 and outer layers of the pipe is one or more of vinyl bis-stearamide, erucamide, oleamide, glyceryl stearate and pentaerythritol stearate; And / or, the antioxidants in the inner and outer layers of the pipe are N,N'-1,6-hexanediol di[3,5-di(1,1-dimethylethyl)-4-hydroxyphenylpropionamide], octadecyl di-T-butyl-4-hydroxyhydrocinnamate, bis[3,5-di-(1,1-dimethylethyl)-4-hydroxy-]phenylpropionate thiadiglycol ester, 1,3,5-trimethyl-2,4,6 One or more of the following: 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-(dibutylhydroxyhydrocinnamic acid) ester, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]propionylhydrazide; And / or, the sensitizer in the inner and outer layers 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.

5. The high thermal conductivity composite pipe according to claim 1, characterized in that, The mass ratio of high-density polyethylene, modified compound carbon material, toughening agent, compatibilizer, melt index regulator, nucleating agent, dispersant, lubricant, antioxidant and sensitizer in the inner layer material of the pipe is 100:(6~16):(10~20):(2~4):(0.1~0.5):(0.5~2):(0.5~1):(0.5~2):(0.1~1):(0.5~2).

6. The high thermal conductivity composite pipe according to claim 1, characterized in that, The content of repeating units corresponding to the ethylene structure in the ethylene-vinyl alcohol copolymer in the intermediate layer material of the pipe is 25-35 wt%. And / or, the compatibilizer in the intermediate layer of the pipe is one or more of the following: ethylene-vinyl alcohol copolymer grafted with succinic anhydride, ethylene-vinyl alcohol copolymer grafted with citraconic anhydride, ethylene-vinyl alcohol copolymer grafted with itaconic anhydride, ethylene-vinyl alcohol copolymer grafted with octenyl succinic anhydride, ethylene-vinyl alcohol copolymer grafted with maleic anhydride, ethylene-vinyl alcohol copolymer grafted with glycidyl methacrylate, ethylene-vinyl alcohol copolymer grafted with methyl methacrylate, ethylene-vinyl alcohol copolymer grafted with methyl methacrylate, and ethylene-vinyl alcohol copolymer grafted with butyl methacrylate. 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 high thermal conductivity composite pipe according to claim 1, characterized in that, The mass ratio of ethylene-vinyl alcohol copolymer, modified compound carbon material, compatibilizer, antioxidant and sensitizer in the intermediate layer material of the pipe is 100:(3~5):(2~4):(0.1~1):(0.5~2).

8. A method for preparing a high thermal conductivity composite pipe according to any one of claims 1 to 7, 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. During the extrusion process, an annular pulse electric field is applied at the die of the extruder to obtain a three-layer co-extruded pipe. The three-layer co-extruded pipe is cross-linked by electron beam radiation to obtain a high thermal conductivity composite pipe.

9. The preparation method according to claim 8, characterized in that, The electric field strength of the ring pulse electric field is 10–14 kV / mm, the pulse width is 0.5–1 μs, and the pulse frequency is 500–1000 Hz.

10. The preparation method according to claim 8, characterized in that, The irradiation dose for electron beam crosslinking is 80–140 kGy.