A heat-insulating pipe with strong compressive and tensile resistance

Abstract

This application relates to the technical field of the production of controlled articles, and in particular to a heat-insulating pipe with strong compressive and tensile resistance. This application discloses a heat-insulating pipe with strong compressive and tensile resistance, which includes a coaxial inner pipe and an outer pipe. A heat-insulating material is filled between the inner pipe and the outer pipe. The heat-insulating material comprises the following raw materials in parts by mass: 60-70 parts of polyethylene, 20-30 parts of recycled material, 5-10 parts of glass fiber, 2-4 parts of coupling agent, and 15-25 parts of carbon nanotube / polyethylene composite material. Among them, the carbon nanotube / polyethylene composite material comprises the following raw materials in parts by mass: 30-40 parts of polyethylene, 1-3 parts of carbon nanotube, 1-3 parts of carbon black, and 3-7 parts of maleic anhydride grafted polyethylene. This application discloses a heat-insulating pipe with strong compressive and tensile resistance. The heat-insulating pipe prepared by this application effectively improves the compressive and tensile properties of the heat-insulating pipe while maintaining good heat-insulating performance.

Description

Technical Field

[0001] This application relates to the technical field of the production of regulated products, and particularly to a heat-insulating pipe with strong compressive and tensile resistance. Background Art

[0002] In the prior art, to address the problem of insufficient compressive and tensile properties of heat-insulating pipes, the industry has generally taken some measures; common means include increasing the wall thickness of the heat-insulating pipe. Although this method can improve the compressive property to a certain extent, it will significantly increase the manufacturing cost. Another method is to add ordinary fillers such as stone powder and talcum powder. These fillers can improve the rigidity of the material to a certain extent, but the improvement effect on the overall compressive and tensile properties is limited, and it may cause a decrease in the flexibility of the material.

[0003] However, the above methods have obvious limitations. For example, increasing the wall thickness not only increases the manufacturing cost but also makes the transportation and installation of the heat-insulating pipe more difficult. Moreover, although adding ordinary fillers can partially improve the rigidity of the material, it cannot significantly improve its compressive and tensile properties. Especially under heavy loads, the heat-insulating pipe is still prone to deformation or even rupture, resulting in a decrease in the heat-insulating performance, increasing the maintenance cost and potential safety hazards.

[0004] Therefore, how to effectively improve the compressive and tensile strength of the heat-insulating pipe has become an urgent problem to be solved currently. Summary of the Invention

[0005] In view of the deficiencies of the prior art, this application provides a heat-insulating pipe with strong compressive and tensile resistance.

[0006] In the first aspect, this application provides a heat-insulating pipe with strong compressive and tensile resistance, adopting the following technical solution:

[0007] A heat-insulating pipe with strong compressive and tensile resistance includes a coaxial inner pipe and outer pipe, and a heat-insulating material is filled between the inner pipe and the outer pipe. The heat-insulating material comprises the following raw materials in parts by mass: 60 - 70 parts of polyethylene, 20 - 30 parts of recycled material, 5 - 10 parts of glass fiber, 2 - 4 parts of coupling agent, and 15 - 25 parts of carbon nanotube / polyethylene composite material;

[0008] Among them, the carbon nanotube / polyethylene composite material comprises the following raw materials in parts by mass: 30 - 40 parts of polyethylene, 1 - 3 parts of carbon nanotube, 1 - 3 parts of carbon black, and 3 - 7 parts of maleic anhydride grafted polyethylene.

[0009] By adopting the above-mentioned technical solution, the present application improves the formula of the thermal insulation material by adding a nano-carbon tube / polyethylene composite material with compressive and tensile properties. The added nano-carbon tube / polyethylene composite material is mixed with polyethylene, recycled materials, and glass fiber under the action of a coupling agent to obtain a nano-carbon tube / polyethylene composite material with compressive and tensile properties, thereby further improving the compressive and tensile properties of the thermal insulation material.

[0010] In this application, the compressive and tensile strengths and thermal insulation performance of the insulation pipe are effectively improved by adjusting the components in the insulation material and the proportions of the components.

[0011] Polyethylene (HDPE) has high mechanical strength and chemical resistance, making it suitable for high-strength insulation pipes. In addition to HDPE, low-density polyethylene (LDPE) or other types of polyethylene can also be used, but HDPE offers superior overall performance.

[0012] Glass fiber has excellent mechanical properties and can significantly increase the tensile strength of insulation pipes. In addition to glass fiber, other high-performance fibers such as carbon fiber and aramid fiber can also be used, which can improve tensile strength while maintaining a certain degree of flexibility.

[0013] Coupling agents can promote adhesion between different components and improve the consistency and durability of the overall structure.

[0014] The present application forms an insulation pipe with good compressive and tensile properties by rationally proportioning polyethylene, recycled materials, glass fibers, and carbon nanotube / polyethylene composite materials, and adding a coupling agent. High-density polyethylene as a base material provides good mechanical strength and chemical corrosion resistance; the recycled materials are pre-treated to remove impurities, ensuring the uniform distribution of the material and improving the overall quality of the composite material; the addition of glass fibers significantly improves the tensile strength of the insulation pipe, making it less likely to deform or break under heavy loads; the use of coupling agents enhances the bonding effect between different components, improves the consistency and durability of the overall structure, and the addition of carbon nanotube / polyethylene composite materials improves the compressive and tensile resistance of the insulation pipe. The technical solution of the present application not only improves the mechanical properties of the insulation pipe, but also reduces costs and simplifies the production process while ensuring the original insulation performance, and has high practical value.

[0015] Preferably, the thermal insulation material further comprises 10-20 parts by mass of a phenolic resin / carbon nanoparticle composite material.

[0016] By adopting the above technical solution, in the present application, the formula of the thermal insulation material is improved by adding the phenolic resin / carbon nanoparticle composite material with good thermal insulation performance. After the added phenolic resin / carbon nanoparticle composite material is mixed with glass fiber and carbon nanotube / polyethylene composite material under the action of a coupling agent, it is then mixed with polyethylene and recycled material to obtain a thermal insulation material with good thermal insulation performance, thereby further improving the thermal insulation performance of the thermal insulation pipe.

[0017] Preferably, the phenolic resin / carbon nanoparticle composite material comprises the following raw materials in parts by mass: 60 - 90 parts of carbon nanoparticles, 50 - 150 parts of phenolic resin, 1 - 2 parts of polyurethane, 50 - 60 parts of absolute ethanol, 5 - 10 parts of gum arabic, and 1 - 3 parts of coupling agent.

[0018] Preferably, the preparation method of the phenolic resin / carbon nanoparticle composite material comprises the following steps:

[0019] Weigh each raw material according to the formula;

[0020] Mix the phenolic resin and absolute ethanol, and add polyurethane for mixing to obtain modified phenolic resin;

[0021] Mix the modified phenolic resin, carbon nanoparticles, gum arabic, and coupling agent to obtain the phenolic resin / carbon nanoparticle composite material.

[0022] By adopting the above technical solution, since phenolic resin is a kind of thermal insulation and fireproof material with low thermal conductivity and excellent chemical stability, but its mechanical properties are poor, resulting in difficult construction. In the present application, the phenolic resin is modified by reacting it with absolute ethanol and polyurethane to obtain modified phenolic resin; the obtained modified phenolic resin is mixed with carbon nanoparticles, gum arabic, and coupling agent to obtain the phenolic resin / carbon nanoparticle composite material with thermal insulation performance, thereby further improving the thermal insulation performance of the thermal insulation pipeline.

[0023] Preferably, the preparation steps of the carbon nanotube / polyethylene composite material are as follows:

[0024] Weigh each raw material according to the formula;

[0025] Add the carbon nanotubes to the aqua regia solution for mixing, and filter to obtain modified carbon nanotubes;

[0026] Mix the modified carbon nanotubes with maleic anhydride grafted polyethylene, filter, and add polyethylene and carbon black for mixing to obtain the carbon nanotube / polyethylene composite material.

[0027] By adopting the above technical solution, in this application, the carbon nanotubes are modified to obtain modified carbon nanotubes; the modified carbon nanotubes are grafted with maleic anhydride-grafted polyethylene molecules, and the grafted modified carbon nanotubes are then mixed with polyethylene and carbon black to obtain a carbon nanotube / polyethylene composite material with compressive and tensile properties. At the same time, the prepared carbon nanotube / polyethylene composite material also has certain electrical conductivity.

[0028] Preferably, the modification treatment of the glass fiber is carried out as follows:

[0029] After mixing the coupling agent and ethanol, add the glass fiber for mixing, place it at 80-100 °C for 8-10 hours, and filter to obtain the modified glass fiber.

[0030] Preferably, the mass ratio of the coupling agent to ethanol is 1:(3-5); the mass ratio of the glass fiber to the coupling agent is (5-10):(1-2).

[0031] By adopting the above technical solution, in this application, through the modification of the glass fiber, the modified glass fiber has good compatibility, enabling the modified glass fiber to be better mixed with other raw materials to obtain a thermal insulation material with compressive and tensile properties.

[0032] Preferably, the recycled material is waste plastic particles, and the waste plastic is at least one of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene.

[0033] By adopting the above technical solution, the waste plastic particles are pretreated to remove impurities, ensuring the uniform distribution of the materials and improving the overall quality of the composite material; the recycled material can come from various sources, such as waste plastic products and industrial waste. Through high-temperature disinfection and mechanical crushing treatment, its cleanliness and fineness are ensured.

[0034] In the second aspect, this application provides a preparation method of a thermal insulation pipe with strong compressive and tensile abilities, adopting the following technical solution:

[0035] A preparation method of a thermal insulation pipe with strong compressive and tensile abilities, the preparation method comprises the following steps:

[0036] (1) Preparation of the thermal insulation material:

[0037] Weigh each raw material according to the formula;

[0038] Mix the glass fiber, coupling agent, phenolic resin / carbon nanoparticle composite material, add the carbon nanotube / polyethylene composite material for mixing; then add polyethylene and recycled material for mixing to obtain the thermal insulation material;

[0039] (2) Preparation of the thermal insulation pipe;

[0040] The thermal insulation material is pressed through a lamination molding process, and the pressed thermal insulation material is filled between the inner pipe and the outer pipe to obtain a thermal insulation pipe.

[0041] Preferably, the reaction conditions of the lamination molding process are as follows:

[0042] The reaction pressure is 5 MPa;

[0043] The reaction temperature is: the initial temperature is 80 °C, it is heated to 145 °C at a rate of 10 °C / min and kept warm for 2 hours, then heated to 170 °C at a rate of 5 °C / min and kept warm for 1 hour, and cooled to 20 °C at a rate of 4 °C / min.

[0044] By adopting the above technical solution, in this application, the prepared thermal insulation material is formed by lamination, and then the prepared thermal insulation material is filled between the inner pipe and the outer pipe to obtain a thermal insulation pipe with compressive and tensile properties.

[0045] In summary, this application includes at least one of the following beneficial technical effects:

[0046] This application discloses a thermal insulation pipe with strong compressive and tensile abilities. The thermal insulation pipe prepared in this application effectively improves the compressive and tensile properties of the thermal insulation pipe while maintaining good thermal insulation performance. Specific Embodiments

[0047] The following further illustrates the technical solution of this application through specific embodiments. The specific embodiments do not represent a limitation on the protection scope of this application; some non-essential modifications and adjustments made by others based on the concept of this application still fall within the protection scope of this application.

[0048] All raw materials involved in this application are commercially available products. Among them,

[0049] Raw materials involved in the preparation of carbon nanotube / polyethylene composite materials:

[0050] Carbon nanotubes, diameter: 40 - 60 nm, length: 5 - 15 μm, molecular weight: 16.04246.

[0051] Maleic anhydride grafted polyethylene, grafting rate 1.5%, addition amount 3% - 5%.

[0052] Carbon black, type JE - 6900, radius 27 nm.

[0053] Polyethylene, high-density polyethylene is selected, density 0.955 g / cm 3 , melt index 5 g / 10 min, Shanghai Secco Petrochemical Co., Ltd.

[0054] Raw materials involved in the preparation of phenolic resin / carbon nanoparticle composite materials:

[0055] Phenolic resin, thermosetting phenolic resin, solid content 70%, Xi'an Aerospace Composite Materials Research Institute.

[0056] Polyurethane, thermoplastic polyurethane, MW = 15 kg·mol -1 , dispersity index PDI = 1, Jiangyin Ideal Rubber & Plastic Technology Co., Ltd.

[0057] Carbon nanoparticles, average particle size of 40 nm, specific surface area of 500 m 2 / g, Beijing Decode Technology Co., Ltd.

[0058] Raw materials involved in the preparation of the insulating pipe:

[0059] Polyethylene, high-density polyethylene is selected, with a density greater than or equal to 0.94 g / cm 3 , and the melt index MI is 0.2 - 0.6 g / 10 min;

[0060] Glass fiber, with a length of 0.1 - 1 mm and a diameter less than 0.01 mm.

[0061] The present application will be further described in detail below in conjunction with examples and comparative examples.

[0062] Source of raw materials:

[0063] Preparation of recycled materials (waste plastic particles):

[0064] The waste plastics are crushed into plastic particles with a mesh size of 60 - 100, soaked in an alkali solution, and then ultrasonically cleaned with a mixture of ethanol and acetone and deionized water in sequence to remove impurities, and then washed with acetone and deionized water, and dried for standby to obtain waste plastic particles.

[0065] Among them, the waste plastics are a mixture of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene in a mass ratio of 1:1:1:1.

[0066] Preparation Example 1:

[0067] Preparation of carbon nanotube / polyethylene composite:

[0068] (1) Mix concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:3 to obtain aqua regia;

[0069] (2) Add 2 g of carbon nanotubes to 100 ml of aqua regia, mix well, and then mix at 140 °C for 40 minutes, filter, wash with deionized water, and dry to obtain modified carbon nanotubes;

[0070] (3) Add 5 g of maleic anhydride-grafted polyethylene to 100 ml of decalin solution, mix at 145 °C for 30 minutes, then add the modified carbon nanotubes, and react at 90 °C for 40 minutes. Filter and dry to obtain functionalized carbon nanotubes;

[0071] (4) Put 2 g of functionalized carbon nanotubes, 2 g of carbon black, and 35 g of polyethylene into a mixer, and knead at 170 °C and 100 rpm for 25 minutes. Cool to room temperature to obtain carbon nanotube / polyethylene composite.

[0072] Preparation Example 2:

[0073] Preparation of carbon nanotube / polyethylene composite:

[0074] (1) Mix concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:3 to obtain aqua regia solution;

[0075] (2) Add 1 g of carbon nanotubes to 100 ml of aqua regia solution, mix well, then mix at 140 °C for 40 minutes, filter, wash with deionized water, and dry to obtain modified carbon nanotubes;

[0076] (3) Add 3 g of maleic anhydride-grafted polyethylene to 100 ml of decalin solution, mix at 145 °C for 30 minutes, then add the modified carbon nanotubes, and react at 90 °C for 40 minutes. Filter and dry to obtain functionalized carbon nanotubes;

[0077] (4) Put 1 g of functionalized carbon nanotubes, 1 g of carbon black, and 30 g of polyethylene into a mixer, and knead at 170 °C and 100 rpm for 25 minutes. Cool to room temperature to obtain carbon nanotube / polyethylene composite.

[0078] Preparation Example 3:

[0079] Preparation of carbon nanotube / polyethylene composite:

[0080] (1) Mix concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:3 to obtain aqua regia solution;

[0081] (2) Add 3 g of carbon nanotubes to 100 ml of aqua regia solution, mix well, then mix at 140 °C for 40 minutes, filter, wash with deionized water, and dry to obtain modified carbon nanotubes;

[0082] (3) Add 7 g of maleic anhydride-grafted polyethylene to 100 ml of decalin solution, mix at 145 °C for 30 minutes, then add the modified carbon nanotubes, and react at 90 °C for 40 minutes. Filter and dry to obtain functionalized carbon nanotubes;

[0083] (4) Put the functionalized carbon nanotubes, 3 g of carbon black, and 40 g of polyethylene into a kneader, knead at 170 °C and a rotation speed of 100 rpm for 25 minutes, and cool to room temperature to obtain a carbon nanotube / polyethylene composite material.

[0084] Preparation Example 4:

[0085] Preparation of phenolic resin / carbon nanoparticle composite material:

[0086] (1) Dissolve 100 g of phenolic resin in 55 g of absolute ethanol, mix at 70 °C for 20 minutes, and add 1.5 g of polyurethane and mix for 30 minutes to obtain a modified phenolic resin;

[0087] (2) After mixing the modified phenolic resin, 75 g of carbon nanoparticles, 8 g of gum arabic, and 2 g of coupling agent KH560 evenly, mix at 80 °C for 4 hours, and cool to room temperature to obtain a phenolic resin / carbon nanoparticle composite material.

[0088] Preparation Example 5:

[0089] Preparation of phenolic resin / carbon nanoparticle composite material:

[0090] (1) Dissolve 50 g of phenolic resin in 50 g of absolute ethanol, mix at 70 °C for 20 minutes, and add 1 g of polyurethane and mix for 30 minutes to obtain a modified phenolic resin;

[0091] (2) After mixing the modified phenolic resin, 60 g of carbon nanoparticles, 5 g of gum arabic, and 1 g of coupling agent KH560 evenly, mix at 80 °C for 4 hours, and cool to room temperature to obtain a phenolic resin / carbon nanoparticle composite material.

[0092] Preparation Example 6:

[0093] Preparation of phenolic resin / carbon nanoparticle composite material:

[0094] (1) Dissolve 150 g of phenolic resin in 60 g of absolute ethanol, mix at 70 °C for 20 minutes, and add 2 g of polyurethane and mix for 30 minutes to obtain a modified phenolic resin;

[0095] (2) After mixing the modified phenolic resin, 90 g of carbon nanoparticles, 10 g of gum arabic, and 3 g of coupling agent KH560 evenly, mix at 80 °C for 4 hours, and cool to room temperature to obtain a phenolic resin / carbon nanoparticle composite material.

[0096] Example 1:

[0097] A preparation method of a heat-insulating pipe with strong compressive and tensile strength. The preparation method of the heat-insulating pipe is as follows:

[0098] Step 1: Preparation of thermal insulation material;

[0099] (1) Modify the glass fiber,

[0100] Mix 1 g of coupling agent KH560 and 4 g of ethanol for 30 minutes, then add 7 g of glass fiber and mix. Place it at 80 °C for 8 hours, filter to obtain the modified glass fiber.

[0101] (2) Mix 7 g of the modified glass fiber, 3 g of coupling agent KH560, 15 g of phenolic resin / carbon nanoparticle composite, and 200 g of deionized water, then add 20 g of carbon nanotube / polyethylene composite and mix; then add 65 g of polyethylene and 25 g of recycled material and mix to obtain the thermal insulation material;

[0102] The carbon nanotube / polyethylene composite is prepared according to Preparation Example 1;

[0103] The phenolic resin / carbon nanoparticle composite is prepared according to Preparation Example 4;

[0104] Step 2: Preparation of thermal insulation pipe;

[0105] (1) Press the thermal insulation material by laminating process:

[0106] Let the thermal insulation material stand at room temperature for 1 hour, then apply a pressure of 5 MPa to the upper surface, set the initial temperature at 80 °C, heat it at a rate of 10 °C / min to 145 °C and keep it warm for 2 hours, then heat it at a rate of 5 °C / min to 170 °C and keep it warm for 1 hour, and cool it at a rate of 4 °C / min to 20 °C to obtain the compression-molded thermal insulation material;

[0107] (2) Fill the pressed thermal insulation material between the inner pipe and the outer pipe to obtain the thermal insulation pipe.

[0108] Example 2:

[0109] A preparation method of a thermal insulation pipe with strong compressive and tensile strength. The preparation method of the thermal insulation pipe is as follows:

[0110] Step 1: Preparation of thermal insulation material;

[0111] (1) Modify the glass fiber,

[0112] Mix 1 g of coupling agent KH560 and 3 g of ethanol for 30 minutes, then add 7 g of glass fiber and mix. Place it at 80 °C for 8 hours, filter to obtain the modified glass fiber.

[0113] (2) 5 g of modified glass fiber, 2 g of coupling agent KH560, 10 g of phenolic resin / carbon nanoparticle composite material, and 200 g of deionized water were mixed, and 15 g of carbon nanotube / polyethylene composite material was added and mixed; 60 g of polyethylene and 20 g of recycled material were added and mixed to obtain a thermal insulation material;

[0114] The carbon nanotube / polyethylene composite material was prepared according to Preparation Example 2;

[0115] The phenolic resin / carbon nanoparticle composite material was prepared according to Preparation Example 5;

[0116] Step 2: Preparation of insulation pipe;

[0117] (1) The insulation material is pressed through a lamination process:

[0118] After the thermal insulation material was allowed to stand at room temperature for 1 hour, a pressure of 5 MPa was applied to the upper surface, and the initial temperature was set to 80°C. The temperature was increased to 145°C at a rate of 10°C / min and maintained for 2 hours. The temperature was then increased to 170°C at a rate of 5°C / min and maintained for 1 hour. The temperature was then decreased to 20°C at a rate of 4°C / min to obtain a press-molded thermal insulation material.

[0119] (2) Fill the compressed insulation material between the inner tube and the outer tube to obtain an insulation tube.

[0120] Example 3:

[0121] A method for preparing a thermal insulation pipe with strong compressive and tensile strength, the method comprising the following steps:

[0122] Step 1: Preparation of insulation materials;

[0123] (1) Modification of glass fiber,

[0124] 1 g of coupling agent KH560 and 5 g of ethanol were mixed for 30 minutes, and then 10 g of glass fiber was added and mixed. The mixture was allowed to stand at 80° C. for 8 hours and filtered to obtain modified glass fiber.

[0125] (2) 10 g of modified glass fiber, 4 g of coupling agent KH560, 20 g of phenolic resin / carbon nanoparticle composite material, and 200 g of deionized water were mixed, and 25 g of carbon nanotube / polyethylene composite material was added and mixed; 70 g of polyethylene and 30 g of recycled material were added and mixed to obtain a thermal insulation material;

[0126] The carbon nanotube / polyethylene composite material was prepared according to Preparation Example 3;

[0127] The phenolic resin / carbon nanoparticle composite material was prepared according to Preparation Example 6;

[0128] Step 2: Preparation of the heat-insulating pipe;

[0129] (1) Press the heat-insulating material through a lamination molding process:

[0130] After standing the heat-insulating material at room temperature for 1 hour, apply a pressure of 5 MPa to the upper surface, set the initial temperature at 80 °C, heat it to 145 °C at a rate of 10 °C / min and hold for 2 hours, then heat it to 170 °C at a rate of 5 °C / min and keep it warm for 1 hour, and cool it to 20 °C at a rate of 4 °C / min to obtain the compression-molded heat-insulating material;

[0131] (2) Fill the compression-molded heat-insulating material between the inner pipe and the outer pipe to obtain the heat-insulating pipe.

[0132] Example 4:

[0133] The difference from Example 1 is that the carbon nanotube / polyethylene composite material is prepared from Preparation Example 2; the phenolic resin / carbon nanoparticle composite material is prepared from Preparation Example 5.

[0134] Example 5:

[0135] The difference from Example 1 is that the carbon nanotube / polyethylene composite material is prepared from Preparation Example 3; the phenolic resin / carbon nanoparticle composite material is prepared from Preparation Example 6.

[0136] Example 6:

[0137] The difference from Example 1 is that the addition amount of the carbon nanotube / polyethylene composite material is 15 g.

[0138] Example 7:

[0139] The difference from Example 1 is that the addition amount of the carbon nanotube / polyethylene composite material is 25 g.

[0140] Example 8:

[0141] The difference from Example 1 is that the addition amount of the phenolic resin / carbon nanoparticle composite material is 10 g.

[0142] Example 9:

[0143] The difference from Example 1 is that the addition amount of the phenolic resin / carbon nanoparticle composite material is 20 g.

[0144] Comparative Example 1:

[0145] The difference from Example 1 is that the phenolic resin / carbon nanoparticle composite material is not added.

[0146] Comparative Example 2:

[0147] The difference from Example 1 is that the glass fiber is not subjected to modification treatment.

[0148] The preparation method of the heat-insulating pipe is as follows:

[0149] Step 1: Preparation of heat-insulating material;

[0150] Mix 7 g of glass fiber, 3 g of coupling agent KH560, 15 g of phenolic resin / carbon nanoparticle composite, and 200 g of deionized water, and then add 20 g of carbon nanotube / polyethylene composite for mixing; then add 65 g of polyethylene and 25 g of recycled material for mixing to obtain the heat-insulating material;

[0151] The carbon nanotube / polyethylene composite is prepared according to Preparation Example 1;

[0152] The phenolic resin / carbon nanoparticle composite is prepared according to Preparation Example 4;

[0153] Step 2: Preparation of heat-insulating pipe;

[0154] (1) Press the heat-insulating material by a lamination molding process:

[0155] After the heat-insulating material is left standing at room temperature for 1 hour, apply a pressure of 5 MPa to the upper surface, set the initial temperature at 80 °C, heat it to 145 °C at a rate of 10 °C / min and hold for 2 hours, then heat it to 170 °C at a rate of 5 °C / min and keep it warm for 1 hour, and cool it to 20 °C at a rate of 4 °C / min to obtain the heat-insulating material formed by pressing;

[0156] (2) Fill the pressed heat-insulating material between the inner pipe and the outer pipe to obtain the heat-insulating pipe.

[0157] Comparative Example 3:

[0158] The difference from Example 1 is that the addition amount of the phenolic resin / carbon nanoparticle composite is 9 g.

[0159] Comparative Example 4:

[0160] The difference from Example 1 is that the addition amount of the phenolic resin / carbon nanoparticle composite is 21 g.

[0161] Comparative Example 1:

[0162] The difference from Example 1 is that the carbon nanotube / polyethylene composite is not added.

[0163] Comparative Example 2:

[0164] The difference from Example 1 is that the addition amount of the carbon nanotube / polyethylene composite material is 14 g.

[0165] Comparative Example 3:

[0166] The difference from Example 1 is that the addition amount of the carbon nanotube / polyethylene composite material is 26 g.

[0167] Performance detection:

[0168] 1. Detection of tensile strength, impact strength, flexural strength, and longitudinal shrinkage rate:

[0169] The performance of the insulation pipes prepared in the above examples, comparative examples, and comparative examples was detected, and the detection standards are as follows.

[0170] (1) Longitudinal shrinkage rate: Detected according to GB / T 6671-2001 "Determination of Longitudinal Shrinkage Rate of Thermoplastic Plastic Pipes";

[0171] (2) Determination of tensile strength: Detected according to GB / T 1447-2005 "Test Method for Tensile Properties of Fiber Reinforced Plastics";

[0172] (3) Determination of impact strength: Detected according to GB / T 1843-2008 "Determination of Plastic Izod Impact Strength";

[0173] (4) Determination of flexural strength: Detected according to GB / T 9341-2008 "Test Method for Plastic Flexure Determination".

[0174] The detection results are shown in the table:

[0175] Table 1 Performance Detection Results of Insulation Pipes

[0176]

[0177] It can be seen from Table 1 that the insulation pipes prepared by the scheme of the present application (Examples 1-9) have been significantly improved in terms of longitudinal shrinkage rate, tensile strength, impact strength, flexural strength, etc., indicating that the insulation pipes prepared by the present application have better comprehensive properties such as strength, impact resistance, and toughness.

[0178] Combining Example 1 and Comparative Example 2, it can be seen that the longitudinal shrinkage rate, tensile strength, impact strength, and flexural strength of Example 1 are better than those of Comparative Example 2, indicating that when preparing the insulation pipe, the modification treatment of the glass fiber effectively improves the compatibility of the glass fiber with other raw materials, enables the glass fiber to be better mixed with other raw materials, and further improves the strength, impact resistance, and toughness of the insulation pipe.

[0179] Combined with Example 1 and Comparative Example 1, it can be seen that the longitudinal shrinkage rate, tensile strength, impact strength, and flexural strength of Example 1 are superior to those of Comparative Example 1, indicating that the addition of the carbon nanotube / polyethylene composite effectively improves the strength, impact resistance, and toughness of the insulation pipe.

[0180] Combined with Example 1, Example 6, Example 7, Comparative Example 2, and Comparative Example 3, it can be seen that the addition amount of the carbon nanotube / polyethylene composite has a certain influence on the longitudinal shrinkage rate, tensile strength, impact strength, and flexural strength. And when the addition amount of the carbon nanotube / polyethylene composite is 15 - 25 g, the strength, impact resistance, and toughness of the insulation pipe are the best.

[0181] 2. Pressure Resistance Test

[0182] The pressure resistance performance of the insulation pipes prepared in the above examples, comparative examples, and comparative examples was detected. The detection standard is "GB / T6111 - 2003 Test Method for Internal Pressure Resistance of Thermoplastic Pipe for Fluid Transportation". The test results are shown in the following table:

[0183] Table 2 Detection Results of Pressure Resistance Test

[0184]

[0185] It can be seen from Table 2 that the pressure resistance performance of the insulation pipes prepared by the scheme of the present application (Examples 1 - 9) has been significantly improved, indicating that the pressure resistance performance of the insulation pipes prepared by the present application is better.

[0186] Combined with Example 1 and Comparative Example 2, it can be seen that the pressure resistance performance of Example 1 is superior to that of Comparative Example 2, indicating that when preparing the insulation pipe, the modification treatment of the glass fiber effectively improves the compatibility between the glass fiber and other raw materials, enables the glass fiber to be better mixed with other raw materials, and further improves the pressure resistance performance of the insulation pipe.

[0187] Combined with Example 1 and Comparative Example 1, it can be seen that the pressure resistance performance of Example 1 is superior to that of Comparative Example 1, indicating that the addition of the carbon nanotube / polyethylene composite effectively improves the pressure resistance performance of the insulation pipe.

[0188] Combined with Example 1, Example 6, Example 7, Comparative Example 2, and Comparative Example 3, it can be seen that the addition amount of the carbon nanotube / polyethylene composite has a certain influence on the pressure resistance performance. And when the addition amount of the carbon nanotube / polyethylene composite is 15 - 25 g, the pressure resistance performance effect of the insulation pipe is the best.

[0189] 3. Detection of Thermal Conductivity Coefficient:

[0190] The heat preservation pipes prepared in the above-mentioned examples, comparative examples, and comparative ratios were cut into short pipes with a length of 50 cm, and 100 pipes were selected from each example for the detection of the heat conduction coefficient. The average value was calculated, and the results are shown in the following table:

[0191] Table 3 Detection Results of Heat Conduction Coefficient

[0192]

[0193] As can be seen from Table 3, the heat preservation pipes prepared by the solution of the present application (Examples 1-9) have been significantly improved in terms of heat preservation performance, indicating that the heat preservation pipes prepared by the present application have better heat preservation performance.

[0194] Combined with Example 1 and Comparative Example 1, it can be seen that the heat conduction coefficient of Example 1 is better than that of Comparative Example 1, indicating that the addition of the phenolic resin / carbon nanoparticle composite effectively improves the heat preservation performance of the heat preservation pipe.

[0195] Combined with Example 1 and Comparative Example 2, it can be seen that the heat conduction coefficient of Example 1 is better than that of Comparative Example 2, indicating that when preparing the heat preservation pipe, the modification treatment of the glass fiber effectively improves the compatibility of the glass fiber with other raw materials, enables the glass fiber to be better mixed with other raw materials, and further improves the heat preservation performance of the heat preservation pipe.

[0196] Combined with Example 1, Example 8, Example 9, Comparative Example 3, and Comparative Example 4, it can be seen that the addition amount of the phenolic resin / carbon nanoparticle composite has an impact on the heat preservation performance of the heat preservation pipe, and when the addition amount of the phenolic resin / carbon nanoparticle composite is 10-20 g, the heat preservation performance effect of the heat preservation pipe is the best.

[0197] The heat preservation pipe prepared by the present application is particularly suitable for fluid transmission in high-temperature environments in industries such as urban heating / cooling, industrial steam high-pressure transmission, etc., ensuring effective heat transfer and reducing heat energy loss at the same time.

Claims

1. A heat-insulating pipe with strong compressive and tensile resistance, characterized in that, It includes a coaxial inner tube and outer tube, and heat-insulating material is filled between the inner tube and the outer tube; The heat-insulating material includes raw materials in the following parts by mass: 60-70 parts of polyethylene, 20-30 parts of recycled material, 5-10 parts of glass fiber, 2-4 parts of coupling agent, and 15-25 parts of carbon nanotube / polyethylene composite material; Among them, the carbon nanotube / polyethylene composite material includes raw materials in the following parts by mass: 30-40 parts of polyethylene, 1-3 parts of carbon nanotube, 1-3 parts of carbon black, and 3-7 parts of maleic anhydride grafted polyethylene; The heat-insulating material further includes 10-20 parts by mass of phenolic resin / carbon nanoparticle composite material; The phenolic resin / carbon nanoparticle composite material includes raw materials in the following parts by mass: 60-90 parts of carbon nanoparticles, 50-150 parts of phenolic resin, 1-2 parts of polyurethane, 50-60 parts of absolute ethanol, 5-10 parts of gum arabic, and 1-3 parts of coupling agent; The preparation method of the phenolic resin / carbon nanoparticle composite material is as follows: Weigh each raw material according to the formula; Mix phenolic resin and absolute ethanol, and add polyurethane for mixing to obtain modified phenolic resin; Mix the modified phenolic resin, carbon nanoparticles, gum arabic, and coupling agent to obtain the phenolic resin / carbon nanoparticle composite material; The modification treatment of glass fiber is as follows: Mix the coupling agent and ethanol, add glass fiber for mixing, place it at 80-100 °C for 8-10 hours, and filter to obtain the modified glass fiber.

2. The heat-insulating pipe with strong compressive and tensile resistance according to claim 1, wherein The preparation steps of the carbon nanotube / polyethylene composite material are as follows: Weigh each raw material according to the formula; Add carbon nanotubes to aqua regia solution for mixing, and filter to obtain modified carbon nanotubes; Mix the modified carbon nanotubes and maleic anhydride grafted polyethylene, filter, add polyethylene and carbon black for mixing to obtain the carbon nanotube / polyethylene composite material.

3. The heat-insulating pipe with strong compressive and tensile resistance according to claim 1, wherein: The mass ratio of the coupling agent to ethanol is 1:(3-5); the mass ratio of the glass fiber to the coupling agent is (5-10):(1-2).

4. A heat-insulating pipe with strong compressive and tensile resistance according to claim 1, characterized in that: The recycled material is waste plastic particles, and the waste plastic is at least one of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene.

5. A method for preparing the heat-insulating pipe with strong compressive and tensile resistance according to any one of claims 1-4, characterized in that, The preparation method is as follows: (1) Preparation of heat-insulating material: Weigh each raw material according to the formula; Mix glass fiber, coupling agent, and phenolic resin / carbon nanoparticle composite material, add carbon nanotube / polyethylene composite material for mixing; then add polyethylene and recycled material for mixing to obtain the heat-insulating material; (2) Preparation of heat-insulating tube; Press the heat-insulating material by a lamination molding process, and fill the pressed heat-insulating material between the inner tube and the outer tube to obtain the heat-insulating tube.

6. The preparation method of the heat-insulating tube with strong compressive and tensile strength according to claim 5, characterized in that: In the lamination molding process, the reaction pressure is 5 MPa; The reaction temperature is: the initial temperature is 80 °C, it is heated to 145 °C at a rate of 10 °C / min and kept warm for 2 hours, then heated to 170 °C at a rate of 5 °C / min and kept warm for 1 hour, and cooled to 20 °C at a rate of 4 °C / min.

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