Composite LLDPE polyethylene burn-proof PTE tube

Abstract

The invention discloses a composite LLDPE polyethylene anti-burn PTE tube, and relates to the field of high polymer material plastic products. The composite LLDPE anti-burn PTE tube is of a three-layer co-extrusion integrated thin-wall high-strength structure with linear low density polyethylene as a unified base material, and sequentially comprises an inner reinforcing layer with a smooth inner wall, a corrugated middle heat insulation layer and a high-reflection outer protection layer from inside to outside, the three-layer structure realizes interlayer gapless tight combination through raw material particle size matching and melt flow rate regulation and control. According to the composite LLDPE polyethylene anti-burn PTE pipe, the inner layer, the middle layer and the outer layer have functional positioning and are accurate in raw material ratio design, the inner strengthening layer is modified by nano carbon black, the corrugated middle heat insulation layer is reinforced by aluminum oxide ceramic filler, and the high-reflection outer protection layer is designed by light scattering of titanium dioxide white master batch, so that the pipe integrates wear resistance, heat insulation, burn prevention and weather resistance; the limitation that a traditional polyethylene pipe is single in function is broken through, and the fluid conveying requirement under the severe environment is met.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and plastic products, and in particular to a composite LLDPE polyethylene anti-scalding PTE pipe. Background Technology

[0002] With the acceleration of urbanization and the upgrading of industrial infrastructure, polyethylene (PE) pipes have been widely used in municipal water supply and drainage, gas transmission, chemical fluid transportation and other fields due to their advantages such as corrosion resistance and good flexibility.

[0003] However, traditional single-layer polyethylene pipes have significant performance bottlenecks: HDPE pipes are prone to stress cracking under long-term high pressure, while MDPE pipes improve creep resistance but sacrifice flexibility, and the penetration of oil and gas media can easily cause pipe wall swelling, reducing transportation efficiency; although existing polyethylene multilayer composite pipes have better performance than single-layer pipes, they generally have the problem of simple three-layer structure combination and large differences in polarity of materials in each layer, resulting in poor interlayer interface compatibility. Some pipes are prone to melt fracture during co-extrusion due to the large difference in melt flow rate between each layer. At the same time, traditional multilayer pipes cannot take into account multiple properties such as weather resistance, heat insulation, high strength, and anti-scalding, and cannot meet the usage requirements of extreme working conditions such as strong light, humid heat, and alternating high and low temperatures. Summary of the Invention

[0004] The purpose of this invention is to provide a composite LLDPE polyethylene anti-scalding PTE pipe to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a composite LLDPE polyethylene anti-scalding PTE pipe, wherein the PTE pipe is a three-layer co-extruded integrated thin-walled high-strength structure with linear low-density polyethylene as the unified substrate, consisting of an inner reinforcing layer with a smooth inner wall, a corrugated middle heat insulation layer, and a high-reflectivity outer protective layer from the inside out. The three-layer structure achieves a tight bond between the layers without gaps through matching the raw material particle size and controlling the melt flow rate. The inner reinforcing layer is a blended modified layer of LLDPE particles and nano carbon black, with a mass ratio of LLDPE particles to carbon black of 95-97:3-5 and a carbon black particle size of 20-40 nm. The corrugated intermediate heat insulation layer is a blended reinforcement layer of LLDPE particles and ceramic heat insulation filler, with a mass ratio of LLDPE particles to ceramic heat insulation filler of 70-85:15-30, and the ceramic heat insulation filler is alumina with a particle size of 0.05-0.5μm. The high-reflectivity outer protective layer is a blend of LLDPE particles and high-reflectivity white masterbatch to prevent burns. The mass ratio of LLDPE particles to white masterbatch is 90-95:5-10. The white masterbatch has a particle size of 0.2-0.5μm and its main component is titanium dioxide. The titanium dioxide and the LLDPE substrate form a refractive index difference and constitute an efficient light scattering network inside the substrate, so that the high-reflectivity outer protective layer has a reflectivity of ≥85% for sunlight.

[0006] Preferably, the LLDPE particles used in the inner reinforcing layer, the corrugated intermediate heat insulation layer, and the high-reflectivity outer protective layer all have a particle size of 20-50μm, and the difference in melt flow rate of each layer of raw materials is controlled within 5%, so as to achieve precise matching of melt compatibility during three-layer co-extrusion.

[0007] Preferably, the friction coefficient of the smooth inner wall of the inner reinforcing layer is ≤0.15, which combines wear resistance, corrosion resistance, flame retardancy and low friction lubrication properties, so as to realize the rapid and low resistance flow of fluid in the pipeline.

[0008] Preferably, the titanium dioxide in the white masterbatch is rutile titanium dioxide, which has a light absorption rate of ≤5% in the visible and near-infrared bands. After multiple refractions and scatterings, it achieves efficient reverse reflection of sunlight and blocks ultraviolet rays from aging and corroding the pipe body.

[0009] Preferably, the PTE tube has a crystallinity of 60%, a room temperature static tensile strength of 21 MPa, an elongation at break of ≥350%, and an impact strength of 12 KJ / m², with its mechanical properties and environmental adaptability to high and low temperatures and crack resistance being synergistically optimized.

[0010] Preferably, the specifications of the PTE pipe are: pipe diameter Φ16-Φ40mm, wall thickness 0.5-2.5mm, and rated working pressure 0.6MPa.

[0011] Preferably, the corrugated height of the corrugated intermediate heat insulation layer is 0.3-1.0 mm, and the corrugation spacing is 1.0-2.0 mm. The corrugated structure improves the heat insulation efficiency by increasing the heat conduction path, and at the same time, it works synergistically with the alumina filler to enhance the ring stiffness and compressive strength of the tube.

[0012] Preferably, the alumina filler in the corrugated intermediate heat insulation layer is nano-sized alumina powder, which is uniformly dispersed in the LLDPE substrate, achieving efficient barrier against heat and cold conduction without reducing the flexibility and impact resistance of the tube.

[0013] Preferably, the high-reflectivity outer protective layer has a dense structure, a smooth and pore-free surface, and titanium dioxide particles are uniformly distributed within the protective layer. The light scattering network has no local breaks, ensuring that the solar reflectivity of each part of the tube is ≥85%.

[0014] Preferably, the PTE tube has a density of 0.91–0.93 g / cm³, a low-temperature embrittlement temperature < -90°C, and exhibits no cracking or leakage after being pressurized for 100 hours under a ring stress of 1.2 MPa at room temperature, and withstands pressure changes at 55°C. The environmental stress cracking strength under slow strain rate tension is ≥12MPa, and the ratio of wall thickness to pipe diameter is 0.03-0.06.

[0015] The technical effects and advantages of this invention are as follows: By using linear low-density polyethylene as a unified base material, the polarity difference between different base materials is reduced from the source. Combined with the matching of raw material particle size and the control of melt flow rate, a tight bond without gaps between the three-layer structure is achieved, solving the technical pain point of poor interfacial compatibility between the layers of traditional three-layer composite pipes. The inner, middle and outer layers each have their own functional positioning and the raw material ratio is precisely designed. The nano-carbon black modification of the inner reinforcing layer, the alumina ceramic filler reinforcement of the corrugated middle heat insulation layer, and the light scattering design of the titanium dioxide white masterbatch of the high-reflectivity outer protective layer make the pipe integrate wear resistance, heat insulation, anti-scalding and weather resistance, breaking through the limitation of the single function of traditional polyethylene pipes and meeting the fluid transportation needs in harsh environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the microstructure of the LLDPE tube of the present invention.

[0017] In the diagram: 1. Inner reinforcing layer; 2. Corrugated intermediate heat insulation layer; 3. High-reflectivity outer protective layer. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides, for example Figure 1 The present invention is a composite LLDPE polyethylene anti-burn PTE pipe. The PTE pipe is a three-layer co-extruded integrated thin-walled high-strength structure with linear low-density polyethylene as the unified base material. From the inside to the outside, it consists of an inner reinforcing layer 1 with a smooth inner wall, a corrugated middle heat insulation layer 2, and a high-reflection outer protective layer 3. The three-layer structure achieves a tight bond between the layers without gaps by matching the raw material particle size and controlling the melt flow rate. The inner reinforcing layer 1 is a blended modification layer of LLDPE particles and nano carbon black, with a mass ratio of LLDPE particles to carbon black of 95-97:3-5 and a carbon black particle size of 20-40nm. The corrugated intermediate heat insulation layer 2 is a blended reinforcement layer of LLDPE particles and ceramic heat insulation filler. The mass ratio of LLDPE particles to ceramic heat insulation filler is 70-85:15-30. The ceramic heat insulation filler is alumina with a particle size of 0.05-0.5μm. The high-reflectivity outer protective layer 3 is a blend of LLDPE particles and high-reflectivity white masterbatch to prevent burns. The mass ratio of LLDPE particles to white masterbatch is 90-95:5-10. The white masterbatch has a particle size of 0.2-0.5μm and its main component is titanium dioxide. The titanium dioxide and the LLDPE substrate form a refractive index difference and constitute an efficient light scattering network inside the substrate, so that the high-reflectivity outer protective layer 3 has a reflectivity of ≥85% for sunlight.

[0020] Using linear low-density polyethylene as a unified base material, the polarity difference between different base materials is reduced from the source. Combined with raw material particle size matching and melt flow rate control, a tight bond without gaps between the three layers is achieved, solving the technical pain point of poor interfacial compatibility between traditional three-layer composite pipes. The inner, middle and outer layers each have their own functional positioning and the raw material ratio is precisely designed. The inner reinforcing layer 1 is modified with nano carbon black, the corrugated middle heat insulation layer 2 is reinforced with alumina ceramic filler, and the high-reflectivity outer protective layer 3 is designed with titanium dioxide white masterbatch light scattering, so that the pipe integrates wear resistance, heat insulation, anti-scalding and weather resistance, breaking through the limitation of the single function of traditional polyethylene pipes and meeting the fluid transportation needs in harsh environments.

[0021] Furthermore, the LLDPE particles used in the inner reinforcing layer 1, the corrugated intermediate heat insulation layer 2, and the high-reflectivity outer protective layer 3 all have a particle size of 20-50μm, and the difference in melt flow rate of each layer of raw materials is controlled within 5%, so as to achieve precise matching of melt compatibility during three-layer co-extrusion.

[0022] By unifying the particle size of LLDPE particles in each layer and precisely controlling the difference in melt flow rate, the melt fracture problem caused by excessive difference in melt flow rate in the traditional three-layer co-extrusion process is avoided. This improves the process stability of three-layer co-extrusion molding, ensures the integrity and density of the pipe structure after molding, further strengthens the interlayer bonding effect, and reduces pipe molding defects.

[0023] Furthermore, the inner wall of the inner reinforcement layer 1 has a friction coefficient of ≤0.15, and combines wear resistance, corrosion resistance, flame retardancy and low friction lubrication properties to achieve rapid and low resistance flow of fluid in the pipeline.

[0024] The low friction coefficient design of the smooth inner wall effectively reduces the flow resistance of fluid in the pipeline, improves fluid transportation efficiency, and reduces energy consumption; the blending modification of nano carbon black gives the inner reinforcing layer 1 multiple properties such as wear resistance, corrosion resistance, and flame retardancy, which can adapt to the complex transportation environment of high temperature and high pressure, prevent the inner wall of the pipe from being damaged by fluid scouring and media corrosion, and at the same time improve the safe use performance of the pipe and avoid the risk of combustion under high temperature conditions.

[0025] Furthermore, the titanium dioxide in the white masterbatch is rutile titanium dioxide, which has a light absorption rate of ≤5% in the visible and near-infrared bands. After multiple refractions and scatterings, it achieves efficient reverse reflection of sunlight and blocks ultraviolet rays from aging and corroding the pipe body.

[0026] Rutile titanium dioxide possesses excellent optical properties and weather resistance. Its low absorption rate in the visible and near-infrared bands ensures that a large amount of solar energy is not converted into heat. Through multiple refractions and scattering, it achieves a solar reflectivity of ≥85%, effectively reducing the surface temperature of the pipe and achieving a burn-proof effect. At the same time, rutile titanium dioxide can effectively block ultraviolet rays, preventing ultraviolet rays from aging and corroding the LLDPE substrate, and significantly extending the outdoor service life of the pipe.

[0027] Furthermore, the PTE tube has a crystallinity of 60%, a room temperature static tensile strength of 21 MPa, an elongation at break of ≥350%, and an impact strength of 12 KJ / m². Its mechanical properties are synergistically optimized with environmental adaptability such as high and low temperatures and crack resistance.

[0028] The 60% crystallinity gives the pipe both rigidity and flexibility. Combined with precisely controlled room temperature static tensile strength, elongation at break, and impact strength, the pipe has excellent mechanical properties and can withstand pressure shocks during fluid transportation and external mechanical collisions. The synergistic optimization of mechanical properties and environmental adaptability such as high and low temperature and crack resistance allows the pipe to maintain stable performance under different temperatures and stress environments, thus improving the pipe's environmental adaptability.

[0029] Furthermore, the specifications for PTE pipes are as follows: pipe diameter Φ16-Φ40mm, wall thickness 0.5-2.5mm, and rated working pressure 0.6MPa.

[0030] While ensuring the rated working pressure of 0.6MPa, the material consumption of the pipe is effectively reduced, the weight of the pipe is reduced, and the transportation and construction installation are facilitated. The pipe diameter range of Φ16-Φ40mm is suitable for the pipeline laying needs of various scenarios such as agricultural irrigation, small industrial fluid transportation, and municipal small water supply and drainage, thus improving the applicability of the pipe.

[0031] Furthermore, the corrugated intermediate heat insulation layer 2 has a corrugation height of 0.3-1.0 mm and a corrugation spacing of 1.0-2.0 mm. The corrugated structure improves the heat insulation efficiency by increasing the heat conduction path, and at the same time, it works synergistically with the alumina filler to enhance the ring stiffness and compressive strength of the tube. Moreover, the corrugated structure can increase its contact area with the inner and outer layers, which is beneficial to improving the interlayer bonding strength.

[0032] The corrugated structure with specific parameters increases the heat conduction path of the pipe body. Combined with the thermal insulation properties of alumina filler, it achieves a double improvement in thermal insulation efficiency. It can effectively block the conduction of external high or low temperatures into the pipe body, ensure the stability of the fluid temperature inside the pipe, and reduce energy consumption during transportation. The three-dimensional support of the corrugated structure and the reinforcing effect of alumina filler work together to significantly improve the ring stiffness and compressive strength of the pipe body, prevent the pipe from deforming due to external pressure in scenarios such as direct burial and outdoor stacking, and improve the structural stability of the pipe.

[0033] Furthermore, the alumina filler in the corrugated intermediate heat insulation layer 2 is nano-sized alumina powder, which is uniformly dispersed in the LLDPE substrate, achieving efficient barrier against heat and cold conduction without reducing the flexibility and impact resistance of the tube.

[0034] The uniform dispersion of nano-sized alumina powder enables it to form a dense thermal insulation network within the LLDPE substrate, achieving efficient blocking of heat and cold conduction and improving thermal insulation performance. At the same time, the dispersion characteristics of the nano-sized filler do not damage the molecular structure of the LLDPE substrate, ensuring that the pipe retains the flexibility and impact resistance of linear low-density polyethylene itself. This solves the technical problem of decreased flexibility after adding thermal insulation fillers to traditional composite pipes, allowing the pipe to have both excellent thermal insulation and impact resistance.

[0035] Furthermore, the high-reflectivity outer protective layer 3 has a dense structure with a smooth, non-porous surface. Titanium dioxide particles are uniformly distributed within the protective layer, and the light scattering network has no local breaks, ensuring that the solar reflectivity of all parts of the tube is ≥85%.

[0036] The dense, smooth, and non-porous structural design enhances the waterproof and corrosion-resistant performance of the outer protective layer, preventing external moisture and corrosive media from invading the tube body and causing interlayer separation or substrate aging. The uniform distribution of titanium dioxide particles ensures that the light scattering network has no local breaks, guaranteeing that the solar reflectivity of all parts of the tube body can reach ≥85%, achieving all-round protection against burns and UV aging, and avoiding problems such as excessively high temperature and accelerated aging in local areas due to insufficient reflectivity.

[0037] Furthermore, the PTE pipe has a density of 0.91–0.93 g / cm³, a low-temperature embrittlement temperature < -90℃, and exhibits no cracking or leakage after being pressure-held for 100 hours under a ring stress of 1.2 MPa at room temperature. It also withstands pressure at 55℃. The environmental stress cracking strength under slow strain rate tension is ≥12MPa, and the ratio of wall thickness to pipe diameter is 0.03-0.06.

[0038] The low density of 0.91~0.93g / cm³ makes the pipe lightweight, facilitating transportation, construction, and installation, thus reducing construction costs. A low-temperature embrittlement temperature of <-90℃ allows the pipe to be used normally in ultra-low temperature environments without low-temperature cracking, improving its adaptability to low-temperature environments. Excellent hydrostatic strength and resistance to environmental stress cracking ensure that the pipe remains crack-free and leak-free under long-term high-pressure and high-temperature stress conditions, solving the technical bottleneck of traditional polyethylene pipes' susceptibility to stress cracking. A wall thickness to diameter ratio of 0.03-0.06 precisely matches the thin-walled, high-strength structural design, achieving lightweight design while ensuring structural strength and performance.

[0039] This composite LLDPE polyethylene anti-scalding PTE pipe is manufactured using a three-layer co-extrusion process, combining key technologies such as precise raw material mixing, particle size control, and melt rate matching. The specific manufacturing steps are as follows: Step 1: Raw Material Selection Linear low-density polyethylene particles with a particle size of 20-50 μm are selected as the uniform substrate; nano-carbon black with a particle size of 20-40 nm is selected as the modified raw material for the inner reinforcing layer 1; nano-alumina micro powder with a particle size of 0.05-0.5 μm is selected as the ceramic heat insulation filler for the corrugated intermediate heat insulation layer 2; and high-reflectivity white masterbatch with a particle size of 0.2-0.5 μm and rutile titanium dioxide as the main component is selected as the anti-scalding modified raw material for the high-reflectivity outer protective layer 3. The difference in melt flow rate of each layer of raw material is controlled within 5%.

[0040] Step 2: Raw material mixing The raw materials for each layer were prepared according to the following proportions: Inner reinforcing layer 1 was a mixture of LLDPE granules and carbon black at a mass ratio of 95-97:3-5; Corrugated intermediate heat insulation layer 2 was a mixture of LLDPE granules and alumina micro powder at a mass ratio of 70-85:15-30; and high-reflectivity outer protective layer 3 was a mixture of LLDPE granules and white masterbatch at a mass ratio of 90-95:5-10. Each layer of raw materials was then fed into a high-energy ball mill and ball-milled at 2000 r / min for 2-3 hours to embed the nanoparticles into the polyethylene granules, ensuring uniform mixing of the raw materials.

[0041] Step 3: Three-layer co-extrusion molding The mixed inner reinforcing layer 1 raw material is added to the first feed port of the extruder, the corrugated intermediate heat insulation layer 2 raw material is added to the second feed port, and the high-reflectivity outer protective layer 3 raw material is added to the third feed port. The temperature of the IV zone of the extruder is controlled at 160~210℃. The extruder is started so that the three layers of raw materials are fully mixed in the mixing chamber and then conveyed to the three-layer co-extrusion die through the spiral extrusion tube for joint extrusion. The corrugated structure of the corrugated intermediate heat insulation layer 2 is formed simultaneously at the die, realizing the integrated co-extrusion molding of the three-layer structure.

[0042] Step 4: Cooling and Shaping The pipe blank extruded from the three-layer co-extrusion die is cooled to quickly shape the pipe, ensuring the structural dimensional accuracy of the pipe and the tightness of the bonding between each layer, thus forming a composite LLDPE polyethylene anti-scalding PTE pipe blank.

[0043] Step 5: Inspect the cut First, the shaped pipes undergo a visual inspection to ensure a smooth surface free of cracks, bulges, scratches, and other defects. Second, the physical and mechanical properties, hydrostatic strength, and resistance to environmental stress cracking of the pipes are tested according to the PE80 grade water supply pipe standard in GB / T13663 "PE Pipe Systems for Water Supply" to ensure that all indicators meet the technical requirements of the pipes. Finally, the qualified pipes are precisely cut according to actual usage needs to obtain finished composite LLDPE polyethylene anti-scalding PTE pipes.

[0044] Reference Appendix Figure 2 The microstructure of the LLDPE pipe is shown in Figure 1, where: Figure 1a is a cross-section of the LLDPE pipe, Figure 2b is an LLDPE layer, Figure 3c is an enlarged view of the boxed area in Figure 2b, Figure 4d is a carbon black layer, Figure 5e is an enlarged view of the boxed area in Figure 3d, Figure 6f is an energy dispersive spectroscopy (EDS) spectrum of region A, and Figure 7g is an EDS spectrum of region B.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite LLDPE polyethylene anti-scalding PTE pipe, characterized in that, The PTE pipe is a three-layer co-extruded integrated thin-walled high-strength structure with linear low-density polyethylene as the unified base material. From the inside to the outside, it consists of an inner reinforcing layer (1) with a smooth inner wall, a corrugated middle heat insulation layer (2) and a high-reflection outer protective layer (3). The three-layer structure achieves a tight bond between the layers without gaps by matching the raw material particle size and controlling the melt flow rate. The inner reinforcing layer (1) is a blended modified layer of LLDPE particles and nano carbon black; The corrugated intermediate heat insulation layer (2) is a blended reinforcement layer of LLDPE particles and ceramic heat insulation filler; The high-reflectivity outer protective layer (3) is a blend of LLDPE particles and high-reflectivity white masterbatch to prevent burns.

2. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The mass ratio of LLDPE particles to carbon black is 95-97:3-5, the carbon black particle size is 20-40nm, the mass ratio of LLDPE particles to ceramic heat insulation filler is 70-85:15-30, the ceramic heat insulation filler is alumina with a particle size of 0.05-0.5μm, the mass ratio of LLDPE particles to white masterbatch is 90-95:5-10, the white masterbatch particle size is 0.2-0.5μm and the main component is titanium dioxide. Titanium dioxide and LLDPE substrate form a refractive index difference and form an efficient light scattering network inside the substrate, so that the high reflectivity outer protective layer (3) has a reflectivity of ≥85% for sunlight.

3. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The LLDPE particles used in the inner reinforcing layer (1), the corrugated intermediate heat insulation layer (2), and the high-reflectivity outer protective layer (3) all have a particle size of 20-50 μm.

4. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The friction coefficient of the smooth inner wall of the inner reinforcing layer (1) is ≤0.15, and the titanium dioxide in the white masterbatch is rutile titanium dioxide with a light absorption rate of ≤5% in the visible and near-infrared bands.

5. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The PTE tube has a crystallinity of 60%, a room temperature static tensile strength of 21 MPa, an elongation at break of ≥350%, and an impact strength of 12 KJ / m².

6. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The specifications of the PTE pipe are as follows: pipe diameter Φ16-Φ40mm, wall thickness 0.5-2.5mm, and rated working pressure 0.6MPa.

7. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The corrugated intermediate heat insulation layer (2) has a corrugation height of 0.3-1.0 mm and a corrugation spacing of 1.0-2.0 mm.

8. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The alumina filler of the corrugated intermediate heat insulation layer (2) is nano-sized alumina powder, which is uniformly dispersed in the LLDPE substrate.

9. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The high-reflectivity outer protective layer (3) has a dense structure, a smooth surface without pores, and titanium dioxide particles are uniformly distributed within the protective layer.

10. The composite LLDPE polyethylene anti-scalding PTE pipe according to claim 1, characterized in that, The PTE tube has a density of 0.91–0.93 g / cm³, a low-temperature embrittlement temperature < -90℃, and exhibits no cracking or leakage after being pressure-held for 100 hours under a ring stress of 1.2 MPa at room temperature. It also withstands pressure at 55℃. The environmental stress cracking strength under slow strain rate tension is ≥12MPa, and the ratio of wall thickness to pipe diameter is 0.03-0.06.

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