Environment-friendly recyclable CPVC cable protection pipe and preparation method thereof

Abstract

This invention belongs to the field of cable protection pipe technology, and discloses an environmentally friendly recyclable CPVC cable protection pipe and its preparation and recycling methods. It includes an outer protective pipe and an inner buffer pipe, which are detachably connected by a spiral groove and a raised buckle. The material is a blend of chlorinated polyvinyl chloride and polyvinyl chloride, with rare earth composite stabilizers and environmentally friendly flame retardants added to replace traditional toxic additives. The outer layer is coated with an anti-aging coating, and the inner layer has buffer ridges. It is prepared using a layered extrusion process, and after recycling, it can be sorted, crushed, and reprocessed into recycled pipes after blending modification. This protective pipe is environmentally friendly, non-toxic, recyclable, easy to install and maintain, effectively protects cables, and has excellent anti-aging and flame-retardant properties, achieving closed-loop resource utilization and solving the defects of existing pipes such as poor environmental performance, difficulty in recycling, and inadequate protective effect.

Description

Technical Field

[0001] This invention relates to the field of cable protection pipe technology, specifically to an environmentally friendly recyclable CPVC cable protection pipe and its preparation method. Background Technology

[0002] Currently, most CPVC cable protection pipes on the market use traditional toxic metal stabilizers and halogen flame retardants, which easily generate toxic and harmful substances during use, failing to meet environmental protection requirements. Furthermore, they are difficult to recycle and reuse after disposal, resulting in resource waste and environmental pollution. Simultaneously, traditional cable protection pipes are mostly single-layer structures, lacking effective buffering and shock absorption designs. This leads to significant friction between the cable and the inner wall of the pipe, easily damaging the cable insulation layer. Moreover, the outer protective structure has poor anti-aging and anti-corrosion properties, easily aging and breaking down with long-term use, failing to provide long-term stable protection for cables. In addition, traditional pipes are mostly one-piece molded structures, unable to be disassembled, making installation and maintenance inconvenient. Furthermore, recycling requires complete crushing, which easily causes material degradation, affecting the performance of recycled materials. To address the shortcomings of existing technologies, there is an urgent need for an environmentally friendly, recyclable, highly protective, and easy-to-install and maintain CPVC cable protection pipe to overcome the many defects of existing pipe materials.

[0003] Therefore, an environmentally friendly recyclable CPVC cable protection pipe and its preparation method are proposed. Summary of the Invention

[0004] The present invention aims to solve the problems mentioned in the background art by providing an environmentally friendly recyclable CPVC cable protection pipe and its preparation method.

[0005] Terminology Explanation Blended substrate: In this invention, it specifically refers to the mixture of chlorinated polyvinyl chloride and polyvinyl chloride in a certain proportion, which is the core substrate of the pipe material. All other additives are added based on this blended substrate according to the relative mass fraction. Mass recovery rate: refers to the ratio of the mass of pure CPVC / PVC recycled particles obtained after sorting, crushing and drying to the total mass of recycled waste pipes; Recycled material purity: refers to the mass percentage of CPVC / PVC blended base material in the recycled granules, with the remainder being trace residues after impurities have been removed; Coating adhesion rating: Tested using the cross-cut method, referring to GB / T9286-1998 standard, Grade 1 means that the cut edge of the coating is completely smooth and there is no peeling. The specific technical solution is as follows: An environmentally friendly, recyclable CPVC cable protection tube includes an outer protective tube and an inner buffer tube. The inner wall of the outer protective tube is provided with a spiral groove, and the outer wall of the inner buffer tube is provided with a protruding buckle that matches the spiral groove. The outer protective tube and the inner buffer tube are detachably connected by the rotational engagement of the spiral groove and the protruding buckle. Both the outer protective tube and the inner buffer tube are made of a blend of chlorinated polyvinyl chloride and polyvinyl chloride. The blended base material contains a combination of rare earth composite stabilizer, aluminum magnesium hydroxide composite flame retardant and red phosphorus flame retardant. The remaining additives are in the mass fraction relative to the blended base material, replacing traditional toxic metal stabilizers and halogen flame retardants. In this design, the outer protective tube and the inner buffer tube are detachably connected through a rotating engagement of spiral grooves and protruding buckles, facilitating the installation, disassembly, and subsequent recycling of the tubes. Both the outer protective tube and the inner buffer tube use a blend of chlorinated polyvinyl chloride and polyvinyl chloride as the core material, combined with a rare earth composite stabilizer, aluminum-magnesium hydroxide composite flame retardant, and red phosphorus flame retardant. This replaces traditional toxic metal stabilizers and halogen flame retardants, reducing the use of toxic and harmful substances, improving the environmental friendliness of the tubes, and simultaneously achieving both stabilization and flame retardant effects. This effectively protects the internal cables from damage caused by the external environment. In the aforementioned environmentally friendly and recyclable CPVC cable protection pipe, chlorinated polyvinyl chloride accounts for 70-85% of the mass of the blended base material, and polyvinyl chloride accounts for 15-30% of the mass of the blended base material. This solution limits the proportions of chlorinated polyvinyl chloride (PVC) and polyvinyl chloride (PVC) in the blended substrate, allowing the two materials to fully utilize their respective characteristics, optimizing the overall performance of the blended substrate, making it more suitable for the use requirements of cable protection pipes, taking into account the molding performance and usage stability of the materials, and providing a basic guarantee for the various performance characteristics of the outer protective pipe and the inner buffer pipe. The aforementioned environmentally friendly recyclable CPVC cable protection pipe contains chlorinated polyvinyl chloride and polyvinyl chloride as a blended base material, with the remaining components being mass fractions relative to the blended base material. Based on this, the raw material formulation includes 70-85% chlorinated polyvinyl chloride, 15-30% polyvinyl chloride, 3-5% rare earth composite stabilizer, 20-25% aluminum-magnesium hydroxide composite flame retardant, 5-8% red phosphorus flame retardant, 10-15% modified nano-calcium carbonate filler, 5-10% TPU elastomer, and 2-3% low molecular weight CPVC processing aids. The solution clearly defines the ratio of the blended base material and additives, with multiple raw materials working synergistically to improve the processing and performance of the raw materials, making them easier to process and shape. At the same time, it further enhances the environmental friendliness and reliability of the materials, ensuring that the outer protective tube and inner buffer tube can meet the usage requirements of cable protection tubes in different scenarios, and improving the overall applicability of the pipes. The aforementioned environmentally friendly recyclable CPVC cable protection pipe has a spiral groove depth of 1.5-2.0mm, a screw pitch of 4-6mm, a raised buckle height of 1.8-2.5mm, and an interference fit clearance of 0.1-0.5mm between the raised buckle and the spiral groove. The design incorporates a reasonable arrangement of spiral grooves and protruding buckles, which enhances the tightness of the connection between the outer protective tube and the inner buffer tube, preventing loosening after connection and ensuring the stability of their fit. This provides better protection for the internal cables without affecting their detachability, facilitating subsequent maintenance and recycling. The aforementioned environmentally friendly recyclable CPVC cable protection pipe contains aluminum-magnesium hydroxide composite flame retardant in a mass ratio of 3-5:1 to red phosphorus flame retardant, with a particle size of 5-15μm. The surface is modified with a silane coupling agent to enhance compatibility with CPVC / PVC blended substrate. In this solution, aluminum magnesium hydroxide composite flame retardant is mixed with red phosphorus flame retardant in a specific ratio, which can improve the flame retardant effect. The modification treatment of silane coupling agent makes the composite flame retardant better integrated with CPVC / PVC blend substrate, avoids the separation of flame retardant and substrate, improves the overall performance of raw materials, and makes the flame retardant performance of outer protective tube and inner buffer tube more stable, while ensuring the integrity of the material and the reliability of use. The aforementioned environmentally friendly recyclable CPVC cable protection pipe, wherein the recycling and reprocessing process of the CPVC cable protection pipe includes the following steps: The first step is recycling and sorting. The recycled outer protective tube, inner buffer tube, and matching CPVC sealing ring are sorted to remove surface dirt, impurities, and non-CPVC foreign objects, ensuring that the purity of the recycled material is not less than 98%. The second step is crushing. The sorted recycled pipes are crushed into uniform particles with a particle size of 5-10mm. During the crushing process, the crushing temperature is controlled to not exceed 60℃ to avoid degradation of the pipe material due to high temperature. The third step is drying. The crushed recycled particles are placed in a hot air dryer and dried for 2-3 hours at 80-90℃ and 1.2-1.5m / s until the moisture content of the recycled particles is less than 0.3% to prevent defects such as bubbles and shrinkage cavities from occurring in subsequent extrusion molding. The fourth step is blending modification. By mass percentage, 50-70% of the recycled particles and 30-50% of the new material are put into a high-speed mixer and mixed at 100-110℃ for 15-20 minutes to ensure that the recycled particles and the new material are evenly dispersed. The fifth step is extrusion molding. Following the above preparation process, the temperature of the extruder feed section is controlled at 160-170℃, the melting section at 175-185℃, and the die head at 180-190℃, and the screw speed is 25-35 r / min. After extrusion molding, the material is cooled, shaped, and then traction-cut to obtain recycled pipes. The recycled pipes have an impact strength of not less than 12MPa, a tensile strength of not less than 45MPa, and a Vicat softening temperature of not less than 90℃. All properties meet the standards for cable protection pipes, and the recycling and reprocessing process does not emit any toxic or harmful substances, achieving environmentally friendly closed-loop utilization. This solution, through a series of recycling and reprocessing steps, enables the effective recycling and reuse of the outer protective tube, inner buffer tube, and matching CPVC sealing ring, reducing resource waste. During the recycling process, temperature and impurities are controlled to avoid material degradation and the influence of impurities, ensuring that the recycled pipes can meet the usage requirements of cable protection pipes. At the same time, the recycling and reprocessing process does not emit toxic or harmful substances, further improving the environmental friendliness of the pipes and realizing the recycling of resources. The aforementioned environmentally friendly recyclable CPVC cable protection pipes have the following characteristics: a Vicat softening temperature of not less than 93℃, an impact strength of not less than 15MPa, a tensile strength of not less than 50MPa, a service life of not less than 50 years, a quality recovery rate of not less than 90%, and a purity of not less than 98% for recycled materials. This solution ensures the various performance characteristics of CPVC cable protection pipes, giving the pipes excellent high-temperature resistance, impact resistance, and tensile strength. This allows them to adapt to different usage environments, extend the service life of the pipes, improve the quality recycling rate of the pipes, reduce resource consumption and environmental impact caused by pipe replacement, and provide long-term and stable protection for cables. The aforementioned environmentally friendly recyclable CPVC cable protection pipe has an inner buffer tube with uniformly arranged annular buffer ridges on its inner wall. The height of the annular buffer ridges is 0.8-1.2mm, the width is 1.0-1.5mm, and the spacing between adjacent annular buffer ridges is 3-5mm. The annular buffer ridges and the inner buffer tube are integrally extruded and molded to reduce the friction between the cable and the inner wall of the inner buffer tube, while enhancing the buffering and shock absorption performance and protecting the cable insulation layer. The annular buffer ridges on the inner wall of the inner buffer tube in this design reduce friction between the cable and the inner wall of the inner buffer tube, preventing wear on the cable insulation layer. At the same time, they can also play a buffering and shock-absorbing role, reducing the impact of external vibrations on the cable and better protecting it. The annular buffer ridges are integrally extruded with the inner buffer tube, which can ensure the connection stability between the annular buffer ridges and the inner buffer tube, prevent them from falling off, and improve the reliability of the protection. The aforementioned environmentally friendly recyclable CPVC cable protection pipe has an outer protective pipe with a uniform coating of 0.3-0.5mm thickness on its outer wall. This environmentally friendly anti-aging coating is a composite coating of polysiloxane and nano-titanium dioxide, with nano-titanium dioxide accounting for 8-12% of the mass. This coating is used to improve the outer protective pipe's resistance to ultraviolet rays and anti-aging properties, slow down the aging rate of the pipe, and further extend the service life of the pipe. Moreover, this anti-aging coating can be recycled and reprocessed together with the pipe. The coating has good compatibility with CPVC / PVC blended substrate and does not affect the mechanical and flame retardant properties of the recycled material. The environmentally friendly anti-aging coating applied to the outer wall of the outer protective pipe in this solution can enhance the outer protective pipe's resistance to ultraviolet rays and anti-aging capabilities, slow down the aging rate of the outer protective pipe, and thus extend the overall service life of the pipe. This anti-aging coating can be recycled and reprocessed together with the pipe without affecting the performance of the recycled material, without compromising the recyclability of the pipe, and further improving the environmental performance of the pipe. This invention also provides a method for preparing an environmentally friendly, recyclable CPVC cable protection pipe, comprising the following steps: The first step is raw material preparation. Weigh each raw material according to the above-mentioned mass ratio and relative mass fraction of the blended base material. Among them, the aluminum hydroxide magnesium composite flame retardant and the red phosphorus flame retardant are mixed in the above-mentioned proportion and modified by silane coupling agent. The second step is mixing and plasticizing. Chlorinated polyvinyl chloride, polyvinyl chloride, rare earth composite stabilizer, modified composite flame retardant, modified nano calcium carbonate filler, TPU elastomer and low molecular weight CPVC processing aid are put into a high-speed mixer and mixed at 105-115℃ for 20-25 minutes until uniform. Then it is fed into a twin-screw plasticizer and plasticized at 170-180℃ for 8-12 minutes to obtain a uniform plasticized material. The third step is layered extrusion. The plasticized material is fed into two extruders. One extruder extrudes the outer protective tube, simultaneously forming a spiral groove during the extrusion process. The extrusion temperature is controlled at 165-175℃ and the screw speed at 30-40 r / min. The other extruder extrudes the inner buffer tube, simultaneously forming a protruding buckle during the extrusion process. The extrusion temperature is controlled at 160-170℃ and the screw speed at 35-45 r / min. The fourth step is assembly. The extruded inner buffer tube and outer protective tube are rotated together by spiral grooves and protruding buckles to achieve detachable assembly. During the assembly process, the rotation force is controlled at 5-8 N·m to ensure a tight connection without loosening. The fifth step is post-processing. The assembled pipes are cooled and shaped at a temperature of 20-30℃ for 15-20 minutes. After shaping, the two ends of the pipes are cut and trimmed to remove burrs. An environmentally friendly anti-aging coating is then applied to the outer wall of the outer protective pipe. After the coating dries, an adhesion test is conducted. The adhesion level should be no less than level 1. After the coating dries, a performance test is performed. Once the coating passes the test, it can be packaged and stored. This solution, through the orderly coordination of each preparation step, can accurately produce environmentally friendly and recyclable CPVC cable protection pipes that meet the requirements, ensuring that the structure and performance of the outer protective pipe, inner buffer pipe, and each component meet the usage requirements; the assembly process can ensure that each component fits tightly, and subsequent processing can improve the appearance and performance of the pipe. The entire preparation process is in line with the concept of environmental protection, ensuring the environmental friendliness and recyclability of the pipe, and realizing the stable mass production of the pipe. The present invention has the following beneficial effects: The double-layer structure design of the outer protective tube and the inner buffer tube, combined with the annular buffer ridge, not only protects against external impacts, corrosion, and UV radiation through the outer protective tube, but also reduces friction between the cable and the inner wall of the tube through the inner buffer tube and the annular buffer ridge, mitigating the impact of external vibrations. This dual protection effectively protects the cable insulation layer and prevents cable damage. The rotating engagement of the spiral groove and the raised buckle allows for a detachable connection between the outer protective tube and the inner buffer tube, simplifying the installation and maintenance process of the tube and facilitating disassembly and recycling, thus promoting resource recycling. The outer protective tube and the inner buffer tube use a blend of chlorinated polyvinyl chloride and polyvinyl chloride as the base material, combined with a combination of rare earth composite stabilizers, aluminum magnesium hydroxide composite flame retardants, and red phosphorus flame retardants. This replaces traditional toxic metal stabilizers and halogen flame retardants, reducing the use and emission of toxic and harmful substances, improving the environmental friendliness of the tube, and enhancing the stability and flame retardant properties of the material. This ensures long-term stable use of the tube, effectively preventing the spread of flames and protecting cable safety. The composite flame retardant is modified with a silane coupling agent, improving its compatibility with the blended substrate, preventing flame retardant detachment, and further optimizing the overall performance of the pipe. The environmentally friendly anti-aging coating on the outer wall of the outer protective pipe enhances its UV resistance and anti-aging capabilities, slowing down the aging process and extending the overall service life of the pipe. This coating can be recycled and reprocessed along with the pipe without affecting the mechanical and flame-retardant properties of the recycled material. A reasonable manufacturing process ensures stable molding quality for each component. Layered extrusion simultaneously molds each structural component, reducing subsequent processing steps, improving production efficiency, and ensuring accurate pipe dimensions and tight connections. The recycling and reprocessing process enables efficient recycling and reuse of the outer protective pipe, inner buffer pipe, and supporting components, reducing resource waste. The recycled pipe meets usage standards, and the entire recycling process emits no toxic or harmful substances, achieving environmentally friendly closed-loop utilization. In summary, this environmentally friendly recyclable CPVC cable protection pipe combines environmental friendliness, practicality, and reliability. It is easy to install and maintain, meeting the cable protection needs of different scenarios and solving many shortcomings of existing CPVC cable protection pipes. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the structure of the environmentally friendly recyclable CPVC cable protection pipe provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the exploded structure of an environmentally friendly recyclable CPVC cable protection pipe provided in an embodiment of the present invention; Figure 3 A comparison chart of Vicat softening temperatures; Figure 4 This is a comparison chart of impact resistance strength; Figure 5 This is a comparison chart of tensile strength.

[0007] In the attached image: 1. Outer protective tube; 101. Spiral groove; 2. Inner buffer tube; 201. Raised buckle; 202. Annular buffer ridge. Detailed Implementation

[0008] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0009] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0010] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0011] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0012] Reference Figure 1-5 ,in, Figure 3 The Vicat softening temperatures of Examples 1-3 were shown to be 95°C, 93°C, and 97°C, respectively, showing a trend of first decreasing and then increasing. Figure 4 Example 3 showed the best performance (17.5 MPa), while Example 2 showed the lowest (15.0 MPa). Figure 5 Example 3 shows a strength of 54.8 MPa, and Example 2 shows a strength of 50.0 MPa; this specific implementation provides the following three examples.

[0013] Example 1 I. Technical Solution The environmentally friendly recyclable CPVC cable protection pipe of this embodiment includes an outer protective pipe 1 and an inner buffer pipe 2. The inner wall of the outer protective pipe 1 is provided with a spiral groove 101, and the outer wall of the inner buffer pipe 2 is provided with a protruding buckle 201 that matches the spiral groove 101. The outer protective pipe 1 and the inner buffer pipe 2 are detachably connected by the rotational engagement of the spiral groove 101 and the protruding buckle 201. Both the outer protective tube 1 and the inner buffer tube 2 are made of a blend of chlorinated polyvinyl chloride (PVC) and polyvinyl chloride (PVC). The remaining components are mass fractions relative to the blended base material. Based on this, the raw material formula is: 78% chlorinated PVC, 22% PVC, 4% rare earth composite stabilizer, 22% aluminum-magnesium hydroxide composite flame retardant, 6% red phosphorus flame retardant, 12% modified nano-calcium carbonate filler, 8% TPU elastomer, and 2.5% low molecular weight CPVC processing aid. The mass ratio of aluminum-magnesium hydroxide composite flame retardant to red phosphorus flame retardant is 3.7:1, the particle size of the composite flame retardant is 10 μm, and its surface is modified with a silane coupling agent. The spiral groove 101 has a depth of 1.8 mm and a pitch of 5 mm. The raised buckle 201 has a height of 2.2 mm, and the interference fit clearance between the raised buckle 201 and the spiral groove 101 is 0.2 mm. The inner wall of the inner buffer tube 2 is uniformly provided with annular buffer ridges 202. The height of the annular buffer ridges 202 is 1.0 mm, the width is 1.2 mm, and the spacing between adjacent annular buffer ridges 202 is 4 mm. The annular buffer ridges 202 and the inner buffer tube 2 are integrally extruded. The outer wall of the outer protective tube 1 is uniformly coated with an environmentally friendly anti-aging coating with a thickness of 0.4 mm. This environmentally friendly anti-aging coating is a composite coating of polysiloxane and nano-titanium dioxide, with the nano-titanium dioxide accounting for 10% of the mass. The preparation method of this CPVC cable protection pipe includes the following steps: First, raw material preparation: Weigh each raw material according to the above-mentioned mass ratio and relative mass fraction of the blended substrate. The aluminum hydroxide magnesium composite flame retardant and red phosphorus flame retardant are mixed in a ratio of 3.7:1 and modified with a silane coupling agent. Second, mixing and plasticizing: Chlorinated polyvinyl chloride, polyvinyl chloride, rare earth composite stabilizer, modified composite flame retardant, modified nano-calcium carbonate filler, TPU elastomer, and low molecular weight CPVC processing aids are added to a high-speed mixer and mixed at 110℃ for 22 minutes until homogeneous. Then, the mixture is fed into a twin-screw plasticizer and plasticized at 175℃ for 10 minutes to obtain a homogeneous plasticized material. Third, layered extrusion: The plasticized material is fed into two extruders. One extruder extrudes the outer protective pipe 1, and during extrusion, a spiral groove 101 is formed simultaneously. The extrusion temperature is controlled. The temperature is 170℃ and the screw speed is 35r / min; another machine extrudes the inner buffer tube 2, and the protruding buckle 201 is formed simultaneously during the extrusion process. The extrusion temperature is controlled at 165℃ and the screw speed is 40r / min; the fourth step is assembly. The extruded inner buffer tube 2 and the outer protective tube 1 are rotated and engaged with the protruding buckle 201 through the spiral groove 101 to achieve detachable assembly. During the assembly process, the rotation force is controlled at 6.5N·m to ensure a tight connection without loosening; the fifth step is subsequent processing. The assembled tube is cooled and shaped at a temperature of 25℃ for 18min. After shaping, the two ends of the tube are cut and trimmed to remove burrs. Then, an environmentally friendly anti-aging coating is applied to the outer wall of the outer protective tube 1. After the coating dries, the adhesion level is tested and found to be level 0. After the coating dries, the performance is tested and qualified before packaging and warehousing. The recycling and reprocessing process of this CPVC cable protection pipe includes the following steps: First, sorting and separating the recycled outer protective pipe 1, inner buffer pipe 2, and matching CPVC sealing ring. This removes surface-attached dirt, impurities, and non-CPVC materials, ensuring the purity of the recycled material is not less than 98%. Second, crushing the sorted recycled pipe material into uniform particles with a diameter of 8mm. During crushing, the crushing temperature is controlled to not exceed 60℃ to prevent degradation of the pipe material due to high temperatures. Third, drying the crushed recycled particles in a hot air dryer at 85℃ and an air velocity of 1.3m / s. The recycled particles are dried for 2.5 hours under certain conditions until the moisture content is below 0.3% to prevent air bubbles and shrinkage defects in subsequent extrusion molding. The fourth step is blending modification. By mass percentage, 60% of the recycled particles and 40% of the new material are put into a high-speed mixer and mixed at 105°C for 18 minutes to ensure that the recycled particles and the new material are evenly dispersed. The fifth step is extrusion molding. Using the relevant parameters in the above preparation process, the temperature of the extruder feed section is controlled at 165°C, the melting section at 180°C, and the die head at 185°C. The screw speed is 30 r / min. After extrusion molding, the recycled pipe is obtained by cooling and shaping and traction cutting. II. Working Principle Structural Working Principle: The outer protective tube 1 primarily provides external protection, resisting external impacts, corrosion, and UV erosion. Its environmentally friendly anti-aging coating further enhances its anti-aging capabilities, delaying tube aging. The inner buffer tube 2 directly contacts the cable. The annular buffer ridge 202 on its inner wall reduces friction between the cable and the inner buffer tube 2, mitigating the impact of external vibrations on the cable and preventing damage to the cable insulation. The outer protective tube 1 and inner buffer tube 2 are detachably connected via a rotating engagement of a spiral groove 101 and a raised buckle 201. During rotational assembly, the raised buckle 201 engages with the spiral groove 101 and rotates along the groove, achieving a tight connection through an interference fit. Disassembly is achieved by rotating in the opposite direction, facilitating installation, maintenance, and recycling. In terms of materials, a blend of chlorinated polyvinyl chloride and polyvinyl chloride is combined with a rare earth composite stabilizer to ensure material stability. Aluminum hydroxide magnesium composite flame retardant and red phosphorus flame retardant work synergistically to form a highly efficient flame-retardant system, preventing flame spread and protecting cable safety. Preparation and Recycling Working Principle: In the preparation process, the raw materials are first mixed and plasticized to ensure uniform fusion and improve the processing performance of the plasticized material. Then, the outer protective tube 1 and the inner buffer tube 2 are formed by layered extrusion, while the spiral groove 101, the raised buckle 201, and the annular buffer ridge 202 are formed simultaneously to ensure the integrity of each component structure. Subsequently, qualified pipes are obtained through assembly, cooling, coating and other steps. In the recycling and reprocessing process, impurities are first removed by sorting to ensure the purity of the recycled material. Crushing and drying processes are used to avoid material degradation and molding defects. Blending and modification are used to ensure uniform fusion of recycled particles and new materials. Finally, recycled pipes are obtained through extrusion molding, realizing resource recycling. The entire process has no emissions of toxic or harmful substances and meets environmental protection requirements. III. Experimental Data The performance of the new CPVC cable protection pipe and the recycled pipe prepared in this embodiment was tested, and the test results are as follows: 1. New pipe performance: Vicat softening temperature 95℃, impact strength 16.2MPa, tensile strength 52.3MPa. After 1000h UV aging test, the tensile strength retention rate is 92.5%, the impact strength retention rate is 91.8%, the service life can reach 55 years, the quality recovery rate is 93%, and the purity of recycled material is 98.5%. 2. Performance of recycled pipe: Impact strength 13.5MPa, tensile strength 47.8MPa, Vicat softening temperature 92℃, after 500h ultraviolet aging test, tensile strength retention rate 89.6%, impact strength retention rate 88.9%, all performance meet the standards for cable protection pipes. 3. Connection performance: After the outer protective tube 1 and the inner buffer tube 2 are connected, there is no loosening or separation under an external pressure of 1.5MPa. The rotational disassembly force is 7.2N·m. No parts are damaged after disassembly, and they can be reassembled and used repeatedly. 4. Environmental performance: The material contains no toxic metal stabilizers or halogen flame retardants, and there is no emission of toxic or harmful gases during combustion. During the recycling and reprocessing process, there is no discharge of wastewater, waste gas, or waste residue. 5. Coating performance: The anti-aging coating has an adhesion rating of 0. After 1000 hours of UV aging test, the coating showed no peeling or chalking. IV. Technical Effects The double-layer structure design of the outer protective tube 1 and the inner buffer tube 2, combined with the annular buffer ridge 202, not only resists external impacts and corrosion, but also reduces friction between the cable and the inner wall of the tube, mitigating the effects of vibration and effectively protecting the cable insulation layer to prevent cable damage. The rotating engagement of the spiral groove 101 and the protruding buckle 201 enables detachable connection of the tube, facilitating installation, maintenance, and recycling, and improving ease of use. The ratio of the blended base material and additives is clearly defined, especially the modified composite flame retardant, which has good compatibility with the base material, improving the flame retardant performance and overall stability of the tube, while replacing traditional toxic additives. Additives reduce the use of toxic and harmful substances, improving the environmental friendliness of the pipes; the environmentally friendly anti-aging coating on the outer wall of the outer protective pipe effectively enhances the pipe's resistance to ultraviolet rays and aging, slows down the aging process, and extends the service life of the pipes; the rational design of the recycling and reprocessing process enables efficient recycling and reuse of the pipes, reducing resource waste, and the performance of the recycled pipes meets the usage standards. The entire recycling process has no emissions of toxic and harmful substances, further improving the environmental protection effect; the coordinated steps of the preparation method ensure stable pipe forming quality and complete component structure, meeting the cable protection needs in different scenarios. Example 2 I. Technical Solution The environmentally friendly recyclable CPVC cable protection pipe of this embodiment includes an outer protective pipe 1 and an inner buffer pipe 2. The inner wall of the outer protective pipe 1 is provided with a spiral groove 101, and the outer wall of the inner buffer pipe 2 is provided with a protruding buckle 201 that matches the spiral groove 101. The outer protective pipe 1 and the inner buffer pipe 2 are detachably connected by the rotational engagement of the spiral groove 101 and the protruding buckle 201. Both the outer protective tube 1 and the inner buffer tube 2 are made of a blend of chlorinated polyvinyl chloride (PVC) and polyvinyl chloride (PVC). The remaining components are mass fractions relative to the blended base material. Based on this, the raw material formula is: 70% chlorinated PVC, 30% PVC, 3% rare earth composite stabilizer, 20% aluminum-magnesium hydroxide composite flame retardant, 5% red phosphorus flame retardant, 10% modified nano-calcium carbonate filler, 5% TPU elastomer, and 2% low molecular weight CPVC processing aid. The mass ratio of aluminum-magnesium hydroxide composite flame retardant to red phosphorus flame retardant is 4:1. The particle size of the composite flame retardant is 5 μm, and its surface is modified with a silane coupling agent. The spiral groove 101 has a depth of 1.5mm and a pitch of 4mm. The raised buckle 201 has a height of 1.8mm, and the interference fit clearance between the raised buckle 201 and the spiral groove 101 is 0.1mm. The inner wall of the inner buffer tube 2 is uniformly provided with annular buffer ridges 202. The height of the annular buffer ridges 202 is 0.8mm, the width is 1.0mm, and the spacing between adjacent annular buffer ridges 202 is 3mm. The annular buffer ridges 202 and the inner buffer tube 2 are integrally extruded. The outer wall of the outer protective tube 1 is uniformly coated with a 0.3mm thick environmentally friendly anti-aging coating. This environmentally friendly anti-aging coating is a composite coating of polysiloxane and nano-titanium dioxide, with nano-titanium dioxide accounting for 8% of the total mass. The preparation method of this CPVC cable protection pipe includes the following steps: First, raw material preparation: Weigh each raw material according to the above-mentioned mass ratio and relative mass fraction of the blended substrate. The aluminum hydroxide magnesium composite flame retardant and red phosphorus flame retardant are mixed in a 4:1 ratio and modified with a silane coupling agent. Second, mixing and plasticizing: Chlorinated polyvinyl chloride, polyvinyl chloride, rare earth composite stabilizer, modified composite flame retardant, modified nano-calcium carbonate filler, TPU elastomer, and low molecular weight CPVC processing aids are added to a high-speed mixer and mixed at 105℃ for 20 minutes until homogeneous. Then, the mixture is fed into a twin-screw plasticizer and plasticized at 170℃ for 8 minutes to obtain a homogeneous plasticized material. Third, layered extrusion: The plasticized material is fed into two extruders. One extruder extrudes the outer protective pipe 1, and during extrusion, a spiral groove 101 is formed simultaneously. The extrusion temperature is controlled. The extrusion temperature is 165℃ and the screw speed is 30r / min. Another machine extrudes the inner buffer tube 2, and the protruding buckle 201 is formed simultaneously during the extrusion process. The extrusion temperature is controlled at 160℃ and the screw speed is 35r / min. The fourth step is assembly. The extruded inner buffer tube 2 and the outer protective tube 1 are rotated and engaged with the protruding buckle 201 through the spiral groove 101 to achieve detachable assembly. During the assembly process, the rotation force is controlled at 5N·m to ensure a tight connection without loosening. The fifth step is subsequent processing. The assembled tube is cooled and shaped at a temperature of 20℃ for 15min. After shaping, the two ends of the tube are cut and trimmed to remove burrs. Then, an environmentally friendly anti-aging coating is applied to the outer wall of the outer protective tube 1. After the coating dries, the adhesion level is tested and it is grade 1. After the coating dries, the performance is tested and it is qualified before being packaged and stored. The recycling and reprocessing process of this CPVC cable protection pipe includes the following steps: First, sorting and separating the recycled outer protective pipe 1, inner buffer pipe 2, and matching CPVC sealing rings to remove surface-attached dirt, impurities, and non-CPVC materials, ensuring the purity of the recycled material is not less than 98%. Second, crushing the sorted recycled pipe material into uniform particles with a particle size of 5mm. During crushing, the crushing temperature is controlled to not exceed 60℃ to prevent degradation of the pipe material due to high temperatures. Third, drying the crushed recycled particles in a hot air dryer at 80℃ and an air velocity of 1.2m / s. Dry for 2 hours under conditions of / s until the moisture content of the recycled particles is below 0.3% to prevent defects such as bubbles and shrinkage cavities in subsequent extrusion molding; Fourth step, blending modification: by mass percentage, 50% of the recycled particles and 50% of the new material are put into a high-speed mixer and mixed at 100℃ for 15 minutes to ensure that the recycled particles and the new material are evenly dispersed; Fifth step, extrusion molding: using the relevant parameters in the above preparation process, the temperature of the extruder feed section is controlled at 160℃, the melting section at 175℃, the die head section at 180℃, and the screw speed at 25r / min. After extrusion molding, the recycled pipe is obtained by cooling and shaping and traction cutting. II. Working Principle Structural Working Principle: The outer protective tube 1 serves as the outer protective structure of the pipe, effectively resisting external mechanical impacts, soil corrosion, and ultraviolet radiation. Its environmentally friendly anti-aging coating further enhances anti-aging performance and reduces environmental damage to the pipe. The inner buffer tube 2 is fitted to the cable, and the annular buffer ridge 202 on the inner wall reduces the direct contact area between the cable and the inner wall of the pipe, reducing friction loss. At the same time, when subjected to external vibration, the annular buffer ridge 202 can undergo slight deformation to absorb vibration energy and protect the cable insulation layer from damage. The outer protective tube 1 and the inner buffer tube 2 are detachably connected by the rotational engagement of the spiral groove 101 and the protruding buckle 201. The interference fit clearance ensures a tight connection and prevents loosening during use. Reverse rotation can achieve separation, facilitating later maintenance and pipe recycling. In terms of materials, chlorinated polyvinyl chloride and polyvinyl chloride are blended in a specific ratio as the base material, taking into account both the rigidity and toughness of the material. Rare earth composite stabilizers replace traditional toxic metal stabilizers to improve the stability of the material. Aluminum hydroxide magnesium composite flame retardant and red phosphorus flame retardant are mixed in a 4:1 ratio and modified with silane coupling agent to integrate more tightly with the base material, forming a reliable flame retardant system to prevent the cable from being damaged by fire. Preparation and Recycling Working Principle: During the preparation process, each raw material is accurately weighed and pretreated to ensure the modification effect of the composite flame retardant. Then, through high-speed mixing and twin-screw plasticizing, the raw materials are fully integrated to form a uniform plasticized material, ensuring the stability of subsequent extrusion molding. The layered extrusion process separately forms the outer protective tube 1 and the inner buffer tube 2, and simultaneously forms each structural component, reducing subsequent processing steps and improving production efficiency. During assembly, the rotation force is controlled to ensure tight connection and no damage to components. Subsequent cooling, trimming, and coating steps further improve the appearance and performance of the pipe. During recycling and reprocessing, impurities are first removed by sorting to ensure the purity of the recycled material. Low-temperature crushing and drying treatment prevent material degradation. The recycled particles are blended and modified with virgin materials in proportion to ensure the stability of the recycled material's performance. Then, the recycled pipe is obtained through extrusion molding, realizing the recycling of resources. The entire process has no emissions of toxic or harmful substances, which is in line with environmental protection principles. III. Experimental Data The performance of the new CPVC cable protection pipe and the recycled pipe prepared in this embodiment was tested, and the test results are as follows: 1. New pipe performance: Vicat softening temperature 93℃, impact strength 15.0MPa, tensile strength 50.0MPa; after 1000h UV aging test, tensile strength retention rate is 90.2%, impact strength retention rate is 89.5%, service life can reach 50 years, quality recovery rate is 90%, and recycled material purity is 98.2%; 2. Performance of recycled pipe: Impact strength 12.0MPa, tensile strength 45.0MPa, Vicat softening temperature 90℃, after 500h ultraviolet aging test, tensile strength retention rate 88.3%, impact strength retention rate 87.6%, all performance meet the standards for cable protection pipes. 3. Connection performance: After the outer protective tube 1 and the inner buffer tube 2 are connected, there is no loosening or separation under an external pressure of 1.2MPa. The rotational disassembly force is 6.0N·m. After disassembly, the parts are undamaged and can be reassembled and used repeatedly. 4. Environmental performance: No toxic metal stabilizers or halogen flame retardants were detected in the material. No toxic or harmful gases are released during combustion. During recycling and reprocessing, the discharge of wastewater, waste gas, and waste residue is zero. 5. Coating performance: The anti-aging coating has an adhesion rating of Grade 1. After 1000 hours of UV aging test, the coating did not peel off, with only slight chalking at the edges. IV. Technical Effects The double-layer structure design clearly defines the functions of the outer protective tube 1 and the inner buffer tube 2. The outer protective tube 1 resists various external damages, while the inner buffer tube 2 protects the cable from friction and vibration. This dual protection enhances the reliability of cable protection. The rotational engagement of the spiral groove 101 and the protruding buckle 201 enables detachable connection of the tube, simplifying installation and maintenance processes and facilitating tube recycling. The ratio of the blended base material to the additives is clear, with reasonable proportions of each raw material. The modified composite flame retardant has good compatibility with the base material, not only improving the flame retardant performance and structural stability of the tube but also reducing the use of toxic and harmful substances by replacing traditional toxic additives. Emissions are reduced, improving the environmental friendliness of the pipes; the environmentally friendly anti-aging coating on the outer wall of the outer protective pipe 1 effectively enhances the pipe's UV resistance, delays pipe aging, and ensures long-term stable use, reaching the expected service life; the recycling and reprocessing process is reasonable, achieving efficient recycling and reuse of the pipes through sorting, low-temperature crushing, drying, and blending modification, reducing resource waste, and ensuring that the performance of the recycled pipes meets the usage standards, with no environmental pollution during the recycling process, further enhancing the environmental protection effect; the preparation method is simple, with reasonable parameters in each step, enabling stable batch production of the pipes, ensuring uniform pipe quality, and meeting the needs of cable protection in basic scenarios. Example 3 I. Technical Solution The environmentally friendly recyclable CPVC cable protection pipe of this embodiment includes an outer protective pipe 1 and an inner buffer pipe 2. The inner wall of the outer protective pipe 1 is provided with a spiral groove 101, and the outer wall of the inner buffer pipe 2 is provided with a protruding buckle 201 that matches the spiral groove 101. The outer protective pipe 1 and the inner buffer pipe 2 are detachably connected by the rotational engagement of the spiral groove 101 and the protruding buckle 201. Both the outer protective tube 1 and the inner buffer tube 2 are made of a blend of chlorinated polyvinyl chloride (PVC) and polyvinyl chloride (PVC). The remaining components are mass fractions relative to the blended base material. Based on this, the raw material formula is: 85% chlorinated PVC, 15% PVC, 5% rare earth composite stabilizer, 25% aluminum-magnesium hydroxide composite flame retardant, 8% red phosphorus flame retardant, 15% modified nano-calcium carbonate filler, 10% TPU elastomer, and 3% low molecular weight CPVC processing aid. The mass ratio of aluminum-magnesium hydroxide composite flame retardant to red phosphorus flame retardant is 3:1. The particle size of the composite flame retardant is 15 μm, and its surface is modified with a silane coupling agent. The spiral groove 101 has a depth of 2.0 mm and a pitch of 6 mm. The raised buckle 201 has a height of 2.5 mm, and the interference fit clearance between the raised buckle 201 and the spiral groove 101 is 0.3 mm. The inner wall of the inner buffer tube 2 is uniformly provided with annular buffer ridges 202. The height of the annular buffer ridges 202 is 1.2 mm, the width is 1.5 mm, and the spacing between adjacent annular buffer ridges 202 is 5 mm. The annular buffer ridges 202 and the inner buffer tube 2 are integrally extruded. The outer wall of the outer protective tube 1 is uniformly coated with a 0.5 mm thick environmentally friendly anti-aging coating. This environmentally friendly anti-aging coating is a composite coating of polysiloxane and nano-titanium dioxide, with nano-titanium dioxide accounting for 12% of the mass. The preparation method of this CPVC cable protection pipe includes the following steps: First, raw material preparation: Weigh each raw material according to the above-mentioned mass ratio and relative mass fraction of the blended base material. The aluminum hydroxide magnesium composite flame retardant and red phosphorus flame retardant are mixed in a 3:1 ratio and modified with a silane coupling agent. Second, mixing and plasticizing: Chlorinated polyvinyl chloride, polyvinyl chloride, rare earth composite stabilizer, modified composite flame retardant, modified nano-calcium carbonate filler, TPU elastomer, and low molecular weight CPVC processing aids are added to a high-speed mixer and mixed at 115℃ for 25 minutes until homogeneous. Then, the mixture is fed into a twin-screw plasticizer and plasticized at 180℃ for 12 minutes to obtain a homogeneous plasticized material. Third, layered extrusion: The plasticized material is fed into two extruders. One extruder extrudes the outer protective pipe 1, and during extrusion, a spiral groove 101 is formed simultaneously. The extrusion temperature is controlled. The temperature is 175℃ and the screw speed is 40r / min; another machine extrudes the inner buffer tube 2, and the protruding buckle 201 is formed simultaneously during the extrusion process. The extrusion temperature is controlled at 170℃ and the screw speed is 45r / min; the fourth step is assembly. The extruded inner buffer tube 2 and the outer protective tube 1 are rotated and engaged with the protruding buckle 201 through the spiral groove 101 to achieve detachable assembly. During the assembly process, the rotation force is controlled at 8N·m to ensure a tight connection without loosening; the fifth step is subsequent processing. The assembled tube is cooled and shaped at a temperature of 30℃ for 20min. After shaping, the two ends of the tube are cut and trimmed to remove burrs. Then, an environmentally friendly anti-aging coating is applied to the outer wall of the outer protective tube 1. After the coating dries, the adhesion level is tested and found to be level 0. After the coating dries, the performance is tested and qualified before packaging and warehousing. The recycling and reprocessing process of this CPVC cable protection pipe includes the following steps: First, sorting and recycling: The recycled outer protective pipe 1, inner buffer pipe 2, and matching CPVC sealing ring are sorted to remove surface-attached dirt, impurities, and non-CPVC materials, ensuring the purity of the recycled material is not less than 98%. Second, crushing: The sorted recycled pipe material is crushed into uniform particles with a particle size of 10mm. During the crushing process, the crushing temperature is controlled to not exceed 60℃ to prevent degradation of the pipe material due to high temperatures. Third, drying: The crushed recycled particles are placed in a hot air dryer at 90℃ and an air velocity of 1.5m. Dry for 3 hours under conditions of / s until the moisture content of the recycled particles is below 0.3% to prevent defects such as bubbles and shrinkage cavities in subsequent extrusion molding; Fourth step, blending modification: by mass percentage, 70% of the recycled particles and 30% of the new material are put into a high-speed mixer and mixed at 110℃ for 20 minutes to ensure that the recycled particles and the new material are evenly dispersed; Fifth step, extrusion molding: using the relevant parameters in the above preparation process, the temperature of the extruder feed section is controlled at 170℃, the melting section at 185℃, the die head section at 190℃, and the screw speed at 35r / min. After extrusion molding, the recycled pipe is obtained by cooling and shaping and traction cutting.

[0014] II. Working Principle Structural Working Principle: The outer protective tube 1 uses a blended base material with a high proportion of chlorinated polyvinyl chloride, which is more rigid and can effectively resist strong external impacts, severe corrosion, and long-term ultraviolet radiation. Its thicker environmentally friendly anti-aging coating further enhances anti-aging performance, slows down the aging rate of the tube, and extends its service life. The inner buffer tube 2 has a larger height and width of annular buffer ridges 202 on its inner wall, which can better reduce the friction between the cable and the inner wall of the tube, and at the same time has stronger buffering and shock absorption capabilities, which can adapt to the use scenarios with large vibration amplitudes and effectively protect the cable insulation layer. The outer protective tube 1 and the inner buffer tube 2 are detachably connected by the rotational engagement of the spiral groove 101 and the protruding buckle 201. The larger interference fit clearance ensures a tighter connection, can withstand greater external pressure, and avoids loosening of the connection. It can be easily separated by rotating in the opposite direction, which is convenient for installation, maintenance and recycling. In terms of materials, a high proportion of chlorinated polyvinyl chloride enhances the rigidity of the pipe, rare earth composite stabilizers ensure long-term material stability, and aluminum hydroxide magnesium composite flame retardant is mixed with red phosphorus flame retardant in a 3:1 ratio for better flame retardant effect. After modification with silane coupling agent, it is more fully integrated with the substrate, avoiding flame retardant detachment and ensuring stable flame retardant performance.

[0015] Preparation and Recycling Working Principle: During the preparation process, the uniformity and processing performance of the plasticized material are improved by adjusting the raw material ratio and processing parameters. It is adapted to the blended base material with a high proportion of chlorinated polyvinyl chloride. During layered extrusion, a higher extrusion temperature and screw speed are controlled to ensure that the outer protective tube 1, inner buffer tube 2, and all structural components are formed completely and dimensionally accurate. During assembly, a larger rotational force is controlled to ensure tight connection. Subsequent cooling, trimming, and coating steps further optimize the appearance and performance of the pipe. During recycling and reprocessing, the larger crushed particle size can reduce material loss during crushing. The higher temperature and air velocity drying treatment can remove moisture from the recycled particles more quickly. The recycled particles are blended and modified with virgin materials in a high proportion to ensure the stability of the recycled material performance. The higher extrusion temperature and screw speed are adapted to the extrusion molding of high proportion recycled particles, realizing the efficient recycling of resources. Moreover, the entire recycling process has no emissions of toxic or harmful substances, which meets environmental protection requirements.

[0016] III. Experimental Data The performance of the new CPVC cable protection pipe and the recycled pipe prepared in this embodiment was tested, and the test results are as follows: 1. New pipe performance: Vicat softening temperature 97℃, impact strength 17.5MPa, tensile strength 54.8MPa, after 1000h UV aging test, tensile strength retention rate 94.7%, impact strength retention rate 93.9%, service life up to 60 years, quality recovery rate 95%; 2. Performance of recycled pipe: Impact strength 14.2MPa, tensile strength 48.5MPa, Vicat softening temperature 91℃, after 500h ultraviolet aging test, tensile strength retention rate 91.2% and impact strength retention rate 90.5%, all performance meet the standards for cable protection pipes. 3. Connection performance: After the outer protective tube 1 and the inner buffer tube 2 are connected, there is no loosening or separation under an external pressure of 2.0MPa. The rotational disassembly force is 8.5N·m. After disassembly, the parts are intact and can be reassembled and used repeatedly. 4. Environmental performance: The material contains no toxic metal stabilizers or halogen flame retardants. The emission of toxic and harmful gases during combustion is far below the industry standard. During the recycling and reprocessing process, there is no wastewater, waste gas, or waste residue discharge. The purity of the recycled material can reach 98.8%.

[0017] IV. Technical Effects The outer protective tube 1 uses a blended base material with a high proportion of chlorinated polyvinyl chloride, resulting in stronger rigidity and corrosion resistance. Combined with a thicker environmentally friendly anti-aging coating, it can adapt to harsher operating environments, effectively resisting strong external impacts, severe corrosion, and prolonged ultraviolet radiation, thus delaying pipe aging and significantly extending its service life. The inner buffer tube 2 features a larger annular buffer ridge 202 on its inner wall, providing superior buffering, shock absorption, and anti-friction effects. This allows it to adapt to scenarios with large vibration amplitudes, better protecting the cable insulation layer and preventing damage from friction or vibration. The optimized structural parameters of the spiral groove 101 and the raised buckle 201 result in a larger interference fit clearance and a tighter connection, enabling it to withstand greater external pressure and preventing loosening during use. This also does not affect its detachability, facilitating installation, maintenance, and recycling. The blended base material and... The additives are formulated as relative mass fractions. The high proportion of flame retardants and modification treatments in the formula enhances the flame retardant properties of the pipes, effectively preventing flame spread and protecting cable safety. The use of rare earth composite stabilizers and environmentally friendly raw materials further improves the environmental friendliness of the pipes, reducing the use and emission of toxic and harmful substances. In the recycling and reprocessing process, a high proportion of recycled particles are blended with virgin materials to achieve efficient recycling and reuse of resources, reducing resource waste. The recycled pipes have excellent performance, meet usage standards, and the recycling process is environmentally friendly and pollution-free, achieving closed-loop utilization. The optimized parameters of the preparation method are adapted to a blended base material with a high proportion of chlorinated polyvinyl chloride, ensuring stable pipe molding quality, complete component structure, and precise dimensions. This meets the needs of cable protection in harsh environments, improving the applicability and reliability of the pipes. In this method for optimizing the performance of environmentally friendly recyclable CPVC cable protection pipe, a double-layer pipe thermo-mechanical coupling stability coefficient is used. The structural and material parameters of the pipe are optimized synergistically, and the coefficients are calculated using the following equations: ; in: Thermo-mechanical coupling stability coefficient (dimensionless), the smaller the value, the more stable the pipe structure is under thermal expansion and impact loads, the target range is... <0.5; The composite elastic modulus (MPa) of CPVC / PVC blend substrates ranges from 2000 to 3000. ΔT: Maximum temperature difference in the working environment (°C), ranging from -30 to 60; The linear expansion coefficient of the material (1 / ℃) ranges from 5 × 10⁻⁶. -5 ~8×10 -5 ; Poisson's ratio (dimensionless) for materials, ranging from 0.35 to 0.40; Material reference stress, taken as the lower limit of the tensile strength of the pipe (MPa), with a value range of ≥50; The wall thickness (mm) of the outer protective tube 1 and the inner buffer tube 2 ranges from 1.5 to 4.0. External impact load (N), ranging from 200 to 1000; Effective contact area (mm) between spiral groove 101 and protruding buckle 201 2 The value range is 50–200; η: Interfacial compatibility coefficient of recycled material (dimensionless), determined experimentally, with a value range of 0.7–1.0. The higher the purity of the recycled material, the closer the η value is to 1.0. The percentage of recycled material by mass (%), ranging from 0 to 100, needs to be normalized to a decimal before being substituted into the equation (e.g., 60% is recorded as 0.6). The extrusion temperature (°C) during recycling and reprocessing ranges from 160 to 190. : Material characteristic temperature, taken as the glass transition temperature (°C) of the CPVC / PVC blend substrate, with a value range of 160–170; k: Temperature decay constant (1 / ℃), reflecting the rate of temperature effect on compatibility, with a value range of 0.03–0.07.

[0018] Equation derivation process: 1. Thermal stress compatibility term: Based on the thermal stress formula for thin-walled cylinders Thin-walled cylinders are defined as having a wall thickness / inner diameter ratio ≤ 0.1. The CPVC cable protection pipes of this invention all meet this applicable condition, and a double-layer wall thickness ratio correction factor is introduced. To reflect the coordinated deformation capability of the inner and outer layers, and divided by the reference stress. Dimensionless transformation is performed to characterize the relative level of thermal stress.

[0019] 2. Impact stability term: The nonlinear deformation of the contact zone under impact load is described by a logarithmic function, where... It represents the relative impact pressure, reflecting the degree of local stress concentration.

[0020] 3. Recycling Compatibility Term: The Sigmoid function is used to simulate the interfacial bonding state of recycled materials at reprocessing temperatures close to... The optimal compatibility is achieved by ensuring the structural stability after recycling. A purity of at least 98% for the recycled material is a prerequisite for this item's value.

[0021] 4. Product form: The product of thermal stress compatibility term and impact stability term reflects the thermo-mechanical coupling effect, and recycling compatibility term is a separate bonus term (because it mainly affects the reprocessing process).

[0022] Example: Take the following parameters: =2800MPa, =8×10 -5 1 / ℃, =0.40; =50 MPa (lower limit of tensile strength); =3.0 mm, =2.5 mm; =60℃, =800N, =200 mm 2 ; η=0.95, =70% (normalized to 0.7), =190℃, =170℃, k=0.07; calculate: 1. Thermal stress compatibility terms: ; 2. Shock stability term: ; 3. Product of thermo-mechanical coupling terms: 0.0692 × 0.07696 ≈ 0.00533; 4. Recycling compatible items: ; 5. =0.00533 + 0.5642 ≈ 0.5695, fine-tuning After reaching 900N, the impact stability term is ln(1+900 / (50×200))≈0.08618, product of thermo-mechanical coupling terms≈0.00607, ≈0.5707, which can be achieved by... Adjusted to 3.8mm, so that The value dropped to 0.489, which is less than 0.5, thus meeting the stability requirements.

[0023] Technical effects: 1. Quantitative thermo-mechanical coupling stability: directly related to the temperature resistance (Vicat softening temperature) and impact strength of the pipe, providing a design basis for performance indicators.

[0024] 2. Guiding structural optimization: By adjusting the wall thickness ratio and contact area It can reduce This improves the reliability of the spiral groove 101 connection. In Example 3, the stability coefficient requirement can be met by finely adjusting the outer wall thickness.

[0025] 3. Collaborative recycling process: The recycling compatibility measures ensure that the recycled and reprocessed pipes still meet the mechanical requirements, supporting the recycling and reprocessing process.

[0026] 4. Prevention of stress cracking: The thermal stress coordination item can predict the stress level under temperature difference, avoid cracking of the slot due to thermal expansion, and extend the service life.

[0027] Working principle and process (in conjunction with preparation method): 1. Input design parameters: including material properties ( ), structural dimensions ( ), environmental conditions ( ) and recycling targets ( All parameters must conform to the value range defined by this invention.

[0028] 2. Calculation Substitute the result into the equation. If the result is ≥0.5, return to step 1 to adjust the parameters (such as increasing the wall thickness or optimizing the slot design).

[0029] 3. Optimize the preparation process: Determine the optimal reprocessing temperature based on the recyclability parameters. And determine the proportion of recycled material. A high proportion of recycled material requires a higher extrusion temperature (180-190℃).

[0030] 4. Output: Obtain stable pipe structure parameters and recycling process parameters to guide twin-screw extrusion, cooling and shaping, and assembly. After the parameters are output, it is necessary to check whether they are consistent with the basic parameters of Examples 1-3.

[0031] 5. Verification: Verify the pipe performance through Vicat softening, impact resistance, and tensile tests, and inspect the recycled pipe materials. To determine whether the requirements are still met, recycled pipes must undergo additional testing to determine the retention rate of flame retardant properties, which must be no less than 85% of that of the original pipes.

[0032] In summary, the overall working principle of this invention is as follows: (I) Structural Working Principle This environmentally friendly, recyclable CPVC cable protection pipe adopts a double-layer structure design with an outer protective pipe 1 and an inner buffer pipe 2, with clear division of labor and synergistic effect. The outer protective pipe 1 mainly undertakes the function of external protection, resisting external mechanical impact, soil corrosion and ultraviolet radiation. The environmentally friendly anti-aging coating on its outer wall has good compatibility with the pipe substrate and can be recycled together, further improving anti-aging performance, slowing down the aging rate of the outer protective pipe 1, and extending the overall service life of the pipe. The inner buffer pipe 2 is in direct contact with the cable. The annular buffer ridge 202 set in the inner wall can reduce the friction between the cable and the inner wall of the inner buffer pipe 2, avoiding damage to the cable insulation layer. At the same time, the annular buffer ridge 202 can absorb external vibration energy, play a buffering and shock-absorbing role, and further protect the cable safety. The outer protective tube 1 and the inner buffer tube 2 are detachably connected via a rotating engagement of a spiral groove 101 and a raised buckle 201. During assembly, the raised buckle 201 engages with the spiral groove 101 and rotates along the groove, achieving a tight connection with an interference fit of 0.1-0.5 mm to prevent loosening during use. Disassembly is achieved by rotating in the opposite direction, facilitating subsequent installation, maintenance, and recycling. In terms of materials, both the outer protective tube 1 and the inner buffer tube 2 use a blend of chlorinated polyvinyl chloride and polyvinyl chloride as the base material, combined with a rare earth composite stabilizer, aluminum-magnesium hydroxide composite flame retardant, and red phosphorus flame retardant. This replaces traditional toxic additives, achieving both material stability and a highly efficient flame-retardant system to prevent flame spread, while also improving the environmental friendliness of the pipes and facilitating recycling. (II) Working principle of preparation and recycling Preparation Principle: During the preparation process, each raw material is weighed according to the predetermined formula. The flame retardant needs to be modified with a silane coupling agent to ensure good compatibility with the blended substrate. Then, all raw materials are added to a high-speed mixer and mixed evenly, followed by plasticizing in a twin-screw plasticizer to obtain a uniform plasticized material. The plasticizing temperature is strictly controlled at 170-180℃ to prevent substrate degradation. Subsequently, through a layered extrusion process, the plasticized material is fed into two extruders to simultaneously form the outer protective tube 1, spiral groove 101, inner buffer tube 2, and protruding buckle 201, ensuring the integrity and dimensional accuracy of each component. After extrusion molding, the inner buffer tube 2 and outer protective tube 1 are rotated and assembled using the spiral groove 101 and protruding buckle 201. The rotation force is controlled at 5-8 N·m to ensure a tight connection. After cooling and shaping, cutting and trimming, an environmentally friendly anti-aging coating is applied, and performance testing is performed. After the coating dries, adhesion is tested, with a grade not lower than level 1. Once qualified, the finished pipe is obtained. Recycling Working Principle: During recycling and reprocessing, the outer protective tube 1, inner buffer tube 2, and matching CPVC sealing ring are first sorted to remove impurities and ensure that the purity of the recycled material is not less than 98%. Then, the sorted pipes are crushed at a low temperature of 40-60℃ to avoid high-temperature degradation, and dried with hot air until the moisture content is less than 0.3% to prevent extrusion molding defects. Subsequently, the recycled granules are blended and modified with new materials in a ratio of 50-70%:30-50%, and then extruded using the established preparation process parameters to obtain recycled pipes. The various properties of the recycled pipes must meet the national / industry standards for cable protection pipes, realizing resource recycling. Moreover, the entire preparation and recycling process has no emissions of toxic or harmful substances, meeting environmental protection requirements. Method of using the present invention (I) Installation Method Before installation, inspect the appearance of the outer protective tube 1 and the inner buffer tube 2 to ensure there is no damage or burrs, the spiral groove 101 and the raised buckle 201 are not deformed or damaged, and the environmentally friendly anti-aging coating is not peeling off and the adhesion level is not lower than level 1. Slowly insert the cable into the inner buffer tube 2, avoiding violent friction between the cable and the inner wall of the inner buffer tube 2 during the insertion process, and use the annular buffer ridge 202 to reduce friction loss. After the cable is inserted, align the raised buckle 201 of the inner buffer tube 2 with the spiral groove 101 of the outer protective tube 1, and rotate the inner buffer tube 2 clockwise until it is rotated into place. After rotation, check the tightness of the connection to ensure there is no looseness or shaking. According to the construction requirements, connect the assembled pipes section by section and place them in the preset construction position. For outdoor construction, the pipe connection points need to be sealed and fixed firmly. (II) Usage and Maintenance Methods During use, the condition of the pipes should be checked every 6-12 months. Observe whether the environmentally friendly anti-aging coating of the outer protective pipe 1 has peeled off, whether the outer protective pipe 1 is damaged or corroded, and whether the connection between the inner buffer pipe 2 and the outer protective pipe 1 is loose. If the outer protective pipe 1 is slightly damaged, repair it with CPVC special glue in time. If the connection is loose, rotate the inner buffer pipe 2 clockwise to further tighten it. Avoid sharp objects hitting the outer protective pipe 1 to prevent the pipe from being damaged and affecting the protective effect. Avoid excessive pulling of the cable to prevent the cable from aggravating the friction between the cable and the inner wall of the inner buffer pipe 2 and damaging the cable insulation layer. If the coating of the pipe used outdoors powders, the environmentally friendly anti-aging coating should be recoated in time. (III) Dismantling and Recycling Methods When disassembly or recycling is required, first remove the components that fix the pipe to avoid damaging the pipe structure during the disassembly process, and slowly pull the cable out of the inner buffer tube 2; then rotate the inner buffer tube 2 counterclockwise to disengage the protruding buckle 201 from the spiral groove 101, thereby separating the outer protective tube 1 from the inner buffer tube 2; collect the separated outer protective tube 1, inner buffer tube 2 and matching CPVC sealing ring separately to avoid mixing in non-CPVC material impurities, remove the surface-adhered mud and impurities, and send them to the designated recycling point; the recycling point sorts, crushes, dries, blends and modifies, and extrudes the collected pipes according to the recycling and reprocessing process of this invention to achieve recycling and avoid resource waste. During the recycling process, it is necessary to ensure that no toxic or harmful substances are emitted and to comply with environmental protection regulations.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. An environmentally friendly, recyclable CPVC cable protection pipe, characterized in that, It includes an outer protective tube (1) and an inner buffer tube (2). The inner wall of the outer protective tube (1) is provided with a spiral groove (101), and the outer wall of the inner buffer tube (2) is provided with a protruding buckle (201) that matches the spiral groove (101). The outer protective tube (1) and the inner buffer tube (2) are detachably connected by the rotational engagement of the spiral groove (101) and the protruding buckle (201). The outer protective tube (1) and the inner buffer tube (2) are both made of a blend of chlorinated polyvinyl chloride and polyvinyl chloride. The blend contains a combination of rare earth composite stabilizer, aluminum magnesium hydroxide composite flame retardant and red phosphorus flame retardant.

2. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, The mass percentage of chlorinated polyvinyl chloride in the blended substrate is 70-85%, and the mass percentage of polyvinyl chloride in the blended substrate is 15-30%; the blended substrate is a mixture of chlorinated polyvinyl chloride and polyvinyl chloride, which is the core substrate of the pipe material.

3. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, Chlorinated polyvinyl chloride (CPVC) and polyvinyl chloride (PVC) are used as the blending base material, and the remaining components are all mass fractions relative to the blending base material. Based on this, the raw material formula includes 70-85% chlorinated polyvinyl chloride, 15-30% polyvinyl chloride, 3-5% rare earth composite stabilizer, 20-25% aluminum magnesium hydroxide composite flame retardant, 5-8% red phosphorus flame retardant, 10-15% modified nano calcium carbonate filler, 5-10% TPU elastomer, and 2-3% low molecular weight CPVC processing aid.

4. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, The depth of the spiral groove (101) is 1.5-2.0mm, the pitch is 4-6mm, the height of the protruding buckle (201) is 1.8-2.5mm, and the interference fit clearance between the protruding buckle (201) and the spiral groove (101) is 0.1-0.5mm.

5. The environmentally friendly recyclable CPVC cable protection pipe according to claim 3, characterized in that, The mass ratio of aluminum hydroxide magnesium composite flame retardant to red phosphorus flame retardant is 3-5:

1. The particle size of the composite flame retardant is 5-15μm, and the surface is modified with silane coupling agent to enhance compatibility with CPVC / PVC blend substrate.

6. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, The recycling and reprocessing process of CPVC cable protection pipes includes the following steps: The first step is recycling and sorting. The recycled outer protective tube (1), inner buffer tube (2) and matching CPVC sealing ring are sorted to remove the soil, impurities and non-CPVC materials attached to the surface, ensuring that the purity of the recycled material is not less than 98%. The second step is crushing. The sorted recycled pipes are crushed into uniform particles with a particle size of 5-10mm. During the crushing process, the crushing temperature is controlled to not exceed 60℃ to avoid degradation of the pipe material due to high temperature. The third step is drying. The crushed recycled particles are placed in a hot air dryer and dried for 2-3 hours at 80-90℃ and 1.2-1.5m / s until the moisture content of the recycled particles is less than 0.3% to prevent defects such as bubbles and shrinkage cavities from occurring in subsequent extrusion molding. The fourth step is blending modification. By mass percentage, 50-70% of the recycled particles and 30-50% of the new material are put into a high-speed mixer and mixed at 100-110℃ for 15-20 minutes to ensure that the recycled particles and the new material are evenly dispersed. The fifth step is extrusion molding, using the preparation process described in claim 10. The temperature of the extruder feed section is controlled at 160-170℃, the melting section at 175-185℃, and the die head at 180-190℃, and the screw speed is 25-35 r / min. After extrusion molding, the material is cooled, shaped, and cut to obtain recycled pipe. The recycled pipe has an impact strength of not less than 12MPa, a tensile strength of not less than 45MPa, and a Vicat softening temperature of not less than 90℃. All properties meet the standards for cable protection pipes, and the recycling and reprocessing process does not emit any toxic or harmful substances, achieving environmentally friendly closed-loop utilization.

7. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, CPVC cable protection pipes have a Vicat softening temperature of not less than 93℃, an impact strength of not less than 15MPa, a tensile strength of not less than 50MPa, a service life of not less than 50 years, a quality recovery rate of not less than 90%, and a purity of recycled materials of not less than 98%.

8. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, The inner wall of the inner buffer tube (2) is uniformly provided with annular buffer ridges (202). The height of the annular buffer ridges (202) is 0.8-1.2mm, the width is 1.0-1.5mm, and the spacing between adjacent annular buffer ridges (202) is 3-5mm. The annular buffer ridges (202) and the inner buffer tube (2) are integrally extruded and molded to reduce the friction between the cable and the inner wall of the inner buffer tube (2), while enhancing the buffering and shock absorption performance and protecting the cable insulation layer.

9. The environmentally friendly recyclable CPVC cable protection pipe according to claim 1, characterized in that, The outer wall of the outer protective tube (1) is uniformly coated with an environmentally friendly anti-aging coating with a thickness of 0.3-0.5mm. The environmentally friendly anti-aging coating is a composite coating of polysiloxane and nano titanium dioxide, in which the mass ratio of nano titanium dioxide is 8-12%. It is used to improve the UV resistance and anti-aging performance of the outer protective tube (1), slow down the aging speed of the pipe, and further extend the service life of the pipe. The anti-aging coating can be recycled and reprocessed together with the pipe. The coating has good compatibility with CPVC / PVC blended substrate and does not affect the mechanical and flame retardant properties of the recycled material.

10. A method for preparing an environmentally friendly recyclable CPVC cable protection pipe according to any one of claims 1-9, characterized in that, Includes the following steps: The first step is raw material preparation. Weigh each raw material according to the mass ratio and relative mass fraction of the blended substrate as described in claim 3. The aluminum magnesium hydroxide composite flame retardant and the red phosphorus flame retardant are mixed in the proportion described in claim 5 and modified by silane coupling agent. The second step is mixing and plasticizing. Chlorinated polyvinyl chloride, polyvinyl chloride, rare earth composite stabilizer, modified composite flame retardant, modified nano calcium carbonate filler, TPU elastomer and low molecular weight CPVC processing aid are put into a high-speed mixer and mixed at 105-115℃ for 20-25 minutes until uniform. Then it is fed into a twin-screw plasticizer and plasticized at 170-180℃ for 8-12 minutes to obtain a uniform plasticized material. The third step is layered extrusion. The plasticized material is fed into two extruders. One extruder extrudes the outer protective tube (1), and a spiral groove (101) is formed simultaneously during the extrusion process. The extrusion temperature is controlled at 165-175℃ and the screw speed is 30-40r / min. The other extruder extrudes the inner buffer tube (2), and a protruding buckle (201) is formed simultaneously during the extrusion process. The extrusion temperature is controlled at 160-170℃ and the screw speed is 35-45r / min. The fourth step is to assemble and form the inner buffer tube (2) and the outer protective tube (1) after extrusion. The inner buffer tube (2) and the outer protective tube (1) are rotated and engaged by the spiral groove (101) and the protruding buckle (201) to achieve detachable assembly. During the assembly process, the rotation force is controlled to be 5-8 N·m to ensure that the connection is tight and there is no looseness. The fifth step is subsequent processing. The assembled pipe is cooled and shaped at a temperature of 20-30℃ for 15-20 minutes. After shaping, the two ends of the pipe are cut and trimmed to remove burrs. Then, an environmentally friendly anti-aging coating is applied to the outer wall of the outer protective pipe (1). After the coating dries, an adhesion test is conducted. The adhesion level is not lower than level 1. After the coating dries, the performance is tested. Once qualified, it can be packaged and stored.

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