Crosslinked polyethylene composite rat-and-termite-resistant cable sheath and preparation method thereof

Abstract

The invention relates to the field of cable materials, in particular to a crosslinked polyethylene composite rat-and-termite-resistant cable sheath and a preparation method thereof. The cross-linked polyethylene composite rat-and-ant-resistant cable sheath is prepared from the following raw materials in parts by mass: 100 to 120 parts of low-density polyethylene, 2 to 4 parts of cross-linking agent, 0.6 to 1.2 parts of combined antioxidant, 6 to 10 parts of rat-and-ant-resistant agent, 5 to 10 parts of interface coordination composition, 3 to 5 parts of lubricating agent, 0.5 to 1.5 parts of dispersing agent, 20 to 25 parts of filler and 4 to 10 parts of reinforcing agent. According to the cross-linked polyethylene composite rat-and-ant-resistant cable sheath provided by the invention, the comprehensive improvement of the rat-and-ant-resistant performance, the mechanical strength and the processing adaptability is realized on the premise that metal armoring and high-filling inorganic powder are not needed through the cooperation of all the components.

Description

Technical Field

[0001] This invention relates to the field of cable materials, and in particular to a cross-linked polyethylene composite rodent- and ant-resistant cable sheath and its preparation method. Background Technology

[0002] In the fields of power transmission and communication, cables, as critical infrastructure, require outer sheath materials that not only possess excellent mechanical strength, weather resistance, and electrical insulation properties, but also effectively resist damage from external biological factors, especially rodents and termites. In southern my country and tropical and subtropical regions, termite activity is frequent, while rodent infestations are also prominent in urban-rural fringe areas, farmland, and forest areas. These creatures often gnaw on cable sheaths to wear down their teeth or build nests, damaging the cable insulation layer and potentially leading to serious safety accidents such as short circuits, leakage, and even fires. Therefore, developing cable sheath materials with excellent rodent and termite resistance has become an important technical direction for ensuring the safe and stable operation of the power grid.

[0003] Currently, conventional cable sheaths are mostly made of polymer materials such as polyvinyl chloride (PVC), polyethylene (PE), or cross-linked polyethylene (XLPE). Among them, cross-linked polyethylene is widely used in the insulation layer and some sheath structures of medium and high voltage power cables due to its excellent thermal stability, electrical properties, and chemical corrosion resistance. However, pure XLPE material itself has no resistance to biological erosion, and its protective effect against rodent and ant infestations is limited. To improve rodent and ant resistance, existing technologies usually involve adding repellents or physical reinforcement methods to the sheath material.

[0004] While the aforementioned methods improve the rodent and termite resistance of cables to some extent, performance issues remain. For example, additive repellents are prone to migration, volatilization, or washout by rainwater over time, resulting in inconsistent protective effects, especially in high-temperature and high-humidity environments. Secondly, while adding large amounts of inorganic fillers can increase hardness, it often sacrifices the material's flexibility and processing performance, making extrusion molding difficult and easily causing stress concentration, thus reducing the overall mechanical reliability of the cable. Furthermore, although metal armor provides reliable physical protection, it significantly increases the cable's weight and cost, making it unsuitable for long-distance laying, and it may still fail due to localized damage in non-metallic pipes or direct burial environments. Finally, existing double-layer sheath structures often lack systematic optimization of the interfacial compatibility and synergistic effects between the two layers, resulting in insufficient interlayer adhesion. Under bending, tensile, or thermal cycling conditions, delamination and cracking can easily occur, providing pathways for rodent and termite intrusion.

[0005] Therefore, there is an urgent need to develop a new type of cable sheath that combines long-lasting rodent and ant protection, good mechanical properties, and processability to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] In order to solve the aforementioned problems related to the prior art, this invention application provides the following technical solution: The first aspect of this invention provides a cross-linked polyethylene composite rodent- and termite-resistant cable sheath, comprising, by weight, the following raw materials: 100-120 parts of low-density polyethylene, 2-4 parts of cross-linking agent, 0.6-1.2 parts of combined antioxidant, 6-10 parts of rodent- and termite repellent, 5-10 parts of interface compatibility composition, 3-5 parts of lubricant, 0.5-1.5 parts of dispersant, 20-25 parts of filler, and 4-10 parts of reinforcing agent.

[0007] In a preferred embodiment, the low-density polyethylene has a melt flow rate of 4~5 g / 10 min and a melt flow rate of 190℃ / 2.16 kg.

[0008] A more preferred embodiment is that the low-density polyethylene has a melt flow rate of 4~4.2 g / 10 min and a melt flow rate of 190℃ / 2.16 kg.

[0009] A more preferred embodiment is that the low-density polyethylene is specifically LDPE 5004I, manufactured by Dow Chemical Company, USA.

[0010] In a preferred embodiment, the mass ratio of the low-density polyethylene, the interface-coordinating composition, and the reinforcing agent is (10~11.5):(0.6~1):(0.5~0.9).

[0011] In a more preferred embodiment, the mass ratio of the low-density polyethylene, the interface-coordinating composition, and the reinforcing agent is (10~11):(0.7~0.8):(0.6~0.7).

[0012] In a preferred embodiment, the crosslinking agent is at least one of dicumyl peroxide, di-tert-butyl peroxide, and benzoyl peroxide.

[0013] In a more preferred embodiment, the crosslinking agent is dicumyl peroxide or benzoyl peroxide.

[0014] In a more preferred embodiment, the crosslinking agent is dicumyl peroxide.

[0015] In a preferred embodiment, the combined antioxidant is a combination of antioxidant 1010 and antioxidant 168.

[0016] In a preferred embodiment, the mass ratio of antioxidant 1010 to antioxidant 168 is (1~2):(1~2).

[0017] In a more preferred embodiment, the mass ratio of antioxidant 1010 to antioxidant 168 is (1~1.2):1.

[0018] In a preferred embodiment, the rodent repellent is a combination of microencapsulated capsaicin, benzyl dinatamide, and neem oil.

[0019] In a preferred embodiment, the mass ratio of the microencapsulated capsaicin, benzodiazepine, and neem oil is (4~6):(0.5~1):(1~2).

[0020] A more preferred embodiment is that the mass ratio of the microencapsulated capsaicin, benzodiazepine, and neem oil is (4.5~5):(0.6~0.8):(1.3~1.6).

[0021] In a preferred embodiment, the interface-coordinating composition is a combination of ethylene-acrylic acid copolymer and ethylene-butyl acrylate copolymer.

[0022] In a preferred embodiment, the mass ratio of the ethylene-acrylic acid copolymer to the ethylene-butyl acrylate copolymer is (3~5):(2~3).

[0023] In a more preferred embodiment, the mass ratio of the ethylene-acrylic acid copolymer to the ethylene-butyl acrylate copolymer is (4~5):(2.4~2.8).

[0024] A more preferred embodiment is that the ethylene-acrylic acid copolymer is Primacor 1410, manufactured by Dow Chemical Company, USA.

[0025] A more preferred embodiment is that the ethylene-butyl acrylate copolymer is specifically Elvaloy AC 3427, manufactured by Dow Chemical Company, USA.

[0026] The interface-coordinating composition added in this invention provides a solid foundation for the excellent comprehensive performance of the cable sheath. The carboxyl groups contained therein can form hydrogen bonds with the polar groups of microcapsule capsaicin and denatum, effectively fixing the repellent molecules in the polyethylene matrix and significantly inhibiting their migration and loss. Furthermore, with its compliant long-chain structure, it forms an elastic interface layer in the matrix, absorbing impact energy and compensating for the toughness loss caused by microcapsule particles. The combined effect of these two factors allows the sheath to maintain a high repellent retention rate while still possessing excellent elongation at break and low-temperature toughness. This solves the technical contradiction of traditional repellent systems being prone to failure and sheaths becoming brittle from the two levels of micro-interface compatibility and macro-mechanical enhancement.

[0027] In a preferred embodiment, the lubricant is at least one selected from naphthenic oil, liquid paraffin, white oil, and polybutene.

[0028] A more preferred embodiment is that the lubricant is a combination of naphthenic oil and liquid paraffin.

[0029] In a preferred embodiment, the mass ratio of the naphthenic oil to the liquid paraffin is (2~3):(1~1.5).

[0030] In a more preferred embodiment, the mass ratio of the naphthenic oil to the liquid paraffin is (2~2.5):(1~1.2).

[0031] In a preferred embodiment, the dispersant is at least one of zinc stearate, calcium stearate, magnesium stearate, polyethylene wax, and ethylene bis-stearamide.

[0032] In a more preferred embodiment, the dispersant is zinc stearate or ethylene bis-stearamide.

[0033] In a more preferred embodiment, the dispersant is zinc stearate.

[0034] In a preferred embodiment, the filler is at least one selected from carbon black, calcium carbonate, talc, mica powder, and wollastonite powder.

[0035] In a more preferred embodiment, the filler is carbon black.

[0036] In a preferred embodiment, the average particle size of the carbon black is 25~100nm.

[0037] In a more preferred embodiment, the average particle size of the carbon black is 25~50 nm.

[0038] In a preferred embodiment, the reinforcing agent is a combination of hydroxyl-terminated polybutadiene and glyceryl monostearate.

[0039] In a preferred embodiment, the mass ratio of the hydroxyl-terminated polybutadiene to glyceryl monostearate is (4~6):(1~2).

[0040] In a more preferred embodiment, the mass ratio of the hydroxyl-terminated polybutadiene to glyceryl monostearate is (4.8~5.4):(1.5~1.8).

[0041] In a preferred embodiment, the number-average molecular weight of the hydroxyl-terminated polybutadiene is 2000~5000 Da.

[0042] In a more preferred embodiment, the number-average molecular weight of the hydroxyl-terminated polybutadiene is 4000~4500 Da.

[0043] This invention utilizes a compound of hydroxyl-terminated polybutadiene and glyceryl monostearate to form continuous flexible microdomains within a polyethylene matrix. These microdomains significantly absorb impact energy and encapsulate repellent microcapsules with their hydrophobic properties, preventing core material loss due to moisture erosion. Furthermore, by leveraging polar hydroxyl groups, a nanoscale polar reservoir is constructed within the non-polar matrix. By controlling the slow release of denatum benzoate to the surface through polarity differences, the bittering agent is intelligently controlled and released. This combined effect ensures that the cross-linked polyethylene sheath maintains excellent toughness and processing stability while providing a long-lasting and stable repellent effect. This invention addresses the problems of easy failure and insufficient flexibility of traditional sheath repellents from both physical protection and release regulation perspectives.

[0044] The second aspect of this invention provides a method for preparing the above-mentioned cross-linked polyethylene composite rodent- and termite-resistant cable sheath, specifically including the following steps: S1: Low-density polyethylene, an interface-coordinating composition, a combination of antioxidants, and a lubricant are added to a Banbury mixer and mixed at 120-125°C and a rotor speed of 50-60 rpm for 4-5 minutes until the torque stabilizes at 12-15 N·m. Then, the temperature is lowered to 105-110°C, the rotor speed is reduced to 30-40 rpm, a rodent- and termite-resistant agent is added, and the mixture is mixed for 3-4 minutes. Next, fillers, dispersants, and reinforcing agents are added and mixed for another 3-4 minutes. Then, the temperature is adjusted to 115-125°C, the rotor speed is 25-30 rpm, a cross-linking agent is added, and the mixture is mixed for 3-5 minutes, controlling the system temperature to be less than or equal to 125°C. After completion, the material is quickly discharged to an open mixing mill with a roll gap of 1-1.2 mm. S1: Roller temperature 40~45℃, thin film passed through twice and cooled to room temperature; S2: Single screw extrusion granulation, feeding section 120℃, compression section 130℃, homogenization section 140℃, die head 145℃, die opening 140℃, screw speed 80~100rpm, after dehydration the granules enter the vibrating fluidized bed dryer, dry at 40~45℃ for 5~8min, vibrating screen removes long strips and powder to obtain qualified granules; S3: The granules are extruded through a cable extruder at feeding section 120℃, compression section 150℃, homogenization section 170℃, die head 175℃, die opening 180℃, screw speed 35~50rpm, extrusion line speed 2.5~3m / min, crosslinking tube temperature 200℃, after extrusion enters the cooling water tank, then is wound up and left to stand at room temperature for 24~30h to obtain the finished product.

[0045] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath provided in this invention application, through the synergistic effect of its components, achieves a comprehensive improvement in rodent and ant resistance, mechanical strength, and processing adaptability without the need for metal armor or highly filled inorganic powder. The sheath provides a durable and stable repellency against rodent and ant bites, effectively preventing insulation damage and electrical safety accidents caused by biological erosion. Simultaneously, the material possesses excellent flexibility, heat aging resistance, and environmental stress cracking resistance, adapting to complex laying environments and long-term operational requirements. Furthermore, the overall solution exhibits good process compatibility, smooth extrusion molding, and controllable production costs, significantly improving the overall service life and operational reliability of the cable sheath.

[0046] 2. The interface coordination composition added in this invention provides a solid foundation for the excellent comprehensive performance of the cable sheath. The carboxyl groups contained therein can form hydrogen bonds with the polar groups of microcapsule capsaicin and denatum, effectively fixing the repellent molecules in the polyethylene matrix and significantly inhibiting their migration and loss. Furthermore, with its compliant long-chain structure, it forms an elastic interface layer in the matrix, absorbing impact energy and compensating for the toughness loss caused by microcapsule particles. The combined effect of these two factors allows the sheath to maintain a high repellent retention rate while still possessing excellent elongation at break and low-temperature toughness.

[0047] 3. This invention application incorporates hydroxyl-terminated polybutadiene and glyceryl monostearate to form continuous flexible microdomains within a polyethylene matrix. These microdomains significantly absorb impact energy and encapsulate repellent microcapsules with their hydrophobic properties, preventing core material loss due to moisture erosion. Furthermore, by utilizing polar hydroxyl groups to construct nanoscale polar reservoirs within a non-polar matrix, the slow release of denatamine benzoate to the surface is controlled through polarity differences, achieving intelligent controlled release of the bittering agent. The combined effect ensures that the cross-linked polyethylene sheath maintains excellent toughness and processing stability while providing a long-lasting and stable repellent effect. Attached Figure Description

[0048] Figure 1 This is a physical image of the cross-linked polyethylene composite rodent- and ant-resistant cable sheath prepared according to Example 1 of this application. Detailed Implementation

[0049] The technical solutions in the embodiments of this invention will be clearly and completely described below. The described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] In the following specific embodiments, unless otherwise specified, the sources / preparation methods of some raw materials are as follows: Low-density polyethylene LDPE 5004I, Dow Chemical, USA.

[0051] Microencapsulated capsaicin LLS-312, produced by Leitai Biotechnology, Tonglu, China.

[0052] Neem oil, from Wuhan, China.

[0053] Primacor 1410, an ethylene-acrylic acid copolymer, is produced by Dow Chemical Company, USA.

[0054] Ethylene-butyl acrylate copolymer Elvaloy AC 3427, Dow Chemical Co., Ltd.

[0055] Naphthenic oil 4010, Hebei Wantai Chemical Co., Ltd., China.

[0056] Hydroxyl-terminated polybutadiene, number average molecular weight 4100 Da, Wuhan Jiyesheng Chemical Co., Ltd., China. Example

[0057] A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 100 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 7.2 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 6.6 parts reinforcing agent.

[0058] The low-density polyethylene is specifically LDPE 5004I; the crosslinking agent is dicumyl peroxide.

[0059] The combined antioxidant is a combination of antioxidant 1010 and antioxidant 168 in a mass ratio of 1.2:1.

[0060] The rodent and ant repellent is a combination of microencapsulated capsaicin LLS-312, benzodiazepine, and neem oil in a mass ratio of 4.7:0.8:1.5.

[0061] The interface-coordinating composition is a combination of ethylene-acrylic acid copolymer Primacor 1410 and ethylene-butyl acrylate copolymer Elvaloy AC 3427 in a mass ratio of 4.5:2.5.

[0062] The lubricant is a combination of naphthenic oil 4010 and liquid paraffin in a mass ratio of 2.3:1.2.

[0063] The dispersant is zinc stearate; the filler is carbon black with an average particle size of 30 nm.

[0064] The reinforcing agent is a combination of hydroxyl-terminated polybutadiene and glyceryl monostearate in a mass ratio of 5:1.5.

[0065] A method for preparing the above-mentioned cross-linked polyethylene composite rodent- and termite-resistant cable sheath specifically includes the following steps: S1: Low-density polyethylene, interface-coordinating composition, combined antioxidant, and lubricant are added to a mixer and mixed at 120°C and a rotor speed of 50 rpm for 4 minutes until the torque stabilizes at 14 N·m. Then, the temperature is lowered to 110°C, the rotor speed is reduced to 40 rpm, rodent- and termite-resistant agent is added, and the mixture is mixed for 4 minutes. Then, filler, dispersant, and reinforcing agent are added and mixed for 4 minutes. After that, the temperature is adjusted to 125°C, the rotor speed is 25 rpm, cross-linking agent is added, and the mixture is mixed for 4 minutes. The system temperature is controlled to be less than or equal to 125°C. After completion, the material is quickly discharged into an open mixing mill with a roll gap of 1 mm. S1: 40℃, thin film is passed through two passes and cooled to room temperature; S2: Single screw extrusion granulation, feeding section 120℃, compression section 130℃, homogenization section 140℃, die head 145℃, die opening 140℃, screw speed 80rpm, after dehydration the granules enter the vibrating fluidized bed dryer, dry at 45℃ for 6min, and remove long strips and powder with a vibrating screen to obtain qualified granules; S3: The granules are extruded through a cable extruder at feeding section 120℃, compression section 150℃, homogenization section 170℃, die head 175℃, die opening 180℃, screw speed 40rpm, extrusion line speed 2.5m / min, crosslinking tube temperature 200℃, after extrusion enters the cooling water tank, and then is wound up and left to stand at room temperature for 24h to complete the process.

[0066] The actual product of the cross-linked polyethylene composite rodent- and ant-resistant cable sheath obtained in this embodiment is shown below. Figure 1 As shown. Example

[0067] A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 110 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 6.5 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 7.5 parts reinforcing agent. Example

[0068] A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 110 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 8.8 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 5.9 parts reinforcing agent.

[0069] Comparative Example 1 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 120 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 3.5 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 8.5 parts reinforcing agent.

[0070] The remaining implementation methods are the same as in Example 1.

[0071] Comparative Example 2 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 115 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 9.5 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 2.3 parts reinforcing agent.

[0072] The remaining implementation methods are the same as in Example 1.

[0073] Comparative Example 3 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 100 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 7.2 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 6.6 parts reinforcing agent.

[0074] The interface-coordinating composition is a combination of ethylene-acrylic acid copolymer Primacor 1410 and ethylene-butyl acrylate copolymer Elvaloy AC 3427 in a mass ratio of 6:1.

[0075] The remaining implementation methods are the same as in Example 1.

[0076] Comparative Example 4 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 100 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 7.2 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 6.6 parts reinforcing agent.

[0077] The interface-coordinating composition is a combination of ethylene-acrylic acid copolymer Primacor 1410 and ethylene-butyl acrylate copolymer Elvaloy AC 3427 in a mass ratio of 3:4.

[0078] The remaining implementation methods are the same as in Example 1.

[0079] Comparative Example 5 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 100 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 7.2 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 6.6 parts reinforcing agent.

[0080] The reinforcing agent is a combination of hydroxyl-terminated polybutadiene and glyceryl monostearate, with a mass ratio of 6.2:0.3.

[0081] The remaining implementation methods are the same as in Example 1.

[0082] Comparative Example 6 A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, by weight, comprises the following raw materials: 100 parts low-density polyethylene, 2.8 parts cross-linking agent, 0.7 parts combined antioxidant, 8.5 parts rodent- and ant repellent, 7.2 parts interface compatibility composition, 3.4 parts lubricant, 0.8 parts dispersant, 22 parts filler, and 6.6 parts reinforcing agent.

[0083] The reinforcing agent is a combination of hydroxyl-terminated polybutadiene and glyceryl monostearate in a mass ratio of 3:3.5.

[0084] The remaining implementation methods are the same as in Example 1.

[0085] Performance testing 1. Mechanical properties: 5A dumbbell-shaped test pieces were cut from the cross-linked polyethylene composite rodent-resistant cable sheath along the extrusion direction. The thickness was 2.0±0.2 mm, the width of the narrow parallel section was 4 mm, and the gauge length was 25 mm. The test pieces were conditioned at a temperature of 23±2℃ and a relative humidity of 50±5% for 48 h. Tensile tests were performed using an electronic universal testing machine at a stretching rate of 200 mm / min. The average tensile strength and elongation at break of 10 tests were recorded in Table 1.

[0086] 2. Rodent resistance: Cut 6 test pieces (100mm×50mm×2.0mm) from the protective cover and weigh them accurately to 0.1mg. The test animals were SD rats, weighing 200-250g, housed in individual cages and fasted for 24 hours. The test pieces were fixed in the cages and exposed for 14 consecutive days with free access to water and a fixed amount of food per day. After cleaning and drying, the test pieces were weighed again and the mass loss rate was calculated. The results of the 6 test groups were averaged and recorded in Table 1.

[0087] 3. Durability: Dumbbell-shaped specimens were prepared according to the same requirements as the tensile test. Five specimens were prepared for each group before aging and five specimens after aging. The specimens before aging were placed in a forced-ventilation oven at 135±2℃ for 168 hours. After aging, the specimens were taken out and conditioned at 23±2℃ for 24 hours. The tensile properties were tested simultaneously with the specimens before aging. The retention rate of tensile strength after aging was calculated, and the average value of the results was recorded in Table 1.

[0088] 4. Retention rate of repellent accelerated aging: Powder sample was cut from the sheath, 1.0 g was accurately weighed and placed in an aluminum dish, and placed in a constant temperature and humidity chamber at 85±2℃ and 85±5% relative humidity for 30 consecutive days. The sample was then removed and the residual content of capsaicin in the sheath after aging was determined by gas chromatography-mass spectrometry. The retention rate was calculated by comparing it with the initial content before aging, and the results were recorded in Table 1.

[0089] 5. Resistance to termite infestation: Cut 50mm×50mm×2mm square test pieces from the protective sleeve, 50 pieces per group. The termites used in the test are Formosan subterranean termites. Each container contains 300 worker termites and 30 soldier termites. Place the test pieces at the bottom of the container and expose them for 30 days at a temperature of 28±1℃ and a relative humidity of 85±5%. After removing the test pieces, clean and dry them, and observe the surface infestation using a volumetric microscope. If there are obvious infestation marks, perforations, or any deep infestation on the surface, it is considered unqualified. Otherwise, if there are no such phenomena, it is considered qualified. Record the pass rate results of 50 groups of tests in Table 1.

[0090] Table 1 Performance Test Results

[0091] Test Result Analysis: Examples 1-3, by employing the relevant technical solutions defined in this invention application, can effectively fix the repellent molecules in the polyethylene matrix, significantly inhibiting their migration and loss. Furthermore, by utilizing the compliant long-chain structure to form an elastic interface layer in the matrix, it absorbs impact energy and compensates for the toughness loss caused by microcapsule particles. In addition, it forms continuous flexible micro-regions in the polyethylene matrix, significantly absorbing impact energy and encapsulating the repellent microcapsules with its hydrophobic properties, preventing the loss of core material caused by moisture erosion. Furthermore, by utilizing polar hydroxyl groups to construct a nanoscale polar reservoir in the non-polar matrix, the slow release of benzophenone to the surface is controlled by polarity differences, achieving intelligent controlled release of the bittering agent. Under the combined effect, the cross-linked polyethylene sheath maintains excellent toughness and processing stability while ensuring a long-lasting and stable repellent effect. Therefore, it achieves better performance results compared to Comparative Examples 1-6 (which employ corresponding technical solutions not defined in this invention application).

[0092] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cross-linked polyethylene composite rodent- and ant-resistant cable sheath, characterized in that: By weight, the raw materials include: 100-120 parts of low-density polyethylene, 2-4 parts of crosslinking agent, 0.6-1.2 parts of combined antioxidant, 6-10 parts of rodent repellent, 5-10 parts of interface compatibility composition, 3-5 parts of lubricant, 0.5-1.5 parts of dispersant, 20-25 parts of filler, and 4-10 parts of reinforcing agent; The low-density polyethylene has a melt flow rate of 4~5 g / 10 min and a melt flow rate of 190℃ / 2.16 kg. The rodent repellent is a combination of microencapsulated capsaicin, benzyl dinatamide, and neem oil, in a mass ratio of (4~6):(0.5~1):(1~2). The interface-coordinating composition is a combination of ethylene-acrylic acid copolymer and ethylene-butyl acrylate copolymer in a mass ratio of (3~5):(2~3).

2. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 1, characterized in that: The crosslinking agent is at least one of dicumyl peroxide, di-tert-butyl peroxide, and benzoyl peroxide.

3. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 2, characterized in that: The mass ratio of the low-density polyethylene, the interface-coordinating composition, and the reinforcing agent is (10~11.5):(0.6~1):(0.5~0.9).

4. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 3, characterized in that: The crosslinking agent is at least one of dicumyl peroxide, di-tert-butyl peroxide, and benzoyl peroxide.

5. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 4, characterized in that: The combined antioxidant is a combination of antioxidant 1010 and antioxidant 168, with a mass ratio of (1~2):(1~2).

6. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 5, characterized in that: The lubricant is at least one of naphthenic oil, liquid paraffin, white oil, and polybutene.

7. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 6, characterized in that: The dispersant is at least one of zinc stearate, calcium stearate, magnesium stearate, polyethylene wax, and ethylene bis-stearamide.

8. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 7, characterized in that: The reinforcing agent is a combination of hydroxyl-terminated polybutadiene and glyceryl monostearate, with a mass ratio of (4~6):(1~2).

9. The cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to claim 8, characterized in that: The number-average molecular weight of the hydroxyl-terminated polybutadiene is 2000~5000 Da.

10. A method for preparing the cross-linked polyethylene composite rodent- and ant-resistant cable sheath according to any one of claims 1 to 9, characterized in that: Specifically, the following steps are included: S1: Add low-density polyethylene, interface-coordinating composition, combined antioxidants, and lubricant to a Banbury mixer. Mix at 120-125°C and a rotor speed of 50-60 rpm for 4-5 minutes until the torque stabilizes at 12-15 N·m. Then cool to 105-110°C, reduce the rotor speed to 30-40 rpm, add rodent repellent, and mix for 3-4 minutes. Next, add filler, dispersant, and reinforcing agent, and mix for another 3-4 minutes. Then adjust the temperature to 115-125°C and the rotor speed to 25-30 rpm, add crosslinking agent, and mix for 3-5 minutes, controlling the system temperature to be less than or equal to 125°C. After completion, quickly discharge the material to an open mixing mill with a roll gap of 1-1.2 mm. S1: Roller temperature 40~45℃, thin sheeting twice and cooled to room temperature; S2: Single screw extrusion granulation, feeding section 120℃, compression section 130℃, homogenization section 140℃, die head 145℃, die opening 140℃, screw speed 80~100rpm, after dehydration the granules enter the vibrating fluidized bed dryer, dry at 40~45℃ for 5~8min, and remove long strips and powder with a vibrating screen to obtain qualified granules; S3: The granules are extruded through a cable extruder at a feeding section of 120°C, a compression section of 150°C, a homogenization section of 170°C, a die head of 175°C, and a die opening of 180°C. The screw speed is 35~50 rpm, the extrusion line speed is 2.5~3 m / min, and the crosslinking tube temperature is 200°C. After extrusion, the material enters a cooling water tank, and then is wound up and left to stand at room temperature for 24~30 hours to complete the process.

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