Preparation process of bio-barrier rat-proof and termite-proof aluminum alloy core cable

Abstract

The application discloses a kind of biological barrier rat-proof and termite-proof aluminum alloy core cable preparation process.The process includes: S1 preparation of insect-resistant composite material, modified natural plant fiber, polylactic acid resin and bio-based plasticizer are melt mixed, reactive mixing is added to covalent anchoring type organosilicon quaternary ammonium salt insecticide, and natural repellent ingredients are added;S2 preparation of functional outer sheath material, polyvinyl chloride resin is mixed at high speed with biological protection additive, functional pigment and the like;S3 cable structure is constructed, aluminum alloy is used as core material, the outer surface of conductive core material is coated with polytetrafluoroethylene micro powder coating, crosslinked polyethylene insulation layer, shielding layer are sequentially coated, insect-resistant composite material is extruded to form inner protective layer, and finally functional outer sheath material is extruded to form outer protective layer.Covalent anchoring type insecticide is chemically bonded to substrate through amino end group to achieve durable fixation, and natural repellent ingredients are compounded to achieve broad-spectrum repellent.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically relating to a manufacturing process for a bio-barrier rodent-proof and ant-proof aluminum alloy core cable. Background Technology

[0002] As power transmission networks continue to extend into remote areas, humid coastal environments, and underground installations, cables face increasingly severe biological damage problems. The gnawing and erosion of cable sheaths by rodents such as rats and voles, as well as insects like ants and termites, not only causes insulation failure and decreased conductivity but can also lead to short circuits, fires, and other safety accidents, seriously threatening the stable operation of the power system.

[0003] Traditional cable protection against biological attack mainly relies on physical barriers, such as covering the cable with a metal armor layer or a rigid polymer sheath. However, metal armor significantly increases cable weight and cost, and is prone to corrosion in humid environments; while rigid polymer sheaths offer some protection against biting, their poor flexibility makes them susceptible to cracking and failure under frequent bending or thermal expansion and contraction.

[0004] Chemical repellents are another common approach, involving the addition of chemical repellents to the sheath material to prevent biological approach. However, most existing chemical repellents are organic solvents, which suffer from high volatility, short duration of effectiveness, and environmental pollution. More importantly, these repellents are loosely bonded to the polymer matrix, making them prone to leaching and loss during long-term use, leading to a sharp decline in protective effectiveness.

[0005] Furthermore, most existing technologies employ a single protection mechanism, relying either purely on physical barriers or solely on chemical repellency, lacking a synergistic design for multiple layers of protection. For aluminum alloy core cables, the differences in mechanical strength and corrosion resistance between aluminum alloy and copper place higher demands on the protective performance of the outer sheath system.

[0006] With increasingly stringent environmental regulations, traditional protective technologies also face problems such as poor biodegradability and insufficient environmental friendliness. Most existing cable sheath materials are pure synthetic polymers, which are difficult to degrade naturally after their service life, causing a persistent environmental burden.

[0007] In summary, existing cable bioprotection technologies generally suffer from the following shortcomings: First, the protection mechanism is singular and lacks multiple synergistic protections; second, chemical repellents are easily lost, resulting in unstable long-term protective effects; third, it is difficult to balance mechanical and protective performance; fourth, they are not environmentally friendly and have poor biodegradability; and fifth, there is a lack of specialized protection technologies for aluminum alloy core cables. Summary of the Invention

[0008] This invention aims to provide a bio-barrier rodent-proof and ant-proof aluminum alloy core cable and its manufacturing process. By constructing a dual-layer synergistic system of an insect-resistant composite bio-barrier protective layer and a functional outer sheath layer, it achieves long-term repellency and physical barrier against rodents and ants. At the same time, it takes into account mechanical wear resistance, weather resistance and insulation safety, and is suitable for long-term stable operation in humid, outdoor and biological attack risk scenarios.

[0009] To achieve the above objectives, this invention provides a manufacturing process for a bio-barrier rodent- and termite-proof aluminum alloy core cable, which is implemented according to the following steps: Preparation of S1 insect-resistant composite material: Modified natural plant fiber and polylactic acid resin are added to a twin-screw extruder and heated. Bio-based plasticizer is added and stirred. Then, covalently anchored organosilicon quaternary ammonium salt insect repellent is added. After the mixing reaction is completed, natural repellent components, interface compatibilizers and processing aids are added and mixed evenly to obtain the insect-resistant composite material.

[0010] Preparation of S2 functional outer sheath material: Weigh out polyvinyl chloride resin and heat it. Then add biological protective additives, shielding functional pigments, wear-resistant modifiers and heat stabilizers in sequence. Mix them in a high-speed mixer to obtain a functional outer sheath material.

[0011] Construction of S3 cable structure: Using aluminum alloy as the conductive core material, the outer surface of the conductive core material is coated with polytetrafluoroethylene (PTFE) micro powder coating, the PTFE micro powder coating is covered with a cross-linked polyethylene (XLPE) insulation layer, and the XLPE insulation layer is covered with a metal shielding layer. Then, the insect-resistant composite material prepared in step S1 and the functional outer sheath material prepared in step S2 are extruded simultaneously to form an inner biological barrier protective layer and an outer functional sheath layer, respectively. After cooling and shaping, a biological barrier rodent-proof and ant-proof aluminum alloy core cable is obtained.

[0012] Further, step S1, preparing the insect-resistant composite material, includes the following steps: S1.1: 25-35 parts by weight of modified natural plant fiber are pretreated with alkali solution in 2-5% sodium hydroxide solution at 80-90℃ for 1-2 hours to remove lignin and pectin. Then, the fiber is washed with deionized water until neutral and dried at 110-120℃ for 2-3 hours. S1.2: The treated plant fibers are melt-mixed with 12-20 parts by weight of polylactic acid resin and 8-15 parts by weight of bio-based plasticizer in a twin-screw extruder at 140-150°C for 15-20 minutes; S1.3: Add 0.3-1.2 parts by weight of covalently anchored organosilicon quaternary ammonium salt insect repellent to the molten mixture, and continue reactive mixing at 140-150℃ for 10-15 minutes to allow its active end groups to chemically bond with the substrate; S1.4: After the reaction is complete, add 0.8-2.0 parts by weight of natural repellent, 0.5-1.5 parts by weight of interface compatibilizer and 0.3-0.8 parts by weight of processing aid in sequence, mix evenly at 130-140℃ for 10-15 minutes to obtain insect-resistant composite material.

[0013] Further, step S2 involves preparing the functional outer sheath material, including the following steps: S2.1: Preheat 30-40 parts by weight of polyvinyl chloride resin to 60-70℃ in a high-speed mixer, control the speed at 800-1000 rpm, and mix for 5-10 minutes; S2.2: Add 0.8-1.5 parts by weight of biological protective additive and 0.5-1.5 parts by weight of shielding functional pigment in sequence, and continue mixing for 10-15 minutes; S2.3: Add 0.4-1.0 parts by weight of wear-resistant modifier and 1.0-2.0 parts by weight of heat stabilizer, and mix at high speed for 15-20 minutes at 70-80℃; S2.4: Cool the mixture to room temperature and sieve to obtain the functional outer sheath material.

[0014] Further, step S3, preparing the cable, includes the following steps: The aluminum alloy wire undergoes acid and alkali washing surface treatment, followed by spraying a polytetrafluoroethylene (PTFE) micro-powder coating onto its surface. Then, a cross-linked polyethylene (XLPE) insulation layer is extruded over the aluminum alloy core at a temperature of 160-190℃. Next, an aluminum foil shielding layer is wrapped over the XLPE insulation layer, ensuring a tight fit between the shielding layer and the XLPE insulation layer. Insect-resistant composite material and functional outer sheath material are simultaneously extruded using co-extrusion equipment at a temperature of 155-170℃, forming an inner biological barrier protective layer with a thickness of 1.5-3.5mm and an outer functional sheath layer with a thickness of 0.5-1.5mm. Finally, the cooling water temperature is controlled at 15-25℃, and the cooling rate is 2-5m / min for shaping, resulting in a biological barrier rodent-proof and ant-proof aluminum alloy core cable.

[0015] Furthermore, the thickness of the cross-linked polyethylene insulation layer is 1.0-4.0 mm, preferably 2.0-2.5 mm; the thickness of the polytetrafluoroethylene micro powder coating is 5-15 μm.

[0016] Furthermore, the modified natural plant fiber is a natural fiber surface-modified with a silane coupling agent, wherein the natural fiber is one of bamboo fiber, eucalyptus fiber, or pine fiber, with an aspect ratio of 15-40; the bio-based plasticizer is specifically one or more combinations of tributyl citrate or acetylated tributyl citrate.

[0017] Based on the above technical means, surface modification of silane coupling agents can improve the interfacial bonding performance between plant fibers and polymer matrices and enhance the mechanical strength of composite materials; selecting natural fibers with specific aspect ratios ensures both reinforcement and avoids processing difficulties; the use of bio-based plasticizers further improves the biocompatibility and degradability of the system.

[0018] Furthermore, the covalently anchored organosilicon quaternary ammonium salt insect repellent is specifically an amino-functionalized polysiloxane quaternary ammonium salt; the natural repellent component is prepared by compounding pyrethroid extract, eucalyptus oil and β-cyclodextrin inclusion complex in a mass ratio of 1:2:1, wherein the total content of pyrethrin I and pyrethrin II in the natural pyrethroid extract is ≥25%, and the content of eucalyptol in the eucalyptus oil is ≥80%.

[0019] Furthermore, the covalently anchored organosilicon quaternary ammonium salt insect repellent is prepared by the following method: amino-terminated polydimethylsiloxane and quaternary ammonium salt compound are reacted at 90-110°C for 2-4 hours in the presence of a catalyst to obtain an amino-functionalized polysiloxane quaternary ammonium salt with a molecular weight of 8000-30000 Da, 2-4 amino active end groups / molecule, and a quaternary ammonium group content of 0.8-2.5 mmol / g.

[0020] Furthermore, the β-cyclodextrin-eucalyptol inclusion complex is prepared by an inclusion process: β-cyclodextrin is dissolved in hot water at 80°C, eucalyptol is slowly added, the mixture is stirred at 75-80°C for 4 hours, cooled and crystallized, and then dried, with an inclusion rate of 60-70%.

[0021] Based on the above technical means, the amino active end group provides covalent bonding ability with the substrate, ensuring the long-term fixation of the insecticide; the quaternary ammonium group provides broad-spectrum antibacterial and insecticidal activity; natural pyrethroids provide highly efficient insect repellent activity, eucalyptus oil has good rodent repellent effect, and β-cyclodextrin inclusion technology realizes the sustained release and stabilization of active ingredients.

[0022] Furthermore, the interface compatibilizer is prepared by compounding maleic anhydride-grafted polylactic acid, chlorinated polyethylene-g-maleic anhydride, epoxidized soybean oil and silane coupling agent KH-550 in a mass ratio of 2-4:1-2:1-3:0.5-1.5, preferably in a mass ratio of 3:1.5:2:1.

[0023] Based on the above technical means, maleic anhydride-grafted polylactic acid provides bio-based compatibility, chlorinated polyethylene-g-maleic anhydride improves compatibility with PVC, and silane coupling agent provides chemical coupling effect. The synergistic effect of the four ensures the interfacial bonding strength between heterogeneous materials.

[0024] Further, the processing aid is prepared by compounding lubricant, antistatic agent and flow improver in a mass ratio of 2-4:1-3:2-4, preferably in a mass ratio of 3:2:3; further, the biological protective additive is prepared by compounding hydrophobically modified chitosan, tea polyphenols and limonene in a mass ratio of 2-4:1-3:0.5-2, preferably in a mass ratio of 3:2:1; the wear-resistant modifier is one or more combinations of nano-alumina, polytetrafluoroethylene micro powder and nano-silica, with an average particle size of 50-200 nm; the heat stabilizer is prepared by compounding calcium-zinc composite stabilizer, β-diketone synergistic stabilizer and phosphite antioxidant in a mass ratio of 8-12:3-5:2-4, preferably in a mass ratio of 10:4:3.

[0025] Furthermore, the lubricant is one or more of calcium stearate and paraffin wax; the antistatic agent is one or more of quaternary ammonium salt antistatic agents and sulfonate antistatic agents; and the flow improver is one or more of polyethylene wax, oxidized polyethylene wax, and montmorillonite modifier.

[0026] Further, the preparation method of the hydrophobic modified chitosan derivative is as follows: chitosan is dissolved in acetic acid solution, heated to 50-70℃, the pH value is adjusted to 8.5-9.5, octadecyl chloride or silane coupling agent modifier is added under stirring, the reaction is carried out for 4-8 hours, and after precipitation, washing and drying, hydrophobic modified chitosan with a modification degree of 15-35% is obtained.

[0027] Based on the above technical means, the compounding of processing aids ensures the good processing performance of the material; the hydrophobic modified chitosan derivatives, modified by octadecyl or silane coupling agents, not only maintain the natural antibacterial properties of chitosan, but also solve the dispersion problem of it in the hydrophobic PVC matrix; the heat stabilizer system provides the material with excellent thermal stability and antioxidant properties.

[0028] Furthermore, the shielding functional pigment is specifically one or more combinations of indium tin oxide, doped rare earth oxide, and doped titanium dioxide, with a particle size distribution D50 of 80-150 nm.

[0029] Furthermore, the shielding functional pigment has a blocking rate of ≥95% for 200-400nm ultraviolet light and a reflectivity of ≥70% for 800-1200nm near-infrared light, providing comprehensive spectral protection for the cable.

[0030] Based on the above technical means, the shielding functional pigments, through nanoscale particle size design, not only ensure good dispersibility, but also provide excellent ultraviolet light blocking and near-infrared light reflection functions, providing comprehensive spectral protection for cables.

[0031] Furthermore, a bio-barrier rodent-proof and ant-proof aluminum alloy core cable is prepared by the above-mentioned preparation process of the bio-barrier rodent-proof and ant-proof aluminum alloy core cable.

[0032] The beneficial effects of this invention are as follows: 1. A two-layer synergistic protection system constructs a three-dimensional biological barrier. The inner insect-resistant composite material provides durable protection through chemical repellency and covalent anchoring, while the outer functional sheath provides physical barrier and spectral shielding. This dual-layer synergistic protection system reduces the area affected by biological attack, offering a significant improvement over traditional single-protection methods and providing reliable assurance for the long-term stable operation of cables in biologically infested environments.

[0033] 2. Covalent anchoring technology enables the persistent fixation of insecticides. Amino-functionalized polysiloxane quaternary ammonium salt insect repellents form stable covalent bonds with the polymer substrate through chemical bonding of the amino active end groups. This covalent anchoring technology effectively reduces the precipitation and loss of active ingredients, improving the durability of the protective effect. The insecticidal effect remains stable during long-term use, solving the technical problems of easy volatility and short-lasting effect of repellents in existing technologies.

[0034] 3. The combination of natural repellent ingredients achieves broad-spectrum and highly effective biological repellency. Natural pyrethroid extracts exhibit highly effective repellent activity against insects, while eucalyptus oil demonstrates significant repellency against rodents. β-cyclodextrin inclusion technology enables sustained release and stabilization of the active ingredients. The three components work synergistically to cover major sources of biological attack, achieving a "one-dose-multiple-effects" protective effect, offering a broader protective spectrum and longer-lasting protection compared to single-component formulations.

[0035] 4. Bio-based material systems balance the dual requirements of performance and environmental protection. Modified natural plant fibers enhance the mechanical strength of the composite material, while the polylactic acid matrix and bio-based plasticizer provide excellent biodegradability. Hydrophobically modified chitosan retains its natural antibacterial properties while resolving dispersion issues in the hydrophobic matrix. The entire material system meets the stringent requirements of cable applications while achieving environmental friendliness and aligning with green development principles.

[0036] 5. Interface engineering design ensures the compatibility and synergy between heterogeneous materials. The bio-based PVC multi-component interface compatibilizer effectively solves the compatibility problem between bio-based materials and traditional PVC matrices through a quadruple mechanism of maleic anhydride grafting, chlorinated polyethylene modification, epoxidized soybean oil toughening, and silane coupling agent chemical anchoring, ensuring the overall performance and long-term stability of the composite system. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements, and equivalents included within the scope of the claims.

[0038] Description of raw materials and equipment used in this invention: Modified natural plant fiber: Fujian Nanping Bamboo Industry Technology Co., Ltd., bamboo fiber, modified with KH-550 silane coupling agent, aspect ratio 25±3; Polylactic acid resin: NatureWorks, USA, brand name Ingeo 4043D, melt index 15g / 10min; Epoxidized soybean oil: Henan Aojixing Biotechnology Co., Ltd., epoxy value ≥6.0; Tributyl citrate: Zhejiang Jiashan Chemical Co., Ltd., industrial grade, purity ≥99%; Amino-functionalized polysiloxane quaternary ammonium salt: Jiangsu Aoshen New Material Co., Ltd., molecular weight 25000Da, amino functionality 3 per molecule; Natural pyrethroid extract: Yunnan Dianhong Pharmaceutical Group Co., Ltd., pyrethroid I+II content 30%; Eucalyptus oil: Guangxi Wuzhou Pine Resin Co., Ltd., eucalyptus oil content 85%; β-Cyclodextrin: Shandong Bailong Chuangyuan Biotechnology Co., Ltd., pharmaceutical grade; Polyvinyl chloride resin: Xinjiang Tianye Co., Ltd., grade SG-5, K value 67; Chitosan: Qingdao Xinchangping Marine Biotechnology Co., Ltd., degree of deacetylation ≥90%; Octadecyl chloride: Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade; Indium tin oxide: Ningbo Jizhi Technology Co., Ltd., particle size 120nm; All other raw materials are industrial-grade or analytical-grade reagents, purchased through legitimate channels.

[0039] Phase 1: Preparation of β-cyclodextrin-eucalyptol inclusion complex Dissolve 30g of β-cyclodextrin in 200mL of 80℃ hot water and stir until completely dissolved and clear. Slowly add 15g of eucalyptol at a dropping rate of approximately 1mL / min while maintaining a stirring speed of 300r / min. Maintain the reaction temperature at 75-80℃ and stir for 4 hours to ensure complete inclusion. After the reaction is complete, allow to cool naturally to room temperature, and white crystals will precipitate. Collect the crystals by filtration, wash twice with a small amount of cold water, and dry in a vacuum drying oven at 60℃ for 12 hours to obtain the β-cyclodextrin-eucalyptol inclusion complex with an inclusion rate of 65% and a moisture content ≤3%.

[0040] Phase Two: Preparation of Covalently Anchored Insecticides In a three-necked flask equipped with a reflux condenser and nitrogen protection, 100 g of amino-terminated polydimethylsiloxane (2-4 amino functional groups / molecule) and 80 g of dodecyl dimethyl benzyl ammonium chloride were added. 0.5 g of triethylamine was added as a catalyst, and the reaction was carried out at 100 ± 2 °C for 3 hours under nitrogen protection. During the reaction, the amino groups of the amino-terminated siloxane underwent nucleophilic substitution with the quaternary ammonium salt molecule to form covalently bonded quaternary ammonium salt functionalized polysiloxane. After the reaction was completed, the mixture was cooled to room temperature, washed three times with anhydrous ethanol to remove unreacted raw materials, and dried under vacuum at 60 °C for 12 hours to obtain 175 g of a pale yellow, viscous amino-functionalized polysiloxane quaternary ammonium salt with a molecular weight of 25000 Da, retaining 3 amino active terminal groups / molecule, and a quaternary ammonium group content of 2.0 mmol / g.

[0041] Phase 3: Preparation of hydrophobically modified chitosan 50 g of chitosan was added to 500 mL of 1% acetic acid solution and stirred at room temperature for 8 hours until completely dissolved, yielding a clear chitosan-acetic acid solution. 15 g of octadecyl chloride was dissolved in 50 mL of anhydrous ethanol to prepare a modifier solution. In a reactor equipped with a mechanical stirrer and a thermostat, the chitosan solution was heated to 60 °C, and the pH was adjusted to 9.0 ± 0.2 with sodium hydroxide solution. The modifier solution was slowly added dropwise over 45 minutes with vigorous stirring (400 rpm). The reaction temperature was maintained at 60 °C, and the reaction was stirred for 6 hours. After the reaction was complete, the mixture was cooled to room temperature, and the product was precipitated with acetone. The precipitate was collected by filtration, washed successively with distilled water and ethanol until neutral, and then dried under vacuum at 50 °C for 24 hours to obtain 45 g of hydrophobically modified chitosan with a modification degree of 25%.

[0042] Phase 4: Preparation of interfacial compatibilizers In a reaction vessel equipped with a high-speed disperser, add 3 parts of maleic anhydride-grafted polylactic acid, 1.5 parts of chlorinated polyethylene-g-maleic anhydride, and 2 parts of epoxidized soybean oil in sequence. Stir at 1000 rpm for 15 minutes at room temperature to initially mix the components. Then add 1 part of silane coupling agent KH-550, increase the stirring speed to 1500 rpm, and continue mixing for 30 minutes. Control the temperature not to exceed 40℃ during mixing to avoid component decomposition. After mixing, sieve through a 100-mesh sieve to obtain 7.5 parts of uniform interfacial compatibilizer powder with a particle size ≤200 mesh and a light yellow appearance.

[0043] Phase 5: Compound of natural repellent ingredients In a temperature-controlled mixing container, natural pyrethroid extract, eucalyptus oil, and the β-cyclodextrin-eucalyptol inclusion complex prepared in the first stage were weighed in a weight ratio of 1:2:1. First, the eucalyptus oil was mixed with the pyrethroid extract at 30°C with a stirring speed of 200 rpm for 20 minutes until homogeneous. Then, the inclusion complex was gradually added, and the stirring speed was increased to 400 rpm, mixing for 30 minutes to ensure uniform dispersion. The temperature was controlled to ≤35°C throughout the mixing process to avoid loss of volatile components. Finally, four parts of a compound natural repellent were obtained, appearing as a pale yellow powder with a characteristic natural fragrance.

[0044] Phase 6: Preparation of Insect-Resistant Composite Materials Insect-resistant composite materials were prepared in a twin-screw extruder equipped with a temperature control system and a high-intensity mixing device. First, 30 parts by weight of modified bamboo fiber (commercially available) were added to the first hopper, and the preheating temperature was set to 120°C for drying pretreatment for 15 minutes.

[0045] 16 parts by weight of polylactic acid resin and 11.5 parts by weight of tributyl citrate were added to the second hopper in a specific ratio and melt-mixed in a twin-screw extruder at 145°C. The screw speed was set to 45 r / min, the feeding rate was 10 kg / h, and the mixing time was 18 minutes. The temperature control accuracy was ±2°C to ensure that the polymer was fully melted without degradation.

[0046] 0.75 parts by weight of covalently anchored insecticide were continuously added to the molten mixture, and reactive mixing was continued at 145°C. The screw speed was increased to 55 r / min, and the reaction time was 12 minutes to allow the amino active end groups to chemically bond with the substrate. Torque changes were monitored during mixing to ensure complete reaction.

[0047] In the final stage, 1.4 parts by weight of natural repellent component, 1.0 parts by weight of interface compatibilizer, and 0.55 parts by weight of processing aid (prepared by compounding lubricant, antistatic agent, and flow improver in a mass ratio of 3:2:3, specifically calcium stearate, quaternary ammonium salt antistatic agent, and polyethylene wax) are added sequentially. The temperature is lowered to 135℃, the screw speed is adjusted to 40 r / min, and the mixing time is 12 minutes. After completion, the mixture is rapidly cooled to below 80℃ in a cooling water tank, and granulated to obtain insect-resistant composite material particles with a particle size of 3-5 mm, a light green appearance, and a slight plant fragrance.

[0048] Phase 7: Preparation of Functional Outer Sheath Materials The functional outer sheath material was prepared in a high-speed mixer equipped with a variable frequency speed control system and a temperature control device. 35 parts by weight of polyvinyl chloride resin were added to the mixing tank, preheated to 65°C, and the speed was set to 900 r / min. The mixture was then premixed under no-load for 5 minutes to remove moisture.

[0049] Slowly add 1.15 parts by weight of a bioprotective additive (prepared by compounding hydrophobically modified chitosan, tea polyphenols, and limonene in a mass ratio of 3:2:1) to the preheated PVC resin. Maintain a rotation speed of 900 r / min and a temperature of 65℃, and mix for 8 minutes to ensure the bioprotective additive is fully dispersed.

[0050] Next, add 1.0 part by weight of ITO functional pigment (indium tin oxide), paying attention to the uniform dispersion of the pigment during the mixing process. Maintain a speed of 900 r / min and a mixing time of 12 minutes, stopping the machine every 3 minutes to check the dispersion status and ensure that there are no obvious particles or color spots.

[0051] Subsequently, 0.7 parts by weight of wear-resistant modifier (nano-alumina) and 1.5 parts by weight of heat stabilizer compound (prepared by compounding calcium-zinc composite stabilizer, β-diketone synergistic stabilizer, and phosphite antioxidant in a mass ratio of 10:4:3) were added. The temperature was raised to 75°C, and the mixing speed was maintained at 900 r / min for 18 minutes. During the mixing process, samples were taken periodically to detect changes in melt flow index and color to ensure that the stabilizer was fully effective.

[0052] After mixing, the cooling system is activated, and the mixture is cooled to room temperature while stirring. The mixture is then sieved through a 120-mesh sieve to obtain a free-flowing functional outer sheath material powder. The powder is grayish-white in appearance, free of lumps, and has a uniform particle size.

[0053] Phase 8: Cable Preparation The preparation of bio-barrier rodent- and termite-proof aluminum alloy core cables was carried out on a continuous cable production line. First, the surface of the 2.5mm diameter aluminum alloy wire was pretreated: it was acid-washed with 5% sulfuric acid solution for 2 minutes, then alkaline-washed with 3% sodium hydroxide solution for 1 minute, and finally rinsed with deionized water until neutral and dried.

[0054] A polytetrafluoroethylene (PTFE) micro-powder coating was applied to the pretreated aluminum alloy surface using plasma spraying equipment. Spraying parameters were: plasma gas flow rate 45 L / min, spraying power 35 kW, spraying distance 120 mm, substrate preheating temperature 150 °C, and coating thickness controlled at 10 ± 2 μm. After spraying, the coating was sintered in an oven at 380 °C for 30 minutes.

[0055] A 2.0 mm thick cross-linked polyethylene (XLPE) insulation layer was applied using a three-layer co-extrusion machine. Extrusion parameters: die head temperature 190℃, die body temperature 180℃, traction speed 15 m / min, cooling water temperature 25℃. Immediately after the XLPE insulation layer was applied, an aluminum foil shielding layer was applied, ensuring an overlap rate ≥15% and a tight, air-free fit with the XLPE insulation layer.

[0056] The insect-resistant composite material prepared in the sixth stage and the functional outer sheath material prepared in the seventh stage were simultaneously extruded using a co-extrusion device. The co-extrusion device used a twin-screw extruder as the main extruder, equipped with a co-extrusion die head, and the extrusion temperature was controlled at 162±3℃. The extrusion parameters for the inner insect-resistant composite material were: screw speed 48 r / min, material residence time 10 minutes; the extrusion parameters for the outer functional sheath material were: screw speed 42 r / min, residence time 8 minutes.

[0057] During the extrusion process, the flow ratio of the inner and outer layers is controlled at 2.5:1, and the traction speed is 12 m / min, forming an inner biological barrier protective layer with a thickness of 2.5 ± 0.2 mm and an outer functional sheath layer with a thickness of 1.0 ± 0.1 mm. The eccentricity during the extrusion process is strictly controlled to ≤5% to ensure uniform thickness.

[0058] The extruded cable immediately enters the cooling system for shaping. The cooling water temperature is controlled at 20±2℃, and the cooling rate is 3.2m / min. After shaping, the cable is wound up, with the coil diameter ≥ 20 times the cable's outer diameter to avoid excessive bending stress. The finished cable is light gray in appearance, with a smooth surface, good bending performance, and a slight natural plant fragrance, indicating the presence of bio-barrier function. Example 1

[0059] The preparation process is basically the same as in Example 1, with the main difference being that the raw material ratio is taken as the lower limit of the claims: 25 parts modified natural plant fiber, 12 parts polylactic acid resin, 8 parts bio-based plasticizer, 0.3 parts covalently anchored insect repellent, 0.8 parts natural repellent component, 0.5 parts interface compatibilizer, 0.3 parts processing aid, 30 parts PVC resin, 0.8 parts biological protective additive, 0.5 parts functional pigment, 0.4 parts wear-resistant modifier, and 1.0 part heat stabilizer.

[0060] In terms of the preparation process, since the amounts of each component are at the lower limit, precise control of the ingredient proportioning and mixing process is required. For the preparation of insect-resistant composite materials, the melt mixing time is extended to 20 minutes, and the reactive mixing time is extended to 15 minutes to ensure good dispersion and reaction effects even at low component contents. For the preparation of functional outer sheath materials, the mixing time is correspondingly extended by 2-3 minutes to ensure uniform dispersion. Example 2

[0061] The preparation process is basically the same as in Example 1, with the main difference being that the raw material ratio is taken at the upper limit of the claims: 35 parts modified natural plant fiber, 20 parts polylactic acid resin, 15 parts bio-based plasticizer, 1.2 parts covalently anchored insect repellent, 2.0 parts natural repellent component, 1.5 parts interface compatibilizer, 0.8 parts processing aid, 40 parts PVC resin, 1.5 parts biological protective additive, 1.5 parts functional pigment, 1.0 part wear-resistant modifier, and 2.0 parts heat stabilizer.

[0062] In terms of the preparation process, due to the high content of fillers and insecticides, the viscosity of the system increases, requiring appropriate adjustments to process parameters. The screw speed of the twin-screw extruder was reduced to 40 r / min to ensure thorough mixing. The speed of the high-speed mixer was increased to 1000 r / min, and the mixing time was extended to 20 minutes to avoid agglomeration caused by excessively high local concentrations. Example 3

[0063] The preparation process was basically the same as in Example 1, with the main difference being the use of eucalyptus fiber instead of bamboo fiber and the use of acetylated tributyl citrate instead of tributyl citrate as the bio-based plasticizer. Other parameters remained the same as the median ratio in Example 1. The modified eucalyptus fiber was also commercially available and modified with KH-550 silane coupling agent, with an aspect ratio of 20±3, and its processing performance was comparable to that of modified bamboo fiber. Example 4

[0064] The preparation process was basically the same as in Example 1, with the main adjustment being that the amount of covalently anchored insecticide was 1.0 part and the amount of natural repellent component was 1.4 parts, to verify the effect of insecticide dosage on the bioprotective effect. Other parameters remained unchanged. Due to the increased insecticide dosage, the reactive mixing time was shortened to 10 minutes to avoid over-reaction. Example 5

[0065] The preparation process was basically the same as in Example 1, except that doped titanium dioxide was used instead of indium tin oxide as the shielding functional pigment, with a particle size distribution D50 of 100 nm. In the bioprotective additive, silane coupling agent-modified chitosan was used instead of octadecyl-modified chitosan to verify the effects of different modification methods and functional pigments. All other conditions remained the same. Example 6

[0066] The preparation process was basically the same as in Example 1, except that the amount of the natural repellent ingredient was adjusted to 1.8 parts to verify the effect of the repellent ingredient amount on the biobarrier performance. The covalently anchored insecticide was kept at 0.75 parts, and other parameters remained unchanged. Due to the increased amount of repellent ingredient, the mixing time in the fifth stage needed to be appropriately extended to 25 minutes to ensure uniform dispersion of the active ingredients.

[0067] Comparative Example 1 The preparation process was the same as in Example 1, but the covalently anchored organosilicon quaternary ammonium salt insecticide was completely removed, and the amount of polylactic acid resin was adjusted to 16.75 parts to maintain the total amount, thus verifying the key role of the covalently anchored insecticide technology.

[0068] Comparative Example 2 The preparation process was the same as in Example 1, but the natural repellent component was removed and replaced with an equal amount of ordinary calcium carbonate filler to verify the contribution of the natural repellent component to the biobarrier performance.

[0069] Comparative Example 3 The preparation process was the same as in Example 1, but the modified natural plant fiber was replaced with an equal amount of unmodified ordinary bamboo fiber to verify the necessity of surface modification of the silane coupling agent.

[0070] Comparative Example 4 The preparation process was the same as in Example 1, but the hydrophobic modified chitosan was replaced with an equal amount of ordinary chitosan to verify the effect of hydrophobic modification on dispersibility and antibacterial properties in PVC matrix.

[0071] Performance testing

[0072] Insect resistance test: A biological infestation test method was established based on relevant biological material testing standards. A 500mm long cable sample was placed in a standard 1000mm×600mm×400mm biological test chamber containing 20 termite worker ants and 5 mice. The temperature was controlled at 25±2℃ and the relative humidity at 75±5%. Standard feed was provided daily during the test, and observation continued for 30 days. Infestation was photographed and recorded every 7 days. After the test, the infested area was measured using calipers, and the percentage of infested area relative to the total outer surface area of ​​the cable was calculated. Before testing, the cable surface was ensured to be clean and free of oil and foreign matter.

[0073] Tensile strength test: The test was conducted using the standard method of GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General rules" and a CMT4104 universal testing machine. Standard dumbbell-shaped specimens were prepared from the cable sheath layer, with a specimen thickness of 2.0±0.2 mm and a gauge length of 50 mm. Under standard laboratory conditions (temperature 23±2℃, relative humidity 50±5%), the specimens were clamped in the testing machine, and the tensile speed was set to 50 mm / min, continuously stretched until the specimen broke. The maximum tensile force and elongation at break were recorded, and the tensile strength and elongation at break were calculated. Five specimens were tested in each group, and the average value was taken.

[0074] Bending performance test: The bending test method in GB / T 12527-2008 "Copper and Aluminum Core Polyvinyl Chloride Insulated Cables with Rated Voltage of 1kV and Below" was adopted. A 1000mm long cable sample was pretreated at -40±2℃ for 4 hours, and then tested using a bending test device. The bending radius was set to 4 times the cable outer diameter, the bending angle to 90°, and the bending speed to 10 times / min. Bending continued until cracks appeared in the cable sheath or internal wire breaks, and the number of bends was recorded. The conductivity and insulation performance of the cable were checked before and after the test to ensure that the electrical performance was intact.

[0075] Flame retardant performance test: The vertical flammability test was conducted using the standard method of GB / T 18380.12-2022 "Cables and optical cables - Flame test - Part 12: Vertical flame spread test for bundled wires or cables installed vertically". Three cable samples, each 3500mm in length, were vertically mounted on a standard test frame, with the center-to-center spacing between the cables being the cable outer diameter plus 10mm. A 20.5±2kW propane Bunsen burner was used to apply a flame vertically at a distance of 1000mm from the bottom of the cable for 20 minutes. After combustion, the flame spread height was observed, and the length of the charred and damaged areas was measured. The flame retardant rating was assessed according to GB / T 18380.12 standard: Class A requires a charred length ≤ 2.5m; Class B requires a charred length ≤ 2.5m and the cable maintaining circuit integrity after the test; Class C requires a charred length ≤ 2.5m and no burning drips igniting the indicator paper.

[0076] Insulation resistance test: The test was conducted according to the standard method of GB / T 3048.5-2007 "Test Methods for Electrical Properties of Wires and Cables - Part 5: Insulation Resistance Test". A 100m cable sample was immersed in a constant temperature water bath at 20±2℃ for 24 hours. A DC voltage of 500V was applied using a ZC36 megohmmeter to test the insulation resistance between the conductor and the sheath. The test time was 1 minute, and a stable value was recorded. Before the test, ensure that the cable surface was dry and clean and the connection was reliable. The volume resistivity ρ was calculated as ρ = R × A / L, where R is the insulation resistance, A is the cross-sectional area of ​​the cross-linked polyethylene insulation layer, and L is the test length.

[0077] Biodegradability test: The biodegradability was determined according to GB / T 19277.1-2011 "Determination of the final aerobic biodegradation capacity of materials under controlled composting conditions by measuring the amount of carbon dioxide released". Cable sheath material samples were prepared into 2mm × 2mm × 1mm pieces, weighed, and placed in a closed reactor containing mature compost. Reaction conditions: temperature 58±2℃, relative humidity 55±5%, pH 7.0±0.5, with regular agitation to maintain aerobic conditions. Infrared radiation was applied every 3 days during the experiment. The analyzer measures the released The amount was monitored continuously for 90 days. A positive control for cellulose and a blank negative control were also set up.

[0078] Calculate the biodegradation rate = .

[0079] Performance Test Comparison Table

[0080] Data Analysis Example 1, using the median ratio of each component, achieved an excellent insecticidal effect of 0.3%, attributed to the optimal synergistic ratio of 0.75 parts covalently anchored insecticide and 1.4 parts natural repellent, avoiding aggregation and failure due to excessive dosage. In terms of mechanical properties, 30 parts of plant fiber achieved the optimal balance between reinforcement and dispersion, with a tensile strength of 32.5 MPa and a bending performance of 1680 cycles, both of which were optimal.

[0081] Examples 2-3 verified the technical feasibility of the lower and upper limits of the claims, respectively. In Example 2, performance decreased slightly at lower component contents but remained within acceptable limits. In Example 3, although a high-content formulation was used, 35 parts of plant fiber exceeded the dispersion limit of the matrix, resulting in fiber agglomeration, stress concentration, and a decrease in mechanical properties. Simultaneously, 1.2 parts of insect repellent exceeded the critical micelle concentration, forming large agglomerates, reducing dispersion and insecticidal activity. Examples 4 and 6 verified the technical feasibility of different raw material combinations. Example 4, using eucalyptus fiber and tributyl acetylacetonate, achieved performance comparable to the bamboo fiber system; Example 6, employing different modification methods and functional pigments, demonstrated the diversity of technical solutions.

[0082] Examples 5 and 7 verified the dosage effects of the insecticide and repellent, respectively. In Example 5, 1.0 part of the insecticide was slightly excessive compared to the optimal dosage of 0.75 parts, resulting in a slight aggregation effect and an insecticidal effect of 0.6%. In Example 7, 1.8 parts of the repellent was moderately increased compared to the optimal dosage of 1.4 parts, with an insecticidal effect of 0.7%, indicating that the repellent could still play an effective role at this dosage, but the marginal effect was diminishing.

[0083] Comparative Example 1 showed a significant increase in the infested area after the removal of the covalently anchored insecticide, fully demonstrating the key role of covalent anchoring technology. Comparative Example 2 showed an increased infested area after the removal of the natural repellent component, highlighting the importance of the natural repellent component. Comparative Example 3 showed a significant decrease in mechanical properties due to the use of unmodified fibers, verifying the necessity of surface modification. Comparative Example 4 showed a reduction in biodegradation rate due to the use of ordinary chitosan, confirming the technical advantages of hydrophobic modification.

[0084] Experimental results show that the present invention achieves excellent biobarrier performance and comprehensive performance through the synergistic effect of key technologies such as covalently anchored insecticides, compounding of natural repellent components, and modified plant fibers.

[0085] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a bio-barrier rodent- and termite-proof aluminum alloy core cable, characterized in that, The steps include the following: S1: Add 25-35 parts by weight of modified natural plant fiber and 12-20 parts by weight of polylactic acid resin to a twin-screw extruder and heat. Add 8-15 parts by weight of bio-based plasticizer and stir to mix. Then add 0.3-1.2 parts by weight of covalently anchored organosilicon quaternary ammonium salt insect repellent. After the mixing reaction is completed, add 0.8-2.0 parts by weight of natural repellent component, 0.5-1.5 parts by weight of interface compatibilizer and 0.3-0.8 parts by weight of processing aid, and mix evenly to obtain insect-resistant composite material. S2: Weigh 30-40 parts by weight of polyvinyl chloride resin and heat it. Then add 0.8-1.5 parts by weight of biological protective additive, 0.5-1.5 parts by weight of shielding functional pigment, 0.4-1.0 parts by weight of wear-resistant modifier and 1.0-2.0 parts by weight of heat stabilizer in sequence. Mix them in a high-speed mixer to obtain a functional outer sheath material. S3: Using aluminum alloy as the conductive core material, the outer surface of the conductive core material is coated with polytetrafluoroethylene micro powder coating, the polytetrafluoroethylene micro powder coating is covered with a cross-linked polyethylene insulation layer, the cross-linked polyethylene insulation layer is covered with a metal shielding layer, and then the insect-resistant composite material prepared in step S1 and the functional outer sheath material prepared in step S2 are extruded simultaneously, so that the insect-resistant composite material is covered on the outer surface of the metal shielding layer to form an inner biological barrier protective layer, and the functional outer sheath material is covered on the outer surface of the inner biological barrier protective layer to form an outer protective layer; Step S1, which involves preparing the insect-resistant composite material, includes the following steps: S1.1: 25-35 parts by weight of modified natural plant fiber are pretreated with alkali solution in 2-5% sodium hydroxide solution at 80-90℃ for 1-2 hours to remove lignin and pectin. Then, the fiber is washed with deionized water until neutral and dried at 110-120℃ for 2-3 hours. S1.2: The treated plant fibers are melt-mixed with 12-20 parts by weight of polylactic acid resin and 8-15 parts by weight of bio-based plasticizer in a twin-screw extruder at 140-150°C for 15-20 minutes; S1.3: Add 0.3-1.2 parts by weight of covalently anchored organosilicon quaternary ammonium salt insect repellent to the molten mixture, and continue reactive mixing at 140-150℃ for 10-15 minutes to allow its active end groups to chemically bond with the substrate; S1.4: After the reaction is complete, add 0.8-2.0 parts by weight of natural repellent, 0.5-1.5 parts by weight of interface compatibilizer and 0.3-0.8 parts by weight of processing aid in sequence, mix evenly at 130-140℃ for 10-15 minutes to obtain insect-resistant composite material; The covalently anchored organosilicon quaternary ammonium salt insect repellent is specifically an amino-functionalized polysiloxane quaternary ammonium salt with a molecular weight of 8000-30000 Da; the natural repellent component is prepared by compounding pyrethroid extract, eucalyptus oil, and β-cyclodextrin-eucalyptol inclusion complex in a weight ratio of 1:2:1; the interface compatibilizer is prepared by compounding maleic anhydride-grafted polylactic acid, chlorinated polyethylene-g-maleic anhydride, epoxidized soybean oil, and silane coupling agent KH-550. The modified natural plant fiber is a natural fiber surface-modified with a silane coupling agent. The natural fiber is one of bamboo fiber, eucalyptus fiber, and pine fiber, with an aspect ratio of 15-40. The bio-based plasticizer is specifically one or more combinations of tributyl citrate or acetylated tributyl citrate. The biological protective additive is prepared by compounding hydrophobically modified chitosan, tea polyphenols and limonene, wherein the hydrophobically modified chitosan is octadecyl-modified or silane coupling agent-modified chitosan.

2. The manufacturing process of the bio-barrier rodent-proof and termite-proof aluminum alloy core cable according to claim 1, characterized in that, Step S2 involves preparing the functional outer sheath material, including the following steps: S2.1: Preheat 30-40 parts by weight of polyvinyl chloride resin to 60-70℃ in a high-speed mixer, control the speed at 800-1000 rpm, and mix for 5-10 minutes; S2.2: Add 0.8-1.5 parts by weight of biological protective additive and 0.5-1.5 parts by weight of shielding functional pigment in sequence, and continue mixing for 10-15 minutes to ensure that the pigment is evenly dispersed; S2.3: Add 0.4-1.0 parts by weight of wear-resistant modifier and 1.0-2.0 parts by weight of heat stabilizer, and mix at high speed for 15-20 minutes at 70-80℃; S2.4: Cool the mixture to room temperature and sieve to obtain the functional outer sheath material.

3. The manufacturing process of the bio-barrier rodent-proof and termite-proof aluminum alloy core cable according to claim 1, characterized in that, The processing aid is prepared by compounding a lubricant, an antistatic agent, and a flow modifier; the lubricant is one or more of calcium stearate and paraffin wax; the antistatic agent is one or more of quaternary ammonium salt antistatic agents and sulfonate antistatic agents; and the flow modifier is one or more of polyethylene wax, oxidized polyethylene wax, and montmorillonite modifier.

4. The manufacturing process of the bio-barrier rodent-proof and termite-proof aluminum alloy core cable according to claim 1, characterized in that, The wear-resistant modifier is one or more of nano-alumina, polytetrafluoroethylene micro powder, and nano-silica, with an average particle size of 50-200 nm; the heat stabilizer is prepared by compounding calcium-zinc composite stabilizer, β-diketone synergistic stabilizer and phosphite antioxidant.

5. The manufacturing process of the bio-barrier rodent-proof and termite-proof aluminum alloy core cable according to claim 1, characterized in that, The shielding functional pigments are specifically one or more combinations of indium tin oxide (ITO), doped rare earth oxides, and doped titanium dioxide, with a particle size distribution D50 of 80-150 nm.

6. A bio-barrier rodent-proof and ant-proof aluminum alloy core cable, which is prepared by the preparation process of the bio-barrier rodent-proof and ant-proof aluminum alloy core cable according to any one of claims 1-5.

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