A flame-retardant, rodent-resistant, reinforced bundled insulated conductor

Abstract

The application discloses a reinforced bundled insulated conductor with fire-retardant and rat-bite prevention functions, and belongs to the field of insulated conductor preparation, and aims at the technical problem that the fire-retardant and rat-bite prevention performances of the insulated conductor need to be further improved, and specifically comprises a plurality of insulated cores, the plurality of insulated cores are arranged in parallel, and the plurality of insulated cores are externally coated with a fire-retardant and rat-bite prevention functional layer. The application is prepared by the following steps: activating halogen hydrochloric acid and halloysite nanotubes, vacuum-circulating and loading capsaicin, coating with melamine-cyanurate supermolecule and modifying by silane coupling, then melt blending, granulating with ethylene-vinyl acetate copolymer, maleic anhydride grafted elastomer and aluminum hydroxide, and finally, the insulated core is bundled and extruded with aramid fiber bundles to form a coating, so that the fire-retardant performance, rat-bite prevention performance and mechanical strength of the insulated conductor are improved.

Description

Technical Field

[0001] This invention relates to the field of insulated wire manufacturing, and specifically to a flame-retardant and rodent-resistant reinforced bundled insulated wire. Background Technology

[0002] Bundled insulated conductors are widely used in low-voltage power distribution and building electrical systems due to their advantages such as convenient wiring and high space utilization. With the improvement of electrical safety standards, flame retardant performance has evolved from simply delaying combustion to a comprehensive requirement of low smoke, low toxicity, and halogen-free. At the same time, in scenarios such as agricultural facilities, underground pipe corridors, and field installations, short circuit accidents caused by rodent gnawing are frequent. Rodent-proof performance has become a key indicator for the reliable service of bundled conductors. In recent years, bundled insulated conductors with both flame retardant and rodent-proof functions have become a research hotspot in the field of cable materials.

[0003] Currently, the flame-retardant and rodent-proof functions of bundled insulated conductors are mainly achieved through the following methods: In terms of flame retardancy, inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide are often used to fill ethylene-vinyl acetate copolymer or polyethylene matrix, or an intumescent flame retardant system of ammonium polyphosphate / pentaerythritol / melamine is used. In terms of rodent prevention, chemical repellents such as capsaicin and cyclohexylimide are often directly melt-blended with the sheath matrix, or rodent-proof coatings are applied to the outer layer of the cable. In some cases, stainless steel tape armor is used to physically resist biting. However, the above methods often apply flame retardancy and rodent prevention as independent functions. Direct blending of rodent repellents is prone to failure due to migration and volatilization. The large amount of inorganic flame retardant filling leads to the deterioration of the mechanical properties of the sheath, and the metal armor increases the weight and bending radius of the conductor, making it difficult to meet the application requirements of lightweight and flexible applications.

[0004] In existing technologies, when chemical repellents and inorganic flame-retardant fillers coexist in a polyolefin matrix, they lack effective interfacial isolation and synergistic carriers. Repellent molecules easily migrate to the surface and are lost upon contact with the environment, resulting in a sharp decline in rodent-repellent efficacy over service time. At the same time, the inorganic filler has a high surface polarity and poor compatibility with the polyolefin matrix, and uneven dispersion forms stress concentration points, causing a significant decrease in the tensile strength and elongation at break of the sheath. In addition, during the bundling process of bundled insulated wires, multiple insulated cores are arranged in parallel and then wrapped with a sheath. There is a lack of reinforcing skeleton between the sheath layer and the cores, resulting in insufficient overall tensile and bending deformation resistance of the wire. Under laying traction or external force, the sheath is prone to cracks that propagate along the interface, thereby losing its protective function for the internal conductor.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] This invention addresses the technical problem that the flame-retardant and rodent-proof properties of insulated wires in the prior art need further improvement.

[0007] The objective of this invention can be achieved through the following technical solution: a flame-retardant and rodent-proof reinforced bundled insulated wire, comprising several insulated wire cores arranged in parallel, and the insulated wire cores being covered with a flame-retardant and rodent-proof functional layer.

[0008] The insulated wire core consists of a metal conductor and an insulating layer from the inside out;

[0009] The metal conductor is made of multiple strands of bare copper wire twisted together;

[0010] The insulating layer is made by extruding cross-linked polyethylene onto the outside of the metal conductor;

[0011] By weight, the flame-retardant and rodent-proof functional layer comprises: 60-70 parts of ethylene-vinyl acetate copolymer, 15-25 parts of maleic anhydride-grafted polyolefin elastomer, 30-45 parts of halogen-free flame retardant, 10-15 parts of flame-retardant and rodent-proof modified halloysite, and 1-3 parts of auxiliary additives.

[0012] Furthermore, a tensile-strength fiber bundle is provided between two adjacent insulated wire cores, and the tensile-strength fiber bundle is covered by a flame-retardant and rodent-proof functional layer. The tensile-strength fiber bundle is an aramid fiber bundle.

[0013] Furthermore, the preparation method of the flame-retardant and rodent-proof modified halloysite is as follows: coated modified halloysite, deionized water and ethanol are placed in a reaction vessel and stirred. Glacial acetic acid aqueous solution is added to adjust the pH to 4-5. 3-aminopropyltriethoxysilane is added. The reaction vessel is heated to 40-50℃ and kept at this temperature for 2-4 hours. The flame-retardant and rodent-proof modified halloysite is then obtained after post-treatment.

[0014] Furthermore, the ratio of the coated modified halloysite, deionized water, ethanol, and 3-aminopropyltriethoxysilane is 8-10g:15-20mL:120-140mL:1-2g, and the concentration of the glacial acetic acid aqueous solution is 3-5wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with anhydrous ethanol, transferred to a vacuum drying oven at 60-70℃, and dried for 12-24h to obtain flame-retardant and rodent-resistant modified halloysite.

[0015] Furthermore, the coated modified halloysite is prepared using the following steps:

[0016] B1. Place halloysite nanotubes and hydrochloric acid aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 50-60℃ and keep it at the temperature for 2-4 hours. Post-treatment yields activated halloysite nanotubes.

[0017] B2. Place n-nonanoic vanillamide and ethanol in a reaction vessel and stir. Add activated halloysite nanotubes and stir to disperse for 30-60 min. Vacuum impregnate and post-treatment to obtain capsaicin-loaded halloysite.

[0018] B3. Place capsaicin-loaded halloysite and deionized water in a reaction vessel and stir. Heat the reaction vessel to 80-90℃, add cyanuric acid aqueous solution and melamine aqueous solution, heat the reaction vessel to 94-98℃, keep it at this temperature and stir for 2-4 hours, and then proceed with post-treatment to obtain coated modified halloysite.

[0019] Further, in step B1, the ratio of halloysite nanotubes to hydrochloric acid aqueous solution is 1g:15-20mL, and the concentration of hydrochloric acid aqueous solution is 5-10wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with deionized water until neutral, transferred to a vacuum drying oven at 50-60℃, and dried for 6-8h to obtain activated halloysite nanotubes.

[0020] Furthermore, in step B2, the ratio of the amount of n-nonanoic acid vanillamide, ethanol and activated halloysite nanotubes is 2-5g:150-200mL:9-11g. The post-treatment steps include: after impregnation, after the reaction solution cools to room temperature, centrifuge to collect the precipitate, wash the precipitate with ethanol 1-3 times, transfer it to a vacuum drying oven at 50-60℃, and dry it for 12-24h to obtain capsaicin-loaded halloysite.

[0021] Furthermore, in step B2, the vacuum impregnation step includes: after stirring and dispersing, transferring the suspension to a vacuum dryer, connecting a vacuum pump to perform repeated vacuuming and vacuum breaking cycles, with a vacuum degree of -0.08 to -0.1 MPa, a single vacuuming time of 10-15 min, and 3-5 cycles, with the system standing for 5 min after each vacuum breaking. After the cycle is completed, the system is placed in a constant temperature water bath at 40-50℃ and kept warm and stirred for 12-24 h. The post-treatment yields capsaicin-loaded halloysite.

[0022] Further, in step B3, the ratio of capsaicin-loaded halloysite, deionized water, cyanuric acid aqueous solution, and melamine aqueous solution is 10-12g:100-150mL:100-150mL:100-150mL. The cyanuric acid aqueous solution is obtained by mixing cyanuric acid and deionized water at a ratio of 4-6g:100-150mL. The melamine aqueous solution is obtained by mixing melamine and deionized water at a ratio of 4-6g:100-150mL. The temperature of both the cyanuric acid aqueous solution and the melamine aqueous solution is 94-96℃. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, stirred at room temperature for 1-2 hours, centrifuged, the precipitate is collected, the precipitate is washed 2-4 times with deionized water, transferred to a vacuum drying oven at a temperature of 50-60℃, and dried for 8-10 hours to obtain coated modified halloysite.

[0023] One method for preparing a flame-retardant and rodent-resistant reinforced bundled insulated wire includes the following steps:

[0024] S1. Ethylene-vinyl acetate copolymer, maleic anhydride grafted polyolefin elastomer, flame-retardant and rodent-proof modified halloysite and auxiliary additives are added to a high-speed mixer and mixed at high speed at 80-90℃ for 10-15 minutes. The mixture is then transferred to a twin-screw extruder for melt blending, extrusion granulation, and the resulting flame-retardant and rodent-proof polymer material particles are obtained.

[0025] S2. The metal conductor is led out through the wire feeding frame, passes through the first extruder, and an insulation layer is extruded on the outside of the metal conductor. After cooling in a water tank and being pulled, the wire is wound up to obtain the insulated wire core.

[0026] S3. Several insulated wire cores are introduced into the bundled co-extrusion die in parallel. Tensile reinforcing fiber bundles are introduced into the center of the gap between two adjacent insulated wire cores in the bundled co-extrusion die through a constant tension wire feeding device. Flame-retardant and rodent-proof polymer material particles are added to the second extruder to melt. The melt enters the bundled co-extrusion die and is extruded in one piece. After traction, cooling and shaping, and winding, a flame-retardant and rodent-proof reinforced bundled insulated wire is obtained.

[0027] Furthermore, in step S1, the length-to-diameter ratio of the twin-screw extruder is 36-48:1, the screw speed is 150-250 r / min, and the processing temperature of each section of the twin-screw extruder is controlled sequentially as follows: Zone 1 120-130℃, Zone 2 140-150℃, Zone 3 150-160℃, Zone 4 155-165℃, and the die head temperature 160-170℃.

[0028] Further, in step S1, the halogen-free flame retardant is one or more of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, and aluminum hypophosphite; the auxiliary additive is composed of lubricant, flame retardant synergist, antioxidant, and light stabilizer in a mass ratio of 4-5:1-2:2-3:1-2; the lubricant is one or more of ethylene bis-stearamide, polyethylene wax, and oxidized polyethylene wax; the flame retardant synergist is zinc borate or nano zinc oxide; the antioxidant is one or more of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and dilaurate thiodipropionate; and the light stabilizer is light stabilizer 944 or ultraviolet absorber UV-531.

[0029] Furthermore, in step S2, the extrusion temperature of the first extruder is 150-170℃, the extrusion line speed is 50-80m / min, and the water tank cooling adopts segmented warm water cooling, with the water temperature of each segment along the direction of the conductor travel being 60-70℃, 40-50℃ and room temperature respectively.

[0030] Furthermore, in step S3, the wire tension of the constant tension wire feeding device is controlled at 10-20N, the extrusion temperature of the second extruder is controlled at 155-175℃, the cooling and shaping adopts stepped water tank cooling, and the cooling water temperature along the direction of wire travel is successively 70-80℃, 50-60℃, 30-40℃ and room temperature, and the traction speed is 20-40m / min.

[0031] The present invention has the following beneficial effects:

[0032] 1. This invention involves activating and expanding halloysite nanotube cavities with hydrochloric acid to enrich surface hydroxyl groups. Capsaicin is then forced into the tubes via vacuum cycling to achieve nano-confined loading. Subsequently, melamine and cyanurate self-assemble through hydrogen bonds to form a melamine-cyanurate supramolecular coating layer to inhibit capsaicin migration. Furthermore, silane coupling introduces terminal amino groups that chemically bond with maleic anhydride-grafted elastomers. This multi-stage modification allows the rodent-repellent component to be released slowly and sustainably within the nanotube cavity. The melamine-cyanurate coating layer simultaneously imparts flame-retardant functions in both the condensed and gas phases. Moreover, the chemical bonding significantly improves the compatibility of the filler and matrix interface, enhancing the flame-retardant and rodent-repellent properties of the insulated wire sheath.

[0033] 2. In addition, aluminum hydroxide, zinc borate and melamine-cyanurate-coated halloysite are compounded in the ethylene-vinyl acetate copolymer matrix. Aluminum hydroxide absorbs heat and dilutes combustible gas upon heating and dehydration. Melamine-cyanurate sublimates and absorbs heat to form a non-combustible film. Halloysite nanotubes exert a barrier effect and promote the formation of a dense char layer. Zinc borate further catalyzes cross-linking to form char. The multiple components form a complementary flame retardant mechanism in the condensed phase and gas phase, which significantly reduces the heat release rate and increases the char residue rate, ensuring that the insulation wire sheath layer quickly forms a stable char layer barrier under combustion conditions.

[0034] 3. In addition, during the co-extrusion molding process, the aramid fiber bundles are accurately positioned at the center of the gap between adjacent insulated wire cores. The aramid fibers form an axially reinforcing skeleton in the sheath. The maleic anhydride-grafted elastomer disperses stress and improves the toughness of the matrix. The silane-modified halloysite strengthens the three-phase interface bonding of the sheath, insulated wire core and aramid fiber through the reaction of terminal amino groups with maleic anhydride. This structural design and the interfacial chemical bonding work synergistically to improve the tensile strength and elongation at break of the sheath. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the cross-sectional structure of the insulated wire of the present invention.

[0037] In the diagram: 1. Insulated wire core; 1-1. Metallic conductor; 1-2. Insulation layer; 2. Flame-retardant and rodent-proof functional layer; 3. Tensile-strength reinforcing fiber bundle. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The halloysite nanotubes used in this invention are commercially available products with an outer diameter of 50-100 nm, an inner diameter of 10-30 nm, a length of 500-2000 nm, and a specific surface area of ​​50-70 m². 2 / g;

[0040] The n-nonanoic acid vanillamide used in this invention is a commercially available product with a purity of ≥98%;

[0041] The ethylene-vinyl acetate copolymer used in this invention is a commercially available product with a vinyl acetate content of 18-28 wt% and a melt index of 2-10 g / 10 min.

[0042] The maleic anhydride-grafted polyolefin elastomer used in this invention is a commercially available product with a grafting rate of 0.5-1.5 wt%.

[0043] The aluminum hydroxide used in this invention is a commercially available product with a particle size D. 50 The thickness is 1-5 μm, and the specific surface area is 3-8 m². 2 / g;

[0044] The aramid fiber bundles used in this invention are commercially available products with a linear density of 200-400D and a breaking strength ≥20cN / dtex;

[0045] The cross-linked polyethylene used in this invention is a commercially available product with a density of 0.92-0.94 g / cm³. 3 The melt flow index is 0.5-2.0 g / 10 min.

[0046] Example 1

[0047] This embodiment provides a method for preparing coated modified halloysite, specifically including the following steps:

[0048] Step I: Preparation of activated halloysite nanotubes

[0049] Weigh 10g of halloysite nanotubes and 150mL of 5wt% hydrochloric acid aqueous solution and place them in a reaction vessel. Stir the reaction vessel and heat it to 50℃. Keep the temperature for 2h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake with deionized water until neutral, transfer it to a vacuum drying oven at 50℃ and dry it for 6h to obtain activated halloysite nanotubes.

[0050] Step II: Preparation of capsaicin-loaded halloysite

[0051] Weigh 20g of n-nonanoic acid vanillamide and 1500mL of ethanol and place them in a reaction vessel and stir. Add 90g of activated halloysite nanotubes and stir to disperse for 30min. Transfer the suspension to a vacuum desiccator and connect a vacuum pump to perform repeated vacuuming and vacuum breaking cycles. The vacuum degree is -0.08MPa, the vacuuming time is 10min per cycle, and the number of cycles is 3. After each vacuum breaking, let it stand for 5min. After the cycle is completed, place the system in a constant temperature water bath at 40℃ and keep it warm and stirred for 12h. After the reaction solution cools to room temperature, centrifuge to collect the precipitate. Wash the precipitate once with ethanol and transfer it to a vacuum drying oven at 50℃ and dry for 12h to obtain capsaicin-supported halloysite.

[0052] Step III: Preparation of coated modified halloysite

[0053] Mix melamine and deionized water at a ratio of 4g:100mL until homogeneous, heat to 94℃ to obtain melamine aqueous solution for later use.

[0054] The cyanuric acid aqueous solution is prepared by mixing cyanuric acid and deionized water at a ratio of 4g:100mL, heating to 94℃, and then setting aside.

[0055] Weigh 100g of capsaicin-loaded halloysite and 1000mL of deionized water and place them in a reaction vessel. Stir the reaction vessel and heat it to 80℃. Add 1000mL of cyanuric acid aqueous solution and 1000mL of melamine aqueous solution. Heat the reaction vessel to 94℃ and stir for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and stir at room temperature for 1 hour. Centrifuge and collect the precipitate. Wash the precipitate twice with deionized water and transfer it to a vacuum drying oven at 50℃. Dry for 8 hours to obtain coated modified halloysite.

[0056] Hydrochloric acid was used to etch halloysite nanotubes to remove impurities, expand the inner diameter of the cavity, and increase the surface hydroxyl density. Then, vanillamide nonanoic acid was pressed into the inner cavity and surface of the tubes through vacuum suction and vacuum breaking cycle to achieve loading. Subsequently, melamine and cyanuric acid self-assembled at high temperature through hydrogen bonding to form a melamine-cyanurate supramolecular layer, which was deposited and coated on the capsaicin-loaded halloysite surface to obtain coated modified halloysite.

[0057] Hydrochloric acid activates halloysite nanotubes to enrich hydroxyl groups, expand the lumen, strengthen interfacial bonding, and construct a loading space. Vacuum circulation promotes the intercalation of n-nonanoic acid vanillamide into the lumen, and controllable slow release is achieved by relying on the nano confinement effect. The melamine-cyanurate supramolecular layer is deposited through hydrogen bond self-assembly, which imparts flame retardancy to the condensed phase and gas phase and inhibits capsaicin migration, thus constructing a flame-retardant and rodent-proof dual-function barrier.

[0058] Example 2

[0059] This embodiment provides a method for preparing coated modified halloysite, specifically including the following steps:

[0060] Step I: Preparation of activated halloysite nanotubes

[0061] Weigh 10g of halloysite nanotubes and 175mL of 7.5wt% hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 55℃ and keep it at that temperature for 3h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake with deionized water until neutral, transfer it to a vacuum drying oven at 55℃ and dry it for 7h to obtain activated halloysite nanotubes.

[0062] Step II: Preparation of capsaicin-loaded halloysite

[0063] Weigh 35g of n-nonanoic acid vanillamide and 1750mL of ethanol and place them in a reaction vessel and stir. Add 100g of activated halloysite nanotubes and stir to disperse for 45min. Transfer the suspension to a vacuum desiccator and connect a vacuum pump to perform repeated vacuuming and vacuum breaking cycles. The vacuum degree is -0.09MPa, the vacuuming time is 13min per cycle, and the number of cycles is 4. After each vacuum breaking, let it stand for 5min. After the cycle is completed, place the system in a constant temperature water bath at 45℃ and keep it warm and stirred for 18h. After the reaction solution cools to room temperature, centrifuge to collect the precipitate. Wash the precipitate twice with ethanol and transfer it to a vacuum drying oven at 55℃ and dry for 18h to obtain capsaicin-loaded halloysite.

[0064] Step III: Preparation of coated modified halloysite

[0065] Mix melamine and deionized water at a ratio of 5g:125mL until homogeneous, heat to 95℃ to obtain melamine aqueous solution for later use.

[0066] The cyanuric acid aqueous solution is prepared by mixing cyanuric acid and deionized water at a ratio of 5g:125mL, heating to 96℃, and then setting aside.

[0067] Weigh 110g of capsaicin-loaded halloysite and 1250mL of deionized water and place them in a reaction vessel. Stir the reaction vessel and heat it to 85℃. Add 1250mL of cyanuric acid aqueous solution and 1250mL of melamine aqueous solution. Heat the reaction vessel to 95℃ and stir for 3 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and stir at room temperature for 1.5 hours. Centrifuge and collect the precipitate. Wash the precipitate three times with deionized water and transfer it to a vacuum drying oven at 55℃. Dry for 9 hours to obtain coated modified halloysite.

[0068] Example 3

[0069] This embodiment provides a method for preparing coated modified halloysite, specifically including the following steps:

[0070] Step I: Preparation of activated halloysite nanotubes

[0071] Weigh 10g of halloysite nanotubes and 200mL of 10wt% hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 60℃ and keep it at that temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake with deionized water until neutral, transfer it to a vacuum drying oven at 60℃ and dry it for 8h to obtain activated halloysite nanotubes.

[0072] Step II: Preparation of capsaicin-loaded halloysite

[0073] Weigh 50g of n-nonanoic acid vanillamide and 2000mL of ethanol and place them in a reaction vessel and stir. Add 110g of activated halloysite nanotubes and stir to disperse for 60min. Transfer the suspension to a vacuum desiccator and connect a vacuum pump to perform repeated vacuuming and vacuum breaking cycles. The vacuum degree is -0.1MPa, the vacuuming time is 15min per cycle, and the number of cycles is 5. After each vacuum breaking, let it stand for 5min. After the cycle is completed, place the system in a constant temperature water bath at 50℃ and keep it at this temperature for 24h with stirring. After the reaction solution cools to room temperature, centrifuge to collect the precipitate. Wash the precipitate 3 times with ethanol and transfer it to a vacuum drying oven at 60℃ and dry for 24h to obtain capsaicin-supported halloysite.

[0074] Step III: Preparation of coated modified halloysite

[0075] Mix melamine and deionized water at a ratio of 6g:150mL until homogeneous, heat to 96℃ to obtain melamine aqueous solution for later use.

[0076] The cyanuric acid aqueous solution is prepared by mixing cyanuric acid and deionized water at a ratio of 6g:150mL, heating to 96℃, and then setting aside.

[0077] Weigh 120g of capsaicin-loaded halloysite and 1500mL of deionized water and place them in a reaction vessel. Stir the reaction vessel and heat it to 90℃. Add 1500mL of cyanuric acid aqueous solution and 1500mL of melamine aqueous solution. Heat the reaction vessel to 98℃ and stir for 4 hours. After the reaction is complete, let the reaction system cool to room temperature and stir at room temperature for 2 hours. Centrifuge and collect the precipitate. Wash the precipitate 4 times with deionized water and transfer it to a vacuum drying oven at 60℃. Dry for 10 hours to obtain coated modified halloysite.

[0078] Example 4

[0079] This embodiment provides a method for preparing flame-retardant and rodent-resistant modified halloysite, specifically including the following steps:

[0080] Weigh out 80g of coated modified halloysite, 150mL of deionized water and 1200mL of ethanol and place them in a reaction vessel and stir. Add 3wt% glacial acetic acid aqueous solution to adjust the pH to 4, add 10g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 40℃ and keep it at that temperature for 2h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake twice with anhydrous ethanol, transfer it to a vacuum drying oven at 60℃ and dry it for 12h to obtain flame-retardant and rodent-proof modified halloysite.

[0081] In an acidic ethanol / water system, 3-aminopropyltriethoxysilane undergoes hydrolysis and condensation. Its silanol groups react with the hydroxyl groups on the surface of the modified halloysite to form Si-O-Si covalent bonds, completing the surface grafting of the aminosilane coupling agent and introducing reactive terminal amino groups to obtain flame-retardant and rodent-resistant modified halloysite.

[0082] The introduction of terminal amino groups imparts a reactive interface between halloysite and the insulating matrix resin, strengthens the interfacial adhesion between the filler and the matrix, improves dispersion uniformity and interfacial compatibility, and lays the chemical bonding foundation for subsequent composite processing.

[0083] Example 5

[0084] This embodiment provides a method for preparing flame-retardant and rodent-resistant modified halloysite, specifically including the following steps:

[0085] Weigh out 90g of coated modified halloysite, 1750mL of deionized water and 1300mL of ethanol and place them in a reaction vessel and stir. Add 4wt% glacial acetic acid aqueous solution to adjust the pH to 4.5, add 15g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 45℃ and keep it at that temperature for 3h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake three times with anhydrous ethanol, transfer it to a vacuum drying oven at 65℃ and dry it for 18h to obtain flame-retardant and rodent-proof modified halloysite.

[0086] Example 6

[0087] This embodiment provides a method for preparing flame-retardant and rodent-resistant modified halloysite, specifically including the following steps:

[0088] Weigh 100g of coated modified halloysite, 200mL of deionized water and 1400mL of ethanol and place them in a reaction vessel and stir. Add 5wt% glacial acetic acid aqueous solution to adjust the pH to 5, add 20g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 50℃ and keep it at that temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake 4 times with anhydrous ethanol, transfer it to a vacuum drying oven at 70℃ and dry it for 24h to obtain flame-retardant and rodent-proof modified halloysite.

[0089] Example 7

[0090] This embodiment provides a flame-retardant and rodent-proof reinforced bundled insulated wire, specifically including the following steps:

[0091] Step 1: Preparation of flame-retardant and rodent-proof polymer material particles

[0092] Ethylene bis-stearamide, zinc borate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and light stabilizer 944 were mixed evenly in a mass ratio of 4:1:2:1 to obtain an auxiliary additive for later use.

[0093] Weigh out the following by weight: 60 parts of ethylene-vinyl acetate copolymer, 15 parts of maleic anhydride grafted polyolefin elastomer, 15 parts of aluminum hydroxide, 10 parts of flame-retardant and rodent-proof modified halloysite prepared in Example 4, and 1 part of auxiliary additives. Add them to a high-speed mixer and mix at 80°C for 10 minutes. Transfer the mixture to a twin-screw extruder for melt blending, extrusion granulation, and obtain flame-retardant and rodent-proof polymer material particles.

[0094] The twin-screw extruder has a length-to-diameter ratio of 36:1 and a screw speed of 150 r / min. The processing temperatures of each section of the twin-screw extruder are controlled sequentially as follows: Zone 1 120℃, Zone 2 140℃, Zone 3 150℃, Zone 4 155℃, and the die head temperature 160℃.

[0095] Step 2: Preparing the Insulated Wire Core

[0096] The metal conductor 1-1 is led out through the wire feeding frame and passed through the first extruder. The extrusion temperature is controlled at 150℃ and the extrusion speed is 50m / min. An insulation layer 1-2 is extruded onto the outside of the metal conductor 1-1. Then, it is cooled in sections by warm water in a water tank. The water temperature of each section is controlled to be 60℃, 40℃ and room temperature in sequence along the direction of conductor travel. Finally, the insulated wire core 1 is obtained by pulling and winding.

[0097] Step 3: Prepare flame-retardant and rodent-resistant reinforced bundled insulated wires

[0098] Several insulated wire cores 1 are introduced into the bundled co-extrusion die in parallel. Tensile reinforcing fiber bundles 3 are led out through a constant tension wire feeding device, with the wire feeding tension controlled at 10N. The bundles are then accurately introduced into the center of the gap between two adjacent insulated wire cores 1 in the bundled co-extrusion die. Flame-retardant and rodent-proof polymer material particles are added to the second extruder, and the extrusion temperature is controlled at 155℃ to melt them. The melt enters the bundled co-extrusion die to complete the integrated extrusion molding, forming a flame-retardant and rodent-proof functional layer 2. The bundles are then pulled at a traction speed of 20m / min and cooled and shaped using a stepped water tank. The cooling water temperature is controlled to be 70℃, 50℃, 30℃ and room temperature along the direction of the conductor's travel. After winding, a flame-retardant and rodent-proof reinforced bundled insulated conductor is obtained.

[0099] Ethylene-vinyl acetate copolymer matrix, maleic anhydride-grafted polyolefin elastomer, aluminum hydroxide, and aminosilane-modified halloysite are melt-blended and extruded. The reaction between maleic anhydride and terminal amino groups strengthens interfacial compatibility. A lubricating, antioxidant, and light-stabilizing system is added to achieve uniform dispersion of flame-retardant fillers. The metal conductor is extruded and coated with cross-linked polyethylene and then cooled and shaped in stages to form an insulated wire core. Multiple wire cores and aramid fiber bundles are bundled and co-extruded together with a flame-retardant and rodent-proof polymer sheath through a bundled co-extrusion die. The bundled structure is then cooled and shaped in stages to form a bundled reinforcement structure.

[0100] Example 8

[0101] This embodiment provides a flame-retardant and rodent-proof reinforced bundled insulated wire, specifically including the following steps:

[0102] Step 1: Preparation of flame-retardant and rodent-proof polymer material particles

[0103] Ethylene bis-stearamide, zinc borate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], and light stabilizer 944 were mixed evenly in a mass ratio of 4.5:1.5:2.5:1.5 to obtain an auxiliary additive for later use.

[0104] Weigh out the following by weight: 65 parts of ethylene-vinyl acetate copolymer, 20 parts of maleic anhydride grafted polyolefin elastomer, 20 parts of aluminum hydroxide, 12.5 parts of flame-retardant and rodent-proof modified halloysite prepared in Example 5, and 2 parts of auxiliary additives. Add them to a high-speed mixer and mix at 85°C for 12 minutes. Transfer the mixture to a twin-screw extruder for melt blending, extrusion granulation, and obtain flame-retardant and rodent-proof polymer material particles.

[0105] The twin-screw extruder has a length-to-diameter ratio of 42:1 and a screw speed of 200 r / min. The processing temperatures of each section of the twin-screw extruder are controlled sequentially as follows: Zone 1 125℃, Zone 2 145℃, Zone 3 155℃, Zone 4 160℃, and Die head temperature 165℃.

[0106] Step 2: Preparing the Insulated Wire Core

[0107] The metal conductor 1-1 is led out through the wire feeding frame and passed through the first extruder. The extrusion temperature is controlled at 160℃ and the extrusion speed is 65m / min. An insulation layer 1-2 is extruded onto the outside of the metal conductor 1-1. Then, it is cooled in sections by warm water in a water tank. The water temperature of each section is controlled to be 65℃, 45℃ and room temperature in sequence along the direction of conductor travel. Finally, the insulated wire core 1 is obtained by pulling and winding.

[0108] Step 3: Prepare flame-retardant and rodent-resistant reinforced bundled insulated wires

[0109] Several insulated wire cores 1 are introduced into the bundled co-extrusion die in parallel. Tensile reinforcing fiber bundles 3 are led out through a constant tension wire feeding device, with the wire feeding tension controlled at 15N. The bundles are then accurately introduced into the center of the gap between two adjacent insulated wire cores 1 in the bundled co-extrusion die. Flame-retardant and rodent-proof polymer material particles are added to the second extruder, and the extrusion temperature is controlled at 165℃ to melt them. The melt enters the bundled co-extrusion die to complete the integrated extrusion molding, forming a flame-retardant and rodent-proof functional layer 2. The bundles are then pulled at a traction speed of 30m / min and cooled and shaped using a stepped water tank. The cooling water temperature is controlled to be 75℃, 55℃, 35℃ and room temperature along the direction of the conductor's travel. After winding, a flame-retardant and rodent-proof reinforced bundled insulated conductor is obtained.

[0110] Example 9

[0111] This embodiment provides a flame-retardant and rodent-proof reinforced bundled insulated wire, specifically including the following steps:

[0112] Step 1: Preparation of flame-retardant and rodent-proof polymer material particles

[0113] Ethylene bis-stearamide, zinc borate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and light stabilizer 944 were mixed evenly in a mass ratio of 5:2:3:2 to obtain an auxiliary additive for later use.

[0114] Weigh out the following by weight: 70 parts of ethylene-vinyl acetate copolymer, 25 parts of maleic anhydride grafted polyolefin elastomer, 25 parts of aluminum hydroxide, 15 parts of flame-retardant and rodent-proof modified halloysite prepared in Example 6, and 3 parts of auxiliary additives. Add them to a high-speed mixer and mix at 90°C for 15 minutes. Transfer the mixture to a twin-screw extruder for melt blending, extrusion granulation, and obtain flame-retardant and rodent-proof polymer material particles.

[0115] The twin-screw extruder has a length-to-diameter ratio of 48:1 and a screw speed of 250 r / min. The processing temperatures of each section of the twin-screw extruder are controlled sequentially as follows: Zone 1 130℃, Zone 2 150℃, Zone 3 160℃, Zone 4 165℃, and Die head temperature 170℃.

[0116] Step 2: Preparing the Insulated Wire Core

[0117] The metal conductor 1-1 is led out through the wire feeding frame and passed through the first extruder. The extrusion temperature is controlled at 170℃ and the extrusion speed is 80m / min. An insulation layer 1-2 is extruded onto the outside of the metal conductor 1-1. Then, it is cooled in sections by warm water in a water tank. The water temperature of each section is controlled to be 70℃, 50℃ and room temperature in sequence along the direction of conductor travel. Finally, the insulated wire core 1 is obtained by pulling and winding.

[0118] Step 3: Prepare flame-retardant and rodent-resistant reinforced bundled insulated wires

[0119] Several insulated wire cores 1 are introduced into the bundled co-extrusion die in parallel. Tensile reinforcing fiber bundles 3 are led out through a constant tension wire feeding device, with the wire feeding tension controlled at 20N. The bundles are then accurately introduced into the center of the gap between two adjacent insulated wire cores 1 in the bundled co-extrusion die. Flame-retardant and rodent-proof polymer material particles are added to the second extruder, and the extrusion temperature is controlled at 175℃ to melt them. The melt enters the bundled co-extrusion die to complete the integrated extrusion molding, forming a flame-retardant and rodent-proof functional layer 2. The bundles are then pulled at a traction speed of 40m / min and cooled and shaped using a stepped water tank. The cooling water temperature is controlled to be 80℃, 60℃, 40℃ and room temperature along the direction of wire travel. After winding, a flame-retardant and rodent-proof reinforced bundled insulated wire is obtained.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 9 is that, in the preparation of flame-retardant and rodent-proof modified halloysite, capsaicin-loaded halloysite was used in an equal amount to replace the coated modified halloysite.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Example 9 is that, in step one, when preparing flame-retardant and rodent-proof polymer material particles, halloysite nanotubes are used in an equal amount to replace the flame-retardant and rodent-proof modified halloysite.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 9 is that, in step three, when preparing the flame-retardant and rodent-proof reinforced bundled insulated wire, the addition of aramid fiber bundles is omitted.

[0126] Performance testing:

[0127] Sample preparation: The reinforced bundled insulated wires prepared in Examples 7-9 and Comparative Examples 1-3 were longitudinally cut open, the inner insulated core and aramid fiber bundles were stripped off, and the outer sheath was broken and then injection molded to obtain flame-retardant and rodent-proof functional layer samples.

[0128] Oxygen Index: The oxygen index of the flame-retardant and rodent-proof functional layer samples of reinforced bundled insulated wires prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to standard GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". The test environment was room temperature, and the oxygen index was used for characterization. The unit is % (%).

[0129] Tensile strength and elongation at break: The tensile strength and elongation at break of the flame-retardant and rodent-proof functional layer specimens of the reinforced bundled insulated conductors prepared in Examples 7-9 and Comparative Examples 1-3 were tested according to standard GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurements - Mechanical Properties Tests". The test environment was room temperature, and the results were characterized by tensile strength and elongation at break, respectively, in MPa and % (%).

[0130] Peak heat release rate: The peak heat release rate of the flame-retardant and rodent-proof functional layer samples of reinforced bundled insulated wires prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to standard GB / T 16172-2026 "Test Methods for Heat Release Rate and Smoke Production Rate of Building Materials". The test environment was room temperature, and the peak heat release rate was used for characterization. The unit is kW / m³. 2 ;

[0131] Carbon residue rate: The carbon residue rate of the flame-retardant and rodent-proof functional layer samples of reinforced bundled insulated wires prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to standard GB / T 9345.1-2008 "Determination of Ash Content in Plastics Part 1: General Method". The test environment was a nitrogen atmosphere, and the carbon residue rate was used for characterization, with the unit being % (%).

[0132] Rodent resistance performance: The rodent resistance performance of the reinforced bundled insulated wires prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 29199-2012 "Test Method for Rodent Resistance Performance of Optical Cable". The test environment was room temperature, and the rodent resistance index Rp was used to characterize the performance. Rp is dimensionless. The specific data are shown in Table 1 below.

[0133] Table 1 - Performance Test Data of Samples

[0134]

[0135] Comparative analysis of the data in Table 1 above shows that the oxygen index of the flame-retardant and rodent-proof functional layer sample of the reinforced bundled insulated wire prepared in this invention is 33.0%, the tensile strength is 16.2 MPa, the elongation at break is 375%, and the peak heat release rate is 230 kW·m. -2 Furthermore, the residual carbon rate is 25.5%, and the rodent bite resistance index of the reinforced bundled insulated wire is 5.8, all of which are better than the comparative example.

[0136] In Comparative Example 1, the unmodified halloysite had insufficient surface hydroxyl density and ineffective expansion of the lumen, resulting in weakened interfacial bonding with the matrix resin, deteriorated dispersibility, and significantly reduced mechanical properties. At the same time, the lack of melamine-cyanurate supramolecular coating and capsaicin loading greatly weakened the flame retardant and char-forming effects of the condensed phase, increased the peak heat release rate, reduced flame retardant performance, almost lost the rodent repellency effect, and reduced the rodent bite resistance index.

[0137] In Comparative Example 2, although terminal amino groups were introduced and capsaicin was loaded via silane coupling, the lack of a melamine-cyanurate supramolecular layer coating resulted in a lack of hydrogen bond self-assembly deposition interface enhancement between halloysite and the matrix, leading to lower mechanical properties compared to the Example. The absence of the melamine-cyanurate supramolecular layer resulted in a decrease in the flame-retardant barrier effect of the condensed phase, a reduction in char formation rate, and an increase in the peak heat release rate. Capsaicin, without coating protection, was prone to migration and loss, resulting in insufficient sustained-release effect, reduced rodent repellency, and a significant decrease in rodent bite resistance index.

[0138] In Comparative Example 3, the sheath formulation was the same as in the Example, and the flame-retardant and rodent-proof modified halloysite synergistic flame-retardant system was complete. Therefore, the peak values ​​of oxygen index, char residue, and heat release rate were similar to those in the Example, and the flame-retardant and rodent-proof performance did not change significantly. However, no aramid fiber bundles were introduced during the bundled co-extrusion molding, and the sheath layer lacked fiber skeleton support. The tensile strength and elongation at break were both lower than those in the Example, and the overall load-bearing and deformation resistance of the bundled structure was reduced.

[0139] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0140] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0141] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame-retardant and rodent-resistant reinforced bundled insulated wire, comprising a plurality of insulated cores (1), characterized in that, Several insulated wire cores are arranged in parallel, and several insulated wire cores are covered with a flame-retardant and rodent-proof functional layer (2). The insulated core (1) consists of a metal conductor (1-1) and an insulating layer (1-2) from the inside out. The metal conductor (1-1) is made of multiple strands of bare copper wire twisted together; The insulating layer (1-2) is made by extruding cross-linked polyethylene over the metal conductor; By weight, the flame-retardant and rodent-proof functional layer (2) comprises: 60-70 parts of ethylene-vinyl acetate copolymer, 15-25 parts of maleic anhydride-grafted polyolefin elastomer, 30-45 parts of halogen-free flame retardant, 10-15 parts of flame-retardant and rodent-proof modified halloysite, and 1-3 parts of auxiliary additives.

2. The flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 1, characterized in that, A tensile-strength fiber bundle (3) is provided between two adjacent insulated wire cores (1). The tensile-strength fiber bundle is covered by a flame-retardant and rodent-proof functional layer (2). The tensile-strength fiber bundle (3) is an aramid fiber bundle.

3. The flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 1, characterized in that, The preparation method of the flame-retardant and rodent-proof modified halloysite is as follows: coated modified halloysite, deionized water and ethanol are placed in a reaction vessel and stirred. Glacial acetic acid aqueous solution is added to adjust the pH to 4-5. 3-aminopropyltriethoxysilane is added. The reaction vessel is heated to 40-50℃ and kept at this temperature for 2-4 hours. The flame-retardant and rodent-proof modified halloysite is obtained after post-treatment.

4. The flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 3, characterized in that, The ratio of the amount of the coated modified halloysite, deionized water, ethanol and 3-aminopropyltriethoxysilane is 8-10g:15-20mL:120-140mL:1-2g, and the concentration of the glacial acetic acid aqueous solution is 3-5wt%.

5. A flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 3, characterized in that, The coated and modified halloysite is prepared using the following steps: B1. Place halloysite nanotubes and hydrochloric acid aqueous solution in a reaction vessel and stir. Heat the reaction vessel to 50-60℃ and keep it at the temperature for 2-4 hours. Post-treatment yields activated halloysite nanotubes. B2. Place n-nonanoic vanillamide and ethanol in a reaction vessel and stir. Add activated halloysite nanotubes and stir to disperse for 30-60 min. Vacuum impregnate and post-treatment to obtain capsaicin-loaded halloysite. B3. Place capsaicin-loaded halloysite and deionized water in a reaction vessel and stir. Heat the reaction vessel to 80-90℃, add cyanuric acid aqueous solution and melamine aqueous solution, heat the reaction vessel to 94-98℃, keep it at this temperature and stir for 2-4 hours, and then proceed with post-treatment to obtain coated modified halloysite.

6. A flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 5, characterized in that, In step B1, the ratio of halloysite nanotubes to hydrochloric acid aqueous solution is 1g:15-20mL, and the concentration of hydrochloric acid aqueous solution is 5-10wt%.

7. A flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 5, characterized in that, In step B2, the ratio of the amount of n-nonanoic acid vanillamide, ethanol and activated halloysite nanotubes is 2-5g:150-200mL:9-11g.

8. A flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 5, characterized in that, In step B3, the ratio of capsaicin-loaded halloysite, deionized water, cyanuric acid aqueous solution, and melamine aqueous solution is 10-12g:100-150mL:100-150mL:100-150mL. The cyanuric acid aqueous solution is obtained by mixing cyanuric acid and deionized water at a ratio of 4-6g:100-150mL. The melamine aqueous solution is obtained by mixing melamine and deionized water at a ratio of 4-6g:100-150mL. The temperature of both the cyanuric acid aqueous solution and the melamine aqueous solution is 94-96℃.

9. A flame-retardant and rodent-proof reinforced bundled insulated wire according to claim 5, characterized in that, The vacuum impregnation step includes: after stirring and dispersing, the suspension is transferred to a vacuum dryer, and a vacuum pump is connected to perform repeated vacuuming and vacuum breaking cycles. The vacuum degree is -0.08 to -0.1 MPa, the vacuuming time for each cycle is 10-15 min, the number of cycles is 3-5, and the system is allowed to stand for 5 min after each vacuum breaking. After the cycle is completed, the system is placed in a constant temperature water bath at 40-50℃ and kept warm and stirred for 12-24 h. The post-treatment yields capsaicin-loaded halloysite.

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