Silane naturally-crosslinked flame-retardant TPE cable material and preparation method thereof

Abstract

The invention belongs to the field of cable materials, and discloses a silane naturally-crosslinked flame-retardant TPE cable material and a preparation method thereof.The silane naturally-crosslinked flame-retardant TPE cable material comprises a conductor and an insulating layer wrapping the conductor; the insulating layer is prepared from the following components in parts by mass: 45 to 75 parts of TPE (Thermoplastic Elastomer) base material, 2 to 6 parts of composite silane cross-linking agent, 35 to 65 parts of novel composite flame retardant, 0.8 to 2.5 parts of composite antioxidant, 0.5 to 2 parts of lubricant, 3 to 8 parts of modified montmorillonite, 2 to 5 parts of sodium alginate-chitosan composite charring agent and 1 to 4 parts of gamma-aminopropyltriethoxysilane modified nano silicon dioxide; the invention aims to provide the silane natural crosslinking flame-retardant TPE cable material and the preparation method thereof, so as to solve the problems of low flame-retardant efficiency, poor mechanical property and insufficient crosslinking and flame-retardant synergy of the existing silane crosslinking flame-retardant TPE cable.

Description

Technical Field

[0001] This invention relates to the field of cable material technology, specifically to a silane naturally cross-linked flame-retardant TPE cable material and its preparation method. Background Technology

[0002] TPE materials, combining the elasticity of rubber with the processability of plastics, are widely used in cable insulation and sheathing layers. However, traditional TPE cables suffer from the problem of balancing flame retardancy and mechanical properties. Furthermore, in silane crosslinking systems, the addition of flame retardants can easily lead to a decrease in crosslinking efficiency and a deterioration in material dispersion, affecting the long-term stability of the cable.

[0003] In existing technologies, flame-retardant TPE cables mostly use a single halogen-free flame retardant such as magnesium hydroxide or aluminum hydroxide, or a simple compound flame retardant system. This results in low flame retardant efficiency and requires large amounts of additives, leading to a significant decrease in the material's mechanical properties. Furthermore, existing silane cross-linked TPE cables do not incorporate a synergistic system of modified clay and composite expandable flame retardants, making it impossible to simultaneously achieve high flame retardant ratings, excellent mechanical properties, and stable cross-linking effects. In addition, traditional cable materials lack optimized designs for flame retardant dispersion and cross-linking synergy, limiting the cable's application in high-temperature, high-requirement environments.

[0004] To address the aforementioned issues, this invention proposes a silane naturally cross-linked flame-retardant TPE cable material and its preparation method, which significantly improves the flame retardancy, mechanical properties, and thermal stability of the cable, filling a gap in existing technologies. Summary of the Invention

[0005] The present invention aims to provide a silane naturally cross-linked flame-retardant TPE cable material and its preparation method, so as to solve the problems of low flame-retardant efficiency, poor mechanical properties, and insufficient synergy between cross-linking and flame retardancy in existing silane cross-linked flame-retardant TPE cables.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The technical solution provided by this invention is: A silane-crosslinked flame-retardant TPE cable material includes a conductor and an insulation layer covering the conductor. The insulation layer is composed of the following components in parts by weight: 45-75 parts TPE base material, 2-6 parts composite silane crosslinking agent, 35-65 parts novel composite flame retardant, 0.8-2.5 parts composite antioxidant, 0.5-2 parts lubricant, 3-8 parts modified montmorillonite, 2-5 parts sodium alginate-chitosan composite charring agent, and 1-4 parts γ-aminopropyltriethoxysilane modified nano-silica. The TPE substrate is a blend of polycaprolactone and ethylene octene copolymer; The novel composite flame retardant is a compound of hydroxyapatite and nano-boron nitride, and the novel composite flame retardant also contains a composite intumescent flame retardant synergist of ammonium polyphosphate and pentaerythritol. The mass ratio of ammonium polyphosphate to pentaerythritol in the composite intumescent flame retardant synergist is 3:1-4:1. The composite silane crosslinking agent is a compound of methacryloyloxypropyltriethoxysilane and vinyltriethoxysilane; The modified montmorillonite is hexadecyltrimethylammonium bromide modified montmorillonite; The mass ratio of sodium alginate to chitosan in the sodium alginate-chitosan composite charcoal agent is 2:1-3:1. The particle size of the γ-aminopropyltriethoxysilane modified nano-silica is 30-100 nm.

[0007] Furthermore, the mass ratio of the polycaprolactone to the ethylene octene copolymer is 1:2-1:4; The mass ratio of hydroxyapatite to boron nitride nanoparticles is 5:1-8:1, and the particle size of boron nitride nanoparticles is 50-200 nm. In the novel composite flame retardant, the mass ratio of the compound of hydroxyapatite and nano boron nitride to the composite intumescent flame retardant synergist is 4:1-6:1.

[0008] Furthermore, the mass ratio of the methacryloyloxypropyltriethoxysilane to the vinyltriethoxysilane is 2:1-3:1; and the particle size of the modified montmorillonite is 20-80 μm.

[0009] Furthermore, the composite antioxidant is a compound of antioxidant 1076 and antioxidant DLTP, with a mass ratio of 1:1 to 2:1; the lubricant is a compound of erucamide and stearamide, with a mass ratio of 1:1 to 1:2.

[0010] Furthermore, the preparation method of the novel composite flame retardant is as follows: hydroxyapatite and nano boron nitride are weighed in proportion, stirred and mixed at a speed of 500-800 r / min for 15-20 min, then a composite intumescent flame retardant synergist is added, and stirring and mixing is continued for 20-30 min to obtain the novel composite flame retardant.

[0011] Furthermore, the insulating layer is also covered with a sheath layer, the composition of which is the same as that of the insulating layer, and the sheath layer also contains 1-3 parts by weight of polytetrafluoroethylene micro powder.

[0012] Furthermore, a shielding layer is provided between the conductor and the insulating layer. The shielding layer is a mixed braided layer of silver-plated copper wire and carbon fiber, with a mass ratio of silver-plated copper wire to carbon fiber of 10:1-15:1.

[0013] A method for preparing a silane naturally cross-linked flame-retardant TPE cable material includes the following steps: Preparation of sodium alginate-chitosan composite charcoal agent S1: Weigh sodium alginate and chitosan at a mass ratio of 2:1-3:1, dissolve them separately in deionized water and 1% acetic acid solution to prepare a sodium alginate solution with a mass fraction of 2%-3% and a chitosan solution with a mass fraction of 1%-2%. Slowly add the chitosan solution dropwise to the sodium alginate solution while stirring at a speed of 500-700 r / min. After the addition is complete, add calcium chloride at a mass fraction of 5%-8% as a crosslinking agent. Continue stirring and reacting at 30-40℃ for 1-2 h. Filter and wash until neutral, vacuum dry at 60-80℃ for 6-10 h, and pulverize to a particle size of 10-30 μm to obtain the sodium alginate-chitosan composite charcoal agent. S2 Preparation of γ-aminopropyltriethoxysilane modified nano-silica: Nano-silica is added to anhydrous ethanol to prepare a suspension with a mass fraction of 10%-15%, ultrasonically dispersed for 20-30 min, and γ-aminopropyltriethoxysilane with a mass of 8%-12% of nano-silica is added. The mixture is refluxed and stirred at 70-85℃ for 3-5 h, cooled and centrifuged, the precipitate is washed with anhydrous ethanol 3-4 times, dried at 100-110℃ for 4-6 h, and pulverized to a particle size of 30-100 nm to obtain γ-aminopropyltriethoxysilane modified nano-silica; S3 Preparation of composite intumescent flame retardant synergist: Weigh ammonium polyphosphate and pentaerythritol at a mass ratio of 3:1-4:1, put them into a high-speed mixer, mix for 15-25 minutes at 80-100℃ and 800-1200r / min, cool to room temperature and then pulverize to a particle size of 10-50μm to obtain the composite intumescent flame retardant synergist. Preparation of modified montmorillonite using S4: Add montmorillonite to deionized water to prepare a suspension with a mass fraction of 5%-8%, and ultrasonically disperse for 30-40 min. Then add 10%-15% of the mass of montmorillonite in cetyltrimethylammonium bromide, stir and react at 70-80℃ for 2-3 h, filter and wash until no bromide ions are detected in the filtrate, dry at 105-110℃ for 8-12 h, and pulverize to a particle size of 20-80 μm to obtain modified montmorillonite. S5 Preparation of novel composite flame retardant: Weigh hydroxyapatite and nano boron nitride at a mass ratio of 5:1-8:1, stir and mix at a speed of 500-800 r / min for 15-20 min, then add composite intumescent flame retardant synergist, and continue stirring and mixing at a mass ratio of hydroxyapatite and nano boron nitride compound to composite intumescent flame retardant synergist of 4:1-6:1 for 20-30 min to obtain novel composite flame retardant; Preparation of insulating granules by S6: Weigh 45-75 parts of TPE base material, 35-65 parts of the novel composite flame retardant prepared by S5, 0.8-2.5 parts of composite antioxidant, 0.5-2 parts of lubricant, 3-8 parts of modified montmorillonite prepared by S4, 2-5 parts of sodium alginate-chitosan composite charring agent prepared by S1, and 1-4 parts of γ-aminopropyltriethoxysilane modified nano-silica prepared by S2. Put them into a mixer and mix for 6-12 minutes at a rotor speed of 40-60 r / min and a temperature of 125-155℃ to obtain a premix. Add 2-6 parts of composite silane crosslinking agent and catalyst to the premix and continue mixing for 4-7 minutes at 115-135℃. Granulate the mixture using a twin-screw extruder to obtain insulating granules. S7 Preparation of cable core: If the cable contains a shielding layer, first mix silver-plated copper wire and carbon fiber in a mass ratio of 10:1-15:1 and weave them around the conductor to form a shielding layer. Then, wrap the insulating granules prepared in S6 around the shielding layer or conductor through an extruder at an extrusion temperature of 165-195℃ and a screw speed of 35-65r / min to obtain the cable core. S8 Preparation of cable blank: If the cable has a sheath layer, the sheath granules with 1-3 parts of polytetrafluoroethylene powder are coated on the outside of the insulation layer through an extruder at an extrusion temperature of 165-195℃ to obtain the cable blank; the preparation process of the sheath granules is the same as that of the insulation granules, except that polytetrafluoroethylene powder is added during the mixing process. S9 Natural Crosslinking: The cable core obtained from S7 or the cable blank obtained from S8 is placed in an environment with a temperature of 22-32℃ and a humidity of 45%-75% for natural crosslinking for 36-80 hours to obtain silane naturally crosslinked flame-retardant TPE cable material.

[0014] Furthermore, the catalyst described in S4 is a compound of zinc isooctanoate and dibutyltin dilaurate, with a mass ratio of 1:1 to 1:2, and the amount of catalyst added is 0.2 to 0.6 parts of the total mass of the insulating layer.

[0015] Furthermore, the barrel temperatures of the twin-screw extruder in S4 are 140-150℃, 155-165℃, 165-175℃, and 175-185℃ respectively; the barrel temperatures of the extruder in S5 are the same as those of the twin-screw extruder, and the barrel temperatures of the extruder in S6 are the same as those of the twin-screw extruder.

[0016] The beneficial effects of this technical solution are: (1) This solution uses hydroxyapatite and nano-boron nitride in combination, along with a composite intumescent flame retardant synergist composed of ammonium polyphosphate and pentaerythritol, to form a multi-element halogen-free flame retardant system. The high-temperature resistance of hydroxyapatite and the thermal conductivity of nano-boron nitride complement each other, which can inhibit heat conduction and accumulation during combustion; the composite intumescent flame retardant synergist can expand to form a dense char layer during combustion, physically blocking the flame and oxygen. The three work together to achieve excellent flame retardant effect without the need for large amounts of addition, avoiding the problem of substrate embrittlement caused by traditional single flame retardants, and ensuring the inherent elasticity of TPE substrate.

[0017] (2) The composite silane crosslinking agent is composed of methacryloyloxypropyltriethoxysilane and vinyltriethoxysilane, which can react efficiently with TPE substrate composed of polycaprolactone and ethylene octene copolymer, thus improving the uniformity of crosslinking. Hexadecyltrimethylammonium bromide modified montmorillonite improves its compatibility with organic substrates. Its layered structure can be uniformly dispersed in the system, which not only optimizes the dispersion effect of inorganic fillers, but also helps to promote the crosslinking reaction, avoiding the inhibition of crosslinking efficiency by the addition of flame retardants, and achieving synergistic effect of crosslinking and flame retardancy.

[0018] (3) Sodium alginate-chitosan composite charring agent can synergistically enhance the density and toughness of the char layer during combustion, further optimizing the flame retardant effect; γ-aminopropyltriethoxysilane modified nano-silica forms a stable interface bond with the substrate through surface modification, improving the overall mechanical properties and thermal stability. The reasonable ratio of composite antioxidant and compound lubricant not only inhibits the thermo-oxidative aging of the material, but also optimizes the processing fluidity, ensuring that each component is fully integrated in the system, so that the material can maintain its core performance while having long-term stability, avoiding the performance shortcomings caused by the functional limitations of a single component. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of a silane naturally cross-linked flame-retardant TPE cable material and its preparation method proposed in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The specific implementation process is as follows: Example 1: Please see Figure 1The present invention provides a technical solution: a silane naturally cross-linked flame-retardant TPE cable material and its preparation method, comprising the following components: 50 kg of TPE substrate (12.5 kg of polycaprolactone + 37.5 kg of ethylene octene copolymer, Engage8480), 3 kg of composite silane crosslinking agent (2 kg of methacryloxypropyltriethoxysilane + 1 kg of vinyltriethoxysilane), 45 kg of novel composite flame retardant (30 kg of hydroxyapatite, 5-10 μm particle size + 6 kg of nano boron nitride, 100 nm particle size + 9 kg of composite intumescent flame retardant synergist), 1.2 kg of composite antioxidant (0.8 kg of antioxidant 1076 + 0.4 kg of antioxidant DLTP), and 1 kg of lubricant (0.5 kg of erucamide + stearic acid). The following components were added: 0.5 kg of amide and 5 kg of modified montmorillonite (montmorillonite purity ≥ 98%); 3 kg of sodium alginate-chitosan composite charring agent (2 kg sodium alginate + 1 kg chitosan), and 2 kg of γ-aminopropyltriethoxysilane-modified nano-silica (particle size 50 nm); 6.75 kg of ammonium polyphosphate (degree of polymerization n ≥ 1000) + 2.25 kg of pentaerythritol in the composite intumescent flame retardant synergist; 2 kg of polytetrafluoroethylene micropowder (particle size 5 μm) added to the sheath layer; 1.2 kg of silver-plated copper wire (diameter 0.1 mm) and 0.1 kg of carbon fiber (diameter 7 μm) for the shielding layer; the conductor was a copper core with a cross-sectional area of ​​2.5 mm². 2 ; Preparation steps S1 Preparation of sodium alginate-chitosan composite charcoal agent: Weigh 2 kg of sodium alginate and 1 kg of chitosan, and dissolve them in deionized water and 1% acetic acid solution respectively to prepare a sodium alginate solution with a mass fraction of 2.5% and a chitosan solution with a mass fraction of 1.5%. Slowly add the chitosan solution dropwise to the sodium alginate solution at a stirring rate of 600 r / min. After the addition is complete, add 0.18 kg of calcium chloride (6% of the total mass of the two) as a crosslinking agent. Continue stirring and reacting at 35℃ for 1.5 h. Filter and wash until neutral, vacuum dry at 70℃ for 8 h, and pulverize to a particle size of 20 μm to obtain the sodium alginate-chitosan composite charcoal agent. S2 Preparation of γ-aminopropyltriethoxysilane modified nano-silica: 2 kg of nano-silica was added to anhydrous ethanol to prepare a suspension with a mass fraction of 12%, ultrasonically dispersed for 25 min, and 0.2 kg of γ-aminopropyltriethoxysilane (10% of the mass of nano-silica) was added. The mixture was refluxed and stirred at 75 °C for 4 h, cooled and centrifuged, the precipitate was washed 3 times with anhydrous ethanol, dried at 105 °C for 5 h, and pulverized to a particle size of 50 nm to obtain γ-aminopropyltriethoxysilane modified nano-silica; S3 Preparation of composite intumescent flame retardant synergist: Weigh 6.75 kg of ammonium polyphosphate and 2.25 kg of pentaerythritol, put them into a high-speed mixer, mix at 85°C and 1000 r / min for 20 min, cool and then pulverize to 30 μm to obtain composite intumescent flame retardant synergist; Preparation of modified montmorillonite (S4): Add 5 kg of montmorillonite to deionized water to prepare a 6% (w / w) suspension. Disperse the suspension by ultrasonication for 35 min. Then add 0.6 kg of cetyltrimethylammonium bromide (12% (w / w) of montmorillonite). Stir and react at 75 °C for 2.5 h. Filter and wash until no bromide ions are detected in the filtrate. Dry at 108 °C for 10 h and pulverize to 50 μm to obtain modified montmorillonite. S5 Preparation of a novel composite flame retardant: Weigh 30 kg of hydroxyapatite and 6 kg of nano boron nitride, stir and mix at 600 r / min for 18 min, add 9 kg of composite intumescent flame retardant synergist, and continue stirring and mixing for 25 min to obtain a novel composite flame retardant. Preparation of insulating granules in S6: Weigh 50 kg of TPE substrate, 45 kg of novel composite flame retardant, 1.2 kg of composite antioxidant, 1 kg of lubricant, 5 kg of modified montmorillonite, 3 kg of sodium alginate-chitosan composite charring agent prepared in S1, and 2 kg of γ-aminopropyltriethoxysilane modified nano-silica prepared in S2. Put them into a mixer and mix at 50 r / min rotor speed and 140℃ for 8 min to obtain a premix. Add 3 kg of composite silane crosslinking agent and 0.3 kg of catalyst (0.15 kg of zinc isooctanoate + 0.15 kg of dibutyltin dilaurate, both industrial grade), and continue mixing at 125℃ for 5 min. Granulate by twin-screw extruder with barrel temperatures of 145℃, 160℃, 170℃, and 180℃ respectively to obtain insulating granules. S7 Preparation of cable core: 1.2 kg of silver-plated copper wire and 0.1 kg of carbon fiber are mixed and woven around the conductor to form a shielding layer. Insulating granules are then coated around the shielding layer using an extruder at an extrusion temperature of 180℃ and a screw speed of 50 r / min to obtain the cable core. S8 Cable blank preparation: Sheath granules with 2kg of polytetrafluoroethylene powder added are coated on the outside of the insulation layer through an extruder at an extrusion temperature of 180℃ to obtain the cable blank; S9 Natural Crosslinking: The cable blank is placed in an environment of 25℃ and 60% humidity for 48 hours to crosslink, thus obtaining silane naturally crosslinked flame-retardant TPE cable material.

[0022] Test Project Test Results Vertical flammability rating V0 Tensile strength 12.5MPa Elongation at break 450% crosslinking degree 78% Thermal decomposition temperature 380℃ The vertical flammability rating of this embodiment reaches V0, demonstrating excellent flame retardant performance; the tensile strength reaches 12.5 MPa, and the elongation at break is 450%, reflecting good mechanical strength and flexibility; the degree of crosslinking is 78%, indicating that the natural crosslinking reaction of silane is sufficient and the internal structure of the material is stable; the thermal decomposition temperature is as high as 380℃, showing excellent thermal stability. All indicators can meet the usage requirements of high-demand application scenarios.

[0023] Example 2: Please see Figure 1 The present invention provides a technical solution: a silane naturally cross-linked flame-retardant TPE cable material and its preparation method, comprising the following components: 45 kg of TPE base material (11.25 kg of polycaprolactone + 33.75 kg of ethylene octene copolymer, Engage8480), 2 kg of composite silane crosslinking agent (1.33 kg of methacryloxypropyltriethoxysilane + 0.67 kg of vinyltriethoxysilane), 35 kg of novel composite flame retardant (25 kg of hydroxyapatite, 5-10 μm particle size + 5 kg of nano boron nitride, 100 nm particle size + 5 kg of composite intumescent flame retardant synergist), and 0.8 kg of composite antioxidant (0.4 kg of antioxidant 1076 + DLTP0 antioxidant). 4 kg of arsenic acid amide, 0.5 kg of lubricant (0.25 kg of erucic acid amide + 0.25 kg of stearic acid amide), 3 kg of modified montmorillonite (montmorillonite purity ≥ 98%), 2 kg of sodium alginate-chitosan composite charring agent (1.33 kg of sodium alginate + 0.67 kg of chitosan), and 1 kg of γ-aminopropyltriethoxysilane modified nano-silica (particle size 30 nm); the composite intumescent flame retardant synergist consists of 3.75 kg of ammonium polyphosphate (degree of polymerization n ≥ 1000) + 1.25 kg of pentaerythritol; no sheath layer; no shielding layer; the conductor is a copper core with a cross-sectional area of ​​2.5 mm². 2 ; Preparation steps S1 Preparation of sodium alginate-chitosan composite charcoal agent: Weigh 1.33 kg of sodium alginate and 0.67 kg of chitosan, and dissolve them in deionized water and 1% acetic acid solution respectively to prepare a 2% sodium alginate solution and a 1% chitosan solution. Slowly add the chitosan solution to the sodium alginate solution at a stirring rate of 500 r / min. After the addition is complete, add 0.1 kg of calcium chloride (5% of the total mass of the two) as a crosslinking agent. Continue stirring and reacting at 30°C for 1 h. Filter and wash until neutral, vacuum dry at 60°C for 10 h, and pulverize to a particle size of 10 μm to obtain the sodium alginate-chitosan composite charcoal agent. S2 Preparation of γ-aminopropyltriethoxysilane modified nano-silica: 1 kg of nano-silica was added to anhydrous ethanol to prepare a suspension with a mass fraction of 10%. The suspension was ultrasonically dispersed for 20 min. 0.08 kg of γ-aminopropyltriethoxysilane (8% of the mass of nano-silica) was added. The mixture was refluxed and stirred at 70 °C for 3 h. After cooling, the mixture was centrifuged. The precipitate was washed three times with anhydrous ethanol, dried at 100 °C for 6 h, and pulverized to a particle size of 30 nm to obtain γ-aminopropyltriethoxysilane modified nano-silica. S3 Preparation of composite intumescent flame retardant synergist: Weigh 3.75 kg of ammonium polyphosphate and 1.25 kg of pentaerythritol, put them into a high-speed mixer, mix at 80°C and 800 r / min for 25 min, cool and then pulverize to 50 μm to obtain composite intumescent flame retardant synergist; Preparation of modified montmorillonite by S4: Add 3 kg of montmorillonite to deionized water to prepare a 5% (w / w) suspension. Disperse the suspension by ultrasonication for 30 min. Then add 0.3 kg of hexadecyltrimethylammonium bromide (10% (w / w) of montmorillonite). Stir and react at 70 °C for 2 h. Filter and wash until no bromide ions are detected in the filtrate. Dry at 105 °C for 12 h. Pulverize to 20 μm to obtain modified montmorillonite. S5 Preparation of a novel composite flame retardant: Weigh 25 kg of hydroxyapatite and 5 kg of nano boron nitride, stir and mix at 500 r / min for 20 min, add 5 kg of composite intumescent flame retardant synergist, and continue stirring and mixing for 30 min to obtain a novel composite flame retardant. Preparation of insulating granules in S6: Weigh 45 kg of TPE substrate, 35 kg of novel composite flame retardant, 0.8 kg of composite antioxidant, 0.5 kg of lubricant, 3 kg of modified montmorillonite, 2 kg of sodium alginate-chitosan composite charring agent prepared in S1, and 1 kg of γ-aminopropyltriethoxysilane modified nano-silica prepared in S2. Put them into a mixer and mix at 125°C for 12 min with a rotor speed of 40 r / min to obtain a premix. Add 2 kg of composite silane crosslinking agent and 0.2 kg of catalyst (0.07 kg of zinc isooctanoate + 0.13 kg of dibutyltin dilaurate, both of which are industrial grade), and continue mixing at 115°C for 7 min. Granulate the mixture using a twin-screw extruder with barrel temperatures of 140°C, 155°C, 165°C, and 175°C to obtain insulating granules. S7 Preparation of cable core: Insulating granules are directly coated onto the conductor through an extruder at an extrusion temperature of 165℃ and a screw speed of 35r / min to obtain the cable core; S8 unsheathed layer preparation steps; S9 Natural Crosslinking: The cable core is placed in an environment of 22℃ and 45% humidity for 80 hours to crosslink, resulting in silane naturally crosslinked flame-retardant TPE cable material.

[0024] Test Project Test Results Vertical flammability rating V0 Tensile strength 11.2MPa Elongation at break 410% crosslinking degree 75% Thermal decomposition temperature 365℃ This embodiment achieves a V0 vertical combustion rating and meets flame retardant performance standards even with relatively low component addition; the tensile strength is 11.2 MPa and the elongation at break is 410%, and the mechanical properties meet the requirements of conventional use; the degree of crosslinking is 75%, ensuring the stability of the material structure; the thermal decomposition temperature is 365℃, and the thermal stability is good, demonstrating the performance advantages of this technical solution under low dosage configuration.

[0025] Example 3: Please see Figure 1 The present invention provides a technical solution: a silane naturally cross-linked flame-retardant TPE cable material and its preparation method, comprising the following components: 75 kg of TPE substrate (18.75 kg of polycaprolactone + 56.25 kg of ethylene octene copolymer, Engage8480), 6 kg of composite silane crosslinking agent (4.5 kg of methacryloxypropyltriethoxysilane + 1.5 kg of vinyltriethoxysilane), 65 kg of novel composite flame retardant (48 kg of hydroxyapatite, 5-10 μm particle size + 6 kg of nano boron nitride, 100 nm particle size + 11 kg of composite intumescent flame retardant synergist), 2.5 kg of composite antioxidant (1.67 kg of antioxidant 1076 + 0.83 kg of antioxidant DLTP), and 2 kg of lubricant (0.67 kg of erucamide). The composite intumescent flame retardant consists of: 1.33 kg of g+stearamide, 8 kg of modified montmorillonite (montmorillonite purity ≥98%), 5 kg of sodium alginate-chitosan composite charring agent (3 kg sodium alginate + 2 kg chitosan), and 4 kg of γ-aminopropyltriethoxysilane-modified nano-silica (particle size 100 nm); 8.8 kg of ammonium polyphosphate (degree of polymerization n ≥ 1000) + 2.2 kg of pentaerythritol in the composite intumescent flame retardant synergist; 3 kg of polytetrafluoroethylene micropowder (particle size 5 μm) added to the sheath layer; 1.5 kg of silver-plated copper wire (diameter 0.1 mm) and 0.1 kg of carbon fiber (diameter 7 μm) in the shielding layer; and a copper core with a cross-sectional area of ​​2.5 mm². 2 ; Preparation steps S1 Preparation of sodium alginate-chitosan composite charcoal agent: Weigh 3 kg of sodium alginate and 2 kg of chitosan, and dissolve them in deionized water and 1% acetic acid solution respectively to prepare a 3% sodium alginate solution and a 2% chitosan solution. Slowly add the chitosan solution to the sodium alginate solution at a stirring rate of 700 r / min. After the addition is complete, add 0.4 kg of calcium chloride (8% of the total mass of the two) as a crosslinking agent. Continue stirring and reacting at 40℃ for 2 h. Filter and wash until neutral, vacuum dry at 80℃ for 6 h, and pulverize to a particle size of 30 μm to obtain the sodium alginate-chitosan composite charcoal agent. S2 Preparation of γ-aminopropyltriethoxysilane modified nano-silica: 4 kg of nano-silica was added to anhydrous ethanol to prepare a suspension with a mass fraction of 15%, which was ultrasonically dispersed for 30 min. 0.48 kg of γ-aminopropyltriethoxysilane (12% of the mass of nano-silica) was added, and the mixture was refluxed and stirred at 85 °C for 5 h. After cooling, the mixture was centrifuged, the precipitate was washed 4 times with anhydrous ethanol, dried at 110 °C for 4 h, and pulverized to a particle size of 100 nm to obtain γ-aminopropyltriethoxysilane modified nano-silica. S3 Preparation of composite intumescent flame retardant synergist: Weigh 8.8 kg of ammonium polyphosphate and 2.2 kg of pentaerythritol, put them into a high-speed mixer, mix at 100℃ and 1200 r / min for 15 min, cool and then pulverize to 10 μm to obtain composite intumescent flame retardant synergist; Preparation of modified montmorillonite by S4: Add 8 kg of montmorillonite to deionized water to prepare a suspension with a mass fraction of 8%, and ultrasonically disperse for 40 min. Then add 1.2 kg of hexadecyltrimethylammonium bromide (15% of the mass of montmorillonite), stir and react at 80 °C for 3 h, filter and wash until no bromide ions are detected in the filtrate, dry at 110 °C for 8 h, and pulverize to 80 μm to obtain modified montmorillonite. S5 Preparation of a novel composite flame retardant: Weigh 48 kg of hydroxyapatite and 6 kg of nano boron nitride, stir and mix at 800 r / min for 15 min, add 11 kg of composite intumescent flame retardant synergist, continue stirring and mixing for 20 min to obtain a novel composite flame retardant. Preparation of insulating granules in S6: Weigh 75 kg of TPE substrate, 65 kg of novel composite flame retardant, 2.5 kg of composite antioxidant, 2 kg of lubricant, 8 kg of modified montmorillonite, 5 kg of sodium alginate-chitosan composite charring agent prepared in S1, and 4 kg of γ-aminopropyltriethoxysilane modified nano-silica prepared in S2. Put them into a mixer and mix at 60 r / min rotor speed and 155℃ for 6 min to obtain a premix. Add 6 kg of composite silane crosslinking agent and 0.6 kg of catalyst (0.2 kg of zinc isooctanoate + 0.4 kg of dibutyltin dilaurate, both industrial grade), and continue mixing at 135℃ for 4 min. Granulate by twin-screw extruder with barrel temperatures of 150℃, 165℃, 175℃, and 185℃ respectively to obtain insulating granules. S7 cable core preparation: 1.5 kg of silver-plated copper wire and 0.1 kg of carbon fiber are mixed and woven around the conductor to form a shielding layer. Insulating granules are then coated around the shielding layer using an extruder at an extrusion temperature of 195℃ and a screw speed of 65 r / min to obtain the cable core. S8 Preparation of cable blank: Sheath granules with 3kg of polytetrafluoroethylene powder added are coated on the outside of the insulation layer through an extruder at an extrusion temperature of 195℃ to obtain the cable blank; S9 Natural Crosslinking: The cable blank is placed in an environment of 32℃ and 75% humidity for 36 hours to crosslink, thus obtaining silane naturally crosslinked flame-retardant TPE cable material.

[0026] Test Project Test Results Vertical flammability rating V0 Tensile strength 13.1MPa Elongation at break 430% crosslinking degree 82% Thermal decomposition temperature 390℃ This embodiment uses a high amount of added components, maintaining a vertical flammability rating of V0, and exhibiting stable and reliable flame retardant performance; the tensile strength reaches 13.1 MPa, demonstrating the best mechanical strength performance; the elongation at break is 430%, also possessing good flexibility; the degree of crosslinking is 82%, the highest among all embodiments, indicating the most dense and stable crosslinked structure within the material; the thermal decomposition temperature is 390℃, demonstrating excellent thermal stability, making it suitable for high-end applications with stringent requirements for comprehensive material performance.

[0027] Comparative Example 1: Please see Figure 1 The present invention provides a comparative scheme: consistent with Example 1, except that the modified montmorillonite is removed; The preparation steps are the same as those in Example 1, except for the preparation steps of the unmodified montmorillonite. Test Project Test Results Vertical flammability rating V0 Tensile strength 8.2MPa Elongation at break 320% crosslinking degree 65% Thermal decomposition temperature 340℃ Although the vertical combustion rating of the comparative sample remained at V0 due to the absence of modified montmorillonite, other key properties showed a significant decline. The tensile strength was only 8.2 MPa, indicating insufficient mechanical strength; the elongation at break was 320%, indicating a decrease in flexibility; the degree of crosslinking was 65%, indicating reduced internal structural stability; and the thermal decomposition temperature was 340℃, indicating weakened thermal stability. This clearly reflects the role of modified montmorillonite in improving the overall performance of the material.

[0028] Comparative Example 2: Please see Figure 1 The present invention provides a comparative scheme: consistent with Example 1, the composite intumescent flame retardant synergist is removed from the novel composite flame retardant, and the total mass of hydroxyapatite and nano boron nitride is still 36 kg; The preparation steps are the same as in Example 1, except for the preparation steps of the composite intumescent flame retardant synergist. Test Project Test Results Vertical flammability rating V1 Tensile strength 10.5MPa Elongation at break 380% crosslinking degree 72% Thermal decomposition temperature 335℃ The comparative sample without the addition of the composite intumescent flame retardant synergist showed a decrease in vertical flammability rating from V0 to V1, indicating a significant deficiency in flame retardant performance. Tensile strength was 10.5 MPa, elongation at break was 380%, indicating a decline in mechanical properties. Crosslinking degree was 72%, suggesting a slight decrease in material structural stability. Thermal decomposition temperature was 335℃, indicating weakened thermal stability. This demonstrates that the synergistic effect of the composite intumescent flame retardant synergist with hydroxyapatite and nano-boron nitride is key to improving flame retardancy and overall performance.

[0029] Comparative Example 3: Please see Figure 1The present invention provides a comparative scheme: consistent with Example 1, except that the novel composite flame retardant is replaced with 45 kg of magnesium hydroxide (particle size 5-10 μm), the composite intumescent flame retardant synergist is removed, and the modified montmorillonite is replaced with 5 kg of unmodified montmorillonite; In the preparation steps: Preparation steps for S1-free composite intumescent flame retardant synergist; No S2-modified montmorillonite preparation step is required; 5 kg of unmodified montmorillonite is used directly. The preparation steps for the novel composite flame retardant without S3 are eliminated; 45 kg of magnesium hydroxide is directly used as the flame retardant. The rest is the same as in Example 1; Test Project Test Results Vertical flammability rating V1 Tensile strength 7.8MPa Elongation at break 290% crosslinking degree 60% Thermal decomposition temperature 320℃ The comparative example uses traditional flame retardant magnesium hydroxide and unmodified montmorillonite. The vertical flammability rating is only V1, indicating insufficient flame retardant performance; the tensile strength is 7.8 MPa, indicating poor mechanical strength; the elongation at break is 290%, indicating a significant decrease in flexibility; the degree of crosslinking is 60%, indicating insufficient internal structural stability of the material; and the thermal decomposition temperature is 320℃, indicating poor thermal stability. This fully demonstrates the significant performance improvement advantages of the novel composite flame retardant system and modified montmorillonite in this technical solution.

[0030] Comparative Example 4: Please see Figure 1 The present invention provides a comparative scheme: consistent with Example 1, except that the composite silane crosslinking agent is replaced with 3 kg of single vinyltriethoxysilane; The preparation steps are the same as in Example 1; Test Project Test Results Vertical flammability rating V0 Tensile strength 9.3MPa Elongation at break 350% crosslinking degree 68% Thermal decomposition temperature 350℃ The comparative example used a single silane crosslinking agent. Although the vertical combustion rating remained at V0, the tensile strength was 9.3 MPa and the elongation at break was 350%, which were significantly lower than those of Example 1. The degree of crosslinking was 68%, indicating that the crosslinking reaction was insufficient. The thermal decomposition temperature was 350°C, and the thermal stability decreased. This demonstrates the synergistic advantage of the composite silane crosslinking agent in improving crosslinking efficiency and the overall performance of the material.

[0031] Comparative Example 5: Please see Figure 1 The present invention provides a comparative scheme: Existing conventional silane cross-linked flame-retardant TPE cables consist of: 50 kg TPE substrate (50 kg ethylene octene copolymer, Engage 8480), 3 kg silane cross-linking agent (vinyltriethoxysilane), 45 kg flame retardant (aluminum hydroxide, particle size 5-10 μm), 1.2 kg antioxidant (antioxidant 1010), and 1 kg lubricant (zinc stearate); the conductor is a copper core with a cross-sectional area of ​​2.5 mm². 2 ; Preparation steps S1 lacks the preparation steps for composite intumescent flame retardant synergists; S2 lacks the preparation steps for modified montmorillonite; S3 lacks the preparation steps for novel composite flame retardants, directly using 45 kg of aluminum hydroxide as the flame retardant; S4 prepares insulating granules: weigh 50 kg of TPE substrate, 45 kg of aluminum hydroxide, 1.2 kg of antioxidant, and 1 kg of lubricant, put them into a mixer, mix at 50 r / min rotor speed and 140℃ for 8 min to obtain a premix; add 3 kg of silane crosslinking agent and 0.3 kg of catalyst (two-month laurel). (Dibutyltin oxide), continue mixing at 125℃ for 5 minutes, then granulate using a twin-screw extruder with barrel temperatures of 145℃, 160℃, 170℃, and 180℃ sequentially to obtain insulating granules; S5: Preparation of cable core: The insulating granules are directly extruded onto the conductor at an extrusion temperature of 180℃ and a screw speed of 50 r / min to obtain the cable core; S6: Preparation of sheathless layer; S7: Natural crosslinking: The cable core is placed in an environment of 25℃ and 60% humidity for crosslinking for 48 hours to obtain the product; Test Project Test Results Vertical flammability rating V2 Tensile strength 6.5MPa Elongation at break 250% crosslinking degree 55% Thermal decomposition temperature 300℃ The comparative example is a conventional product of the prior art, with a vertical flammability rating of only V2 and poor flame retardant performance; a tensile strength of 6.5 MPa, which is insufficient mechanical strength; an elongation at break of 250%, which is poor flexibility; a crosslinking degree of 55%, which is poor material structural stability; and a thermal decomposition temperature of 300℃, which is weak thermal stability. All indicators are far lower than those of the embodiment of this technical solution, which fully demonstrates the superior performance of the present invention.

[0032] Comparative Example 6: Please see Figure 1 The present invention provides a comparative scheme: the composition is the same as that of Example 1, except that the modified montmorillonite is removed; wherein 3 kg of sodium alginate-chitosan composite char-forming agent, 2 kg of γ-aminopropyltriethoxysilane modified nano silica, 1.2 kg of silver-plated copper wire for shielding layer and 0.1 kg of carbon fiber are included.

[0033] Preparation steps S1 Preparation of sodium alginate-chitosan composite charring agent: Same as Example 1; Preparation of γ-aminopropyltriethoxysilane-modified nano-silica by S2: Same as Example 1; S3 Preparation of Composite Intumescent Flame Retardant Synergist: Same as Example 1; Preparation steps of S4 unmodified montmorillonite; S5 Preparation of novel composite flame retardant: Same as Example 1; Preparation of insulating granules in S6: Weigh 50 kg of TPE substrate, 45 kg of novel composite flame retardant, 1.2 kg of composite antioxidant, 1 kg of lubricant, 3 kg of sodium alginate-chitosan composite charring agent prepared in S1, and 2 kg of γ-aminopropyltriethoxysilane modified nano-silica prepared in S2. Put them into a mixer and mix at 50 r / min rotor speed and 140℃ for 8 min to obtain a premix. Add 3 kg of composite silane crosslinking agent and 0.3 kg of catalyst (0.15 kg of zinc isooctanoate + 0.15 kg of dibutyltin dilaurate), and continue mixing at 125℃ for 5 min. Granulate by twin-screw extruder with barrel temperatures of 145℃, 160℃, 170℃, and 180℃ respectively to obtain insulating granules. S7 Preparation of cable core: 1.2 kg of silver-plated copper wire and 0.1 kg of carbon fiber are mixed and woven around the conductor to form a shielding layer. Insulating granules are then coated around the shielding layer using an extruder at an extrusion temperature of 180℃ and a screw speed of 50 r / min to obtain the cable core. S8 Preparation of cable blank: Same as in Example 1; S9 natural crosslinking: Same as Example 1.

[0034] Test Project Test Results Vertical flammability rating V0 Tensile strength 9.5MPa Elongation at break 350% crosslinking degree 70% Thermal decomposition temperature 360℃ The mechanical properties and crosslinking degree of this comparison were significantly reduced due to the lack of modified montmorillonite, which confirms the synergistic necessity of modified montmorillonite and the new components. At the same time, the performance of the new components was improved compared with the original comparative example 1, which reflects the positive role of the new components.

[0035] Comparative Example 7: Please see Figure 1 The present invention provides a comparative scheme: consistent with Example 1, except that the sodium alginate-chitosan composite char-forming agent is removed, while the types, amounts and process parameters of the other components remain unchanged; The preparation steps are completely identical to those in Example 1, except for step S1, which is the preparation step of sodium alginate-chitosan composite charring agent. In step S6, the composite charring agent is not added when preparing insulating granules. The remaining steps (S2-S5, S7-S9) are completely identical to those in Example 1. Test Project Test Results Vertical flammability rating V1 Tensile strength 10.8MPa Elongation at break 390% crosslinking degree 76% Thermal decomposition temperature 350℃ This comparative study, by omitting the sodium alginate-chitosan composite charring agent, clarified its core role: the composite charring agent synergistically enhances the density and toughness of the char layer during combustion, preventing char layer detachment and thus stabilizing the flame-retardant barrier effect; after its absence, the vertical burning rating decreased from V0 to V1, and the thermal decomposition temperature decreased from 380℃ to 350℃, confirming its synergistic effect in improving flame retardancy and thermal stability. Simultaneously, this charring agent can assist in enhancing the bonding force between the substrate and inorganic filler through interfacial interactions; its absence resulted in a significant decline in tensile strength and elongation at break, further demonstrating its important supplementary value in balancing flame retardancy and mechanical properties.

[0036] Through a systematic comparison of Examples 1-3 and Comparative Examples 1-7, it can be seen that Examples 1-3 cover different component dosage ranges and all achieve excellent performance with a vertical flammability rating of V0, tensile strength of not less than 11.2 MPa, elongation at break of not less than 410%, crosslinking degree of not less than 75%, and thermal decomposition temperature of not less than 365℃. Even though Example 2 uses a smaller amount of components (45 parts of TPE substrate, 35 parts of novel composite flame retardant, and 3 parts of modified montmorillonite), it can still meet the basic requirements of high-demand application scenarios. Furthermore, Example 3, by optimizing the component dosage (75 parts of TPE substrate, 65 parts of novel composite flame retardant, and 8 parts of modified montmorillonite), further increases the tensile strength to 13.1 MPa, the crosslinking degree to 82%, and the thermal decomposition temperature to 390℃, demonstrating the flexibility and superiority of this technical solution in performance adjustment. This proves that the proportion design of each component is scientific and reasonable and can adapt to application scenarios with different performance requirements. Compared to Comparative Example 1, which did not add modified montmorillonite, although the flame retardant rating remained at V0, the tensile strength decreased to 8.2 MPa, the elongation at break decreased to 320%, the degree of crosslinking decreased to 65%, and the thermal decomposition temperature decreased to 340℃, directly reflecting the key role of modified montmorillonite. After modification with hexadecyltrimethylammonium bromide, its surface oleophilicity was improved, and its compatibility with TPE substrate and other components was significantly optimized. The layered structure can not only improve the dispersion uniformity of the composite flame retardant and avoid agglomeration, but also catalyze the uniformity of the silane crosslinking reaction, thereby simultaneously enhancing the mechanical properties, crosslinking efficiency, and thermal stability of the material. This design is different from the conventional approach in the existing technology that does not modify the clay or does not synergistically design it with the flame retardant and crosslinking system.

[0037] Although Comparative Example 6 added sodium alginate-chitosan composite charring agent and γ-aminopropyltriethoxysilane modified nano-silica, it did not add modified montmorillonite. Its tensile strength was 9.5 MPa, elongation at break was 350%, crosslinking degree was 70%, and thermal decomposition temperature was 360℃, showing a significant improvement in performance compared to Comparative Example 1, but still far lower than Example 1. This result demonstrates the positive supplementary effect of the newly added composite charring agent and modified nano-silica on material performance, mitigating performance decline in the absence of modified montmorillonite. It also further confirms the synergistic necessity of modified montmorillonite and the newly added components—the newly added components alone cannot replace the core role of modified montmorillonite in improving dispersibility and catalyzing crosslinking reactions. The synergistic system of "modified clay + composite functional components" formed by the two is a key innovation of this technical solution.

[0038] In Comparative Example 2, after removing the composite intumescent flame retardant synergist (ammonium polyphosphate to pentaerythritol mass ratio 3:1-4:1), the vertical burning rating decreased from V0 to V1, the thermal decomposition temperature decreased to 335℃, and the mechanical properties and crosslinking degree also showed a significant decline, proving that the synergistic effect of the novel composite flame retardant system is indispensable. The high-temperature resistance of hydroxyapatite (particle size 5-10μm) and the thermal conductivity of nano boron nitride (particle size 100nm) complement each other, which can inhibit heat conduction during combustion. The composite intumescent flame retardant synergist composed of ammonium polyphosphate (degree of polymerization n≥1000) and pentaerythritol can expand to form a dense char layer during combustion, effectively blocking oxygen and flame spread. The multi-element flame retardant system formed by the combination of the three not only improves the flame retardant efficiency, but also avoids the material embrittlement problem caused by the large addition of a single flame retardant. Compared with the single halogen-free flame retardant or simple compound flame retardant system in the prior art, the flame retardant effect is better and the negative impact on mechanical properties is smaller.

[0039] Comparative Example 3, using the traditional flame retardant magnesium hydroxide (particle size 5-10 μm) and unmodified montmorillonite, showed a comprehensive deterioration in all properties: the vertical burning rating was only V1, the tensile strength dropped to 7.8 MPa, the elongation at break dropped to 290%, the degree of crosslinking dropped to 60%, and the thermal decomposition temperature dropped to 320%. This fully demonstrates that the novel composite flame retardant system combined with modified montmorillonite in this technical solution is significantly superior to the traditional material combination in terms of flame retardancy, mechanical properties, crosslinking efficiency, and thermal stability. It breaks through the limitation of existing technologies where traditional flame retardants and unmodified fillers cannot simultaneously achieve multiple properties.

[0040] Comparative Example 4 uses a single vinyltriethoxysilane as a crosslinking agent. Although the flame retardant rating remains at V0, the tensile strength drops to 9.3 MPa, the elongation at break drops to 350%, and the degree of crosslinking drops to 68%, demonstrating the synergistic advantages of the composite silane crosslinking agent. When methacryloyloxypropyltriethoxysilane is combined with vinyltriethoxysilane, it reacts more readily with the TPE substrate, modified montmorillonite, and the newly added composite components, improving the stability and uniformity of the crosslinking system, thereby improving the mechanical properties and thermal stability of the material. This is different from the single silane crosslinking agent design commonly used in existing technologies.

[0041] Compared to the conventional products of the prior art represented by Comparative Example 5 (TPE substrate is a single ethylene octene copolymer, flame retardant is aluminum hydroxide, and crosslinking agent is a single vinyltriethoxysilane), the advantages of this technical solution are more significant: the existing products have a vertical burning rating of only V2, tensile strength of 6.5 MPa, elongation at break of 250%, crosslinking degree of 55%, and thermal decomposition temperature of 300℃, while the embodiments of this technical solution have achieved a qualitative leap in flame retardancy rating, mechanical strength, flexibility, crosslinking stability, and thermal stability. Its core innovation lies in the construction of a multi-component synergistic system of "novel composite flame retardant system + modified montmorillonite + composite silane crosslinking agent + sodium alginate-chitosan composite charring agent + γ-aminopropyltriethoxysilane modified nano silica", rather than the simple addition of a single component. This not only solves the core defects of the existing technology, but also achieves multi-performance synergistic improvement on the basis of halogen-free environmental protection. It is suitable for fields such as construction, automobiles, and electronic equipment that have high requirements for the flame retardancy and reliability of cables, demonstrating significant technological progress and practical value.

[0042] The testing method is as follows: 1. Vertical Burning Rating: Fix the sample vertically, ignite it, and observe the extinguishing of the fire and whether the dripping material ignites the material below to determine the rating.

[0043] 2. Tensile strength and elongation at break: Prepare standard specimens, stretch them at a constant speed using a tensile testing machine, and record the strength and elongation at break.

[0044] 3. Degree of cross-linking: Soxhlet extraction was used with xylene as the extractant. After extracting the uncross-linked portion, the percentage of residual mass was calculated.

[0045] 4. Thermal decomposition temperature: Thermogravimetric analysis was performed under a nitrogen atmosphere, with the temperature at which the sample lost 5% of its weight was recorded.

[0046] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A silane naturally cross-linked flame-retardant TPE cable material, characterized in that, The product includes a conductor and an insulating layer covering the conductor. The insulating layer is composed of the following components in parts by weight: 45-75 parts TPE substrate, 2-6 parts composite silane crosslinking agent, 35-65 parts novel composite flame retardant, 0.8-2.5 parts composite antioxidant, 0.5-2 parts lubricant, 3-8 parts modified montmorillonite, 2-5 parts sodium alginate-chitosan composite charring agent, and 1-4 parts γ-aminopropyltriethoxysilane modified nano silica. The TPE substrate is a blend of polycaprolactone and ethylene octene copolymer; The novel composite flame retardant is a compound of hydroxyapatite and nano-boron nitride, and the novel composite flame retardant also contains a composite intumescent flame retardant synergist of ammonium polyphosphate and pentaerythritol. The mass ratio of ammonium polyphosphate to pentaerythritol in the composite intumescent flame retardant synergist is 3:1-4:

1. The composite silane crosslinking agent is a compound of methacryloyloxypropyltriethoxysilane and vinyltriethoxysilane; The modified montmorillonite is hexadecyltrimethylammonium bromide modified montmorillonite; The mass ratio of sodium alginate to chitosan in the sodium alginate-chitosan composite charcoal agent is 2:1-3:

1. The particle size of the γ-aminopropyltriethoxysilane modified nano-silica is 30-100 nm.

2. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, The mass ratio of the polycaprolactone to the ethylene octene copolymer is 1:2-1:4; The mass ratio of hydroxyapatite to nano-boron nitride is 5:1-8:1, and the particle size of nano-boron nitride is 50-200 nm. In the novel composite flame retardant, the mass ratio of the compound of hydroxyapatite and nano boron nitride to the composite intumescent flame retardant synergist is 4:1-6:

1.

3. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, The mass ratio of the methacryloyloxypropyltriethoxysilane to the vinyltriethoxysilane is 2:1-3:1; the particle size of the modified montmorillonite is 20-80 μm.

4. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, The composite antioxidant is a mixture of antioxidant 1076 and antioxidant DLTP, with a mass ratio of 1:1 to 2:1; the lubricant is a mixture of erucamide and stearamide, with a mass ratio of 1:1 to 1:

2.

5. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, The preparation method of the novel composite flame retardant is as follows: hydroxyapatite and nano boron nitride are weighed in proportion, stirred and mixed at a speed of 500-800 r / min for 15-20 min, then a composite intumescent flame retardant synergist is added, and stirring and mixing is continued for 20-30 min to obtain the novel composite flame retardant.

6. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, The insulating layer is further covered with a sheath layer, the composition of which is the same as that of the insulating layer, and the sheath layer also contains 1-3 parts by weight of polytetrafluoroethylene micro powder.

7. The silane naturally cross-linked flame-retardant TPE cable material according to claim 1, characterized in that, A shielding layer is provided between the conductor and the insulating layer. The shielding layer is a mixed braided layer of silver-plated copper wire and carbon fiber, and the mass ratio of silver-plated copper wire to carbon fiber is 10:1-15:

1.

8. A method for preparing silane naturally cross-linked flame-retardant TPE cable material as described in any one of claims 1-7, characterized in that, Includes the following steps: Preparation of sodium alginate-chitosan composite charcoal agent S1: Weigh sodium alginate and chitosan at a mass ratio of 2:1-3:1, dissolve them separately in deionized water and 1% acetic acid solution to prepare a sodium alginate solution with a mass fraction of 2%-3% and a chitosan solution with a mass fraction of 1%-2%. Slowly add the chitosan solution dropwise to the sodium alginate solution while stirring at a speed of 500-700 r / min. After the addition is complete, add calcium chloride at a mass fraction of 5%-8% as a crosslinking agent. Continue stirring and reacting at 30-40℃ for 1-2 h. Filter and wash until neutral, vacuum dry at 60-80℃ for 6-10 h, and pulverize to a particle size of 10-30 μm to obtain the sodium alginate-chitosan composite charcoal agent. S2 Preparation of γ-aminopropyltriethoxysilane modified nano-silica: Nano-silica is added to anhydrous ethanol to prepare a suspension with a mass fraction of 10%-15%, ultrasonically dispersed for 20-30 min, and γ-aminopropyltriethoxysilane with a mass of 8%-12% of nano-silica is added. The mixture is refluxed and stirred at 70-85℃ for 3-5 h, cooled and centrifuged, the precipitate is washed with anhydrous ethanol 3-4 times, dried at 100-110℃ for 4-6 h, and pulverized to a particle size of 30-100 nm to obtain γ-aminopropyltriethoxysilane modified nano-silica; S3 Preparation of composite intumescent flame retardant synergist: Weigh ammonium polyphosphate and pentaerythritol at a mass ratio of 3:1-4:1, put them into a high-speed mixer, mix for 15-25 minutes at 80-100℃ and 800-1200r / min, cool to room temperature and then pulverize to a particle size of 10-50μm to obtain the composite intumescent flame retardant synergist. Preparation of modified montmorillonite using S4: Add montmorillonite to deionized water to prepare a suspension with a mass fraction of 5%-8%, and ultrasonically disperse for 30-40 min. Then add 10%-15% of the mass of montmorillonite in cetyltrimethylammonium bromide, stir and react at 70-80℃ for 2-3 h, filter and wash until no bromide ions are detected in the filtrate, dry at 105-110℃ for 8-12 h, and pulverize to a particle size of 20-80 μm to obtain modified montmorillonite. S5 Preparation of novel composite flame retardant: Weigh hydroxyapatite and nano boron nitride at a mass ratio of 5:1-8:1, stir and mix at a speed of 500-800 r / min for 15-20 min, then add composite intumescent flame retardant synergist, and continue stirring and mixing at a mass ratio of hydroxyapatite and nano boron nitride compound to composite intumescent flame retardant synergist of 4:1-6:1 for 20-30 min to obtain novel composite flame retardant; Preparation of insulating granules by S6: Weigh 45-75 parts of TPE base material, 35-65 parts of the novel composite flame retardant prepared by S5, 0.8-2.5 parts of composite antioxidant, 0.5-2 parts of lubricant, 3-8 parts of modified montmorillonite prepared by S4, 2-5 parts of sodium alginate-chitosan composite charring agent prepared by S1, and 1-4 parts of γ-aminopropyltriethoxysilane modified nano-silica prepared by S2. Put them into a mixer and mix for 6-12 minutes at a rotor speed of 40-60 r / min and a temperature of 125-155℃ to obtain a premix. Add 2-6 parts of composite silane crosslinking agent and catalyst to the premix and continue mixing for 4-7 minutes at 115-135℃. Granulate the mixture using a twin-screw extruder to obtain insulating granules. S7 Preparation of cable core: If the cable contains a shielding layer, first mix silver-plated copper wire and carbon fiber in a mass ratio of 10:1-15:1 and weave them around the conductor to form a shielding layer. Then, wrap the insulating granules prepared in S6 around the shielding layer or conductor through an extruder at an extrusion temperature of 165-195℃ and a screw speed of 35-65r / min to obtain the cable core. S8 Preparation of cable blank: If the cable has a sheath layer, the sheath granules with 1-3 parts of polytetrafluoroethylene powder are coated on the outside of the insulation layer through an extruder at an extrusion temperature of 165-195℃ to obtain the cable blank; the preparation process of the sheath granules is the same as that of the insulation granules, except that polytetrafluoroethylene powder is added during the mixing process. S9 Natural Crosslinking: The cable core obtained from S7 or the cable blank obtained from S8 is placed in an environment with a temperature of 22-32℃ and a humidity of 45%-75% for natural crosslinking for 36-80 hours to obtain silane naturally crosslinked flame-retardant TPE cable material.

9. The preparation method according to claim 8, characterized in that, The catalyst described in S4 is a compound of zinc isooctanoate and dibutyltin dilaurate, with a mass ratio of 1:1 to 1:

2. The amount of catalyst added is 0.2 to 0.6 parts of the total mass of the insulating layer.

10. The preparation method according to claim 8, characterized in that, The barrel temperatures of the twin-screw extruder in S4 are 140-150℃, 155-165℃, 165-175℃, and 175-185℃, respectively; the barrel temperatures of the extruder in S5 and S6 are the same as those of the twin-screw extruder.

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