Low-smoke halogen-free environment-friendly insulated cable material and preparation method thereof

Abstract

The invention discloses a low-smoke halogen-free environment-friendly insulated cable material and a preparation method thereof, belongs to the technical field of insulated cable materials, and is used for solving the technical problem that the insulating property and flame retardant property of an insulated cable material in the prior art need to be further improved. The material comprises the following raw materials in parts by weight: 80-100 parts of cross-linked polypropylene and 21-28 parts of an auxiliary additive, graphene and boron nitride are activated, double-bond structures are modified on the surfaces of the graphene and the boron nitride, the graphene and the boron nitride are mixed to obtain a composite filler, the composite filler is modified by a ball-milling modifier in the ball-milling process, the modified composite filler and a polypropylene material are mixed, melted and extruded, and the composite filler is prepared. And carrying out electron radiation to obtain crosslinked polypropylene, and carrying out mixing, melting and extrusion on the crosslinked polypropylene and auxiliary materials to obtain the low-smoke wear-resistant insulated cable material.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating cable materials, and particularly relates to an environmentally friendly low-smoke and halogen-free insulating cable material and a preparation method thereof. Background Art

[0002] The research and development of environmentally friendly low-smoke and halogen-free insulating cable materials has gone through multiple stages. Starting from traditional materials such as PVC at the beginning, although it has good insulation performance, it will release toxic gases in case of fire, posing safety hazards. With the improvement of environmental protection requirements, cross-linked polyethylene gradually replaces PVC, providing better electrical performance and high-temperature resistance, entering the low-smoke and halogen-free era. Environmentally friendly cable materials not only require good insulation, but also need to avoid the release of toxic smoke. During this period, researchers used halogen-free flame retardants that do not release harmful gases while achieving flame retardancy. Low-smoke and halogen-free materials can effectively reduce toxic smoke in case of fire and are widely used in places with high safety requirements such as subways, buildings, and aviation. With the progress of technology, the electrical insulation performance and flame retardancy of low-smoke and halogen-free cable materials have been continuously improved to meet the dual requirements of environmental protection and safety in modern society.

[0003] For example, the prior art CN103351506B discloses an insulating cable material and a preparation method thereof, which are made of the following raw materials in parts by weight: 34-37 of high-density polyethylene, 12-15 of EVA, 3-4 of octadecyl alcohol polyoxyethylene ether, 8-10 of poly-1-butene, 24-27 of linear low-density polyethylene, 1-2 of silicon carbide powder, 2-3 of dibutyltin dilaurate, 2-3 of zinc oxide, 35-39 of bauxite, 23-26 of bentonite, 1-2 of accelerator DTDM, 2-3 of vinyltris(β-methoxyethoxy)silane, 4-6 of ethyl acrylate, 15-20 of carbon black N339, 23-26 of N660 carbon black, 1-2 of antioxidant 1035, and 6-8 of modified diatomite. The provided cable material has excellent temperature resistance, flexibility, and oil resistance.

[0004] However, the above-mentioned invention adds auxiliary materials to high-density polyethylene and obtains an insulating cable material through melt blending and extrusion. However, the cross-linking degree of high-density polyvinyl chloride as the matrix material is too high, and its compatibility with auxiliary materials is significantly reduced during the melt extrusion blending process, resulting in the need for further improvement in the insulation performance, wear resistance, and flame retardancy of the cable material prepared by this invention. Summary of the Invention

[0005] The purpose of the present invention is to provide an environmentally friendly low-smoke and halogen-free insulating cable material and a preparation method thereof, which are used to solve the technical problem that the insulation performance and flame retardancy of insulating cable materials in the prior art need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solutions: An environmentally friendly low-smoke and halogen-free insulating cable compound, comprising the following raw materials in parts by weight: 80-100 parts of crosslinked polypropylene and 21-28 parts of auxiliary additives;

[0007] The auxiliary additives are obtained by mixing a plasticizer, a stabilizer, a lubricant and an antioxidant in a dosage ratio of 12-15 g: 3-4 g: 3-4 g: 3-5 g;

[0008] The preparation method of the crosslinked polypropylene comprises the following steps:

[0009] A1. Add polypropylene and a modified filler into a twin-screw extruder, melt and extrude to granulate, obtaining modified polypropylene;

[0010] A2. Place the modified polypropylene in an irradiation tank, after electron irradiation, perform post-treatment to obtain crosslinked polypropylene.

[0011] Reaction principle for preparing crosslinked polypropylene: Free electrons move at high speed under the drive of an electric field, and collide frequently with the lattice vibration in the activated graphene component. This kind of collision converts part of the electron kinetic energy into phonon vibration energy, forming Joule heat, which excites the polypropylene molecular chains to generate active sites. The double bond structure on the surface of the modified filler reacts directly with the active sites of polypropylene under irradiation, forming chemical connections between molecular chains. This crosslinked structure enhances the overall stability of the material by fixing the spatial arrangement of molecular chains and constructing a three-dimensional network, and finally crosslinked polypropylene is prepared.

[0012] Further, the plasticizer is tributyl citrate; the stabilizer is one or both of butylated hydroxytoluene and triphenyl phosphite; the lubricant is one or more of calcium stearate and montan wax; the antioxidant is one or both of pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(tert-butylhydroxyphenyl) acrylate.

[0013] Further, in step A1, the dosage ratio of polypropylene to the modified filler is 80 - 100 g: 20 - 30 g. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet towards the discharge outlet are 180 °C, 185 °C, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 100 - 120 rpm, and the pressure is 80 - 120 bar. The electron radiation operation is as follows: After filling the irradiation tank with argon and sealing it, place the irradiation tank in the cobalt source room for room-temperature irradiation, with an absorbed dose of 60 - 80 kGy, where the irradiation dose rate is 3.2 - 3.4 kGy / h. The post-treatment is as follows: After the electron radiation operation is completed, take out the material from the irradiation tank and transfer it to an incubator at a temperature of 70 - 90 °C. After vacuum treatment for 2 - 4 h, raise the temperature of the incubator to 130 - 150 °C, keep it warm and static for 1 - 2 h, then take out the material and naturally cool it to room temperature to obtain cross-linked polypropylene.

[0014] Further, the preparation method of the modified filler includes the following steps:

[0015] B1. Mix the composite filler and the ball-milling modifier, then add them to the corundum mortar. After mixing evenly, a composite material is obtained.

[0016] B2. Transfer the composite material to a planetary ball mill, ball-mill for 3 - 4 h, and then perform post-treatment to obtain the modified filler.

[0017] The reaction principle for preparing the modified filler is as follows: During the ball-milling process, the active functional groups in the ball-milling modifier and the active functional groups in the composite filler cross-link, so that during the dispersion and grinding of the composite filler, the ball-milling modifier is evenly dispersed on the surface of the composite material, and finally the modified filler is prepared.

[0018] Further, in step B1, the dosage ratio of the composite filler, the ball-milling modifier, and the corundum mortar is 1 - 2 g: 3 - 4 g: 20 - 25 g. In step B2, place 20 - 24 5-mm zirconia grinding balls and 15 - 18 3-mm zirconia grinding balls in the planetary ball mill. The ball-milling speed is 700 - 800 r / min, and the grinding direction is reversed every 0.5 h. The post-treatment includes: After ball-milling is completed, collect the milled material, transfer the milled material to hot water at 80 - 90 °C, stir for 5 - 8 min, then filter the solution to collect the filter cake. Wash the filter cake 3 - 5 times with anhydrous ethanol and deionized water, and then transfer the precipitate to a vacuum drying oven at 60 °C for vacuum drying to constant weight to obtain the modified filler.

[0019] Further, the preparation method of the composite filler includes the following steps:

[0020] C1. Add graphene and 98.0 wt% sulfuric acid into a reaction kettle at a temperature of 0 - 5 °C and stir. After keeping the temperature and stirring for 10 - 15 min, add sodium chlorate into the reaction kettle. Keep the temperature of the reaction kettle at 0 - 5 °C and react for 2 - 4 h. Then use saturated sodium hydroxide solution to adjust the pH of the reaction system to 7, and obtain activated graphene through post-treatment;

[0021] C2. Add boron nitride and 30 - 40 wt% hydrogen peroxide aqueous solution into a high-pressure reaction kettle. Raise the temperature of the high-pressure reaction kettle to 120 - 150 °C. After keeping the temperature for 6 - 8 h, obtain activated boron nitride through post-treatment;

[0022] C3. Add activated graphene, activated boron nitride, absolute ethanol and deionized water into a reaction kettle. Use saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8 - 9. Then raise the temperature of the reaction kettle to 40 - 60 °C and add a modifier solution into the reaction kettle. Keep the temperature and react for 40 - 60 min, and obtain a composite filler through post-treatment.

[0023] The reaction principle for preparing the composite filler is as follows: After the surfaces of graphene and boron nitride are activated, active functional groups are formed on the surfaces. Under alkaline conditions, the siloxane groups on methacryloxypropyltriethoxysilane hydrolyze to form silanol structures, thereby forming a cross-linked structure with activated graphene and activated boron nitride, and finally obtaining the composite filler.

[0024] Further, in step C1, the dosage ratio of multi-layer graphene, 98.0 wt% sulfuric acid and sodium chlorate is 5 - 8 g: 30 - 40 g: 3 - 5 g. The post-treatment includes: after the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, then filter the solution to collect the filter cake. Wash the filter cake 3 - 5 times with absolute ethanol and deionized water, and then transfer the precipitate to a vacuum drying oven at 60 °C and vacuum dry to constant weight to obtain activated graphene;

[0025] Further, in step C2, the dosage ratio of boron nitride and 30 - 40 wt% hydrogen peroxide aqueous solution is 2 - 3 g: 10 - 15 mL. The post-treatment includes: after the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, then filter the solution to collect the filter cake. Wash the filter cake 3 - 5 times with absolute ethanol and deionized water, and then transfer the precipitate to a vacuum drying oven at 60 °C and vacuum dry to constant weight to obtain activated boron nitride;

[0026] Further, in step C3, the dosage ratio of activated graphene, activated boron nitride, absolute ethanol, deionized water and modifier solution is 1-2 g: 3-4 g: 20-24 mL: 12-15 mL: 12-16 mL. Among them, the modifier solution consists of γ-methacryloxypropyltriethoxysilane and absolute ethanol in a dosage ratio of 1-2 g: 12-16 mL. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, filter the solution to collect the filter cake, wash the filter cake 3-5 times with absolute ethanol and deionized water, then transfer the precipitate to a vacuum drying oven at 60 °C and vacuum dry it to constant weight to obtain the composite filler.

[0027] Further, the preparation method of the ball milling modifier includes the following steps: Add N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and N,N-dimethylformamide into a reaction kettle at a temperature of 0-5 °C, keep stirring until all the reactants are dissolved, then add 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarbonic anhydride into the reaction kettle in three portions. After the addition is completed, the temperature of the reaction kettle is steadily raised to 30-50 °C and kept reacting for 2-4 h, and then the ball milling modifier is obtained through post-treatment.

[0028] The reaction equation for preparing the ball milling modifier is:

[0029]

[0030] In the formula: "*" represents the active connection site of the organic chain segment.

[0031] The reaction principle for preparing the ball milling modifier is: the amino group on N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and the anhydride group on 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarbonic anhydride undergo a ring-opening reaction under heating conditions, and finally the ball milling modifier with a long-chain structure is prepared.

[0032] Further, the dosage ratio of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine, N,N-dimethylformamide and 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarbonic anhydride is 4.0-4.4 g: 30-36 mL: 3.6-4.0 g. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80-100 °C, and perform vacuum distillation until no liquid is produced to obtain the ball milling modifier.

[0033] The present invention also provides a method for preparing a low-smoke and halogen-free environmentally friendly insulating cable material: adding cross-linked polypropylene, a plasticizer, a stabilizer, a lubricant and an antioxidant into a twin-screw extruder, melting and extruding, and obtaining the insulating cable material after natural curing.

[0034] Furthermore, the temperatures of the eight temperature zones of the twin-screw extruder from the feed port towards the discharge port are 180°C, 185°C, 185°C, 200°C, 200°C, 210°C, 210°C, 220°C in sequence. The main machine speed of the twin-screw extruder is 100 - 120 rpm, and the pressure is 80 - 120 bar.

[0035] The present invention has the following beneficial effects:

[0036] 1. In the present invention, surface treatment is used to change the chemical structure of graphene, blocking the internal current conduction path. Boron nitride has natural insulation, and its layered structure forms a physical barrier layer in the material to block the passage of current. The combination of the two not only retains the insulation advantage of boron nitride but also eliminates the conductive risk of graphene through modification. Secondly, through a mechanical mixing process, the treated graphene and boron nitride are uniformly dispersed in the resin matrix to avoid the aggregation of conductive particles to form a path, and the tight combination of the surface modifier and the resin further eliminates micro-gaps to prevent local leakage. Finally, the charge isolation of the cross-linked structure, and the electron irradiation process enables the filler and the resin molecules to form a stable three-dimensional cross-linked network. The cross-linking points fix the positions of the fillers, maintaining a uniform dispersion state. The chemical bonds generated by cross-linking can capture free charges, reducing charge migration. Through the triple synergistic mechanism of suppressing conductivity through material modification, avoiding structural defects through uniform dispersion, and isolating charges through the cross-linked network, the high insulation performance of the material is ultimately achieved.

[0037] 2. After surface treatment of graphene and boron nitride in the present invention, the two are closely combined to form a stable combined structure. The high-strength characteristic of graphene is directly transmitted to the polypropylene matrix through chemical bonds, while the layered characteristic of boron nitride reduces surface loss through microscopic sliding during friction. The ball milling process evenly disperses the two to form support points throughout the material, preventing excessive deformation by fixing the molecular structure, thereby improving the overall tensile strength. Secondly, the electron irradiation process enables the modified filler and the polypropylene molecules to form a tightly connected network structure. This cross-linked network, on the one hand, restricts the movement of molecular chains, directly improving the material's ability to resist tensile fracture; on the other hand, it disperses external pressure through evenly distributed support points, reducing local wear during friction and avoiding rapid surface loss. Finally, the filler after surface treatment forms a firm bond with the polypropylene matrix. When an external force acts, stress is evenly transmitted through chemical bonds, preventing cracking at the bonding surface. At the same time, the cooperation of the cross-linked network and the dispersed filler enables the material to consume energy through multiple ways such as molecular chain constraint, support point deformation, and interface sliding during the stretching or friction process, ultimately improving the tensile strength and wear resistance of the material.

[0038] 3. The present invention also conducts surface activation treatment on graphene and boron nitride, and uses a silane coupling agent to form a stable composite structure between the two. The high thermal conductivity of graphene enables the heat generated by combustion to rapidly spread, delaying the sharp rise in local temperature. Boron nitride decomposes at high temperatures to form a dense oxide layer, blocking the transfer of oxygen and heat. At the same time, a triazine-based modifier containing phosphorus and nitrogen elements is introduced. During combustion, it not only releases inert gases to dilute the concentration of combustibles but also catalyzes the formation of a continuous carbonized layer in polypropylene. Through an electron irradiation process, double bonds on the surface of the modified filler react with the polypropylene molecular chains to construct a three-dimensional crosslinked network. This structure increases the bonding strength between molecular chains, enhances the thermal stability of the material, and promotes the rapid formation of a complete carbonized protective layer during the combustion process, blocking the penetration of heat and combustible gases. The ball milling process realizes the uniform dispersion of the filler in the resin matrix, and the spatial barrier effect of the modifier prevents the agglomeration of nanomaterials, ensuring that the flame retardant components cover comprehensively at the microscale. The physical barrier of the composite filler reduces the combustion intensity, the chemical flame retardant mechanism of the triazine derivative inhibits gas-phase reactions, the crosslinked structure stabilizes the morphology of the carbonized layer, and the uniform dispersion ensures the overall stability of the system. Finally, during the combustion process, the double effects of improving the flame retardancy efficiency and reducing the smoke generation amount are achieved simultaneously, meeting the performance requirements of environmentally friendly cable materials. Detailed implementation manners

[0039] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Embodiment 1

[0041] This embodiment provides a preparation method for a composite filler used in the preparation of a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0042] Step ①, prepare activated graphene

[0043] Weigh: 50.0 g of graphene and 300.0 g of 98.0 wt% sulfuric acid are added to a reaction kettle at a temperature of 0 °C and stirred. After maintaining the stirring for 10 min, 30.0 g of sodium chlorate is added to the reaction kettle. After the temperature of the reaction kettle is maintained at 0 °C for 2 h, the pH of the reaction system is adjusted to 7 using saturated sodium hydroxide solution. After the reaction is completed, after the temperature of the reaction kettle is lowered to room temperature, the solution is filtered to collect the filter cake. After washing the filter cake 3 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at a temperature of 60 °C and vacuum dried to constant weight to obtain activated graphene.

[0044] Step ②, prepare activated boron nitride

[0045] Weigh: 20.0 g of boron nitride and 100.0 mL of 30 wt% hydrogen peroxide aqueous solution are added to a high-pressure reactor. The temperature of the high-pressure reactor is raised to 120 °C. After holding the temperature for 6 h and the reaction is completed, after the temperature of the reactor is lowered to room temperature, the solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at 60 °C and vacuum dried to a constant weight to obtain activated boron nitride.

[0046] Step ③, Preparation of composite filler

[0047] Weigh: 10.0 g of 3-(Trimethoxysilyl)propyl methacrylate and 120.0 mL of absolute ethanol are mixed to obtain a modification solution;

[0048] Weigh: 10.0 g of activated graphene, 30.0 g of activated boron nitride, 200.0 mL of absolute ethanol and 120.0 mL of deionized water are added to the reactor. After adjusting the pH of the reaction system to 8 with saturated sodium hydroxide aqueous solution, the temperature of the reactor is raised to 40 °C and 120.0 mL of the modification solution is added to the reactor. After holding the temperature for 40 min and the reaction is completed, after the temperature of the reactor is lowered to room temperature, the solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at 60 °C and vacuum dried to a constant weight to obtain the composite filler.

[0049] Example 2

[0050] This example provides a preparation method of a composite filler for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0051] Step ①, Preparation of activated graphene

[0052] Weigh: 80.0 g of graphene and 40.0 g of 98.0 wt% sulfuric acid are added to a reactor at 5 °C and stirred. After holding the temperature for 15 min, 50.0 g of sodium chlorate is added to the reactor. After the temperature of the reactor is maintained at 5 °C for 4 h, the pH of the reaction system is adjusted to 7 with saturated sodium hydroxide solution. After the reaction is completed, after the temperature of the reactor is lowered to room temperature, the solution is filtered by suction to collect the filter cake. After washing the filter cake 5 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at 60 °C and vacuum dried to a constant weight to obtain activated graphene.

[0053] Step ②, Preparation of activated boron nitride

[0054] Weigh: 30.0 g of boron nitride and 150.0 mL of 40 wt% hydrogen peroxide aqueous solution were added to a high-pressure reactor. The temperature of the high-pressure reactor was raised to 150 °C. After holding the temperature for 8 h and the reaction was completed, after the temperature of the reactor was lowered to room temperature, the solution was filtered by suction to collect the filter cake. After washing the filter cake 5 times with absolute ethanol and deionized water, the precipitate was transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain activated boron nitride.

[0055] Step ③, Preparation of composite filler

[0056] Weigh: 20.0 g of methacryloxypropyltriethoxysilane and 160.0 mL of absolute ethanol were mixed to obtain a modification solution;

[0057] Weigh: 20.0 g of activated graphene, 40.0 g of activated boron nitride, 240.0 mL of absolute ethanol and 150.0 mL of deionized water were added to a reactor. After adjusting the pH of the reaction system to 9 with saturated sodium hydroxide aqueous solution, the temperature of the reactor was raised to 60 °C and 160.0 mL of the modification solution was added to the reactor. After holding the reaction for 60 min and the reaction was completed, after the temperature of the reactor was lowered to room temperature, the solution was filtered by suction to collect the filter cake. After washing the filter cake 5 times with absolute ethanol and deionized water, the precipitate was transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain the composite filler.

[0058] Example 3

[0059] This example provides a preparation method of a composite filler for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0060] Step ①, Preparation of activated graphene

[0061] Weigh: 60.0 g of graphene and 360.0 g of 98.0 wt% sulfuric acid were added to a reactor at 3 °C and stirred. After holding the stirring for 12 min, 40.0 g of sodium chlorate was added to the reactor. After the temperature of the reactor was maintained at 3 °C for 3 h, the pH of the reaction system was adjusted to 7 with saturated sodium hydroxide solution. After the reaction was completed, after the temperature of the reactor was lowered to room temperature, the solution was filtered by suction to collect the filter cake. After washing the filter cake 4 times with absolute ethanol and deionized water, the precipitate was transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain activated graphene.

[0062] Step ②, Preparation of activated boron nitride

[0063] Weigh: 24.0 g of boron nitride and 120.0 mL of 36 wt% hydrogen peroxide aqueous solution are added to a high-pressure reactor. The temperature of the high-pressure reactor is raised to 135 °C. After maintaining the temperature for 7 h and the reaction is completed, after the temperature of the reactor drops to room temperature, the solution is filtered by suction to collect the filter cake. After washing the filter cake 4 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain activated boron nitride.

[0064] Step ③, prepare the composite filler

[0065] Weigh: 16.0 g of 3-(trimethoxysilyl)propyl methacrylate and 150.0 mL of absolute ethanol are mixed to obtain a modification solution;

[0066] Weigh: 16.0 g of activated graphene, 36.0 g of activated boron nitride, 210.0 mL of absolute ethanol and 150.0 mL of deionized water are added to the reactor. After adjusting the pH of the reaction system to 9 with saturated sodium hydroxide aqueous solution, the temperature of the reactor is raised to 50 °C and 150.0 mL of the modification solution is added to the reactor. After maintaining the reaction for 50 min and the reaction is completed, after the temperature of the reactor drops to room temperature, the solution is filtered by suction to collect the filter cake. After washing the filter cake 4 times with absolute ethanol and deionized water, the precipitate is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain the composite filler.

[0067] Example 4

[0068] This example provides a preparation method of a ball milling modifier for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0069] Weigh: 40.0 g of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and 300.0 mL of N,N-dimethylformamide are added to a reactor at 0 °C. After maintaining stirring until all the reactants are dissolved, 36.0 g of 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride is added to the reactor in three portions. After the addition is completed, the temperature of the reactor is steadily raised to 30 °C and the reaction is maintained for 2 h. After the reaction is completed, after the temperature of the reactor drops to room temperature, the reaction solution is added to a rotary evaporator with a water bath temperature of 80 °C and distilled under reduced pressure until no liquid is collected to obtain the ball milling modifier.

[0070] Example 5

[0071] This example provides a preparation method of a ball milling modifier for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0072] Weigh: 44.0 g of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and 360.0 mL of N,N-dimethylformamide and add them to a reaction kettle at 5 °C. After keeping warm and stirring until all the reactants are dissolved, add 40.0 g of 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride to the reaction kettle in three portions. After the addition is completed, the temperature of the reaction kettle is steadily raised to 50 °C, and the reaction is carried out under insulation for 4 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, then add the reaction solution to a rotary evaporator with a water bath temperature of 100 °C, and carry out vacuum distillation until no liquid is drawn out to obtain a ball milling modifier.

[0073] Example 6

[0074] This example provides a preparation method of a ball milling modifier for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0075] Weigh: 42.0 g of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and 320.0 mL of N,N-dimethylformamide and add them to a reaction kettle at 3 °C. After keeping warm and stirring until all the reactants are dissolved, add 38.0 g of 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride to the reaction kettle in three portions. After the addition is completed, the temperature of the reaction kettle is steadily raised to 40 °C, and the reaction is carried out under insulation for 3 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, then add the reaction solution to a rotary evaporator with a water bath temperature of 90 °C, and carry out vacuum distillation until no liquid is drawn out to obtain a ball milling modifier.

[0076] Example 7

[0077] This example provides a preparation method of a modified filler for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0078] Step Ⅰ. Prepare a composite material

[0079] Weigh: Mix 10.0 g of the composite filler prepared in Example 1 and 30.0 g of the ball milling modifier prepared in Example 4, and then add them to 200.0 g of corundum mortar. After mixing evenly, a composite material is obtained.

[0080] Step Ⅱ. Prepare a modified filler

[0081] Weigh: Transfer 30.0 g of the composite material into a planetary ball mill. Place 20 zirconia grinding balls with a diameter of 5 mm and 15 zirconia grinding balls with a diameter of 3 mm in the planetary ball mill. The ball milling speed is 700 r / min, and the grinding direction is reversed every 0.5 h. After fully ball milling for 3 h, after the ball milling is completed, collect the milled material. Transfer the milled material into hot water at 80 °C, stir for 5 min, then filter the solution to collect the filter cake. Wash the filter cake 3 times with absolute ethanol and deionized water, and then transfer the precipitate into a vacuum drying oven at 60 °C and vacuum dry it to constant weight to obtain the modified filler.

[0082] Example 8

[0083] This example provides a preparation method of a modified filler for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0084] Step Ⅰ. Prepare the composite material

[0085] Weigh: Mix 20.0 g of the composite filler prepared in Example 2 and 40.0 g of the ball milling modifier prepared in Example 5, and then add them to 250.0 g of corundum mortar. After mixing evenly, obtain the composite material.

[0086] Step Ⅱ. Prepare the modified filler

[0087] Weigh: Transfer 40.0 g of the composite material into a planetary ball mill. Place 24 zirconia grinding balls with a diameter of 5 mm and 18 zirconia grinding balls with a diameter of 3 mm in the planetary ball mill. The ball milling speed is 800 r / min, and the grinding direction is reversed every 0.5 h. After fully ball milling for 4 h, after the ball milling is completed, collect the milled material. Transfer the milled material into hot water at 90 °C, stir for 8 min, then filter the solution to collect the filter cake. Wash the filter cake 5 times with absolute ethanol and deionized water, and then transfer the precipitate into a vacuum drying oven at 60 °C and vacuum dry it to constant weight to obtain the modified filler.

[0088] Example 9

[0089] This example provides a preparation method of a modified filler for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0090] Step Ⅰ. Prepare the composite material

[0091] Weigh: Mix 16.0 g of the composite filler prepared in Example 3 and 36.0 g of the ball milling modifier prepared in Example 6, and then add them to 250.0 g of corundum mortar. After mixing evenly, obtain the composite material.

[0092] Step Ⅱ. Prepare the modified filler

[0093] Weigh: Transfer 36.0 g of the composite material into a planetary ball mill. Place 21 zirconia grinding balls with a diameter of 5 mm and 16 zirconia grinding balls with a diameter of 3 mm in the planetary ball mill. The ball milling speed is 720 r / min, and the grinding direction is reversed every 0.5 h. After fully ball milling for 4 h, after the ball milling is completed, collect the milled material, transfer the milled material into hot water at 90 °C, stir for 7 min, filter the solution to collect the filter cake, wash the filter cake 4 times with absolute ethanol and deionized water, then transfer the precipitate into a vacuum drying oven at 60 °C and vacuum dry it to constant weight to obtain the modified filler.

[0094] Example 10

[0095] This example provides a preparation method of cross-linked polypropylene for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0096] Step (i), prepare modified polypropylene

[0097] Weigh: Add 80.0 g of polypropylene and 20.0 g of the modified filler into a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port towards the discharge port are 180 °C, 185 °C, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 100 rpm, the pressure is 80 bar, and melt extrusion and pelletization are carried out to obtain modified polypropylene.

[0098] Step (ii), prepare cross-linked polypropylene

[0099] Weigh: Place 80.0 g of the modified polypropylene in an irradiation tank, fill the irradiation tank with argon and seal it, place the irradiation tank in a cobalt source room for room-temperature irradiation, absorb 60 kGy of irradiation at an irradiation dose rate of 3.2 kGy / h. After the electron radiation operation is completed, take out the material from the irradiation tank and transfer it to a constant-temperature oven at 70 °C. After vacuum treatment for 2 h, raise the temperature of the constant-temperature oven to 130 °C, keep it warm and static for 1 h, then take out the material and naturally cool it to room temperature to obtain cross-linked polypropylene.

[0100] Example 11

[0101] This example provides a preparation method of cross-linked polypropylene for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0102] Step (i), prepare modified polypropylene

[0103] Weigh: 100.0 g of polypropylene and 30.0 g of modified filler are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet towards the discharge outlet are 180 °C, 185, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 120 rpm, the pressure is 120 bar, and melt extrusion granulation is carried out to obtain modified polypropylene.

[0104] Step (ii), preparing crosslinked polypropylene

[0105] Weigh: 100.0 g of modified polypropylene is placed in an irradiation tank. After filling the irradiation tank with argon and sealing it, the irradiation tank is placed in a cobalt source room for room-temperature irradiation, absorbing 80 kGy of irradiation at an irradiation dose rate of 3.4 kGy / h. After the electron radiation operation is completed, the material is taken out of the irradiation tank and transferred to an incubator at 90 °C. After vacuum treatment for 4 h, the temperature of the incubator is raised to 150 °C. After heat preservation and static standing for 2 h, the material is taken out and naturally cooled to room temperature to obtain crosslinked polypropylene.

[0106] Example 12

[0107] This example provides a preparation method of crosslinked polypropylene for preparing a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0108] Step (i), preparing modified polypropylene

[0109] Weigh: 90.0 g of polypropylene and 25.0 g of modified filler are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet towards the discharge outlet are 180 °C, 185, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 100 rpm, the pressure is 80 bar, and melt extrusion granulation is carried out to obtain modified polypropylene.

[0110] Step (ii), preparing crosslinked polypropylene

[0111] Weigh: 90.0 g of modified polypropylene is placed in an irradiation tank. After filling the irradiation tank with argon and sealing it, the irradiation tank is placed in a cobalt source room for room-temperature irradiation, absorbing 72 kGy of irradiation at an irradiation dose rate of 3.3 kGy / h. After the electron radiation operation is completed, the material is taken out of the irradiation tank and transferred to an incubator at 80 °C. After vacuum treatment for 3 h, the temperature of the incubator is raised to 150 °C. After heat preservation and static standing for 2 h, the material is taken out and naturally cooled to room temperature to obtain crosslinked polypropylene.

[0112] Example 13

[0113] This example provides a preparation method of a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0114] Weigh: 80 parts of crosslinked polypropylene, 12 parts of tributyl citrate, 3 parts of triphenyl phosphite, 3 parts of calcium stearate, and 3 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet are 180 °C, 185, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 100 rpm, the pressure is 80 bar, and after melt extrusion and natural curing, an insulating cable material is obtained.

[0115] Example 14

[0116] This example provides a preparation method of a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0117] Weigh: 100 parts of crosslinked polypropylene, 15 parts of tributyl citrate, 4 parts of triphenyl phosphite, 4 parts of calcium stearate, and 5 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet are 180 °C, 185, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 120 rpm, the pressure is 120 bar, and after melt extrusion and natural curing, an insulating cable material is obtained.

[0118] Example 15

[0119] This example provides a preparation method of a low-smoke and halogen-free environmentally friendly insulating cable material, including the following steps:

[0120] Weigh: 96 parts of crosslinked polypropylene, 12 parts of tributyl citrate, 3 parts of triphenyl phosphite, 4 parts of calcium stearate, and 4 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet are 180 °C, 185, 185 °C, 200 °C, 200 °C, 210 °C, 210 °C, and 220 °C in sequence. The main machine speed of the twin-screw extruder is 100 rpm, the pressure is 100 bar, and after melt extrusion and natural curing, an insulating cable material is obtained.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Example 15 is that during the preparation of the crosslinked polypropylene used, during the preparation of the modified polypropylene used, in the composite filler used for preparing the modified filler, the use of activated graphene is cancelled.

[0123] Comparative Example 2

[0124] The difference between this comparative example and Example 15 is that in the process of preparing the crosslinked polypropylene used, the composite filler used for preparing the modified filler used in the process of preparing the modified polypropylene cancels step ③ in the preparation process.

[0125] Comparative Example 3

[0126] The difference between this comparative example and Example 15 is that in the process of preparing the crosslinked polypropylene used, step ㈡ is cancelled.

[0127] Data analysis:

[0128] Refer to the standard GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Resistive properties (DC method) - Volume resistance and volume resistivity" to test the volume resistivity of the insulating cable compounds prepared in Examples 13-15 and Comparative Examples 1-3;

[0129] Refer to the standard GB / T 2408-2021 "Plastics - Determination of burning behaviour - Horizontal and vertical methods" to test the vertical burning grade of the insulating cable compounds prepared in Examples 13-15 and Comparative Examples 1-3;

[0130] Refer to the standard GB / T 9867-2008 "Rubber, vulcanized or thermoplastic - Determination of abrasion resistance (rotary roller abrader method)" to test the volume abrasion loss of the insulating cable compounds prepared in Examples 13-15 and Comparative Examples 1-3;

[0131] Refer to the standard GB / T 32129-2015 "Halogen-free low-smoke flame retardant cable compounds for wire and cable" to test the tensile strength and smoke density of the insulating cable compounds prepared in Examples 13-15 and Comparative Examples 1-3. The specific data are shown in Table 1.

[0132] Table 1 - Performance test data table of each sample

[0133]

[0134] Performance test:

[0135] By comparing and analyzing the data in Table 1, it can be found that the volume resistivity of the insulating cable compound prepared by the present invention is 1.7×10 16 Ω·m, the vertical burning grade is V-0, the volume abrasion loss is 21.8 mm 3 ³, the tensile strength is 70.1 MPa, and the smoke density is 107 in the flaming state and 53 in the non-flaming state. All the data are better than the comparison;

[0136] It is noted that in the present invention, the chemical structure of graphene is changed through surface treatment to block the internal current conduction path. Boron nitride has natural insulation properties, and its layered structure forms a physical barrier layer in the material to block the passage of current. The combination of the two not only retains the insulation advantages of boron nitride but also eliminates the conductive risk of graphene through modification. Secondly, through a mechanical mixing process, the treated graphene and boron nitride are uniformly dispersed in the resin matrix to avoid the aggregation of conductive particles to form a conductive path. The tight combination of the surface modifier and the resin further eliminates micro-gaps to prevent local leakage. Finally, due to the charge isolation of the cross-linked structure, the electron irradiation process enables the filler and the resin molecules to form a stable three-dimensional cross-linked network. The cross-linking points fix the positions of the fillers and maintain a uniform dispersion state. The chemical bonds generated by cross-linking can capture free charges and reduce charge migration. Through the triple synergistic mechanism of suppressing conductivity through material modification, avoiding structural defects through uniform dispersion, and isolating charges through the cross-linked network, the high insulation performance of the material is ultimately achieved;

[0137] It is noted that in the present invention, surface activation treatment is carried out on graphene and boron nitride, and a stable composite structure is formed between the two using a silane coupling agent. The high thermal conductivity of graphene enables the heat generated by combustion to spread rapidly, delaying the sharp rise in local temperature. Boron nitride decomposes at high temperatures to form a dense oxide layer, blocking the transfer of oxygen and heat. At the same time, a triazine-based modifier containing phosphorus and nitrogen elements is introduced. During combustion, it not only releases inert gases to dilute the concentration of combustibles but also catalyzes the formation of a continuous carbonized layer in polypropylene. Through the electron irradiation process, the double bonds on the surface of the modified filler react with the polypropylene molecular chains to construct a three-dimensional cross-linked network. This structure increases the bonding strength between molecular chains, improves the thermal stability of the material, and promotes the rapid formation of a complete carbonized protective layer during the combustion process, blocking the penetration of heat and combustible gases. The ball milling process achieves the uniform dispersion of the filler in the resin matrix, and the steric hindrance effect of the modifier prevents the aggregation of nanomaterials, ensuring that the flame retardant components cover the entire system at the microscale. The physical barrier of the composite filler reduces the combustion intensity, the chemical flame retardant mechanism of the triazine derivative inhibits the gas-phase reaction, the cross-linked structure stabilizes the morphology of the carbonized layer, and the uniform dispersion ensures the overall stability of the system. Finally, during the combustion process, the dual effects of improving the flame retardant efficiency and reducing the smoke generation amount are simultaneously achieved, meeting the performance requirements of environmentally friendly cable materials;

[0138] It is noted that in the present invention, graphene and boron nitride are surface-treated to closely combine them to form a stable combined structure. The high-strength property of graphene is directly transmitted to the polypropylene matrix through chemical bonds, while the layered property of boron nitride reduces surface loss through microscopic sliding during friction. The ball-milling process evenly disperses the two to form support points throughout the material, preventing excessive deformation by fixing the molecular structure, thereby enhancing the overall tensile strength. Secondly, the electron irradiation process forms a tightly connected network structure between the modified filler and the polypropylene molecules. This crosslinked network, on the one hand, restricts the movement of molecular chains, directly improving the material's ability to resist tensile fracture; on the other hand, it disperses external pressure through evenly distributed support points, reducing local wear during friction and avoiding rapid surface loss. Finally, the surface-treated filler and the polypropylene matrix form a firm bond. When an external force acts, stress is evenly transmitted through chemical bonds, preventing cracking at the bonding surface. At the same time, the cooperation of the crosslinked network and the dispersed filler enables the material to consume energy through multiple means such as molecular chain constraint, support point deformation, and interface sliding during the stretching or friction process, ultimately enhancing the tensile strength and wear resistance of the material.

[0139] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation manners described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An environmentally friendly low-smoke and halogen-free insulating cable compound, characterized in that, The raw material composition includes the following parts by weight: 80-100 parts of cross-linked polypropylene and 21-28 parts of auxiliary additives; The auxiliary additives are obtained by mixing a plasticizer, a stabilizer, a lubricant and an antioxidant in a dosage ratio of 12-15g:3-4g:3-4g:3-5g; The preparation method of the cross-linked polypropylene includes the following steps: A1. Add polypropylene and a modified filler into a twin-screw extruder, melt and extrude to granulate to obtain modified polypropylene; A2. Place the modified polypropylene in an irradiation tank, after electron irradiation, perform post-treatment to obtain cross-linked polypropylene.

2. The environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 1, wherein In step A1, the dosage ratio of polypropylene to the modified filler is 80-100g:20-30g; the electron irradiation operation is: after filling the irradiation tank with argon and sealing it, place the irradiation tank in a cobalt source chamber for normal temperature irradiation, with an absorbed dose of 60-80kGy irradiation, wherein the irradiation dose rate is 3.2-3.4kGy / h, and the post-treatment is: after the electron irradiation operation is completed, take out the material from the irradiation tank and transfer it to an incubator at a temperature of 70-90°C, perform vacuum treatment for 2-4h, then raise the temperature of the incubator to 130-150°C, keep it warm and static for 1-2h, take out the material, and naturally cool it to room temperature to obtain cross-linked polypropylene.

3. An environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 1, characterized in that The preparation method of the modified filler includes the following steps: B1. Mix the composite filler and the ball milling modifier and add them into the corundum mortar, and after mixing evenly, obtain a composite material; B2. Transfer the composite material to a planetary ball mill, ball mill for 3-4h, and perform post-treatment to obtain the modified filler.

4. An environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 3, characterized in that, In step B1, the dosage ratio of the composite filler, the ball milling modifier and the corundum mortar is 1-2g:3-4g:20-25g; in step B2, place 20-24 5mm zirconia grinding balls and 15-18 3mm zirconia grinding balls in the planetary ball mill, the ball milling speed is 700-800r / min, and reverse the grinding direction every 0.5h.

5. An environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 3, characterized in that, The preparation method of the composite filler includes the following steps: C1. Add graphene and 98.0wt% sulfuric acid into a reaction kettle at a temperature of 0-5°C and stir, after keeping warm and stirring for 10-15min, add sodium chlorate into the reaction kettle, keep the temperature of the reaction kettle at 0-5°C and react for 2-4h, then use saturated sodium hydroxide solution to adjust the pH of the reaction system to 7, and perform post-treatment to obtain activated graphene; C2. Add boron nitride and 30-40wt% hydrogen peroxide aqueous solution into a high-pressure reaction kettle, raise the temperature of the high-pressure reaction kettle to 120-150°C, keep warm for 6-8h, and perform post-treatment to obtain activated boron nitride; C3. Add the activated graphene, the activated boron nitride, anhydrous ethanol and deionized water into the reaction kettle, use saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8-9, then raise the temperature of the reaction kettle to 40-60°C and add a modification solution into the reaction kettle, keep warm and react for 40-60min, and perform post-treatment to obtain the composite filler.

6. The environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 5, characterized in that, In step C1, the dosage ratio of multi-layer graphene, 98.0 wt% sulfuric acid and sodium chlorate is 5-8 g: 30-40 g: 3-5 g; in step C2, the dosage ratio of boron nitride and 30-40 wt% hydrogen peroxide aqueous solution is 2-3 g: 10-15 mL; in step C3, the dosage ratio of activated graphene, activated boron nitride, absolute ethanol, deionized water and modifier is 1-2 g: 3-4 g: 20-24 mL: 12-15 mL: 12-16 mL, wherein the modifier consists of γ-methacryloxypropyltriethoxysilane and absolute ethanol in a dosage ratio of 1-2 g: 12-16 mL.

7. An environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 3, characterized in that, The preparation method of the ball milling modifier comprises the following steps: adding N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine and N,N-dimethylformamide into a reaction kettle at a temperature of 0-5 °C, stirring while keeping warm until all the reactants are dissolved, then adding 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride into the reaction kettle in three portions. After the addition, the temperature of the reaction kettle is steadily raised to 30-50 °C, and the reaction is carried out while keeping warm for 2-4 h, and then post-treatment is carried out to obtain the ball milling modifier.

8. An environmentally friendly low-smoke and halogen-free insulating cable compound according to claim 7, characterized in that, The dosage ratio of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine, N,N-dimethylformamide and 5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride is 4.0-4.4 g: 30-36 mL: 3.6-4.0 g.

9. A preparation method of a low-smoke and halogen-free environment-friendly insulating cable material as described in any one of claims 1-8, characterized in that, Crosslinked polypropylene, a plasticizer, a stabilizer, a lubricant and an antioxidant are added into a twin-screw extruder, melted and extruded, and then naturally cured to obtain an insulating cable material.

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