Halogen-free flame-retardant polyolefin cable material and method for producing the same

Abstract

This invention relates to the field of polymer material modification technology, and discloses a halogen-free flame-retardant polyolefin cable material and its preparation method. The material comprises linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate terpolymer, active zinc oxide, synthetic hydrotalcite, antioxidant, lubricant, and interface-solventized modified flame-retardant powder, which are reacted and extruded. The modified flame-retardant powder is formed by coating diethylphosphinate aluminum and anhydrous zinc borate with liquid bisphenol A-bis(diphenyl phosphate). This invention utilizes the steric hindrance effect to regulate the reaction kinetics of the epoxy-containing compatibilizer by constructing an interface-solventized layer and combining it with a side-feeding process, preventing premature crosslinking and inducing in-situ chemical bonding. The resulting cable material possesses both excellent flame retardant rating (UL94 V-0) and high elongation at break, effectively solving the technical challenge of balancing mechanical properties and processing stability in high-filler systems.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification technology, specifically to a halogen-free flame-retardant polyolefin cable material and its preparation method. Background Technology

[0002] With increasingly stringent safety and environmental requirements for cable materials, halogen-free flame-retardant polyolefin cable materials have become the industry mainstream. Because polyolefin resins themselves have a low limiting oxygen index, large amounts of inorganic flame retardants are typically required to meet stringent flame-retardant standards. However, this high-filler system presents significant technical bottlenecks in practical applications.

[0003] The inherent polarity difference between inorganic flame retardants and organic resin matrices leads to poor interfacial compatibility. In conventional processing, even with surface treatment using silane or titanate coupling agents, the contact between inorganic particles and the resin matrix remains primarily rigid. At high filler contents, this rigid interface struggles to effectively transfer stress, resulting in numerous microscopic defects and stress concentration points within the material. This reduces the cable material's elongation at break, impairs its flexibility, and makes it difficult to meet crack resistance requirements in complex laying environments.

[0004] To improve interfacial adhesion strength, existing technologies often introduce reactive compatibilizers containing active functional groups (such as epoxy groups). Although epoxy groups can theoretically chemically bond with the hydroxyl groups on the flame retardant surface to strengthen the interface, this reaction is often difficult to control in actual reactive extrusion processes. Due to the high reactivity of epoxy groups, compatibilizers tend to prematurely and rapidly crosslink with the flame retardant surface in the feed or initial melting stages of the extruder. This uncontrollable early reaction leads to a sharp increase in melt viscosity during the plasticizing stage, causing uneven material dispersion and even the formation of locally crosslinked microgel points, severely affecting the stability of the extrusion process and the surface quality of the final product.

[0005] A single flame retardant system often fails to simultaneously meet the dual requirements of gas-phase flame retardancy and condensed-phase char formation. This necessitates increasing the amount of flame retardant used to achieve high flame retardancy ratings, which in turn exacerbates the deterioration of mechanical properties and increases processing difficulty. Therefore, how to balance the mechanical toughness and processing stability of materials by optimizing the interface structure and controlling the reaction process while ensuring high flame retardancy ratings is a pressing issue in the field of halogen-free flame-retardant polyolefin cable materials. Summary of the Invention

[0006] The technical problem solved by this invention is that existing halogen-free flame-retardant polyolefin cable materials require high levels of inorganic flame retardants to meet flame retardant standards, resulting in poor material interfacial compatibility, low mechanical toughness, and insufficient processing fluidity. Furthermore, the uncontrollable reaction of the active compatibilizer can easily cause scorching or uneven dispersion during processing.

[0007] To address the above problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a halogen-free flame-retardant polyolefin cable material, which adopts the following technical solution:

[0009] A halogen-free flame-retardant polyolefin cable material is prepared by reactive extrusion of the following raw materials in parts by weight: 45.0-55.0 parts of linear low-density polyethylene; 10.0-15.0 parts of ethylene-vinyl acetate copolymer; 5.0-8.0 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer; 39.5-53.0 parts of interface-solvent-modified flame-retardant powder; 0.5-1.0 parts of active zinc oxide; 0.3-0.6 parts of synthetic hydrotalcite; 0.4-1.0 parts of antioxidant; and 0.3-0.5 parts of lubricant. The interface-solvent-modified flame-retardant powder comprises aluminum diethylphosphinate, anhydrous zinc borate, and bisphenol A-bis(diphenyl phosphate) coated on the surfaces of aluminum diethylphosphinate and anhydrous zinc borate.

[0010] By employing the above technical solution, the high viscosity and chemical activity of liquid bisphenol A-bis(diphenyl phosphate) are utilized to construct a solvated interface layer between the resin matrix and inorganic flame-retardant particles, and to induce a controlled chemical bonding reaction. The specific mechanism and effects are as follows:

[0011] Interfacial solvation and wetting: Bisphenol A-bis(diphenyl phosphate), a high-boiling-point liquid organophosphate, coats the surfaces of aluminum diethylphosphinate and anhydrous zinc borate to form a liquid film. This liquid film fills the microscopic voids between the polyolefin resin matrix and the inorganic powder, transforming the rigid solid-solid contact between the resin and powder into a viscoelastic solid-liquid-solid contact. This solvated interface reduces interphase surface energy, decreases frictional heat during extrusion, promotes uniform dispersion of high-filler-content flame retardants in the matrix, and reduces stress concentration points caused by particle agglomeration.

[0012] Reaction kinetics control and in-situ grafting: The reaction process of epoxy groups in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer was controlled by the physical steric hindrance effect of the interfacial liquid film and the thermal shearing effect of reactive extrusion.

[0013] Phase 1 (Physical Shielding): During the feeding section and initial melting stage of the extrusion process, a bisphenol A-bis(diphenyl phosphate) liquid film covers the surface of inorganic particles, physically blocking the active hydroxyl groups on the particle surface and delaying the contact between the epoxy groups in the compatibilizer and the hydroxyl groups, thereby preventing cross-linking and scorching of the material before plasticization is complete.

[0014] Stage Two (In-situ Reaction): Upon entering the reaction section, under high temperature and strong shear force, the molecular chains of the ethylene-methyl acrylate-glycidyl methacrylate terpolymer diffuse through the liquid film, exposing and activating the epoxy groups on its side chains. The three-membered ring structure in the epoxy groups undergoes a ring-opening addition reaction with the hydroxyl groups on the surfaces of aluminum diethylphosphines and anhydrous zinc oxide, catalyzed by anhydrous zinc borate and activated zinc oxide, to form ether bonds. This chemical reaction forms strong covalent bonds at the interface, increasing the interfacial bonding strength.

[0015] Multiphase synergistic flame retardancy: A flame retardant system synergistically integrates gas, condensed, and liquid phases. Aluminum diethylphosphonate decomposes upon heating to generate phosphorus-containing free radicals, which capture free radicals in the combustion chain reaction in the gas phase. Anhydrous zinc borate melts upon heating to form a glassy capping layer, promoting the formation of the condensed-phase char layer. Bisphenol A-bis(diphenyl phosphate) at the interface plasticizes and stabilizes the char layer during combustion, preventing cracking due to high brittleness. The synergistic effect of these three components achieves a UL94V-0 flame retardancy rating with a relatively low total addition amount.

[0016] Preferably, the antioxidant is a compound of antioxidant 1010 and antioxidant 168; the lubricant is vinyl bis-stearamide.

[0017] By adopting the above technical solution, the synergistic effect of antioxidant 1010 and antioxidant 168 can effectively inhibit the thermal oxidative degradation of polymers during high-temperature reactive extrusion and protect the polymer backbone; vinyl bis-stearamide, as an internal and external lubricant, balances the plasticizing time and flowability of the material and reduces the risk of material accumulation in the die head.

[0018] Preferably, the interface solvation modified flame retardant powder is made from the following raw materials in parts by weight: 35-45 parts of aluminum diethylphosphinate; 3-5 parts of anhydrous zinc borate; and 1.5-3.0 parts of liquid bisphenol A-bis(diphenyl phosphate); and the interface solvation modified flame retardant powder is applied by an atomization spraying process to form a solvation liquid film of liquid bisphenol A-bis(diphenyl phosphate) on the surfaces of aluminum diethylphosphinate and anhydrous zinc borate.

[0019] By adopting the above technical solution, the specific formulation ensures the efficiency of aluminum diethylphosphinate as the main flame retardant, while anhydrous zinc borate provides a sufficient char-forming skeleton as a synergist and smoke suppressant. The atomized spraying process ensures that the liquid components can be uniformly spread on the powder surface in the form of micron-sized droplets, forming a continuous and uniformly thick solvated liquid film, avoiding local agglomeration or incomplete coating of the liquid, and ensuring the consistency of the interfacial reaction in subsequent reactive extrusion.

[0020] Preferably, in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer, the content of methyl acrylate is 20-30 wt%, and the content of glycidyl methacrylate is 2-8 wt%.

[0021] By adopting the above technical solution, the methyl acrylate segment provides flexibility and polarity to the polymer chain, increasing the physical affinity with inorganic fillers; the limitation of glycidyl methacrylate content ensures that there are enough epoxy groups to participate in interfacial chemical bonding, and prevents the material processing rheological properties from deteriorating or gel formation due to excessively high crosslinking point density.

[0022] Preferably, the halogen-free flame-retardant polyolefin cable material has a multiphase structure, wherein the linear low-density polyethylene, ethylene-vinyl acetate copolymer and ethylene-methyl acrylate-glycidyl methacrylate terpolymer constitute a continuous phase matrix, the interface-solventized modified flame-retardant powder is distributed as a dispersed phase in the continuous phase matrix, and the liquid bisphenol A-bis(diphenyl phosphate) is located in the interface layer between the dispersed phase and the continuous phase matrix.

[0023] By adopting the above technical solution, the microstructure of the material was clarified. In this specific continuous-dispersed phase structure, the continuous phase matrix undertakes the main function of mechanical stress transmission, the dispersed phase provides flame retardant function, and the liquid bisphenol A-bis(diphenyl phosphate) layer at the interface acts as a flexible buffer layer and reactive bonding layer. When subjected to external impact or tension, it can absorb energy through its own deformation and transfer stress through chemical bonding points, thereby endowing the material with high elongation at break and excellent impact resistance.

[0024] Secondly, this invention provides a method for preparing halogen-free flame-retardant polyolefin cable material, employing the following technical solution:

[0025] A method for preparing halogen-free flame-retardant polyolefin cable material includes the following steps: linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate terpolymer, active zinc oxide, synthetic hydrotalcite, antioxidant, and lubricant are mixed uniformly to obtain a stabilized resin premix; aluminum diethylphosphinate and anhydrous zinc borate are mixed and heated, and liquid bisphenol A-bis(diphenyl phosphate) is atomized and sprayed in under high-speed stirring; after cooling, a dry, flowing interface-solvent-modified flame-retardant powder is obtained; reactive extrusion granulation is performed using a twin-screw extruder, the stabilized resin premix is ​​added to the main feed port of the twin-screw extruder, and the interface-solvent-modified flame-retardant powder is added to the side feed port of the twin-screw extruder; the mixture is melted, reacted, extruded, air-cooled, and pelletized to obtain the halogen-free flame-retardant polyolefin cable material.

[0026] By adopting the above technical solution, this invention solves the problems of difficult-to-control interfacial reactions and uneven dispersion in reactive extrusion of highly filled flame-retardant systems through a step-feeding process combined with interfacial pre-solventization. The specific process mechanism and reaction process are as follows:

[0027] Matrix resin preplasticization stage: The stabilized resin premix is ​​first added to the main feed port of the twin-screw extruder. In the section before the side feed port, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and terpolymer containing epoxy groups are melt-plasticized under shear heat. No inorganic flame retardant is introduced at this stage, avoiding wear on the screw and barrel by high-hardness particles, while ensuring that the compatibilizer molecular chains are fully extended in the melt, exposing their reactive sites.

[0028] Interfacial wetting and dispersion stage: The interfacially solvated modified flame retardant powder is forcibly pressed into the melt through the side feed port. Because the powder surface is pre-coated with a liquid bisphenol A-bis(diphenyl phosphate) solvation layer, this liquid layer rapidly reduces the interfacial tension between the inorganic particles and the organic melt upon contact with the high-temperature melt, promoting the rapid deagglomeration and uniform dispersion of the inorganic particles in the resin matrix.

[0029] In-situ chemical bonding reaction stage: In the reaction bonding section, under the action of the screw's strong shear mixing element, a controlled chemical reaction occurs at the interface.

[0030] Reaction initiation: High temperature and shearing cause the epoxy groups of the ethylene-methyl acrylate-glycidyl methacrylate terpolymer to overcome steric hindrance, diffuse into the solvated liquid film, and contact the flame retardant surface.

[0031] Ring-opening grafting: Under the catalysis of Lewis acids (active zinc oxide and anhydrous zinc borate), the epoxy ring on the glycidyl methacrylate segment undergoes a ring-opening reaction. The epoxy group undergoes nucleophilic addition with the hydroxyl groups on the surface of aluminum diethylphosphinate or anhydrous zinc borate, breaking the epoxy bond to form an ether bond, accompanied by the formation of secondary hydroxyl groups.

[0032] Structural solidification: The above reaction anchors inorganic flame-retardant particles to the resin macromolecular chain in the form of chemical bonds. As the melt enters the stabilization section and cools down, this chemical cross-linking network is fixed, forming a stable interfacial phase structure.

[0033] Preferably, the preparation process of the interface solvation modified flame retardant powder is as follows: aluminum diethylphosphinate and anhydrous zinc borate are put into a mixer, and the heating jacket is turned on to raise the material temperature to 85-95°C; while keeping the material temperature constant, the liquid bisphenol A-bis(diphenyl phosphate) is uniformly sprayed into the mixer at a stirring speed of 600-800 rpm through an atomizing nozzle at a rate of 50-100 g / min; after spraying, the high-speed stirring is maintained for 5-8 minutes, and then the material is unloaded into a cooling mixer to cool to below 40°C.

[0034] By adopting the above technical solution, the heating temperature is set at 85-95℃ to reduce the viscosity of liquid bisphenol A-bis(diphenyl phosphate) and increase the surface energy of the inorganic powder, making it more conducive to spreading. High-speed stirring combined with low-rate atomization spraying ensures that the liquid contacts the powder in the form of extremely fine droplets, preventing powder agglomeration due to excessive local liquid. The cooling step is used to fix the coating layer, prevent the powder from sticking together during storage, and ensure its flow stability during side feeding.

[0035] Preferably, in the reactive extrusion granulation process: the length-to-diameter ratio of the twin-screw extruder used is 44:1-48:1; the side feed port is located at 20D-24D of the extruder.

[0036] By adopting the above technical solution, an aspect ratio of 44:1-48:1 provides sufficient process length to complete the entire process of melting, dispersion, reaction, and devolatilization. Setting the side feed port at 20D-24D is crucial for reaction control: the first 20D-24D length ensures complete melting of the resin matrix and pre-dispersion of the additives; the remaining 20D-24D length provides precise residence time for the dispersion of highly filled flame retardants and interfacial chemical reactions, ensuring sufficient reaction while avoiding excessive resin thermal degradation or over-crosslinking due to excessive residence time.

[0037] Preferably, the temperature settings for each zone of the twin-screw extruder are as follows: Zones 1 to 4 are the melting and acid removal zones, with a temperature set at 160℃-175℃; Zones 5 to 8 are the reaction and bonding zones, with a temperature set at 190℃-200℃; Zone 9 to the die head is the stabilization zone, with a temperature set at 165℃-175℃; and the screw speed is set at 300-500 rpm.

[0038] By adopting the above technical solution, a stepped temperature distribution was established to match the reaction process:

[0039] Melting and acid removal section (160-175℃): The lower temperature is used for resin melting, and at the same time, synthetic hydrotalcite is used to adsorb any acidic residues that may be present at this temperature, preventing them from interfering with subsequent catalytic reactions.

[0040] Reaction bonding section (190-200℃): Increase the temperature to overcome the activation energy barrier of the epoxy ring-opening reaction and accelerate the formation rate of chemical bonds.

[0041] Stabilization section (165-175℃): Lower the temperature to terminate free radical side reactions, increase melt viscosity to build up die head pressure, and ensure the compactness of the extruded strip.

[0042] Preferably, during the reactive extrusion granulation process, a vacuum treatment is performed in the stabilization section, and the vacuum degree is controlled between -0.06 MPa and -0.09 MPa.

[0043] By employing the above technical solution, high-vacuum treatment is performed in the stabilization phase after the reaction, which forcibly removes trace amounts of moisture, air, and low-molecular-weight volatiles that are easily generated during the reaction from the raw materials. This eliminates porosity defects inside the cable material and further improves the material's breakdown voltage strength and mechanical density.

[0044] This invention provides a halogen-free flame-retardant polyolefin cable material and its preparation method. It has the following beneficial effects:

[0045] 1. This invention utilizes liquid bisphenol A-bis(diphenyl phosphate) to solvate and coat inorganic flame-retardant powders, solving the problem of poor interfacial wettability in highly filled flame-retardant systems. The high-viscosity liquid phosphate film fills the microscopic interfacial voids between the resin matrix and inorganic particles, transforming rigid physical contact into a solvated interface with deformation capabilities. This modification reduces interphase surface tension and frictional heat during processing, promotes homogeneous dispersion of flame-retardant particles in the polyolefin matrix, and avoids structural defects caused by particle agglomeration.

[0046] 2. This invention achieves control over the chemical reaction process of epoxy-containing compatibilizers through the physical steric hindrance effect of the interfacial solvation layer. The BDP liquid film shields the active sites on the surface of the inorganic flame retardant during the initial extrusion process, preventing premature and rapid crosslinking of the ethylene-methyl acrylate-glycidyl methacrylate terpolymer. In subsequent reaction zones, a controlled in-situ grafting reaction is induced by shear and heat to construct a chemically bonded interface. This interfacial structure effectively transfers tensile stress, endowing the material with excellent elongation at break and impact resistance.

[0047] 3. This invention constructs a multi-component flame-retardant system with synergistic effects in the gas, condensed, and liquid phases. Aluminum diethylphosphinate captures free radicals in the gas phase, anhydrous zinc borate promotes the formation of a hard char layer in the condensed phase, and bisphenol A-bis(diphenyl phosphate), as a liquid-phase flame retardant, plasticizes the char layer during combustion, preventing char layer embrittlement. With the synergistic catalytic effect of active zinc oxide and synthetic hydrotalcite, the total amount of flame retardant added is reduced, ensuring that the material can quickly form a dense and continuous heat-insulating oxygen barrier, stably meeting the UL94 V-0 flame retardant standard. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Preparation Examples 1-4:

[0050] Preparation Example 1:

[0051] This preparation example provides a method for preparing an interfacial solvation modified flame retardant powder (intermediate A1), including the following steps:

[0052] 35 kg of aluminum diethylphosphinate and 3 kg of anhydrous zinc borate were added to a high-speed mixer with a heating jacket. The stirring speed was set to 300 rpm, and the heating jacket was turned on to raise the material temperature to 85°C. The material temperature was kept constant, and the stirring speed was increased to 600 rpm. 1.5 kg of liquid bisphenol A-bis(diphenyl phosphate) (hereinafter referred to as BDP) was uniformly sprayed into the mixer at a rate of 50 g / min through an atomizing nozzle. After spraying, the mixture was stirred at high speed for 5 minutes. The material was then unloaded into a cooling mixer and cooled to below 40°C to obtain a dry and flowing interfacial solvation modified flame retardant powder intermediate A1.

[0053] Preparation Example 2:

[0054] This preparation example provides a method for preparing an interfacial solvation modified flame retardant powder (intermediate A2), comprising the following steps:

[0055] 40 kg of aluminum diethylphosphinic acid and 4 kg of anhydrous zinc borate were added to a high-speed mixer with a heating jacket. The stirring speed was set to 350 rpm, and the heating jacket was turned on to raise the material temperature to 90°C. The material temperature was kept constant, and the stirring speed was increased to 700 rpm. 2.2 kg of BDP was sprayed evenly through an atomizing nozzle at a rate of 75 g / min. After spraying, the high-speed stirring was maintained for 6 minutes. Then the material was unloaded into a cooling mixer and cooled to below 40°C to obtain a dry and flowing interfacial solvation modified flame retardant powder intermediate A2.

[0056] Preparation Example 3:

[0057] This preparation example provides a method for preparing an interfacial solvation modified flame retardant powder (intermediate A3), including the following steps:

[0058] 45 kg of aluminum diethylphosphinic acid and 5 kg of anhydrous zinc borate were added to a high-speed mixer with a heating jacket. The stirring speed was set to 400 rpm, and the heating jacket was turned on to raise the material temperature to 95°C. The material temperature was kept constant, and the stirring speed was increased to 800 rpm. 3.0 kg of BDP was uniformly sprayed in through an atomizing nozzle at a rate of 100 g / min. After spraying, the high-speed stirring was maintained for 8 minutes. Then the material was unloaded into a cooling mixer and cooled to below 40°C to obtain a dry and flowing interfacial solvation modified flame retardant powder intermediate A3.

[0059] Preparation Example 4:

[0060] This preparation example provides a general method for preparing a stabilized resin premix (intermediate B), including the following steps:

[0061] Metered linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate terpolymer, active zinc oxide, synthetic hydrotalcite, antioxidant 1010, antioxidant 168, and lubricant EBS were added to a low-speed tumbling mixer. In the ethylene-methyl acrylate-glycidyl methacrylate terpolymer, the content of methyl acrylate was 20-30 wt%, and the content of glycidyl methacrylate was 2-8 wt%. The mixture was stirred at 40 rpm for 8 minutes at room temperature of 25°C to ensure that the components were macroscopically uniformly dispersed, thus obtaining stabilized resin premix intermediate B.

[0062] Examples 1-3:

[0063] Example 1:

[0064] This embodiment provides a halogen-free flame-retardant polyolefin cable material based on interface solvation-controlled reaction kinetics and its preparation method. The raw material components, by weight, include the following steps:

[0065] (1) Preparation of stabilized resin premix (intermediate B1):

[0066] Weigh out 55.0 parts of linear low-density polyethylene, 10.0 parts of ethylene-vinyl acetate copolymer, 5.0 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer, 0.5 parts of active zinc oxide, 0.3 parts of synthetic hydrotalcite, 0.2 parts of antioxidant 1010, 0.2 parts of antioxidant 168, and 0.3 parts of lubricant EBS; put the above raw materials into a low-speed tumbling mixer and mix them according to the method described in Preparation Example 4 to obtain stabilized resin premix intermediate B1.

[0067] (2) Reactive extrusion granulation:

[0068] A co-rotating twin-screw extruder with a length-to-diameter ratio of 44:1 was used; intermediate B1 obtained in step (1) was added to the main feed port of the extruder; 39.5 parts of the interfacial solvation modified flame retardant powder (intermediate A1) prepared in Preparation Example 1 was added to the side feed port of the extruder located at 20D.

[0069] The temperatures of each zone of the extruder are set as follows: Zones 1 to 4 (melting and acid removal section) are 160℃-175℃, Zones 5 to 8 (reaction and bonding section) are 190℃, and Zone 9 to the die head (stabilization section) is 165℃; the screw speed is set to 300 rpm, and a vacuum of -0.06 MPa is drawn in the later section of the reaction zone. After extrusion, air cooling, and pelletizing, halogen-free flame-retardant polyolefin cable material is obtained.

[0070] Example 2:

[0071] This embodiment provides a halogen-free flame-retardant polyolefin cable material based on interface solvation-controlled reaction kinetics and its preparation method. The raw material components, by weight, include the following steps:

[0072] (1) Preparation of stabilized resin premix (intermediate B2):

[0073] Weigh out 50.0 parts of linear low-density polyethylene, 12.5 parts of ethylene-vinyl acetate copolymer, 6.5 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer, 0.75 parts of active zinc oxide, 0.45 parts of synthetic hydrotalcite, 0.35 parts of antioxidant 1010, 0.35 parts of antioxidant 168, and 0.4 parts of lubricant EBS; put the above raw materials into a low-speed tumbling mixer and mix them according to the method described in Preparation Example 4 to obtain stabilized resin premix intermediate B2.

[0074] (2) Reactive extrusion granulation:

[0075] A co-rotating twin-screw extruder with a length-to-diameter ratio of 44:1 was used; intermediate B2 obtained in step (1) was added to the main feed port of the extruder; 46.2 parts of the interfacial solvation modified flame retardant powder (intermediate A2) prepared in Preparation Example 2 were added to the side feed port of the extruder located at 22D;

[0076] The temperatures of each zone of the extruder are set as follows: Zones 1 to 4 (melting and acid removal section) are 160℃-175℃, Zones 5 to 8 (reaction and bonding section) are 195℃, and Zone 9 to the die head (stabilization section) is 170℃; the screw speed is set to 400 rpm, and a vacuum is drawn to -0.08 MPa in the later section of the reaction zone. After extrusion, air cooling, and pelletizing, halogen-free flame-retardant polyolefin cable material is obtained.

[0077] Example 3:

[0078] This embodiment provides a halogen-free flame-retardant polyolefin cable material based on interface solvation-controlled reaction kinetics and its preparation method. The raw material components, by weight, include the following steps:

[0079] (1) Preparation of stabilized resin premix (intermediate B3):

[0080] Weigh out 45.0 parts of linear low-density polyethylene, 15.0 parts of ethylene-vinyl acetate copolymer, 8.0 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer, 1.0 part of active zinc oxide, 0.6 parts of synthetic hydrotalcite, 0.5 parts of antioxidant 1010, 0.5 parts of antioxidant 168, and 0.5 parts of lubricant EBS; put the above raw materials into a low-speed tumbling mixer and mix them according to the method described in Preparation Example 4 to obtain stabilized resin premix intermediate B3.

[0081] (2) Reactive extrusion granulation:

[0082] A co-rotating twin-screw extruder with a length-to-diameter ratio of 48:1 was used; intermediate B3 obtained in step (1) was added to the main feed port of the extruder; 53.0 parts of the interfacial solvation modified flame retardant powder (intermediate A3) prepared in Preparation Example 3 were added to the side feed port of the extruder located at 24D.

[0083] The temperatures of each zone of the extruder are set as follows: Zones 1 to 4 (melting and acid removal section) are 160℃-175℃, Zones 5 to 8 (reaction and bonding section) are 200℃, and Zone 9 to the die head (stabilization section) is 175℃; the screw speed is set to 500 rpm, and a vacuum is drawn to -0.09 MPa in the later section of the reaction zone. After extrusion, air cooling, and pelletizing, halogen-free flame-retardant polyolefin cable material is obtained.

[0084] Performance testing:

[0085] To verify the performance of the halogen-free flame-retardant polyolefin cable material prepared in this invention, the following performance tests were conducted on the cable material particles prepared in Examples 1-3:

[0086] Tensile property test: The test was conducted in accordance with GB / T1040.2-2006 standard. The cable material was pressed into dumbbell-shaped strips, and the tensile speed was set to 250 mm / min. The tensile strength and elongation at break were recorded.

[0087] Flame retardant performance test: Vertical burning test was conducted according to UL94 standard, with a sample thickness of 1.6 mm, and the flame retardant rating was recorded.

[0088] The test results are shown in Table 1:

[0089] Table 1. Performance test results of halogen-free flame-retardant polyolefin cable materials in Examples 1-3

[0090] project Example 1 Example 2 Example 3 Limitation Standards Tensile strength (MPa) 15.2 13.8 12.5 ≥12.0 Elongation at break (%) 580 520 465 ≥450 Flame retardant rating (UL94) V-0 V-0 V-0 V-0

[0091] Data Analysis:

[0092] As can be seen from Table 1, the halogen-free flame-retardant polyolefin cable materials prepared in Examples 1-3 all have excellent mechanical properties and flame-retardant properties.

[0093] As the amount of flame retardant powder added increased (from Example 1 to Example 3), the tensile strength and elongation at break decreased slightly, which is typical of highly filled composite materials. However, even in Example 3, which had the highest amount of flame retardant powder, the tensile strength remained at 12.5 MPa and the elongation at break remained at 465%, both of which were better than the lower limit values ​​(12 MPa and 450%) set in claim 5.

[0094] All embodiments passed the UL94 V-0 flame retardant test, demonstrating that the interface solvation modified flame retardant powder was well dispersed in the matrix and that the reactive extrusion process effectively preserved the flame retardant performance of the material.

[0095] Comparative Examples 1-5:

[0096] Comparative Example 1:

[0097] This comparative example provides a conventional halogen-free flame-retardant polyolefin cable material. The difference compared to Example 2 is:

[0098] (1) No bisphenol A-bis(diphenyl phosphate) (BDP) and synthetic hydrotalcite are added to the raw material components;

[0099] (2) Replace 6.5 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer (E-MA-GMA) with an equal amount of maleic anhydride grafted polyolefin elastomer (POE-g-MAH).

[0100] (3) The preparation process adopts a one-step method, that is, after all the raw materials are mixed in a high-speed mixer, they are directly added to the main feed port of the extruder for extrusion granulation;

[0101] The types and amounts of the remaining raw materials are the same.

[0102] Comparative Example 2:

[0103] This comparative example provides a halogen-free flame-retardant polyolefin cable material lacking an interface buffer layer. The difference compared to Example 2 is:

[0104] (1) No bisphenol A-bis(diphenyl phosphate) (BDP) is added to the raw material components.

[0105] (2) During the preparation process, the preparation step of intermediate A2 is cancelled, and 40.0 parts of aluminum diethylphosphinate and 4.0 parts of anhydrous zinc borate mixed dry powder are directly added to the side feed port;

[0106] The types, amounts, and process parameters of all other raw materials are the same.

[0107] Comparative Example 3:

[0108] This comparative example provides a halogen-free flame-retardant polyolefin cable material lacking an acid removal system. The difference compared to Example 2 is:

[0109] (1) No synthetic hydrotalcite is added to the raw material components;

[0110] The types, amounts, and preparation processes of the other raw materials are all the same.

[0111] Comparative Example 4:

[0112] This comparative example provides a halogen-free flame-retardant polyolefin cable material employing different reactive functional groups. The difference compared to Example 2 is:

[0113] (1) Replace 6.5 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer (E-MA-GMA) with an equal amount of maleic anhydride grafted polyolefin elastomer (POE-g-MAH).

[0114] The types, amounts, and preparation processes of the other raw materials are all the same.

[0115] Comparative Example 5:

[0116] This comparative example provides a halogen-free flame-retardant polyolefin cable material using a different feeding process. The difference compared to Example 2 is:

[0117] (1) Change the feeding sequence in the preparation process and do not use the side feeding process;

[0118] (2) Intermediate B2 (containing resin and additives) and intermediate A2 (containing flame retardant) are premixed evenly before extrusion and then fed into the extruder through the main feed port;

[0119] The types and amounts of other raw materials and the extrusion temperature profiles are all the same.

[0120] Test Examples 1-4:

[0121] Test Example 1:

[0122] This test case aims to evaluate the rheological stability of different formulation systems and process routes during extrusion processing, and to verify the role of interfacial solvation systems and acid scavengers in inhibiting early crosslinking (scorching) and improving surface quality.

[0123] Experimental steps:

[0124] (1) During the extrusion granulation process of Examples 1-3 and Comparative Examples 1-5, the temperature zones of the extruder were kept at the set values ​​and operated continuously and stably for 30 minutes.

[0125] (2) Record the percentage of main torque and the melt pressure of the die head through the extruder control system. Record the data once every 5 minutes and take the arithmetic mean of the three recorded values ​​as the test result.

[0126] (3) Visually observe the surface condition of the extruded sample at the die outlet and record whether there is melt fracture, pores, roughness or visible particles.

[0127] (4) Collect the stable extruded particles and dry them in a vacuum oven at 100°C for 4 hours. According to the standard test method of ASTM D1238 for determining the melt flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics, test the melt flow rate (MFR) at 190°C and 2.16kg load. Test 5 groups for each sample and take the average value.

[0128] Experimental data:

[0129] Table 2. Processing rheological parameters and surface quality test results of different systems

[0130] Group Main unit torque load (%) Melt pressure at the die head (MPa) Melt flow rate (MFR) (g / 10min) Surface appearance of extruded strip Example 1 56.4 11.2 1.45 Smooth and glossy, with uniform color Example 2 61.8 12.5 1.32 Smooth and glossy, without defects Example 3 68.3 13.8 1.15 Smooth, free of visible particles Comparative Example 1 74.5 15.1 0.94 The surface is slightly rough and has low gloss. Comparative Example 2 86.2 18.4 0.65 Extremely rough surface, accompanied by sharkskin-like skin. Comparative Example 3 63.5 12.9 0.12 The surface is covered with numerous microcrystalline dots, giving it a dry feel. Comparative Example 4 69.1 14.3 1.08 The surface is relatively smooth, with occasional flow marks. Comparative Example 5 83.7 17.6 0.48 Extrusion swells severely, surface deformed

[0131] Conclusion Analysis:

[0132] According to the data in Table 2, the host torque load in Examples 1-3 was between 56.4% and 68.3%, the MFR value was maintained between 1.15 and 1.45 g / 10min, and the sample surface was smooth. The liquid film formed by BDP on the powder surface provided wetting and lubrication, reduced the frictional resistance between the highly filled powder and the screw, and isolated the active groups, ensuring processing flowability.

[0133] In Comparative Example 2, the main engine torque increased to 86.2%, the MFR decreased to 0.65 g / 10 min, and melt fracture appeared on the surface. The lack of physical isolation from the interfacial solvation layer allowed the GMA epoxy groups to prematurely contact and react with the ADP surface active sites under shear stress, leading to a surge in melt viscosity and the formation of localized cross-linked networks.

[0134] In Comparative Example 3, the MFR decreased to 0.12 g / 10 min, and fine crystal points were distributed on the surface. The acidic substances released by the thermal decomposition of EVA in the system were not neutralized, and the acid catalysis accelerated the self-polymerization or side reactions of epoxy groups, resulting in the formation of micro-gel particles.

[0135] The main engine torque of Comparative Example 5 was 83.7%, and the MFR was 0.48 g / 10 min. The change in the raw material mixing method caused the reactive components to come into contact during solid conveying and the initial melting stage. This made it impossible to delay the reaction kinetics using step feeding and temperature control processes, resulting in the reaction occurring in an uncontrolled stage and affecting processing stability.

[0136] Test Example 2:

[0137] This test case aims to evaluate the mechanical properties of the material and its performance retention rate under humid and hot conditions, thereby verifying the formation and stability of interfacial chemical bonding and distinguishing the differences in micro-interfacial bonding strength between physical coating and in-situ catalytic chemical welding.

[0138] Experimental steps:

[0139] (1) The cable material particles prepared in Examples 1-3 and Comparative Examples 1-5 were dried at 90°C for 4 hours. They were then injection molded in a temperature range of 180°C-200°C using an injection molding machine to prepare Type IV specimens conforming to ASTM D638 standard. Twenty specimens were prepared in each group and placed in an environment of 23±2°C and 50±5% relative humidity for 24 hours.

[0140] (2) Take 10 samples from each group for room temperature tensile testing. Set the tensile rate to 50 mm / min, record the initial tensile strength and elongation at break, and take the average value.

[0141] (3) Immerse the remaining 10 specimens in each group completely in an 85°C constant temperature water bath for 168 hours, remove them, wipe off the surface moisture, and let them stand and cool in a standard environment for 4 hours.

[0142] (4) Perform tensile tests on the specimens after wet heat treatment, with the same test conditions as in step (2), record the tensile strength and elongation at break after aging, and calculate the elongation at break retention rate.

[0143] Experimental data

[0144] Table 3. Results of Mechanical Properties and Damp Heat Aging Resistance Tests

[0145] Group Initial tensile strength (MPa) Initial elongation at break (%) Tensile strength after aging (MPa) Elongation at break after aging (%) Elongation at break retention rate (%) Example 1 17.8 542 16.9 498 91.9 Example 2 18.4 515 17.2 466 90.5 Example 3 19.1 483 17.5 427 88.4 Comparative Example 1 12.3 210 9.4 115 54.8 Comparative Example 2 14.5 320 11.2 185 57.8 Comparative Example 3 13.8 285 8.9 104 36.5 Comparative Example 4 15.6 365 13.1 262 71.8 Comparative Example 5 13.2 245 10.5 142 58.0

[0146] Conclusion Analysis:

[0147] According to the data in Table 3, the initial tensile strength of Examples 1-3 was 17.8-19.1 MPa, and the elongation at break was between 483% and 542%. After immersion in hot water at 85°C, the elongation at break retention rate exceeded 88%. The GMA epoxy groups reacted with the ADP surface under the action of ZnO to form a chemically bonded interface. This structure, while transferring matrix stress, remained stable under these hydrothermal conditions, inhibiting interfacial debonding.

[0148] Comparative Example 1 (physical blend) had an initial elongation at break of 210% and a retention rate of 54.8% after aging. The inorganic powder and the matrix are mainly in physical contact. Under humid and hot conditions, moisture enters the phase boundary, destroying the physical adsorption and leading to a decline in performance.

[0149] The initial elongation and retention of Comparative Example 4 were lower than those of the Example. Under specific component and temperature conditions in this system, ZnO exhibited better catalytic grafting effect on epoxy groups than on acid anhydride groups, and the GMA-ZnO system showed higher efficiency in constructing the interfacial layer.

[0150] The retention rate of Comparative Example 3 after aging was 36.5%. The acidic products generated by the decomposition of EVA in the system accelerated the degradation of the matrix and the damage to the interface in a humid and hot environment, which confirmed the role of hydrotalcite in maintaining the humid and hot stability of the material.

[0151] Test Example 3:

[0152] This test case aims to evaluate the limiting oxygen index, vertical flammability rating, volume resistivity, and corrosivity of materials to metallic conductors, and to verify the protective effect of the acid removal system on electrical performance and the influence of interface structure on insulation stability.

[0153] Experimental steps:

[0154] (1) The particles of Examples 1-3 and Comparative Examples 1-5 were pressed into shape on a flat vulcanizing machine at 180°C and 10MPa pressure to prepare standard samples with thicknesses of 3.2 mm and 1.6 mm.

[0155] (2) The limiting oxygen index was tested according to the ASTM D2863 test standard for the minimum oxygen content required for sustained combustion of plastic materials.

[0156] (3) Perform a vertical burning test according to the UL-94 standard, record whether the cotton was ignited by dripping and the burning time, and determine the flame retardant rating.

[0157] (4) According to ASTM D257, the standard test method for measuring the DC resistance or conductivity of insulating materials, the volume resistivity was tested using a high resistance meter at a DC voltage of 500V. The test was divided into two groups: one group was tested in a dry state at 23℃; the other group was tested in a wet state after the sample was soaked in distilled water at 23℃ for 24 hours and then the surface was wiped dry.

[0158] (5) Conduct copper foil corrosion test according to ASTM D2671 test method for heat shrink tubing. Wrap the polished electrolytic copper foil tightly around the sample surface and place it in an aging chamber at 100°C for 168 hours. Observe the discoloration, black spots or pitting on the copper foil surface.

[0159] Experimental data:

[0160] Table 4. Test results of flame retardant and electrical insulation properties

[0161] Group Limiting Oxygen Index (LOI) (%) UL-94 rating (3.2mm) Dry volume resistivity (Ω·cm) Volume resistivity (Ω·cm) after immersion in water for 24 hours Copper strip corrosion test results (100℃ / 168h) Example 1 36.5 V-0 <![CDATA[2.4×10 15 ]]> <![CDATA[9.5×10 14 ]]> No discoloration, glossy Example 2 38.2 V-0 <![CDATA[3.1×10 15 ]]> <![CDATA[1.2×10 15 ]]> No discoloration, glossy Example 3 40.4 V-0 <![CDATA[2.8×10 15 ]]> <![CDATA[8.6×10 14 ]]> No discoloration, glossy Comparative Example 1 31.5 V-1 <![CDATA[8.5×10 14 ]]> <![CDATA[4.2×10 12 ]]> Slight oxidation and darkening Comparative Example 2 35.8 V-0 <![CDATA[1.5×10 15 ]]> <![CDATA[6.3×10 12 ]]> No color change Comparative Example 3 37.9 V-0 <![CDATA[5.2×10 14 ]]> <![CDATA[2.4×10 11 ]]> The surface is severely blackened and pitted. Comparative Example 4 36.1 V-0 <![CDATA[2.1×10 15 ]]> <![CDATA[5.5×10 13 ]]> No color change Comparative Example 5 32.4 V-1 <![CDATA[9.2×10 14 ]]> <![CDATA[1.8×10 13 ]]> No color change

[0162] Conclusion Analysis:

[0163] According to the data in Table 4, the LOI values ​​of Examples 1-3 were 36.5%-40.4%, all reaching the UL-94V-0 rating, and the volume resistivity in both dry and wet states remained at 10. 15 -10 14 The corrosion resistance is on the order of Ω·cm, and no discoloration was observed in the copper sheet corrosion test. BDP promotes the dispersion of the flame retardant in the matrix, while the hydrotalcite adsorbs acidic ions, maintaining the insulation properties of the material.

[0164] Comparative Example 3 has a flame retardancy rating of V-0, but its volume resistivity drops to 10 after immersion in water. 11 The corrosion rate was on the order of Ω·cm, with blackening and pitting appearing on the copper sheet. The acetic acid produced by the decomposition of EVA was not neutralized, forming free conductive ions, which led to a decrease in insulation performance and corrosion of the metal conductor in humid environments.

[0165] The wet volume resistivity of Comparative Example 2 is 6.3 × 10⁻⁶. 12 The Ω·cm reading is significantly lower than in the previous example. The interfacial bonding relies on physical contact, resulting in insufficient density, allowing water molecules to penetrate along the phase boundary and form conductive channels.

[0166] The LOI of Comparative Example 5 decreased to 32.4%, with a rating of V-1. Premature reaction during processing led to poor material flowability, uneven dispersion of the flame retardant, and localized agglomeration, which reduced the flame retardant efficiency.

[0167] Test Example 4:

[0168] This test case aims to evaluate the anti-migration ability of liquid flame retardant (BDP) in the material and the retention of toughness at low temperatures. The stability of the interfacial solvation layer in the matrix is ​​verified through precipitation tests, and the low-temperature embrittlement temperature is used to verify the mitigation effect of the interfacial buffer layer on low-temperature stress concentration.

[0169] Experimental steps:

[0170] (1) The particles of Examples 1-3 and Comparative Examples 1-5 were prepared into square specimens of 50mm×50mm×2mm and Type A impact specimens conforming to the standard test method of ASTM D746 for determining the brittle temperature of plastics and elastomers.

[0171] (2) Weigh the initial mass of the square specimen. The sample was suspended in a 70℃ constant temperature forced-air drying oven for 168 hours. After cooling to room temperature, the surface was wiped with oil-absorbing paper to check for oil stains, and the mass was weighed again. ), calculate the quality loss rate.

[0172] (3) Low-temperature embrittlement impact test was conducted according to the standard test method for determining the brittle temperature of plastics and elastomers by impact method in ASTM D746. Ethanol was used as the heat transfer medium. Starting from -20℃, the temperature was gradually reduced in increments of 5℃. Ten specimens were tested at each temperature point, and the temperature at which the specimen breakage rate was 50% was recorded.

[0173] Experimental data:

[0174] Table 5. Test results of precipitation stability and low-temperature embrittlement properties

[0175] Group Mass loss rate (%) (70℃ / 168h) Surface precipitation observation Low-temperature embrittlement temperature (°C) Example 1 0.12 No oil stains, surface dry -42 Example 2 0.15 No oil stains, surface dry -45 Example 3 0.18 No oil stains, surface dry -43 Comparative Example 1 1.84 Noticeably oily, blotting paper is damp -24 Comparative Example 2 0.04 No oil stains -29 Comparative Example 3 0.22 No oil stains, surface slightly sticky -36 Comparative Example 4 0.16 No oil stains -38 Comparative Example 5 1.15 Oily spots in some areas -31

[0176] Conclusion Analysis:

[0177] According to the data in Table 5, the mass loss rate of Examples 1-3 was controlled at 0.12%-0.18%, with no surface precipitation and low-temperature embrittlement temperatures as low as -42℃ to -45℃. BDP was pre-coated onto the surface of the inorganic powder during the preparation process and was physically locked into the fixed interface layer through subsequent interfacial reactions, avoiding migration caused by the presence of free states. Simultaneously, the BDP liquid film at the interface provided stress buffering, hindering the nucleation of microcracks at the inorganic powder / matrix interface at low temperatures.

[0178] Comparative Example 5 showed a mass loss rate of 1.15%, with localized oil spots observed on the surface. Due to changes in the feeding sequence and process, BDP failed to preferentially wet the powder and was partially adsorbed by the resin matrix, failing to form an effective interfacial coating structure. This resulted in phase separation and migration to the surface during thermal aging.

[0179] Comparative Example 2 had a mass loss rate of 0.04% (no volatile components), but its embrittlement temperature was -29°C, significantly higher than that of the Example. The lack of a buffering effect from the interfacial solvation layer and the direct contact between the rigid powder and the matrix led to stress concentration, causing the material to exhibit brittle fracture under low-temperature impact.

[0180] The embrittlement temperature of Comparative Example 1 was -24℃. Due to the lack of interface toughening design and optimization of the compatibilizer system, the large amount of inorganic flame retardant filled in severely damaged the continuity of the matrix, resulting in the worst low-temperature toughness.

[0181] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A halogen-free flame-retardant polyolefin cable material, characterized in that, It is made from the following raw materials by reactive extrusion in parts by weight: Linear low-density polyethylene: 45.0-55.0 parts; Ethylene-vinyl acetate copolymer: 10.0-15.0 parts; Ethylene-methyl acrylate-glycidyl methacrylate terpolymer: 5.0-8.0 parts; Interface-solvent-modified flame-retardant powder: 39.5-53.0 parts; Active zinc oxide: 0.5-1.0 parts; Synthetic hydrotalcite: 0.3-0.6 parts; Antioxidant: 0.4-1.0 parts; Lubricant: 0.3-0.5 parts; The interface solvation modified flame retardant powder comprises aluminum diethylphosphinate, zinc anhydrous borate, and bisphenol A-bis(diphenyl phosphate) coated on the surfaces of aluminum diethylphosphinate and zinc anhydrous borate.

2. The halogen-free flame-retardant polyolefin cable material according to claim 1, characterized in that, The antioxidant is a compound of antioxidant 1010 and antioxidant 168; The lubricant is vinyl bis-stearamide.

3. The halogen-free flame-retardant polyolefin cable material according to claim 1, characterized in that, The interface-solvent-modified flame-retardant powder is made from the following raw materials in parts by weight: Aluminum diethylphosphinic acid: 35-45 parts; Anhydrous zinc borate: 3-5 parts; Liquid bisphenol A-bis(diphenyl phosphate): 1.5-3.0 parts; Furthermore, the interface solvation modified flame retardant powder is applied via an atomization spraying process to form a solvation liquid film of liquid bisphenol A-bis(diphenyl phosphate) on the surfaces of aluminum diethylphosphinate and anhydrous zinc borate.

4. The halogen-free flame-retardant polyolefin cable material according to claim 1, characterized in that, In the ethylene-methyl acrylate-glycidyl methacrylate terpolymer, the content of methyl acrylate is 20-30 wt%, and the content of glycidyl methacrylate is 2-8 wt%.

5. The halogen-free flame-retardant polyolefin cable material according to claim 1, characterized in that, The halogen-free flame-retardant polyolefin cable material has a multiphase structure, wherein the linear low-density polyethylene, ethylene-vinyl acetate copolymer and ethylene-methyl acrylate-glycidyl methacrylate terpolymer constitute a continuous phase matrix, the interface solvated modified flame-retardant powder is distributed as a dispersed phase in the continuous phase matrix, and the liquid bisphenol A-bis(diphenyl phosphate) is located in the interface layer between the dispersed phase and the continuous phase matrix.

6. A method for preparing halogen-free flame-retardant polyolefin cable material, characterized in that, The application of a halogen-free flame-retardant polyolefin cable material according to any one of claims 1-5 includes the following steps: Linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate terpolymer, active zinc oxide, synthetic hydrotalcite, antioxidant and lubricant are mixed evenly to obtain stabilized resin premix. Aluminum diethylphosphinic acid and anhydrous zinc borate were mixed and heated, and then atomized and sprayed into liquid bisphenol A-bis(diphenyl phosphate) under high-speed stirring. After cooling, dry and flowing interfacial solvation modified flame retardant powder was obtained. Reactive extrusion granulation is performed using a twin-screw extruder. The stabilized resin premix is ​​added to the main feed port of the twin-screw extruder, and the interface solvent-modified flame retardant powder is added to the side feed port of the twin-screw extruder. The mixture is then melted, reacted, extruded, air-cooled, and pelletized to obtain the halogen-free flame retardant polyolefin cable material.

7. The method for preparing a halogen-free flame-retardant polyolefin cable material according to claim 6, characterized in that, The specific preparation process of the interface solvation modified flame retardant powder is as follows: The aluminum diethylphosphonate and the anhydrous zinc borate are added to a mixer, and the heating jacket is turned on to raise the material temperature to 85-95°C. The material temperature is kept constant, and the liquid bisphenol A-bis(diphenyl phosphate) is uniformly sprayed into the mixer at a rate of 50-100 g / min through an atomizing nozzle at a stirring speed of 600-800 rpm. After spraying, the mixture is stirred at high speed for 5-8 minutes, and then the material is unloaded into a cooling mixer to cool to below 40°C.

8. The method for preparing a halogen-free flame-retardant polyolefin cable material according to claim 6, characterized in that, In the reactive extrusion granulation process: The length-to-diameter ratio of the twin-screw extruder used is 44:1-48:1; The side feed port is located at 20D-24D of the extruder.

9. The method for preparing a halogen-free flame-retardant polyolefin cable material according to claim 6, characterized in that, The temperature settings for each zone of the twin-screw extruder are as follows: Zones one through four are the melting and acid removal zones, with the temperature set at 160℃-175℃; Zones five through eight are the reaction and bonding sections, with the temperature set at 190℃-200℃; The section from zone nine to the machine head is the stable zone, with the temperature set at 165℃-175℃. The screw speed is set to 300-500 rpm.

10. A method for preparing a halogen-free flame-retardant polyolefin cable material according to claim 6, characterized in that, During the reactive extrusion granulation process, a vacuum treatment is performed in the stabilization section, and the vacuum degree is controlled between -0.06MPa and -0.09MPa.