Halogen-free high-flame-retardant cloth wire and preparation method thereof

Abstract

The application relates to the field of cloth electric wires, and discloses a halogen-free high-flame-retardant cloth electric wire and a preparation method thereof. The halogen-free high-flame-retardant cloth electric wire comprises a conductor, an insulation layer, a shielding layer and a sheath layer. The sheath layer material comprises linear low-density polyethylene, ethylene-vinyl acetate copolymer, modified hydrotalcite and an additive. The modified hydrotalcite is prepared by grafting a modified silane coupling agent and intercalated hydrotalcite. The modified silane coupling agent is prepared by reacting a triazine-based macromolecular charring agent and 3-isocyanate propyl trimethoxysilane. The triazine-based macromolecular charring agent is prepared by reacting a double-end amino phosphorus-containing intermediate and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. The double-end amino phosphorus-containing intermediate is prepared by reacting aminobenzene sulfone and phenyl phosphinic dichloride. The application adds the modified hydrotalcite to endow the material with good mechanical properties, long-term ultraviolet aging resistance and flame retardance.

Description

Technical Field

[0001] This invention belongs to the field of electrical wiring technology, specifically relating to a halogen-free, high flame-retardant electrical wiring and its preparation method. Background Technology

[0002] Insulated electrical wires, also known as building wires, mainly consist of three parts: a conductor, an insulation layer, and a sheath. They are suitable for various environments, including indoor and outdoor installations, and can be installed openly or concealed. They are generally used for power connections in lighting, power, and other equipment. The sheath of building electrical wires is usually made of specialized cable material. To prevent fires and reduce damage to the power system from fires, flame retardants are generally added to the cable material used to produce the sheath.

[0003] Inorganic flame retardants are frequently used flame retardants. However, in actual use, the addition of inorganic flame retardants can alter the physical, mechanical, and thermal properties of materials. Furthermore, these powders are prone to agglomeration, directly affecting the flame-retardant effect of inorganic filler particles. Agglomerated inorganic flame retardants can also significantly increase internal voids and defects in the material, leading to a decline in the overall mechanical properties. In addition, in intumescent flame retardant systems, the char source performance directly determines the quality and barrier effect of the char layer. Currently, commonly used char sources are mostly small-molecule charring agents, but they generally suffer from poor thermal stability, low flame-retardant efficiency, and insufficient compatibility, making it difficult for the char layer to form stably and easily weakening the mechanical and processing properties of composite materials.

[0004] In addition, the main reason for the failure of existing building wires is the failure of the sheath material, and the failure of the sheath material is mainly due to the influence of the external environment. Low-density polyethylene is a general-purpose plastic with a wide range of uses and is often used as the sheath material for building wires. However, its molecular structure is sensitive to ultraviolet light. Long-term exposure to ultraviolet light can easily cause oxidative degradation, leading to molecular chain breakage and cross-linking, which in turn leads to a significant decrease in mechanical properties and seriously limits the service life of the product. Summary of the Invention

[0005] To address the shortcomings mentioned in the background art, the present invention aims to provide a halogen-free high flame-retardant electrical wire and its preparation method. By adding modified hydrotalcite, the material is endowed with good mechanical properties, long-term UV aging resistance, and flame-retardant properties.

[0006] The objective of this invention can be achieved through the following technical solutions: A halogen-free, high flame-retardant electrical wire includes, from the inside out, a conductor, an insulation layer, a shielding layer, and a sheathing layer. The sheathing layer is prepared by extruding sheathing material outside the shielding layer using an extrusion device. The sheathing material comprises the following components by weight: 40-60 parts linear low-density polyethylene, 20-40 parts ethylene-vinyl acetate copolymer, 4-9 parts modified hydrotalcite, 0.2-0.5 parts plasticizer, 0.1-1 parts antioxidant, and 1-3 parts compatibilizer. The modified hydrotalcite is prepared by ion exchange of 4,4'-stilbene dicarboxylic acid to form an intercalated hydrotalcite, and by grafting a modified silane coupling agent prepared by nucleophilic addition reaction of triazine macromolecular char-forming agent and 3-isocyanate propyltrimethoxysilane onto the surface of the intercalated hydrotalcite. The triazine-based macromolecular char-forming agent is prepared by a nucleophilic substitution reaction using a phosphorus-containing intermediate with two amino terminals and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine as monomers; the phosphorus-containing intermediate with two amino terminals is prepared by a nucleophilic substitution reaction between sulfamic acid and phenylphosphonic dichloro; and the 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine is prepared by a nucleophilic substitution reaction between cyanuric chloride and ethanolamine.

[0007] Preferably, the plasticizer is one or a combination of several selected from dimethyl phthalate, dioctyl phthalate, and diisodecyl phthalate; the antioxidant is one or a combination of several selected from antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 1024; and the compatibilizer is one or a combination of two selected from maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene.

[0008] Preferably, the preparation method of the modified hydrotalcite includes the following steps: A. Take 4,4'-stilbene dicarboxylic acid, deionized water and anhydrous ethanol and stir evenly to obtain an intercalation solution. Take hydrotalcite, deionized water and anhydrous ethanol and ultrasonically disperse evenly at 65~75℃ to obtain a hydrotalcite dispersion. Then add the intercalation solution to the hydrotalcite dispersion, adjust the pH of the system to 4, and stir and reflux at 65~75℃ for 20~24h. After the reaction is completed, dry to constant weight to prepare intercalated hydrotalcite. B. Add triazine macromolecular char-forming agent and xylene to the reactor and stir until completely dissolved. While stirring, add 3-propyltrimethoxysilane and then stir the reaction at 35~45℃ for 3~4h to prepare the modified silane coupling agent. C. The intercalated hydrotalcite was ultrasonically dispersed in xylene, and then a modified silane coupling agent was added. The mixture was stirred continuously at 95~120℃ for 10~12h. After the reaction was completed, the modified hydrotalcite was obtained by centrifugation, washing and drying.

[0009] Preferably, the hydrotalcite in step A is magnesium aluminum carbonate type hydrotalcite; the mass ratio of 4,4'-stilbene dicarboxylic acid to hydrotalcite is 0.6~0.8:1.

[0010] Preferably, the preparation method of the triazine macromolecular char-forming agent in step B includes the following steps: B1. Add sulfamic acid and acetone to the reactor, and slowly add a mixed solution of phenylphosphonic dichloride and acetone under mechanical stirring. React in an ice-water bath for 3 hours. Add triethylamine in batches during the reaction. After the reaction is completed, filter to remove impurities, evaporate the solvent under reduced pressure, and prepare a phosphorus-containing intermediate with dual-terminated amino groups. B2. Add cyanuric chloride and acetone to the reactor, and add an aqueous solution of ethanolamine and sodium hydroxide dropwise under mechanical stirring. Control the pH value to 8-9, and react in an ice-water bath for 3 hours. After the reaction is completed, filter, wash and dry to prepare 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. B3. The phosphorus-containing intermediate with two amino terminals was added in two portions to a mixed solution of 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine and 1,4-dioxane. The reaction was first carried out at 55-65℃ for 4-5 hours, and then the temperature was raised to 95-105℃ for another 4-5 hours. Triethylamine was added in batches during the reaction. After the reaction was completed, the mixture was rotary evaporated, precipitated, washed and dried to prepare the triazine macromolecular char-forming agent.

[0011] Preferably, the molar ratio of sulfamic acid and phenylphosphonic dichloride in step B1 is 2:1.

[0012] Preferably, the molar ratio of cyanuric chloride and ethanolamine in step B2 is 1:1.

[0013] Preferably, in step B3, the molar ratio of the diamino-terminated phosphorus-containing intermediate and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine is 1:1 to 1.5.

[0014] Preferably, the preparation method of the sheath layer material includes the following steps: weighing each component according to the weight parts, melting and blending linear low-density polyethylene, ethylene-vinyl acetate copolymer and compatibilizer on a two-roll open mill, then adding modified hydrotalcite, plasticizer and antioxidant, continuing to mix evenly and then discharging, preheating at 165°C without pressure for 3 minutes on a flat vulcanizing machine, then pressing at 15MPa for 5 minutes to form the sheath layer material.

[0015] The preparation method of the halogen-free high flame-retardant electrical wire described above includes the following steps: S1. A cross-linked polyethylene insulation layer is extruded onto the outside of the conductor using an extruder; S2. A copper strip wrapping layer is wrapped around the outside of the insulation layer to form a shielding layer; S3. Use an extruder to coat the outer side of the shielding layer with the sheath material to prepare halogen-free high flame-retardant cloth wire.

[0016] The beneficial effects of this invention are: This invention utilizes a nucleophilic substitution reaction between sulfamic acid and phenylphosphonic dichloro to prepare a phosphorus-containing intermediate with dual amino groups. Simultaneously, it utilizes a nucleophilic substitution reaction between cyanuric chloride and ethanolamine to prepare 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. Then, using the dual amino-terminated phosphorus-containing intermediate and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine as monomers, a triazine-based macromolecular charring agent is prepared through a nucleophilic substitution reaction. This triazine-based macromolecular charring agent possesses a triazine ring skeleton, active hydroxyl functional groups, and aromatic phosphorus-sulfur units. This molecular structure not only improves the stability of the charring agent in the matrix material but also increases the charring efficiency of the flame-retardant system. Furthermore, this invention utilizes the organic anionic ultraviolet absorber 4,4'-stilbene dicarboxylic acid to remove some interlayer anionic carbonate (CO3-) from the inorganic filler hydrotalcite via ion exchange. 2- The process involves substitution to load 4,4'-stilbene dicarboxylic acid into the layered structure of hydrotalcite, resulting in intercalated hydrotalcite that acts as an anti-UV intercalation barrier agent, further enhancing the material's UV absorption capacity. The intercalated structure also imparts better stability to 4,4'-stilbene dicarboxylic acid within the hydrotalcite layers. Furthermore, the hydroxyl groups introduced from the triazine macromolecular charring agent undergo a nucleophilic addition reaction with 3-propyltrimethoxysilane to prepare a modified silane coupling agent. This modified silane coupling agent is then grafted onto the surface of the intercalated hydrotalcite using a chemical reaction, resulting in modified hydrotalcite. This improves the dispersion uniformity of hydrotalcite in the organic matrix, avoids stress concentration points caused by agglomeration, and is beneficial for improving... The material exhibits superior mechanical properties, and as an inorganic layered material, hydrotalcite possesses a certain ability to reflect and scatter ultraviolet rays (physical shielding). The 4,4'-stilbene dicarboxylic acid between the layers can absorb ultraviolet light, and the triazine ring introduced in the modified silane coupling agent also has a certain ultraviolet absorption capacity. The three work together to achieve a dual anti-ultraviolet mechanism of "reflection + absorption". In addition, since one end of the modified silane coupling agent forms a covalent bond with the hydroxyl group on the surface of hydrotalcite, and the other end is connected to the triazine macromolecular char-forming agent through a urethane bond, a stable chemical bridging structure is formed, achieving multifunctional synergy. Furthermore, it is not easy to debond or migrate during processing and use, thus ensuring the durability of ultraviolet aging resistance and flame retardant function and improving the service life of the material. Detailed Implementation

[0017] 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.

[0018] Example 1: A method for preparing a triazine-based macromolecular charforming agent includes the following steps: B1. Add 24.8g of sulfamic acid and 150mL of acetone to the reactor. Under mechanical stirring, slowly add a mixed solution of 9.7g of phenylphosphonic dichloride and 15mL of acetone. React in an ice-water bath for 3h. During the reaction, add 11.1g of triethylamine in batches. After the reaction is complete, filter to remove impurities and evaporate the solvent under reduced pressure to prepare a phosphorus-containing intermediate with dual-terminated amino groups. B2. Add 18.4g of cyanuric chloride and 150mL of acetone to the reactor. Add 6.1g of an aqueous solution of ethanolamine and sodium hydroxide dropwise under mechanical stirring. Control the pH value to 8. React in an ice-water bath for 3h. After the reaction is completed, filter, wash and dry to prepare 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. B3. 30.9 g of the diamino-terminated phosphorus-containing intermediate was added in two portions to a mixed solution of 10.5 g of 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine and 200 mL of 1,4-dioxane. The mixture was first reacted at 60 °C for 5 h, and then the temperature was raised to 100 °C and the reaction was continued for another 5 h. During the reaction, 5.6 g of triethylamine was added in batches. After the reaction was completed, the mixture was rotary evaporated, precipitated, washed, and dried to prepare a triazine-based macromolecular char-forming agent.

[0019] Example 2: A method for preparing modified hydrotalcite includes the following steps: A. Take 6.7g of 4,4'-stilbene dicarboxylic acid, 150mL of deionized water, and 150mL of anhydrous ethanol, and stir until homogeneous to obtain an intercalation solution. Take 10g of magnesium aluminum carbonate type hydrotalcite [Al2Mg6(OH)] 16 CO3·4H2O], 100 mL of deionized water and 100 mL of anhydrous ethanol were ultrasonically dispersed at 70 °C to obtain a hydrotalcite dispersion. Then, the intercalation solution was added to the hydrotalcite dispersion, the pH of the system was adjusted to 4, and the mixture was stirred and refluxed at 70 °C for 24 h. After the reaction was completed, the mixture was dried to constant weight to prepare the intercalated hydrotalcite. B. Add 20.9g of the triazine macromolecular char-forming agent prepared in Example 1 and 120mL of xylene to the reactor, stir until completely dissolved, add 4mL of 3-propyltrimethoxysilane while stirring, and then place the reactor at 40°C and stir for 4h to prepare the modified silane coupling agent. C. Take 5g of intercalated hydrotalcite and ultrasonically disperse it in 120mL of xylene. Then add 2.7g of modified silane coupling agent and stir continuously at 105℃ for 12h. After the reaction is completed, centrifuge, wash and dry to prepare modified hydrotalcite.

[0020] Example 3 A sheath layer material comprises the following components in parts by weight: 42 parts of linear low-density polyethylene (melt flow rate of 2.0 g / 10 min), 23 parts of ethylene-vinyl acetate copolymer (melt flow rate of 3.0 g / 10 min, VA content of 28%), 4.7 parts of modified hydrotalcite prepared in Example 2, 0.2 parts of plasticizer dimethyl phthalate, 0.2 parts of antioxidant 1010, and 1.1 parts of compatibilizer maleic anhydride grafted polyethylene.

[0021] The preparation method of the above-mentioned sheath layer material includes the following steps: weigh each component according to the weight parts, melt-blend linear low-density polyethylene, ethylene-vinyl acetate copolymer and compatibilizer on a two-roll mill, then add modified hydrotalcite, plasticizer and antioxidant, continue to mix evenly and discharge the material, the mixing temperature is 135℃, the mixing time is 20min, the rotation speed is 40r / min, preheat at 165℃ without pressure for 3min on a flat vulcanizing machine, then press at 15MPa for 5min to form the sheath layer material.

[0022] A method for preparing a halogen-free, high flame-retardant electrical wire includes the following steps: S1. A cross-linked polyethylene insulation layer is extruded onto the outside of the conductor using an extruder; S2. A copper strip wrapping layer is wrapped around the outside of the insulation layer to form a shielding layer; S3. Use an extruder to coat the outer side of the shielding layer with the sheath material to prepare halogen-free high flame-retardant cloth wire.

[0023] Example 4 A sheath layer material comprises the following components in parts by weight: 51 parts of linear low-density polyethylene (melt flow rate of 2.0 g / 10 min), 33 parts of ethylene-vinyl acetate copolymer (melt flow rate of 3.0 g / 10 min, VA content of 28%), 6.6 parts of modified hydrotalcite prepared in Example 2, 0.3 parts of plasticizer dimethyl phthalate, 0.5 parts of antioxidant 1010, and 1.8 parts of compatibilizer maleic anhydride grafted polyethylene.

[0024] The preparation method of the above-mentioned sheath layer material is the same as that in Example 3.

[0025] The preparation method of a halogen-free high flame-retardant fabric wire is the same as in Example 3.

[0026] Example 5 A sheath layer material comprises the following components in parts by weight: 58 parts of linear low-density polyethylene (melt flow rate of 2.0 g / 10 min), 39 parts of ethylene-vinyl acetate copolymer (melt flow rate of 3.0 g / 10 min, VA content of 28%), 8.8 parts of modified hydrotalcite prepared in Example 2, 0.4 parts of plasticizer dimethyl phthalate, 0.7 parts of antioxidant 1010, and 2.5 parts of compatibilizer maleic anhydride grafted polyethylene.

[0027] The preparation method of the above-mentioned sheath layer material is the same as that in Example 3.

[0028] The preparation method of a halogen-free high flame-retardant fabric wire is the same as in Example 3.

[0029] Comparative Example 1: A method for preparing a triazine-based macromolecular charforming agent includes the following steps: B1. Add 18.4g of cyanuric chloride and 150mL of acetone to the reactor. Add 6.1g of an aqueous solution of ethanolamine and sodium hydroxide dropwise under mechanical stirring. Control the pH value to 8. React in an ice-water bath for 3h. After the reaction is completed, filter, wash and dry to prepare 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. B2. 12.4 g of sulfamic acid was added in two portions to a mixed solution of 10.5 g of 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine and 200 mL of 1,4-dioxane. The mixture was first reacted at 60 °C for 5 h, and then the temperature was raised to 100 °C and the reaction was continued for another 5 h. During the reaction, 5.6 g of triethylamine was added in batches. After the reaction was completed, the mixture was rotary evaporated, precipitated, washed, and dried to prepare a triazine macromolecular char-forming agent.

[0030] Comparative Example 2: A method for preparing a modified hydrotalcite includes the following steps: A. Take 6.7g of 4,4'-stilbene dicarboxylic acid, 150mL of deionized water, and 150mL of anhydrous ethanol, and stir until homogeneous to obtain an intercalation solution. Take 10g of magnesium aluminum carbonate type hydrotalcite [Al2Mg6(OH)] 16 CO3·4H2O], 100 mL of deionized water and 100 mL of anhydrous ethanol were ultrasonically dispersed at 70 °C to obtain a hydrotalcite dispersion. Then, the intercalation solution was added to the hydrotalcite dispersion, the pH of the system was adjusted to 4, and the mixture was stirred and refluxed at 70 °C for 24 h. After the reaction was completed, the mixture was dried to constant weight to prepare the intercalated hydrotalcite. B. Add 20.9g of the triazine macromolecular char-forming agent prepared in Comparative Example 1 and 120mL of xylene to the reactor, stir until completely dissolved, add 4mL of 3-propyltrimethoxysilane while stirring, and then place the reactor at 40℃ and stir for 4h to prepare the modified silane coupling agent. C. Take 5g of intercalated hydrotalcite and ultrasonically disperse it in 120mL of xylene. Then add 2.7g of modified silane coupling agent and stir continuously at 105℃ for 12h. After the reaction is completed, centrifuge, wash and dry to prepare modified hydrotalcite.

[0031] Comparative Example 3: A method for preparing a modified hydrotalcite includes the following steps: A. Add 20.9g of the triazine macromolecular char-forming agent prepared in Example 1 and 120mL of xylene to the reactor, stir until completely dissolved, add 4mL of 3-propyltrimethoxysilane while stirring, and then place the reactor at 40℃ and stir for 4h to prepare the modified silane coupling agent. B. Take 5g of magnesium aluminum carbonate type hydrotalcite [Al2Mg6(OH)] 16 [CO3·4H2O] was ultrasonically dispersed in 120 mL of xylene, and then 2.7 g of modified silane coupling agent was added. The mixture was stirred continuously at 105 °C for 12 h. After the reaction was completed, the modified hydrotalcite was prepared by centrifugation, washing and drying.

[0032] Comparative Example 4: A sheathing material comprises the following components in parts by weight: 58 parts of linear low-density polyethylene (melt flow rate of 2.0 g / 10 min), 39 parts of ethylene-vinyl acetate copolymer (melt flow rate of 3.0 g / 10 min, VA content of 28%), 8.8 parts of modified hydrotalcite prepared in Comparative Example 2, 0.4 parts of plasticizer dimethyl phthalate, 0.7 parts of antioxidant 1010, and 2.5 parts of compatibilizer maleic anhydride grafted polyethylene.

[0033] The preparation method of the above-mentioned sheath layer material is the same as that in Example 3.

[0034] The preparation method of a halogen-free high flame-retardant fabric wire is the same as in Example 3.

[0035] Comparative Example 5: A sheathing material comprises the following components in parts by weight: 58 parts of linear low-density polyethylene (melt flow rate of 2.0 g / 10 min), 39 parts of ethylene-vinyl acetate copolymer (melt flow rate of 3.0 g / 10 min, VA content of 28%), 8.8 parts of modified hydrotalcite prepared in Comparative Example 3, 0.4 parts of plasticizer dimethyl phthalate, 0.7 parts of antioxidant 1010, and 2.5 parts of compatibilizer maleic anhydride grafted polyethylene.

[0036] The preparation method of the above-mentioned sheath layer material is the same as that in Example 3.

[0037] The preparation method of a halogen-free high flame-retardant fabric wire is the same as in Example 3.

[0038] Comparative Example 6: A sheathing material comprises the following components in parts by weight: 58 parts of linear low-density polyethylene (melt flow rate 2.0 g / 10 min), 39 parts of ethylene-vinyl acetate copolymer (melt flow rate 3.0 g / 10 min, VA content 28%), and magnesium aluminum carbonate type hydrotalcite [Al2Mg6(OH)]. 16 CO3·4H2O] 8.8 parts, plasticizer dimethyl phthalate 0.4 parts, antioxidant 1010 0.7 parts, compatibilizer maleic anhydride grafted polyethylene 2.5 parts.

[0039] The preparation method of the above-mentioned sheath layer material is the same as that in Example 3.

[0040] The preparation method of a halogen-free high flame-retardant fabric wire is the same as in Example 3.

[0041] Performance testing The performance of the sheathing materials prepared in Examples 3-5 and Comparative Examples 4-6 was tested: (1) Mechanical property testing: Tensile properties were tested using a universal mechanical testing machine in accordance with GB / T 1040.2-2022. The sample size was 100mm×5mm×3.5mm. The data results are shown in Table 1.

[0042] (2) UV aging resistance test: The sample was placed in a UV weathering test chamber of model HD-E802-4 for UV aging resistance test. Aging conditions: temperature 50℃, light intensity 1W / m 2 Tensile strength and tensile strength retention rate were tested after UV aging for 10 days and 20 days. The data results are shown in Table 1.

[0043] (3) Limiting oxygen index test: The HC-2 oxygen index meter was used to test according to GB / T 2406.2-2009 standard. The sample size was 120mm×6.5mm×3mm. The data results are shown in Table 1.

[0044] (4) UL-94 test: The test was conducted using a 5402 horizontal and vertical combustion tester in accordance with the GB / T 2408-2021 standard. The sample size was 125mm×13mm×3mm. The data results are shown in Table 1.

[0045] Table 1 Sample performance test results

[0046] As can be seen from the data results in Table 1, the sheath layer materials prepared in Examples 3-5 of the present invention have good mechanical properties, long-term UV aging resistance and flame retardant properties. In Comparative Example 4, the modified hydrotalcite was prepared by replacing the bi-amino-terminated phosphorus intermediate with an equimolar amount of aminophenyl sulfone. Its flame retardant performance was lower than that of Examples 3-5, indicating that the introduction of phosphorus can improve the flame retardant performance of the material to a certain extent. In Comparative Example 5, the modified hydrotalcite was prepared without the introduction of 4,4'-stilbene dicarboxylic acid for intercalation. Its tensile strength retention rate after aging was lower than that of Examples 3-5. This is because the formed intercalation structure can impart better stability to 4,4'-stilbene dicarboxylic acid in the hydrotalcite layers, enhancing the material's UV absorption capacity and long-term stability. In Comparative Example 6, no modification was performed on the hydrotalcite. Its tensile strength, elongation at break, tensile strength retention rate after aging, limiting oxygen index, and UL-94 were significantly lower than those of Examples 3-5, indicating that modification of the hydrotalcite can greatly improve the material's mechanical properties, long-term UV aging resistance, and flame retardant performance.

[0047] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A halogen-free, high flame-retardant electrical wire, characterized in that, The material comprises, from the inside out, a conductor, an insulating layer, a shielding layer, and a sheathing layer. The sheathing layer is prepared by extruding sheathing material from the outside of the shielding layer using an extrusion device. The sheathing material comprises the following components by weight: 40-60 parts of linear low-density polyethylene, 20-40 parts of ethylene-vinyl acetate copolymer, 4-9 parts of modified hydrotalcite, 0.2-0.5 parts of plasticizer, 0.1-1 parts of antioxidant, and 1-3 parts of compatibilizer. The modified hydrotalcite is prepared by ion exchange of 4,4'-stilbene dicarboxylic acid to form an intercalated hydrotalcite, and by grafting a modified silane coupling agent prepared by nucleophilic addition reaction of triazine macromolecular char-forming agent and 3-isocyanate propyltrimethoxysilane onto the surface of the intercalated hydrotalcite. The triazine-based macromolecular char-forming agent is prepared by a nucleophilic substitution reaction using a phosphorus-containing intermediate with two amino terminals and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine as monomers; the phosphorus-containing intermediate with two amino terminals is prepared by a nucleophilic substitution reaction between sulfamic acid and phenylphosphonic dichloro; and the 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine is prepared by a nucleophilic substitution reaction between cyanuric chloride and ethanolamine.

2. The halogen-free high flame-retardant electrical wire according to claim 1, characterized in that, The plasticizer is one or a combination of several of dimethyl phthalate, dioctyl phthalate, and diisodecyl phthalate; the antioxidant is one or a combination of several of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 1024; and the compatibilizer is one or a combination of two of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene.

3. The halogen-free high flame-retardant electrical wire according to claim 1, characterized in that, The preparation method of the modified hydrotalcite includes the following steps: A. Take 4,4'-stilbene dicarboxylic acid, deionized water and anhydrous ethanol and stir evenly to obtain an intercalation solution. Take hydrotalcite, deionized water and anhydrous ethanol and ultrasonically disperse evenly at 65~75℃ to obtain a hydrotalcite dispersion. Then add the intercalation solution to the hydrotalcite dispersion, adjust the pH of the system to 4, and stir and reflux at 65~75℃ for 20~24h. After the reaction is completed, dry to constant weight to prepare intercalated hydrotalcite. B. Add triazine macromolecular char-forming agent and xylene to the reactor and stir until completely dissolved. While stirring, add 3-propyltrimethoxysilane and then stir the reaction at 35~45℃ for 3~4h to prepare the modified silane coupling agent. C. The intercalated hydrotalcite was ultrasonically dispersed in xylene, and then a modified silane coupling agent was added. The mixture was stirred continuously at 95~120℃ for 10~12h. After the reaction was completed, the modified hydrotalcite was obtained by centrifugation, washing and drying.

4. The halogen-free high flame-retardant electrical wire according to claim 3, characterized in that, In step A, the hydrotalcite is magnesium aluminum carbonate type hydrotalcite; the mass ratio of 4,4'-stilbene dicarboxylic acid to hydrotalcite is 0.6~0.8:

1.

5. The halogen-free high flame-retardant electrical wire according to claim 3, characterized in that, The preparation method of the triazine macromolecular charring agent in step B includes the following steps: B1. Add sulfamic acid and acetone to the reactor, and slowly add a mixed solution of phenylphosphonic dichloride and acetone under mechanical stirring. React in an ice-water bath for 3 hours. Add triethylamine in batches during the reaction. After the reaction is completed, filter to remove impurities, evaporate the solvent under reduced pressure, and prepare a phosphorus-containing intermediate with dual-terminated amino groups. B2. Add cyanuric chloride and acetone to the reactor, and add an aqueous solution of ethanolamine and sodium hydroxide dropwise under mechanical stirring. Control the pH value to 8-9, and react in an ice-water bath for 3 hours. After the reaction is completed, filter, wash and dry to prepare 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine. B3. The phosphorus-containing intermediate with two amino terminals was added in two portions to a mixed solution of 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine and 1,4-dioxane. The reaction was first carried out at 55-65℃ for 4-5 hours, and then the temperature was raised to 95-105℃ for another 4-5 hours. Triethylamine was added in batches during the reaction. After the reaction was completed, the mixture was rotary evaporated, precipitated, washed and dried to prepare the triazine macromolecular char-forming agent.

6. The halogen-free high flame-retardant electrical wire according to claim 5, characterized in that, In step B1, the molar ratio of sulfamic acid and phenylphosphonic dichloride is 2:

1.

7. The halogen-free high flame-retardant electrical wire according to claim 5, characterized in that, In step B2, the molar ratio of cyanuric chloride to ethanolamine is 1:

1.

8. The halogen-free high flame-retardant electrical wire according to claim 5, characterized in that, In step B3, the molar ratio of the diamino-terminated phosphorus intermediate and 2-(2-hydroxyethylamino)-4,6-dichloro-1,3,5-triazine is 1:1 to 1.

5.

9. The halogen-free high flame-retardant electrical wire according to claim 1, characterized in that, The preparation method of the sheath layer material includes the following steps: weigh each component according to the weight parts, melt-blend linear low-density polyethylene, ethylene-vinyl acetate copolymer and compatibilizer on a two-roll open mill, then add modified hydrotalcite, plasticizer and antioxidant, continue to mix evenly and discharge the material, preheat it at 165°C without pressure for 3 minutes on a flat vulcanizing machine, then press it to 15MPa for 5 minutes to form the sheath layer material.

10. A method for preparing a halogen-free high flame-retardant electrical wire according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. A cross-linked polyethylene insulation layer is extruded onto the outside of the conductor using an extruder; S2. A copper strip wrapping layer is wrapped around the outside of the insulation layer to form a shielding layer; S3. Use an extruder to coat the outer side of the shielding layer with the sheath material to prepare halogen-free high flame-retardant cloth wire.

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