Flame-retardant high-temperature-resistant power cable material and preparation method thereof

Abstract

The application discloses a kind of flame-retardant high-temperature-resistant power cable materials and preparation method thereof, belong to power cable material preparation field, mainly aiming at the technical problem that the high-temperature-resistant performance and flame-retardant performance of power cable material need to be further improved, specifically includes the conductive wire core, inner lining, armoring layer and outer sheath layer sequentially arranged from inside to outside, outer sheath layer is obtained by flame-retardant high-temperature-resistant material melt extrusion in the armoring layer outside.This application is with polyether type thermoplastic polyurethane as matrix, by silanization grafting and metal, polyphenol coordination network cover hollow glass microsphere preparation hybrid microbead, and siloxane chain segment is embedded into benzoxazine skeleton by mannich condensation and is prepared modified resin, after two things blend extrusion and form, it is crosslinked by high temperature and forms semi-interpenetrating network, synergistically improves the flame-retardant and high-temperature-resistant performance of power cable material.

Description

Technical Field

[0001] This invention relates to the field of power cable material preparation, specifically to a flame-retardant and high-temperature resistant power cable material and its preparation method. Background Technology

[0002] With the continuous expansion of high-voltage power transmission networks and the rapid growth of new energy grid connection, the outer sheath material of power cables must simultaneously meet the requirements of flame retardancy and high temperature resistance. Under the action of overload or external fire source, the sheath material must have the property of charring. Under the combined effect of long-term current carrying and heating and environmental temperature change, it must maintain high-temperature morphological stability and mechanical integrity. However, the flame retardancy and high temperature resistance of the sheath material often hinder each other. How to achieve synergistic improvement in the same system has always been the core technical problem in the field of cable materials.

[0003] The main materials for power cable sheaths include cross-linked polyethylene, ethylene propylene rubber, and thermoplastic polyurethane elastomers. Common modification methods include: adding metal hydroxides to inhibit combustion by utilizing the heat absorption of dehydration; using phosphorus and nitrogen synergistic expansion flame retardant systems to form a carbon layer in the condensed phase; and improving high-temperature dimensional stability through irradiation or chemical cross-linking. However, the above methods have certain limitations in practical applications, which restrict the further improvement of the overall performance of sheath materials.

[0004] Currently, lightweight functional fillers such as hollow microspheres have weak interfacial bonding with polymer matrices. Without effective surface modification, they are prone to forming stress concentration zones at the interface, which become the starting point for material failure under high temperature and dynamic loads. Furthermore, the condensed phase char layer structure formed by conventional flame retardant systems is loose and has limited thermal stability. Under continuous thermal oxidation, the char layer is easily broken and falls off, resulting in a significant decrease in the effectiveness of the thermal insulation barrier. At the same time, traditional high-temperature thermosetting components are highly brittle after curing, and when combined with the elastomer matrix, the interfacial stress is concentrated, making them prone to interfacial debonding and cracking under thermal shock cyclic loading.

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

[0006] The purpose of this invention is to provide a flame-retardant and high-temperature resistant power cable material and its preparation method, in order to solve the technical problem that the high-temperature resistance and flame-retardant properties of existing power cable materials need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a flame-retardant and high-temperature resistant power cable material, comprising a conductive core, an inner lining layer, an armor layer and an outer sheath layer arranged sequentially from the inside to the outside, wherein the conductive core comprises four parallel cable cores and insulating rubber, filler and wrapping tape covering the outside of the cable cores, and the outer sheath layer is obtained by melting and extruding flame-retardant and high-temperature resistant material on the outside of the armor layer; The flame-retardant and high-temperature resistant material comprises the following components by weight: 80-100 parts of polyether-type thermoplastic polyurethane elastomer, 15-25 parts of siloxane-modified benzoxazine resin, 10-15 parts of hybrid microspheres and 1-3 parts of auxiliary materials. The siloxane-modified benzoxazine resin was prepared by the following steps: A1. Tetramethyltetraphenylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and toluene were placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel was heated to 100-110℃, tetramethylammonium hydroxide was added, and the reaction was maintained at this temperature for 4-6 hours. The reaction vessel was then heated to 145-155℃ and the reaction was maintained at this temperature for 1-2 hours. The post-treatment yielded amino-terminated polymethylphenylsiloxane. A2. Place paraformaldehyde in a reaction vessel and stir. Heat the reaction vessel to 40-50℃, add 2,2-bis(4'-hydroxyphenyl)propane and toluene, stir for 10-15 min, add amino-terminated polymethylphenylsiloxane, heat the reaction vessel to 75-85℃, and keep the reaction at this temperature for 4-6 h. Post-treatment yields siloxane-modified benzoxazine resin.

[0008] The reaction formula for preparing siloxane-modified benzoxazine resin is as follows:

[0009] Further, in step A1, the ratio of tetramethyltetraphenylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, toluene, and tetramethylammonium hydroxide is 3-5g:1.2-1.6g:10-12mL:0.01-0.03g. The post-processing step includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 90-100℃, and evaporated under reduced pressure until no liquid is collected, to obtain amino-terminated polymethylphenylsiloxane.

[0010] Further, in step A2, the ratio of paraformaldehyde, 2,2-bis(4'-hydroxyphenyl)propane, toluene, and amino-terminated polymethylphenylsiloxane is 0.1-0.3g:0.4-0.6g:8-10mL:1.5-2.0g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, the reaction solution is washed with saturated saline and deionized water until neutral, dried with anhydrous sodium sulfate, and then transferred to a rotary evaporator at a temperature of 90-100℃. The evaporation is carried out under reduced pressure until no liquid is collected, thus obtaining siloxane-modified benzoxazine resin.

[0011] Furthermore, the hybrid microspheres are prepared by the following steps: B1. Hollow glass microspheres, deionized water and ethanol are placed in a reaction vessel and stirred. 3-aminopropyltriethoxysilane is added. The reaction vessel is heated to 55-65℃ and kept at this temperature for 3-5 hours. After post-treatment, aminated hollow glass microspheres are obtained. B2. Place aminated hollow glass microspheres and deionized water in a reaction vessel and stir. Add tannic acid and stir for 25-35 minutes. Add ferric chloride hexahydrate aqueous solution and stir at room temperature for 1-2 hours. Post-treatment yields hybrid microspheres.

[0012] Further, in step B1, the ratio of the hollow glass microspheres, deionized water, ethanol, and 3-aminopropyltriethoxysilane is 1-2g:4-6mL:17-19mL:0.5-0.7g. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain aminated hollow glass microspheres.

[0013] Further, in step B2, the ratio of the amination-modified hollow glass microspheres, deionized water, tannic acid, and ferric chloride hexahydrate aqueous solution is 2-4g:20-25mL:0.4-0.6g:5-7mL. The ferric chloride hexahydrate aqueous solution is obtained by uniformly mixing ferric chloride hexahydrate and deionized water at a ratio of 1g:20mL. The post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed with deionized water 2-4 times, and then transferred to an oven at a temperature of 60-70℃ to dry for 10-12 hours to obtain hybrid microspheres.

[0014] This invention also proposes a method for preparing a flame-retardant and high-temperature resistant power cable material, comprising the following steps: S1. Add polyether-type thermoplastic polyurethane elastomer, siloxane-modified benzoxazine resin, hybrid microspheres and excipients into a high-speed homogenizer and stir evenly at room temperature to obtain a premix. S2. The premixed material is added to a twin-screw extruder for melt mixing, pelletized and dried to obtain a flame-retardant and high-temperature resistant material; S3. The four parallel cable cores are wrapped with insulating rubber and filler in sequence and tied with wrapping tape to form conductive cores. Inner lining material is extruded on the outside of the conductive cores to form an inner lining layer. Multiple galvanized round steel wires are tightly wrapped in a single spiral along the outer periphery of the inner lining layer with constant tension on the armoring machine to form an armor layer. S4. Add flame-retardant and high-temperature resistant material into a single-screw extruder and melt-extrude it onto the outside of the armor layer at a temperature of 150-170℃ to form an outer sheath layer; S5. The cable is fed into a continuous hot air circulating tunnel furnace and subjected to heat treatment at 180-200℃. After cooling the coil, flame-retardant and high-temperature resistant power cable material is obtained.

[0015] Further, in step S1, the excipients are composed of antioxidants, lubricants, silane coupling agents, and hydrolytic stabilizers in a mass ratio of 4:1:1:2. The antioxidants are one or more of N,N'-diphenyl-p-phenylenediamine, tris(2,4-di-tert-butylphenyl) phosphite, and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The lubricants are one or more of fatty acid amides, oleamides, and paraffin wax. The silane coupling agents are one or more of 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. The hydrolytic stabilizers are one or more of N,N'-di(2,6-diisopropylphenyl)carbodiimide, epoxidized soybean oil, and 2-phenyl-2-oxazoline.

[0016] Furthermore, in step S2, the temperature of each section of the twin-screw extruder is set to 160-190℃, the screw speed is 200-400rpm, and after pelleting, it is dried at 80-90℃ for 4-6 hours.

[0017] Furthermore, in step S3, the insulating rubber is ethylene propylene rubber or silicone rubber, the filler is polypropylene rope or alkali-free glass fiber rope, the wrapping tape is polyester film tape or flame-retardant non-woven fabric tape, the inner lining material is chlorinated polyethylene, the extrusion temperature is 140-160℃, the inner lining thickness is 1.0-2.0mm, the diameter of the galvanized round steel wire is 0.8-1.2mm, and the wrapping pitch is 40-60mm.

[0018] Furthermore, in step S4, the temperatures of the single-screw extruder from the feeding section to the die head are set sequentially to 140℃, 155℃, 165℃, and 170℃, the screw speed is 30-60 rpm, and the outer sheath layer thickness is 2.0-3.5 mm.

[0019] Furthermore, in step S5, the cable is kept warm in the continuous hot air circulating tunnel furnace for 30-60 minutes, the traction speed is 3-6 m / min, and the cooling coil is cooled by circulating water with a cooling water temperature of 15-25℃.

[0020] The present invention has the following beneficial effects: This invention involves sequentially constructing a silanized graft layer and a metal-polyphenol coordination complex layer on the surface of hollow glass microspheres to form a bifunctional hybrid interface. The silanized layer covalently anchors the microspheres and the polyurethane matrix, eliminating interfacial slip defects. During combustion, the metal and polyphenol layers, through the catalytic effects of polyphenol char promotion and ferric ions, form a dense, heat-insulating char layer in the condensed phase, effectively cutting off heat and mass transfer channels. The two modified structures reinforce each other, achieving a synergistic effect of interfacial mechanical compatibilization and condensed phase flame retardancy. The flame retardant and high-temperature resistance properties of the material system are significantly improved.

[0021] This invention further incorporates amino-terminated polymethylphenylsiloxane into the benzoxazine ring backbone via Mannich condensation, allowing flexible Si-O-Si segments to be distributed between cross-linked network nodes in the form of chemical bonds. The high bond energy Si-O backbone endows the cured network with intrinsic thermo-oxidative stability, while the steric hindrance of the phenyl side chains further hinders thermo-oxidative degradation. At the same time, the flexible segments effectively disperse the strain energy required for crack propagation, overcoming the inherent defect of high brittleness in conventional benzoxazine cured products and achieving a synergistic improvement in the heat resistance and toughness of the material system.

[0022] The flame-retardant and high-temperature resistant power cable material prepared by this invention, after high-temperature heat treatment, forms a three-dimensional covalent network by siloxane-modified benzoxazine ring-opening crosslinking, which interpenetrates with the polyether-type polyurethane molecular chain to construct a semi-interpenetrating network structure. Hybrid microspheres are chemically anchored at the interface nodes of this network. The crosslinked network restricts the high-temperature creep of polyurethane, the hybrid microspheres strengthen the burning char layer and inhibit melt dripping, and the siloxane segments give the overall network a high-temperature toughness margin, which together improves the heat resistance and flame-retardant properties of the material system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall cross-sectional structure of the present invention.

[0025] In the diagram: 1. Conductive core; 1-1. Cable core; 1-2. Insulating rubber; 1-3. Filler; 1-4. Wrapping tape; 2. Inner lining layer; 3. Armor layer; 4. Outer sheath layer. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The commercially available bisphenol A type benzoxazine resin used in this invention was purchased from Hubei Shuaiyan Ligao Biomedical Co., Ltd., and its appearance is a light yellow to brown powder with a softening point of 60-80℃. The polyether-type thermoplastic polyurethane elastomer used in this invention was purchased from Suzhou Tiantao Plastics Co., Ltd., brand name Lubrizol, USA, product number AG 8451-E; The paraformaldehyde used in this invention was purchased from Jinan Jiewei Chemical Technology Co., Ltd., and it is a white powder with a degree of polymerization of 8-20. The hollow glass microspheres used in this invention were purchased from Hebei Houkang Mineral Products Co., Ltd., and have a density of 0.35±0.03 g / cm³. 3 The sphericity is 98.3%. Example

[0028] This embodiment provides a method for preparing hybrid microspheres, including the following steps: Step I: Preparation of Aminated Hollow Glass Microspheres Weigh 10g of hollow glass microspheres, 40mL of deionized water and 170mL of ethanol and place them in a reaction vessel and stir. Add 5g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 55℃ and keep it at that temperature for 3h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃ and dry it to constant weight to obtain aminated hollow glass microspheres.

[0029] Step II: Preparation of hybrid microbeads Mix ferric chloride hexahydrate and deionized water at a ratio of 10g:200mL to obtain an aqueous solution of ferric chloride hexahydrate for later use. Weigh 20g of aminated hollow glass microspheres and 200mL of deionized water and place them in a reaction vessel and stir. Add 4g of tannic acid and stir for 25min. Add 50mL of ferric chloride hexahydrate aqueous solution and stir at room temperature for 1h. After the reaction is complete, filter the mixture and wash the filter cake twice with deionized water. Transfer the cake to an oven at 60℃ and dry for 10h to obtain hybrid microspheres.

[0030] 3-Aminopropyltriethoxysilane hydrolyzes in a water / ethanol system to generate silanol groups, which undergo dehydration condensation with the silanol groups on the surface of hollow glass microspheres to form siloxane covalent bonds. Aminopropyl groups are then covalently grafted onto the surface of the microspheres to obtain aminated hollow glass microspheres. Tannic acid is further adsorbed onto the surface of the aminated microspheres via hydrogen bonding and electrostatic interactions. After the introduction of ferric chloride hexahydrate, ferric ions coordinate with the polyphenolic groups of tannic acid to form a complex, constructing a metal-polyphenol coordination network on the surface of the microspheres and forming an organic-inorganic composite coating layer to obtain hybrid microspheres.

[0031] The silanization reaction covalently grafts aminopropyl functional groups onto the surface of hollow glass microspheres, providing chemical anchoring sites for the subsequent directional assembly of metal and polyphenol networks. It also significantly improves the interfacial bonding strength between the hybrid microsphere filler and the polymer matrix, suppressing interfacial debonding failure under thermal stress. The metal-polyphenol coordination network constructed by tannic acid and ferric ions on the surface of the microspheres forms a polyphenol-iron-rich organic-inorganic composite coating. During thermal degradation, the polyphenol groups promote char formation, and the ferric ions catalyze the densification of the char layer. The two work synergistically to enhance the flame retardant properties and high-temperature dimensional stability of the power cable material. Example

[0032] This embodiment provides a method for preparing hybrid microspheres, including the following steps: Step I: Preparation of Aminated Hollow Glass Microspheres Weigh 15g of hollow glass microspheres, 50mL of deionized water and 180mL of ethanol and place them in a reaction vessel and stir. Add 6g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 60℃ and keep it at that temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 55℃ and dry it to constant weight to obtain aminated hollow glass microspheres.

[0033] Step II: Preparation of hybrid microbeads Mix ferric chloride hexahydrate and deionized water at a ratio of 10g:200mL to obtain an aqueous solution of ferric chloride hexahydrate for later use. Weigh 30g of amination-modified hollow glass microspheres and 225mL of deionized water and place them in a reaction vessel and stir. Add 5g of tannic acid and stir for 30min. Add 60mL of ferric chloride hexahydrate aqueous solution and stir at room temperature for 1.5h. After the reaction is complete, filter the mixture and wash the filter cake three times with deionized water. Transfer the cake to an oven at 65℃ and dry for 11h to obtain hybrid microspheres. Example

[0034] This embodiment provides a method for preparing hybrid microspheres, including the following steps: Step I: Preparation of Aminated Hollow Glass Microspheres Weigh 20g of hollow glass microspheres, 60mL of deionized water and 190mL of ethanol and place them in a reaction vessel and stir. Add 7g of 3-aminopropyltriethoxysilane, heat the reaction vessel to 65℃ and keep it at that temperature for 5h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the filter cake 4 times with deionized water and ethanol, transfer it to an oven at 60℃ and dry it to constant weight to obtain aminated hollow glass microspheres.

[0035] Step II: Preparation of hybrid microbeads Mix ferric chloride hexahydrate and deionized water at a ratio of 10g:200mL to obtain an aqueous solution of ferric chloride hexahydrate for later use. Weigh 40g of amination-modified hollow glass microspheres and 250mL of deionized water and place them in a reaction vessel and stir. Add 6g of tannic acid and stir for 35min. Add 70mL of ferric chloride hexahydrate aqueous solution and stir at room temperature for 2h. After the reaction is complete, filter the mixture and wash the filter cake 4 times with deionized water. Transfer the cake to an oven at 70℃ and dry for 12h to obtain hybrid microspheres. Example

[0036] This embodiment provides a method for preparing a siloxane-modified benzoxazine resin, comprising the following steps: Step ①: Preparation of amino-terminated polymethylphenylsiloxane Weigh out 30g of tetramethyltetraphenylcyclotetrasiloxane, 12g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and 100mL of toluene and place them in a reaction vessel under nitrogen atmosphere. Stir the mixture and heat the reaction vessel to 100℃. Add 0.1g of tetramethylammonium hydroxide and maintain the temperature for 4h. Then heat the reaction vessel to 145℃ and maintain the temperature for 1h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator at 90℃. Evaporate under reduced pressure until no liquid is collected to obtain amino-terminated polymethylphenylsiloxane.

[0037] Step 2: Preparation of siloxane-modified benzoxazine resin Weigh 1g of paraformaldehyde and place it in a reaction vessel and stir. Heat the reaction vessel to 40℃, add 4g of 2,2-bis(4'-hydroxyphenyl)propane and 80mL of toluene, stir for 10min, add 15g of terminal amino-terminated polymethylphenylsiloxane, heat the reaction vessel to 75℃, and keep the reaction at this temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, wash the reaction solution with saturated saline and deionized water until neutral, dry it with anhydrous sodium sulfate, and transfer it to a rotary evaporator at 90℃. Evaporate under reduced pressure until no liquid is collected to obtain siloxane-modified benzoxazine resin.

[0038] Tetramethyltetraphenylcyclotetrasiloxane undergoes anionic ring-opening polymerization under catalysis. 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is used as a capping agent to introduce terminal amino groups and control the polymerization chain length. The polymerization is terminated by heating until the catalyst is thermally deactivated, yielding amino-terminated polymethylphenylsiloxane. Further, the primary amino groups of the amino-terminated polymethylphenylsiloxane undergo Mannich condensation reaction with formaldehyde released in situ from paraformaldehyde and the phenolic hydroxyl groups of 2,2-bis(4'-hydroxyphenyl)propane to form a benzoxazine six-membered heterocyclic structure. Flexible siloxane segments are covalently embedded into the benzoxazine resin molecular chain to obtain siloxane-modified benzoxazine resin.

[0039] The polymethylphenylsiloxane backbone constructed by anionic ring-opening polymerization has a high-bond-energy Si-O backbone and side-attached phenyl groups. The former endows the material with intrinsic thermo-oxidative stability, while the latter promotes the formation of aromatic char layers during thermal degradation. The precise introduction of terminal amino groups provides directional reactive sites for subsequent covalent assembly. The benzoxazine heterocyclic structure formed by Mannich condensation ring closure produces a high char rate during thermal decomposition, effectively blocking heat transfer and the escape of combustible volatiles. Flexible siloxane segments are covalently embedded in the benzoxazine backbone, reducing the brittleness of the cured product and improving the dimensional stability and mechanical integrity of the outer sheath under thermal shock conditions, thus achieving synergistic enhancement of flame retardancy and high-temperature resistance. Example

[0040] This embodiment provides a method for preparing a siloxane-modified benzoxazine resin, comprising the following steps: Step ①: Preparation of amino-terminated polymethylphenylsiloxane Weigh out 40g of tetramethyltetraphenylcyclotetrasiloxane, 14g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and 110mL of toluene and place them in a reaction vessel under nitrogen atmosphere. Stir the mixture and heat the reaction vessel to 105℃. Add 0.2g of tetramethylammonium hydroxide and maintain the temperature for 5h. Then heat the reaction vessel to 150℃ and maintain the temperature for 1.5h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator at 95℃. Evaporate under reduced pressure until no liquid is collected to obtain amino-terminated polymethylphenylsiloxane.

[0041] Step 2: Preparation of siloxane-modified benzoxazine resin Weigh 2g of paraformaldehyde and place it in a reaction vessel and stir. Heat the reaction vessel to 45℃, add 5g of 2,2-bis(4'-hydroxyphenyl)propane and 90mL of toluene, stir for 13min, add 17.5g of amino-terminated polymethylphenylsiloxane, heat the reaction vessel to 80℃, and keep the reaction at this temperature for 5h. After the reaction is complete, wait for the reaction system to cool to room temperature, wash the reaction solution with saturated saline and deionized water until neutral, dry it with anhydrous sodium sulfate, and transfer it to a rotary evaporator at 95℃. Evaporate under reduced pressure until no liquid is collected to obtain siloxane-modified benzoxazine resin. Example

[0042] This embodiment provides a method for preparing a siloxane-modified benzoxazine resin, comprising the following steps: Step ①: Preparation of amino-terminated polymethylphenylsiloxane Weigh out 50g of tetramethyltetraphenylcyclotetrasiloxane, 16g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and 120mL of toluene and place them in a reaction vessel under nitrogen atmosphere. Stir the mixture and heat the reaction vessel to 110℃. Add 0.3g of tetramethylammonium hydroxide and maintain the temperature for 6h. Then heat the reaction vessel to 155℃ and maintain the temperature for 2h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator at 100℃. Evaporate under reduced pressure until no liquid is collected to obtain amino-terminated polymethylphenylsiloxane.

[0043] Step 2: Preparation of siloxane-modified benzoxazine resin Weigh 3g of paraformaldehyde and place it in a reaction vessel and stir. Heat the reaction vessel to 50℃, add 6g of 2,2-bis(4'-hydroxyphenyl)propane and 100mL of toluene, stir for 15min, add 20g of terminal amino-terminated polymethylphenylsiloxane, heat the reaction vessel to 85℃, and keep the reaction at this temperature for 6h. After the reaction is complete, wait for the reaction system to cool to room temperature, wash the reaction solution with saturated saline and deionized water until neutral, dry it with anhydrous sodium sulfate, and transfer it to a rotary evaporator at 100℃. Evaporate under reduced pressure until no liquid is collected to obtain siloxane-modified benzoxazine resin. Example

[0044] This embodiment provides a method for preparing a flame-retardant and high-temperature resistant power cable material, including the following steps: Step 1: Preparation of premix N,N'-diphenyl-p-phenylenediamine, fatty acid amide, 3-aminopropyltriethoxysilane and N,N'-bis(2,6-diisopropylphenyl)carbodiimide were mixed evenly in a mass ratio of 4:1:1:2 to obtain the excipient, which was then set aside. Weigh out the following by weight: 80 parts of polyether-type thermoplastic polyurethane elastomer, 15 parts of siloxane-modified benzoxazine resin prepared in Example 4, 10 parts of hybrid microspheres prepared in Example 1, and 1 part of excipients. Add them to a high-speed homogenizer and stir evenly at room temperature to obtain a premix.

[0045] Step 2: Preparation of flame-retardant and high-temperature resistant material The premixed material is added to a twin-screw extruder for melt mixing, pelletized and dried to obtain a flame-retardant and high-temperature resistant material; The temperature of each section of the twin-screw extruder was set to 160℃, the screw speed was 200rpm, and the pellets were dried at 80℃ for 4 hours.

[0046] Step 3: Prepare the armor layer Four parallel cable cores 1-1 are wrapped with insulating rubber 1-2 and filler 1-3 in sequence and tied tightly with wrapping tape 1-4 to form conductive core 1. Inner lining material is extruded on the outside of conductive core 1 to form inner lining layer 2. Multiple galvanized round steel wires are tightly wrapped in a single layer spiral around the outer periphery of inner lining layer 2 with constant tension on an armoring machine to form armor layer 3.

[0047] Step 4: Prepare the outer sheath layer Flame-retardant and high-temperature resistant material is added to a single-screw extruder and melt-extruded onto the outside of the armor layer 3 at a temperature of 150°C to form the outer sheath layer 4. The temperatures of the single-screw extruder from the feeding section to the die head are set to 140℃, 155℃, 165℃, and 170℃ respectively, the screw speed is 30 rpm, and the outer sheath thickness is 2.0 mm.

[0048] Step 5: Preparation of flame-retardant and high-temperature resistant power cable materials The cable is fed into a continuous hot air circulating tunnel furnace and kept at 180°C for 30 minutes. After being cooled with 15°C cooling water, it is coiled to obtain flame-retardant and high-temperature resistant power cable material.

[0049] High-temperature heat treatment initiates the cyclothermal ring-opening polymerization of benzoxazine to form a cross-linked polybenzoxazine network, which, together with the polyurethane matrix, constructs a semi-interpenetrating network structure, synergistically enhancing the flame retardancy and high-temperature resistance of power cable materials. Example

[0050] This embodiment provides a method for preparing a flame-retardant and high-temperature resistant power cable material, including the following steps: Step 1: Preparation of premix N,N'-diphenyl-p-phenylenediamine, fatty acid amide, 3-aminopropyltriethoxysilane and N,N'-bis(2,6-diisopropylphenyl)carbodiimide were mixed evenly in a mass ratio of 4:1:1:2 to obtain the excipient, which was then set aside. Weigh out the following by weight: 90 parts of polyether-type thermoplastic polyurethane elastomer, 20 parts of siloxane-modified benzoxazine resin prepared in Example 5, 12.5 parts of hybrid microspheres prepared in Example 2, and 2 parts of excipients. Add them to a high-speed homogenizer and stir evenly at room temperature to obtain a premix.

[0051] Step 2: Preparation of flame-retardant and high-temperature resistant material The premixed material is added to a twin-screw extruder for melt mixing, pelletized and dried to obtain a flame-retardant and high-temperature resistant material; The temperature of each section of the twin-screw extruder was set to 175℃, the screw speed was 300rpm, and the pellets were dried at 85℃ for 5 hours.

[0052] Step 3: Prepare the armor layer Four parallel cable cores 1-1 are wrapped with insulating rubber 1-2 and filler 1-3 in sequence and tied tightly with wrapping tape 1-4 to form conductive core 1. Inner lining material is extruded on the outside of conductive core 1 to form inner lining layer 2. Multiple galvanized round steel wires are tightly wrapped in a single layer spiral around the outer periphery of inner lining layer 2 with constant tension on an armoring machine to form armor layer 3.

[0053] Step 4: Prepare the outer sheath layer Flame-retardant and high-temperature resistant material is added to a single-screw extruder and melt-extruded onto the outside of the armor layer 3 at a temperature of 160°C to form the outer sheath layer 4. The temperatures of the single-screw extruder from the feeding section to the die head are set to 140℃, 155℃, 165℃, and 170℃ respectively, the screw speed is 45 rpm, and the outer sheath thickness is 2.7 mm.

[0054] Step 5: Preparation of flame-retardant and high-temperature resistant power cable materials The cable is fed into a continuous hot air circulating tunnel furnace and kept at 190°C for 45 minutes. After being cooled by 20°C cooling water, it is coiled to obtain flame-retardant and high-temperature resistant power cable material. Example

[0055] This embodiment provides a method for preparing a flame-retardant and high-temperature resistant power cable material, including the following steps: Step 1: Preparation of premix N,N'-diphenyl-p-phenylenediamine, fatty acid amide, 3-aminopropyltriethoxysilane and N,N'-bis(2,6-diisopropylphenyl)carbodiimide were mixed evenly in a mass ratio of 4:1:1:2 to obtain the excipient, which was then set aside. Weigh out the following by weight: 100 parts of polyether-type thermoplastic polyurethane elastomer, 25 parts of siloxane-modified benzoxazine resin prepared in Example 6, 15 parts of hybrid microspheres prepared in Example 3, and 3 parts of excipients. Add them to a high-speed homogenizer and stir evenly at room temperature to obtain a premix.

[0056] Step 2: Preparation of flame-retardant and high-temperature resistant material The premixed material is added to a twin-screw extruder for melt mixing, pelletized and dried to obtain a flame-retardant and high-temperature resistant material; The temperature of each section of the twin-screw extruder was set to 190℃, the screw speed was 400rpm, and the pellets were dried at 90℃ for 6 hours.

[0057] Step 3: Prepare the armor layer Four parallel cable cores 1-1 are wrapped with insulating rubber 1-2 and filler 1-3 in sequence and tied tightly with wrapping tape 1-4 to form conductive core 1. Inner lining material is extruded on the outside of conductive core 1 to form inner lining layer 2. Multiple galvanized round steel wires are tightly wrapped in a single layer spiral around the outer periphery of inner lining layer 2 with constant tension on an armoring machine to form armor layer 3.

[0058] Step 4: Prepare the outer sheath layer Flame-retardant and high-temperature resistant material is added to a single-screw extruder and melt-extruded onto the outside of the armor layer 3 at a temperature of 170°C to form the outer sheath layer 4. The temperatures of the single-screw extruder from the feeding section to the die head are set to 140℃, 155℃, 165℃, and 170℃ respectively, the screw speed is 60 rpm, and the outer sheath thickness is 3.5 mm.

[0059] Step 5: Preparation of flame-retardant and high-temperature resistant power cable materials The cable is fed into a continuous hot air circulating tunnel furnace and kept at 200°C for 60 minutes. After being cooled by cooling water at 25°C, it is coiled to obtain flame-retardant and high-temperature resistant power cable material.

[0060] Comparative Example 1 The difference between this comparative example and Example 9 is that, in step one, when preparing the premix, an equal amount of aminated hollow glass microspheres were used instead of hybrid microspheres. Comparative Example 2 The difference between this comparative example and Example 9 is that, in step one, hollow glass microspheres are used to replace the hybrid microspheres in equal amounts when preparing the premix.

[0061] Comparative Example 3 The difference between this comparative example and Example 9 is that, in step one, when preparing the premix, an equal amount of commercially available bisphenol A type benzoxazine resin is used instead of siloxane-modified benzoxazine resin.

[0062] Performance testing: Flame retardant performance: The sheath carbonization damage length and afterflame time of the power cable materials prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 18380.12-2022 "Cables and optical cables - Burning tests under flame conditions - Part 12: Vertical flame spread test of single insulated wires and cables - 1 kW premixed flame test method". High temperature resistance: The high temperature heat shrinkage rate of the power cable materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested by heating at 120℃±2℃ for 1h in accordance with the standard GB / T 2951.13-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables - Part 13: General Test Methods - Density Determination Method - Water Absorption Test - Shrinkage Test". Mechanical properties: Referring to standard GB / T 2951.11-2008 "General test methods for insulation and sheath materials of cables and optical fibers - Part 11: General test methods for thickness and dimensional measurement and mechanical property testing", the outer sheath layer of the power cable materials prepared in Examples 7-9 and Comparative Examples 1-3 was peeled off, and the tensile strength and elongation at break of the outer sheath layer were determined at a tensile rate of 50 mm / min. The specific data are shown in Table 1.

[0063] Table 1 - Performance Test Data for Each Sample

[0064] Data Analysis: A comparative analysis of the above tables shows that the power cable material prepared by this invention has a sheath carbonization damage length of 28 mm, an afterburning time of 8 s, a high-temperature heat shrinkage rate of 1.2%, an outer sheath tensile strength of 32.5 MPa, and a breaking elongation of 591%. All of these data are superior to the comparative example.

[0065] This invention uses polyether-type thermoplastic polyurethane as the matrix, and prepares hybrid microspheres by silanization grafting and metal and polyphenol coordination network coating of hollow glass microspheres. The siloxane segments are embedded into the benzoxazine skeleton by Mannich condensation to prepare modified resin. The two are blended and extruded and then crosslinked at high temperature to form a semi-interpenetrating network, which synergistically improves the flame retardant and high temperature resistance properties of power cable materials.

[0066] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame-retardant and high-temperature resistant power cable material, characterized in that, It includes a conductive core (1), an inner lining layer (2), an armor layer (3), and an outer sheath layer (4) arranged sequentially from the inside to the outside. The conductive core (1) includes four parallel cable cores (1-1) and insulating rubber (1-2), filler (1-3), and wrapping tape (1-4) covering the outside of the cable core. The outer sheath layer (4) is obtained by melting and extruding flame-retardant and high-temperature resistant material on the outside of the armor layer (3). The flame-retardant and high-temperature resistant material comprises the following components by weight: 80-100 parts of polyether-type thermoplastic polyurethane elastomer, 15-25 parts of siloxane-modified benzoxazine resin, 10-15 parts of hybrid microspheres and 1-3 parts of auxiliary materials. The siloxane-modified benzoxazine resin was prepared by the following steps: A1. Tetramethyltetraphenylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and toluene were placed in a reaction vessel under nitrogen atmosphere and stirred. The reaction vessel was heated to 100-110℃, tetramethylammonium hydroxide was added, and the reaction was maintained at this temperature for 4-6 hours. The reaction vessel was then heated to 145-155℃ and the reaction was maintained at this temperature for 1-2 hours. The post-treatment yielded amino-terminated polymethylphenylsiloxane. A2. Place paraformaldehyde in a reaction vessel and stir. Heat the reaction vessel to 40-50℃, add 2,2-bis(4'-hydroxyphenyl)propane and toluene, stir for 10-15 min, add amino-terminated polymethylphenylsiloxane, heat the reaction vessel to 75-85℃, and keep the reaction at this temperature for 4-6 h. Post-treatment yields siloxane-modified benzoxazine resin.

2. The flame-retardant and high-temperature resistant power cable material according to claim 1, characterized in that, In step A1, the ratio of tetramethyltetraphenylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, toluene and tetramethylammonium hydroxide is 3-5g:1.2-1.6g:10-12mL:0.01-0.03g.

3. The flame-retardant and high-temperature resistant power cable material according to claim 1, characterized in that, In step A2, the ratio of paraformaldehyde, 2,2-bis(4'-hydroxyphenyl)propane, toluene and amino-terminated polymethylphenylsiloxane is 0.1-0.3g:0.4-0.6g:8-10mL:1.5-2.0g.

4. The flame-retardant and high-temperature resistant power cable material according to claim 1, characterized in that, The hybrid microspheres are prepared by the following steps: B1. Hollow glass microspheres, deionized water and ethanol are placed in a reaction vessel and stirred. 3-aminopropyltriethoxysilane is added. The reaction vessel is heated to 55-65℃ and kept at this temperature for 3-5 hours. After post-treatment, aminated hollow glass microspheres are obtained. B2. Place aminated hollow glass microspheres and deionized water in a reaction vessel and stir. Add tannic acid and stir for 25-35 minutes. Add ferric chloride hexahydrate aqueous solution and stir at room temperature for 1-2 hours. Post-treatment yields hybrid microspheres.

5. The flame-retardant and high-temperature resistant power cable material according to claim 4, characterized in that, In step B1, the ratio of the hollow glass microspheres, deionized water, ethanol and 3-aminopropyltriethoxysilane is 1-2g:4-6mL:17-19mL:0.5-0.7g.

6. The flame-retardant and high-temperature resistant power cable material according to claim 4, characterized in that, In step B2, the ratio of the amount of aminated hollow glass microspheres, deionized water, tannic acid and ferric chloride hexahydrate aqueous solution is 2-4g:20-25mL:0.4-0.6g:5-7mL. The ferric chloride hexahydrate aqueous solution is obtained by mixing ferric chloride hexahydrate and deionized water at a ratio of 1g:20mL.

7. A method for preparing the flame-retardant and high-temperature resistant power cable material as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Add polyether-type thermoplastic polyurethane elastomer, siloxane-modified benzoxazine resin, hybrid microspheres and excipients into a high-speed homogenizer and stir evenly at room temperature to obtain a premix. S2. The premixed material is added to a twin-screw extruder for melt mixing, pelletized and dried to obtain a flame-retardant and high-temperature resistant material; S3. The four parallel cable cores (1-1) are wrapped with insulating rubber (1-2) and filler (1-3) in sequence and tied with wrapping tape (1-4) to form conductive core (1). Inner lining material is extruded on the outside of conductive core (1) to form inner lining layer (2). Multiple galvanized round steel wires are tightly wrapped in a single spiral along the outer periphery of inner lining layer (2) with constant tension on the armoring machine to form armor layer (3). S4. Add flame-retardant and high-temperature resistant material into a single screw extruder and melt-extrude it onto the outside of the armor layer (3) at a temperature of 150-170℃ to form an outer sheath layer (4). S5. The cable is fed into a continuous hot air circulating tunnel furnace and subjected to heat treatment at 180-200℃. After cooling the coil, flame-retardant and high-temperature resistant power cable material is obtained.

8. The method for preparing a flame-retardant and high-temperature resistant power cable material according to claim 7, characterized in that, In step S1, the inner lining material is chlorinated polyethylene, and the auxiliary materials are composed of antioxidant, lubricant, silane coupling agent and hydrolysis stabilizer in a mass ratio of 4:1:1:2.

Images