Intelligent early warning cable and preparation method thereof

Abstract

The invention discloses an intelligent early warning cable, and relates to the technical field of cables. The cable comprises a conductor, a cross-linked polyethylene insulating layer, an intelligent early warning layer, a filling layer, a wrapping layer and a second flame-retardant sheath layer, wherein the intelligent early warning layer is composed of optical fibers, resin, a hose, aramid fiber ropes, a woven mesh and a first flame-retardant sheath material. According to the first flame-retardant sheath layer, various polymers are compounded to serve as a resin matrix, an inorganic flame retardant and a modified flame retardant are matched to form a synergistic flame-retardant system, and the modified flame retardant is prepared from a phosphorus-hydrogen bond-containing monomer I, double-bond-containing siloxane, a hydroxyl-containing monomer II and the like through a specific process and has flame-retardant efficiency and mechanical performance. In the preparation process, the conductors, the insulating wire cores and the intelligent early warning layer are molded step by step, and then cabling, wrapping and sheath extruding are performed, so that the final product has excellent flame-retardant effect, mechanical strength, optical transmission stability and pressure resistance and is suitable for multi-scene requirements.

Description

Technical Field

[0001] This application relates to the technical field of cables, and in particular to an intelligent early warning cable and its manufacturing method. Background Technology

[0002] With the acceleration of urbanization and the booming development of large-scale infrastructure construction, various scenarios are placing higher demands on the comprehensive performance of monitoring and transmission systems. Distributed fiber optic sensing technology, with its unique advantages, has ushered in a period of rapid development in the monitoring field. This technology not only boasts a lifespan of decades and requires no additional maintenance costs, but also features long transmission distances, compact size, and outstanding economic efficiency. Most importantly, it can withstand electromagnetic interference, extreme temperature and humidity, and other harsh environmental influences, and is highly compatible with most building and engineering materials in terms of mechanical adaptability and chemical stability. These characteristics make it an ideal choice for building ultra-large-scale, high-precision monitoring networks.

[0003] However, conventional cables currently in widespread use have significant functional shortcomings. Most of these cables focus solely on power or signal transmission, lacking effective real-time monitoring capabilities. Even when some products attempt to integrate optical fibers, they often simply bundle the fibers to the cable surface. This crude approach not only makes the fibers susceptible to damage during construction and maintenance but also fails to accurately perceive the cable's overall condition. In the face of natural or man-made disasters such as fires and earthquakes, conventional cables struggle to quickly capture critical signals like sudden temperature changes and structural deformations, often resulting in monitoring delays, missed opportunities for optimal response, and ultimately, unnecessary loss of life and property.

[0004] Therefore, intelligent early warning power cables integrating power transmission and intelligent monitoring have emerged. These innovative cables deeply integrate the core advantages of cables and optical fibers; they are not simply physical superpositions, but rather optical fibers are cleverly embedded within the cable's internal structure. They retain the reliable power transmission function of traditional cables while achieving comprehensive sensing of the cable's operating status through embedded optical fibers. This allows for rapid response to subtle changes such as temperature fluctuations and deformation vibrations, thereby accurately locating the location and development trend of disasters such as fires and earthquakes. Furthermore, by recording unique information into the optical fibers, cable identification can be achieved, greatly facilitating line differentiation during construction, maintenance and troubleshooting during operation and maintenance, and anti-theft early warning, significantly improving the intelligent management level of the power system.

[0005] The construction of power systems in super high-rise building complexes places stringent requirements on the comprehensive performance of cables. Super high-rise buildings are often densely populated and functionally complex, with power lines densely packed within confined spaces such as walls and utility shafts. In the event of a fire, the fire can spread rapidly and rescue efforts are extremely difficult. Furthermore, these buildings are prone to structural deformation during geological disasters such as earthquakes, which can lead to cable damage and breakage. Applying these intelligent early warning cables to super high-rise building complexes can not only ensure the core power supply but also monitor line temperature and structural condition in real time through embedded fiber optics, providing early warnings of fire hazards and deformation risks. Combined with identification functions, this simplifies construction and maintenance processes, thus building a solid defense for the safe operation of super high-rise buildings. Summary of the Invention

[0006] The purpose of this application is to provide an intelligent early warning cable with good flame retardant effect and mechanical properties.

[0007] Firstly, the intelligent early warning cable and its manufacturing method provided in this application adopt the following technical solution: A smart early warning layer includes: an optical fiber, resin coated on both sides of the optical fiber, a flexible tube threaded onto the optical fiber, an aramid fiber rope disposed on the flexible tube, a braided mesh disposed on the aramid fiber rope, and a first flame-retardant sheath material disposed on the braided mesh. The first flame-retardant sheath layer comprises: 25-35 parts of ethylene-butyl acrylate copolymer, 15-25 parts of ethylene-butene copolymer, 15-25 parts of metallocene-catalyzed linear low-density polyethylene, 5-10 parts of compatibilizer, 120-135 parts of inorganic flame retardant, 15-30 parts of modified flame retardant, 1-2 parts of lubricant, 1-2 parts of antioxidant, and 4-8 parts of color masterbatch; the modified flame retardant comprises a phosphorus-hydrogen bond-containing monomer one, a double bond-containing siloxane, and a hydroxyl-containing monomer two; the mass ratio of the phosphorus-hydrogen bond-containing monomer one, the double bond-containing siloxane, and the hydroxyl-containing monomer two is (0.5-2):1:(1-2).

[0008] By adopting the above technical solution, the resin matrix is ​​a blend of ethylene-butyl acrylate copolymer, ethylene-butene copolymer, and metallocene-catalyzed linear low-density polyethylene. The compatibility and flexibility of different polymer segments complement each other, ensuring both the mechanical strength of the sheath and improving processing fluidity. Compatibilizers promote interfacial bonding between resin phases, lubricants optimize material dispersibility during processing, antioxidants delay thermo-oxidative aging, color masterbatches ensure appearance stability, and inorganic flame retardants, as the basic flame-retardant component, exert preliminary flame-retardant effects through endothermic decomposition and dilution of combustible gases. A phosphorus-hydrogen bond-containing monomer I reacts with a double-bond-containing siloxane to form a phosphorus-silicon-containing intermediate. This intermediate then reacts with a hydroxyl-containing monomer II to prepare a modified flame-retardant product containing phosphorus and silicon flame-retardant elements. A specific mass ratio ensures sufficient reaction of each monomer, guaranteeing both the appropriate content of phosphorus and silicon elements and enhancing the interaction with the resin matrix and inorganic flame retardant through the hydroxyl groups. When the system burns, the phosphorus element in the modified flame retardant promotes char layer formation, while the silicon element enhances the density of the char layer. The prepared modified flame retardant works synergistically with the inorganic flame retardant. On the one hand, the inert gas generated by the decomposition of the inorganic flame retardant further dilutes the flammable atmosphere; on the other hand, the dense char layer blocks heat and oxygen transfer, while inhibiting the release of flammable volatiles generated by polymer pyrolysis. Ultimately, this achieves excellent synergistic flame retardant effects, balancing the mechanical properties and flame retardant efficiency of the sheath.

[0009] Optionally, the modified flame retardant further includes pentaerythritol phosphate; the mass ratio of the phosphorus-hydrogen bond-containing monomer one, the double bond-containing siloxane, the hydroxyl-containing monomer two, and the pentaerythritol phosphate is (0.5-2):1:(1-2):(0.1-0.5).

[0010] By adopting the above technical solution, the addition of pentaerythritol phosphate to the modified flame retardant can further enhance the synergistic flame retardant effect. As a phosphorus-based flame retardant, pentaerythritol phosphate decomposes during combustion to generate acidic substances such as phosphoric acid, promoting polymer dehydration and carbonization, and accelerating the formation of a dense char layer. This char layer effectively blocks heat transfer and oxygen entry. Simultaneously, the inert gases released during its decomposition can dilute the concentration of combustible gases, helping to inhibit the spread of combustion. Furthermore, the polyhydroxy structure of pentaerythritol phosphate can interact with the siloxanes and resin matrix contained in the intermediates, improving the compatibility and dispersibility of the flame retardant system, making the flame retardant functions of phosphorus, silicon, and inorganic flame retardants more synergistic and efficient, further optimizing the flame retardant performance and thermal stability of the sheath.

[0011] Optionally, the phosphorus-hydrogen bond-containing monomer is any one of diphenylphosphine oxide, phenylphosphonic acid, and flame retardant ODOPB.

[0012] By employing the above technical solutions, all three substances possess active phosphorus-hydrogen bonds, enabling efficient addition reactions with siloxanes containing double bonds. Diphenylphosphine oxide molecules contain a symmetrical aromatic ring structure; after the reaction, the rigid framework of the aromatic ring enhances the thermal stability and hydrophobicity of the modified flame retardant. Simultaneously, the aromatic ring exhibits better compatibility with the resin matrix, reducing flame retardant aggregation. Phenylenic acid contains a benzene ring structure; the benzene ring's steric hindrance effectively inhibits intermolecular aggregation of the modified flame retardant, improving its dispersion uniformity in the system. Flame retardant ODOPB contains a unique rigid cyclic structure and multiple phosphorus-oxygen active sites. The cyclic structure readily forms a dense char layer during combustion, while the numerous phosphorus-oxygen sites increase the content of flame-retardant elements.

[0013] Optionally, the hydroxyl-containing monomer II is any one of attapulgite, montmorillonite, and hydrotalcite.

[0014] By adopting the above technical solutions, the hydroxyl-containing monomers selected are attapulgite, montmorillonite, and hydrotalcite, all of which are rich in hydroxyl groups and can react with the siloxane groups contained in the modified flame retardant intermediates. Attapulgite has a fibrous structure, a large specific surface area, and strong adsorption capacity. After the reaction, it can not only enhance the interfacial bonding force between the modified flame retardant and the resin matrix and improve the mechanical strength of the sheath, but its fibrous skeleton can also adsorb combustible volatiles during combustion, helping to suppress the spread of flames. Montmorillonite is a layered silicate with intercalation characteristics between its layers, which can accommodate the phosphorus and silicon components in the modified flame retardant. During combustion, it can form a nano-barrier, effectively blocking combustion. At the same time, the layered structure is conducive to the uniform dispersion of the flame retardant in the matrix, avoiding agglomeration. Hydrotalcite is a layered double hydroxide with excellent thermal stability. When heated and decomposed, it can release gas to dilute the flammable atmosphere and reduce the system temperature through endothermic reaction. In addition, its hydroxyl density is high and its reactivity with intermediates is strong, which can further enhance the synergistic effect of phosphorus, silicon and inorganic flame retardants, and improve the overall flame retardant efficiency and material thermal stability.

[0015] Optionally, the inorganic flame retardant is any one or more of magnesium hydroxide and aluminum hydroxide.

[0016] By adopting the above technical solution and selecting magnesium hydroxide and aluminum hydroxide as inorganic flame retardants, the flame retardant mechanism of metal hydroxides is consistent. Under high-temperature conditions, they absorb a large amount of heat, rapidly reducing the surface temperature of the material and slowing the combustion process; simultaneously, they decompose and release water vapor, forming a localized inert atmosphere that blocks oxygen from contacting the matrix, thus slowing the flame propagation speed; the inorganic substances subsequently decomposed and transformed also form a dense protective layer on the material surface, isolating oxygen from combustibles and further strengthening the flame retardant barrier. Aluminum hydroxide has a relatively low decomposition temperature, allowing it to quickly absorb heat and release gas in the early stages of combustion; magnesium hydroxide has a higher decomposition temperature, providing continuous flame retardant protection at high temperatures and extending the duration of flame retardancy. Furthermore, both are non-toxic and non-volatile.

[0017] Optionally, the preparation method of the modified flame retardant includes the following steps: S1. The monomer containing phosphorus hydrogen bonds is heated, an inert gas is introduced, a siloxane containing double bonds is added, heated, stirred, and cooled to room temperature to obtain an intermediate. S2. Dissolve the hydroxyl-containing monomer dipentaerythritol phosphate in a solvent, heat, add the intermediate prepared in step S1, stir, centrifuge, wash, and vacuum dry to obtain the modified flame retardant.

[0018] By adopting the above technical solution, in step S1, the molten monomer containing phosphorus-hydrogen bonds is simultaneously introduced into an inert gas atmosphere. This ensures that the reactants are in full contact, facilitating a complete double-bond addition reaction with the siloxane containing double bonds, while also avoiding side reactions such as oxidation of the materials during the reaction, thus obtaining a structurally stable intermediate. In step S2, the hydroxyl-containing monomer is dissolved in a solvent, improving its dispersibility and making the reaction with the hydroxyl group of the intermediate more uniform and thorough. Subsequent centrifugal washing removes unreacted raw materials, and vacuum drying avoids solvent residue, further ensuring the purity of the modified flame retardant.

[0019] Optionally, the heating temperature in step S1 is 140-155℃, and the heating temperature in step S2 is 70-90℃.

[0020] By adopting the above technical solution, the heating temperature in step S1 is suitable for the addition reaction of a monomer containing phosphorus hydrogen bonds with a siloxane containing double bonds, ensuring the stability of the intermediate structure. The mild temperature in step S2 is suitable for the reaction involving hydroxyl groups, preventing high temperatures from damaging the product structure.

[0021] A smart early warning cable includes: a conductor made of copper wire, a cross-linked polyethylene insulation layer, a smart early warning layer, a filler layer made of filler rope, a wrapping layer made of flame-retardant tape, and a second flame-retardant sheath layer; the cross-linked polyethylene insulation layer covers the conductor to form an insulated core, the smart early warning layer and multiple insulated cores are twisted together to form a cable core, the wrapping layer is wrapped around the cable core, the filler is disposed between the insulated core and the wrapping layer, and the second flame-retardant sheath layer is extruded onto the wrapping layer.

[0022] By adopting the above technical solution, the intelligent early warning cable, through a hierarchical adaptation design of copper wire conductor, cross-linked polyethylene insulation layer, intelligent early warning layer, filler rope filling layer, flame-retardant tape wrapping layer and second flame-retardant sheath layer, not only relies on copper wire conductor to ensure stable power transmission performance, but also uses cross-linked polyethylene insulation layer to achieve reliable electrical isolation effect. The intelligent early warning layer can monitor the cable operating status in real time and promptly report abnormal information. The filler rope filling layer can optimize the stability of the cable core structure. The flame-retardant tape wrapping layer and the second flame-retardant sheath layer form a dual flame-retardant protection system, effectively improving the fire safety performance of the cable. The synergistic effect of each component endows the cable with excellent electrical performance, early warning function and safety protection capability, meeting the usage requirements in complex scenarios.

[0023] Optionally, the cross-linked polyethylene insulation layer comprises: silane grafting material and catalyst masterbatch; the silane grafting material comprises 40-100 parts polyethylene, 1-3 parts silane cross-linking agent, 0.3-1 parts initiator, and 0.1-2 parts first antioxidant; the catalyst masterbatch comprises 80-100 parts polyethylene, 1-2 parts catalyst, 5-10 parts lubricant, 0.5-1.5 parts second antioxidant, and 0.05-1 part copper inhibitor.

[0024] By adopting the above technical solution, the cross-linked polyethylene insulation layer formulation achieves insulation performance through silane grafting material and catalytic masterbatch. The silane cross-linking agent undergoes a grafting reaction with polyethylene under the action of an initiator, and works in conjunction with various raw materials in the catalytic masterbatch to promote cross-linking and form a stable network structure, thereby improving the mechanical strength and heat resistance of the insulation layer. The first and second antioxidants synergistically inhibit thermo-oxidative aging, the copper inhibitor prevents the catalytic degradation of the insulation layer by copper conductors, and the lubricant optimizes processing dispersibility.

[0025] Secondly, the flame-retardant cable sheath, intelligent early warning cable, and their preparation method provided in this application adopt the following technical solutions: A method for manufacturing an intelligent early warning cable includes the following steps: Step 1: Twist multiple copper wires together and compress them to form a conductor; Step 2: Wrap the cross-linked polyethylene insulation layer over the conductor to obtain an insulated wire core; Step 3: Coat both sides of the optical fiber with UV-cured resin to form a multimode optical fiber. Seal the multimode optical fiber with a flexible tube thread. Place the aramid fiber rope on the flexible tube longitudinally and fix it with a braided mesh. Extrude the first flame-retardant sheath layer and form it to prepare the intelligent early warning layer. Step 4: After stranding the intelligent early warning layer and multiple insulated wire cores into a cable core, wrap the wrapping layer around the cable core and fill the space between the insulated wire core and the wrapping layer. Step 5: Extrude the second flame-retardant sheath layer onto the wrapping layer to obtain an intelligent early warning cable.

[0026] By employing the above technical solution, this manufacturing method ensures the structural stability and excellent electrical performance of the intelligent early warning cable through a step-by-step process. Step one involves stranding and compacting copper wires to improve conductor conductivity and mechanical strength. Step two involves coating with a cross-linked polyethylene insulation layer to ensure electrical insulation performance meets standards. Step three involves coating special optical fibers with UV-cured resin for protection, threading them, and adding aramid fiber ropes, enhancing the fiber's damage resistance and tensile strength while ensuring stable transmission of early warning signals. Step four involves stranding, wrapping, and filling the cable to create a regular cable core structure. The filling layer fixes the core position, and the wrapping layer strengthens the overall integrity of the cable core and provides initial flame-retardant protection. Step five involves extruding a flame-retardant sheath to form the final protective barrier. The intelligent early warning cable manufactured using this method not only fulfills the basic transmission function of a cable but also ensures the efficient operation of the intelligent early warning layer, improving overall comprehensive performance.

[0027] In this preparation method, some of the raw materials and their functions are as follows: Monomer 1 containing phosphorus-hydrogen bonds: Monomer 1 contains active phosphorus-hydrogen bonds, which can react with siloxanes containing double bonds through a double bond addition reaction to form a phosphorus-silicon structure intermediate. This intermediate then reacts with the hydroxyl group of monomer 2 containing hydroxyl groups to generate a modified flame retardant. Its phosphorus element can promote the formation of a dense char layer during combustion, while the silicon element enhances the stability of the char layer. Synergistically with the inorganic flame retardant, it both blocks heat and oxygen through the char layer and assists the inorganic flame retardant in diluting flammable gases. At the same time, the specific ratio allows the reaction to be complete, improving compatibility with the resin matrix and balancing flame retardant efficiency and sheath mechanical properties.

[0028] Double-bond siloxanes: Siloxanes containing double bonds have active double bonds that can react with monomers containing phosphorus-hydrogen bonds via double bond addition reactions to form phosphorus-silicon structural intermediates. The siloxane groups of these intermediates then react with the hydroxyl groups of monomers containing hydroxyl groups. Simultaneously, siloxanes can interact with the polyhydroxyl groups of pentaerythritol phosphate esters, enhancing the compatibility and dispersibility of the flame-retardant system, ensuring both flame-retardant efficiency and optimizing the mechanical properties and processing stability of the sheath.

[0029] Hydroxyl-containing monomer II: Hydroxyl-containing monomer II is rich in hydroxyl groups, which can react with siloxane groups in modified flame retardant intermediates. Its structural properties enhance the interfacial bonding with the resin matrix and improve the mechanical strength of the sheath; during combustion, it can form a nano-barrier or adsorb combustible volatiles, assisting in blocking combustion.

[0030] Pentaerythritol phosphate: Pentaerythritol phosphate contains a polyhydroxyl structure, which can react with siloxanes in modified flame retardant intermediates. As a phosphorus-based flame retardant, it decomposes during combustion to generate acidic substances such as phosphoric acid, promoting polymer dehydration and carbonization, accelerating the formation of a dense char layer to block heat and oxygen; at the same time, it releases inert gases to dilute the flammable atmosphere. The polyhydroxyl groups can also improve the compatibility and dispersibility of the flame retardant system with the resin matrix, promote the efficient synergy of phosphorus, silicon and inorganic flame retardants, and further optimize the flame retardant performance and thermal stability of the sheath.

[0031] Ethylene-butyl acrylate copolymer: Ethylene-butyl acrylate copolymer contains ester functional groups, which can improve the segmental compatibility with ethylene-butene copolymer and metallocene-catalyzed linear low-density polyethylene, and can also synergistically enhance the interfacial bonding of resins with compatibilizers. Its flexible segments can compensate for the rigidity of other resins, giving the sheath both mechanical strength and processing fluidity; the polarity of the ester groups can also improve the dispersibility with the flame retardant system, help improve the uniformity of flame retardant distribution in the matrix, and ensure that the first flame retardant sheath layer has both good processability and maintains stable mechanical and flame retardant synergistic effects.

[0032] Ethylene-butene copolymer: Ethylene-butene copolymers contain flexible olefin segments, which can form good compatibility with the ester groups of ethylene-butyl acrylate copolymers and the segments of metallocene-catalyzed linear low-density polyethylene, enhancing the synergistic effect of the resin matrix through segment complementarity. Its flexible characteristics improve the flowability of the sheath during processing, while simultaneously ensuring the mechanical strength of the sheath by cooperating with the rigid segments of other resins. It can also assist compatibilizers in promoting interfacial bonding between resin phases, reducing phase separation, and allowing for more uniform dispersion of the flame retardant in the matrix, thus balancing the molding processability of the first flame-retardant sheath layer with the overall mechanical and flame-retardant performance stability.

[0033] Metallocene-catalyzed linear low-density polyethylene (LLDPE): Metallocene-catalyzed LLDPE has a regular molecular chain structure containing olefin segments, which are highly compatible with the ester groups of ethylene-butyl acrylate copolymers and the flexible segments of ethylene-butene copolymers. This segmental complementarity enhances the synergistic effect between the resin matrix and the LLDPE. Its regular structure improves the mechanical strength of the sheath, while the olefin segments and compatibilizer synergistically promote interfacial bonding between resin phases, reducing phase separation. It also optimizes processing flowability, allowing for more uniform dispersion of the flame retardant in the matrix, balancing the mechanical stability and molding processability of the first flame-retardant sheath layer, and ensuring a balanced overall performance.

[0034] Polyethylene: As the matrix of cross-linked polyethylene insulation, polyethylene's olefin segments can undergo grafting reactions with silane cross-linking agents under the action of initiators. Combined with catalytic masterbatch, this promotes cross-linking and forms a stable network structure, enhancing the mechanical strength and heat resistance of the insulation layer. Its non-polar segments are well-compatible with additives such as antioxidants and copper inhibitors, supporting and assisting these components in their function. For example, it synergistically delays thermo-oxidative aging with antioxidants and prevents catalytic degradation of copper conductors with copper inhibitors. Simultaneously, the insulating properties of polyethylene ensure that the cable's electrical insulation performance meets standards, providing reliable protection for the conductor and guaranteeing the stable electrical performance and safe operation of the intelligent early warning cable.

[0035] Silane crosslinking agent: Silane crosslinking agents contain reactive groups that, under the action of an initiator, undergo a grafting reaction with the olefin segments of polyethylene. Combined with catalytic masterbatch, this promotes crosslinking and the formation of a stable network structure. This network significantly improves the mechanical strength and heat resistance of the crosslinked polyethylene insulation layer, reducing thermal deformation. Simultaneously, the crosslinked structure enhances the insulation layer's ability to carry additives, and assists antioxidants and other components in working synergistically to delay thermo-oxidative aging, ensuring stable performance of the insulation layer during long-term use. This provides durable and reliable electrical insulation protection for the conductor, guaranteeing the electrical performance safety of intelligent early warning cables.

[0036] Copper inhibitor: The copper inhibitor exists in the catalytic masterbatch of cross-linked polyethylene insulation layer. Its active functional groups can chelate with copper ions released from the copper conductor, forming a stable complex. This inhibits the activity of copper ions in catalyzing the oxidative degradation of polyethylene, preventing the insulation layer from aging and cracking due to copper catalysis. In summary, this application includes at least one of the following beneficial technical effects: 1. Compared with the prior art, a phosphorus-hydrogen bond-containing monomer I and a siloxane containing double bonds undergo an addition reaction under inert gas protection and at a specific temperature to form a phosphorus-silicon structure intermediate. This intermediate then reacts with a hydroxyl-containing monomer II and pentaerythritol phosphate at an appropriate temperature. After centrifugation, washing, and vacuum drying, a modified flame retardant is obtained. The components react fully in a specific ratio, ensuring the product has a stable structure and uniform performance. 2. Compared with existing technologies, the modified flame retardant and inorganic flame retardant work synergistically. Phosphorus promotes polymer carbonization, silicon strengthens the density of the carbon layer, and together with the heat absorption and gas release effect of the inorganic flame retardant, a highly efficient flame retardant system is constructed. This effectively blocks heat and oxygen transfer and inhibits the release of combustible volatiles, significantly improving the flame retardant effect of the intelligent early warning cable, while also taking into account the mechanical strength and light transmission stability of the cable. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the intelligent early warning layer structure of Embodiment 7 of this application; Figure 2 This is a schematic diagram of the overall structure of the intelligent early warning cable according to Embodiment 7 of this application; Detailed Implementation

[0038] Unless otherwise specified, all raw materials used in the embodiments and comparative examples of this application are commercially available products: Flame-retardant filler rope, harness type, manufacturer: Wanyang; Optical fiber, germanium-doped optical fiber used in this application; model: BLY-MM03P, Brillouin; Polyethylene, model: LL1201, ExxonMobil; Flame retardant tape, manufacturer Huitong; First Resin, Model: 3471-1-129A, Covestro; Second resin, model: OP-4-20632, Demas; Aramid fiber rope, model: K29, DuPont; Silane crosslinking agent, model: A-171, Momentive; Initiator, model: Dcp, AkzoNobel; First antioxidant, model: 1010, Leylan; Catalyst, Model: T-9, Evonik; Lubricant, model: 109, can be successfully applied; Second antioxidant, model: 168, Leylan; Anti-copper agent, model: 1150: Weihai Huaen Rubber & Plastics; Metallocene-catalyzed linear low-density polyethylene, model: 3518CB, ExxonMobil; Masterbatch, Model: PE Masterbatch, Wujiang; 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, DOPO, catalog number S46419-500g, Yuanye Biotechnology; Ethylene-butyl acrylate copolymer, model: 2770, Repsol, Spain; Ethylene-butene copolymer, model: DF810, Mitsui, Japan; Compatibilizer, model: MC213, Nengzhiguang; Aluminum hydroxide, 901, Shandong Zhongshun; Magnesium hydroxide: 10FG, Aitek Flame Retardant Materials Co., Ltd. Flame retardant ODOPB, CAS No.: 99208-50-1, Product No.: A208501; Alpha.

[0039] Example 1 A method for manufacturing an intelligent early warning cable includes the following steps: First, a modified flame retardant is prepared.

[0040] 5 kg of diphenylphosphine oxide was heated to melt at 150 °C. Under a nitrogen atmosphere, 10 kg of vinyltrimethoxysilane was added. The mixture was stirred at 500 rpm for 5 h at a constant temperature of 150 °C and then cooled to 20 °C to obtain an intermediate.

[0041] 10 kg of hydrotalcite, 1.5 kg of pentaerythritol phosphate, and 35 kg of ethanol were mixed and stirred at 500 rpm for 30 min. The mixture was heated to 80 °C, and an intermediate was added. The mixture was stirred at 500 rpm for 6 h. The solid was obtained by centrifugation and washed three times with ethanol. The solid was then dried under vacuum at 65 °C for 12 h to obtain the modified flame retardant.

[0042] Then, prepare the cross-linked polyethylene insulation layer material, the first flame-retardant sheath layer material, and the second flame-retardant sheath layer material.

[0043] 50 kg of polyethylene was heated to 145 °C, and 2 kg of silane crosslinking agent, 0.5 kg of initiator, and 0.8 kg of primary antioxidant were added. The mixture was stirred at 500 rpm for 1 hour at 145 °C to obtain a first mixture. The first mixture was cooled to 75 °C, extruded and granulated to obtain the silane grafted material, which was then sealed and stored. 1 kg of catalyst, 7 kg of lubricant, 1 kg of secondary antioxidant, 0.5 kg of copper inhibitor, and 0.5 kg of polyethylene were mixed and stirred at 300 rpm for 30 minutes at 100 °C to prepare a catalyst masterbatch. The silane grafted material was mixed with the catalyst masterbatch to obtain a crosslinked polyethylene insulation layer material for later use.

[0044] 30 kg of ethylene-butyl acrylate copolymer, 10 kg of ethylene-butene copolymer, 20 kg of metallocene-catalyzed linear low-density polyethylene, 8 kg of compatibilizer, 60 kg of magnesium hydroxide, 60 kg of aluminum hydroxide, 20 kg of modified flame retardant, 1.5 kg of lubricant, 1 kg of primary antioxidant, and 5 kg of color masterbatch were mixed and heated to 150°C. The mixture was then stirred at 500 rpm for 1.5 h to obtain a compound. The compound was then fed into a kneader and kneaded at 160°C for 20 min to prepare the first and second flame-retardant sheath layer materials.

[0045] Finally, intelligent early warning cables were manufactured.

[0046] The first step is to prepare the insulated wire core.

[0047] refer to Figure 1 A copper rod with a diameter of 8mm is drawn into a copper single wire with a diameter of 2.21mm (the copper single wire tolerance requirements are 2.21±0.01mm, the copper single wire elongation is ≥37%, and the copper single wire resistivity does not exceed 0.017241Ω·mm). 2 / m), copper monofilaments are arranged in a 1+6+12+18 pattern (from the innermost layer to the outermost layer, 1, 6, 12, and 18 monofilaments respectively). The copper monofilaments are then stranded in layers using a stranding machine, divided into four layers and subjected to three compressions. Each layer is then distributed among 6, 12, and 18 coils respectively. The stranding direction of the monofilaments is set from the inside out according to S, Z, S, with the second outermost layer stranded in the Z direction and the outermost layer stranded in the S direction. The pitch ratio of the outermost monofilament strand does not exceed 12. The measured conductor cross-sectional area is 46.5 mm². 2 The outer diameter of the conductor is 9.7 mm.

[0048] A cross-linked polyethylene (XLPE) insulation layer with a nominal thickness of 1.1 mm was extruded onto the conductor using a 90 mm diameter extruder. The extruder head filter was configured with three layers (80 mesh for the first layer and 100 mesh for the second). The temperatures of the extruder's first to eighth temperature zones were controlled at 150℃, 155℃, 160℃, 170℃, 175℃, 180℃, 185℃, and 185℃, respectively. The screw speed was 50 r / min, and the extrusion pressure was 60 bar. After extrusion, the conductor coated with the XLPE insulation layer was left to stand in an 88℃ water bath for 4 hours to obtain the insulated wire core. The XLPE insulation layer stock was then formed into a XLPE insulation layer.

[0049] The second step is to prepare intelligent early warning optical fibers.

[0050] A 0.6mm optical fiber was coated with a first resin on the inner side and a second resin on the other side, cured for 1 second to obtain a multimode optical fiber. The multimode optical fiber was then spirally encapsulated in a stainless steel flexible tube with a thickness of 0.18mm and an outer diameter of 2.1mm. Aramid fiber ropes were longitudinally attached to the stainless steel flexible tube and secured with a stainless steel braided mesh. A first flame-retardant sheath layer material was then extruded to obtain the intelligent early warning optical fiber. The first flame-retardant sheath layer material was molded to form the first flame-retardant sheath layer, with a measured thickness of 0.5mm and an eccentricity of 25%.

[0051] The third step is to prepare intelligent early warning optical cables.

[0052] refer to Figure 2 The intelligent early warning optical fiber and five insulated cores are cabled using a untwisted twisting method. Flame-retardant filler rope is used to fill the gaps between the intelligent early warning optical fiber and the five insulated cores, and then flame-retardant tape is wrapped around the cable core. Then, a second flame-retardant sheath material is extruded onto the flame-retardant tape, thus obtaining the intelligent early warning cable, wherein the second flame-retardant sheath material is formed into the second flame-retardant sheath layer.

[0053] Example 2 The difference between Example 2 and Example 1 is that 5 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 10 kg of hydrotalcite are replaced with 8 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 18 kg of hydrotalcite. Example 3

[0054] The difference between Example 3 and Example 1 is that 5 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 10 kg of hydrotalcite are replaced with 12 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 15 kg of hydrotalcite. Example 4

[0055] The difference between Example 4 and Example 1 is that 5 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 10 kg of hydrotalcite are replaced with 12 kg of diphenylphosphine oxide, 0 kg of vinyltrimethoxysilane and 12 kg of hydrotalcite. Example 5

[0056] The difference between Example 5 and Example 3 is that 12 kg of diphenylphosphine oxide is replaced with 12 kg of phenylphosphonic acid. Example 6

[0057] The difference between Example 6 and Example 3 is that 12 kg of diphenylphosphine oxide is replaced with 12 kg of flame retardant ODOPB. Example 7

[0058] The difference between Example 7 and Example 6 is that 15 kg of hydrotalcite is replaced with 15 kg of montmorillonite. Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 3 is that 5 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 10 kg of hydrotalcite were replaced with 25 kg of diphenylphosphine oxide, 10 kg of vinyltrimethoxysilane and 8 kg of hydrotalcite. Comparative Example 2

[0060] The difference between Comparative Example 2 and Example 6 is that 12 kg of diphenylphosphine oxide was replaced with 12 kg of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 7 is that 15 kg of montmorillonite was replaced with 15 kg of sepiolite. Comparative Example 4

[0062] The difference between Comparative Example 4 and Example 7 is that no modified flame retardant was added in the preparation of the first flame-retardant sheath layer and the second flame-retardant sheath layer. Test Example 1

[0063] The oxygen index was tested according to GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". The test results are shown in Table 1.

[0064]

[0065] Test Example 2 Optical attenuation: The optical attenuation of the cable was tested using an OTDR optical time domain reflectometer. The test results are shown in Table 2.

[0066] Withstand voltage test: The power frequency withstand voltage test was conducted according to GB / T 12706.1-2020. A withstand voltage of 3.5kV / 5min without breakdown indicates qualification, while breakdown indicates failure. The test results are shown in Table 2.

[0067] Elongation at break and tensile strength: Tensile strength and elongation at break were tested in accordance with GB / T 2951.11-2008 "General test methods for insulation and sheath materials of cables and optical cables - Part 11: General test methods for thickness and dimensional measurement and mechanical properties test". The test results are shown in Table 2.

[0068]

[0069] By observing the data in the table and comparing Examples 1-4 with Comparative Example 1, Example 3 is the best. In Comparative Example 1, the mass ratio of phosphorus-hydrogen bond-containing monomer 1, double-bonded siloxane, and hydroxyl-containing monomer 2 is not within the range of (0.5-2):1:(1-2). When the mass ratio of phosphorus-hydrogen bond-containing monomer 1, double-bonded siloxane, and hydroxyl-containing monomer 2 in the modified flame retardant is appropriate, the phosphorus-based flame retardant elements and layered inorganic materials work synergistically. The phosphorus element catalyzes the formation of char to form a dense char layer to block combustion. The layered structure enhances the stability of the char layer and improves the flame retardant performance. Silane modification improves the compatibility between the flame retardant and the polymer matrix, reduces interface defects, reduces light signal transmission loss, optimizes system dispersion, avoids stress concentration, and improves tensile strength and elongation at break. If the ratio is unbalanced, when there is an excess of phosphorus-containing monomer or an insufficient amount of layered inorganic materials, it will lead to a loose char layer, decreased compatibility, and weakened flame retardant effect.

[0070] Comparing Examples 5-6 with Comparative Example 3, Example 6 was the best, while Comparative Example 2 was the worst. The possible reason is the use of different phosphorus-containing hydrogen-phosphate bonded monomers. The difference in the functional groups of these monomers is the core reason for the performance differentiation. Phenylenic acid contains phosphonic acid groups, is highly polar but has a relatively limited phosphorus content, and has a single functional group, resulting in a mild synergistic effect in flame retardancy and compatibility enhancement. The flame retardant ODOPB may contain multiple phosphorus-oxygen bonds and cyclic conjugated structures, resulting in a higher phosphorus content and the conjugated system enhancing the density and stability of the char layer. Simultaneously, the polar functional groups can form strong interactions with the siloxane groups of the silane-modified flame retardant and the active sites of the compatibilizer, improving the interfacial bonding with the polymer matrix. In contrast, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, although containing a phosphaphenanthrene ring, has significant steric hindrance in its molecular structure and contains only a single phosphorus-hydrogen bond, resulting in a low density of flame-retardant functional groups and poor compatibility with the matrix and other components. The multifunctional structure of flame retardant ODOPB facilitates polymer char formation during combustion, creating a continuous and dense char layer that blocks oxygen and heat transfer. Simultaneously, the released phosphorus-based flame-retardant gases effectively suppress gas-phase combustion. Benzylphosphonic acid is the next best option, while 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide suffers from insufficient flame-retardant efficiency due to structural limitations. In terms of compatibility, the functional group matching of ODOPB results in more uniform system dispersion and reduced interfacial defects. This reduces scattering loss during light signal transmission, leading to lower light attenuation, and allows for uniform stress distribution within the matrix, improving tensile strength and elongation at break. The uniform microstructure also avoids weak points in pressure resistance. In contrast, the structural defects of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide lead to uneven dispersion, weakening the synergistic flame-retardant effect and causing interfacial stress concentration, resulting in inferior performance across all aspects.

[0071] Comparing Examples 6 and 7 with Comparative Example 3, Example 7 was the best, and Comparative Example 3 was the worst. This may be due to the use of different hydroxyl-containing monomers. The structural differences of the hydroxyl-containing monomers are the core of the performance differentiation. Montmorillonite is a layered aluminosilicate with large interlayer spacing and exchangeable cations. The distribution of hydroxyl groups facilitates deep intercalation of silane coupling agents, forming a thick and stable organic-inorganic interface layer. Hydrotalcite is a layered bimetallic hydroxide with smaller interlayer spacing. Although the hydroxyl groups are uniform, their intercalation effect is limited. Sepiolite has a fibrous structure with irregular layered arrangement; the hydroxyl groups are only distributed on the fiber surface and are unevenly distributed. Mechanistically, the layered structure of montmorillonite synergistically with phosphorus-based flame retardants can catalyze the formation of a dense char layer and provide thermal and oxygen barrier properties, resulting in optimal flame retardancy. Its uniform dispersion reduces interfacial defects, resulting in weak light scattering and low light attenuation. The continuous two-dimensional reinforcing network can efficiently transfer loads, exhibiting outstanding mechanical properties. The dense structure also ensures uniform electric field distribution and stable pressure resistance. Hydrotalcite has slightly inferior intercalation and reinforcement effects, resulting in second-best performance; sepiolite has the worst flame retardancy, light transmission, mechanical properties, and pressure resistance due to weak fiber agglomeration and synergistic effects.

[0072] Comparing Example 7 with Comparative Example 4, Comparative Example 7 is better, while Comparative Example 4 is the worst. The possible reason is that Comparative Example 4 did not add an organic modified flame retardant. The core reason for the superior performance of Example 7 compared to Comparative Example 4 is the lack of synergistic effect from the modified flame retardant. In the modified flame retardant, the phosphorus-based component and layered silicate can form a highly efficient synergistic flame retardant system with magnesium hydroxide and aluminum hydroxide. The phosphorus-based component catalyzes polymer charring, the layered silicate constructs a dense char layer to block heat and oxygen, and magnesium hydroxide and aluminum hydroxide decompose to absorb heat, cool down, and dilute combustible gases. These three components synergistically significantly improve the flame retardant effect. In contrast, Comparative Example 4 lacks a modified flame retardant and relies solely on hydroxides for flame retardancy, resulting in a loose char layer and weak heat and oxygen barrier. Furthermore, the silane-modified flame retardant exhibits good compatibility with the polymer matrix, reducing interfacial defects and light signal scattering loss. Its layered structure also enhances the interfacial bonding between the matrix and filler, improving load transfer efficiency and resulting in superior tensile strength and elongation at break. In addition, modified flame retardants make the sheath material structure more uniform and dense, avoiding micropores and weak points, and ensuring stable pressure resistance. Without modified flame retardants, the material has many defects, which ultimately leads to failure in pressure resistance, fully demonstrating the role of modified flame retardants in improving overall performance.

[0073] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An intelligent early warning layer, characterized in that, include: Optical fiber, resin coated on both sides of the optical fiber, flexible tube threaded onto the optical fiber, aramid fiber rope set on the flexible tube, braided mesh set on the aramid fiber rope, and first flame-retardant sheath material set on the braided mesh. The first flame-retardant sheath layer comprises: 25-35 parts of ethylene-butyl acrylate copolymer, 15-25 parts of ethylene-butene copolymer, 15-25 parts of metallocene-catalyzed linear low-density polyethylene, 5-10 parts of compatibilizer, 120-135 parts of inorganic flame retardant, 15-30 parts of modified flame retardant, 1-2 parts of lubricant, 1-2 parts of antioxidant, and 4-8 parts of color masterbatch; the modified flame retardant comprises a phosphorus-hydrogen bond-containing monomer one, a double bond-containing siloxane, and a hydroxyl-containing monomer two; the mass ratio of the phosphorus-hydrogen bond-containing monomer one, the double bond-containing siloxane, and the hydroxyl-containing monomer two is (0.5-2):1:(1-2).

2. The intelligent early warning layer according to claim 1, characterized in that, The modified flame retardant also includes pentaerythritol phosphate; the mass ratio of the phosphorus-hydrogen bond-containing monomer one, the double bond-containing siloxane, the hydroxyl-containing monomer two, and the pentaerythritol phosphate is (0.5-2):1:(1-2):(0.1-0.5).

3. The intelligent early warning layer according to claim 1, characterized in that, The phosphorus-hydrogen bond-containing monomer is any one of diphenylphosphine oxide, phenylphosphonic acid, and flame retardant ODOPB.

4. The intelligent early warning layer according to claim 1, characterized in that, The hydroxyl-containing monomer II is any one of attapulgite, montmorillonite, and hydrotalcite.

5. The intelligent early warning layer according to claim 1, characterized in that, The inorganic flame retardant is any one or more of magnesium hydroxide and aluminum hydroxide.

6. The intelligent early warning layer according to claim 1, characterized in that, The preparation method of the modified flame retardant includes the following steps: S1. The monomer containing phosphorus hydrogen bonds is heated, an inert gas is introduced, a siloxane containing double bonds is added, heated, stirred, and cooled to room temperature to obtain an intermediate. S2. Dissolve the hydroxyl-containing monomer dipentaerythritol phosphate in a solvent, heat, add the intermediate prepared in step S1, stir, centrifuge, wash, and vacuum dry to obtain the modified flame retardant.

7. The intelligent early warning layer according to claim 6, characterized in that, The heating temperature in step S1 is 140-155℃, and the heating temperature in step S2 is 70-90℃.

8. An intelligent early warning cable, characterized in that, include: The conductor is made of copper wire, the cross-linked polyethylene insulation layer is made of cross-linked polyethylene, the intelligent early warning layer is made of intelligent early warning layer, the filling layer is made of filling rope, the wrapping layer is made of flame retardant tape, and the second flame retardant sheath layer is made of copper wire. The cross-linked polyethylene insulation layer is wrapped around the conductor to form an insulated wire core. The intelligent early warning layer and multiple insulated wire cores are twisted together to form a cable core. The wrapping layer is wrapped around the cable core. The filler is disposed between the insulated wire core and the wrapping layer. The second flame-retardant sheath is extruded onto the wrapping layer.

9. The intelligent early warning cable according to claim 8, characterized in that, The cross-linked polyethylene insulation layer comprises: silane grafting material and catalyst masterbatch; the silane grafting material comprises 40-100 parts polyethylene, 1-3 parts silane cross-linking agent, 0.3-1 parts initiator, and 0.1-2 parts first antioxidant; the catalyst masterbatch comprises 80-100 parts polyethylene, 1-2 parts catalyst, 5-10 parts lubricant, 0.5-1.5 parts second antioxidant, and 0.05-1 parts copper inhibitor.

10. A method for preparing an intelligent early warning cable as described in any one of claims 8-9, characterized in that, Includes the following steps: Step 1: Twist multiple copper wires together and compress them to form a conductor; Step 2: Wrap the cross-linked polyethylene insulation layer over the conductor to obtain an insulated wire core; Step 3: Coat both sides of the optical fiber with UV-cured resin to form a multimode optical fiber. Then, use a flexible hose thread to attach an aramid fiber rope placed longitudinally on the hose, fix it with a braided mesh, extrude the first flame-retardant sheath layer, and form it to prepare the intelligent early warning layer. Step 4: After stranding the intelligent early warning layer and multiple insulated wire cores into a cable core, wrap the wrapping layer around the cable core and fill the space between the insulated wire core and the wrapping layer. Step 5: Extrude the second flame-retardant sheath layer onto the wrapping layer to obtain an intelligent early warning cable.

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