A cable compound for twisted conductors and a process for producing the same

Abstract

The present application relates to the technical field of cable composite material, in particular to a kind of cable composite material for mixed conductor and its production process.It includes inner layer, halogen-free flame-retardant layer and outer layer, the inner layer is low-temperature-resistant modified elastomer, the outer layer is high-temperature-resistant crosslinked polyolefin body, the halogen-free flame-retardant layer includes insulation layer, flame-retardant layer and sheath layer, the insulation layer is nano magnesium hydroxide and zinc borate composite flame retardant, the flame-retardant layer uses ceramicized silicone rubber, and the sheath layer is phosphorus-nitrogen composite flame-retardant system.The high-temperature-resistant crosslinked polyolefin body uses crosslinked polyolefin as matrix, and is prepared by blending nano silicon dioxide and carbon fluoride.Dynamic vulcanization nano composite material is applied to marine cable insulation layer, and corrosion resistance and mechanical properties are realized.

Description

Technical Field

[0001] This invention relates to the field of cable composite materials technology, and more specifically, to a cable composite material for stranded conductors and its manufacturing process. Background Technology

[0002] DCS cables refer to cables used in distributed control systems (DCS). As the core carrier of system signal transmission, they play a crucial role in connecting various system components and transmitting signals and power. Their stability and anti-interference capabilities directly determine the accuracy of industrial control and production safety. However, some cables suffer from weak anti-interference capabilities, high transmission attenuation, and insufficient environmental resistance, making them unsuitable for the demands of high-end industrial applications.

[0003] Currently, the following defects exist: (1) Insufficient anti-interference performance: Signals in DCS systems are easily affected by electromagnetic interference from the surrounding environment, such as electromagnetic fields generated by motors, transformers and other equipment. Traditional DCS cables mostly adopt a single-layer shielding structure, and the shielding efficiency against electromagnetic interference (EMI) and radio frequency interference (RFI) in industrial sites is only 85%-90%, which easily leads to signal distortion and reduced control accuracy. (2) Poor transmission stability: The conductor stranding process is unreasonable, and the signal transmission attenuation reaches 0.15dB / 100m (1kHz), which far exceeds the international advanced level of 0.08dB / 100m, limiting the application of long-distance transmission. (3) Weak environmental adaptability: Existing products can withstand high and low temperatures in the range of -20℃ to 80℃, which cannot meet the usage requirements of extreme working conditions (such as high temperature reaction kettles in chemical plants and low temperature outdoor environments in the north), and the oil resistance and chemical corrosion resistance are insufficient, with a service life of only 3-5 years. (4) Environmental compliance needs to be improved: Some products use halogen-containing sheath materials, which produce toxic gases when burned, which does not meet the environmental flame retardant requirements.

[0004] In the existing technology, irregular conductor structures have the following drawbacks: the outer diameter does not meet the specifications; the matching degree with the terminal block is low, which can easily lead to connection failures; the stranded conductor fill factor is too high, the conductor is too hard, and it is difficult to bend during construction, resulting in low acceptance by low-voltage cable customers; the internal stress is large when bending, which can easily cause the conductor to expand and contract relative to the insulation layer; it can easily cause insulation cracking; the problem of conductor shield embedding is prominent, which affects partial discharge. Summary of the Invention

[0005] This invention provides a cable composite material for stranded conductors and its manufacturing process, applying dynamically vulcanized nanocomposite materials to the insulation layer of marine cables, achieving a synergistic breakthrough in corrosion resistance and mechanical properties.

[0006] In a first aspect, the present invention provides a cable composite material for stranded conductors, comprising an inner layer, a halogen-free flame-retardant layer, and an outer layer. The inner layer is a low-temperature resistant modified elastomer, and the outer layer is a high-temperature resistant cross-linked polyolefin. The halogen-free flame-retardant layer comprises an insulation layer, a flame-retardant layer, and a sheath layer. The insulation layer is a composite flame retardant agent of nano-magnesium hydroxide and zinc borate. The flame-retardant layer is made of ceramicized silicone rubber. The sheath layer is a phosphorus-nitrogen composite flame-retardant system, which is prepared by mixing and compounding black phosphorus crystals with melamine.

[0007] Preferably, the high-temperature resistant cross-linked polyolefin is prepared by blending cross-linked polyolefin as the matrix with nano-silica and fluorinated carbon.

[0008] Preferably, the mass ratio of the nano-silica to the fluorinated carbon is (2~5):(1~2).

[0009] Preferably, the low-temperature resistant modified elastomer is a polyurethane elastomer, which is prepared by chain extension polymerization using oligomeric diol as raw material, introducing 1,5-naphthalene diisocyanate, and using a mixture of 1,4-butanediol and trimethylolpropane as chain extender.

[0010] Preferably, the oligomeric diol is selected from at least one of polytrimethylene ether diol, polytetrahydrofuran ether diol, 3-methyltetrahydrofuran / tetrahydrofuran co-ether diol, caprolactone / tetrahydrofuran co-diol, and polycaprolactone diol.

[0011] Preferably, the mass ratio of the oligomeric diol to the 1,5-naphthalene diisocyanate is (5~8):(1~3), and the mass ratio of the 1,4-butanediol to trimethylolpropane is (1~2):(2~3).

[0012] Preferably, the nano-magnesium hydroxide and zinc borate composite flame retardant is prepared by surface treatment of nano-magnesium hydroxide and zinc borate with a silane coupling agent, and the mass ratio of nano-magnesium hydroxide to zinc borate is (5~7):(2~3).

[0013] Preferably, the mass ratio of the black phosphorus crystals to melamine is (1~2):(3~8).

[0014] Secondly, the present invention provides a manufacturing process for cable composite materials for stranded conductors, comprising the following steps: (1) Preparation of low-temperature resistant modified elastomer for inner layer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 80~90℃, oligomeric diol was added dropwise, the temperature was kept at 80~90℃, and the reaction was carried out for 2~3h to obtain a prepolymer. After the prepolymer was cooled to 80℃, a mixture of 1,4-butanediol and trimethylolpropane was added, and the mixture was vulcanized at 100~120℃ for 1~4h, and then vulcanized at 110~140℃ for 12~24h to obtain the inner layer; (2) Preparation of the outer high temperature resistant cross-linked polyolefin: Nano silica is treated with silane coupling agent, polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant are added, mixed, and melt-blended using a twin-screw extruder, gradually increasing the temperature from 140°C in the feeding section to 170°C~190°C in the extrusion section to obtain the outer layer; (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion, added to deionized water, and dispersed by ultrasonication to obtain a suspension. Under the condition of 70~100℃, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. Extrusion and cooling are then performed to obtain insulating layer. (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed in a two-roll mill. Vulcanizing agent bis(24) or bis(25) is added and mixed again. Then, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0015] Thirdly, the present invention provides an application of a cable composite material, which is used in a cable, specifically in a stranded conductor, wherein the conductor is a copper wire-tinned copper wire hybrid conductor, and the conductor is combined with the cable composite material using electron beam irradiation process parameter dynamic control technology.

[0016] In summary, the present invention has the following beneficial effects: 1. The cable composite material prepared in this invention improves the environmental adaptability of cables. By developing composite insulation materials resistant to salt spray and oil, and optimizing the sheath structure design, the cable can operate stably for a long time in humid, hot, oily, and mechanically vibrating environments, extending its lifespan to over 25 years. For the first time, dynamically vulcanized nanocomposite materials are applied to the insulation layer of marine cables, achieving a synergistic breakthrough in corrosion resistance and mechanical properties; the layered flame-retardant protection system reduces weight by 15% compared to traditional single-layer structures, while simultaneously increasing flame-retardant efficiency by 40%.

[0017] 2. In this invention, the inner layer uses NDI-type polyurethane elastomer, with PTMG as the soft segment. PTMG has an extremely low glass transition temperature (approximately -80°C), which, combined with the strong hydrogen bonding of NDI, allows the cable to maintain excellent flexibility and impact resistance even at temperatures as low as -40°C or even lower, without becoming brittle. This makes it ideal for cold regions or outdoor mobile installations. The outer layer uses cross-linked polyolefin. The cross-linking process transforms linear molecules into a three-dimensional network structure, significantly increasing the heat distortion temperature. This allows for a long-term operating temperature of 105~125°C, short-term tolerance to even higher temperatures, and it does not melt or drip at high temperatures.

[0018] 3. The halogen-free flame-retardant layer in the middle of this invention adopts a triple defense system of insulation + barrier + sheath, which exponentially increases safety compared to traditional single-layer flame retardants. Nano-magnesium hydroxide absorbs a large amount of heat (endothermic effect) and releases water vapor to dilute oxygen when heated and decomposes; zinc borate promotes the formation of a char layer and generates a glassy covering layer at high temperatures, sealing cracks and acting as a self-healing barrier. The ceramicized hard barrier serves as the flame-retardant layer. Under flame erosion, it does not carbonize and collapse like ordinary rubber, but transforms in situ into a hard ceramic skeleton. This ceramic shell effectively supports the cable structure, prevents short circuits in internal conductors, and ensures the integrity of the circuit in a fire. A gas-phase / condensed-phase dual flame-retardant layer serves as the sheath layer. The phosphorus-nitrogen composite system forms a porous expanded char layer on the material surface through an expansion flame-retardant mechanism, isolating heat and oxygen while releasing non-combustible gases, further inhibiting flame spread. The entire system completely eliminates halogenated flame retardants. During combustion, it does not release corrosive and toxic gases such as hydrogen chloride and hydrogen bromide, and has extremely low smoke density.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Attached Figure Description

[0020] Figure 1 This is a physical image of the cable composite material obtained in an embodiment of the present invention used in a cable. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0022] Example Example 1 A manufacturing process for a cable composite material used in stranded conductors includes the following steps: (1) Preparation of the inner layer of low-temperature resistant modified elastomer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 80°C, and oligomeric diol was added dropwise. The reaction was carried out at 80°C for 2 hours to obtain a prepolymer. After cooling the prepolymer to 80°C, a mixture of 1,4-butanediol and trimethylolpropane was added. The mixture was vulcanized at 100°C for 1 hour and then vulcanized at 110°C for 12 hours to obtain the inner layer. The oligomeric diol was selected from polytrimethylene ether glycol. The mass ratio of oligomeric diol to 1,5-naphthalene diisocyanate was 5:1. The mass ratio of 1,4-butanediol to trimethylolpropane was 1:2.

[0023] (2) Preparation of the outer high-temperature resistant cross-linked polyolefin: Nano silica was treated with silane coupling agent, and polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant were added and mixed. The mixture was melt-blended using a twin-screw extruder, and the temperature was gradually increased from 140°C in the feeding section to 170°C in the extrusion section to obtain the outer layer. The mass ratio of nano silica to fluorinated carbon was 2:1.

[0024] (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion and added to deionized water. The suspension is prepared by ultrasonic dispersion. At 70°C, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. The mixture is then extruded and cooled to obtain insulating layer. The mass ratio of nano magnesium hydroxide to zinc borate is 5:2.

[0025] (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed evenly in a two-roll mill. Then, vulcanizing agent bis(24) or bis(25) is added and mixed evenly again. Finally, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. The mass ratio of ceramicized glass powder to fumed silica is 1:2.

[0026] (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. The mass ratio of black phosphorus crystals to melamine is 1:3.

[0027] (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0028] Example 2 A manufacturing process for a cable composite material used in stranded conductors includes the following steps: (1) Preparation of the inner layer of low-temperature resistant modified elastomer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 82°C, and oligomeric diol was added dropwise. The reaction was carried out at 82°C for 2 hours to obtain a prepolymer. After cooling the prepolymer to 80°C, a mixture of 1,4-butanediol and trimethylolpropane was added. The mixture was vulcanized at 105°C for 2 hours and then vulcanized at 120°C for 12 hours to obtain the inner layer. The oligomeric diol was selected from polytetrahydrofuran ether diol. The mass ratio of oligomeric diol to 1,5-naphthalene diisocyanate was 7:1. The mass ratio of 1,4-butanediol to trimethylolpropane was 2:3.

[0029] (2) Preparation of the outer high-temperature resistant cross-linked polyolefin: The nano-silica was treated with a silane coupling agent, and polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant were added and mixed. The mixture was melt-blended using a twin-screw extruder, and the temperature was gradually increased from 140°C in the feeding section to 175°C in the extrusion section to obtain the outer layer. The mass ratio of nano-silica to fluorinated carbon was 3:1.

[0030] (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion and added to deionized water. The suspension is prepared by ultrasonic dispersion. At 75°C, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. The mixture is then extruded and cooled to obtain insulating layer. The mass ratio of nano magnesium hydroxide to zinc borate is 5:3.

[0031] (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed in a two-roll mill. Then, vulcanizing agent bis(24) or bis(25) is added and mixed again. Finally, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. The mass ratio of ceramicized glass powder to fumed silica is 1:3.

[0032] (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. The mass ratio of black phosphorus crystals to melamine is 2:5.

[0033] (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0034] Example 3 A manufacturing process for a cable composite material used in stranded conductors includes the following steps: (1) Preparation of the inner layer of low-temperature resistant modified elastomer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 85°C, and oligomeric diol was added dropwise. The reaction was carried out at 85°C for 3 hours to obtain a prepolymer. After cooling the prepolymer to 80°C, a mixture of 1,4-butanediol and trimethylolpropane was added. The mixture was vulcanized at 110°C for 2 hours and then vulcanized at 130°C for 16 hours to obtain the inner layer. The oligomeric diol was selected from 3-methyltetrahydrofuran / tetrahydrofuran copolyether diol. The mass ratio of oligomeric diol to 1,5-naphthalene diisocyanate was 5:2. The mass ratio of 1,4-butanediol to trimethylolpropane was 1:3.

[0035] (2) Preparation of the outer high-temperature resistant cross-linked polyolefin: Nano silica was treated with silane coupling agent, and polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant were added and mixed. The mixture was melt-blended using a twin-screw extruder, and the temperature was gradually increased from 140°C in the feeding section to 180°C in the extrusion section to obtain the outer layer. The mass ratio of nano silica to fluorinated carbon was 4:1.

[0036] (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion and added to deionized water. The suspension is prepared by ultrasonic dispersion. At 85°C, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. The mixture is then extruded and cooled to obtain insulating layer. The mass ratio of nano magnesium hydroxide to zinc borate is 7:2.

[0037] (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed evenly in a two-roll mill. Then, vulcanizing agent bis(24) or bis(25) is added and mixed evenly again. Finally, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. The mass ratio of ceramicized glass powder to fumed silica is 1:1.

[0038] (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. The mass ratio of black phosphorus crystals to melamine is 2:5.

[0039] (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0040] Example 4 A manufacturing process for a cable composite material used in stranded conductors includes the following steps: (1) Preparation of the inner layer of low-temperature resistant modified elastomer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 90°C, and oligomeric diol was added dropwise. The reaction was carried out at 90°C for 2 hours to obtain a prepolymer. After cooling the prepolymer to 80°C, a mixture of 1,4-butanediol and trimethylolpropane was added. The mixture was vulcanized at 115°C for 3 hours and then vulcanized at 135°C for 18 hours to obtain the inner layer. The oligomeric diol was selected as an adilide / tetrahydrofuran copolymer diol. The mass ratio of oligomeric diol to 1,5-naphthalene diisocyanate was 7:2. The mass ratio of 1,4-butanediol to trimethylolpropane was 2:3.

[0041] (2) Preparation of the outer high-temperature resistant cross-linked polyolefin: Nano silica was treated with silane coupling agent, and polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant were added and mixed. The mixture was melt-blended using a twin-screw extruder, and the temperature was gradually increased from 140°C in the feeding section to 185°C in the extrusion section to obtain the outer layer. The mass ratio of nano silica to fluorinated carbon was 5:1.

[0042] (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion, added to deionized water, and dispersed by ultrasonication to obtain a suspension. At 90°C, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. The mixture is then extruded and cooled to obtain the insulating layer. The mass ratio of nano magnesium hydroxide to zinc borate is 5:2.

[0043] (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed evenly in a two-roll mill. Then, vulcanizing agent bis(24) or bis(25) is added and mixed evenly again. Finally, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. The mass ratio of ceramicized glass powder to fumed silica is 1:2.

[0044] (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. The mass ratio of black phosphorus crystals to melamine is 2:5.

[0045] (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0046] Example 5 A manufacturing process for a cable composite material used in stranded conductors includes the following steps: (1) Preparation of the inner layer of low-temperature resistant modified elastomer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 90°C, and oligomeric diol was added dropwise. The reaction was carried out at 90°C for 3 hours to obtain a prepolymer. After cooling the prepolymer to 80°C, a mixture of 1,4-butanediol and trimethylolpropane was added. The mixture was vulcanized at 120°C for 4 hours and then vulcanized at 140°C for 24 hours to obtain the inner layer. The oligomeric diol was selected from polycaprolactone diol. The mass ratio of oligomeric diol to 1,5-naphthalene diisocyanate was 8:3. The mass ratio of 1,4-butanediol to trimethylolpropane was 2:3.

[0047] (2) Preparation of the outer high-temperature resistant cross-linked polyolefin: Nano silica was treated with silane coupling agent, and polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant were added and mixed. The mixture was melt-blended using a twin-screw extruder, and the temperature was gradually increased from 140°C in the feeding section to 190°C in the extrusion section to obtain the outer layer. The mass ratio of nano silica to fluorinated carbon was 5:2.

[0048] (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion and added to deionized water. The suspension is prepared by ultrasonic dispersion. At 100°C, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. The mixture is then extruded and cooled to obtain insulating layer. The mass ratio of nano magnesium hydroxide to zinc borate is 7:3.

[0049] (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and fumed silica are added and fully mixed evenly in a two-roll mill. Then, vulcanizing agent bis(24) or bis(25) is added and mixed evenly again. Finally, the mixture is vulcanized at high temperature through a flat vulcanizing machine to obtain the flame retardant layer. The mass ratio of ceramicized glass powder to fumed silica is 1:4.

[0050] (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. The mass ratio of black phosphorus crystals to melamine is 1:8.

[0051] (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

[0052] Comparative Example 1 The difference from the example is that no inner layer of low-temperature resistant modified elastomer was added.

[0053] Comparative Example 2 The difference from the example is that no outer layer of high-temperature resistant cross-linked polyolefin was added.

[0054] Comparative Example 3 The difference from the embodiment is that no insulating layer was added.

[0055] Comparative Example 4 The difference from the embodiment is that no sheath layer was added.

[0056] Outer layer performance testing: Salt spray corrosion resistance (no cracking after ≥3000h salt spray test) and oil resistance (volume expansion rate ≤10% under ASTM D471 standard), breaking through the aging bottleneck of traditional PVC or EPR materials in humid and oily environments. Achieving a microscopic interpenetrating network structure of the elastomer and plastic phases, giving the material both high flexibility (bending radius ≤4D) and resistance to mechanical fatigue (vibration test ≥10). 7 (No damage).

[0057] Inner and outer layer testing: The cable maintains a dielectric strength of ≥20kV / mm and a volume resistivity of ≥1×10⁻⁶ within the temperature range of -40℃ to 105℃. 15 Ω·cm.

[0058] Halogen-free flame retardant layer testing: The cable passes the IEC60332-3A class bundled burning test, with smoke density ≤40% (ISO5659-2 standard) and corrosive gas pH value ≥4.5, which is better than the IMO regulatory requirements.

[0059] Develop a copper-tinned copper wire hybrid conductor, combined with a double-layer shielding structure, with an inner layer of aluminum foil longitudinal wrapping and an outer layer of tinned copper wire braiding, achieving a coverage rate of ≥90% and a cable transmission loss of ≤0.5dB / m (frequency 1GHz), meeting the signal integrity requirements of ship radar and navigation systems.

[0060] Performance test items and test methods: (1) Tensile strength: using a universal testing machine; operating conditions: tensile rate 10 mm / min, room temperature environment; (2) Elongation at break: using a universal testing machine; execution conditions: obtained simultaneously with tensile strength; (3) Impact strength: simple supported beam impact test; execution conditions: tensile rate using standard specimens, room temperature environment.

[0061] Table 1 Performance Test Results

[0062] As shown in Table 1, the cable composite material prepared in Example 1 has good mechanical properties, indicating that the inner NDI polyurethane provides good elasticity, the rigid filler in the middle layer restricts deformation, and the cross-linked structure in the outer layer restricts plastic flow. Through the precise complementarity of the functions of each layer, the problem that traditional cables cannot simultaneously achieve low temperature resistance, high temperature resistance, high flame retardancy, and high mechanical strength is solved.

[0063] The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cable composite material for stranded conductors, characterized in that, It includes an inner layer, a halogen-free flame-retardant layer, and an outer layer. The inner layer is a low-temperature resistant modified elastomer, and the outer layer is a high-temperature resistant cross-linked polyolefin. The halogen-free flame-retardant layer includes an insulating layer, a flame-retardant layer, and a sheath layer. The insulating layer is a composite flame retardant of nano-magnesium hydroxide and zinc borate. The flame-retardant layer is made of ceramicized silicone rubber. The sheath layer is a phosphorus-nitrogen composite flame-retardant system, which is prepared by mixing and compounding black phosphorus crystals with melamine.

2. The cable composite material for stranded conductors according to claim 1, characterized in that, The high-temperature resistant cross-linked polyolefin is prepared by blending cross-linked polyolefin as the matrix with nano-silica and fluorinated carbon.

3. The cable composite material for stranded conductors according to claim 2, characterized in that, The mass ratio of the nano-silica to fluorinated carbon is (2~5):(1~2).

4. The cable composite material for stranded conductors according to claim 1, characterized in that, The low-temperature resistant modified elastomer is a polyurethane elastomer, which is prepared by chain extension polymerization using oligomeric diol as raw material, introducing 1,5-naphthalene diisocyanate, and using a mixture of 1,4-butanediol and trimethylolpropane as chain extender.

5. The cable composite material for stranded conductors according to claim 4, characterized in that, The oligomeric diol is selected from at least one of polytrimethylene ether diol, polytetrahydrofuran ether diol, 3-methyltetrahydrofuran / tetrahydrofuran co-ether diol, caprolactone / tetrahydrofuran co-diol, and polycaprolactone diol.

6. The cable composite material for stranded conductors according to claim 4, characterized in that, The mass ratio of the oligomeric diol to the 1,5-naphthalene diisocyanate is (5~8):(1~3), and the mass ratio of the 1,4-butanediol to trimethylolpropane is (1~2):(2~3).

7. The cable composite material for stranded conductors according to claim 1, characterized in that, The nano-magnesium hydroxide and zinc borate composite flame retardant is prepared by surface treatment of nano-magnesium hydroxide and zinc borate with a silane coupling agent, and the mass ratio of nano-magnesium hydroxide to zinc borate is (5~7):(2~3).

8. The cable composite material for stranded conductors according to claim 1, characterized in that, The mass ratio of black phosphorus crystals to melamine is (1~2):(3~8).

9. The manufacturing process of the cable composite material for stranded conductors according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Preparation of low-temperature resistant modified elastomer for inner layer: Under dry nitrogen protection, 1,5-naphthalene diisocyanate was added to the reactor, the temperature was raised to 80~90℃, oligomeric diol was added dropwise, the temperature was kept at 80~90℃, and the reaction was carried out for 2~3h to obtain a prepolymer. After the prepolymer was cooled to 80℃, a mixture of 1,4-butanediol and trimethylolpropane was added, and the mixture was vulcanized at 100~120℃ for 1~4h, and then vulcanized at 110~140℃ for 12~24h to obtain the inner layer; (2) Preparation of the outer high temperature resistant cross-linked polyolefin: Nano silica is treated with silane coupling agent, polyethylene matrix, fluorinated carbon, cross-linking agent dicumyl peroxide and antioxidant are added, mixed, and melt-blended using a twin-screw extruder, gradually increasing the temperature from 140°C in the feeding section to 170°C~190°C in the extrusion section to obtain the outer layer; (3) Preparation of insulating layer: Nano magnesium hydroxide and zinc borate powder are mixed in proportion, added to deionized water, and dispersed by ultrasonication to obtain a suspension. Under the condition of 70~100℃, silane coupling agent solution is slowly added dropwise to the suspension, mixed, filtered and dried, and melt-blended with matrix resin polyolefin, synergist pentaerythritol and antioxidant. Extrusion and cooling are then performed to obtain insulating layer. (4) Preparation of flame retardant layer: Using silicone rubber as the matrix, ceramicized glass powder and supplementary fumed silica are added and fully mixed evenly in a two-roll mill. Vulcanizing agent bis(24) or bis(25) is added and mixed evenly again. Then, the flame retardant layer is obtained by high-temperature vulcanization through a flat vulcanizing machine. (5) Preparation of the sheath layer: Under an inert atmosphere, black phosphorus crystals and melamine are ball-milled to obtain amino-grafted phosphorene nanosheets. Melamine and formaldehyde are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer. The two are mixed and dispersed, filtered and dried to obtain the sheath layer. (6) The prepared low-temperature resistant modified elastomer material is extruded into an inner layer through an extruder. An insulation layer is extruded on the inner layer. The prepared ceramicized silicone rubber is tightly wrapped around the outside of the insulation layer in the form of a wrapping tape. A sheath layer is extruded on the ceramicized silicone rubber flame retardant layer. A high-temperature resistant cross-linked polyolefin is extruded on the outermost layer to obtain a cable composite material for stranded conductors.

10. The application of the cable composite material according to any one of claims 1 to 8, characterized in that, The cable composite material is used in the cable, specifically in the stranded conductor, which is a copper wire-tinned copper wire hybrid conductor. The conductor is combined with the cable composite material using dynamic control technology of electron beam irradiation process parameters.

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