An electromagnetic radiation resistant flame-retardant control cable and a method for manufacturing the same

Abstract

This invention relates to an electromagnetic radiation-resistant flame-retardant control cable and its preparation method, belonging to the field of control cable technology. The control cable includes a core, a metal foil, and a modified sheath. The modified sheath uses PVC resin as a base material and adds a reinforcing agent of 10-15 phr. The reinforcing agent is prepared via a four-step process: N-phenyl-p-phenylenediamine reacts with trifluoroacetic anhydride to obtain a passivated matrix, which is then oxidized with 4,4-diaminodiphenylamine to obtain a tetramer intermediate. This intermediate is then protected by alkali desorption to obtain a terminal amino tetramer monomer, which is finally polymerized with thiodiacetic acid to obtain the final product. This agent chelates onto the surface of the metal foil through a thioamide structure, forming an aniline tetramer enrichment layer. This imparts excellent bending resistance, self-healing shielding performance, and a synergistic effect of high-temperature charring and flame retardancy to the cable, effectively solving the problems of easy bending and damage to the metal foil shielding layer and shielding failure under continuous ignition.

Description

Technical Field

[0001] This invention belongs to the field of control cable technology, specifically, it relates to an electromagnetic radiation resistant flame-retardant control cable and its preparation method. Background Technology

[0002] Electromagnetic radiation resistant cables, by incorporating an internal metallic shielding layer, utilize the reflection, absorption, and skin effect of electromagnetic waves to effectively prevent internal signals from radiating outwards and interfering with other equipment. Simultaneously, they prevent external electromagnetic interference from intruding into internal signal transmission, making them a key component for ensuring the electromagnetic compatibility of electronic equipment. The shielding layer is the core component determining the cable's anti-interference capability. Based on the structural form of the shielding layer, existing technologies mainly classify them into three types.

[0003] The first type is the braided shielding layer, which consists of fine metal wires (usually tinned copper wire or bare copper wire) woven into a mesh structure on the outside of the insulated core. Braided shielding layers have excellent mechanical strength and bending resistance. However, due to the inherent gaps between the metal wires, the braided layer cannot achieve 100% coverage. In high-frequency electromagnetic interference environments, electromagnetic waves can leak through these gaps, thus the shielding effect has inherent limitations.

[0004] The second type is the spiral-wound shielding layer, which consists of metal wires wound in a spiral shape around the insulated core. Spiral-wound shielding layers offer excellent flexibility and bend life, are easy to terminate, and are most efficient when providing low-frequency protection. However, their main drawback is that the shielding effect is directional, and the shielding characteristics change when bent. High-frequency interference suppression is significantly insufficient. After the cable undergoes multiple bends, the spiral-wound metal wires are prone to loosening and separation, leading to a loss of shielding effectiveness. Furthermore, similar to the first type of shielding layer, the manufacturing process is more complex and the processing is relatively cumbersome.

[0005] The third type is the metal foil shielding layer, which typically uses aluminum or copper foil spirally wound or longitudinally wrapped around the cable core. Metal foil shielding layers can achieve 100% seamless coverage and have excellent shielding effects against high-frequency interference above 100MHz. However, metal foil shielding layers have significant drawbacks in terms of bending resistance: the metal foil thickness is usually only 9 to 50 micrometers. When bent, the extremely thin foil is compressed and stacked on the inside, and stretched and torn on the outside. After repeated bending, the metal foil breaks due to metal fatigue, disrupting the shielding continuity and resulting in a loss of high shielding effectiveness. Furthermore, due to the limited mechanical properties of the metal foil itself, once the cable is bent during installation and use, the shielding layer is highly susceptible to irreversible damage.

[0006] In summary, while braided and spiral shielding layers have good flexibility and bend resistance, they cannot achieve 100% coverage and are difficult to meet the electromagnetic compatibility requirements under high-frequency or high-shield conditions. Although metal foil shielding layers can provide complete and fully enclosed shielding, their bend resistance is extremely poor, and they are very easy to break and fail due to bending during cable laying and use.

[0007] Furthermore, all three types of shielding layers mentioned above are highly susceptible to damage from external forces due to their small structural dimensions, necessitating mechanical protection from the outer sheath. Therefore, the mechanical properties of the sheath directly determine the stability of the control cable's shielding effect. Simultaneously, control cables in industrial control, rail transportation, and data centers often face fire safety hazards, creating an urgent need for flame-retardant properties in the sheath material. Existing technologies typically introduce halogen-based or phosphorus-nitrogen-based flame retardants into the sheath material to impart flame-retardant properties. However, under sustained high-temperature ignition conditions, conventional flame-retardant sheath materials will carbonize or form expanding, porous carbides. These carbonized layers have low structural strength and are prone to cracking and detachment under flame impact, making it difficult to provide continuous and effective thermal protection to the inner metal foil shielding layer. Once the shielding layer is damaged due to high-temperature oxidation or flame erosion, the entire cable's electromagnetic radiation resistance will drastically decrease, potentially leading to communication interruptions and electromagnetic compatibility failures.

[0008] Therefore, how to effectively solve the problem of metal foil bending and damage while maintaining the high shielding efficiency of the metal foil shielding layer, and ensure that the sheath can provide continuous and effective thermal protection for the shielding layer in high-temperature fire environments, while achieving synergistic enhancement of flame retardancy and shielding functions, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide an electromagnetic radiation resistant flame-retardant control cable and its preparation method.

[0010] The objective of this invention can be achieved through the following technical solutions: An electromagnetic radiation resistant flame-retardant control cable includes at least: a conductor, a metal foil wrapped around the outside of the conductor, and a modified sheath extruded onto the surface of the metal foil; the modified sheath comprises the following components by weight: 100 parts PVC resin, 20-25 parts plasticizer, 10-15 parts reinforcing agent, 6-9 parts flame retardant, 3.5-5 parts heat stabilizer, 0.8-1.2 parts antioxidant, 2-3 parts lubricant, and 12-15 parts filler.

[0011] The preparation method of the strengthening agent is as follows: A1. Synthesis of passivation matrix: N-phenyl-p-phenylenediamine and anhydrous acetone were premixed and slowly added under an ice-water bath and dry nitrogen atmosphere. After that, the ice-water bath was removed and the reaction continued for 1.5-2 hours. The trifluoroacetic anhydride reacted with the terminal active primary amine of N-phenyl-p-phenylenediamine to form trifluoroacetyl end protection. The solvent acetone was removed by rotary evaporation, and then deionized water was added to wash and the aqueous phase was separated to remove the byproduct mainly trifluoroacetic acid. After vacuum drying, the passivation matrix was obtained. Preferably, in the synthesis of the passivation matrix, the molar ratio of N-phenyl-p-phenylenediamine to trifluoroacetic anhydride is 1:1-1.2. The excess trifluoroacetic anhydride ensures that the amino group of N-phenyl-p-phenylenediamine is effectively passivated, avoiding self-polymerization in subsequent reactions.

[0012] A2. Synthesis of the tetramer intermediate: The passivated matrix, 4,4-diaminodiphenylamine, concentrated hydrochloric acid and DMF were premixed, cooled in an ice-water bath and then slowly added to an ammonium persulfate solution. After that, the ice-water bath was removed and the process continued for 2-3 hours. Under the catalysis of concentrated hydrochloric acid and ammonium persulfate, the passivated matrix and 4,4-diaminodiphenylamine were oxidatively polymerized to form a tetraphenylamine-containing condensate. The reaction solution was poured into saturated brine, the precipitate was collected and washed with deionized water to obtain the tetramer intermediate. Furthermore, in the synthesis of the tetramer intermediate, the molar ratio of the passivating matrix to 4,4-diaminodiphenylamine is 1:1.

[0013] A3. Synthesis of terminal amino tetramer monomer: The tetramer intermediate and alkaline ethanol aqueous solution are mixed and hydrolyzed by stirring at a water bath temperature of 40-55℃ for 6-8 hours. The terminal trifluoroacetyl structure of the tetramer intermediate is hydrolyzed to form a diamino terminus. After separating the aqueous phase, the mixture is dried to obtain the terminal amino tetramer monomer. Preferably, the solid-liquid mass ratio of the tetramer intermediate to the alkaline ethanol aqueous solution is 1:8-12, and the pH of the alkaline ethanol aqueous solution is 13-14.

[0014] A4. Synthesis of strengthening agent: The terminal amino tetramer monomer, thiodiacetic acid and DMF are premixed, and then EDC·HCl and HOBt are added and mixed. Under nitrogen protection, the mixture is heated to 80-100℃ and stirred for 20-25h. The terminal amino tetramer monomer and thiodiacetic acid polymerize to form an amide polymer. Most of the DMF is removed by rotary evaporation under reduced pressure. Deionized water is added to precipitate the precipitate. After drying, the strengthening agent is obtained. Furthermore, the molar ratio of the terminal amino tetramer monomer to thiodiacetic acid is 1:1.03-1.05.

[0015] A method for preparing an electromagnetic radiation resistant flame-retardant control cable includes the following steps: S1. Melt blending: Mix the components used for modifying the sheath, and granulate the mixture by melt blending extrusion using a twin-screw extruder to obtain a composite masterbatch; S2, Metal foil wrapping: The wire cores are laid out and twisted together by a cabling machine, and then metal foil is wrapped around the surface; S3. Modified sheath extrusion: The composite masterbatch is melted and extruded through a single screw extruder and coated onto the surface of the wrapped metal foil. After cooling and molding, the control cable is obtained.

[0016] Preferably, the wrapping tension of the metal foil is 4-6N. The relatively low wrapping tension allows the metal foil to have a certain degree of relaxation, which is beneficial for the bonding of reinforcing agents and the recovery after bending.

[0017] The beneficial effects of this invention are: This invention provides an electromagnetic radiation-resistant flame-retardant control cable and its preparation method. By introducing a self-developed thioamide-terminated aniline tetramer reinforcing agent into the PVC-based sheath material, and utilizing the multifunctional properties of this agent, a synergistic mechanism is established between the metal foil shielding layer and the sheath at three levels: interface chelation reinforcement, conductive bridging reconstruction, and high-temperature charring protection. This overcomes the bottleneck problems in the prior art where the metal foil shielding layer is easily damaged by bending and the shielding effectiveness rapidly decays under continuous high-temperature ignition.

[0018] From a chemical structure perspective, the reinforcing agent of this invention is a low molecular weight block polymer whose molecular structure contains two key functional units: an aniline tetramer segment and a thioamide linking structure. The aniline tetramer, as an oligomer model of polyaniline, retains the conductivity of polyaniline. The sulfur atom in the thioamide structure possesses a lone pair of electrons, which can form coordinate bonds with empty orbitals on the surfaces of metals such as aluminum and copper, resulting in a strong chelating effect. Based on the above structural features, the beneficial effects of this invention are specifically reflected in the following aspects: First, the interfacial chelation enrichment effect endows the metal foil shielding layer with bending resistance and self-healing ability. During the sheath melt extrusion process, the thioamide structure in the reinforcing agent undergoes strong chelation with the aluminum atoms on the aluminum foil surface, causing the reinforcing agent molecules to be directionally adsorbed and enriched on the metal foil surface. This chelation brings about two effects: on the one hand, the benzene ring structure enriched on the aluminum foil surface forms a local rigid reinforcement layer through π-π stacking, improving the deformation resistance of the aluminum foil surface. When the cable is bent, this reinforcement layer can resist excessive deformation caused by external force, effectively reducing the compression stacking and tensile tearing of the aluminum foil; on the other hand, the chelation sites act as "molecular anchor points," firmly anchoring the reinforcing agent molecules to the aluminum foil surface. Even if the aluminum foil experiences local tearing and fragmentation during severe bending, these fragments still remain connected to the reinforcing agent through chelate bonds. When the bending stress is relieved and the cable shape is restored, the aluminum foil fragments anchored on the inner wall of the sheath return to their original position with the elastic retraction of the sheath, and re-spread to form a continuous covering structure. This "controlled breakage-anchoring repaving" mechanism fundamentally solves the inherent problem that traditional metal foil shielding layers cannot be restored after bending and damage.

[0019] Second, the conductive network reconstruction effect establishes electrical continuity between broken fragments. Reinforcing agent molecules enriched on the metal foil surface intertwine to form a three-dimensional conductive network through π-π stacking interactions between aniline tetramer segments. This conductive network is distributed on the aluminum foil surface and between fragments. When the aluminum foil breaks due to bending, these fragments might otherwise lose electrical contact, but the presence of the conductive network allows current to still be transmitted between different fragments through the aniline tetramer network, forming a bypass conductive path that bypasses the fracture region. In other words, the reinforcing agent constructs a "redundant conductive layer" on the metal foil surface. Even if the aluminum foil itself experiences physical breakage, this conductive layer can still maintain the electrical continuity of the shielding layer, ensuring that the electromagnetic shielding function does not fail due to localized damage to the aluminum foil. This function is fundamentally different from the traditional approach that relies solely on the conductivity of the aluminum foil itself: in traditional solutions, the conductivity of the shielding layer depends entirely on the integrity of the metal foil itself, and failure occurs once it breaks; however, this invention, through a dual-pathway design of "metal foil conductivity + redundant conductivity of the conductive polymer network," transforms the failure mode of the shielding layer from "sudden failure" to "gradual decay," significantly improving the reliability of the shielding system.

[0020] Third, the high-temperature densification and charring effect achieves synergistic protection of flame retardancy and shielding. The reinforcing additive of this invention not only functions at room temperature but also exhibits unique functional characteristics under sustained ignition in a fire. The aniline tetramers enriched on the surface of the metal foil through chelation are rich in aromatic ring structures. Under the action of high-temperature flames, these aromatic ring structures undergo thermal cross-linking and carbonization, forming a dense and uniform carbonized layer in situ on the aluminum foil surface. Unlike the expanded and loose carbonized layer formed during the combustion of conventional flame-retardant sheathing materials, the carbonized layer of this invention has the following significant advantages: First, the high thermal stability of the benzene ring structure ensures that the carbonized layer remains structurally intact at high temperatures and is not prone to cracking and peeling; second, the density of the carbonized layer is much higher than that of conventional expanded carbon layers, which can more effectively block the transfer of flame heat to the aluminum foil while isolating oxygen to prevent high-temperature oxidation of the aluminum foil; third, since the carbonized layer is generated in situ on the surface of the aluminum foil, its bonding force with the aluminum foil is stronger than the physical contact between the carbonized layer and the shielding layer of conventional sheathing, and it is not easily separated due to thermal stress or mechanical vibration. Therefore, the modified sheath of the present invention can provide continuous and reliable protection for the metal foil during the continuous ignition process, ensuring that the shielding layer can still work normally after the sheath is carbonized, thereby maintaining the communication stability and electromagnetic compatibility of the control cable in a fire environment.

[0021] In summary, the three functional levels of the reinforcing agent in this invention—interfacial chelation enrichment, conductive network reconstruction, and high-temperature densification and carbonization—are not isolated, single effects, but rather achieve organic synergy through a common chemical structural basis (thioamide chelation anchoring + aniline tetramer π-π stacking): the chelation action anchors the reinforcing agent to the aluminum foil surface, providing a spatial positioning basis for the formation of the conductive network and the in-situ generation of the carbonized layer; the conductive network ensures the continuity of shielding after bending at room temperature, and serves as a precursor structure for the carbonized layer at high temperatures; while the formation of the carbonized layer further consolidates the mechanical connection and electrical contact between aluminum foil fragments. Compared with existing technologies that compensate for aluminum foil defects by adding a braided shielding layer or using a multi-layer composite shielding structure, the single-layer modified sheath design of this invention solves the two major technical problems of bending damage and high-temperature failure without significantly increasing the cable's outer diameter and weight, demonstrating significant economic benefits and market promotion value. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] To facilitate understanding of the technical solutions during the implementation of this invention, the relevant experimental material information is disclosed as follows: For the wire core, taking a 4-core control cable as an example, a single-core control wire is used; the metal foil is 0.05mm aluminum foil; the PVC resin is SG-3 general-purpose resin; the plasticizer (20-25 parts) is industrial-grade dioctyl phthalate; the flame retardant is M1416 high-efficiency phosphorus-nitrogen flame retardant; the heat stabilizer is HYCZ-106 calcium-zinc composite heat stabilizer; the antioxidant is antioxidant 1010 and antioxidant 168 mixed in equal weight ratio; the lubricant is industrial-grade calcium stearate; and the filler is 300-mesh light calcium carbonate powder.

[0024] Example 1: Preparation of an electromagnetic radiation-resistant flame-retardant control cable. The specific implementation method is as follows: I. Preparation of fortifying agents A1. Synthesis of the passivation matrix: N-phenyl-p-phenylenediamine and anhydrous acetone were added and premixed by stirring. The mixture was cooled to 5°C using an ice-water bath while dry nitrogen gas was introduced until a stable gas flow was observed. Trifluoroacetic anhydride was slowly added. After complete addition, the ice-water bath was removed and the reaction was stirred for 2 hours. The raw materials for the reaction were: 0.1 mol N-phenyl-p-phenylenediamine, 0.1 mol trifluoroacetic anhydride, and 300 mL anhydrous acetone. Finally, the solvent acetone was removed by rotary evaporation, and deionized water was added to wash the mixture and separate the aqueous phase to remove the byproduct mainly composed of trifluoroacetic acid. After vacuum drying, the passivation matrix was obtained.

[0025] A2. Synthesis of the tetramer intermediate: The passivated matrix, 4,4-diaminodiphenylamine, concentrated hydrochloric acid and DMF were added and stirred for premixing. The mixture was cooled in an ice-water bath. When the temperature reached 10°C, ammonium persulfate solution was slowly added. After the addition was complete, the ice-water bath was removed and the reaction was stirred for 3 hours. The raw materials for the reaction were: 0.1 mol passivated matrix, 0.1 mol 4,4-diaminodiphenylamine, 15 g ammonium persulfate (prepared into a saturated aqueous solution with deionized water), 8 mL concentrated hydrochloric acid, and 220 mL DMF (N,N-dimethylformamide). Finally, the reaction solution was poured into saturated brine, the precipitate was collected and washed with deionized water to obtain the tetramer intermediate.

[0026] A3. Synthesis of terminal amino tetramer monomer: Prepare a 30% ethanol aqueous solution, alkalize it with potassium hydroxide to control the pH value to 13, and then add the prepared tetramer intermediate to the alkaline ethanol aqueous solution at a solid-liquid mass ratio of 1:8. Heat the solution in a water bath to 40°C and stir for 8 hours to hydrolyze it. Finally, centrifuge to remove the aqueous phase and dry it to obtain the terminal amino tetramer monomer.

[0027] A4. Synthesis of the strengthening agent: A terminal amino tetramer monomer, thiodiacetic acid, and DMF were added and premixed. Then, EDC·HCl (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and HOBt (1-hydroxybenzotriazole) were added and mixed. Nitrogen gas was introduced for protection, and the mixture was heated to 80℃ and stirred for 25 hours. The reactants were: 0.1 mol terminal amino tetramer monomer, 0.103 mol thiodiacetic acid, 5.5 g EDC·HCl, 3 g HOBt, and 450 mL DMF. Most of the DMF was removed by rotary evaporation under reduced pressure. After cooling, deionized water was added to precipitate the precipitate. The precipitate was dried to obtain the strengthening agent.

[0028] II. Preparation of Electromagnetic Radiation Resistant and Flame-Retardant Control Cables S1. Preparation of composite masterbatch: Take 100 parts of PVC resin, 25 parts of plasticizer, 10 parts of reinforcing agent, 9 parts of flame retardant, 3.5 parts of heat stabilizer, 0.8 parts of antioxidant, 3 parts of lubricant and 15 parts of filler. Add each component raw material to a high-speed mixer and mix at 600 rpm for 5 minutes. Feed the mixture into a twin-screw extruder (ceramic liner), control the temperature of the compression section to 200℃, melt-extrude the mixture, and obtain the composite masterbatch through traction, cooling and pelletizing.

[0029] S2. Metal Foil Wrapping: The wire cores are laid out and twisted together by a cabling machine. The aluminum foil is unwound by a wrapping machine, and the wrapping tension of the aluminum foil is controlled at 4N. The aluminum foil is then wrapped around the wire cores.

[0030] S3. Modified sheath extrusion: The composite masterbatch is melted and extruded through a single screw extruder (ceramic liner) with the compression section temperature controlled at 180℃. The extruded material is then wrapped around the surface of the metal foil through the die head. During extrusion, the pressure of the melt in the die head is controlled at 8MPa. After cooling and forming, the control cable is obtained.

[0031] Example 2: Preparation of an electromagnetic radiation-resistant flame-retardant control cable. The specific implementation method is as follows: I. Preparation of fortifying agents A1. Synthesis of the passivation matrix: N-phenyl-p-phenylenediamine and anhydrous acetone were added and premixed by stirring. The mixture was cooled to 5°C using an ice-water bath while dry nitrogen gas was introduced until a stable gas flow was observed. Trifluoroacetic anhydride was slowly added. After complete addition, the ice-water bath was removed and the reaction was stirred for 1.5 h. The raw materials for the reaction were: 0.1 mol N-phenyl-p-phenylenediamine, 0.12 mol trifluoroacetic anhydride, and 350 mL anhydrous acetone. Finally, the solvent acetone was removed by rotary evaporation, and deionized water was added to wash the mixture and separate the aqueous phase to remove the byproduct mainly composed of trifluoroacetic acid. After vacuum drying, the passivation matrix was obtained.

[0032] A2. Synthesis of the tetramer intermediate: The passivated matrix, 4,4-diaminodiphenylamine, concentrated hydrochloric acid, and DMF were added and premixed by stirring. The mixture was cooled in an ice-water bath. When the temperature reached 10°C, ammonium persulfate solution was slowly added. After the solution was completely added, the ice-water bath was removed and the reaction was stirred for another 2 hours. The raw materials for the reaction were: 0.1 mol of passivated matrix, 0.1 mol of 4,4-diaminodiphenylamine, 20 g of ammonium persulfate (prepared into a saturated aqueous solution with deionized water), 12 mL of concentrated hydrochloric acid, and 300 mL of DMF. Finally, the reaction solution was poured into saturated brine, the precipitate was collected, and washed with deionized water to obtain the tetramer intermediate.

[0033] A3. Synthesis of terminal amino tetramer monomer: Prepare a 30% ethanol aqueous solution, alkalize it with potassium hydroxide to control the pH value to 14, and then add the prepared tetramer intermediate to the alkaline ethanol aqueous solution at a solid-liquid mass ratio of 1:12. Heat the solution in a water bath to 55°C and stir for 6 hours to hydrolyze it. Finally, centrifuge to remove the aqueous phase and dry it to obtain the terminal amino tetramer monomer.

[0034] A4. Synthesis of the strengthening agent: Terminal amino tetramer monomer, thiodiacetic acid and DMF were added and stirred for premixing. Then EDC·HCl and HOBt were added and mixed. Nitrogen gas was introduced for protection, and the mixture was heated to 100℃ and stirred for 20h. The raw materials for the reaction were: 0.1mol terminal amino tetramer monomer, 0.105mol thiodiacetic acid, 7g EDC·HCl, 4g HOBt, and 550mL DMF. Finally, most of the DMF was removed by rotary evaporation under reduced pressure. After cooling, deionized water was added to precipitate the precipitate. The precipitate was dried to obtain the strengthening agent.

[0035] II. Preparation of Electromagnetic Radiation Resistant and Flame-Retardant Control Cables S1. Preparation of composite masterbatch: Take 100 parts of PVC resin, 20 parts of plasticizer, 15 parts of reinforcing agent, 6 parts of flame retardant, 5 parts of heat stabilizer, 1.2 parts of antioxidant, 2 parts of lubricant and 12 parts of filler. Add each component raw material to a high-speed mixer and mix at 600 rpm for 5 minutes. Feed the mixture into a twin-screw extruder (ceramic liner), control the temperature of the compression section to 210℃, melt-extrude the mixture, and obtain the composite masterbatch through traction, cooling and pelletizing.

[0036] S2. Metal Foil Wrapping: The wire cores are laid out and twisted together by a cabling machine. The aluminum foil is unwound by a wrapping machine, and the wrapping tension of the aluminum foil is controlled to be 6N. The aluminum foil is then wrapped around the wire cores.

[0037] S3. Modified sheath extrusion: The composite masterbatch is melted and extruded through a single screw extruder (ceramic liner) with the compression section temperature controlled at 190℃. The extruded material is then wrapped around the surface of the wrapped metal foil through the die head. During extrusion, the pressure of the melt in the die head is controlled at 10MPa. After cooling and forming, the control cable is obtained.

[0038] Example 3: Preparation of an electromagnetic radiation-resistant flame-retardant control cable. The specific implementation method is as follows: I. Preparation of fortifying agents A1. Synthesis of the passivation matrix: N-phenyl-p-phenylenediamine and anhydrous acetone were added and premixed by stirring. The mixture was cooled to 5°C using an ice-water bath while dry nitrogen gas was introduced until a stable gas flow was observed. Trifluoroacetic anhydride was slowly added. After complete addition, the ice-water bath was removed and the reaction was stirred for 1.8 h. The raw materials for the reaction were: 0.1 mol N-phenyl-p-phenylenediamine, 0.11 mol trifluoroacetic anhydride, and 320 mL anhydrous acetone. Finally, the solvent acetone was removed by rotary evaporation, and deionized water was added to wash the mixture and separate the aqueous phase to remove the byproduct mainly composed of trifluoroacetic acid. After vacuum drying, the passivation matrix was obtained.

[0039] A2. Synthesis of the tetramer intermediate: Passivated matrix, 4,4-diaminodiphenylamine, concentrated hydrochloric acid and DMF were added and premixed by stirring. The mixture was cooled in an ice-water bath. When the temperature reached 10°C, ammonium persulfate solution was slowly added. After the addition was complete, the ice-water bath was removed and the reaction was stirred for 2.5 h. The raw materials for the reaction were: 0.1 mol of passivated matrix, 0.1 mol of 4,4-diaminodiphenylamine, 17 g of ammonium persulfate (prepared into a saturated aqueous solution with deionized water), 10 mL of concentrated hydrochloric acid, and 260 mL of DMF. Finally, the reaction solution was poured into saturated brine, the precipitate was collected and washed with deionized water to obtain the tetramer intermediate.

[0040] A3. Synthesis of terminal amino tetramer monomer: Prepare a 30% ethanol aqueous solution, alkalize it with potassium hydroxide to control the pH value to 13, and then add the prepared tetramer intermediate to the alkaline ethanol aqueous solution at a solid-liquid mass ratio of 1:10. Heat the solution in a water bath to 50°C and stir for 8 hours to hydrolyze it. Finally, centrifuge to remove the aqueous phase and dry it to obtain the terminal amino tetramer monomer.

[0041] A4. Synthesis of the strengthening agent: Terminal amino tetramer monomer, thiodiacetic acid and DMF were added and stirred for premixing. Then EDC·HCl and HOBt were added and mixed. Nitrogen gas was introduced for protection, and the mixture was heated to 95℃ and stirred for 25 h. The raw materials for the reaction were: 0.1 mol terminal amino tetramer monomer, 0.103 mol thiodiacetic acid, 6 g EDC·HCl, 4 g HOBt, and 500 mL DMF. Finally, most of the DMF was removed by rotary evaporation under reduced pressure. After cooling, deionized water was added to precipitate the precipitate. The precipitate was dried to obtain the strengthening agent.

[0042] II. Preparation of Electromagnetic Radiation Resistant and Flame-Retardant Control Cables S1. Preparation of composite masterbatch: Take 100 parts of PVC resin, 22 parts of plasticizer, 13 parts of reinforcing agent, 8 parts of flame retardant, 4 parts of heat stabilizer, 0.9 parts of antioxidant, 2 parts of lubricant and 13 parts of filler. Add each component raw material to a high-speed mixer and mix at 600 rpm for 5 minutes. Feed the mixture into a twin-screw extruder (ceramic liner), control the temperature of the compression section to 200℃, melt-extrude the mixture, and obtain the composite masterbatch through traction, cooling and pelletizing.

[0043] S2. Metal Foil Wrapping: The wire cores are laid out and twisted together by a cabling machine. The aluminum foil is unwound by a wrapping machine, and the wrapping tension of the aluminum foil is controlled at 5N. The aluminum foil is then wrapped around the wire cores.

[0044] S3. Modified sheath extrusion: The composite masterbatch is melted and extruded through a single screw extruder (ceramic liner) with the compression section temperature controlled at 190℃. The melt is then wrapped around the surface of the wrapped metal foil through the die head. During extrusion, the pressure of the melt in the die head is controlled at 8MPa. After cooling and forming, the control cable is obtained.

[0045] Comparative Example 1 follows the same implementation process as Example 3, except that no reinforcing additives are added to the components of the sheath, and the rest is the same.

[0046] Comparative Example 2 follows the same implementation process as Example 3, but without adding reinforcing additives to the sheath components, and replacing the filler with 30 parts of conductive carbon black, with the rest remaining the same.

[0047] Take the cable prepared above, install N-type coaxial connectors at both ends, and use a vector network analyzer to measure the shielding effectiveness (SE) of the cable at 1 GHz. Bending fatigue test: The sample was mounted on a bending fatigue testing machine and repeatedly bent 1000 times at a rate of 10 times / min, with a bending radius (6 times the cable outer diameter) and a bending angle of ±90°. After bending, the shielding effectiveness was measured again. The retention rate of shielding effectiveness was calculated as follows: Retention rate = (SE after bending / SE before bending) × 100%. The specific test results are shown in Table 1. Table 1: Shielding effectiveness test results under 1GHz bending fatigue As shown in Table 1, the shielding effectiveness of the cables covered with aluminum foil all reached over 75dB. The initial shielding effectiveness was similar. After 1000 bends, the shielding effectiveness of the aluminum foil decreased significantly, indicating that the shielding structure of the aluminum foil was significantly damaged and it was difficult to form an effective shield.

[0048] Sustained Ignition Test: All the cables prepared above exhibit good flame retardancy. To simulate a sustained ignition environment for the cables in a fire or other similar conditions, the cable samples were horizontally fixed on a test frame. A tubular propane torch was used to apply a flame to the middle of the cable sample at a temperature of 750℃±50℃ for 30 minutes. Both ends of the sample remained connected to the external circuit to monitor circuit integrity. After the ignition was completed, the sample was allowed to cool naturally to room temperature. The shielding effectiveness at 1 GHz was then tested according to the above procedure. The specific test results are shown in Table 2. Table 2: Shielding effectiveness test results under 1GHz continuous ignition As shown in Table 2, under continuous ignition, the shielding effectiveness of the embodiment maintains a rate of over 90%, which is significantly better than the comparative example. This indicates that the aluminum foil layer in the cable of the embodiment maintains excellent structural stability under continuous ignition.

[0049] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A flame-retardant control cable resistant to electromagnetic radiation, comprising: The wire core and the metal foil wrapped around the outside of the wire core are characterized in that the surface of the metal foil is formed by extrusion with a modified sheath; the modified sheath is based on PVC resin and contains 10-15 phr of reinforcing additives. The strengthening agent is prepared by the following method: A1. Synthesis of passivation matrix: N-phenyl-p-phenylenediamine and anhydrous acetone were premixed and then trifluoroacetic anhydride was slowly added under an ice-water bath and a dry nitrogen atmosphere. After that, the ice-water bath was removed and the reaction continued for 1.5-2 hours. The passivation matrix was prepared after treatment. A2. Synthesis of tetramer intermediate: The passivated matrix, 4,4-diaminodiphenylamine, concentrated hydrochloric acid and DMF were premixed, cooled in an ice-water bath and then slowly added to ammonium persulfate solution. After that, the ice-water bath was removed and the process continued for 2-3 hours. The tetramer intermediate was then prepared. A3. Synthesis of terminal amino tetramer monomer: The tetramer intermediate is mixed with an alkaline ethanol aqueous solution, and the mixture is stirred and hydrolyzed in a water bath at a temperature of 40-55℃ for 6-8 hours. The resulting product is a terminal amino tetramer monomer. A4. Synthesis of strengthening agent: The terminal amino tetramer monomer, thiodiacetic acid and DMF are premixed, and then EDC·HCl and HOBt are added and mixed. Under nitrogen protection, the mixture is heated to 80-100℃ and stirred for 20-25 hours. The resulting product is a strengthening agent.

2. The electromagnetic radiation resistant flame-retardant control cable according to claim 1, characterized in that, The molar ratio of N-phenyl-p-phenylenediamine to trifluoroacetic anhydride is 1:1-1.

2.

3. The electromagnetic radiation resistant flame-retardant control cable according to claim 2, characterized in that, The molar ratio of the passivating matrix to 4,4-diaminodiphenylamine is 1:

1.

4. The electromagnetic radiation resistant flame-retardant control cable according to claim 3, characterized in that, The solid-liquid mass ratio of the tetramer intermediate to the alkaline ethanol aqueous solution is 1:8-12, and the pH of the alkaline ethanol aqueous solution is 13-14.

5. The electromagnetic radiation resistant flame-retardant control cable according to claim 4, characterized in that, The molar ratio of the terminal amino tetramer monomer to thiodiacetic acid is 1:1.03-1.

05.

6. The electromagnetic radiation resistant flame-retardant control cable according to claim 1, characterized in that, The modified sheath comprises the following components by weight: 100 parts PVC resin, 20-25 parts plasticizer, 10-15 parts reinforcing agent, 6-9 parts flame retardant, 3.5-5 parts heat stabilizer, 0.8-1.2 parts antioxidant, 2-3 parts lubricant, and 12-15 parts filler.

7. A method for preparing an electromagnetic radiation resistant flame-retardant control cable according to any one of claims 1-6, characterized in that, Specifically, the steps include the following: S1. Melt blending: Mix the components used for modifying the sheath, and granulate the mixture by melt blending extrusion using a twin-screw extruder to obtain a composite masterbatch; S2, Metal foil wrapping: The wire cores are laid out and twisted together by a cabling machine, and then metal foil is wrapped around the surface; S3. Modified sheath extrusion: The composite masterbatch is melted and extruded through a single screw extruder and coated onto the surface of the wrapped metal foil. After cooling and molding, the control cable is obtained.

8. The method for preparing an electromagnetic radiation resistant flame-retardant control cable according to claim 7, characterized in that, The wrapping tension of the metal foil is 4-6 N.

Images