A corrosion-resistant, drip-proof, fire-resistant cable and its preparation method

Abstract

This invention discloses a corrosion-resistant, drip-proof, and fire-resistant cable and its preparation method, belonging to the field of cable technology. Its features include a cable core, an insulation layer, a shielding layer, and a protective layer arranged sequentially from the inside out; the protective layer substrate is polyvinyl chloride; the outer surface of the protective layer substrate is coated with a protective coating; the protective coating comprises the following components by weight: 20-30 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend and 5-8 parts of film-forming agent. This invention, through the design of the phosphorylated chitosan sulfonyl polycarbonate functional coating, synergistically applies three mechanisms—gas-phase flame retardancy, condensed-phase carbon layer, and optimized thermal conductivity—to cable protection, specifically addressing the shortcomings of traditional cables such as "easy corrosion, high-temperature dripping, and insufficient fire resistance."

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically relating to a corrosion-resistant, drip-proof, fire-resistant cable and its preparation method. Background Technology

[0002] As an indispensable component of the power system, wires and cables play an irreplaceable role in daily life, commerce, and industry. With continuous social progress and the improvement of people's living standards, safety is increasingly valued, and while pursuing a high quality of life, the performance requirements for cables are also rising. Traditional cables are susceptible to corrosion; their insulation and sheath layers are easily eroded by chemicals, leading to performance degradation or even failure. In terms of fire resistance, ordinary cables are prone to combustion at high temperatures, and the burning process produces drippings that can cause wider fires and safety hazards.

[0003] Currently, although there are some fire-resistant cable products, they still fall short in simultaneously meeting the three properties of corrosion resistance, drip prevention, and fire resistance. In particular, the development and application of new synthetic materials need further improvement to meet the growing market demand and safety standards. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a corrosion-resistant, drip-proof, and fire-resistant cable. A protective coating of phosphorylated chitosan sulfonyl polycarbonate functional blend is introduced on the outer surface of the cable protective layer, which successfully solves the technical problem that traditional cables cannot simultaneously achieve corrosion resistance, drip resistance, and fire resistance.

[0005] The technical solution for achieving the objective of this invention is as follows:

[0006] A corrosion-resistant, drip-proof, fire-resistant cable includes a cable core, an insulation layer, a shielding layer, and a protective layer arranged sequentially from the inside out; the substrate of the protective layer is polyvinyl chloride; the outer surface of the substrate of the protective layer is coated with a protective coating; the protective coating comprises the following components by weight: 20-30 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend and 5-8 parts of film-forming agent.

[0007] The cable core is made of multiple strands of copper or aluminum wire, with a single wire diameter of 0.2~0.8 mm.

[0008] The insulating layer is one of polyvinyl chloride, polyethylene, or cross-linked polyethylene, and has a thickness of 0.5 to 1 mm.

[0009] The shielding layer is a copper wire braided mesh or an aluminum-magnesium alloy braided mesh, with a thickness of 0.18~0.36 mm.

[0010] The thickness of the protective layer substrate plus the protective coating is 2.5~5.5 mm; the thickness of the protective coating is 0.05~0.2 mm.

[0011] Preferably, the density of the polyvinyl chloride is 1.38~1.42 g / cm³. 3 The melt index is 10~15 g / 10 min (190℃ / 2.16 kg).

[0012] The film-forming agent is polyvinyl alcohol or acrylate.

[0013] The preparation method of the phosphorylated chitosan sulfonyl polycarbonate functional blend includes the following steps:

[0014] An epoxy-based silane coupling agent was dispersed in a mixed solution of N,N-dimethylformamide and water at a volume ratio of 3:7 to prepare a solution with a mass fraction of 0.5–1 wt%. The pH was adjusted to 4–5 by adding 0.1 mol / L phosphoric acid solution, and the solution was hydrolyzed at room temperature for 20–30 min to obtain a hydrolysate. The hydrolysate was mixed with phosphorylated chitosan at a molar amount of hydroxyl groups (0.1–0.3 eq), and stirred at 25–30 °C for 60–90 min to obtain a silanized solution. Then, under a nitrogen atmosphere, 1 eq of sulfonyl polycarbonate copolymer was dissolved in a mixed solution of N,N-dimethylformamide and water at a volume ratio of 3:7. The silanized solution was then slowly added to the above solution, and the mixture was stirred at 600–800 rpm until homogeneous. Next, 1 mol / L sodium bicarbonate aqueous solution was added dropwise according to the molar amount of carboxyl groups in the sulfonyl polycarbonate copolymer, and the mixture was stirred for 10–15 minutes. The mixture was stirred for min until the pH of the system stabilized at 6-7, yielding a functional blend of phosphorylated chitosan sulfonyl polycarbonate with a mass fraction of 5-10%. Then, it was subjected to vacuum distillation at 30-45℃ and 30-40 mbar under vacuum to slowly remove more than 90% of N,N-dimethylformamide. After solvent removal, the solid content of the system increased. Deionized water was slowly and evenly added dropwise to the concentrate at 1-2 mL / min under continuous stirring to ensure that the system remained homogeneous during solvent exchange without precipitation or phase separation. Finally, deionized water was added to adjust the solid content of the system to 5-10% and the viscosity to 200-300 mPa·s, forming an aqueous dispersion of the phosphorylated chitosan sulfonyl polycarbonate functional blend with water as the continuous phase.

[0015] The epoxy silane coupling agent is selected from one or two of 3-glycidyl etheroxypropyltriethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane.

[0016] The molar ratio of sodium bicarbonate to carboxyl groups of the sulfonyl polycarbonate copolymer is 1:1.

[0017] During the film-forming and drying process, the phosphoric acid groups of the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion form a dense network structure through dynamic hydrogen bonding between the phosphate groups of the phosphorylated chitosan and the carboxyl groups of the sulfonyl polycarbonate. This structure promotes the formation of an expanded char layer during combustion, thereby synergistically exerting a flame-retardant effect.

[0018] The method for preparing the phosphorylated chitosan includes the following steps:

[0019] Add 1 eq of chitosan to a three-necked flask and dissolve it in 50-60 times the amount of methanesulfonic acid relative to the chitosan. Stir until no bubbles are generated to ensure complete dissolution of chitosan. Under an argon atmosphere, control the temperature at 25-30℃ and stir continuously. Add phosphorus pentoxide to the system in 6 portions every 20-30 min, keeping the reaction temperature ≤30℃ throughout. Continue stirring for 2-3 h. After the reaction is complete, add anhydrous diethyl ether to the system to precipitate the product. Collect the solid by filtration and then wash the solid product sequentially with 5%-10% sodium bicarbonate aqueous solution, acetone, anhydrous methanol, and anhydrous diethyl ether until the filtrate is neutral and free of methanesulfonic acid residue. Then, vacuum dry at 55-65℃ for 22-28 h to obtain phosphorylated chitosan.

[0020] The total amount of phosphorus pentoxide added is equivalent to 0.12 to 0.25 times that of chitosan.

[0021] The method for preparing the sulfonyl polycarbonate copolymer includes the following steps:

[0022] Dissolve 1 eq of bisphenol monomer in 230–250 mL of 5.0 wt%–7.0 wt% sodium hydroxide aqueous solution and 110–130 mL of dichloromethane in a three-necked flask and stir at 35–45 °C. Dissolve triphosgene, triethylamine, and tetrabutylammonium bromide in dichloromethane and add this solution dropwise to the three-necked flask at a uniform rate over 25–35 min in an ice bath. After the addition is complete, raise the temperature to 40–45 °C and react for 2–3 h. After the reaction is complete, separate the organic phase and wash repeatedly with deionized water until the pH is neutral. Then precipitate the organic phase in ethanol, collect the solid product by vacuum filtration, wash with ethanol, and dry under vacuum at 75–85 °C for 40–48 h to obtain sulfonyl polycarbonate copolymer.

[0023] The bisphenol monomer is a mixture of bisphenol A: bisphenolic acid: bisphenol S in a molar ratio of (70~90): (8~20): (2~10).

[0024] The amounts of triphosgene, triethylamine, and tetrabutylammonium bromide added are 0.50 to 0.55 times, 0.10 to 0.14 times, and 0.06 to 0.07 times the amounts of bisphenol monomer, respectively.

[0025] This invention also provides a method for preparing a corrosion-resistant, drip-proof, fire-resistant cable, comprising the following steps:

[0026] (1) The materials of the insulation layer, shielding layer and protective layer are sequentially wrapped around the surface of the cable core;

[0027] (2) The cable from step (1) above is processed by a low-temperature plasma treatment device to activate the surface of the protective layer under an argon atmosphere, 50~150 W, and a line speed of 5~20 m / min.

[0028] (3) Take 20-30 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion, add 5-8 parts of film-forming agent, stir for 25-35 min until transparent, and obtain coating liquid with a viscosity of 200-300 mPa·s.

[0029] (4) Pass the activated cable through the coating liquid tank at a speed of 5~10 m / min, and then through a scraper with a gap of 0.5~2 mm. After drying, the coating thickness is 0.05~0.2 mm. Send the coated cable into the hot air drying channel with a wind speed of 1.5~2.0 m / s and cure it in two stages: the first stage: air dry at room temperature for 4~6 min; the second stage: dry at 40~50℃ for 30~40 min to obtain a corrosion-resistant, drip-proof, fire-resistant cable.

[0030] Beneficial effects

[0031] This invention, through the design of a phosphorylated chitosan sulfonyl polycarbonate functional coating, synergistically applies three mechanisms—gas-phase flame retardancy, condensed-phase carbon layer, and optimized thermal conductivity—to cable protection, specifically addressing the shortcomings of traditional cables such as "susceptibility to corrosion, high-temperature dripping, and insufficient fire resistance," and includes the following beneficial effects:

[0032] I. Flame retardant properties: Phosphorus-nitrogen-sulfonyl groups synergistically form a triple flame retardant barrier

[0033] 1. Gas phase flame retardancy: The sulfonyl groups of sulfonyl polycarbonate decompose to generate sulfurous acid, which catalyzes the polycarbonate to produce more carbon dioxide gas to dilute the combustible gas and isolate external oxygen, thereby inhibiting the continuous combustion of the matrix and suppressing the spread of flames when the cable is burning.

[0034] 2. Condensed Phase Carbon Layer: The acidic substances produced by the decomposition of sulfonyl groups promote the degradation of polycarbonate towards "carbonate bond rearrangement" and "ortho-acylphenol generation", accelerating the cross-linking of polycarbonate to form a dense carbon layer structure, thereby cutting off the heat source required for polycarbonate combustion in the condensed phase; at the same time, the phosphate groups of phosphorylated chitosan decompose into polymetaphosphoric acid at high temperature, further catalyzing the dehydration of sulfonyl polycarbonate to form a dense carbon layer, avoiding the melt collapse during the combustion of traditional polyvinyl chloride.

[0035] 3. Thermal conductivity optimization: Silanization treatment enhances the interfacial bonding between the coating and PVC, and the bonding between phosphoric acid and chitosan improves the thermal conductivity of the coating, accelerates heat dissipation, and reduces the surface temperature of the cable.

[0036] II. Corrosion Resistance: The phosphate groups of phosphorylated chitosan and the carboxyl groups of sulfonyl polycarbonate form a dynamic cross-linked network through hydrogen bonds, which can physically block the penetration of acids, alkalis and salt spray; the silanization treatment forms Si-OC bonds at the interface between the coating and polyvinyl chloride, which improves the solvent resistance; the sulfonyl groups of sulfonyl polycarbonate are chemically inert and resistant to polar solvents.

[0037] III. Anti-dripping performance: The carbon layer formed by the coating at high temperature can lock the molten polyvinyl chloride and prevent dripping; the dynamic hydrogen bonds partially dissociate at high temperature, but the local aggregated state still entangles the polyvinyl chloride molecular chains, inhibiting flow; the chitosan in the coating has an increased molecular weight after phosphorylation, forming a three-dimensional cross-linked network, which keeps the coating solid at high temperature and prevents the polyvinyl chloride from being directly exposed to the flame, thus achieving anti-dripping performance.

[0038] In addition, the low-temperature plasma treatment increases the number of polar groups on the surface of polyvinyl chloride, which is conducive to the formation of Si-OC bonds with the silanized coating, thus improving the interfacial adhesion. Moreover, this invention is based on the modification of existing polyvinyl chloride cable production lines, which makes the cost controllable and industrialization feasible. Attached Figure Description

[0039] Figure 1 This is the synthetic route for sulfonyl polycarbonate copolymers, where x is selected from any integer between 70 and 90, y is selected from any integer between 8 and 20, and z is selected from any integer between 2 and 10.

[0040] Figure 2 Fourier transform infrared spectra of chitosan and phosphorylated chitosan;

[0041] Figure 3 The Fourier transform infrared spectrum of bisphenol A, bisphenol S, bisphenolic acid, and sulfonyl polycarbonate copolymer 1 is shown. Detailed Implementation

[0042] 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.

[0043] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0044] The raw materials and equipment used in the embodiments and comparative examples are described below:

[0045] Phosphorylated chitosan: prepared in-house, the preparation method is as follows:

[0046] 1 eq of chitosan was added to a three-necked flask and dissolved in methanesulfonic acid at a ratio of 55 times that of chitosan. The mixture was stirred until no bubbles were generated, ensuring complete dissolution of the chitosan. Under an argon atmosphere, the temperature was controlled at 30°C and the mixture was stirred continuously. Phosphorus pentoxide, with a total amount equivalent to 0.25 times that of chitosan, was added to the system in 6 portions every 20 min. The reaction was continued for 2.5 h. After the reaction was completed, anhydrous diethyl ether was added to the system to precipitate the product. The solid was collected by filtration and then washed successively with 8% sodium bicarbonate aqueous solution, acetone, anhydrous methanol, and anhydrous diethyl ether until the filtrate was neutral, ensuring no methanesulfonic acid residue. The product was then dried under vacuum at 60°C for 24 h to obtain phosphorylated chitosan. The mass fraction of phosphorus was determined to be 5.0% and the degree of substitution was 0.3 by X-ray fluorescence spectrometry.

[0047] 1. Sulfonyl polycarbonate copolymer: prepared in-house, the preparation method includes the following steps:

[0048] One eq of bisphenol monomer, wherein the molar ratio of bisphenol A:bisphenolic acid:bisphenol S was 80:15:5, was dissolved in 250 mL of 5.0 wt% sodium hydroxide aqueous solution and 120 mL of dichloromethane in a three-necked flask and stirred at 35–45 °C. Triphosgene, triethylamine, and tetrabutylammonium bromide were dissolved in dichloromethane, wherein the amounts of triphosgene, triethylamine, and tetrabutylammonium bromide added were 0.55 times, 0.14 times, and 0.07 times that of the bisphenol monomer, respectively. This solution was added dropwise to the three-necked flask over 30 min in an ice bath, and the temperature was raised to 40 °C and reacted for 3 h. After the reaction was completed, the organic phase was separated and repeatedly washed with deionized water until the pH was neutral. The organic phase was then precipitated in ethanol, and the solid product was collected by vacuum filtration, washed with ethanol, and dried under vacuum at 80 °C for 48 h to obtain sulfonyl polycarbonate copolymer 1.

[0049] Sulfonyl polycarbonate copolymer 2: self-made. The preparation method is the same as that of sulfonyl polycarbonate copolymer 1, except that the molar ratio of bisphenol A: bisphenol acid: bisphenol S of the bisphenol monomer is replaced with 90:8:2, while other conditions remain unchanged, to obtain sulfonyl polycarbonate copolymer 2.

[0050] Sulfonyl polycarbonate copolymer 3: prepared in-house. The preparation method is the same as that of sulfonyl polycarbonate copolymer 1, except that the molar ratio of bisphenol A: bisphenol acid: bisphenol S of the bisphenol monomer is replaced with 70: 20: 10, while other conditions remain unchanged, to obtain sulfonyl polycarbonate copolymer 3.

[0051] Polycarbonate copolymer 4: self-made. The preparation method is the same as that of sulfonyl polycarbonate copolymer 1. The difference is that the molar ratio of bisphenol A: bisphenol acid: bisphenol S of the bisphenol monomer is replaced with 80: 20: 0, while other conditions remain unchanged, to obtain polycarbonate copolymer 4.

[0052] Sulfonyl polycarbonate copolymer 5: prepared in-house. The preparation method is the same as that of sulfonyl polycarbonate copolymer 1, except that the molar ratio of bisphenol A: bisphenol acid: bisphenol S of the bisphenol monomer is replaced with 90:0:10, while other conditions remain unchanged, to obtain sulfonyl polycarbonate copolymer 5.

[0053] Chitosan: Product No. C105799, degree of deacetylation ≥95%, viscosity 100~200 mPa·s, commercially available;

[0054] Epoxysilane coupling agent: 3-glycidyl etheroxypropyltriethoxysilane, commercially available;

[0055] Film-forming agent: 4-tert-butylcyclohexyl acrylate, commercially available;

[0056] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0057] Preparation Example

[0058] Preparation Example 1

[0059] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1: Self-made, preparation method as follows:

[0060] 0.02 eq of epoxysilane coupling agent was dispersed in a mixed solution of N,N-dimethylformamide and water in a volume ratio of 3:7 to prepare a solution with a mass fraction of 0.8 wt%. The pH was adjusted to 4.5 by adding 0.1 mol / L phosphoric acid solution, and hydrolyzed at room temperature for 25 min to obtain a hydrolysate. The hydrolysate was mixed with 0.2 eq of phosphorylated chitosan (hydroxyl molar amount) and stirred at 30 °C for 60 min to obtain a silanized solution. Then, under a nitrogen atmosphere, 1 eq of sulfonyl polycarbonate copolymer 1 was dissolved in a mixed solution of N,N-dimethylformamide and water in a volume ratio of 3:7. The silanized solution was then slowly added to the above solution, and the mixture was stirred at 600–800 rpm until the system became transparent and homogeneous. Next, 1 mol / L sodium bicarbonate aqueous solution was added dropwise according to the molar amount of carboxyl groups in the sulfonyl polycarbonate copolymer, and the mixture was stirred for 15 minutes. The mixture was stirred for min until the pH of the system stabilized at 6.5, and a functional blend of phosphorylated chitosan sulfonyl polycarbonate with a mass fraction of 8% was obtained. Then, it was slowly removed by vacuum distillation at 35°C and 40 mbar under vacuum to remove more than 90% of N,N-dimethylformamide. After solvent removal, the solid content of the system increased. Deionized water was slowly and evenly added dropwise to the concentrate at 1.5 mL / min under continuous stirring to ensure that the system remained homogeneous during solvent exchange without precipitation or phase separation. Finally, deionized water was added to adjust the solid content of the system to 5-10% and the viscosity to 250 mPa·s, forming an aqueous dispersion of phosphorylated chitosan sulfonyl polycarbonate functional blend with water as the continuous phase.

[0061] Preparation Example 2

[0062] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 2: self-made, the preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that 0.2 eq phosphorylated chitosan is replaced with 0.1 eq phosphorylated chitosan, and other conditions remain unchanged, thus obtaining phosphorylated chitosan sulfonyl polycarbonate functional blend 2.

[0063] Preparation Example 3

[0064] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 3: prepared in-house. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that 0.2 eq phosphorylated chitosan is replaced with 0.3 eq phosphorylated chitosan, while other conditions remain unchanged, thus obtaining phosphorylated chitosan sulfonyl polycarbonate functional blend 3.

[0065] Preparation Example 4

[0066] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 4: prepared in-house. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that sulfonyl polycarbonate copolymer 1 is replaced with sulfonyl polycarbonate copolymer 2, while other conditions remain unchanged, thus obtaining phosphorylated chitosan sulfonyl polycarbonate functional blend 4.

[0067] Preparation Example 5

[0068] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 5: prepared in-house. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that sulfonyl polycarbonate copolymer 1 is replaced with sulfonyl polycarbonate copolymer 3, while other conditions remain unchanged, thus obtaining phosphorylated chitosan sulfonyl polycarbonate functional blend 5.

[0069] Preparation Example 6

[0070] Phosphorylated chitosan polycarbonate functional blend aqueous dispersion 6: self-made. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that sulfonyl polycarbonate copolymer 1 is replaced with polycarbonate copolymer 4, and other conditions remain unchanged, thus obtaining phosphorylated chitosan polycarbonate functional blend 6.

[0071] Preparation Example 7

[0072] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 7: prepared in-house. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that sulfonyl polycarbonate copolymer 1 is replaced with sulfonyl polycarbonate copolymer 5, while other conditions remain unchanged, thus obtaining phosphorylated chitosan sulfonyl polycarbonate functional blend 7.

[0073] Preparation Example 8

[0074] Phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 8: prepared in-house. The preparation method is the same as that of phosphorylated chitosan sulfonyl polycarbonate functional blend 1, except that no epoxy silane coupling agent is added, while other conditions remain unchanged, to obtain phosphorylated chitosan sulfonyl polycarbonate functional blend 8.

[0075] Example

[0076] Example 1

[0077] Corrosion-resistant, drip-proof, fire-resistant cable 1: Self-made, preparation method as follows:

[0078] (1) The materials of the insulation layer, shielding layer and protective layer are sequentially wrapped around the surface of the cable core;

[0079] (2) The cable from step (1) above is processed by a low-temperature plasma treatment device to activate the surface of the protective layer under the conditions of argon atmosphere, 100 W and linear speed of 100 m / min;

[0080] (3) Take 25 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1, add 7 parts of film-forming agent, stir for 30 min until transparent, and obtain coating liquid with a viscosity of 250 mPa·s.

[0081] (4) The activated cable is passed through the coating liquid tank at a speed of 10 m / min, and then through a scraper with a gap of 1 mm. After drying, the coating thickness is 0.1 mm. The coated cable is sent into the hot air drying channel and cured in two stages: the first stage: air drying at room temperature for 5 min; the second stage: drying at 50℃ for 40 min, to obtain corrosion-resistant, drip-proof, fire-resistant cable 1.

[0082] Example 2

[0083] Corrosion-resistant, drip-proof, and fire-resistant cable 2: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the number of parts of phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with 20 parts, and the number of parts of film-forming agent is replaced with 5 parts. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 2.

[0084] Example 3

[0085] Corrosion-resistant, drip-proof, and fire-resistant cable 3: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the number of parts of phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with 30 parts, and the number of parts of film-forming agent is replaced with 8 parts. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 3.

[0086] Example 4

[0087] Corrosion-resistant and drip-proof fire-resistant cable 4: self-made. The preparation method is the same as that of corrosion-resistant and drip-proof fire-resistant cable 1. The difference is that the scraper gap in step (4) is replaced with 2 mm, and other conditions remain unchanged. Corrosion-resistant and drip-proof fire-resistant cable 4 is obtained.

[0088] Example 5

[0089] Corrosion-resistant, drip-proof, and fire-resistant cable 5: Self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 2. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 5.

[0090] Example 6

[0091] Corrosion-resistant, drip-proof, and fire-resistant cable 6: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 3. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 6.

[0092] Example 7

[0093] Corrosion-resistant, drip-proof, and fire-resistant cable 7: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 4. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 7.

[0094] Example 8

[0095] Corrosion-resistant, drip-proof, and fire-resistant cable 8: Self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 5. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 8.

[0096] Comparative Example 1

[0097] Corrosion-resistant, drip-proof, and fire-resistant cable 9: Self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, and fire-resistant cable 1. The difference is that the phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan polycarbonate functional blend aqueous dispersion 6. All other conditions remain unchanged to obtain corrosion-resistant, drip-proof, and fire-resistant cable 9.

[0098] Comparative Example 2

[0099] Corrosion-resistant, drip-proof, fire-resistant cable 10: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, fire-resistant cable 1, except that phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 7, while other conditions remain unchanged, thus obtaining corrosion-resistant, drip-proof, fire-resistant cable 10.

[0100] Comparative Example 3

[0101] Corrosion-resistant, drip-proof, fire-resistant cable 11: self-made. The preparation method is the same as that of corrosion-resistant, drip-proof, fire-resistant cable 1, except that phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 1 is replaced with phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion 8, while other conditions remain unchanged, thus obtaining corrosion-resistant, drip-proof, fire-resistant cable 11.

[0102] The following are the test methods for performance parameters involved in this invention:

[0103] 1. Fourier Transform Infrared Spectroscopy (FT-IR): FT-IR analysis was performed using a Thermo Nicolet IS10 Fourier Transform Infrared Spectrometer; in the Fourier Transform Infrared spectrum of phosphorylated chitosan, ammonium ions were clearly observed at 1630 cm⁻¹. -1 The asymmetric deformation vibration peak at 1528 cm⁻¹ -1 The symmetrical deformation vibration peak at 1215 cm⁻¹ strongly indicates that some amino groups have undergone protonation. -1 A vibrational peak of phosphorus-oxygen double bond was detected at 2700–3600 cm⁻¹, confirming the successful introduction of the phosphate group; no SC bond was found, indicating the absence of methanesulfonic acid residue in the system. Furthermore, vibrational peaks were observed at 2700–3600 cm⁻¹. -1 Within the wavenumber range, there is a difference in the absorption intensity distribution between phosphorylated chitosan and chitosan: this difference is caused by the phosphate groups and ammonium ions introduced during the phosphorylation process. These groups enable the hydroxyl groups to form various types of hydrogen bonds with the amino groups, resulting in strong absorption in the wavenumber range from hydroxyl groups to C-H bonds.

[0104] 2. Fire resistance test of cables: The test shall be conducted in accordance with GB / T 19216 "Line integrity test of cables or optical cables under flame conditions", with a fire supply time of 60 minutes. The test is considered passed if the fuse of the test device does not break and the indicator light does not go out.

[0105] 3. Oxygen Index Test: The oxygen index is an important flame retardant indicator for non-metallic materials used in flame-retardant cables. It refers to the oxygen concentration required for a material sample to maintain stable combustion in a mixed flow of oxygen and nitrogen under specified conditions, expressed as the volume percentage of oxygen in the mixed flow. An oxygen index of 22 or below indicates a flammable material, an oxygen index of 22 to 27 indicates a flame-retardant material, and an oxygen index above 27 indicates a highly flame-retardant material.

[0106] 4. Light transmittance test: Since burning cables produce smoke, which affects people's vision and reduces the chance of escape, it is necessary to test the amount of smoke generated after the cables burn. According to the test standard GB / T 17651-2021, five samples are selected for each embodiment and bundled together. The samples are placed on a combustion pan and burned. The light transmittance is measured in a room with a fixed volume. If the light transmittance is less than 60%, the test is unqualified.

[0107] 5. Drip test: Test the dripping situation of burning within 1200 s according to GB / T 31248-2014.

[0108] 6. Corrosion test: The corrosion level shall be tested according to the test method of GB / T 17650.2-2021, where a1 level is conductivity ≤2.5 μS / mm and pH≥4.3, a2 level is conductivity ≤10 μS / mm and pH≥4.3, and a3 level is not a grade of a2.

[0109] Table 1 Comparison of the performance of protective layer materials

[0110]

[0111] As shown in Table 1, all examples 1-8 passed the fire resistance test. It is speculated that the functional blends synergistically form a strong char layer under flame. The phosphoric acid groups of phosphorylated chitosan catalyze the dehydration of polyvinyl chloride and sulfonyl polycarbonate to form char. At the same time, the sulfonyl groups decompose to release sulfur dioxide, dilute oxygen, and quench free radicals. The formation of this char layer can effectively isolate flame and heat, and protect the integrity of the cable core structure of the internal insulation layer. All examples 1-3 failed the fire resistance test. It is speculated that Example 1 used a blend without sulfonyl groups, which lacks a gas-phase flame retardant mechanism. The char formation effect of phosphorylated chitosan alone cannot completely resist high-temperature flames, resulting in an insufficiently dense char layer or burn-through. Example 2 used a blend without bisphenol A, which has a weak hydrogen bond cross-linking network, resulting in reduced coating cohesion and char quality, leading to premature char layer cracking. Example 3 did not use a silane coupling agent, resulting in poor interfacial bonding between the coating and the polyvinyl chloride body. When exposed to fire, the coating is easy to peel off from the polyvinyl chloride surface and blister, losing its protective function.

[0112] Regarding the oxygen index, in Examples 1-3, as the amount of functional additives increased from 20 parts to 30 parts, the effective components of phosphoric chitosan and sulfonyl polycarbonate increased, and the concentrations of phosphorus, sulfur, and nitrogen flame retardant elements increased, resulting in enhanced synergistic flame retardant effects. Compared with Examples 5 and 6, when the amount of phosphoric chitosan added increased, the phosphorus content and char-forming catalysis improved, and the oxygen isolation effect was better, thus increasing the oxygen index. Comparative Example 1 lacked sulfonyl groups, which prevented the efficient synergy between the gas phase and the condensed phase, resulting in a decrease in flame retardant efficiency.

[0113] Regarding light transmittance, the transmittance of Examples 1-8 was 68% or higher, presumably because the sulfonyl decomposition catalyzed the formation of the char layer, inhibiting the combustion and smoke generation of the internal materials. Example 6 had the highest phosphorylated chitosan content, thus exhibiting the strongest char-forming catalytic effect, the least complete combustion, and the fewest smoke particles, resulting in the highest light transmittance. Although Comparative Example 3 had some flame retardancy, its poor coating adhesion could lead to localized peeling when exposed to fire, resulting in incomplete combustion of the polyvinyl chloride matrix and the generation of more smoke, thus its light transmittance was lower than that of the Examples.

[0114] Regarding dripping, none of the embodiments dripped. It is speculated that this is because the char layer physically encapsulates the molten PVC, and the high molecular weight cross-linked network of phosphorylated chitosan helps to lock the molecular chains. In addition, although the hydrogen bond network partially dissociates at high temperatures, it can still inhibit flow. The synergy of these three factors makes the cable drip-free. Comparative Example 1 lacks sulfonyl groups, which cannot work efficiently with phosphorylated chitosan, resulting in insufficient char layer strength, which cannot encapsulate the molten PVC and causes severe dripping. Comparative Example 2 lacks bisphenol A, resulting in insufficient coating cohesion. It is easily broken by the molten PVC at high temperatures, resulting in a small amount of dripping. Comparative Example 3 has poor interfacial bonding between the coating and the substrate. After being exposed to fire, the coating curls and falls off as a whole, losing its anti-drip function.

[0115] Regarding the corrosion rating, all of Examples 1 to 8 were rated a1, presumably because the coating formed a dense physical barrier through hydrogen bonds and silane coupling agents, which effectively blocked the penetration of corrosive media. In Comparative Example 2, the hydrogen bond network was weak, the coating density decreased, and corrosive media could penetrate more easily. In Comparative Example 3, due to the poor interface between the coating and the substrate, corrosive media could easily penetrate, resulting in a decrease in the corrosion rating.

[0116] In summary, this invention utilizes phosphorylated chitosan as the catalyst for char formation, which is the core of the condensed-phase flame retardancy and anti-dripping effect; sulfonyl polycarbonate provides gas-phase flame retardancy and enhances char formation, and works synergistically with phosphorylated chitosan through hydrogen bonds; the silane coupling agent acts as an interfacial bridge, ensuring strong coating adhesion and is crucial for long-term stable performance. The absence of any one of these components will lead to the failure of the entire synergistic system and a sharp decline in performance. Example 1 achieves the best balance in terms of performance and economy, and is the optimal implementation scheme.

[0117] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A corrosion-resistant, drip-proof, fire-resistant cable, characterized in that, The cable comprises, from the inside out, a cable core, an insulation layer, a shielding layer, and a protective layer; the protective layer substrate is polyvinyl chloride; the outer surface of the protective layer substrate is coated with a protective coating; the protective coating comprises, by weight, the following components: 20-30 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend, and 5-8 parts of film-forming agent; the thickness of the protective coating is 0.05-0.2 mm. mm; the phosphorylated chitosan sulfonyl polycarbonate functional blend is composed of an epoxy silane coupling agent, phosphorylated chitosan, and a sulfonyl polycarbonate copolymer; the preparation method of the phosphorylated chitosan sulfonyl polycarbonate functional blend includes the following steps: dissolving the epoxy silane coupling agent in the mixed solution, adjusting the pH to 4-5 to obtain a hydrolysate; mixing the hydrolysate with phosphorylated chitosan to obtain a silanized solution; dissolving the sulfonyl polycarbonate copolymer in the mixed solution, then slowly adding the silanized solution, stirring, adjusting the pH to 6-7 to obtain the phosphorylated chitosan sulfonyl polycarbonate functional blend, removing N,N-dimethylformamide, adding deionized water to exchange the solvent, and obtaining an aqueous dispersion of the phosphorylated chitosan sulfonyl polycarbonate functional blend with water as the continuous phase.

2. The corrosion-resistant, drip-proof, fire-resistant cable as described in claim 1, characterized in that, The cable core is made of multi-strand copper or aluminum wire with a single wire diameter of 0.2-0.8 mm; the insulation layer is made of one of polyvinyl chloride, polyethylene, or cross-linked polyethylene with a thickness of 0.5-1 mm; the shielding layer is made of copper wire braided mesh or aluminum-magnesium alloy braided mesh with a thickness of 0.18-0.36 mm; the degree of deacetylation of the chitosan raw material used in the phosphorylated chitosan is ≥95%, and the viscosity is 100-200 mPa·s.

3. The corrosion-resistant, drip-proof, fire-resistant cable as described in claim 1, characterized in that, The mixed solution is a mixture of N,N-dimethylformamide and water in a volume ratio of 3:7; the mass fraction of the epoxy silane coupling agent mixed solution is 0.5~1.0 wt%; the molar ratio of the phosphorylated chitosan and sulfonyl polycarbonate copolymer is (0.1~0.3):1; the water dispersion of the phosphorylated chitosan sulfonyl polycarbonate functional blend with water as the continuous phase has a solid content of 5~10% and a viscosity of 200~300 mPa·s.

4. The corrosion-resistant, drip-proof, fire-resistant cable as described in claim 1, characterized in that, The method for preparing the phosphorylated chitosan includes the following steps: Chitosan and methanesulfonic acid were mixed at a molar ratio of 1:(50~60) and stirred until no bubbles were generated, ensuring that the chitosan was completely dissolved. Under an argon atmosphere, the temperature was controlled at 25~30℃ and stirring was continued. Phosphorus pentoxide was added to the system in 6 portions every 20~30 min, with a total amount equivalent to 0.12~0.25 times that of chitosan. After the reaction was completed, anhydrous diethyl ether was added to the system to precipitate the product. The product was then purified to obtain phosphorylated chitosan.

5. The corrosion-resistant, drip-proof, fire-resistant cable as described in claim 1, characterized in that, The method for preparing the sulfonyl polycarbonate copolymer includes the following steps: Bisphenol monomer was dissolved in sodium hydroxide aqueous solution and dichloromethane in a three-necked flask and stirred. Triphosgene, triethylamine and tetrabutylammonium bromide were dissolved in dichloromethane and added dropwise to the above system at a uniform rate. The reaction was maintained at 40-45℃. After the reaction was completed, the product was purified to obtain sulfonyl polycarbonate copolymer.

6. The corrosion-resistant, drip-proof, fire-resistant cable as described in claim 5, characterized in that, The bisphenol monomer is a mixture of bisphenol A: bisphenolic acid: bisphenol S in a molar ratio of (70~90): (8~20): (2~10); the sodium hydroxide aqueous solution has a mass fraction of 5.0 wt%~7.0 wt%.

7. The method for preparing the corrosion-resistant, drip-proof, fire-resistant cable as described in any one of claims 1 to 6, comprising the following steps: (1) The materials of the insulation layer, shielding layer and protective layer are sequentially wrapped around the surface of the cable core; (2) The cable from step (1) above is processed by a low-temperature plasma treatment device to activate the surface of the protective layer under an argon atmosphere, 50~150 W, and a line speed of 5~20 m / min. (3) Take 20-30 parts of phosphorylated chitosan sulfonyl polycarbonate functional blend aqueous dispersion, add 5-8 parts of film-forming agent to prepare 0.5 wt% film-forming agent solution, stir for 25-35 min until transparent, and obtain coating liquid with viscosity of 200-300 mPa·s; (4) Pass the activated cable through the coating liquid tank at a speed of 5~10 m / min, and then through a scraper with a gap of 0.5~2 mm. After drying, the coating thickness is 0.05~0.2 mm. Send the coated cable into the hot air drying channel and cure it in two stages: the first stage: air dry at room temperature for 4~6 min. Second stage: Dry at 40~50℃ for 30~40 minutes to obtain corrosion-resistant, drip-proof, and fire-resistant cable.

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