Waterproof copper sheath flexible fireproof cable

Abstract

The invention discloses a waterproof copper sheath flexible fireproof cable, and relates to the technical field of cables, the waterproof copper sheath flexible fireproof cable comprises a cable inner core, an isolation layer, a copper sheath and an outer sheath, the isolation layer, the copper sheath and the outer sheath sequentially wrap the cable inner core from inside to outside, and the outer sheath is made of a polyethylene composite material; the polyethylene composite material is prepared from the following raw materials in parts by weight: 100 parts of polyethylene resin, 8-15 parts of modified ammonium polyphosphate, 5-10 parts of aluminum hydroxide, 2-5 parts of a compatilizer, 0.1-0.5 part of an antioxidant and 0.5-1 part of a lubricant. The flame retardant property of the cable is remarkably improved through a phosphorus-aluminum synergistic flame retardant system, the mechanical property and flexibility of the cable are enhanced through an interface optimization mode, and the cable has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically relating to a water-blocking copper-sheathed flexible fireproof cable. Background Technology

[0002] In the development of industries such as power and communications, cables, as the core carriers of energy and information, are crucial to the normal order of social production and life. Especially in scenarios with extremely high safety requirements, such as buildings, rail transit networks, and petrochemical industrial parks, the flame-retardant performance of cables becomes a key line of defense in preventing the spread of fire and ensuring emergency power supply and uninterrupted communication in the event of a fire. However, currently widely used cable products still have significant technical shortcomings in flame-retardant performance, making it difficult to withstand the harsh tests of complex fire conditions.

[0003] Traditionally, the selection of flame-retardant materials for cables has relied heavily on the large-scale application of a single flame retardant to achieve fire protection. In this approach, the flame retardant's mechanism of action is relatively simple: it either slows combustion initially by absorbing heat and lowering the temperature, or it merely forms an insulating layer to hinder oxygen contact. This makes it difficult to create a multi-dimensional, continuous flame-retardant protection system, resulting in a significant reduction in overall flame-retardant efficiency. When subjected to sustained high-temperature flames, a single flame retardant often exhausts its flame-retardant efficacy in a short time, failing to build a stable and durable fire barrier. This allows critical structures such as the cable insulation and sheath to be rapidly destroyed by the flames, not only contributing to the spread of fire but also potentially causing secondary risks such as short circuits and signal interruptions. Therefore, it is necessary to provide a water-resistant, flame-retardant, copper-sheathed flexible fire-resistant cable. Summary of the Invention

[0004] The purpose of this invention is to provide a water-blocking copper-sheathed flexible fireproof cable to solve the problem of poor flame retardancy in existing cables.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A water-blocking copper-sheathed flexible fireproof cable includes a cable core, and an isolation layer, a copper sheath, and an outer sheath sequentially covering the cable core from the inside out. The cable core is formed by twisting multiple inner core units. Each inner core unit includes two twisted insulated core wires and a shielding layer covering the two insulated core wires. The shielding layer is braided from first copper wires with a braiding density greater than 80%. The insulated core wires include a conductor and an insulation layer covering the conductor. The conductor is formed by twisting multiple second copper wires with a single wire diameter of less than 0.18 mm. The outer sheath is made of polyethylene composite material.

[0007] Furthermore, the polyethylene composite material is prepared by the following steps:

[0008] Prepare the following raw materials in parts by weight: 100 parts polyethylene resin, 15-25 parts compound flame retardant, 2-5 parts compatibilizer, 0.1-0.5 parts antioxidant, and 0.5-1 parts lubricant; mix the above raw materials, then extrude and granulate to obtain a polyethylene composite material, wherein the extrusion temperature is 150-180℃.

[0009] Furthermore, the compound flame retardant is composed of modified ammonium polyphosphate and aluminum hydroxide mixed in a mass ratio of 1:(0.5-2).

[0010] Furthermore, the modified ammonium polyphosphate is prepared through the following steps:

[0011] A sulfur-containing aminosilane coupling agent was mixed with anhydrous ethanol and stirred at 50°C for 30 min to obtain a sulfur-containing aminosilane coupling agent mixture. Ammonium polyphosphate was mixed with anhydrous ethanol and stirred at 60°C for 1 h to obtain an ammonium polyphosphate mixture. The sulfur-containing aminosilane coupling agent mixture was added to the ammonium polyphosphate mixture and stirred at 60°C for 1 h. The mixture was then filtered to obtain a solid product. The solid product was dried at 60°C for 3 h to obtain modified ammonium polyphosphate.

[0012] In the above reaction, the main process is the condensation reaction between the phosphorus-containing segments of ammonium polyphosphate and the amino groups in the sulfur-containing aminosilane coupling agent. The core is the nucleophilic substitution-elimination process: since the -NH2 in the silane contains lone pair electrons, it can act as a nucleophile to attack the P atoms in the phosphorus-containing segments that are electron-deficient due to the electron cloud shift caused by the P=O double bond, the old bond NH4-O is broken and a new -NH2-bridge bond is formed. At the same time, the release of NH3 gas from the system pushes the equilibrium to the right. After multiple rounds of reaction, a polymer containing -NH2-bridge bonds and siloxane alkyl groups is constructed, achieving molecular chain growth.

[0013] Furthermore, the ratio of sulfur-containing aminosilane coupling agent to anhydrous ethanol in the sulfur-containing aminosilane coupling agent mixture is (1-3) g: 5 mL.

[0014] Furthermore, the ratio of ammonium polyphosphate to anhydrous ethanol in the ammonium polyphosphate mixture is (6-10) g: 30 mL.

[0015] Furthermore, the sulfur-containing aminosilane coupling agent is prepared by the following steps:

[0016] γ-chloropropyltriethoxysilane, cystamine, potassium carbonate, potassium iodide, and anhydrous toluene were added to a dry reaction vessel. The vessel was subjected to nitrogen purging three times under ice bath conditions. The reaction was carried out at 80°C for 24 hours under N2 protection. After the reaction was completed, the inorganic salts were removed by suction filtration, the toluene was removed by rotary evaporation, and the vessel was dried under vacuum for 24 hours to obtain a sulfur-containing aminosilane coupling agent.

[0017] Furthermore, the ratio of the amounts of γ-chloropropyltriethoxysilane, cystamine, potassium carbonate, potassium iodide and anhydrous toluene is 0.5 mol: 0.6 mol: (1.4-1.6) mol: (0.04-0.06) mol: (500-700) mL.

[0018] The preparation method of this water-blocking copper-sheathed flexible fire-resistant cable includes the following steps:

[0019] S1. The second copper wire is stranded into a conductor, and an insulating layer made of LDPE material is wrapped around the conductor using an extrusion die to obtain an insulated core wire;

[0020] S2. Twist two insulated core wires together and wrap a shielding layer around the two insulated core wires to obtain the inner core unit;

[0021] S3. Multiple inner core units are twisted together in a concentric twisting manner to obtain the cable inner core. An isolation layer is evenly wrapped around the cable inner core. A copper sheath is wrapped around the surface of the isolation layer. Then, a sheath made of polyethylene composite material is evenly wrapped around the copper sheath by extrusion to obtain a water-blocking copper sheath flexible fireproof cable.

[0022] Furthermore, the thickness of the copper sheath is 0.08-0.1 mm.

[0023] Furthermore, the thickness of the shielding layer is 0.05-0.08 mm.

[0024] Furthermore, the insulating layer is formed by foaming and extruding LDPE material, with a thickness of 0.3-0.8 mm.

[0025] Furthermore, the insulating layer is made of polyester tape wrapped around it, with a thickness of 0.03-0.08 mm.

[0026] Furthermore, the compatibilizer maleic anhydride is grafted onto linear low-density polyethylene at a grafting rate of 0.7-1.0%.

[0027] Furthermore, the antioxidant is antioxidant 1010 or antioxidant 2246.

[0028] Furthermore, the lubricant is one or more of zinc stearate, barium stearate, calcium stearate, and chlorinated paraffin.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention utilizes a sulfur-containing aminosilane coupling agent to modify ammonium polyphosphate. The modified ammonium polyphosphate is then compounded with aluminum hydroxide in a specific mass ratio to construct a highly efficient intumescent flame-retardant system. On one hand, during combustion, the modified ammonium polyphosphate releases polyphosphoric acid, which catalyzes the dehydration of polyethylene into char. The sulfur element simultaneously promotes the formation of a dense carbon-silicon layer, effectively isolating oxygen and heat. On the other hand, combined with the heat absorption and cooling effect and physical barrier effect of aluminum hydroxide, a stepped flame-retardant system is formed, significantly improving the fire resistance limit of the cable. This effectively delays or prevents the spread of flames, and the halogen-free flame-retardant system completely avoids the generation of toxic hydrogen halides, meeting the requirements of high-safety scenarios.

[0031] 2. This invention utilizes a sulfur-containing aminosilane coupling agent to modify ammonium polyphosphate. The modified ammonium polyphosphate has significantly improved compatibility with polyethylene due to the introduction of organic groups on its surface, resulting in more uniform dispersion in the composite material. This significantly improves the mechanical properties of the outer sheath material and avoids the brittleness problem caused by the addition of a large amount of inorganic flame retardant in traditional flame-retardant cables, ensuring that the material is not prone to cracking during long-term use. In addition, the flexible long chains introduced into the modified ammonium polyphosphate can increase the mobility of the molecular chains, further enhancing the flexibility of the cable.

[0032] 3. This invention utilizes modified ammonium polyphosphate and aluminum hydroxide to prepare a polyethylene composite outer sheath. Since the modified ammonium polyphosphate contains hydrophobic siloxane groups, a water-repellent layer with a "lotus effect" can be formed on the surface of the sheath. This water-repellent layer can form a multi-layer water-blocking system of "outer sheath-copper sheath-isolation layer" with the copper sheath and the isolation layer, which greatly improves the water-blocking performance of the cable. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. The polyethylene resin used in the following examples was purchased from Panjin Petrochemical, model HD5010. All other materials and reagents used, unless otherwise specified, are commercially available.

[0035] Preparation Example 1

[0036] A sulfur-containing aminosilane coupling agent is prepared by the following steps:

[0037] 120.0 g of γ-chloropropyltriethoxysilane, 91.2 g of cystamine, 207.0 g of potassium carbonate, 8.3 g of potassium iodide, and 600 mL of anhydrous toluene were added to a dry reaction vessel. The vessel was purged with nitrogen three times under ice bath conditions and reacted at 80 °C for 24 h under N2 protection. After the reaction was completed, inorganic salts were removed by vacuum filtration, toluene was removed by rotary evaporation, and the vessel was dried under vacuum for 24 h to obtain a sulfur-containing aminosilane coupling agent.

[0038] Preparation Example 2

[0039] A modified ammonium polyphosphate is prepared by the following steps:

[0040] 20g of the sulfur-containing aminosilane coupling agent obtained in Preparation Example 1 was mixed with 100mL of anhydrous ethanol and stirred at 50°C for 30min to obtain a sulfur-containing aminosilane coupling agent mixture. 80g of ammonium polyphosphate was mixed with 300mL of anhydrous ethanol and stirred at 60°C for 1h to obtain an ammonium polyphosphate mixture. The sulfur-containing aminosilane coupling agent mixture was added to the ammonium polyphosphate mixture and stirred at 60°C for 1h. The mixture was filtered to obtain a solid product, which was then dried at 60°C for 3h to obtain modified ammonium polyphosphate.

[0041] Preparation Example 3

[0042] A compound flame retardant is prepared by mixing 1 kg of modified ammonium polyphosphate obtained in Preparation Example 2 and 0.5 kg of aluminum hydroxide.

[0043] Preparation Example 4

[0044] A compound flame retardant is prepared by mixing 1 kg of modified ammonium polyphosphate obtained in Preparation Example 2 and 1 kg of aluminum hydroxide.

[0045] Preparation Example 5

[0046] A compound flame retardant is prepared by mixing 0.5 kg of modified ammonium polyphosphate obtained in Preparation Example 2 and 1 kg of aluminum hydroxide.

[0047] Comparative Preparation Example 1

[0048] A compound flame retardant is composed of 1 kg of ammonium polyphosphate and 0.5 kg of aluminum hydroxide.

[0049] Example 1

[0050] A polyethylene composite material is prepared by the following steps:

[0051] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 20 parts of the compound flame retardant obtained in Preparation Example 3, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed and then extruded and granulated by a twin-screw extruder to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0052] Example 2

[0053] A polyethylene composite material is prepared by the following steps:

[0054] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 20 parts of the compound flame retardant obtained in Preparation Example 4, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0055] Example 3

[0056] A polyethylene composite material is prepared by the following steps:

[0057] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 20 parts of the compound flame retardant obtained in Preparation Example 5, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0058] Example 4

[0059] A polyethylene composite material is prepared by the following steps:

[0060] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 15 parts of the compound flame retardant obtained in Preparation Example 3, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0061] Example 5

[0062] A polyethylene composite material is prepared by the following steps:

[0063] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 25 parts of the compound flame retardant obtained in Preparation Example 3, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0064] Comparative Example 1

[0065] A polyethylene composite material is prepared by the following steps:

[0066] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 20 parts of modified ammonium polyphosphate obtained in Preparation Example 2, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0067] Comparative Example 2

[0068] A polyethylene composite material is prepared by the following steps:

[0069] Based on 1 kg of polyethylene resin, the following raw materials were weighed according to the following weight ratio: 100 parts of polyethylene resin, 20 parts of aluminum hydroxide, 2 parts of maleic anhydride-grafted linear low-density polyethylene (grafting rate of 0.7%), 0.3 parts of antioxidant 1010, and 0.7 parts of zinc stearate. The above raw materials were mixed, extruded, and granulated to obtain a polyethylene composite material, wherein the extrusion temperature was 150-180℃.

[0070] Comparative Example 3

[0071] A polyethylene composite material was prepared according to the method of Example 1, except that "20 parts of the compound flame retardant obtained in Preparation Example 3" in Example 1 was replaced with "10 parts of the compound flame retardant obtained in Preparation Example 3".

[0072] Comparative Example 4

[0073] A polyethylene composite material was prepared according to the method of Example 1, except that "20 parts of the compound flame retardant obtained in Preparation Example 3" in Example 1 was replaced with "30 parts of the compound flame retardant obtained in Preparation Example 3".

[0074] Comparative Example 5

[0075] A polyethylene composite material was prepared according to the method of Example 1, except that the "compound flame retardant obtained in Preparation Example 3" in Example 1 was replaced with an equal part by weight of "compound flame retardant obtained in Comparative Preparation Example 1".

[0076] A water-blocking copper-sheathed flexible fireproof cable includes a cable core, and an isolation layer, a copper sheath, and an outer sheath sequentially covering the cable core from the inside out. The cable core is composed of three inner core units twisted together. Each inner core unit includes two twisted insulated core wires and a shielding layer covering the two insulated core wires. The shielding layer is braided from a first copper wire with a braiding density greater than 80%. The insulated core wires include a conductor and an insulation layer covering the conductor. The conductor is composed of four second copper wires with a single wire diameter of 0.15 mm twisted together. The outer sheath is made of polyethylene composite material.

[0077] This water-blocking copper-sheathed flexible fire-resistant cable is manufactured through the following steps:

[0078] S1. The second copper wire is stranded into a conductor, and an insulating layer made of LDPE material is wrapped around the conductor using an extrusion die to obtain an insulated core wire;

[0079] S2. Twist two insulated core wires together and wrap a shielding layer around the two insulated core wires to obtain the inner core unit;

[0080] S3. Three inner core units are twisted together in a concentric manner to obtain the cable inner core. An isolation layer is evenly wrapped around the cable inner core. A copper sheath is wrapped around the surface of the isolation layer. Then, a sheath made of polyethylene composite material is evenly wrapped around the copper sheath by extrusion to obtain a water-blocking copper sheath flexible fireproof cable.

[0081] The copper sheath is 0.1 mm thick, the shielding layer is 0.05 mm thick, the insulation layer is formed by foaming and extruding LDPE material and is 0.3 mm thick, and the isolation layer is made of polyester tape wrapped around it and is 0.03 mm thick.

[0082] Water-blocking copper-sheathed flexible fire-resistant cables were manufactured using the polyethylene composite materials obtained in Examples 1-5 and Comparative Examples 1-5 as the outer sheath. The tensile strength and elongation at break of the outer sheath were tested using a CTM2050 universal testing machine according to ASTM / D638 standards at a tensile speed of 50 mm / min. The flame-retardant performance of the cables was evaluated according to the international standard IEC60332, including a vertical burning test. According to flame-retardant rating A (IEC603323-21): the cable did not exhibit sustained vertical burning within 60 minutes; and according to rating B (IEC603323-22): within a 40-minute test period, the cable bundle propagation distance should not exceed 3.5 meters, and no burning residue should fall. Class C (IEC603323-23): The cable can burn within 20 minutes, but the vertical propagation distance must not exceed 2.5 meters, and it is qualified if no residue falls off; Class D (IEC603323-24): The cable can be ignited alone and does not continue to burn, with no limit on vertical propagation distance or time; Refer to the requirements of GB / T7424.2-2008 "General Specification for Optical Cables Part 2 Basic Test Methods for Optical Cables" to conduct a water seepage test on the cable. Take a 20m length of cable, make a sample according to the standard requirements, and after the sample is bent in a U-shape, take a 3m length of sample from the center of the sample, apply a water-tight sleeve to one end of the sample, apply 1m of water at (20±5)℃ for 24h, and observe the water leakage.

[0083] The test results are shown in Table 1:

[0084] Table 1

[0085]

[0086]

[0087] As shown in Table 1, the water-blocking copper-sheathed flexible fire-resistant cable prepared by this invention exhibits excellent comprehensive performance: in terms of mechanical properties, the tensile strength exceeds 13.9 MPa, and the elongation at break is higher than 351%; in terms of flame retardant performance, the flame retardant rating of Examples 1-5 is all A; in terms of water-blocking performance, the longitudinal water-blocking test of Examples 1-5 shows no leakage. In contrast, combining Examples 1 and Comparative Example 1, due to the lack of aluminum hydroxide, a phosphorus-aluminum synergistic flame-retardant system cannot be formed, resulting in a significant decrease in the flame-retardant performance of the cable; combining Examples 1 and Comparative Example 2, due to the lack of modified ammonium polyphosphate, neither the interfacial compatibility between the inorganic filler and the polyethylene matrix can be improved, nor can a phosphorus-aluminum synergistic flame-retardant system be formed. The aluminum-co-fueled flame-retardant system and the multi-layered water-blocking system led to a deterioration in the mechanical properties, flame-retardant properties, and water-blocking properties of the cable. In Example 1 and Comparative Example 3, the lower addition amount of the compounded flame retardant than the preferred ratio resulted in reduced flame-retardant and water-blocking efficiencies, leading to a decrease in the cable's mechanical properties, flame-retardant properties, and water-blocking properties. In Example 1 and Comparative Example 4, the excessive addition of the compounded flame retardant caused the inorganic filler to agglomerate, resulting in poor dispersion in the matrix and a decrease in the cable's mechanical properties and water-blocking properties. In Example 1 and Comparative Example 5, the lack of modification of the ammonium polyphosphate prevented the improvement of the interfacial compatibility between the inorganic filler and the polyethylene matrix, and also prevented the formation of a multi-layered water-blocking system, resulting in a decrease in the cable's mechanical properties and water-blocking properties. These results indicate that the compounded ammonium polyphosphate and aluminum hydroxide at a specific mass ratio can improve the flame-retardant and water-blocking properties of the cable, with better results than using either alone. Furthermore, the amount of this compounded flame retardant added significantly affects the overall performance of the cable.

[0088] 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.

[0089] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A water-blocking copper-sheathed flexible fireproof cable, characterized in that, It includes the cable core, and from the inside out, the insulating layer, the copper sheath, and the outer sheath that are wrapped around the cable core. The outer sheath is made of polyethylene composite material. The polyethylene composite material is made through the following steps: Prepare the following raw materials by weight: 100 parts polyethylene resin, 15-25 parts compound flame retardant, 2-5 parts compatibilizer, 0.1-0.5 parts antioxidant, and 0.5-1 parts lubricant; mix the above raw materials and then extrude and granulate to obtain polyethylene composite material, wherein the extrusion temperature is 150-180℃.

2. The water-blocking copper-sheathed flexible fireproof cable according to claim 1, characterized in that, The compound flame retardant is composed of modified ammonium polyphosphate and aluminum hydroxide mixed in a mass ratio of 1:(0.5-2).

3. A water-blocking copper-sheathed flexible fireproof cable according to claim 2, characterized in that, The modified ammonium polyphosphate is prepared through the following steps: A sulfur-containing aminosilane coupling agent was mixed with anhydrous ethanol and stirred at 50°C for 30 min to obtain a sulfur-containing aminosilane coupling agent mixture. Ammonium polyphosphate was mixed with anhydrous ethanol and stirred at 60°C for 1 h to obtain an ammonium polyphosphate mixture. The sulfur-containing aminosilane coupling agent mixture and the ammonium polyphosphate mixture were mixed and stirred at 60°C for 1 h. The mixture was then filtered to obtain a solid product. The solid product was dried at 60°C for 3 h to obtain modified ammonium polyphosphate.

4. A water-blocking copper-sheathed flexible fireproof cable according to claim 3, characterized in that, The sulfur-containing aminosilane coupling agent is prepared by the following steps: γ-chloropropyltriethoxysilane, cystamine, potassium carbonate, potassium iodide, and anhydrous toluene were added to a dry reaction vessel. The vessel was subjected to nitrogen purging three times under ice bath conditions. The reaction was carried out at 80°C for 24 hours under N2 protection. After the reaction was completed, the inorganic salts were removed by suction filtration, the toluene was removed by rotary evaporation, and the vessel was dried under vacuum for 24 hours to obtain a sulfur-containing aminosilane coupling agent.

5. A water-blocking copper-sheathed flexible fireproof cable according to claim 3, characterized in that, The ratio of sulfur-containing aminosilane coupling agent to anhydrous ethanol in the sulfur-containing aminosilane coupling agent mixture is (1-3) g: 5 mL.

6. A water-blocking copper-sheathed flexible fireproof cable according to claim 3, characterized in that, The ratio of ammonium polyphosphate to anhydrous ethanol in the ammonium polyphosphate mixture is (6-10) g: 30 mL.

7. A water-blocking copper-sheathed flexible fireproof cable according to claim 4, characterized in that, The ratio of γ-chloropropyltriethoxysilane, cystamine, potassium carbonate, potassium iodide, and anhydrous toluene is 0.5 mol. 0.6mol: (1.4-1.6)mol: (0.04-0.06)mol: (500-700)mL.

8. A water-blocking copper-sheathed flexible fireproof cable according to claim 1, characterized in that, The insulating layer is made of polyester tape wrapped around it, with a thickness of 0.03-0.08 mm.

9. A water-blocking copper-sheathed flexible fireproof cable according to claim 1, characterized in that, The thickness of the copper sheath is 0.08-0.1 mm.

10. A method for preparing a water-blocking copper-sheathed flexible fire-resistant cable, characterized in that, The method for preparing the water-blocking copper-sheathed flexible fire-resistant cable according to any one of claims 1-9 includes the following steps: S1. The second copper wire is stranded into a conductor, and an insulating layer made of LDPE material is wrapped around the conductor using an extrusion die to obtain an insulated core wire; S2. Twist two insulated core wires together and wrap a shielding layer around the two insulated core wires to obtain the inner core unit; S3. Multiple inner core units are twisted together in a concentric twisting manner to obtain the cable inner core. An isolation layer is evenly wrapped around the cable inner core. A copper sheath is wrapped around the surface of the isolation layer. Then, a sheath made of polyethylene composite material is evenly wrapped around the copper sheath by extrusion to obtain a water-blocking copper sheath flexible fireproof cable.

Images