Cable insulation fireproof layer and preparation method and application thereof

Abstract

The invention provides a cable insulation fireproof layer and a preparation method and application thereof. The cable insulation fireproof layer comprises the following raw materials: 30-60 phr of silicone rubber, 30-50 phr of chloroprene rubber, 20-40 phr of polyethylene, 30-50 phr of a flame retardant, 10-30 phr of a boron nano material, 7-12 phr of a processing aid, 1-1.5 phr of an antioxidant, 5-10 phr of a plasticizer and 1-10 phr of a filler. The cable insulation fireproof layer provided by the invention has excellent fireproof and insulating properties. A flame retardant and a boron nitride nano material are added into a silicon rubber, chloroprene rubber and polyethylene ternary crosslinking system, so that the conductivity and flame retardance of the material are synergistically improved. The invention further provides a cable applying the insulating fireproof layer, the cable is particularly suitable for scenes such as high-rise buildings and data centers with high requirements for safety and intelligence, the cable is provided with a multi-layer composite fireproof structure and an integrated optical fiber sensing unit, and meanwhile the cable is resistant to interference, nontoxic and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of cable sheath materials technology, and in particular to a fireproof cable insulation layer. Background Technology

[0002] The safety performance of cables between buildings is of utmost importance. Existing building signal transmission cables have the following problems: insufficient fire resistance, as traditional flame-retardant cables easily release toxic fumes at high temperatures, failing to meet the high flame-retardant requirements of GB / T 19666-2019; immature condition detection functions, unable to detect cable temperature rise, insulation aging and other hidden dangers in real time, resulting in untimely fire warnings; and complex cable laying, occupying a large space and making construction difficult.

[0003] Fire-resistant cables are a type of cable that ensures the integrity of the circuit during a fire, guaranteeing continued normal power supply and signal transmission for an extended period even under high fire temperatures. Patent document CN119552432A mentions a fire-retardant cable with weak mechanical properties and average insulation performance; patent CN105837911B discloses an insulating thermally conductive cable material, which, while having good thermal conductivity, has poor corrosion resistance; patent CN106046464A mentions a cable sheath material with sufficient mechanical strength but somewhat poor flame retardancy. Therefore, this research aims to develop a fire-resistant cable insulation layer using a halogen-free flame retardant, possessing sufficient mechanical strength, and designing a cable suitable for use in high-safety environments such as buildings. Summary of the Invention

[0004] One objective of this invention is to address the insufficient fire resistance of traditional cables in inter-building structures by providing a fire-resistant insulation layer for cables. This layer uses a halogen-free flame retardant and employs silicone rubber, polyethylene, and neoprene rubber as a base, which greatly improves the flame retardancy of the rubber and allows it to remain usable even under high temperatures during a fire.

[0005] Another objective of this invention is to improve the anti-aging and corrosion resistance of cable insulation protective layers by incorporating boron nanomaterials, using silicone rubber, neoprene rubber, and adding additives; thereby enhancing the anti-aging and corrosion resistance of cable insulation protective layers.

[0006] Another objective of this invention is to provide a method for preparing a cable insulation protective layer, optimize the preparation method, and determine the preparation conditions for preparing the insulation protective layer using silicone rubber, polyethylene, and chloroprene rubber.

[0007] Another objective of this invention is to provide an intelligent fire-resistant and environmentally friendly signal transmission control and early warning cable for buildings, which solves the problems of insufficient fire resistance, inability to detect cable temperature rise and insulation aging in traditional building cables.

[0008] To achieve the above objectives, the present invention provides a fireproof insulation layer for cables, comprising the following raw materials by weight: 30-60 phr of silicone rubber, 30-50 phr of chloroprene rubber, 20-40 phr of polyethylene, 30-50 phr of flame retardant, and 10-30 phr of boron nanomaterials. Silicone rubber, with its Si-O bonds, is heat-resistant and decomposes to form a glassy silica layer, isolating oxygen and heat. Polyethylene, upon heating, decomposes to form carbonaceous residue, creating a porous carbon layer that blocks flame contact. Chloroprene rubber can capture free radicals, interrupting the combustion chain reaction. The combustion of chloroprene rubber and polyethylene forms a dense carbon layer, which, combined with the silica layer formed by the combustion of silicone rubber, creates a synergistic effect, forming a physical flame barrier. Flame retardants, after combustion, form stable oxides that combine with the dense carbon and silica layers, enhancing the flame-retardant effect of the physical barrier. Boron nanomaterials, with their sheet-like or cubic structure, can act as a framework embedded in the dense carbon, silica, and oxide systems, enhancing the system's mechanical strength and density, preventing further contact with oxygen and flame within the surface. Furthermore, the layered or cubic structure of boron nanomaterials allows heat to be rapidly conducted away along the lattice channels, improving overall high-temperature resistance and synergistically acting as a flame retardant in high-temperature environments.

[0009] Preferably, the insulating and fireproof layer comprises the following raw materials: 40-50 phr silicone rubber, 40-50 phr neoprene rubber, 25-35 phr polyethylene, 35-45 phr flame retardant, and 20-30 phr boron nanomaterials.

[0010] As a preferred embodiment, the insulating and fireproof layer also includes the following raw materials: 7-12 phr of processing aids, 1-1.5 phr of antioxidants, 5-10 phr of plasticizers, and 1-10 phr of fillers.

[0011] Preferably, the flame retardant is zinc borate (5-10 phr), aluminum hydroxide (25-40 phr), and the boron nanomaterial is boron nitride nanosheets. Zinc borate decomposes, absorbs heat, cools, and releases inert water vapor. The resulting zinc oxide and boron trioxide glassy layers can isolate oxygen and heat, synergistically blocking the flame with the silica produced by the decomposition of silicone rubber. Aluminum hydroxide dehydrates, absorbs heat, and generates alumina, which cools the flame. Simultaneously, the alumina coating inhibits smoke generation and, together with zinc oxide and silica, enhances the blocking effect. Boron nitride has excellent thermal conductivity, which can quickly disperse localized heat, reduce the material surface temperature, and delay thermal runaway. Furthermore, the layered structure of boron nitride can hinder the spread of flame and heat, delaying combustion.

[0012] Preferably, the processing aids are 3-5 phr of Li2O·AL2O3·nSiO2 flux, 2-4 phr of zinc oxide, 2-3 phr of stearic acid, and 1-3 phr of vulcanizing agent; the antioxidants are one or two of antioxidant 1010 and antioxidant 168; the plasticizers are one or more of epoxidized soybean oil, tributyl citrate, and acetylated tributyl citrate; and the filler is one of silica and carbon black.

[0013] The present invention also provides a method for preparing a fire-resistant layer for cable insulation, comprising the following steps: S1. Premix silicone rubber, polyethylene, and chloroprene rubber, and add plasticizer and antioxidant to obtain a premixed rubber compound; S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, boron nitride, zinc borate, zinc oxide, and stearic acid, and then mix. After mixing, add a vulcanizing agent and vulcanize to obtain the compound. S3. Pass the compound through a twin-screw extruder, then add flux and sinter to obtain a ceramicized rubber compound; S4. Cool to room temperature with water and coat the surface with boron nitride nanosheet slurry.

[0014] Preferably, the premixing temperature in step S1 is 60℃ and the time is 5-20 min; the mixing temperature in step S2 is 160-180℃ and the mixing time is 10-15 min, the vulcanization temperature is 160-170℃ and the vulcanization time is 8-12 min.

[0015] Preferably, the extrusion temperature in step S3 is 150-180℃, the sintering temperature is 200-250℃, and the sintering time is 5-10 minutes.

[0016] The present invention also provides an intelligent fireproof and environmentally friendly signal transmission control and early warning cable for buildings, comprising: a conductor, an insulating fireproof layer, a flame-retardant coating, a shielding layer with integrated optical fiber, an armor layer, and a low-smoke halogen-free sheath.

[0017] Preferably, the optical fiber and the conductor are spirally twisted in the same direction, with a bending radius ≤12D (D is the cable outer diameter). The optical fiber can ensure real-time monitoring of the cable status and provide early warning.

[0018] The fireproof cable insulation sleeve of the present invention has the following advantages: The fireproof cable insulation sleeve of the present invention is mainly composed of silicone rubber, polyethylene, and neoprene rubber, and the ternary blend system balances heat resistance and flexibility.

[0019] This invention incorporates a halogen-free flame retardant, which solves the problem of traditional flame-retardant cables releasing toxic fumes at high temperatures, and meets the high flame-retardant requirements of GB / T19666-2019.

[0020] This invention incorporates boron nitride nanosheets, which further improves the fire resistance rating, achieving a fire resistance rating of Class A and a smoke toxicity rating of AQ1 (optimal level), meeting the standards for cables used in building construction.

[0021] This invention provides an intelligent fireproof and environmentally friendly signal transmission control and early warning cable for buildings. The fiber optic temperature measurement accuracy is ±0.5℃, which can locate local hot spots within 1 meter. The integrated design reduces the laying cost by 30% and extends the service life to 25 years. Detailed Implementation

[0022] 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 should still be considered within the protection scope of the present invention.

[0023] General Implementation Examples A fireproof cable insulation layer comprises the following raw materials: silicone rubber 30-60 phr, chloroprene rubber 30-50 phr, polyethylene 20-40 phr, zinc borate 5-10 phr, aluminum hydroxide 25-40 phr, boron nanomaterials 10-30 phr, Li2O·AL2O3·nSiO2 flux 3-5 phr, zinc oxide 2-4 phr, stearic acid 2-3 phr, vulcanizing agent 1-3 phr, antioxidant 1-1.5 phr, plasticizer 5-10 phr, and filler 1-10 phr.

[0024] A method for preparing a fire-resistant insulation layer for cables includes the following steps: S1. Add silicone rubber, polyethylene, and chloroprene rubber to a mixer and mix at 60°C for 5-20 minutes at a mixing speed of 500-1000 rpm; then add plasticizer and antioxidant to obtain a premixed rubber compound. S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, zinc borate, zinc oxide, and stearic acid, and mix at a temperature of 160-180℃ for 10-15 minutes. Then add the vulcanizing agent and vulcanize at a temperature of 160-170℃ for 8-12 minutes to obtain the compound. S3. Pass the compound through a twin-screw extruder at an extrusion temperature of 150-180℃, add Li2O·AL2O3·nSiO2 flux and sinter at a sintering temperature of 200-250℃ for 5-10 minutes to obtain a ceramicized compound. S4. Cool to room temperature and coat the surface with boron nitride nanosheet slurry.

[0025] A smart fireproof and environmentally friendly signal transmission control and early warning cable for buildings, with a conductor made of tin-plated oxygen-free copper wire, a first layer wrapped with calcined mica tape, a second layer of fireproof insulation, a filler layer made of flame-retardant filler rope, a cabling wrapping layer made of halogen-free, low-smoke, and high-flame-retardant tape, an outer layer sprayed with boron nitride flame-retardant coating, a wrapping layer made of ceramicized halogen-free, low-smoke, and high-flame-retardant tape, optical fiber winding, an outer metal shielding layer, an outermost armor layer, and a low-smoke, halogen-free sheath.

[0026] Example 1 Insulating and fireproof layer ingredients: silicone rubber 30 phr, chloroprene rubber 30 phr, polyethylene 20 phr, zinc borate 5 phr, aluminum hydroxide 25 phr, boron nitride 20 phr, Li2O·AL2O3·nSiO2 cosolvent 3 phr, zinc oxide 2 phr, stearic acid 5 phr, vulcanizing agent 1 phr, antioxidant 1010 1 phr, epoxidized soybean oil 5 phr, carbon black 1 phr.

[0027] Preparation method: S1. Add silicone rubber, polyethylene, and chloroprene rubber to a mixer and mix at 60°C for 15 minutes at a mixing speed of 800 rpm; then add plasticizer and antioxidant to obtain a premixed rubber compound. S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, zinc borate, zinc oxide, and stearic acid, and mix at 170°C for 13 minutes. Then add the vulcanizing agent and vulcanize at 170°C for 10 minutes to obtain the compound. S3. The compound is passed through a twin-screw extruder at an extrusion temperature of 160℃. Li2O·AL2O3·nSiO2 flux is added and sintered at a sintering temperature of 230℃ for 10 minutes to obtain a ceramicized compound. S4. Cool to room temperature and coat the surface with boron nitride nanosheet slurry.

[0028] Example 2 Insulating and fireproof layer ingredients: silicone rubber 40 phr, chloroprene rubber 40 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0029] Preparation method: The preparation method of this example is the same as that of Example 1.

[0030] Example 3 Insulating and fireproof layer ingredients: silicone rubber 60 phr, chloroprene rubber 50 phr, polyethylene 40 phr, zinc borate 10 phr, aluminum hydroxide 40 phr, boron nitride 30 phr, Li2O·AL2O3·nSiO2 flux 5 phr, zinc oxide 4 phr, stearic acid 3 phr, vulcanizing agent 3 phr, antioxidant 1010 1.5 phr, epoxidized soybean oil 10 phr, carbon black 10 phr.

[0031] Preparation method: The preparation method of this example is the same as that of Example 1.

[0032] Example 4 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 25 phr, zinc borate 8 phr, aluminum hydroxide 35 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0033] Preparation method: The preparation method of this example is the same as that of Example 1.

[0034] Example 5 Insulating and fireproof layer ingredients: silicone rubber 50 phr, chloroprene rubber 50 phr, polyethylene 35 phr, zinc borate 8 phr, aluminum hydroxide 32 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1.5 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0035] Preparation method: The preparation method of this example is the same as that of Example 1.

[0036] Example 6 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0037] Preparation method: The preparation method of this example is the same as that of Example 1.

[0038] Example 7 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 38 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0039] Preparation method: The preparation method of this example is the same as that of Example 1.

[0040] Example 8 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 5 phr, aluminum hydroxide 25 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0041] Preparation method: The preparation method of this example is the same as that of Example 1.

[0042] Example 9 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 38 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1681 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0043] Preparation method: The preparation method of this example is the same as that of Example 1.

[0044] Example 10 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 38 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, tributyl citrate 8 phr, carbon black 5 phr.

[0045] Preparation method: The preparation method of this example is the same as that of Example 1.

[0046] Example 11 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 38 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, tributyl acetylacetonate 8 phr, carbon black 5 phr.

[0047] Preparation method: The preparation method of this example is the same as that of Example 1.

[0048] Example 12 Insulating and fireproof layer ingredients: silicone rubber 45 phr, chloroprene rubber 45 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 38 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 3 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, and silica 5 phr.

[0049] Preparation method: The preparation method of this example is the same as that of Example 1.

[0050] Table 1 Raw material ratios for Examples 1-12

[0051] Example 13 Ingredients: The ingredients in this embodiment are the same as those in embodiment 4.

[0052] Preparation method: includes the following steps: S1. Add silicone rubber, polyethylene, and chloroprene rubber to a mixer and mix at 60°C for 20 minutes at a mixing speed of 500 rpm; then add plasticizer and antioxidant to obtain a premixed rubber compound. S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, zinc borate, zinc oxide, and stearic acid, and mix at 160°C for 10 minutes. Then add the vulcanizing agent and vulcanize at 170°C for 12 minutes to obtain the compound. S3. The compound is passed through a twin-screw extruder at an extrusion temperature of 150°C. Li2O·AL2O3·nSiO2 flux is added and sintered at a sintering temperature of 200°C for 5 minutes to obtain a ceramicized compound. S4. Cool to room temperature and coat the surface with boron nitride nanosheet slurry.

[0053] Example 14 Ingredients: The ingredients in this embodiment are the same as those in embodiment 4.

[0054] Preparation method: includes the following steps: S1. Add silicone rubber, polyethylene, and chloroprene rubber to a mixer and mix at 60°C for 5 minutes at a mixing speed of 1000 rpm; then add plasticizer and antioxidant to obtain a premixed rubber compound. S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, zinc borate, zinc oxide, and stearic acid, and mix at 180°C for 10 minutes. Then add the vulcanizing agent and vulcanize at 160°C for 10 minutes to obtain the compound.

[0055] S3. The compound is passed through a twin-screw extruder at an extrusion temperature of 180℃. Li2O·AL2O3·nSiO2 flux is added and sintered at a sintering temperature of 250℃ for 10 minutes to obtain a ceramicized compound.

[0056] S4. Cool to room temperature and coat the surface with boron nitride nanosheet slurry.

[0057] Comparative Example 1 Insulating and fireproof layer ingredients: natural rubber 40 phr, chloroprene rubber 40 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0058] The absence of silicone rubber in this comparison may lead to a reduction in the self-extinguishing properties, high and low temperature resistance, and insulation of the matrix.

[0059] The preparation method is the same as in Example 1.

[0060] Comparative Example 2 Insulating and fireproof layer ingredients: silicone rubber 40 phr, natural rubber 40 phr, polyethylene 30 phr, boron zinc acid 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0061] The comparative ratio lacks chloroprene rubber, which may reduce the self-extinguishing property of the matrix and prevent it from forming a combined flame retardant system with aluminum hydroxide and zinc boride, thus reducing its flame retardant performance.

[0062] The preparation method is the same as in Example 1.

[0063] Comparative Example 3 Insulating and fireproof layer ingredients: silicone rubber 55 phr, chloroprene rubber 55 phr, boron zinc acid 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0064] The absence of polyethylene in this comparative ratio may lead to decreased insulation of the matrix, reduced mechanical properties, and increased susceptibility to cracking; at the same time, the flame retardant system may also be reduced, as polyethylene has a dilution effect and increases the risk of agglomeration of aluminum hydroxide and boron nitride.

[0065] The preparation method is the same as in Example 1.

[0066] Comparative Example 4 Insulating and fireproof layer ingredients: silicone rubber 40 phr, chloroprene rubber 40 phr, polyethylene 30 phr, zinc borate 8 phr, boron nitride 25 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0067] The comparison ratio lacks aluminum hydroxide, which may lead to a decrease in flame retardancy and a lack of smoke suppression effect.

[0068] The preparation method is the same as in Example 1.

[0069] Comparative Example 5 Insulating and fireproof layer ingredients: silicone rubber 40 phr, chloroprene rubber 40 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 30 phr, Li2O·AL2O3·nSiO2 flux 4 phr, zinc oxide 2 phr, stearic acid 2 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0070] The lack of boron nitride nanomaterials in this comparative example may lead to decreased thermal conductivity, decreased insulation, and decreased high-temperature resistance. Boron nitride has a high resistivity and forms a high-temperature insulation barrier in the system; its absence will cause the barrier to disappear.

[0071] The preparation method is the same as in Example 1.

[0072] Comparative Example 6 Insulating and fireproof layer ingredients: silicone rubber 40 phr, chloroprene rubber 40 phr, polyethylene 30 phr, zinc borate 8 phr, aluminum hydroxide 30 phr, boron nitride 25 phr, vulcanizing agent 2 phr, antioxidant 1010 1 phr, epoxidized soybean oil 8 phr, carbon black 5 phr.

[0073] The lack of processing aids in this comparative example will result in a partial reduction in the product performance and insufficient processing.

[0074] Testing and analysis.

[0075] Samples of the finished cable insulation fireproof layers prepared in Examples 1-14 and Comparative Examples 1-9 were taken and tested for their insulation, tensile properties, flame retardancy, and heat resistance. Insulation: The 1KV cable was tested according to GB / T3048.5-2007 "Test Methods for Electrical Properties of Wires and Cables Part 5: Determination of Insulation Resistance".

[0076] Tensile performance test: According to GB / T5054.2-2008: Performance requirements and test methods for high-performance sheathed cables; calculate the tensile strength change rate, tensile strength change rate = (initial strength - final strength) / initial strength × 100%.

[0077] Flame retardancy: The flame retardancy of the cable is evaluated according to the international standard IEC 60332, and a vertical burning test is conducted. According to the flammability rating: A (IEC 60332-3-21): The cable does not exhibit sustained vertical burning within 60 minutes; B (IEC 60332-3-22): Within a 40-minute test period, the cable bundle spreads no more than 3.5 meters, and no burning residue falls; C (IEC 60332-3-23): Within 20 minutes, the cable can burn, but the vertical spread distance must not exceed 2.5 meters, and no residue falls is acceptable; D (IEC 60332-3-24): The cable, once ignited individually, does not exhibit sustained burning, with no restrictions on vertical spread distance or time.

[0078] Table 2 Test results of Examples 1-14 Name / Project <![CDATA[Insulation (10 14 Ω / Km)]]> Tensile strength change rate (%) Flame retardant rating Example 1 4.9 -3.0 A Example 2 5.1 -1.4 A Example 3 6.7 -1.1 A Example 4 5.4 -1.6 A Example 5 6.5 -1.2 A Example 6 5.9 -2.3 A Example 7 5.8 -2.8 A Example 8 5.8 -1.8 A Example 9 5.9 -2.0 A Example 10 5.7 -2.2 A Example 11 5.8 -2.3 A Example 12 5.9 -2.1 A Example 13 5.3 -1.7 A Example 14 5.4 -1.5 A

[0079] As can be seen from the above test results, the embodiments 1-14 of the present invention all exhibit good performance in terms of insulation performance, tensile strength change rate, and flame retardant performance, and the flame retardant performance is all Grade A, indicating that these cables have high quality and reliability.

[0080] Example 3 showed the best performance. In the above examples, polyethylene and boron nitride materials played a significant role in insulation performance. By changing the amount of each added, the insulation performance of the material could be effectively adjusted. Boron nitride and the three matrix materials had a significant reinforcing effect on the mechanical properties of the material and could adjust the mechanical properties of the material.

[0081] Examples 4 and 13-14 are tests with different preparation conditions. The results show that the differences are not significant. The preparation conditions in these examples can all produce insulating protective layers with good performance.

[0082] Table 3 Performance test results for Comparative Examples 1-6

[0083] As can be seen from the results of Example 2 and Comparative Examples 1-6, Comparative Example 1 lacked silicone rubber. Silicone rubber has high Si-O bond energy and can still maintain insulation at high temperatures, which can ensure that it can still be used at high temperatures. After its absence, the insulation performance will decrease. The cross-linked network of silicone rubber can coat ATH / BN filler. After its absence, the filler-matrix interface debonds, and stress concentration leads to brittle fracture. It will also lead to a decrease in flame retardancy. Silicone rubber burns to form a silica ceramic layer, which isolates oxygen. After its absence, it will decrease.

[0084] Comparative Example 2 shows that the absence of chloroprene rubber leads to a decrease in flame retardancy. Without the skeleton formed by the carbonized layer, the resulting insulation layer is prone to cracking, resulting in a decrease in flame retardancy. The polar chlorine atoms of chloroprene rubber enhance the interfacial bonding force of the filler. Their absence makes the material prone to cracking under bending or vibration. In addition, the absence of chloroprene rubber also leads to a decrease in corrosion resistance.

[0085] Comparative Example 3 lacks polyethylene. The absence of polyethylene leads to a sharp drop in insulation performance. The non-polar CC chain insulation shield of polyethylene disappears, making it easier to break down under an electric field. After the flexible chain segment of polyethylene is missing, silicone rubber and neoprene rubber cannot make up for the rigidity gap. The flame retardant performance does not change much.

[0086] Comparative Example 4 lacked aluminum hydroxide, resulting in a significant decrease in mechanical properties, fluidity, and dispersibility. This led to a substantial impact on viscosity and fluidity during preparation, making extrusion difficult. The flame retardant properties also decreased significantly, as the absence of aluminum hydroxide dehydration to form alumina resulted in a decline in the overall performance of the fireproof layer.

[0087] In Comparative Example 5, the absence of boron nitride nanomaterials allows BN to form a rigid framework within the aggregate, effectively transferring stress. However, without it, fillers such as aluminum hydroxide tend to agglomerate, leading to stress concentration and interfacial debonding. As a high-temperature insulating barrier, the absence of BN results in a decrease in insulation performance. Furthermore, its flame-retardant properties also decline, as the physical shielding effect of BN disappears, accelerating flame spread.

[0088] The absence of additives in Comparative Example 6 leads to a decrease in various properties, and each component cannot achieve its optimal effect.

[0089] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fire-resistant insulation layer for cables, characterized in that, By weight, the insulating fireproof layer comprises the following raw materials: 30-60 phr of silicone rubber, 30-50 phr of chloroprene rubber, 20-40 phr of polyethylene, 30-50 phr of flame retardant, and 10-30 phr of boron nanomaterials.

2. The fireproof cable insulation layer according to claim 1, characterized in that, By weight, the insulating fireproof layer comprises the following materials: Silicone rubber 40-50 phr, chloroprene rubber 40-50 phr, polyethylene 25-35 phr, flame retardant 35-45 phr, boron nanomaterials 20-30 phr.

3. A fireproof cable insulation layer according to claim 1 or 2, characterized in that, By weight, the insulating fireproof layer also includes the following raw materials: 7-12 phr of processing aids, 1-1.5 phr of antioxidants, 5-10 phr of plasticizers, and 1-10 phr of fillers.

4. A fireproof cable insulation layer according to claim 1 or 2, characterized in that, The flame retardant is zinc borate 5-10 phr and aluminum hydroxide 25-40 phr; the boron nanomaterial is boron nitride nanosheets.

5. A fireproof cable insulation layer according to claim 1 or 2, characterized in that, The processing aids are flux (3-5 phr), zinc oxide (2-4 phr), stearic acid (2-3 phr), and vulcanizing agent (1-3 phr); the antioxidants are one or two of antioxidant 1010 and antioxidant 168; the plasticizers are one or more of epoxidized soybean oil, tributyl citrate, and acetylated tributyl citrate; and the fillers are one of silica and carbon black.

6. A method for preparing a fire-resistant insulation layer for cables, characterized in that, The fireproof cable insulation layer according to claim 1 includes the following steps: S1. Premix silicone rubber, polyethylene, and chloroprene rubber, and add plasticizer and antioxidant to obtain a premixed rubber compound; S2. Transfer the premixed rubber compound into an internal mixer, add aluminum hydroxide, zinc borate, zinc oxide, and stearic acid, and then mix. After mixing, add a vulcanizing agent and vulcanize to obtain the compound. S3. Pass the compound through a twin-screw extruder, then add flux and sinter to obtain a ceramicized rubber compound; S4. Cool to room temperature and coat the surface with boron nitride nanosheet slurry.

7. The method for preparing a fire-resistant cable insulation layer according to claim 6, characterized in that, The premixing temperature in step S1 is 60℃ and the time is 5-20 min; the mixing temperature in step S2 is 160-180℃ and the mixing time is 10-15 min; the vulcanization temperature is 160-170℃ and the vulcanization time is 8-12 min.

8. The method for preparing a fire-resistant cable insulation layer according to claim 6, characterized in that, The extrusion temperature in step S3 is 150-180℃, the sintering temperature is 200-250℃, and the sintering time is 5-10 minutes.

9. A smart fireproof and environmentally friendly signal transmission control and early warning cable for buildings, characterized in that, The cable insulation fireproof layer according to claim 1 is used. The cable includes the following parts: conductor, insulation fireproof layer, flame retardant coating, shielding layer with integrated optical fiber, armor layer, and low smoke halogen-free sheath.

10. The intelligent fireproof and environmentally friendly signal transmission control and early warning cable for buildings according to claim 9, characterized in that, The optical fiber and the conductor are spirally twisted in the same direction, with a bending radius ≤12D, where D is the outer diameter of the cable.

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