Environment-friendly fire-resistant cable based on phytic acid flame-retardant system and preparation method of environment-friendly fire-resistant cable

Abstract

The invention provides an environment-friendly fire-resistant cable based on a phytic acid flame-retardant system and a preparation method of the environment-friendly fire-resistant cable. The environment-friendly fire-resistant cable sequentially comprises a conductor from inside to outside; the phytic acid modified fireproof oxygen barrier layer contains 6wt%-8wt% of phytic acid-silane coupling agent composite adhesive; the phytic acid composite insulating layer contains 5wt%-7wt% of phytic acid-montmorillonite composite particles; modifying a filling body by phytic acid; the first wrapping layer contains 10 wt% of a phytic acid-magnesium hydroxide synergist; the second wrapping layer contains 3wt% of a phytic acid-magnesium hydroxide synergist; an inner sheath layer containing 6 wt%-8 wt% of phytic acid; and the outer protective layer contains 5wt%-7wt% of phytic acid. According to the invention, phytic acid is fused into each key structure layer of the cable in a modification and compounding manner, an oxygen isolation-flame retardation-insulation synergistic system can be constructed, the problems of fire resistance, environmental protection and aging resistance of a traditional cable are synchronously solved, and the cable has significant technical breakthrough value.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system and its preparation method. Background Technology

[0002] Fire-resistant cables are crucial for ensuring continuous power and signal transmission in extreme conditions such as fires. They are widely used in emergency power supply circuits for high-rise buildings, power transmission lines in subway tunnels, and fire protection power supply systems in large shopping malls—scenarios with stringent requirements for fire resistance, safety, and environmental protection. A typical fire-resistant cable structure, from the inside out, includes: conductor, insulation layer, fire-resistant layer, metal shielding layer (optional), filler layer, armor layer (optional), and outer sheath. The core of its fire-resistant performance lies in the design of the "fire-resistant layer." Currently, most mainstream fire-resistant layers utilize inorganic mineral materials, such as synthetic mica tape, ceramicized silicone rubber, or magnesium oxide powder, wrapped around the outer surface of the insulation layer. When the cable encounters high-temperature flames, these materials, relying on their inherent high-temperature resistance or the formation of a ceramic-like dense structure at high temperatures, maintain the integrity of the circuit for a certain period, thus achieving the "fire-resistant" function.

[0003] However, existing fire-resistant cables have three major defects: First, traditional fire-resistant oxygen-barrier layers rely on pure mica tape or ceramicized silicone rubber cloth, which are prone to moisture absorption and detachment at high temperatures, leading to insulation failure. The fire resistance time is mostly 60-90 minutes, which is difficult to meet the emergency power supply requirements of more than 120 minutes required by GB50217-2018. Second, the flame-retardant system of traditional outer sheath layers mostly uses halogenated flame retardants (such as chlorinated paraffin), which release toxic gases such as hydrogen chloride (often exceeding 200 ppm) when burning, hindering personnel evacuation and corroding equipment. Third, the flame retardancy of each structural layer of the cable (insulation layer, sheath, filler) is designed independently, lacking synergy, and the resistance to damp heat aging is poor. After aging for 1000 hours at 85℃ and 85% relative humidity, the mechanical properties are reduced by more than 20%.

[0004] In summary, although existing fire-resistant cables possess a certain degree of fire resistance, they still have significant shortcomings in terms of fire resistance continuity, structural reliability, environmental performance, and resistance to damp heat aging. There is an urgent need to develop a new type of fire-resistant cable with optimized structure, stable performance, and safety and environmental friendliness to meet increasingly stringent fire safety standards. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to provide an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system and its preparation method.

[0006] To achieve the above and other objectives, the present invention is implemented through the following technical solution: As a first aspect, the present invention provides an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, comprising a conductor, a phytic acid-modified fire-resistant oxygen barrier layer, and a phytic acid composite insulation layer, from the inside out; the phytic acid-modified fire-resistant oxygen barrier layer comprises 92wt%~94wt% ceramicized silicone rubber fireproof cloth and 6wt%~8wt% phytic acid-silane coupling agent composite adhesive; the phytic acid composite insulation layer comprises 90wt%~92wt% flame-retardant ceramicized polyolefin, 5wt%~7wt% phytic acid-montmorillonite composite particles, and 2wt%~3wt% antioxidant 1010; a phytic acid-modified filler fills the gaps between multiple conductors; a first wrapping layer is wrapped around the conductors with a phytic acid-synergistic ceramicized composite tape. The material consists of: an outer layer of phytic acid-modified filler; a second wrapping layer, which is made of phytic acid-modified glass fiber tape wrapped around the first wrapping layer; the phytic acid-modified glass fiber tape comprises 97 wt% glass fiber tape and 3 wt% phytic acid-magnesium hydroxide synergist; an inner sheath, extruded outside the second wrapping layer, the inner sheath material being composed of 85 wt%~88 wt% low-smoke halogen-free flame-retardant polyolefin, 6 wt%~8 wt% phytic acid, and 5 wt%~7 wt% intumescent flame retardant; and an outer sheath, extruded outside the inner sheath, the outer sheath material being composed of 90 wt%~92 wt% flame-retardant B1 grade polyolefin sheath material, 5 wt%~7 wt% phytic acid, and 3 wt%~5 wt% nano-aluminum hydroxide.

[0007] In one embodiment, the phytic acid modified refractory oxygen barrier layer is wrapped in 3 to 6 layers with a thickness of 0.3 mm to 0.9 mm.

[0008] In one embodiment, the thickness of the phytic acid composite insulating layer is 0.8 mm to 1.5 mm.

[0009] In one embodiment, the phytic acid modified filler contains glass fiber rope and phytic acid in a mass ratio of 95 wt% and 5 wt%, respectively.

[0010] In one embodiment, the first wrapping layer has a wrapping overlap rate of ≥35% and a thickness of 0.2mm~0.4mm; the second wrapping layer has a weaving density of 100% and a thickness of 0.1mm~0.2mm.

[0011] As a second aspect, the present invention provides a method for preparing an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, used to prepare the environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system as described in the first aspect, characterized in that it includes... Step 1: Preparation of conductor unit: Multiple electrolytic copper monofilaments with a diameter of 0.2mm~0.5mm and a tin plating thickness of 5μm~8μm are twisted into a conductor; 3~6 layers of phytic acid modified ceramicized silicone rubber fireproof cloth are layered and wrapped around the conductor to form a phytic acid modified fire-resistant oxygen barrier layer; then the insulating material is extruded through an extruder and wrapped around the phytic acid composite insulation layer to form a phytic acid composite insulation layer, thus obtaining the conductor. Step 2, stranding and filling: multiple wire cores are stranded together and phytic acid modified filler is filled into the gaps, with a filling density of ≥95%; wherein, the phytic acid modified filler is prepared by soaking glass fiber rope in phytic acid aqueous solution at room temperature for 1 hour and then drying it at 80°C for 1 hour. Step 3, preparation of the wrapping layer: The first wrapping layer is wrapped with phytic acid synergistic ceramicized composite tape outside the strand formed in Step 2, and the second wrapping layer is wrapped with phytic acid modified glass fiber tape. Step 4: Sheath preparation: The inner sheath and outer sheath are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer. After cooling and shaping, the finished cable is obtained.

[0012] In one embodiment, in step one, the preparation process of the phytic acid modified ceramicized silicone rubber fireproof cloth includes the following steps: mixing phytic acid and KH560 at a mass ratio of 1:1, stirring at 60°C for 1 hour, and cooling to form a phytic acid-silane coupling agent composite adhesive; immersing the ceramicized silicone rubber fireproof cloth in the phytic acid-silane coupling agent composite adhesive at 60°C for 10 minutes; and taking out the impregnated ceramicized silicone rubber fireproof cloth and drying it at 120°C for 2 hours.

[0013] In one embodiment, in step one, the preparation process of the insulating material includes the following steps: dissolving phytic acid and organomontmorillonite in ethanol at a mass ratio of 1:2, ultrasonically dispersing for 30 minutes, and then drying at 80°C to obtain phytic acid-montmorillonite composite particles; and mixing 90wt%~92wt% flame-retardant ceramicized polyolefin, 5wt%~7wt% phytic acid-montmorillonite composite particles, and 2wt%~3wt% antioxidant 1010 to obtain the insulating material.

[0014] In one embodiment, in step three, the preparation process of the phytic acid synergistic ceramicized composite tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant is added, and the mixture is stirred at high temperature for 20 minutes to obtain a phytic acid-magnesium hydroxide synergist; using the ceramicized composite tape as a substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating-drying integrated process, with a single-sided coating thickness of 0.02mm~0.08mm, pre-baking at 80℃ for 10 minutes in the first stage, and curing at 110℃ for 20 minutes in the second stage.

[0015] In one embodiment, in step three, the preparation process of the phytic acid modified glass fiber tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant is added, and the mixture is stirred at high temperature for 20 minutes to obtain a phytic acid-magnesium hydroxide synergist; using alkali-free glass fiber tape as the substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating process, with a single-sided coating thickness of 0.02mm~0.08mm, and dried at 100℃ for 15 minutes.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Phytic acid (inositol hexaphosphate), as a natural organophosphorus flame retardant, contains six active phosphate groups. During combustion, it catalyzes the formation of a dense char layer in polymer materials, while being smokeless and non-toxic (halogen content ≤300ppm). It also exhibits excellent compatibility with ceramicized silicone rubber, polyolefins, and other materials. This invention utilizes modified and composite methods to integrate phytic acid into key structural layers of cables, constructing a synergistic "oxygen barrier-flame retardant-insulation" system. This simultaneously addresses the fire resistance, environmental friendliness, and aging resistance issues of traditional cables, demonstrating significant technological breakthrough value. 2. The fire-resistant cable provided by this invention features a full-layer halogen-free design, with hydrogen chloride release ≤30ppm and smoke density rating (SDR) ≤40 during combustion; 3. The fire-resistant cable provided by this invention improves fire resistance through a multi-layer structure, ensuring continuous power supply for ≥180 minutes in a flame of 950~1000℃, and maintaining insulation (insulation resistance ≥100MΩ) after water spraying / impact vibration, far exceeding the 120-minute fire resistance standard of traditional cables. 4. The fire-resistant cable provided by this invention improves the cable's resistance to damp heat aging. After aging for 1000 hours at 85°C and 85% RH, the sheath layer tensile strength loss rate is ≤12% and the elongation at break loss rate is ≤15%, which is better than the performance loss of traditional cables by more than 20%. 5. The fire-resistant cable provided by this invention has the following electrical properties: conductor DC resistance ≤ 4.8Ω / km (2.5mm² cross-sectional area), overall cable breakdown field strength ≥ 32kV / mm, and bending radius ≤ 6D (D is the cable outer diameter), meeting the long-term stable operation requirements of critical scenarios. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system according to the present invention. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0019] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0020] In this invention, the serial numbers assigned to components, such as "first," "second," etc., are merely used to distinguish the described objects and have no sequential or technical meaning. The terms "an," "a," or "the," etc., used in this invention do not indicate a quantity limitation, but simply indicate the presence of at least one. The term "connection," unless otherwise specified, includes both direct and indirect connections. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, encompassing not only the listed elements but also other elements not expressly listed.

[0021] To avoid confusion with the present invention, some technical features known in the art have not been described.

[0022] Please see Figure 1 The present invention provides an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, comprising, from the inside out, a core 10, a phytic acid modified filler 20, a first wrapping layer 30, a second wrapping layer 40, an inner sheath 50, and an outer sheath 60.

[0023] Each core 10 comprises, from the inside out, a conductor 11, a phytic acid-modified fire-resistant oxygen barrier layer 12, and a phytic acid composite insulation layer 13. The environmentally friendly fire-resistant cable shown in this embodiment has a total of five cores 10. One core 10 is located at the center of the cable, and the other four cores 10 are arranged in a circular array around the central core 10, and are tangent to the central core 10.

[0024] Specifically, the conductor 11 is made of electrolytic copper monofilaments with a purity of 99.99% and a diameter of 0.2mm to 0.5mm (with a tin plating thickness of 5μm to 8μm) twisted into a bundle (with a cross-sectional area of ​​2.5mm² to 25mm²).

[0025] The phytic acid-modified fire-resistant oxygen barrier layer 12 is made by wrapping the conductor 11 with phytic acid-modified ceramicized silicone rubber fireproof cloth. The wrapping method is layer-by-layer (3 to 6 layers), and the wrapping thickness is 0.3 mm to 0.9 mm. Specifically, the preparation process of the phytic acid-modified ceramicized silicone rubber fireproof cloth is as follows: First, phytic acid and KH560 are mixed at a mass ratio of 1:1 and stirred at 60°C for 1 hour, and then cooled to form a phytic acid-silane coupling agent composite adhesive; then, the ceramicized silicone rubber fireproof cloth is immersed in the phytic acid-silane coupling agent composite adhesive for 10 minutes at 60°C; finally, the immersed ceramicized silicone rubber fireproof cloth is taken out and dried at 120°C for 2 hours to obtain the phytic acid-modified ceramicized silicone rubber fireproof cloth (wherein, the mass ratio of the ceramicized silicone rubber fireproof cloth and the phytic acid-silane coupling agent composite adhesive is 92wt% to 94wt% and 6wt% to 8wt%, respectively). At high temperatures, phytic acid can catalyze the formation of a dense SiO-carbon composite layer in silicone rubber, thereby increasing the oxygen barrier efficiency by 40%.

[0026] The phytic acid composite insulation layer 13 is extruded outside the phytic acid modified fire-resistant oxygen barrier layer 12. The insulation material consists of 90wt%~92wt% flame-retardant ceramicized polyolefin (HPCC), 5wt%~7wt% phytic acid-montmorillonite composite particles, and 2wt%~3wt% antioxidant 1010. The phytic acid-montmorillonite composite particles are a white powder, prepared by dissolving phytic acid and organomontmorillonite in ethanol at a mass ratio of 1:2, ultrasonically dispersing for 30 minutes, and then drying at 80℃. The thickness of the phytic acid composite insulation layer 13 is 0.8mm~1.5mm; the dielectric loss value (1kHz) is ≤0.004, and the temperature resistance range is -40℃~150℃.

[0027] The conductor core 10 improves the high-temperature oxidation resistance of the conductor through the tin-plated layer, the fire-resistant oxygen barrier layer of the phytic acid system, and the insulation layer, thus preventing the copper conductor from oxidizing and melting at temperatures above 900°C.

[0028] The phytic acid modified filler 20 fills the gaps between multiple wire cores 10 with a filling density of ≥95%, which is used to avoid oxygen residue and improve the overall flame retardancy. The phytic acid modified filler 20 is prepared by soaking glass fiber rope (95wt%) in phytic acid aqueous solution (5wt%) at room temperature for 1 hour, and then drying it at 80℃ for 1 hour.

[0029] The first wrapping layer 30 is wrapped around the core 10 and the phytic acid modified filler 20 with a phytic acid synergistic ceramicized composite tape. The wrapping overlap rate is ≥35%, the thickness is 0.2mm~0.4mm, and the shielding effectiveness (30~1000MHz) is ≥85dB. Specifically, the preparation process of the phytic acid synergistic ceramicized composite tape (wherein the mass ratio of the ceramicized composite tape to the phytic acid-magnesium hydroxide synergist is 90wt% and 10wt%, respectively) is as follows: using ceramicized refractory silicone rubber composite tape or ceramicized glass fiber composite tape as the substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating-drying integrated process. The single-sided coating thickness is 0.02mm~0.08mm. The first stage is pre-baked at 80℃ for 10min, and the second stage is cured at 110℃ for 20min to ensure that the residual moisture content is ≤1.0wt%. At high temperature, phytic acid promotes the decomposition and endothermic reaction of magnesium hydroxide, which works synergistically with the ceramicized layer to block flames. The preparation process of the phytic acid-magnesium hydroxide synergist is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant (polyethylene glycol 400) is added, and the mixture is stirred at high temperature for 20 minutes.

[0030] The second wrapping layer 40 is made of phytic acid modified glass fiber tape wrapped around the first wrapping layer 30, with a weaving density of 100% and a thickness of 0.1mm~0.2mm, to improve the cable's tear resistance and secondary oxygen barrier effect. Specifically, the preparation process of the phytic acid modified glass fiber tape (wherein the mass ratio of glass fiber tape to phytic acid-magnesium hydroxide synergist is 97wt% and 3wt%, respectively) is as follows: using alkali-free glass fiber tape as the substrate, a roller coating process (coating roller speed 15r / min~20r / min) is used to coat the surface with phytic acid-magnesium hydroxide synergist, with a single-sided coating thickness of 0.02mm~0.08mm, and drying at 100℃ for 15min.

[0031] The inner protective layer 50 is extruded outside the second wrapping layer 40, with a thickness of 0.9mm~1.6mm, a UL94 rating of V-0, and an oxygen index ≥38%. The inner protective layer material is composed of 85wt%~88wt% low-smoke halogen-free flame-retardant polyolefin, 6wt%~8wt% phytic acid, and 5wt%~7wt% intumescent flame retardant (APP / PER mass ratio 3:1), and is melt-blended and extruded using a twin-screw extruder (160℃~180℃).

[0032] The outer sheath 60 is extruded outside the inner sheath 50 at an extrusion temperature of 170℃~190℃ and has a thickness of 2.0mm~3.6mm. The outer sheath material consists of 90wt%~92wt% flame-retardant B1 grade polyolefin sheath material, 5wt%~7wt% phytic acid, and 3wt%~5wt% nano-aluminum hydroxide. After phytic acid modification, the scratch resistance of this layer is improved by 25%, and there is no halogen release during combustion (halogen element content ≤200ppm).

[0033] Optionally, in order to isolate the cable from direct contact with the inner wall edge of the reserved hole in the cable trench and to protect the outer surface of the environmentally friendly fire-resistant cable from wear, wear-resistant components 70 can be symmetrically arranged outside the outer sheath 60. The wear-resistant components 70 may include rubber pads, adhesive blocks, etc. For specific structural design, please refer to the wear-resistant component design in an isolation-type mineral-insulated fire-resistant cable provided by Chinese Patent Publication No. CN120496937B.

[0034] Furthermore, this invention also provides a method for preparing an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, specifically comprising: Step 1: Preparation of conductor unit: Multiple electrolytic copper monofilaments with a diameter of 0.2mm~0.5mm and a tin plating thickness of 5μm~8μm are twisted into conductor 11; 3~6 layers of phytic acid modified ceramicized silicone rubber fireproof cloth (0.3mm~0.9mm thickness) are layered and wrapped around the conductor 11 to form phytic acid modified fire-resistant oxygen barrier layer 12; then, the insulating material is extruded through an extruder (extrusion temperature 190℃~200℃) and wrapped around the phytic acid modified fire-resistant oxygen barrier layer 12 to form phytic acid composite insulation layer 13 (thickness 0.8mm~1.5mm), thus obtaining conductor 10; The preparation process of the phytic acid modified ceramicized silicone rubber fireproof cloth includes the following steps: mixing phytic acid and KH560 at a mass ratio of 1:1, stirring at 60°C for 1 hour, and cooling to form a phytic acid-silane coupling agent composite adhesive; immersing the ceramicized silicone rubber fireproof cloth in the phytic acid-silane coupling agent composite adhesive at 60°C for 10 minutes; removing the impregnated ceramicized silicone rubber fireproof cloth and drying it at 120°C for 2 hours. The mass percentages of the ceramicized silicone rubber fireproof cloth and the phytic acid-silane coupling agent composite adhesive in the prepared phytic acid modified ceramicized silicone rubber fireproof cloth are 92wt%~94wt% and 6wt%~8wt%, respectively.

[0035] The preparation process of the insulating material includes the following steps: phytic acid and organomontmorillonite are dissolved in ethanol at a mass ratio of 1:2 and ultrasonically dispersed for 30 min, then dried at 80℃ to obtain phytic acid-montmorillonite composite particles; 90wt%~92wt% flame-retardant ceramicized polyolefin (HPCC), 5wt%~7wt% phytic acid-montmorillonite composite particles and 2wt%~3wt% antioxidant 1010 are mixed to obtain the insulating material.

[0036] Step 2, Stranding and Filling: Strand multiple core wires 10 together and fill the gaps with phytic acid modified filler 20, with a filling density ≥95%; The phytic acid modified filler 20 is prepared by soaking glass fiber rope in phytic acid aqueous solution at room temperature for 1 hour and then drying it at 80°C for 1 hour. The mass ratio of glass fiber rope and phytic acid in the prepared phytic acid modified filler 20 is 95wt% and 5wt%, respectively.

[0037] Step 3, preparation of the wrapping layer: The first wrapping layer 30 (wrapping overlap rate ≥35%, thickness 0.2mm~0.4mm) is wrapped with phytic acid synergistic ceramicized composite tape and the second wrapping layer 40 (weaving density 100%, thickness 0.1mm~0.2mm) is wrapped with phytic acid modified glass fiber tape in sequence outside the strand formed in step 2. The preparation process of the phytic acid synergistic ceramicized composite tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant (polyethylene glycol 400) is added, and the mixture is stirred at high temperature for 20 minutes to obtain a phytic acid-magnesium hydroxide synergist; using a ceramicized composite tape (e.g., a ceramicized refractory silicone rubber composite tape or a ceramicized glass fiber composite tape) as the substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating-drying integrated process, with a single-sided coating thickness of 0.02mm~0.08mm, pre-baking at 80℃ for 10 minutes in the first stage, and curing at 110℃ for 20 minutes in the second stage. The mass ratio of the ceramicized composite tape and the phytic acid-magnesium hydroxide synergist in the obtained phytic acid synergistic ceramicized composite tape is 90wt% and 10wt%, respectively.

[0038] The preparation process of the phytic acid modified glass fiber tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant (polyethylene glycol 400) is added, and the mixture is stirred at high temperature for 20 minutes to obtain a phytic acid-magnesium hydroxide synergist; using alkali-free glass fiber tape as the substrate, a roller coating process (coating roller speed 15r / min~20r / min) is used to coat the surface of the phytic acid-magnesium hydroxide synergist, with a single-sided coating thickness of 0.02mm~0.08mm, and drying at 100℃ for 15 minutes. The mass ratio of glass fiber tape and phytic acid-magnesium hydroxide synergist in the obtained phytic acid modified glass fiber tape is 97wt% and 3wt%, respectively.

[0039] Step 4: Sheath preparation: The inner sheath 50 (extrusion temperature 160℃~180℃, for example 170℃) and the outer sheath 60 (extrusion temperature 170℃~190℃, for example 180℃) are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer 40. After cooling and shaping, the finished cable is obtained.

[0040] Example 1: An embodiment of the present invention provides an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system. The preparation method of the environmentally friendly fire-resistant cable based on the phytic acid flame-retardant system includes: S1: Nineteen electrolytic copper monofilaments with a diameter of 0.3 mm and a tin plating thickness of 6 μm are twisted together to form a conductor 11 with a cross-sectional area of ​​2.5 mm². Phytic acid-modified ceramicized silicone rubber fireproof cloth (wherein the mass ratio of ceramicized silicone rubber fireproof cloth and phytic acid-silane coupling agent composite adhesive is 93 wt% and 7 wt%, respectively) is layered and wrapped around the conductor 11 in five layers with a wrapping thickness of 0.6 mm to form a phytic acid-modified fire-resistant oxygen barrier layer 12. Then, an insulating material (91 wt% HPCC, 6 wt% phytic acid-montmorillonite composite particles, and 3 wt% antioxidant 1010) is extruded through an extruder (extrusion temperature 200℃) and coated onto the phytic acid-modified fire-resistant oxygen barrier layer 12 to form a phytic acid composite insulating layer 13 (thickness of 1.2 mm), thus obtaining the wire core 10. S2. Twist the five core wires 10 together and fill the gaps with phytic acid modified filler 20 (phytic acid content 5wt%), with a filling density of 96%. S3. In sequence, the first wrapping layer 30 (wrapping overlap rate 35%, wrapping thickness 0.3mm) is wrapped with phytic acid synergistic ceramicized composite tape (phytic acid-magnesium hydroxide synergist content 10wt%) and the second wrapping layer 40 (weaving density 100%, wrapping thickness 0.15mm) is wrapped with phytic acid modified glass fiber tape (phytic acid-magnesium hydroxide synergist content 3wt%). S4. The inner sheath 50 (composed of 87wt% low-smoke halogen-free flame-retardant polyolefin, 7wt% phytic acid and 6wt% APP / PER; extrusion temperature 170℃, thickness 1.2mm) and the outer sheath 60 (composed of 91wt% flame-retardant B1 grade polyolefin sheath material, 6wt% phytic acid and 3wt% nano aluminum hydroxide; extrusion temperature 180℃, thickness 2.5mm) are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer 40. After cooling and shaping, the finished cable is obtained.

[0041] Example 2: An embodiment of the present invention provides an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system. The preparation method of the environmentally friendly fire-resistant cable based on the phytic acid flame-retardant system includes: S1: Nineteen electrolytic copper monofilaments with a diameter of 0.3 mm and a tin plating thickness of 6 μm are twisted together to form a conductor 11 with a cross-sectional area of ​​2.5 mm². Phytic acid-modified ceramicized silicone rubber fireproof cloth (with the ceramicized silicone rubber fireproof cloth and phytic acid-silane coupling agent composite adhesive accounting for 94 wt% and 6 wt% respectively) is layered and wrapped around the conductor 11 in three layers with a wrapping thickness of 0.3 mm to form a phytic acid-modified fire-resistant oxygen barrier layer 12. Then, an insulating material (94 wt% HPCC, 5 wt% phytic acid-montmorillonite composite particles, and 1 wt% antioxidant 1010) is extruded through an extruder (extrusion temperature 200℃) and coated onto the phytic acid-modified fire-resistant oxygen barrier layer 12 to form a phytic acid composite insulation layer 13 (thickness of 0.8 mm), thus obtaining the wire core 10. S2. Twist the five core wires 10 together and fill the gaps with phytic acid modified filler 20 (phytic acid content 5wt%), with a filling density of 96%. S3. In sequence, the first wrapping layer 30 (wrapping overlap rate 35%, wrapping thickness 0.2mm) is wrapped with phytic acid synergistic ceramicized composite tape (phytic acid-magnesium hydroxide synergist content 10wt%) and the second wrapping layer 40 (weaving density 100%, wrapping thickness 0.15mm) is wrapped with phytic acid modified glass fiber tape (phytic acid-magnesium hydroxide synergist content 3wt%). S4. The inner sheath 50 (composed of 88wt% low-smoke halogen-free flame-retardant polyolefin, 6wt% phytic acid and 6wt% APP / PER; extrusion temperature 170℃, thickness 0.9mm) and the outer sheath 60 (composed of 92wt% flame-retardant B1 grade polyolefin sheath material, 5wt% phytic acid and 3wt% nano aluminum hydroxide; extrusion temperature 180℃, thickness 2.0mm) are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer 40. After cooling and shaping, the finished cable is obtained.

[0042] Example 3: An embodiment of the present invention provides an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system. The preparation method of the environmentally friendly fire-resistant cable based on the phytic acid flame-retardant system includes: S1: Nineteen electrolytic copper monofilaments with a diameter of 0.3 mm and a tin plating thickness of 6 μm are twisted together to form a conductor 11 with a cross-sectional area of ​​2.5 mm². Phytic acid-modified ceramicized silicone rubber fireproof cloth (with the ceramicized silicone rubber fireproof cloth and phytic acid-silane coupling agent composite adhesive accounting for 92 wt% and 8 wt% respectively) is layered and wrapped around the conductor 11 in six layers with a thickness of 0.9 mm to form a phytic acid-modified fire-resistant oxygen barrier layer 12. Then, an insulating material (90 wt% HPCC, 7 wt% phytic acid-montmorillonite composite particles, and 3 wt% antioxidant 1010) is extruded through an extruder (extrusion temperature 200℃) and coated onto the phytic acid-modified fire-resistant oxygen barrier layer 12 to form a phytic acid composite insulation layer 13 (1.5 mm thick), thus obtaining the wire core 10. S2. Twist the five core wires 10 together and fill the gaps with phytic acid modified filler 20 (phytic acid content 5wt%), with a filling density of 96%. S3. In sequence, the first wrapping layer 30 (wrapping overlap rate 40%, wrapping thickness 0.4mm) is wrapped with phytic acid synergistic ceramicized composite tape (phytic acid-magnesium hydroxide synergist content 10wt%) and the second wrapping layer 40 (weaving density 100%, wrapping thickness 0.15mm) is wrapped with phytic acid modified glass fiber tape (phytic acid-magnesium hydroxide synergist content 3wt%). S4. The inner sheath 50 (composed of 85wt% low-smoke halogen-free flame-retardant polyolefin, 8wt% phytic acid and 7wt% APP / PER; extrusion temperature 170℃, thickness 1.6mm) and the outer sheath 60 (composed of 90wt% flame-retardant B1 grade polyolefin sheath material, 7wt% phytic acid and 3wt% nano aluminum hydroxide; extrusion temperature 180℃, thickness 3.6mm) are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer 40. After cooling and shaping, the finished cable is obtained.

[0043] Comparative Example 1: The difference from Example 1 is that in step S1, the phytic acid modified refractory oxygen barrier layer 12 uses phytic acid modified ceramicized silicone rubber fireproof cloth, and the mass ratio of ceramicized silicone rubber fireproof cloth and phytic acid-silane coupling agent composite adhesive are 97wt% and 3wt%, respectively.

[0044] Comparative Example 2: The difference from Example 1 is that in step S4, the inner sheath material of the inner sheath 50 is composed of 82 wt% low smoke halogen-free flame retardant polyolefin, 12 wt% phytic acid and 6 wt% APP / PER.

[0045] Comparative Example 3: The difference from Example 1 is that the wrapping thickness of the first wrapping layer 30 in step S3 is 0.1 mm.

[0046] Comparative Example 4: The difference from Example 1 is that in step S1, a fire-resistant oxygen barrier layer is wrapped with pure ceramicized silicone rubber fireproof cloth that has not been modified with phytic acid.

[0047] Comparative Example 5: The difference from Example 1 is that pure HPCC was used as the insulating material to extrude the insulating layer in step S1; and pure flame-retardant B1 grade polyolefin sheath material was used to extrude the outer sheath in step S4.

[0048] Comparative Example 6: The difference from Example 1 is that: in step S1, a fire-resistant and oxygen-barrier layer is wrapped with pure ceramicized silicone rubber fireproof cloth without phytic acid modification; an insulation layer is extruded using pure HPCC as the insulating material; in step S2, pure glass fiber rope is used as the filler; in step S3, a first wrapping layer is wrapped with pure ceramicized composite tape, and a second wrapping layer is wrapped with pure glass fiber tape; in step S4, an inner protective layer is extruded using low-smoke halogen-free flame-retardant polyolefin, and an outer protective layer is extruded using pure flame-retardant B1 grade polyolefin sheath material.

[0049] Testing and Analysis: The finished cables prepared in Examples 1-3 and Comparative Examples 1-6 were tested using standard methods under a unified testing environment (temperature 25±2℃, humidity 50±5%) for fire resistance time (refer to standard GB / T 19216.21-2022), flame retardancy rating (UL94), smoke density rating (SDR, reference standard GB / T 8323.2-2008), hydrogen chloride release (refer to standard GB / T 17650.1-1998), wet heat aging mechanical loss rate (refer to standard GB / T 2951.12-2008), and room temperature breakdown field strength (refer to standard GB / T 1408.1-2016). The test results are shown in Table 1. Table 1. Performance test results of the finished cables obtained in each embodiment and comparative example. ; As shown in Table 1, the finished cables prepared in Examples 1-3, due to the appropriate amount of phytic acid modification throughout the entire layer, form a multi-layered "oxygen barrier-flame retardant-insulation" protective system, consistently meeting the performance requirements of fire resistance time ≥180 min, hydrogen chloride release ≤30 ppm, and room temperature breakdown field strength ≥32 kV / mm. In Comparative Example 1, the phytic acid-silane coupling agent composite adhesive content in the phytic acid-modified ceramicized silicone rubber fireproof cloth used in the phytic acid-modified fire-resistant oxygen barrier layer was <6 wt%, resulting in the finished cable failing to meet the standards for fire resistance time, environmental protection, and electrical performance. In Comparative Example 2, although the fire resistance time met the standard due to the addition of more than 8 wt% phytic acid in the inner sheath, the mechanical properties of the inner sheath deteriorated: tensile strength decreased by 25%, and elongation at break decreased by 30%. In Comparative Example 3, the thickness of the first wrapping layer was less than 0.2 mm, resulting in a shielding effectiveness of 65 dB (below the standard of 85 dB) and a fire resistance time of less than 180 min. The test results of Comparative Examples 4 to 6 proved that the fire resistance performance of the oxygen barrier layer without phytic acid modification will decrease by 30%, and the insulation layer and outer sheath without phytic acid modification will lead to the comprehensive deterioration of electrical, environmental and aging performance, and the failure of the synergistic system. Therefore, phytic acid modification is the core of achieving the performance standard, and multiple layers need to be used in combination to achieve the synergistic effect.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, characterized in that, include: The wire core comprises, from the inside out, a conductor, a phytic acid-modified fire-resistant oxygen barrier layer, and a phytic acid composite insulation layer; the phytic acid-modified fire-resistant oxygen barrier layer comprises 92wt%~94wt% ceramicized silicone rubber fireproof cloth and 6wt%~8wt% phytic acid-silane coupling agent composite adhesive; the phytic acid composite insulation layer comprises 90wt%~92wt% flame-retardant ceramicized polyolefin, 5wt%~7wt% phytic acid-montmorillonite composite particles, and 2wt%~3wt% antioxidant 1010; Phytic acid-modified filler is used to fill the gaps between the multiple said wire cores; The first wrapping layer is wrapped around the core and the phytic acid modified filler body with a phytic acid synergistic ceramic composite tape; the phytic acid synergistic ceramic composite tape comprises 90wt% ceramic composite tape and 10wt% phytic acid-magnesium hydroxide synergist. The second wrapping layer is made of phytic acid modified glass fiber tape wrapped around the first wrapping layer; the phytic acid modified glass fiber tape comprises 97wt% glass fiber tape and 3wt% phytic acid-magnesium hydroxide synergist. The inner protective layer is extruded outside the second wrapping layer. The inner protective layer material is composed of 85wt%~88wt% low smoke halogen-free flame retardant polyolefin, 6wt%~8wt% phytic acid and 5wt%~7wt% intumescent flame retardant. The outer sheath is extruded outside the inner sheath. The outer sheath material consists of 90wt%~92wt% flame-retardant B1 grade polyolefin sheath material, 5wt%~7wt% phytic acid and 3wt%~5wt% nano aluminum hydroxide.

2. The environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system according to claim 1, characterized in that, The phytic acid-modified refractory oxygen barrier layer is wrapped in 3 to 6 layers with a thickness of 0.3 mm to 0.9 mm.

3. The environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system according to claim 1, characterized in that, The thickness of the phytic acid composite insulation layer is 0.8mm to 1.5mm.

4. The environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system according to claim 1, characterized in that, The phytic acid modified filler contains glass fiber rope and phytic acid in a mass ratio of 95 wt% and 5 wt%, respectively.

5. The environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system according to claim 1, characterized in that, The first wrapping layer has a wrapping overlap rate of ≥35% and a thickness of 0.2mm~0.4mm; the second wrapping layer has a weaving density of 100% and a thickness of 0.1mm~0.2mm.

6. A method for preparing an environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system, used to prepare the environmentally friendly fire-resistant cable based on a phytic acid flame-retardant system as described in any one of claims 1 to 5, characterized in that, include: Step 1: Preparation of conductor unit: Multiple electrolytic copper monofilaments with a diameter of 0.2mm~0.5mm and a tin plating thickness of 5μm~8μm are twisted into a conductor; 3~6 layers of phytic acid modified ceramicized silicone rubber fireproof cloth are layered and wrapped around the conductor to form a phytic acid modified fire-resistant oxygen barrier layer; then the insulating material is extruded through an extruder and wrapped around the phytic acid modified fire-resistant oxygen barrier layer to form a phytic acid composite insulation layer, thus obtaining the conductor. Step 2, stranding and filling: multiple wire cores are stranded together and phytic acid modified filler is filled into the gaps, with a filling density of ≥95%; wherein, the phytic acid modified filler is prepared by soaking glass fiber rope in phytic acid aqueous solution at room temperature for 1 hour and then drying it at 80°C for 1 hour. Step 3, preparation of the wrapping layer: The first wrapping layer is wrapped with phytic acid synergistic ceramicized composite tape outside the strand formed in Step 2, and the second wrapping layer is wrapped with phytic acid modified glass fiber tape. Step 4: Sheath preparation: The inner sheath and outer sheath are extruded separately using a twin-screw extruder and wrapped around the second wrapping layer. After cooling and shaping, the finished cable is obtained.

7. The preparation method according to claim 6, characterized in that, In step one, the preparation process of the phytic acid modified ceramicized silicone rubber fireproof cloth includes the following steps: mixing phytic acid and KH560 at a mass ratio of 1:1, stirring at 60°C for 1 hour, and cooling to form a phytic acid-silane coupling agent composite adhesive; immersing the ceramicized silicone rubber fireproof cloth in the phytic acid-silane coupling agent composite adhesive at 60°C for 10 minutes; and drying the impregnated ceramicized silicone rubber fireproof cloth at 120°C for 2 hours.

8. The preparation method according to claim 6, characterized in that, In step one, the preparation process of the insulating material includes the following steps: dissolving phytic acid and organomontmorillonite in ethanol at a mass ratio of 1:2, ultrasonically dispersing for 30 minutes, and then drying at 80°C to obtain phytic acid-montmorillonite composite particles; and mixing 90wt%~92wt% flame-retardant ceramicized polyolefin, 5wt%~7wt% phytic acid-montmorillonite composite particles, and 2wt%~3wt% antioxidant 1010 to obtain the insulating material.

9. The preparation method according to claim 6, characterized in that, In step three, the preparation process of the phytic acid synergistic ceramicized composite tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant is added, and the mixture is stirred at high temperature for 20 minutes to obtain the phytic acid-magnesium hydroxide synergist; using the ceramicized composite tape as the substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating-drying integrated process, with a single-sided coating thickness of 0.02mm~0.08mm, pre-baking at 80℃ for 10 minutes in the first stage, and curing at 110℃ for 20 minutes in the second stage.

10. The preparation method according to claim 6, characterized in that, In step three, the preparation process of the phytic acid modified glass fiber tape is as follows: phytic acid and magnesium hydroxide are mixed at a mass ratio of 1:3, 0.5wt% dispersant is added, and the mixture is stirred at high temperature for 20 minutes to obtain a phytic acid-magnesium hydroxide synergist; using alkali-free glass fiber tape as the substrate, the phytic acid-magnesium hydroxide synergist is coated on its surface using a roller coating process, with a single-sided coating thickness of 0.02mm~0.08mm, and dried at 100℃ for 15 minutes.

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