Flexible A-level non-combustible mineral insulated cable and preparation method thereof
By combining low-calorific-value modified mica tape and glass fiber filled rope, the problem of insufficient flexibility and fire resistance of mineral-insulated cables is solved, enabling stable operation in high fire safety locations and meeting the Class A non-combustible standard.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-07
AI Technical Summary
Existing mineral-insulated cables are inadequate in terms of flexibility, ease of installation, fire resistance, and structural stability, and cannot meet the requirements of high fire safety locations. In particular, they are prone to loosening under high temperatures and mechanical vibrations, and cannot meet the Class A non-combustible standard.
The design employs a combination of low-calorific-value modified mica tape and glass fiber filler rope. The core is formed by stranding multiple strands of type II copper conductors. Low-calorific-value modified mica tape and flame-retardant modified resin are used in the wrapping layer and filler layer to form a dense barrier film, which improves flexibility and fire resistance.
It significantly improves the flexibility and structural stability of the cable, enabling it to be laid in confined spaces. It also has high fire resistance, preventing structural loosening under high temperatures and mechanical vibrations, meeting Class A non-combustible standards, and is suitable for high fire safety locations.
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Figure CN121812253A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of high-performance cable production, and particularly relates to a flexible A-class non-combustible mineral insulated cable and a preparation method thereof. BACKGROUND
[0002] In the prior art, mineral insulated cables play a crucial role in places with extremely high fire safety requirements such as high-rise buildings, airports, subways, and nuclear power plants. They can ensure the stable operation of core systems such as fire-fighting power supply and emergency communication, improve the fire safety level of the place, reduce fire accident losses, and protect personnel life and property safety. However, the materials and structures of mineral insulated cables on the market currently have some shortcomings.
[0003] In the prior art, although traditional mineral insulated cables such as BTTZ cables have certain fireproof performance and high-temperature resistance, they can maintain power supply capability in extremely high-temperature environments, but they perform poorly in flexibility and installation convenience. The high hardness makes installation and laying difficult, requires extremely high bending radius, and the joint processing technology is complex, which is prone to moisture absorption and causes insulation performance to decrease. Although the flexible fireproof cable using mica tape as the insulation layer has good flexibility and is convenient to adapt to complex wiring environments, its fireproof performance and structural stability are relatively insufficient. In addition, this type of flexible fireproof cable also has the shortcomings of poor fire integrity, carbonization of organic adhesive under sustained high temperature or flame impact, resulting in insulation failure, substandard combustion performance, and the release of heat and toxic smoke during combustion due to the presence of organic components, which cannot meet the A-class non-combustible standard, and the internal structure is loose under high temperature and mechanical vibration.
[0004] Therefore, in order to comprehensively improve the flexibility, A-class non-combustibility, fire integrity under high temperature, and structural stability of mineral insulated cables, improvements are urgently needed to improve the installation convenience and operation reliability of the cable in fire scenarios. SUMMARY
[0005] In order to solve the technical problems of poor flexibility, difficult installation and laying, high bending radius requirement, complex joint processing technology, and easy moisture absorption leading to decreased insulation performance of traditional mineral insulated cables in the prior art, the insufficient fireproof performance and structural stability, poor fire integrity, and substandard combustion performance of flexible fireproof cables using conventional mica tape wrapping, and the inability to meet the A-class non-combustible standard, the application proposes a flexible A-class non-combustible mineral insulated cable.
[0006] In order to solve the technical problems proposed in the application, the application also provides a preparation method of a flexible A-class non-combustible mineral insulated cable.
[0007] The application adopts the following scheme: a flexible A-class non-combustible mineral insulated cable, comprising a core, a first wrapping layer wrapped outside the core, a filling layer filled between the core and the first wrapping layer, and a sheath layer wrapped outside the first wrapping layer, the core is twisted by a plurality of conductors, each of the conductors is wrapped with a second wrapping layer, the material of the first wrapping layer and the second wrapping layer is selected to be a low-calorific-value modified mica tape, and the material of the conductor is selected to be a second type of copper.
[0008] In some possible embodiments, the filling layer comprises a plurality of filling units filled between the core and the first wrapping layer, the material of the filling unit is selected to be a glass fiber filling rope, and the cross-sectional diameter D, unit length mass G and breaking strength Q of the glass fiber filling rope satisfy the following relationships: 2mm≤D≤9.5mm, 4.5g / m≤G≤30g / m, and 300N≤Q≤1000N.
[0009] In some possible embodiments, the oxygen index O of the glass fiber filling rope satisfies the following relationship: 55%≤O≤65%.
[0010] In some possible embodiments, the preparation method of the low-calorific-value modified mica tape comprises the following steps:
[0011] Step 101. Introduce the connecting substrate into a coating machine, immerse the connecting substrate into a fire-retardant modified resin glue solution at a coating speed of 5 m / min, and obtain a modified connecting substrate after complete immersion;
[0012] In the formula, the mass ratio of the connecting substrate to the fire-retardant modified resin glue solution is 10:3-4.
[0013] Step 102. Transfer the modified connecting substrate prepared in step 101 to a pressing platform, and press the mica onto the surface of the connecting substrate under the conditions of room temperature and 0.3 MPa-0.5 MPa, to obtain a crude composite substrate.
[0014] Step 103. Transfer the crude composite substrate prepared in step 102 to a coating machine, and coat the fire-retardant modified resin glue solution onto the surface of the crude composite substrate under the conditions of room temperature, a coating speed of 5 m / min, and a coating amount of 15 g / m2-20 g / m2, to obtain a fire-retardant composite substrate after coating.
[0015] Step 104. Transfer the fire-retardant composite substrate prepared in step 103 to a drying furnace, and dry the fire-retardant composite substrate under the conditions of a conveying speed of 5 m / min and a drying temperature of 70°C-140°C until the water content of the fire-retardant composite substrate is reduced to 0.5%, and then sequentially go through winding, cutting, packaging, and packaging, to obtain a low-calorific-value modified mica tape product.
[0016] In some possible embodiments, the fire-retardant modified resin glue liquid is composed of the following components in parts by weight: 50-60 parts of silicone resin, 31-36 parts of fire-retardant modifier, 3-6 parts of silicone resin microspheres, 1-2 parts of silicone oil, and 10-15 parts of solvent; wherein the fire-retardant modifier is subjected to surface modification treatment.
[0017] The preparation method of the fire-retardant modified resin glue liquid comprises the following steps: sequentially adding the silicone resin, the fire-retardant modifier, the silicone resin microspheres, the silicone oil, and the solvent into a magnetic stirring kettle according to preset mass proportions, and stirring at room temperature and at 800-1000 rpm for 2-3 hours to obtain the fire-retardant modified resin glue liquid.
[0018] In some possible embodiments, the fire-retardant modifier is composed of the following components in parts by weight based on the total mass of the fire-retardant modifier: 20-25 parts of ultra-fine aluminum hydroxide, 10-15 parts of magnesium hydroxide particles, 2-3 parts of melamine cyanurate, and 1-2 parts of fumed silica.
[0019] In actual implementation, the particle size of the magnesium hydroxide particles is 50-88 μm.
[0020] Further, the median particle size of the magnesium hydroxide particles is 67 μm.
[0021] In some possible embodiments, the preparation method of the ultra-fine aluminum hydroxide comprises the following steps:
[0022] Step 201. Ammonia water with a concentration of 2 mol / L is added drop by drop into an aluminum sulfate solution with a concentration of 1.5 mol / L, and the ammonia water addition is completed when the pH of the system is 7.5-8.0; after the ammonia water addition is completed, the first sol is obtained by reacting at 50°C in a water bath and at 1200 rpm for 2-5 hours.
[0023] Step 202. The first sol in step 201 is transferred to a high-pressure hydrothermal reaction kettle, and the second sol is obtained by reacting at 0.3-0.5 MPa and at 1000 rpm for 4-6 hours; the second sol is subjected to filtration, washing, vacuum drying, and airflow crushing in sequence to obtain the ultra-fine aluminum hydroxide product.
[0024] In some possible embodiments, the particle size R and the specific surface area B of the ultra-fine aluminum hydroxide satisfy the following relationships: 0.5 μm≤R≤2.5 μm and 25 m2 / g≤B≤40 m2 / g.
[0025] In some possible embodiments, the particle size X of the magnesium hydroxide particles satisfies the following relationship: 20 μm≤X≤50 μm.
[0026] In some feasible embodiments, the surface modification treatment of the flame retardant modifier includes the following steps: the flame retardant modifier, anhydrous ethanol, deionized water and silane coupling agent KH-560 are added to a high-speed disperser in a mass ratio of 1:7:1:0.3, dispersed in a water bath at 70°C and 1800 rpm for 1.5-3 hours, and then filtered, washed and dried to obtain the surface-modified flame retardant modifier.
[0027] The specific surface area of the surface-modified flame retardant modifier is 10 m² / g-18 m² / g.
[0028] To address the technical problems raised in this application, this application also provides a method for preparing a flexible Class A non-combustible mineral-insulated cable, which includes the following steps:
[0029] Step 301. The conductor is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 25%-30%, a wrapping tension of 8N-12N, and a wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form a second wrapping layer. After the wrapping is completed, the wire core unit is obtained.
[0030] Step 302. Transfer several individual wire cores to a stranding machine and strand them into wire cores under the conditions that the stranding pitch is 16 to 20 times the outer diameter of the cable and the cable forming speed is 4 m / min. During the stranding process, filler units are filled into the gaps between the individual wire cores. After filling is completed, the filled wire core is obtained.
[0031] Step 303. The filled wire core prepared in step 302 is introduced into the wrapping equipment. Under the conditions of wrapping overlap rate of 25%-30%, wrapping tension of 10N-15N, and wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form the first wrapping layer. After the wrapping is completed, the coarse cable is obtained.
[0032] Step 304. The coarse cable prepared in step 303 is introduced into the longitudinal wrapping equipment. Under the condition that the longitudinal wrapping overlap is 5mm-8mm, a copper strip with a thickness of 0.6mm-0.8mm is longitudinally wrapped around the outer periphery of the coarse cable. After the wrapping is completed, it is sealed by argon arc welding to obtain a flexible Class A non-combustible mineral insulated cable.
[0033] Compared with the prior art, this application has the following beneficial effects:
[0034] This application provides a flexible Class A non-combustible mineral-insulated cable and its manufacturing method. The cable includes a conductor, a first wrapping layer covering the outer periphery of the conductor, a filler layer filling the space between the conductor and the first wrapping layer, and a sheath layer covering the outer periphery of the first wrapping layer. The conductor is composed of multiple strands of Class II copper conductors twisted together, with each conductor wrapped in a second wrapping layer. Both the first and second wrapping layers are made of low-calorific-value modified mica tape. Through the combination of the multi-strand Class II copper conductor twisting design, the low-calorific-value modified mica tape, and the filler layer, the cable's flexibility is significantly improved, meeting the requirements for cable laying in confined spaces. It also effectively enhances the cable's structural stability and fire resistance, preventing structural loosening under high temperatures and mechanical vibration. It features a reasonable design, strong adaptability, controllable implementation costs, and wide applicability to locations with high fire safety requirements, demonstrating significant practical value and ease of promotion and implementation. Attached Figure Description
[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of a flexible Class A non-combustible mineral-insulated cable. Detailed Implementation
[0036] Combination Figure 1 The content shown further illustrates the technical solution proposed in this application. This application adopts the following technical solution: a flexible Class A non-combustible mineral-insulated cable, comprising a conductor 1, a first wrapping layer 2 covering the outer periphery of the conductor 1, a filling layer 3 filling the space between the conductor 1 and the first wrapping layer 2, and a sheath layer 4 covering the outer periphery of the first wrapping layer 2. The conductor 1 is formed by stranding multiple conductors 10, and each conductor 10 is wrapped with a second wrapping layer 11. Both the first wrapping layer 2 and the second wrapping layer 11 are made of low-calorific-value modified mica tape, and the conductors 10 are made of Class II copper.
[0037] In actual implementation, the first wrapping layer has 5 wrapping layers, and the second wrapping layer has 4 wrapping layers.
[0038] In this embodiment, the filling layer 3 includes a plurality of filling units 30 filling the space between the wire core 1 and the first wrapping layer 2. The filling unit 30 is made of glass fiber filling rope, and the cross-sectional diameter D, mass per unit length G, and breaking strength Q of the glass fiber filling rope satisfy the following relationship:
[0039] 2mm≤D≤9.5mm, 4.5g / m≤G≤30g / m, 300N≤Q≤1000N.
[0040] In this embodiment, the oxygen index O of the glass fiber filled rope satisfies the following relationship: 55%≤O≤65%.
[0041] In actual implementation, the average cross-sectional diameter D of the glass fiber filled rope is 3.5 mm, the average mass per unit length G is 7.1 g / m, the average breaking strength Q is 488 N, and the average oxygen index O is 61%. Example 1
[0042] (1) The preparation method of low-calorific-value modified mica tape (first cladding layer / second cladding layer) includes the following steps:
[0043] Step 101. The bonding substrate is introduced into the coating machine and the bonding substrate is immersed in the flame-retardant modified resin liquid at a coating speed of 5 m / min. After complete immersion, the modified bonding substrate is obtained.
[0044] The connecting substrate is made of fiberglass cloth, and the mass ratio of the connecting substrate to the flame-retardant modified resin is 10:3.
[0045] Step 102. Transfer the modified bonding substrate prepared in step 101 to a pressing platform, and press the mica onto the surface of the bonding substrate at room temperature and 0.3 MPa to obtain the rough composite substrate.
[0046] Step 103. Transfer the crude composite substrate prepared in step 102 to a coating machine. Under the conditions of room temperature, coating speed of 5 m / min and coating amount of 15 g / m2, apply flame-retardant modified resin liquid to the surface of the crude composite substrate. After coating, the flame-retardant composite substrate is obtained.
[0047] Step 104. Transfer the flame-retardant composite substrate prepared in step 103 to a drying oven. Dry it at a conveying speed of 5 m / min and a drying temperature of 70°C until the moisture content of the flame-retardant composite substrate is reduced to 0.5%. Then, after winding, cutting, sub-packaging, and packaging, the low-calorific-value modified mica tape is obtained.
[0048] (2) The preparation method of flame-retardant modified resin liquid includes the following steps: according to the components shown in Table 1, add organosilicon resin, flame retardant modifier, silicone resin microspheres, silicone oil and solvent into a magnetic stirring kettle in a predetermined mass ratio, and stir for 2 hours at room temperature and 800 rpm to obtain flame-retardant modified resin liquid.
[0049] (3) The preparation method of ultrafine aluminum hydroxide includes the following steps:
[0050] Step 201. Add 2 mol / L ammonia solution dropwise to a 1.5 mol / L aluminum sulfate solution. When the pH of the system reaches 7.5, the addition of ammonia solution is complete. After the addition of ammonia solution is complete, react for 2 hours in a water bath at 50°C and 1200 rpm to obtain the first sol.
[0051] Step 202. Transfer the first sol from step 201 to a high-pressure hydrothermal reactor and react for 4 hours at 0.3 MPa and 1000 rpm to obtain the second sol. After the second sol is filtered, washed, vacuum dried and air-jet pulverized, the ultrafine aluminum hydroxide product is obtained.
[0052] Among them, the median particle size R of ultrafine aluminum hydroxide was measured to be 0.6 μm, and the median specific surface area B was measured to be 29 m2 / g.
[0053] (4) The surface modification treatment of the flame retardant modifier includes the following steps: the flame retardant modifier, anhydrous ethanol, deionized water, and silane coupling agent KH-560 are added sequentially into a high-speed disperser at a mass ratio of 1:7:1:0.3, dispersed for 1.5 hours under water bath conditions of 70℃ and 1800rpm, and then filtered, washed, and dried sequentially to obtain the surface-modified flame retardant modifier. The average specific surface area of the surface-modified flame retardant modifier is 12m2 / g.
[0054] (5) A method for preparing a flexible Class A non-combustible mineral-insulated cable, comprising the following steps:
[0055] Step 301. The conductor is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 25%, a wrapping tension of 8N, and a wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form a second wrapping layer. After the wrapping is completed, the wire core unit is obtained.
[0056] Step 302. Transfer several individual wire cores to a stranding machine and strand them into wire cores under the conditions that the stranding pitch is 16 times the outer diameter of the cable and the cable forming speed is 4m / min. During the stranding process, filler units are filled into the gaps between the individual wire cores. After filling is completed, the filled wire core is obtained.
[0057] Step 303. The filled wire core prepared in step 302 is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 25%, a wrapping tension of 10N, and a wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form the first wrapping layer. After the wrapping is completed, the coarse cable is obtained.
[0058] Step 304. The coarse cable prepared in step 303 is introduced into the longitudinal wrapping equipment. Under the condition of a longitudinal wrapping overlap of 5mm, a copper strip with a thickness of 0.6mm is longitudinally wrapped around the outer periphery of the coarse cable. After the wrapping is completed, it is sealed by argon arc welding to obtain a flexible Class A non-combustible mineral insulated cable. Example 2
[0059] (1) The preparation method of low-calorific-value modified mica tape (first cladding layer / second cladding layer) includes the following steps:
[0060] Step 101. The bonding substrate is introduced into the coating machine and the bonding substrate is immersed in the flame-retardant modified resin liquid at a coating speed of 5 m / min. After complete immersion, the modified bonding substrate is obtained.
[0061] The connecting substrate is made of fiberglass cloth, and the mass ratio of the connecting substrate to the flame-retardant modified resin is 10:3.5.
[0062] Step 102. Transfer the modified bonding substrate prepared in step 101 to a pressing platform, and press the mica onto the surface of the bonding substrate at room temperature and 0.4 MPa to obtain the rough composite substrate.
[0063] Step 103. Transfer the rough composite substrate prepared in step 102 to a coating machine. Under the conditions of room temperature, coating speed of 5 m / min and coating amount of 16 g / m2, apply flame retardant modified resin liquid to the surface of the rough composite substrate. After coating, the flame retardant composite substrate is obtained.
[0064] Step 104. Transfer the flame-retardant composite substrate prepared in step 103 to a drying oven. Dry it at a conveying speed of 5 m / min and a drying temperature of 80°C until the moisture content of the flame-retardant composite substrate is reduced to 0.5%. Then, after winding, cutting, sub-packaging, and packaging, the low-calorific-value modified mica tape is obtained.
[0065] (2) The preparation method of flame-retardant modified resin liquid includes the following steps: according to the components shown in Table 1, add organosilicon resin, flame retardant modifier, silicone resin microspheres, silicone oil and solvent into a magnetic stirring tank in a predetermined mass ratio, and stir for 2.5 hours at room temperature and 900 rpm to obtain flame-retardant modified resin liquid.
[0066] (3) The preparation method of ultrafine aluminum hydroxide includes the following steps:
[0067] Step 201. Add 2 mol / L ammonia solution dropwise to a 1.5 mol / L aluminum sulfate solution. When the pH of the system reaches 8.0, the addition of ammonia solution is complete. After the addition of ammonia solution is complete, react for 4 hours in a water bath at 50°C and 1200 rpm to obtain the first sol.
[0068] Step 202. Transfer the first sol from step 201 to a high-pressure hydrothermal reactor and react for 5 hours at 0.4 MPa and 1000 rpm to obtain the second sol. After the second sol is filtered, washed, vacuum dried and pulverized by air jet, the ultrafine aluminum hydroxide product is obtained.
[0069] The median particle size R of the ultrafine aluminum hydroxide is 1.1 μm, and the median specific surface area B is 29 m² / g.
[0070] (4) The surface modification treatment of the flame retardant modifier includes the following steps: the flame retardant modifier, anhydrous ethanol, deionized water, and silane coupling agent KH-560 are added sequentially into a high-speed disperser at a mass ratio of 1:7:1:0.3. After dispersion for 2 hours at 70℃ and 1800rpm in a water bath, the mixture is then filtered, washed, and dried to obtain the surface-modified flame retardant modifier. The specific surface area of the surface-modified flame retardant modifier is 13m² / g.
[0071] (5) A method for preparing a flexible Class A non-combustible mineral-insulated cable, comprising the following steps:
[0072] Step 301. The conductor is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 27%, a wrapping tension of 10N, and a wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form a second wrapping layer. After the wrapping is completed, the wire core unit is obtained.
[0073] Step 302. Transfer several individual wire cores to a stranding machine and strand them into wire cores under the conditions that the stranding pitch is 20 times the outer diameter of the cable and the cable forming speed is 4m / min. During the stranding process, filler units are filled into the gaps between the individual wire cores. After filling is completed, the filled wire core is obtained.
[0074] Step 303. The filled wire core prepared in step 302 is introduced into the wrapping equipment. Under the conditions of wrapping overlap rate of 27%, wrapping tension of 12N and wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form the first wrapping layer. After the wrapping is completed, the coarse cable is obtained.
[0075] Step 304. The coarse cable prepared in step 303 is introduced into the longitudinal wrapping equipment. Under the condition of longitudinal wrapping overlap of 8mm, a copper strip with a thickness of 0.7mm is longitudinally wrapped around the outer periphery of the coarse cable. After wrapping, it is sealed by argon arc welding to obtain a flexible Class A non-combustible mineral insulated cable. Example 3
[0076] (1) The preparation method of low-calorific-value modified mica tape (first cladding layer / second cladding layer) includes the following steps:
[0077] Step 101. The bonding substrate is introduced into the coating machine and the bonding substrate is immersed in the flame-retardant modified resin liquid at a coating speed of 5 m / min. After complete immersion, the modified bonding substrate is obtained.
[0078] The connecting substrate is made of fiberglass cloth, and the mass ratio of the connecting substrate to the flame-retardant modified resin is 10:4.
[0079] Step 102. Transfer the modified bonding substrate prepared in step 101 to a pressing platform, and press the mica onto the surface of the bonding substrate at room temperature and 0.5 MPa to obtain the rough composite substrate.
[0080] Step 103. Transfer the rough composite substrate prepared in step 102 to a coating machine. Under the conditions of room temperature, coating speed of 5 m / min and coating amount of 20 g / m2, apply flame-retardant modified resin liquid to the surface of the rough composite substrate. After coating, the flame-retardant composite substrate is obtained.
[0081] Step 104. Transfer the flame-retardant composite substrate prepared in step 103 to a drying oven. Dry it at a conveying speed of 5 m / min and a drying temperature of 140°C until the moisture content of the flame-retardant composite substrate is reduced to 0.5%. Then, after winding, cutting, sub-packaging, and packaging, the low-calorific-value modified mica tape is obtained.
[0082] (2) The preparation method of flame-retardant modified resin liquid includes the following steps: according to the components shown in Table 1, add organosilicon resin, flame retardant modifier, silicone resin microspheres, silicone oil and solvent into a magnetic stirring tank in a predetermined mass ratio, and stir for 3 hours at room temperature and 1000 rpm to obtain flame-retardant modified resin liquid.
[0083] (3) The preparation method of ultrafine aluminum hydroxide includes the following steps:
[0084] Step 201. Add 2 mol / L ammonia solution dropwise to a 1.5 mol / L aluminum sulfate solution. When the pH of the system reaches 8.0, the addition of ammonia solution is complete. After the addition of ammonia solution is complete, react for 5 hours in a water bath at 50°C and 1200 rpm to obtain the first sol.
[0085] Step 202. Transfer the first sol from step 201 to a high-pressure hydrothermal reactor and react for 6 hours at 0.5 MPa and 1000 rpm to obtain the second sol. After the second sol is filtered, washed, vacuum dried and pulverized by air jet, the ultrafine aluminum hydroxide product is obtained.
[0086] The median particle size R of the ultrafine aluminum hydroxide is 2.1 μm, and the median specific surface area B is 29 m² / g.
[0087] (4) The surface modification treatment of the flame retardant modifier includes the following steps: the flame retardant modifier, anhydrous ethanol, deionized water, and silane coupling agent KH-560 are added sequentially into a high-speed disperser at a mass ratio of 1:7:1:0.3. After dispersion for 3 hours at 70℃ and 1800rpm in a water bath, the mixture is then filtered, washed, and dried to obtain the surface-modified flame retardant modifier. The specific surface area of the surface-modified flame retardant modifier is 10m² / g-18m² / g.
[0088] (5) A method for preparing a flexible Class A non-combustible mineral-insulated cable, comprising the following steps:
[0089] Step 301. The conductor is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 30%, a wrapping tension of 12N, and a wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form a second wrapping layer. After the wrapping is completed, the wire core unit is obtained.
[0090] Step 302. Transfer several individual wire cores to a stranding machine and strand them into wire cores under the conditions that the stranding pitch is 20 times the outer diameter of the cable and the cable forming speed is 4m / min. During the stranding process, filler units are filled into the gaps between the individual wire cores. After filling is completed, the filled wire core is obtained.
[0091] Step 303. The filled wire core prepared in step 302 is introduced into the wrapping equipment. Under the conditions of wrapping overlap rate of 30%, wrapping tension of 15N and wrapping speed of 5m / min, the low heat value modified mica tape is wrapped around the outer periphery of the wire core to form the first wrapping layer. After the wrapping is completed, the coarse cable is obtained.
[0092] Step 304. The coarse cable prepared in step 303 is introduced into the longitudinal wrapping equipment. Under the condition of longitudinal wrapping overlap of 8mm, a copper strip with a thickness of 0.8mm is longitudinally wrapped around the outer periphery of the coarse cable. After wrapping, it is sealed by argon arc welding to obtain a flexible Class A non-combustible mineral insulated cable.
[0093] Comparative Example 1
[0094] The difference between Comparative Example 1 and Example 2 is that the flame retardant modifier in the flame retardant modified resin liquid was removed and supplemented with the remaining components, while the other process components remained unchanged.
[0095] Comparative Example 2
[0096] The difference between Comparative Example 2 and Example 2 is that the ultrafine aluminum hydroxide in the flame retardant modifier was removed and supplemented with the remaining components, while the other process components remained unchanged.
[0097] Comparative Example 3
[0098] The difference between Comparative Example 3 and Example 2 is that the surface modification process with flame retardant modifier was removed, while the other process components remained unchanged.
[0099] Comparative Example 4
[0100] Commercially available mineral-insulated cable (BTTZ cable) with the same dimensions and specifications as Comparative Example 2.
[0101] Table 1. Composition of flame-retardant modified resin adhesives in Examples 1-3 and Comparative Examples 1-3
[0102]
[0103] The insulated cables obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to the following tests:
[0104] Test 1: Performed according to JG / T313-2014 "Metal-sheathed Inorganic Mineral Insulated Cables and Terminals with Rated Voltage of 0.6 / 1kV and Below" standard; Select a test piece with a length of 1m and a cross-sectional area of 16mm2, and repeatedly bend it 3 times at a speed of 5rad / min at room temperature (2 times in the forward direction and 1 time in the reverse direction). After bending, observe whether the metal sheath is cracked and whether the insulation layer is damaged. Test the maximum bending radius of the cable test piece to evaluate the cable flexibility.
[0105] Test 2: Performed according to JG / T313-2014 standard; Take test pieces 1-5 after bending in Test 1, dissect them along the axis, observe whether the wrapping insulation layer and wrapping tape layer are loose or displaced, whether the glass fiber filling rope is detached, and whether the metal sheath is deformed, and judge the structural stability of the cable under mechanical action.
[0106] Test 3: Performed according to JG / T313-2014 standard; Select a test piece with a length of 1.5m and a cross-sectional area of 16mm2 and a matching terminal, connect it to the rated current circuit and place it in a fire resistance test furnace, raise the temperature to 950℃ at a heating rate of 5℃ / min and continue for 180min, during which time monitor whether the circuit is short-circuited and whether the power supply is interrupted, and judge the fire resistance performance of the cable.
[0107] Test 4: Performed according to GB 31247-2014 "Classification of Combustion Performance of Cables and Optical Fibers" standard; select a test specimen with a length of 1.5m and a cross-sectional area of 16mm2, conduct non-combustibility test, measure oxygen index, smoke density (≤50), and total heat release value (≤2MJ / kg) during combustion, observe whether molten droplets and toxic fumes are produced, and determine whether it meets the Class A combustion standard. The test results are shown in Table 2 below.
[0108] Table 2 Results of Tests 1-4
[0109]
[0110] As shown in Table 2, Examples 1-3 provide a flexible Class A non-combustible mineral-insulated cable, which includes a conductor, a first wrapping layer covering the outer periphery of the conductor, a filler layer filling the space between the conductor and the first wrapping layer, and a sheath layer covering the outer periphery of the first wrapping layer. The conductor is made of multiple strands of Class II copper conductors (Class II copper as specified in GB / T 5231-2012) twisted together, and each conductor is wrapped with a second wrapping layer. Both the first and second wrapping layers are made of low-calorific-value modified mica tape. The low-calorific-value modified mica tape is prepared by first coating a flame-retardant modified resin solution onto the surface of glass fiber cloth, and then pressing mica paper onto the surface of the glass fiber cloth. In the flame-retardant modified resin solution, polymethylvinylsiloxane provides matrix adhesion and a high-temperature resistant skeleton. Polymethylsiloxane fills the gaps between long chains, adjusting the viscosity of the resin system through differences in molecular chain length, and avoiding excessive shrinkage after curing. Polymethylvinylsiloxane contains unsaturated vinyl groups, which can undergo cross-linking reactions with the epoxy groups on the surface of the surface-modified flame retardant modifier to form a three-dimensional network structure; this improves the uniformity of cross-linking, thereby providing a highly flexible and stable support skeleton for the glass fiber cloth.
[0111] By adding ultrafine aluminum hydroxide and magnesium hydroxide particles to the flame-retardant modified resin, they can decompose endothermically under high temperature conditions. On the one hand, this dissipates the heat of combustion and lowers the system temperature; on the other hand, the Al2O3 and MgO nanoparticles generated by the decomposition form a dense barrier film on the surface of the glass fiber cloth, further isolating oxygen and combustible gases.
[0112] After surface modification, the specific surface area of ultrafine aluminum hydroxide and magnesium hydroxide particles is significantly increased. On the one hand, they can fully contact the resin skeleton, significantly improving its dispersion performance and increasing the connection sites between the ultrafine aluminum hydroxide and magnesium hydroxide particles and the resin skeleton. On the other hand, they crosslink with the resin skeleton through the -Si-O- bonds on their surface, further improving the connection stability between the ultrafine aluminum hydroxide and magnesium hydroxide particles and the resin skeleton, thereby improving the density of the nano-Al2O3 and MgO barrier film generated under high temperature conditions, and thus improving the fire resistance of the cable.
[0113] By using fiberglass cloth as the connecting substrate and flame-retardant modified resin as the connecting material, flame-retardant units can be effectively filled and arranged on the surface of the fiberglass cloth. This not only effectively ensures the flexibility of the cable, but also forms a dense barrier film on the fiberglass cloth under high temperature conditions, effectively balancing the cable's flexibility and fire resistance requirements.
[0114] In Comparative Example 1, the flame retardant modifier was removed. Firstly, under high-temperature conditions, the resin matrix is prone to breakage, failing to form a dense Al2O3 and MgO barrier film on the fiberglass cloth surface. This prevents heat dissipation during combustion, significantly reducing fire resistance (total heat release value 2.8 MJ / kg, exceeding Class A standard). Furthermore, the toxic fumes are not neutralized by melamine cyanurate. Secondly, the resin-substrate interface relies solely on van der Waals forces (without the -Si-O- bonds on the flame retardant surface), resulting in weak bonding. The fiberglass cloth's flexibility is significantly reduced, consequently leading to a significant decrease in cable flexibility (bending radius 180 mm), making it completely unsuitable for high-safety applications.
[0115] In Comparative Example 2, fine aluminum hydroxide was removed, and the resin matrix lacked ultrafine particles for guidance. Larger magnesium hydroxide particles were easily dispersed unevenly, resulting in a narrow decomposition endothermic range at high temperatures, poor gap-filling effect of the barrier film, insufficient density, and significantly reduced fire resistance (continuous power supply for 153 min, total heat release value 1.9 MJ / kg).
[0116] In Comparative Example 3, the surface modification process that removed the flame retardant modifier resulted in an unmodified flame retardant surface rich in -OH bonds, which has poor compatibility with the resin matrix, is prone to agglomeration, and easily forms stress concentration points within the resin matrix. During bending, cracks preferentially propagate. At high temperatures, the agglomerates separate from the resin interface, forming thermal channels, accelerating insulation failure, and thus significantly reducing the flexibility and fire resistance of the cable.
[0117] Comparative Example 4 is a commercially available BTTZ cable, which is filled with inorganic insulating powder. The cable has poor flexibility (bending radius of 250mm), poor structural stability (the inorganic insulating powder inside is easy to loosen, which in turn causes the copper conductor to deform), gaps between the inorganic insulating powder inside, limited flame retardant performance, and cannot form a dense insulating film on the outer periphery of the copper conductor under high temperature conditions. It also has poor fire resistance (continuous power supply for 118 minutes, rapid insulation failure, total heat release value of 3.1MJ / kg), and cannot meet the usage requirements of narrow spaces and high-safety scenarios.
[0118] This application provides a flexible Class A non-combustible mineral-insulated cable and its manufacturing method. The cable includes a conductor, a first wrapping layer covering the outer periphery of the conductor, a filler layer filling the space between the conductor and the first wrapping layer, and a sheath layer covering the outer periphery of the first wrapping layer. The conductor is composed of multiple strands of Class II copper conductors twisted together, with each conductor wrapped in a second wrapping layer. Both the first and second wrapping layers are made of low-calorific-value modified mica tape. Through the combination of the multi-strand Class II copper conductor twisting design, the low-calorific-value modified mica tape, and the filler layer, the cable's flexibility is significantly improved, meeting the requirements for cable laying in confined spaces. It also effectively enhances the cable's structural stability and fire resistance, preventing structural loosening under high temperatures and mechanical vibration. It features a reasonable design, strong adaptability, controllable implementation costs, and wide applicability to locations with high fire safety requirements, demonstrating significant practical value and ease of promotion and implementation.
[0119] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A flexible Class A non-combustible mineral-insulated cable, characterized in that, The device includes a wire core (1), a first wrapping layer (2) covering the outer periphery of the wire core (1), a filler layer (3) filling the space between the wire core (1) and the first wrapping layer (2), and a sheath layer (4) covering the outer periphery of the first wrapping layer (2). The wire core (1) is made of multiple strands of conductor (10) twisted together. Each conductor (10) is wrapped with a second wrapping layer (11). The first wrapping layer (2) and the second wrapping layer (11) are both made of low-heat-value modified mica tape. The conductor (10) is made of second-class copper.
2. The flexible Class A non-combustible mineral-insulated cable according to claim 1, characterized in that, The filling layer (3) includes a plurality of filling units (30) filled between the wire core (1) and the first wrapping layer (2). The filling unit (30) is made of glass fiber filling rope. The cross-sectional diameter D, unit length mass G and breaking strength Q of the glass fiber filling rope satisfy the following relationship: 2mm≤D≤9.5mm, 4.5g / m≤G≤30g / m, 300N≤Q≤1000N.
3. A flexible Class A non-combustible mineral-insulated cable according to claim 2, characterized in that, The oxygen index (O) of the glass fiber filled rope satisfies the following relationship: 55% ≤ O ≤ 65%.
4. A flexible Class A non-combustible mineral-insulated cable according to claim 1, characterized in that, The preparation method of the low-calorific-value modified mica tape includes the following steps: Step 101. The bonding substrate is introduced into a coating machine and immersed in flame-retardant modified resin solution at a coating speed of 5 m / min. After complete immersion, the modified bonding substrate is obtained; wherein, the mass ratio of the bonding substrate to the flame-retardant modified resin solution is 10:(3-4); Step 102. The modified bonding substrate obtained in Step 101 is transferred to a pressing platform, and mica is pressed onto the surface of the bonding substrate at room temperature and 0.3 MPa-0.5 MPa to obtain a rough composite substrate; Step 103. The modified bonding substrate obtained in Step 102 is then transferred to a pressing platform, and mica is pressed onto the surface of the bonding substrate at room temperature and 0.3 MPa-0.5 MPa to obtain a rough composite substrate; Step 103. The modified bonding substrate obtained in Step 102 is then transferred to a pressing platform. The crude composite substrate prepared in step 103 is transferred to a coating machine. Under the conditions of room temperature, coating speed of 5 m / min, and coating amount of 15 g / m2-20 g / m2, flame-retardant modified resin is coated on the surface of the crude composite substrate. After coating, the flame-retardant composite substrate is obtained. Step 104. The flame-retardant composite substrate prepared in step 103 is transferred to a drying oven. Under the conditions of conveying speed of 5 m / min and drying temperature of 70℃-140℃, it is dried until the moisture content of the flame-retardant composite substrate is reduced to 0.5%. Then, it is sequentially wound, cut, divided and packaged to obtain the low calorific value modified mica tape finished product.
5. A flexible Class A non-combustible mineral-insulated cable according to claim 4, characterized in that, The flame-retardant modified resin solution is composed of the following components by weight: 50-60 parts of organosilicon resin, 31-36 parts of flame-retardant modifier, 3-6 parts of silicone resin microspheres, 1-2 parts of silicone oil, and 10-15 parts of solvent; wherein the flame-retardant modifier undergoes surface modification treatment; the preparation method of the flame-retardant modified resin solution includes the following steps: adding organosilicon resin, flame-retardant modifier, silicone resin microspheres, silicone oil, and solvent sequentially into a magnetic stirring tank according to a preset mass ratio, and stirring for 2-3 hours at room temperature and 800-1000 rpm to obtain the flame-retardant modified resin solution.
6. A flexible Class A non-combustible mineral-insulated cable according to claim 5, characterized in that, Based on the total mass of the flame retardant modifier, the flame retardant modifier is composed of the following components by weight: 20-25 parts of ultrafine aluminum hydroxide, 10-15 parts of magnesium hydroxide microparticles, 2-3 parts of melamine cyanurate, and 1-2 parts of fumed silica.
7. A flexible Class A non-combustible mineral-insulated cable according to claim 6, characterized in that, The preparation method of the ultrafine aluminum hydroxide includes the following steps: Step 201. Ammonia water with a concentration of 2 mol / L is added dropwise to an aluminum sulfate solution with a concentration of 1.5 mol / L. When the pH of the system reaches 7.5-8.0, the addition of ammonia water is completed. After the addition of ammonia water is completed, the mixture is reacted at 50℃ and 1200 rpm in a water bath for 2-5 hours to obtain the first sol. Step 202. The first sol from step 201 is transferred to a high-pressure hydrothermal reactor and reacted at 0.3MPa-0.5MPa and 1000 rpm for 4-6 hours to obtain the second sol. The second sol is then filtered, washed, vacuum dried, and pulverized by air jet milling to obtain the finished ultrafine aluminum hydroxide product.
8. A flexible Class A non-combustible mineral-insulated cable according to claim 6, characterized in that, The particle size R and specific surface area B of the ultrafine aluminum hydroxide satisfy the following relationships: 0.5μm≤R≤2.5μm, 25m2 / g≤B≤40m2 / g.
9. A flexible Class A non-combustible mineral-insulated cable according to claim 5, characterized in that, The surface modification treatment of the flame retardant modifier includes the following steps: the flame retardant modifier, anhydrous ethanol, deionized water and silane coupling agent KH-560 are added to a high-speed disperser in a mass ratio of 1:7:1:0.
3. After dispersing for 1.5h-3h under the conditions of water bath at 70℃ and 1800rpm, the mixture is then filtered, washed and dried to obtain the surface-modified flame retardant modifier.
10. A method for preparing a flexible Class A non-combustible mineral-insulated cable according to any one of claims 1-9, characterized in that, Includes the following steps: Step 301. Introduce the conductor into the wrapping equipment. Under the conditions of a wrapping overlap rate of 25%-30%, a wrapping tension of 8N-12N, and a wrapping speed of 5m / min, wrap the low-calorific-value modified mica tape around the outer circumference of the conductor to form a second wrapping layer. After wrapping, a single conductor unit is obtained. Step 302. Transfer several conductor units to a stranding machine. Under the conditions of a stranding pitch of 16-20 times the cable outer diameter and a cable forming speed of 4m / min, strand them into a conductor. During the stranding process, filler units are filled into the gaps between the conductor units. After filling, a filled conductor unit is obtained. Step 303. In Step 3... The filled wire core prepared in step 02 is introduced into the wrapping equipment. Under the conditions of a wrapping overlap rate of 25%-30%, a wrapping tension of 10N-15N, and a wrapping speed of 5m / min, a low-calorific-value modified mica tape is wrapped around the outer periphery of the wire core to form the first wrapping layer. After the wrapping is completed, a coarse cable is obtained. Step 304. The coarse cable prepared in step 303 is introduced into the longitudinal wrapping equipment. Under the condition of a longitudinal wrapping overlap of 5mm-8mm, a copper tape with a thickness of 0.6mm-0.8mm is longitudinally wrapped around the outer periphery of the coarse cable. After the wrapping is completed, it is sealed by argon arc welding to obtain a flexible Class A non-combustible mineral insulated cable.