B1-level fireproof cable based on polypropylene insulation and production process thereof

Abstract

The invention discloses a B1-level fireproof cable based on polypropylene insulation and a production process thereof. On one hand, the B1-level fireproof cable based on polypropylene insulation comprises an outer sheath and a plurality of inner wire cores, and the outer sheath comprises an ultra-thin corrugated copper sheath layer and a low-smoke outer flame-retardant adhesive layer wrapping the ultra-thin corrugated copper sheath layer; the inner wire core comprises a wire core body, a ceramic adhesive tape layer wrapping the wire core body, and a flame-retardant polypropylene insulating layer wrapping the ceramic adhesive tape layer; a flame-retardant support is arranged in the outer sheath, the plurality of inner wire cores are arranged in the outer sheath along the circumferential direction of the flame-retardant support, and the remaining empty area in the outer sheath is filled with a flame-retardant rope. On the other hand, the invention provides a production process of the B1-level fireproof cable based on polypropylene insulation. The cable is excellent in fireproof and flame-retardant performance, the low-smoke and low-toxicity flame-retardant design is adopted, fire spreading can be effectively delayed during combustion, and the cable is excellent in insulating performance and good in insulating performance at high temperature.

Description

Technical Field

[0001] This application relates to the field of fire-resistant cable technology, and in particular to a B1-grade fire-resistant cable based on polypropylene insulation and its manufacturing process. Background Technology

[0002] With the accelerating pace of urbanization in my country, the use of electrical wires and cables is increasing year by year, leading to increasingly prominent fire hazards. Fires can cause enormous economic losses. For example, fires involving residential cables can result in significant loss of life and property; similarly, fires involving rail transit cables can paralyze transportation, impacting urban residents' travel. Such disasters caused by cable fires are frequently reported globally, driving the upgrading of cable fire-resistant technology. Currently, the technological upgrade goals for high-grade fire-resistant cables mainly focus on the following three aspects: First, ensuring the cable maintains insulation at temperatures up to 850℃; second, employing highly efficient flame-retardant designs to slow the spread of fire; and third, reducing smoke toxicity to extremely low levels.

[0003] Traditional cable fire protection methods include passive fire prevention technologies such as fire-retardant coatings, fire-retardant wrapping tapes, and fire-retardant partitions. Currently, the most widely used cable fire protection technology is a composite fire-retardant insulation structure using full mica tape wrapping (phlogopite or synthetic mica) or mica tape wrapping combined with cross-linked polyethylene. The full mica tape structure suffers from problems such as susceptibility to moisture absorption, insufficient mechanical strength leading to damage, and the mica tape crumbling into powder after burning, losing its insulating function. The composite fire-retardant insulation structure using mica tape and cross-linked polyethylene requires cross-linking to increase the operating temperature of the polyethylene insulation layer, typically using silane cross-linking, ultraviolet irradiation cross-linking, or electron accelerator irradiation cross-linking. Silane cross-linking uses water vapor as the cross-linking medium, which is detrimental to the mica tape; ultraviolet irradiation cross-linking has reported post-cross-linking issues; and electron accelerator irradiation cross-linking involves high investment and cost. Furthermore, the aforementioned widely used fire-retardant cables and most other fire-retardant cables currently on the market fail to meet the technical requirements of the current high-grade fire-retardant cable technology upgrade goals.

[0004] Therefore, designing an insulated fireproof cable that can meet the current technical upgrade goals of high-level fireproof cables is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In order to solve at least one of the above-mentioned technical problems, and to develop an insulated fireproof cable with excellent fire-retardant performance, low smoke and low toxicity flame-retardant design, which can effectively delay the spread of fire during combustion, and excellent insulation performance, with good insulation performance at high temperatures, this application provides a B1-grade fireproof cable based on polypropylene insulation and its manufacturing process.

[0006] On one hand, this application provides a B1-grade fire-resistant cable based on polypropylene insulation, including an outer sheath and multiple inner cores. The outer sheath includes an ultra-thin corrugated copper sheath layer and a low-smoke flame-retardant outer adhesive layer covering the ultra-thin corrugated copper sheath layer. The inner cores include a core body, a ceramic tape layer covering the core body, and a flame-retardant polypropylene insulation layer covering the ceramic tape layer. A flame-retardant support is provided inside the outer sheath, and the multiple inner cores are arranged circumferentially along the flame-retardant support inside the outer sheath. The remaining empty space inside the outer sheath is filled with flame-retardant rope. The mass proportions of each raw material component in the flame-retardant polypropylene insulation layer include: 100 parts PP resin, 14-16 parts nano silica, 10-12 parts maleic anhydride grafted polyolefin elastomer, 36-40 parts magnesium hydroxide, 6-10 parts zinc borate, 0.4-0.6 parts NP-657 nucleating agent, and 0.3-0.5 parts composite antioxidant.

[0007] Optionally, the mass ratio of each raw material component in the low-smoke flame-retardant adhesive layer includes: 40-50 parts of methyl vinyl silicone rubber, 14-20 parts of vinyl silicone oil, 6-10 parts of hydrogen-containing silicone oil, 3-5 parts of Karstedt catalyst, 2-4 parts of pigment, 12-18 parts of terephthalic diisocyanate, 18-24 parts of hydroxylated carbon nanotubes, 30-38 parts of coated ammonium polyphosphate, and 6-10 parts of nano-kaolin.

[0008] Optionally, the mass ratio of each raw material component in the low-smoke flame-retardant adhesive layer includes: 44-46 parts of methyl vinyl silicone rubber, 16-18 parts of vinyl silicone oil, 8-9 parts of hydrogen-containing silicone oil, 4-4.2 parts of Karstedt catalyst, 2-4 parts of pigment, 15-16 parts of terephthalic diisocyanate, 20-22 parts of hydroxylated carbon nanotubes, 34-36 parts of coated ammonium polyphosphate, and 8-8.4 parts of nano-kaolin.

[0009] Optionally, the mass ratio of each raw material component in the ceramic tape layer includes: 20-30 parts of methyl vinyl silicone rubber, 10-20 parts of vinyl silicone oil, 4-8 parts of hydrogen-containing silicone oil, 2-4 parts of Karstedt catalyst, 10-14 parts of high-purity aluminum silicate fiber, 18-22 parts of nano aluminum silicate, 8-12 parts of nano silica, 14-18 parts of magnesium hydroxide, and 6-10 parts of sintering aid.

[0010] Optionally, the mass ratio of each raw material component in the ceramic tape layer includes: 26-28 parts of methyl vinyl silicone rubber, 14-15 parts of vinyl silicone oil, 5-5.5 parts of hydrogen-containing silicone oil, 2.8-3.2 parts of Karstedt catalyst, 12-12.5 parts of high-purity aluminum silicate fiber, 20-20.5 parts of nano aluminum silicate, 10-11 parts of nano silica, 15-16 parts of magnesium hydroxide, and 8-8.5 parts of sintering aid.

[0011] Optionally, the sintering aid is composed of manganese oxide and silicon tetraboride, wherein the mass ratio of manganese oxide to silicon tetraboride is 1~1.5:1.

[0012] Optionally, the thickness of the ultra-thin corrugated copper sheath layer is 0.15~0.3mm.

[0013] Optionally, the flame-retardant support is made of high-purity aluminum silicate fiber column.

[0014] Optionally, a ceramic tape layer is also provided between the low-smoke flame-retardant outer adhesive layer and the ultra-thin corrugated copper sheath layer.

[0015] On the other hand, this application provides a manufacturing process for the aforementioned polypropylene-insulated B1-class fire-resistant cable, including the following steps: S1. Preparation of ceramic tape, flame-retardant polypropylene insulating masterbatch and external flame-retardant adhesive masterbatch; S2. Wrap the ceramic tape prepared in step S1 around the wire core body using a chuck-type adjustable wrapping and wire-wrapping die to form a ceramic tape layer. Then, use a hot extrusion equipment to extrude a flame-retardant polypropylene insulation layer on the outside of the ceramic tape layer using the flame-retardant polypropylene insulation masterbatch prepared in step S1 as raw material to obtain the inner wire core. S3. Arrange the inner core obtained in step S2 along the circumferential direction of the flame-retardant support, place it in the ultra-thin corrugated copper sheath layer, fill the empty area with flame-retardant rope, and then obtain the cable blank. S4. Using the flame-retardant masterbatch prepared in step S1 as raw material, a low-smoke flame-retardant adhesive layer is extruded onto the cable blank using a hot extrusion equipment to obtain a B1-grade fireproof cable based on polypropylene insulation.

[0016] In summary, the present invention has at least one of the following beneficial technical effects: 1. The fireproof cable of this application uses ceramic tape as the outer sheath of the core body, and an outer flame-retardant polypropylene insulation layer to form the inner core. This composite outer sheath not only has excellent flame-retardant properties, but also excellent electrical insulation properties. In addition, the ceramic tape used in this application has excellent flame-retardant and heat-insulating properties, and uses inorganic materials, which have extremely excellent low-smoke flame-retardant properties and do not drip when burning. Under high-temperature combustion conditions, it can form a dense ceramic layer to cover the core body, which can play a role in high-temperature insulation and heat insulation. The flame-retardant polypropylene insulation layer of this application adopts a specific resin system ratio combined with an inorganic flame-retardant system, which has certain high-temperature resistance, excellent low-smoke flame-retardant properties, and excellent electrical insulation properties.

[0017] 2. The fire-resistant cable of this application uses an ultra-thin corrugated copper sheath combined with an external low-smoke flame-retardant adhesive layer as the composite outer sheath of the cable. It also has excellent low-smoke flame-retardant performance and good weather resistance, which can provide good protection for the inner core and further improve the fire-resistant and flame-retardant performance of the cable. The excellent flame-retardant performance allows the use of a thinner corrugated copper sheath, which not only improves the flexibility of the cable but also effectively reduces costs. In addition, the fire-retardant rope filling and flame-retardant support are set inside the composite outer sheath, which can further provide good flame-retardant protection for the inner core, so that the fire-resistant cable of this application can reach the B1 level or above.

[0018] 3. The production process of this application adopts a chuck-type adjustable wrapping and line die wrapping, combined with the overall process design of hot extrusion equipment. The overall process is relatively simple, the equipment is adjustable and versatile, the production efficiency is high, the yield rate is extremely high, and the overall production cost is relatively low. Attached Figure Description

[0019] Figure 1 This is a cross-sectional structural diagram of Embodiment 1 of this application; Figure 2 This is a cross-sectional structural diagram of Embodiment 9 of this application. Detailed Implementation

[0020] The present application will be further described in detail below with reference to the embodiments.

[0021] This application provides a B1-grade fire-resistant cable based on polypropylene insulation, including an outer sheath and multiple inner cores. The outer sheath includes a low-smoke flame-retardant outer adhesive layer 1 and an ultra-thin corrugated copper sheath layer 2 encased within the low-smoke flame-retardant outer adhesive layer 1. The inner cores include a core body 4, a ceramic tape layer 5 covering the core body 4, and a flame-retardant polypropylene insulation layer 6 covering the ceramic tape layer 5. A flame-retardant support 3 is provided inside the outer sheath, and the multiple inner cores are arranged circumferentially along the flame-retardant support 3 inside the outer sheath. The remaining empty space inside the outer sheath is filled with flame-retardant rope. The flame-retardant polypropylene insulation layer 6 comprises the following components in the following mass ratios: 100 parts PP resin, 14-16 parts nano silica, 10-12 parts maleic anhydride grafted polyolefin elastomer, 36-40 parts magnesium hydroxide, 6-10 parts zinc borate, 0.4-0.6 parts NP-657 nucleating agent, and 0.3-0.5 parts composite antioxidant.

[0022] The manufacturing process of the B1-class fire-resistant cable based on polypropylene insulation described in this application includes the following steps: S1. Preparation of ceramic tape, flame-retardant polypropylene insulating masterbatch and external flame-retardant adhesive masterbatch; S2. Wrap the ceramic tape prepared in step S1 around the outside of the wire core body 4 using a chuck-type adjustable wrapping and wire-wrapping die to form a ceramic tape layer 5. Then, use a hot extrusion equipment to extrude a flame-retardant polypropylene insulation layer 6 around the ceramic tape layer 5 using the flame-retardant polypropylene insulation masterbatch prepared in step S1 as raw material to obtain the inner wire core. S3. Arrange the inner core obtained in step S2 along the flame-retardant support 3 in the circumferential direction, place it in the ultra-thin corrugated copper sheath layer 2, fill the empty area with flame-retardant rope, and then obtain the cable blank. S4. Using the flame-retardant masterbatch prepared in step S1 as raw material, a low-smoke flame-retardant layer 1 is extruded onto the cable blank using a hot extrusion device to obtain a B1-grade fireproof cable based on polypropylene insulation.

[0023] Prior to this application, existing fire-resistant cables mostly used a composite sheathing layer formed by mica tape and cross-linked polyethylene to cover the metal core. A corrugated copper sheath was then placed inside, and finally, flame-retardant rope was added. Some fire-resistant cables also had an outer rubber sleeve attached to the corrugated copper sheath to improve weather resistance. Although these types of fire-resistant cables achieved high fire resistance ratings, reaching B1, and had excellent insulation performance at room temperature, in actual fires, the cross-linked polyethylene would melt at high temperatures, causing the internal cores to stick together. Furthermore, the insulation performance of the mica tape would significantly decrease under high temperatures, leading to short circuits and exacerbating the fire.

[0024] The applicant of this application adopted a multi-dimensional design to design the fireproof cable of this application, adding an inner flame-retardant support 3, which can effectively prevent the core from sticking together at high temperatures under the action of the filled flame-retardant rope; in addition, ceramic tape combined with flame-retardant polypropylene insulation layer 6 is used as the composite sheath of the core body, which has excellent insulation performance at room temperature. At high temperature, the inorganic components in the inorganic flame-retardant system of polypropylene and the ceramic components contained in the ceramic tape can be sintered to form a dense ceramic layer, forming a flame-retardant, heat-insulating and insulating ceramic outer layer, which effectively ensures high-temperature electrical insulation; while the outer ultra-thin corrugated copper sheath and low-smoke outer flame-retardant adhesive layer 1 can effectively provide external flame-retardant protection, and the intumescent flame-retardant system of the low-smoke outer flame-retardant adhesive layer 1 can effectively delay the spread of fire.

[0025] The following are preparation examples and embodiments of this application.

[0026] The main raw materials used in the preparation examples and embodiments of this application are all commercially available.

[0027] Among them, polypropylene resin was purchased from Yanshan Petrochemical; nano-silica was purchased from Beijing Deco Island Gold Technology Co., Ltd.; magnesium hydroxide, model SS-MH6PG, D50 particle size 1.0~2.0μm, was purchased from Qinghe County Ruijiang Metal Materials Co., Ltd.; zinc borate was purchased from Shanghai Aladdin; maleic anhydride grafted polyolefin elastomer, POE-g-MAH, model Dow GR216, grafting rate 0.5~1.0%, was purchased from Shanghai Tiansu Trading Co., Ltd.; NP-657 nucleating agent was purchased from Beijing Jihaichuan Technology Development Co., Ltd.; composite antioxidant, BASF B225, was purchased from Nanjing Kexulai Chemical Co., Ltd.; methyl vinyl silicone rubber, 112 raw rubber, was purchased from Guangzhou Shisheng Chemical Co., Ltd.; vinyl silicone oil, 1000CS type, was purchased from Hubei Longsheng Sihai New Materials Co., Ltd.; and hydrogen-containing silicone oil was purchased from Shandong Longhui. Chemical Co., Ltd.; Karstedt catalyst, purchased from Hubei Shineng Chemical Technology Co., Ltd.; terephthalic diisocyanate, 95% purity, purchased from Shanghai Aladdin; hydroxylated carbon nanotubes, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; coated ammonium polyphosphate, phosphorus content approximately 30%, average particle size 5μm, purchased from Shanghai Huanyang Chemical Technology Co., Ltd.; nano-kaolin, particle size 10~100nm, purchased from Qingdao Taiyang Sheng Chemical Co., Ltd.; high-purity aluminosilicate fiber and nano-high-purity aluminosilicate powder, purchased from Zhengzhou Shengshi Jinding Thermal Insulation and Refractory Materials Co., Ltd.; manganese oxide, nano-grade MnO2, purchased from Wuhan Jiyesheng Chemical Co., Ltd.; silicon tetraboride, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; ceramic fireproof silicone tape, purchased from Shanghai Kete New Materials Co., Ltd.; low-smoke flame-retardant silicone rubber masterbatch, purchased from Ningbo Daoruo Organosilicon Co., Ltd.

[0028] The following is a preparation example of this application.

[0029] Preparation Example 1 The mass ratio of each raw material component in the flame-retardant polypropylene insulating masterbatch of this preparation example includes: 100 parts PP resin, 14 parts nano silica, 10 parts maleic anhydride grafted polyolefin elastomer, 36 parts magnesium hydroxide, 6 parts zinc borate, 0.4 parts NP-657 nucleating agent, and 0.3 parts composite antioxidant.

[0030] The preparation of the flame-retardant polypropylene masterbatch in this example adopts the following steps: the raw material components in the formula are mixed evenly, added to a twin-screw extruder, and melt extruded and granulated to obtain the masterbatch; the extrusion granulation process parameters are as follows: zone 1 185℃, zone 2 190℃, zone 3 195℃, zone 4 200℃, zone 5 195℃, zone 6 190℃, and the screw speed is 200 rpm.

[0031] Preparation Example 2 The mass ratio of each raw material component in the flame-retardant polypropylene insulating masterbatch of this preparation example includes: 100 parts PP resin, 16 parts nano silica, 12 parts maleic anhydride grafted polyolefin elastomer, 40 parts magnesium hydroxide, 10 parts zinc borate, 0.6 parts NP-657 nucleating agent, and 0.5 parts composite antioxidant.

[0032] The preparation of the flame-retardant polypropylene masterbatch in this example adopts the following steps: the raw material components in the formula are mixed evenly, added to a twin-screw extruder, and melt extruded and granulated to obtain the masterbatch; the extrusion granulation process parameters are as follows: zone 1 185℃, zone 2 190℃, zone 3 195℃, zone 4 200℃, zone 5 195℃, zone 6 190℃, and the screw speed is 200 rpm.

[0033] Preparation Example 3 The mass ratio of each raw material component in the flame-retardant polypropylene insulating masterbatch of this preparation example includes: 100 parts PP resin, 15 parts nano silica, 10.8 parts maleic anhydride grafted polyolefin elastomer, 38 parts magnesium hydroxide, 8 parts zinc borate, 0.5 parts NP-657 nucleating agent, and 0.4 parts composite antioxidant.

[0034] The preparation of the flame-retardant polypropylene masterbatch in this example adopts the following steps: the raw material components in the formula are mixed evenly, added to a twin-screw extruder, and melt extruded and granulated to obtain the masterbatch; the extrusion granulation process parameters are as follows: zone 1 185℃, zone 2 190℃, zone 3 195℃, zone 4 200℃, zone 5 195℃, zone 6 190℃, and the screw speed is 200 rpm.

[0035] Preparation Example 4 The mass proportions of the raw material components in the ceramic tape of this preparation example include: 30 parts methyl vinyl silicone rubber, 20 parts vinyl silicone oil, 8 parts hydrogen-containing silicone oil, 4 parts Karstedt catalyst, 14 parts high-purity aluminum silicate fiber, 22 parts nano aluminum silicate, 12 parts nano silica, 18 parts magnesium hydroxide, and 10 parts sintering aid (manganese dioxide and silicon tetraboride in a mass ratio of 1.5:1).

[0036] The ceramic tape prepared in this example is prepared by the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes. After casting, rolling and cutting, a 0.3mm thick ceramic tape is made.

[0037] Preparation Example 5 The mass proportions of each raw material component in the ceramic tape of this preparation example include: 20 parts methyl vinyl silicone rubber, 10 parts vinyl silicone oil, 4 parts hydrogen-containing silicone oil, 2 parts Karstedt catalyst, 10 parts high-purity aluminum silicate fiber, 18 parts nano aluminum silicate, 8 parts nano silica, 14 parts magnesium hydroxide, and 6 parts sintering aid (manganese dioxide and silicon tetraboride in a mass ratio of 1.5:1).

[0038] The ceramic tape prepared in this example is prepared by the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes. After casting, rolling and cutting, a 0.3mm thick ceramic tape is made.

[0039] Preparation Example 6 The ceramic tape of this preparation example has the following raw material components in the following mass proportions: 26 parts methyl vinyl silicone rubber, 14 parts vinyl silicone oil, 5 parts hydrogen-containing silicone oil, 2.8 parts Karstedt catalyst, 12 parts high-purity aluminum silicate fiber, 20 parts nano aluminum silicate, 10 parts nano silica, 15 parts magnesium hydroxide, and 8 parts sintering aid (manganese dioxide and silicon tetraboride in a 1:1 mass ratio).

[0040] The ceramic tape prepared in this example is prepared by the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes. After casting, rolling and cutting, a 0.3mm thick ceramic tape is made.

[0041] Preparation Example 7 The ceramic tape of this preparation example has the following raw material components in the following mass proportions: 28 parts methyl vinyl silicone rubber, 15 parts vinyl silicone oil, 5.5 parts hydrogen-containing silicone oil, 3.2 parts Karstedt catalyst, 12.5 parts high-purity aluminum silicate fiber, 20.5 parts nano aluminum silicate, 11 parts nano silica, 16 parts magnesium hydroxide, and 8.5 parts sintering aid (manganese dioxide and silicon tetraboride in a 1:1 mass ratio).

[0042] The ceramic tape prepared in this example is prepared by the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes. After casting, rolling and cutting, a 0.3mm thick ceramic tape is made.

[0043] Preparation Example 8 The mass ratio of each raw material component in the external flame retardant masterbatch of this preparation example includes: 50 parts of methyl vinyl silicone rubber, 20 parts of vinyl silicone oil, 10 parts of hydrogen-containing silicone oil, 5 parts of Karstedt catalyst, 4 parts of pigment, 12-18 parts of terephthalic diisocyanate, 24 parts of hydroxylated carbon nanotubes, 38 parts of coated ammonium polyphosphate, and 10 parts of nano-kaolin.

[0044] The preparation of the external flame retardant masterbatch in this preparation example adopts the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes; then added to an extruder, and after extrusion and granulation, the external flame retardant masterbatch is obtained.

[0045] Preparation Example 9 The mass ratio of each raw material component in the external flame retardant masterbatch of this preparation example includes: 40 parts of methyl vinyl silicone rubber, 14 parts of vinyl silicone oil, 6 parts of hydrogen-containing silicone oil, 3 parts of Karstedt catalyst, 2 parts of pigment, 12 parts of terephthalic diisocyanate, 18 parts of hydroxylated carbon nanotubes, 30 parts of coated ammonium polyphosphate, and 6 parts of nano-kaolin.

[0046] The preparation of the external flame retardant masterbatch in this preparation example adopts the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes; then added to an extruder, and after extrusion and granulation, the external flame retardant masterbatch is obtained.

[0047] Preparation Example 10 The mass ratio of each raw material component in the external flame retardant masterbatch of this preparation example includes: 44 parts methyl vinyl silicone rubber, 16 parts vinyl silicone oil, 8 parts hydrogen-containing silicone oil, 4 parts Karstedt catalyst, 2 parts pigment, 15 parts terephthalic diisocyanate, 20 parts hydroxylated carbon nanotubes, 34 parts coated ammonium polyphosphate, and 8 parts nano-kaolin.

[0048] The preparation of the external flame retardant masterbatch in this preparation example adopts the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes; then added to an extruder, and after extrusion and granulation, the external flame retardant masterbatch is obtained.

[0049] Preparation Example 11 The mass ratio of each raw material component in the external flame retardant masterbatch of this preparation example includes: 46 parts methyl vinyl silicone rubber, 18 parts vinyl silicone oil, 9 parts hydrogen-containing silicone oil, 4.2 parts Karstedt catalyst, 4 parts pigment, 16 parts terephthalic diisocyanate, 22 parts hydroxylated carbon nanotubes, 36 parts coated ammonium polyphosphate, and 8.4 parts nano-kaolin.

[0050] The preparation of the external flame retardant masterbatch in this preparation example adopts the following steps: the raw material components of the formula are mixed evenly, added to a mixer, and mixed at 180~190℃ for 120 minutes; then added to an extruder, and after extrusion and granulation, the external flame retardant masterbatch is obtained.

[0051] The following are embodiments of this application.

[0052] The flame-retardant support 3 used in this embodiment is a columnar high-purity aluminosilicate fiber column, custom-made by Zhengzhou Shengshi Jinding Insulation and Refractory Materials Co., Ltd. The flame-retardant filling rope used in this embodiment was purchased from Ningjin County Fukai Cable Technology Co., Ltd.

[0053] Example 1 The manufacturing process of the B1-grade fire-resistant cable with polypropylene insulation in this embodiment includes the following steps: S1. Select purchased ceramic fireproof silicone tape and low smoke flame retardant silicone rubber masterbatch, and select the flame retardant polypropylene insulation masterbatch used in Preparation Example 1. S2. Using a chuck-type adjustable wrapping and wire-wrapping die, wrap the ceramic tape from step S1 around the core body 4 to form a 1mm thick ceramic tape layer 5. Then, using a hot extrusion device, using the flame-retardant polypropylene insulating masterbatch from step S1 as raw material, extrude a 1mm thick flame-retardant polypropylene insulating layer 6 around the ceramic tape layer 5 to obtain the inner core. S3. Arrange the inner core obtained in step S2 along the flame-retardant support 3 in the circumferential direction, place it in the 0.15mm thick ultra-thin corrugated copper sheath layer 2, fill the empty area with flame-retardant rope, and then obtain the cable blank. S4. Using the external flame retardant masterbatch from step S1 as raw material, a 1mm thick low-smoke external flame retardant layer 1 is extruded onto the cable blank using a hot extrusion equipment to obtain a B1-grade fireproof cable based on polypropylene insulation.

[0054] Example 2 The difference between this embodiment and Example 1 is that the flame-retardant polypropylene insulating masterbatch of Example 2 is selected.

[0055] Example 3 The difference between this embodiment and Example 1 is that the flame-retardant polypropylene insulating masterbatch of Example 3 was selected.

[0056] Example 4 The difference between this embodiment and Example 3 is that the ceramic tape of Preparation Example 4 and the external flame-retardant masterbatch of Preparation Example 8 are selected.

[0057] Example 5 The difference between this embodiment and Example 3 is that the ceramic tape of Preparation Example 5 and the external flame-retardant masterbatch of Preparation Example 9 were selected.

[0058] Example 6 The difference between this embodiment and Example 3 is that the ceramic tape of Preparation Example 6 and the external flame-retardant masterbatch of Preparation Example 10 are selected.

[0059] Example 7 The difference between this embodiment and Example 3 is that the ceramic tape of Preparation Example 7 and the external flame-retardant masterbatch of Preparation Example 11 were selected.

[0060] Example 8 The difference between this embodiment and embodiment 7 is that an ultra-thin corrugated copper sheath layer 2 with a thickness of 0.3 mm is used.

[0061] Comparative Example 1 This application uses low-smoke halogen-free wires and cables produced by Jiusheng Cable Technology Co., Ltd. as comparative example 1.

[0062] Comparative Example 2 This application uses BBTRZ flexible mineral-insulated fireproof cable produced by Zhejiang Gaoyuan Cable Co., Ltd. as comparative example 2 of this application.

[0063] Comparative Example 3 The difference between this comparative example and Example 7 is that the flame-retardant polypropylene insulating masterbatch was replaced with silane cross-linked polyethylene masterbatch produced by Liyang Ruipu New Materials Co., Ltd.

[0064] Comparative Example 4 The difference between this comparative example and Example 7 is that a 0.3mm thick mica tape produced by Shenzhen Shengda Electrical Accessories Co., Ltd. was used to replace the ceramic tape.

[0065] The performance of the products of Examples 1-8 and Comparative Examples 1-4 was tested. The room temperature and high temperature insulation properties and flame retardant properties of the cable sheathing materials of Examples 1-10 and Comparative Examples 1-4 were tested respectively.

[0066] Among them, the insulation performance of the wire core at room temperature is tested using the method described in GB / T 3048-2007, which tests the volume resistivity of the outer sheath of the 2mm thick inner wire core and the breakdown resistance of the outer sheath of the 2mm thick inner wire core under 1000V voltage. The high-temperature insulation performance of the wire core was tested using the method described in GB / T 31838.7-2021. The volume resistivity of the outer sheath of the 2mm thick inner wire core after being treated at 850℃ for 2 hours was maintained at 850℃. The breakdown resistance of the outer sheath of the 2mm thick inner wire core under 1000V at 850℃ was also tested under the same conditions. The flame retardant performance was tested using the method described in GB / T 2406.2-2009. The oxygen index of 1mm thick ceramic tape, flame retardant polypropylene insulation board and outer flame retardant adhesive board were tested respectively, as well as the oxygen index of the corresponding cladding materials in the comparative example. The combustion performance was tested using the method described in GB / T 2408-2008, specifically testing the combustion dripping of 1mm thick ceramic tape, flame-retardant polypropylene insulation board, and outer flame-retardant adhesive board, as well as the corresponding cladding materials in the comparative example.

[0067] The results are shown in Tables 1 and 2 below.

[0068] Table 1. Insulation performance test results of Examples 1-8 and Comparative Examples 1-4

[0069] Table 2. Insulation performance test results of Examples 1-8 and Comparative Examples 1-4

[0070] As can be seen from the data in Table 1, the fire-resistant cables prepared in Examples 1-8 of this application exhibit superior room-temperature insulation performance compared to Comparative Examples 1 and 2 of the prior art, meeting the high requirements for cable insulation performance. Furthermore, the room-temperature insulation performance of the fire-resistant cables prepared in Examples 1-8 of this application is also relatively better than that of Comparative Examples 3 and 4. Moreover, the insulation performance of the fire-resistant cables prepared in Examples 1-8 of this application at a high temperature of 850℃ is significantly improved compared to Comparative Examples 1-4, and they remain unbroken even under a high voltage of 1000V. Therefore, it is evident that the composite insulation layer composed of a specific flame-retardant polypropylene insulation 6 and a ceramic tape layer 5, used in this application, exhibits excellent insulation performance at both room and high temperatures, fully meeting the requirements for high-grade fire-resistant cables.

[0071] According to the data in Table 2, the fire-resistant cables prepared in Examples 1-8 of this application exhibit superior flame-retardant performance compared to Comparative Examples 1 and 2 of the prior art. The flame-retardant performance of the outer sheath of the conductor is significantly better than that of the cross-linked polyethylene used in Comparative Examples 1 and 2. The low-smoke flame-retardant performance of the adhesive layer of the cable outer sheath is comparable to that of the cables in Comparative Examples 1 and 2, both reaching the B1 level. Furthermore, the fire-resistant and flame-retardant performance of the fire-resistant cables prepared in Examples 1-8 of this application is also superior to that of Comparative Examples 3 and 4. Therefore, the fire-resistant cables of this application possess extremely excellent low-smoke flame-retardant performance, surpassing that of existing fire-resistant cables.

[0072] By comparing the data from Examples 1-8 and Comparative Examples 1-4 in Tables 1 and 2, it can be seen that after optimizing the ratio of the ceramic tape layer 5, the flame-retardant polypropylene insulation layer 6, and the low-smoke external flame-retardant adhesive layer 1, the low-smoke flame-retardant performance and high-temperature insulation performance of the fire-resistant cable can be further improved. Therefore, the specific flame-retardant system of the flame-retardant polypropylene insulation layer 6 of this application can work in conjunction with the specific ceramic raw material system of the ceramic tape layer 5 to better form a dense ceramic layer under high-temperature conditions, thereby achieving fireproofing and insulation effects. The optimized ratio of the ceramic tape layer 5 and the flame-retardant polypropylene insulation layer 6 further enhances the effect. The applicant believes that the magnesium hydroxide in the flame-retardant system of the flame-retardant polypropylene insulation layer 6 of this application, combined with the nano-silica in the ceramic tape layer 5 formulation, and the composite sintering aid composed of manganese dioxide and silicon tetraboride, can significantly reduce the vitrification sintering temperature of the ceramic raw materials in the ceramic tape layer 5. This allows the ceramic tape layer 5 of this application to be fully vitrified at a high temperature of 850℃, forming a dense vitrified layer, effectively improving the flame-retardant and high-temperature insulation effects. While Comparative Examples 1 and 2 also used mineral ceramic tape as the outer layer, they did not use the flame-retardant polypropylene insulation layer of this application, nor did they use the specific ceramic tape formulation of this application. At 850℃, the ceramic tape could not be fully vitrified, thus significantly affecting its high-temperature insulation performance. In addition, the specific low-smoke flame-retardant outer adhesive layer 1 designed in this application incorporates terephthalic diisocyanate and hydroxylated carbon nanotubes in its formulation. This allows for the formation of a cross-linked polyurethane network grafted with carbon nanotubes through a polyurethane reaction, which can cooperate with the silicone rubber system to improve the mechanical properties and wear resistance of the outer adhesive layer. Furthermore, the high nitrogen content of terephthalic diisocyanate allows carbon nanotubes to serve as a carbon source. Combined with ammonium polyphosphate intumescent flame retardant and nano-kaolin synergist, this forms a flame-retardant system with excellent low-smoke flame-retardant properties. The cross-linked polyurethane network grafted with carbon nanotubes can serve as a highly efficient char layer skeleton, significantly increasing the char layer formation time and density during combustion, thereby greatly improving the overall system's combustion suppression effect.

[0073] Based on the above experimental research, the applicant has made further improvements to the scheme of this application, resulting in Example 9.

[0074] Example 9 The manufacturing process of the B1-grade fire-resistant cable with polypropylene insulation in this embodiment includes the following steps: S1. Select purchased ceramic fireproof silicone tape and low smoke flame retardant silicone rubber masterbatch, and select the flame retardant polypropylene insulation masterbatch used in Preparation Example 1. S2. Using a chuck-type adjustable wrapping and wire-wrapping die, wrap the ceramic tape from step S1 around the core body 4 to form a 1mm thick ceramic tape layer 5. Then, using a hot extrusion device, using the flame-retardant polypropylene insulating masterbatch from step S1 as raw material, extrude a 1mm thick flame-retardant polypropylene insulating layer 6 around the ceramic tape layer 5 to obtain the inner core. S3. Arrange the inner core obtained in step S2 along the flame-retardant support 3 in the circumferential direction, place it in the 0.15mm thick ultra-thin corrugated copper sheath layer 2, fill the empty area with flame-retardant rope, and then obtain the cable blank. S4. Using a chuck-type adjustable wrapping die, wrap the ceramic tape from step S1 around the cable blank to form a 1mm thick ceramic tape layer 5. Then, using a hot extrusion device, using the external flame-retardant masterbatch from step S1 as raw material, extrude a 1mm thick low-smoke external flame-retardant layer 1 onto the ceramic tape layer 5 to obtain a B1-grade fireproof cable based on polypropylene insulation.

[0075] The aforementioned improvements in this application can more effectively and significantly enhance the fire resistance and flame retardancy, as well as the safety of fire-resistant cables. By adding a ceramic tape layer 5 between the ultra-thin corrugated copper sheath layer 2 and the low-smoke flame-retardant outer adhesive layer 1, the long-term fire resistance and long-term electrical insulation performance at high temperatures of the cable can be significantly improved. Under prolonged high-temperature conditions, the ceramic raw materials within the ceramic tape layer 5, with the assistance of magnesium hydroxide, nano-silica, and sintering aids in the formulation, can form a dense ceramic protective layer, providing heat insulation, fire resistance, and external insulation. This greatly delays the time it takes for high temperatures to penetrate the cable's interior and isolates combustion, thereby ensuring that the cable's interior remains in a safe environment for a long period, significantly extending the cable's stable operation time at high temperatures, and improving safety.

[0076] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A B1-grade fire-resistant cable based on polypropylene insulation, comprising an outer sheath and multiple inner cores, characterized in that, The outer sheath includes an ultra-thin corrugated copper sheath layer (2) and a low-smoke flame-retardant outer adhesive layer (1) covering the ultra-thin corrugated copper sheath layer (2); the inner core includes a core body (4), a ceramic tape layer (5) covering the core body (4), and a flame-retardant polypropylene insulation layer (6) covering the ceramic tape layer (5); a flame-retardant support (3) is provided inside the outer sheath, and the multiple inner cores are arranged circumferentially along the flame-retardant support (3) inside the outer sheath, and the remaining empty area inside the outer sheath is filled with flame-retardant rope; The mass ratio of each raw material component of the flame-retardant polypropylene insulation layer (6) includes: 100 parts of PP resin, 14-16 parts of nano silica, 10-12 parts of maleic anhydride grafted polyolefin elastomer, 36-40 parts of magnesium hydroxide, 6-10 parts of zinc borate, 0.4-0.6 parts of NP-657 nucleating agent, and 0.3-0.5 parts of composite antioxidant.

2. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 1, characterized in that, The mass ratio of each raw material component in the low-smoke external flame-retardant adhesive layer (1) includes: 40-50 parts of methyl vinyl silicone rubber, 14-20 parts of vinyl silicone oil, 6-10 parts of hydrogen-containing silicone oil, 3-5 parts of Karstedt catalyst, 2-4 parts of pigment, 12-18 parts of terephthalic diisocyanate, 18-24 parts of hydroxylated carbon nanotubes, 30-38 parts of coated ammonium polyphosphate, and 6-10 parts of nano-kaolin.

3. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 2, characterized in that, The mass ratio of each raw material component in the low-smoke external flame-retardant adhesive layer (1) includes: 44-46 parts of methyl vinyl silicone rubber, 16-18 parts of vinyl silicone oil, 8-9 parts of hydrogen-containing silicone oil, 4-4.2 parts of Karstedt catalyst, 2-4 parts of pigment, 15-16 parts of terephthalic diisocyanate, 20-22 parts of hydroxylated carbon nanotubes, 34-36 parts of coated ammonium polyphosphate, and 8-8.4 parts of nano-kaolin.

4. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 1, characterized in that, The mass ratio of each raw material component in the ceramic tape layer (5) includes: 20-30 parts of methyl vinyl silicone rubber, 10-20 parts of vinyl silicone oil, 4-8 parts of hydrogen-containing silicone oil, 2-4 parts of Karstedt catalyst, 10-14 parts of high-purity aluminum silicate fiber, 18-22 parts of nano aluminum silicate, 8-12 parts of nano silicon dioxide, 14-18 parts of magnesium hydroxide, and 6-10 parts of sintering aid.

5. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 4, characterized in that, The mass ratio of each raw material component in the ceramic tape layer (5) includes: 26-28 parts of methyl vinyl silicone rubber, 14-15 parts of vinyl silicone oil, 5-5.5 parts of hydrogen-containing silicone oil, 2.8-3.2 parts of Karstedt catalyst, 12-12.5 parts of high-purity aluminum silicate fiber, 20-20.5 parts of nano aluminum silicate, 10-11 parts of nano silicon dioxide, 15-16 parts of magnesium hydroxide, and 8-8.5 parts of sintering aid.

6. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 4, characterized in that, The sintering aid is composed of manganese oxide and silicon tetraboride, and the mass ratio of manganese oxide to silicon tetraboride is 1~1.5:

1.

7. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 1, characterized in that, The thickness of the ultra-thin corrugated copper sheath layer (2) is 0.15~0.3mm.

8. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 1, characterized in that, The flame-retardant support (3) is made of high-purity aluminum silicate fiber column.

9. The B1-grade fire-resistant cable based on polypropylene insulation according to claim 1, characterized in that, A ceramic tape layer (5) is also provided between the low-smoke flame-retardant adhesive layer (1) and the ultra-thin corrugated copper sheath layer (2).

10. A manufacturing process for a Class B1 fire-resistant cable based on polypropylene insulation as described in claim 1, characterized in that, Includes the following steps: S1. Preparation of ceramic tape, flame-retardant polypropylene insulating masterbatch and external flame-retardant adhesive masterbatch; S2. Wrap the ceramic tape prepared in step S1 around the outside of the wire core body (4) using a chuck-type adjustable wrapping and wire die to form a ceramic tape layer (5). Then, use a hot extrusion equipment to extrude a flame-retardant polypropylene insulation layer (6) on the outside of the ceramic tape layer (5) using the flame-retardant polypropylene insulation masterbatch prepared in step S1 as raw material to obtain the inner wire core. S3. Arrange the inner core obtained in step S2 along the circumference of the flame-retardant support (3), place it in the ultra-thin corrugated copper sheath layer (2), fill the empty area with flame-retardant rope, and then obtain the cable blank. S4. Using the flame-retardant masterbatch prepared in step S1 as raw material, a low-smoke flame-retardant adhesive layer (1) is extruded onto the cable blank using a hot extrusion equipment to obtain a B1-grade fireproof cable based on polypropylene insulation.

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