Ultra-high temperature fireproof cable based on aerogel composite ceramic fiber and preparation method thereof

Abstract

The application discloses an aerogel composite ceramic fiber-based ultrahigh-temperature fireproof cable and a preparation method thereof, relates to the field of cable preparation, and prepares a rubber compound with a radiation sensitizer and a thermal initiator, and carries out calendering and pre-crosslinking treatment on the rubber compound to obtain a carrier tape, then coats radiation-crosslinkable silicone rubber on the carrier tape to obtain a composite tape with an interface layer; a mixed slurry is prepared, and is converted into a fiber paper base material, then the fiber paper base material is subjected to impregnation treatment to obtain an aerogel composite ceramic fiber paper, then a reaction layer is formed on the aerogel composite ceramic fiber paper to obtain a composite paper; the composite tape and the composite paper are wrapped around a cable core, then irradiation treatment is carried out, and after the treatment, an irradiation-crosslinked cable core is obtained; a buffer material is coated on the irradiation-crosslinked cable core to obtain a buffer layer wrapped cable core, and a sheath is formed on the buffer layer wrapped cable core through extrusion molding to obtain the ultrahigh-temperature fireproof cable. The application solves the problem that preceramization treatment and flexibility are incompatible.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing, and in particular to ultra-high temperature fireproof cables based on aerogel composite ceramic fibers and their preparation methods. Background Technology

[0002] In high-rise buildings, rail transit, nuclear power plants, petrochemical platforms, and other locations with extremely high fire safety requirements, the ability of power lines to continuously supply power under fire conditions is crucial to ensuring fire rescue and safe evacuation of personnel.

[0003] Cross-linked polyethylene (XLPE) insulated power cables are currently the most widely used conventional products in the medium and high voltage power cable field. Their insulation layer is composed of XLPE material, possessing excellent electrical insulation properties, mechanical strength, and chemical corrosion resistance, and their manufacturing cost is relatively low, making them dominant in power transmission under normal conditions. However, XLPE insulated cables have inherent fire resistance defects: their insulation material undergoes thermal decomposition at high temperatures. When the temperature reaches its ignition point, XLPE will burn, producing large amounts of dense smoke and corrosive gases. Furthermore, the integrity of the circuit cannot be maintained under fire conditions, typically only maintaining power supply capability for a few minutes to tens of minutes. Therefore, in locations with extremely high fire safety requirements, such as high-rise buildings, rail transit, nuclear power plants, and petrochemical platforms, conventional XLPE insulated power cables cannot meet the demand for continuous power supply during a fire, necessitating the use of special cables with fire-resistant properties.

[0004] In recent years, ultra-high temperature fire-resistant cables based on aerogel composite ceramic fibers have attracted widespread attention due to their excellent thermal insulation and fire resistance properties. Aerogel has an extremely low thermal conductivity, while ceramic fibers possess excellent high-temperature resistance; the fire-resistant layer obtained by combining the two can achieve excellent thermal insulation and fire resistance under ultra-high temperature conditions. However, in the development of ultra-high temperature fire-resistant cables based on aerogel composite ceramic fibers, there is a problem of incompatibility between pre-ceramization treatment and flexibility. Specifically, in order for the aerogel composite ceramic fiber layer to quickly form a dense ceramic shell during a fire, the ceramic fibers usually need to be pre-sintered to form preliminary sintering necks between the fibers and fix the aerogel powder. However, the pre-sintered ceramic fiber tape becomes significantly brittle and hard, making it extremely easy to break during the wrapping process. It also cannot tightly adhere to the curved cable core surface, and gaps are easily generated at the overlap, resulting in structural defects in the fire-resistant layer. Conversely, if pre-sintering is not performed, although the ceramic fiber tape remains flexible at room temperature, its strength is low, the bonding force between the fibers is weak, and the aerogel powder is easy to fall off. Furthermore, under fire conditions, the fiber layer that has not been pre-sintered cannot quickly sinter to form a dense shell in a short time, the ceramicization reaction is delayed, and it is difficult to achieve the ultra-high temperature fire resistance rating.

[0005] Therefore, a method for preparing an ultra-high temperature fireproof cable based on aerogel composite ceramic fiber is proposed to solve the problem of incompatibility between pre-ceramization treatment and flexibility. Summary of the Invention

[0006] The purpose of this invention is to provide an ultra-high temperature fireproof cable based on aerogel composite ceramic fiber and its preparation method, thereby solving the problem of incompatibility between pre-ceramization treatment and flexibility.

[0007] To achieve this objective, the present invention adopts the following technical solution: A method for preparing ultra-high temperature fire-resistant cables based on aerogel composite ceramic fibers, characterized in that the preparation method includes the following steps: Step S1: Prepare a compound rubber containing a radiation sensitizer and a thermal initiator, and calender and pre-crosslink it to obtain a carrier belt. Then, coat the carrier belt with a radiation-crosslinkable silicone rubber to obtain a composite belt with an interface layer. Step S2: Prepare a mixed slurry and convert it into a fiber paper substrate. Then, impregnate the fiber paper substrate to obtain aerogel composite ceramic fiber paper. Subsequently, form a reaction layer on the aerogel composite ceramic fiber paper to obtain composite paper. Step S3: Wrap the composite tape and composite paper around the cable core, and then perform irradiation treatment. After the treatment is completed, an irradiated cross-linked cable core is obtained. Step S4: Wrap a buffer material around the irradiated cross-linked cable core to obtain a buffer layer wrapped around the cable core, and then form a sheath on the buffer layer wrapped around the cable core by extrusion molding to obtain an ultra-high temperature fireproof cable.

[0008] Step S1 specifically includes the following steps: Step S11: Mix methyl vinyl silicone rubber raw rubber, fumed silica and hydroxyl silicone oil at 100-120℃ for 30-60 min to obtain a mixed rubber; then add additives containing TAIC and DCP to the mixed rubber and mix at ≤40℃ for 30-60 min to obtain a compounded rubber. Step S12: After degassing the compound, roll it at a roller temperature of 40-60℃ to obtain a roll material; then pass the roll material through a hot air vulcanizing box at a temperature of 160-170℃ within 30-60 seconds. After passing through, the roll material is cooled to room temperature to obtain a carrier belt. Step S13: Apply molten methyl vinyl silicone rubber raw material at 80-100℃ onto the carrier belt, and then cool it to obtain a composite belt with an interface layer formed on the carrier belt.

[0009] In step S11, the additives further include mica powder, wollastonite, low-melting-point borosilicate glass powder, and silane coupling agent KH-550; by mass parts, the methyl vinyl silicone rubber raw rubber is 100 parts, the fumed silica is 35-45 parts, the hydroxyl silicone oil is 3-5 parts, the TAIC is 0.8-1.5 parts, the DCP is 0.2-0.5 parts, the mica powder is 40-60 parts, and the wollastonite is 30-50 parts. The low-melting-point borosilicate glass powder is 20-30 parts, the silane coupling agent KH-550 is 1-2 parts; the specific surface area of ​​the fumed silica is 200-300 m² / g, the viscosity of the hydroxyl silicone oil is 20-50 cSt, the particle size of the mica powder is 10-20 μm, the particle size of the wollastonite is 5-15 μm, and the softening point of the low-melting-point borosilicate glass powder is 480-520℃ and the particle size D50 is 5-10 μm.

[0010] In step S12, the thickness of the roll material is 0.4-0.6 mm; the gel content of the carrier tape is 10-20%, the tensile strength is >3 MPa, and more than 80% of unreacted vinyl groups are retained. In step S13, the thickness of the interface layer is 0.05-0.10 mm, and the thickness of the composite strip is 0.45-0.70 mm.

[0011] Step S2 specifically includes the following steps: Step S21: Mix aluminosilicate ceramic fiber, polyacrylamide, and water to obtain fiber slurry; mix silica aerogel powder and low-melting-point borosilicate glass powder with water to obtain filler slurry; then stir the filler slurry and fiber slurry for 5-10 minutes to obtain mixed slurry; vacuum suction and press dewater the mixed slurry to obtain wet paper web; then dry the wet paper web at 120-150℃ to obtain dry paper web; subsequently, needle-punch the dry paper web to obtain needle-punched reinforced paper web.

[0012] Step S22: After passing the needle-punched reinforced paper web through the impregnation tank, the needle-punched reinforced paper web is squeezed dry using a squeeze roller, and then dried at a temperature of 120-150℃ to obtain aerogel composite ceramic fiber paper. Step S23: Spray the silane coupling agent KH-550 solution onto the aerogel composite ceramic fiber paper and dry it under hot air at 80-100℃ for 10-20s to obtain a composite paper with a reaction layer formed on the aerogel composite ceramic fiber paper.

[0013] In step S21, by mass percentage, the aluminosilicate ceramic fiber comprises 55-65%, the silica aerogel powder comprises 20-30%, the low-melting-point borosilicate glass powder comprises 8-12%, and the polyacrylamide comprises 0.05-0.1% of the dry weight of the aluminosilicate ceramic fiber; the aluminosilicate ceramic fiber has a diameter of 3-5 μm and a length of 5-10 mm, the silica aerogel powder has a particle size of 10-50 μm, and the low-melting-point borosilicate glass powder is the same as that in step S11; the needle punching density is 80-120 needles / cm. 2 The depth is 5-8mm; In step S22, the impregnation tank is filled with a polyacrylate emulsion with a solid content of 40-50%, the polyacrylate binder content in the needle-punched reinforced paper web after squeezing is 3-5 wt%, and the thickness of the aerogel composite ceramic fiber paper is 0.6-1.0 mm. In step S23, the concentration of the silane coupling agent KH-550 solution is 0.5-1.0 wt%, and the thickness of the reaction layer is 5 μm.

[0014] Step S3 specifically includes the following steps: Step S31: Wrap the composite tape and composite paper onto the cable core sequentially at a wrapping speed of 10-15 m / min to obtain a wrapped cable core; Step S32: The wrapped cable core is rotated in the electron beam irradiation chamber, and then cooled to room temperature after irradiation to obtain the irradiated cross-linked cable core.

[0015] In step S31, the overlap rate of the composite tape and the composite paper is 25-30%, the wrapping tension is <5N, and the interface layer and the reaction layer are in contact when the composite tape is wrapped. In step S32, the electron energy of the electron beam irradiation chamber is 1.5-2.0 MeV, the beam current intensity is 20-40 mA, the irradiation dose is 100-150 kGy, and the linear velocity is 10-15 m / min.

[0016] Step S4 specifically includes the following steps: Step S41: Wrap glass fiber composite aluminum foil tape around the irradiated cross-linked cable core to obtain a buffer layer wrapped cable core; Step S42: Add LSZH granules to an extruder to obtain a melt, and coat the cable core with a buffer layer at a temperature of 80-100℃. After cooling in a water tank, an ultra-high temperature fireproof cable with a buffer layer forming a sheath on the cable core is obtained.

[0017] In step S41, the wrapping speed of the glass fiber composite aluminum foil strip is 10-20 m / min, the overlap rate is 15-20%, the tension is <3N, and the thickness of the glass fiber composite aluminum foil strip is 0.15-0.20 mm. In step S42, the temperature of the extruder is 140-180℃, the water tank includes initial cooling at 40-50℃ and secondary cooling at 20-30℃, and the thickness of the sheath is 1.5-2.5mm.

[0018] The ultra-high temperature fireproof cable based on aerogel composite ceramic fiber is obtained by the preparation method described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an ultra-high temperature fire-resistant cable based on aerogel composite ceramic fiber and its preparation method. Addressing the incompatibility between pre-ceramization treatment and flexibility, this method systematically unifies the flexibility requirements during processing with the fire resistance requirements during service. Firstly, the composite tape achieves sufficient processing strength before wrapping while retaining the activity of subsequent reactions, avoiding deformation or breakage of uncrosslinked materials under wrapping tension. The composite paper, without pre-sintering, achieves sufficient strength and low dust loss to meet wrapping requirements through physical anchoring and auxiliary reinforcement, and pre-constructs an active surface. During the wrapping process, both the composite tape and composite paper are in a processable flexible state, allowing for tight adhesion to the cable core and seamless wrapping. Subsequent overall irradiation treatment deeply crosslinks the composite tape to achieve thermosetting properties, while chemically bridging the interface layer and reaction layer, permanently transforming the flexible physical contact during wrapping into an integrated chemical bond structure. This completely solves the brittle fracture processing problem caused by pre-sintering without sacrificing fire resistance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0022] Figure 1 This is a flowchart of the preparation method in this invention. Detailed Implementation

[0023] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0025] Please see Figure 1 The preparation method of the ultra-high temperature fireproof cable based on aerogel composite ceramic fiber in this embodiment includes the following steps: Step S1: Prepare a compound rubber containing a radiation sensitizer and a thermal initiator, and calender and pre-crosslink it to obtain a carrier belt. Then, coat the carrier belt with a radiation-crosslinkable silicone rubber to obtain a composite belt with an interface layer. Step S2: Prepare a mixed slurry and convert it into a fiber paper substrate. Then, impregnate the fiber paper substrate to obtain aerogel composite ceramic fiber paper. Subsequently, form a reaction layer on the aerogel composite ceramic fiber paper to obtain composite paper. Step S3: Wrap the composite tape and composite paper around the cable core, and then perform irradiation treatment. After the treatment is completed, an irradiated cross-linked cable core is obtained. Step S4: Wrap a buffer material around the irradiated cross-linked cable core to obtain a buffer layer wrapped around the cable core, and then form a sheath on the buffer layer wrapped around the cable core by extrusion molding to obtain an ultra-high temperature fireproof cable.

[0026] Step S1: Prepare a compound rubber containing a radiation sensitizer and a thermal initiator, and calender and pre-crosslink it to obtain a carrier belt. Then, coat the carrier belt with a radiation-crosslinkable silicone rubber to obtain a composite belt with an interface layer. Step S1 specifically includes the following steps: Step S11: Mix methyl vinyl silicone rubber raw rubber, fumed silica and hydroxyl silicone oil at 100-120℃ for 30-60 min to obtain a mixed rubber; then add additives containing TAIC and DCP to the mixed rubber and mix at ≤40℃ for 30-60 min to obtain a compounded rubber. In step S11, the additives also include mica powder, wollastonite, low-melting-point borosilicate glass powder, and silane coupling agent KH-550; by mass parts, 100 parts of methyl vinyl silicone rubber raw rubber, 35-45 parts of fumed silica, 3-5 parts of hydroxyl silicone oil, 0.8-1.5 parts of TAIC, 0.2-0.5 parts of DCP, 40-60 parts of mica powder, 30-50 parts of wollastonite, 20-30 parts of low-melting-point borosilicate glass powder, and 1-2 parts of silane coupling agent KH-550; the specific surface area of ​​the fumed silica is 200-300 m². 2 / g, the viscosity of hydroxyl silicone oil is 20-50cSt, the particle size of mica powder is 10-20μm, the particle size of wollastonite is 5-15μm, the softening point of low melting point borosilicate glass powder is 480-520℃, and the particle size D50 is 5-10μm.

[0027] Step S12: After degassing the rubber compound, roll it at a roller temperature of 40-60℃ to obtain a roll material; then pass the roll material through a hot air vulcanizing box at a temperature of 160-170℃ within 30-60 seconds. After passing through, the roll material is cooled to room temperature to obtain a carrier belt; the rubber compound is thinly passed through an open mill to achieve degassing; the degassing process is well known to those skilled in the art and will not be described in this embodiment.

[0028] In step S12, the thickness of the roll material is 0.4-0.6 mm; the gel content of the carrier tape is 10-20%, the tensile strength is >3 MPa, and more than 80% of the unreacted vinyl groups are retained; Step S13: Apply molten methyl vinyl silicone rubber raw material at 80-100℃ onto the carrier belt, and then cool it to obtain a composite belt with an interface layer formed on the carrier belt.

[0029] In step S13, the thickness of the interface layer is 0.05-0.10 mm, and the thickness of the composite strip is 0.45-0.70 mm.

[0030] It should be noted that in step S1, after the methyl vinyl silicone rubber raw rubber, fumed silica, and hydroxyl silicone oil are mixed at a high temperature of 100-120℃, the silanol groups on the surface of the fumed silica undergo a condensation reaction with the silicone rubber molecular chains and hydroxyl silicone oil, forming Si-O-Si chemical bonds, which makes the silica uniformly dispersed and anchored to the rubber network. The hydroxyl silicone oil also acts as a structure control agent to prevent excessive reaction between the silica and the raw rubber, which would lead to material hardening. In the subsequent step S, after cooling to below 40℃, mica powder, wollastonite, low-melting-point borosilicate glass powder, silane coupling agent KH-550, TAIC (trimethylene isocyanurate), and DCP (diisopropylbenzene peroxide) are added. The silane coupling agent forms an organic modification layer on the surface of the inorganic filler, improving the interfacial compatibility between the filler and the rubber matrix, and making the filler uniformly distributed in the continuous rubber phase, forming a highly filled compound. After the compound is calendered into 0.4-0.6 mm rolls, it is vulcanized in a 160-170℃ hot air vulcanizing oven. The DCP thermally decomposes to generate free radicals, initiating slight cross-linking of the silicone rubber molecular chains. At this point, the roll transforms from a thermoplastic state to a slightly cross-linked thermosetting elastomer, increasing its tensile strength from 1 MPa to over 3 MPa, while still retaining a large amount of unreacted vinyl groups. Subsequently, methyl vinyl silicone rubber raw material is hot-melt coated onto the carrier belt at 80-100℃, forming a 0.05-0.10 mm interface layer upon cooling. This interface layer is filler-free, remains uncross-linked, and has a tacky surface, providing active groups for subsequent co-crosslinking with the interface layer and chemical bridging with the outer layer.

[0031] It is known that step S1 uses DCP to initiate mild pre-crosslinking, enabling the carrier tape to obtain sufficient strength (tensile strength > 3MPa) before wrapping, avoiding tensile deformation or breakage of the uncrosslinked tape under wrapping tension, and achieving a balance between processing strength and interfacial activity. The interface layer is formed by solvent-free hot melt coating, avoiding swelling damage and small molecule migration of the carrier tape caused by solvent-based coating, ensuring the chemical purity and thickness uniformity of the interface layer. Both the interface layer and the carrier tape use methyl vinyl silicone rubber raw rubber, whose surface tack and abundant vinyl groups provide a reaction basis for co-crosslinking with the composite tape during subsequent overall irradiation, enabling the carrier tape to have sufficient mechanical strength and flexibility during the room temperature wrapping stage to meet the requirements of high-speed wrapping process. At the same time, the interface layer, as an active connecting layer, stores chemical bonding capacity, creating conditions for subsequent integrated crosslinking, thus completely avoiding the brittle fracture problem caused by traditional pre-sintering.

[0032] Understandably, in traditional solutions, pre-sintering is required to enable rapid ceramicization of the fiber layer during a fire. However, pre-sintering makes the material brittle and unable to be wrapped. If pre-sintering is omitted, the fiber layer strength is insufficient at room temperature, and ceramicization is delayed during a fire. Step S1 utilizes the cross-linking properties of methyl vinyl silicone rubber raw material to achieve rigidity of the carrier belt before wrapping through slight pre-crosslinking, solving the processing deformation problem caused by excessive flexibility. The retained unreacted vinyl groups allow for deep crosslinking and interfacial co-crosslinking through overall irradiation after wrapping, thus ensuring the composite belt maintains structural stability during subsequent sheath extrusion and high-temperature fire conditions. Step S1 replaces pre-sintering with slight pre-crosslinking, decoupling the ceramicization function from processing flexibility. The composite belt provides processing strength and interfacial stability during the processing stage, while the inorganic system in the composite paper provides fire resistance during the fire stage. The two form an integral structure through the interfacial layer during irradiation, thus completely solving the brittle fracture processing problem caused by pre-sintering without sacrificing fire resistance.

[0033] It is worth noting that TAIC, as a radiation sensitizer, requires a dosage of 0.8-1.5 parts to ensure the irradiation effect. A dosage below 0.8 parts results in insufficient crosslinking efficiency, while a dosage above 1.5 parts leads to excessive crosslinking and material brittleness. DCP dosage is controlled at 0.2-0.5 parts, combined with hot air vulcanization conditions of 160-170℃ and 30-60s, ensuring a mild pre-crosslinking effect. This guarantees the tensile strength of the carrier strip while avoiding excessive crosslinking and consumption of too much vinyl. If the hot air vulcanization temperature is below 160℃, DCP decomposes incompletely; above 170℃, the crosslinking reaction is too vigorous, causing the carrier strip to lose its activity for subsequent irradiation crosslinking. A calendering thickness of 0.4-0.6mm balances mechanical strength and wrapping flexibility; too thin and the strength is insufficient, too thick and the bending stiffness increases. An interface layer thickness of 0.05-0.10mm ensures sufficient penetration into the pores of the composite paper during irradiation to form physical interlocking, while avoiding excessive thickness that would reduce the cohesive strength of the interface layer itself.

[0034] Step S2: Prepare a mixed slurry and convert it into a fiber paper substrate. Then, impregnate the fiber paper substrate to obtain aerogel composite ceramic fiber paper. Subsequently, form a reaction layer on the aerogel composite ceramic fiber paper to obtain composite paper. Step S2 specifically includes the following steps: Step S21: Mix aluminosilicate ceramic fiber, polyacrylamide, and water to obtain fiber slurry; mix silica aerogel powder and low-melting-point borosilicate glass powder with water to obtain filler slurry; then stir the filler slurry and fiber slurry for 5-10 minutes to obtain mixed slurry; vacuum suction and press dewater the mixed slurry to obtain wet paper web; then dry the wet paper web at 120-150℃ to obtain dry paper web; subsequently, needle-punch the dry paper web to obtain needle-punched reinforced paper web.

[0035] In step S21, by mass percentage, the aluminosilicate ceramic fiber comprises 55-65%, the silica aerogel powder comprises 20-30%, the low-melting-point borosilicate glass powder comprises 8-12%, and the polyacrylamide comprises 0.05-0.1% of the dry weight of the aluminosilicate ceramic fiber; the aluminosilicate ceramic fiber has a diameter of 3-5 μm and a length of 5-10 mm, the silica aerogel powder has a particle size of 10-50 μm, and the low-melting-point borosilicate glass powder is the same as that in step S11; the needle-punching density is 80-120 needles / cm. 2 The depth is 5-8mm; Step S22: After passing the needle-punched reinforced paper web through the impregnation tank, the needle-punched reinforced paper web is squeezed dry using a squeeze roller, and then dried at a temperature of 120-150℃ to obtain aerogel composite ceramic fiber paper. In step S22, the impregnation tank contains a polyacrylate emulsion with a solid content of 40-50%, the polyacrylate binder content in the needle-punched reinforced paper web after squeezing is 3-5 wt%, and the thickness of the aerogel composite ceramic fiber paper is 0.6-1.0 mm. Step S23: Spray the silane coupling agent KH-550 solution onto the aerogel composite ceramic fiber paper and dry it under hot air at 80-100℃ for 10-20s to obtain a composite paper with a reaction layer formed on the aerogel composite ceramic fiber paper.

[0036] In step S23, the concentration of the silane coupling agent KH-550 solution is 0.5-1.0 wt%, and the thickness of the reaction layer is 5 μm.

[0037] The impregnation and needle-punching reinforcement methods in step S2 are well known to those skilled in the art and will not be described in this embodiment.

[0038] It should be noted that in step S2, the aluminosilicate ceramic fibers are 5-10 mm long and 3-5 μm in diameter, forming a fiber network skeleton in the aqueous phase. Polyacrylamide acts as a retention aid, its polymer chains adsorbing onto the fiber surface through hydrogen bonding and electrostatic interactions, improving the retention rate of subsequent fillers on the fibers. Subsequently, silica aerogel powder and low-melting-point borosilicate glass powder are mixed with water to prepare a filler slurry. The filler slurry is then mixed and stirred with the fiber slurry for 5-10 minutes to form a mixed slurry. These fillers are uniformly distributed in the gaps between the fiber network. After vacuum suction and pressing dewatering, the water is removed from the mixed slurry, and the fibers and fillers form a wet paper web. During the drying process at 120-150℃, the moisture in the wet paper web evaporates, and the hydrogen bonds and physical entanglements between the fibers provide initial strength. Subsequently, the dried paper web is needle-punched for reinforcement. The barbs on the needles cause the fibers to shift and entangle in the vertical direction, forming a three-dimensional network structure. This physically anchors the aerogel powder within the fiber network, reducing the dust loss rate of the needle-punched reinforced paper web to below 3%. As the needle-punched reinforced paper web passes through the impregnation tank, the polyacrylate emulsion penetrates into the pores of the fiber network. After drying with controlled liquid retention by the squeeze rollers, the polyacrylate forms a film on the fiber surface, further bonding the fibers and fillers. This increases the tensile strength of the aerogel composite ceramic fiber paper to over 1.5 MPa. Simultaneously, the binder further solidifies the fibers and aerogel powder, reducing the dust loss rate of the final product to below 1%. Finally, a silane coupling agent solution, KH-550, is sprayed on. The ethoxy groups in the KH-550 molecules hydrolyze and react with the silanol groups on the fiber surface to form siloxane bonds, anchoring the amino groups on the surface of the aerogel composite ceramic fiber paper, forming a 5 μm thick reaction layer. This reaction layer provides active sites for subsequent chemical bridging with the interface layer of the composite tape.

[0039] It is known that step S2, by employing a process sequence of needle punching followed by impregnation, allows the needle punching to fully entangle the fibers into a three-dimensional network without the interference of binder. The subsequent impregnation with polyacrylate binder only serves an auxiliary reinforcing role. The polyacrylate content in the needle-punched reinforced paper web is controlled at 3-5 wt%, ensuring that the tensile strength of the aerogel composite ceramic fiber paper meets the requirements for wrapping processing, while avoiding the impact of residual carbon from high-content binders on the ceramicization density at high temperatures. Low-melting-point borosilicate glass powder is uniformly distributed in the fiber network. Under fire conditions, the glass powder melts and wets the ceramic fibers, promoting the burning between the fibers. The shell is formed, and the silica aerogel powder provides an ultra-low thermal conductivity (<0.035W / m·K), which delays the conduction of heat to the cable core. The reaction layer formed by spraying silane coupling agent KH-550 has amino groups on its surface that can chemically react with the interface layer of the composite tape during subsequent overall irradiation, achieving chemical bonding between the inorganic fiber paper and the organosilicon rubber. This allows the composite paper to have the mechanical strength to wrap and a low dusting rate at room temperature, and to sinter into a dense ceramic shell in the event of a fire. At the same time, the chemical activity provided by the reaction layer achieves a high-strength interface bond with the composite tape, preventing interlayer slippage or peeling.

[0040] Understandably, in traditional solutions, pre-sintering is required to rapidly ceramicize the ceramic fiber layer during a fire. However, pre-sintering makes the fiber layer brittle and unable to be wrapped. If pre-sintering is omitted, the fiber layer lacks sufficient strength at room temperature, and the aerogel easily detaches. Step S2 employs a composite reinforcement method combining needle-punching physical anchoring and a small amount of decomposable adhesive. Without any pre-sintering, the aerogel composite ceramic fiber paper achieves sufficient processing strength and low dust loss. Simultaneously, the three-dimensional network structure formed by needle punching maintains the flexibility of the fiber paper, adapting to bending deformation during cable wrapping. Furthermore, the reaction layer introduced in step S2, formed by the silane coupling agent KH-550, works synergistically with the interface layer of the composite tape. The interface layer is uncrosslinked methyl vinyl silicone rubber raw rubber with a sticky and vinyl surface, while the reaction layer has amino groups on its surface. During the wrapping process in the subsequent step S3, the interface layer and the reaction layer are in close contact. Subsequently, during overall irradiation, a chemical bridging reaction occurs between the two, firmly bonding the inorganic outer layer and the organic inner layer. This method fully imparts ceramicization to the composite paper and processing flexibility and interface bonding to the composite tape. The two are integrated through chemical bonding in step S3, thereby avoiding the brittle fracture problem caused by pre-sintering without sacrificing refractory performance.

[0041] During the fire's heating process, when the temperature reaches 300-400℃, the silicone rubber component in the composite tape gradually undergoes thermal decomposition, but the composite paper still maintains an intact wrapping structure. When the temperature further rises to 500-700℃, the low-melting-point borosilicate glass powder begins to soften and melt, promoting the formation of a sintered connection structure between the aluminosilicate ceramic fibers. As the temperature continues to rise, the inorganic system in the composite paper gradually forms a continuous ceramic shell. Even if the organic components in the composite tape further carbonize or fail, the inorganic ceramic shell formed by the composite paper can still maintain continuous coverage of the cable core, thereby maintaining the integrity of the line and its thermal insulation performance.

[0042] It is worth noting that in step S2, if the content of aluminosilicate ceramic fibers is below 55%, the fiber network skeleton will be sparse, resulting in insufficient paper web strength; if it is above 65%, the content of silica aerogel powder and low-melting-point borosilicate glass powder will decrease, leading to a decline in thermal insulation performance and ceramicization effect. If the content of silica aerogel powder is below 20%, the thermal conductivity will increase; if it is above 30%, the composite paper strength will decrease and the dust shedding rate will increase. If the content of polyacrylate is below 3%, the tensile strength will be <1.0 MPa, failing to meet the wrapping tension requirements; if it is above 5%, the residual carbon from high-temperature decomposition will increase, affecting the compactness of the ceramicized product. If the needle punching density is below 80 needles / cm², the thermal conductivity will be significantly reduced. 2 Insufficient fiber entanglement results in low interlaminar peel strength; if it exceeds 120 needles / cm... 2 Excessive needle punching damages the fiber structure, leading to a decrease in the mechanical properties of the paper web. In step S2, the process sequence of needle punching followed by impregnation is crucial. If impregnation precedes needle punching, the fibers are locked after the binder cures, preventing them from sliding during needle punching, significantly reducing the entanglement effect, and consequently decreasing the paper web strength. If the concentration of the silane coupling agent KH-550 solution is below 0.5%, the amino density of the reaction layer is insufficient, resulting in limited interfacial chemical bridging; if it is above 1.0%, the coupling agent forms multiple layers of physical adsorption on the fiber surface, which are easily detached after drying, increasing costs. Under the influence of these parameters, the composite paper is ensured to have sufficient strength and flexibility during processing, and can form a dense ceramic shell in the event of a fire, achieving chemical bonding through the reaction layer and the interfacial layer.

[0043] Step S3: Wrap the composite tape and composite paper around the cable core (the cable core includes a conductor and an insulation layer covering the outside of the conductor, the insulation layer being cross-linked polyethylene), and then perform irradiation treatment. After the treatment is completed, an irradiated cross-linked cable core is obtained. Step S3 specifically includes the following steps: Step S31: Wrap the composite tape and composite paper onto the cable core sequentially at a wrapping speed of 10-15 m / min to obtain a wrapped cable core; In step S31, the overlap rate of the composite tape and the composite paper is 25-30%, the wrapping tension is <5N, and the interface layer and the reaction layer are in contact when the composite tape is wrapped.

[0044] Step S32: Rotate the wrapped cable core in the electron beam irradiation chamber, and cool it to room temperature after irradiation to obtain the irradiated cross-linked cable core.

[0045] In step S32, the electron energy of the electron beam irradiation chamber is 1.5-2.0 MeV, the beam current intensity is 20-40 mA, the irradiation dose is 100-150 kGy, and the linear velocity is 10-15 m / min.

[0046] In step S3, the composite tape and composite paper are wrapped by a wrapping machine. The specific wrapping method is well known to those skilled in the art and will not be described in this embodiment.

[0047] It should be noted that in step S3, the composite tape (interface layer facing outward) and composite paper (reaction layer facing inward) are sequentially wrapped around the cable core surface at a wrapping speed of 10-15 m / min, an overlap rate of 25-30%, and a wrapping tension of <5 N. Under wrapping tension, the composite tape and composite paper are tightly bonded, and the interface layer and reaction layer form physical contact. In this process, the interface layer of the composite tape is uncrosslinked methyl vinyl silicone rubber raw rubber, whose molecular chains possess flexibility and surface tack. The reaction layer of the composite paper is a fiber surface treated with silane coupling agent KH-550, distributed with amino active groups. Under wrapping pressure, the uncrosslinked silicone rubber molecular chains of the interface layer undergo localized creep, partially penetrating into the micropores and fiber gaps on the surface of the composite paper, forming a preliminary mechanical interlock. The wrapped cable core was then placed in an electron beam irradiation chamber and rotated. Under electron energies of 1.5-2.0 MeV, beam currents of 20-40 mA, and irradiation doses of 100-150 kGy, high-energy electrons penetrated the laminated structure of the composite tape and composite paper. The high-energy electron beam excited the methyl vinyl silicone rubber molecular chains and TAIC sensitizer in the composite tape, generating free radicals and initiating a deep cross-linking reaction. TAIC, as a multifunctional monomer, participated in the formation of the cross-linking network. Simultaneously, the uncross-linked methyl vinyl silicone rubber raw rubber in the interface layer and the methyl vinyl silicone rubber raw rubber in the carrier tape formed a chemically bonded integrated structure. The free radicals generated on the molecular chains of the interface layer reacted with the active groups on the surface of the composite paper's reactive layer, thereby improving the interlayer bonding stability between the composite tape and composite paper, ensuring that the composite paper maintains an intact covering structure during subsequent sheath extrusion and the initial stage of fire heating. In addition, the rotation of the wrapped cable core ensured the circumferential uniformity of the electron beam irradiation, controlling the absorbed dose deviation in each direction of the cable core within ±15%.

[0048] It is known that step S3 uses overall electron beam irradiation instead of segmented thermal crosslinking. The irradiation dose of 100-150 kGy transforms the carrier tape from a slightly pre-crosslinked state to a deeply crosslinked state and improves the interlayer bonding stability between the composite tape and the composite paper, thereby avoiding interlayer slippage or peeling during subsequent sheath extrusion, bending, or the initial stage of fire heating. During the irradiation process, the uncrosslinked methyl vinyl silicone rubber raw rubber of the interface layer undergoes an in-situ chemical reaction with the amino group of the reaction layer, realizing the chemical bonding of the organic and inorganic interface, so that the 90° peel strength can reach more than 2 N / mm, which is much higher than the 0.5-1 N / mm of traditional physical bonding. When wrapping, the interface layer and the reaction layer are in direct contact, with an overlap rate of 25-30%, to ensure that the two layers of materials are in continuous contact across the entire cable core surface without any exposed gaps. Under the aforementioned wrapping method, the flexible physical contact during wrapping is transformed into a stable interlayer bonding structure through irradiation, enabling the composite tape and composite paper to form an integral fire-resistant structure. This maintains structural integrity during cable bending, vibration, temperature cycling, and the initial stage of fire heating, preventing interlayer slippage or peeling, and providing a complete initial structure for the formation of a continuous ceramic shell in the inorganic system of the subsequent composite paper.

[0049] Understandably, in traditional solutions, pre-sintered ceramic fiber tapes are brittle and cannot adhere tightly to the inner layer. Even after wrapping, interfacial gaps remain, allowing flames to directly burn through the refractory layer during a fire. While fiber tapes without pre-sintering offer good flexibility, they lack effective bonding with the inner layer and are prone to delamination under cable bending or thermal stress from a fire. Step S3 employs a wrapping-then-irradiation process, ensuring both the composite tape and composite paper are in a flexible, processable state during wrapping, allowing for tight adhesion to the cable core surface and achieving seamless wrapping. After wrapping, electron beam irradiation deeply cross-links the carrier tape to achieve thermosetting properties and chemically bridges the interfacial and reactive layers, firmly anchoring the composite paper to the composite tape. This eliminates the conflict between flexibility during processing and interfacial strength in the final product: the two materials are independently flexible and can be wrapped during processing, but after processing, irradiation transforms them into an integrated rigid structure. In addition, the self-rotation irradiation method used in step S3 ensures that the interface layer at each angle position of the cable core obtains sufficient cross-linking degree and chemical bridging degree, avoiding the hidden danger of poor local bonding.

[0050] It is worth noting that the selection of a wrapping speed of 10-15 m / min in step S3 is matched with the tensile strength of the composite tape and the composite paper. A speed below 10 m / min results in low production efficiency; a speed above 15 m / min increases tension fluctuations, potentially causing the composite tape or paper to break during wrapping, or leading to unstable overlap rates. An overlap rate of 25-30% ensures continuous coverage of the fire-resistant layer. Too low an overlap rate can result in exposed seams; too high an overlap rate leads to excessive material overlap, resulting in uneven outer diameter and increased costs. The wrapping tension is based on the tensile yield strength of the composite tape and composite paper; exceeding 5 N can easily cause plastic elongation or width shrinkage of the tape. The selection of an electron beam energy of 1.5-2.0 MeV ensures penetration of the total thickness of the composite tape and composite paper. Too low an energy results in insufficient load on the carrier tape and incomplete cross-linking; too high an energy may damage the conductor or the internal insulation of the cable core. The irradiation dose of 100-150 kGy and the TAIC content work synergistically: when the dose is below 100 kGy, the crosslinking is insufficient; when it is above 150 kGy, it is easy to cause excessive crosslinking and brittleness of silicone rubber, and the energy consumption increases.

[0051] Step S4: Wrap a buffer material around the irradiated cross-linked cable core to obtain a buffer layer wrapped around the cable core, and then form a sheath on the buffer layer wrapped around the cable core by extrusion molding to obtain an ultra-high temperature fireproof cable.

[0052] Step S4 specifically includes the following steps: Step S41: Wrap glass fiber composite aluminum foil tape around the irradiated cross-linked cable core to obtain a buffer layer wrapped cable core; In step S41, the wrapping speed of the glass fiber composite aluminum foil tape is 10-20 m / min, the overlap rate is 15-20%, the tension is <3 N, and the thickness of the glass fiber composite aluminum foil tape is 0.15-0.20 mm. Step S42: Add LSZH granules to an extruder to obtain a melt, and wrap the melt around the cable core with a buffer layer at a temperature of 80-100℃. After cooling in a water tank, an ultra-high temperature fireproof cable with a buffer layer forming a sheath on the cable core is obtained.

[0053] In step S42, the temperature of the extruder is 140-180℃, the water tank includes primary cooling at 40-50℃ and secondary cooling at 20-30℃, and the thickness of the sheath is 1.5-2.5mm.

[0054] It should be noted that in step S4, a glass fiber composite aluminum foil strip with a thickness of 0.15-0.20 mm (aluminum foil facing outwards to reflect radiant heat) is wrapped around the surface of the irradiated cross-linked cable core at a wrapping speed of 10-20 m / min, an overlap rate of 15-20%, and a tension of <3 N, forming a buffer layer wrapped around the cable core. This glass fiber composite aluminum foil strip consists of a glass fiber cloth layer and an aluminum foil layer. The glass fiber cloth layer is woven from glass fibers with a diameter of 5-10 μm, possessing a porous structure and high thermal resistance, while the aluminum foil layer has high reflectivity. After the buffer layer is wrapped, the surface of the irradiated cross-linked cable core is covered with a layer of low thermal conductivity material. Subsequently, LSZH (low smoke halogen-free flame-retardant polyolefin) granules are added to an extruder and melted and plasticized at a temperature of 140-180℃ to form a viscous polymer melt. The molten material is wrapped around the cable core surface of a buffer layer at 80-100℃ using a semi-extrusion die. Under an extrusion pressure of 1-3MPa, the molten material adheres tightly to the outer surface of the buffer layer. As the buffer layer wrapped around the cable core with the molten material enters a water bath for cooling, it first undergoes an initial cooling at 40-50℃ to rapidly solidify and shape the molten material, and then undergoes a second cooling at 20-30℃ to bring the sheath to room temperature. During this process, the molten material forms a continuous and uniform tubular outer sheath with a thickness of 1.5-2.5mm. During the cooling process, the polyolefin molecular chains in LSZH crystallize and solidify, forming a dense barrier layer. At the same time, the flame retardants in LSZH (such as aluminum hydroxide and magnesium hydroxide) are uniformly distributed in the polymer matrix, giving the material flame-retardant and low-smoke properties.

[0055] It is known that step S4 uses a glass fiber composite aluminum foil tape as a buffer layer. The low thermal conductivity of the glass fiber cloth delays the transfer of heat from the subsequent sheath extrusion to the internal refractory layer. The high reflectivity of the aluminum foil reflects radiant heat. Together, they reduce the temperature experienced by the methyl vinyl silicone rubber raw rubber in the carrier tape during sheath extrusion from 170-180℃ to about 100-120℃, thus avoiding thermal deformation. The sheath of LSZH is extruded using a semi-extrusion die. The extrusion pressure of 1-3MPa is significantly lower than that of an extrusion die. Combined with the pressure-resistant effect of the buffer layer, it ensures that the composite tape and composite paper in the irradiated cross-linked cable core do not experience thickness reduction or eccentricity during the extrusion process. Segmented water tank cooling is used to avoid rapid cooling that could cause internal stress and surface cracking in the sheath, while also preventing sudden cooling contraction from compressing the internal cable core. Under the action of step S4, while protecting the irradiated cross-linked cable core from heat damage caused by sheath extrusion, a sheath with mechanical protection, flame retardancy, low smoke, and non-toxicity is formed, so that the cable meets the requirements for laying and use and fire safety requirements. At the same time, the aluminum foil in the buffer layer can also serve as an electromagnetic shielding layer and an oxygen barrier layer, delaying the diffusion of oxygen to the fire-resistant layer in the event of a fire.

[0056] Understandably, in traditional solutions, if the inner refractory material is not fully cross-linked or pre-sintered, it is prone to softening and deformation under the high temperature and pressure of the sheath extrusion, leading to uneven or eccentric refractory layer thickness, severely affecting refractory performance. If a low-temperature extrusion process is used, special low-temperature processing sheath materials are required, resulting in high costs and limited choices. Step S4, by introducing a buffer layer wrapping process, effectively isolates the impact of heat and pressure on the inner refractory layer without changing the conventional LSZH sheath extrusion temperature. Specifically, after deep irradiation cross-linking, the carrier strip has a gel content exceeding 85%, exhibiting thermosetting properties and not melting or flowing at 170-180℃, although its elastic modulus still decreases by approximately 30-50%. The glass fiber cloth layer of the buffer layer utilizes its low thermal conductivity to slow down the rate of heat conduction to the carrier strip, reducing the maximum actual temperature the carrier strip experiences during sheath extrusion to approximately 100-120℃, and decreasing the modulus decrease to 10-20%, thus preventing deformation. Meanwhile, the composite paper is an inorganic material, and its performance remains stable and unaffected at 170-180℃. Therefore, the buffer layer in step S4 enables the integrated fire-resistant layer (composite tape and composite paper) formed in step S to maintain its structural integrity during subsequent processing, ultimately achieving both the cable's processability at room temperature and its fire resistance in a fire.

[0057] It is worth noting that the wrapping speed of the glass fiber composite aluminum foil tape is 10-20 m / min, matching the output speed of the cross-linked cable core irradiated in step S3. Too low a speed will reduce production efficiency, while too high a speed may cause tension fluctuations that could damage the buffer layer or the load-bearing strip. An overlap rate of 15-20% ensures continuous coverage of the buffer layer; below 15% may result in gaps, and above 20% will cause excessive material overlap, increasing the outer diameter. Tension <3N is based on the tensile strength of the glass fiber composite aluminum foil tape and the functional requirement that the buffer layer only needs to lightly adhere to the cable core surface. The sheath extrusion temperature of LSZH is 140-180℃, consistent with the melt processing window of conventional LSZH materials, ensuring that the LSZH material is fully plasticized and does not decompose. If the extruder temperature is below 140℃, plasticization will be poor, resulting in a rough sheath surface; above 180℃, the flame retardant may decompose, reducing flame retardant performance. The buffer layer wrapped around the cable core at 80-100℃ removes surface moisture and improves sheath adhesion. If the preheating temperature is too low, the sheath and buffer layer will not bond firmly; if it is too high, the aluminum foil in the buffer layer may oxidize. In segmented water cooling, the initial cooling at 40-50℃ allows the sheath to slowly set and reduces internal stress; the second cooling at 20-30℃ completely cools the sheath to room temperature. If a single low-temperature water tank is used for rapid cooling, cracks are likely to appear on the sheath surface, and the sudden cooling contraction may compress the internal fire-resistant layer, causing micro-cracks at the interface. The precise matching of these parameters ensures the reliability of the final cable's dimensional accuracy, mechanical integrity, and fire resistance.

[0058] The present invention also provides an ultra-high temperature fireproof cable based on aerogel composite ceramic fiber, which is obtained by the above-described preparation method.

[0059] Example 1: Step S1: Weigh out 100 parts by weight of methyl vinyl silicone rubber raw rubber, 40 parts by weight of fumed silica, and 4 parts by weight of hydroxyl silicone oil, and add them to a mixer. Mix at 110°C for 45 minutes to obtain a mixed rubber. Cool the mixed rubber to 35°C, add 50 parts by weight of mica powder, 40 parts by weight of wollastonite, 25 parts by weight of low-melting-point borosilicate glass powder, 1.5 parts by weight of silane coupling agent KH-550, 1.2 parts by weight of triallyl isocyanurate, and 0.35 parts by weight of dicumyl peroxide. Continue mixing for 40 minutes to obtain a compound. Pass the compound through a two-roll mill 6 times, and then calender it into a 0.5 mm thick roll at a three-roll calender at a roll temperature of 50°C. Place the roll in a hot air vulcanizing chamber at 165°C for 45 seconds, and then cool it to room temperature to obtain a carrying belt with a tensile strength of 3.4 MPa and an unreacted vinyl retention rate of 85%. The carrier belt is unwound, and molten methyl vinyl silicone rubber raw material at a temperature of 90°C is coated onto the surface of the carrier belt through a hot melt coating head. The wet film thickness is 0.12 mm. After being cooled and shaped by a cooling roller, an interface layer with a thickness of 0.08 mm is formed, resulting in a composite belt with a thickness of 0.58 mm.

[0060] Step S2: Alumina silicate ceramic fibers with a diameter of 4 μm and a length of 7 mm were dispersed in water to prepare a fiber slurry with a concentration of 0.8%. Polyacrylamide was added as a retention aid at a concentration of 0.08% of the dry weight of the fibers. Silica aerogel powder with a particle size of 30 μm and low-melting-point borosilicate glass powder were mixed with water at a mass percentage ratio of 60%, 25%, and 10% to prepare a filler slurry. This filler slurry was then stirred with the fiber slurry for 8 minutes to obtain a mixed slurry. The mixed slurry was vacuum-formed into a wet paper web using a slanted wire forming machine. After pressing and dewatering, the paper was dried at 130°C and then needle-punched at a density of 100 needles / cm. 2 Needle-punching reinforcement was performed at a depth of 6.5 mm to obtain a needle-punched reinforced paper web. The needle-punched reinforced paper web was then passed through an impregnation tank containing a 45% solids content polyacrylate emulsion, controlled by squeeze rollers, and dried at 130°C to achieve a polyacrylate binder content of 4%, resulting in an aerogel composite ceramic fiber paper with a thickness of 0.8 mm, a tensile strength of 1.8 MPa, and a dust loss rate of 0.8%. A 0.8% concentration of silane coupling agent KH-550 solution was sprayed onto the surface of the fiber paper, and dried under hot air at 90°C for 15 seconds to form a 5 μm thick reaction layer, thus obtaining the composite paper.

[0061] Step S3: Composite tape and composite paper were sequentially wrapped around a 10mm diameter cable core already insulated with mica tape at a wrapping speed of 12m / min. The wrapping tension was controlled at 4N, with a composite tape overlap rate of 28% and a composite paper overlap rate of 28%. The two were wrapped with a staggered seam width of 1, and the interface layer of the composite tape faced outward and the reaction layer of the composite paper faced inward in close contact, resulting in a wrapped cable core. The wrapped cable core was then sent into an electron beam irradiation chamber and rotated. Irradiation was carried out under conditions of 1.8MeV electron energy, 30mA beam current intensity, and 120kGy irradiation dose at a linear velocity of 12m / min. After irradiation, the core was cooled to room temperature, resulting in an irradiated cross-linked cable core with a 90° peel strength of 2.3N / mm.

[0062] Step S4: A 0.18mm thick glass fiber composite aluminum foil strip is wrapped around the surface of an irradiated cross-linked cable core at a wrapping speed of 15m / min, an overlap rate of 18%, and a tension of 2N, with the aluminum foil side facing outwards, resulting in a buffer-layer-wrapped cable core. Low-smoke halogen-free flame-retardant polyolefin granules are added to an extruder, with the feeding section temperature set at 150℃, the plasticizing section temperature at 165℃, the homogenizing section temperature at 175℃, and the die head temperature at 175℃, to melt and plasticize the material. The melt is then extruded through a semi-extrusion die at an extrusion pressure of 2MPa, coating the surface of the preheated (90℃) buffer-layer-wrapped cable core, resulting in a sheath thickness of 2.0mm. The wrapped cable is then subjected to segmented cooling in a water bath at 45℃ and a water bath at 25℃ to obtain an ultra-high temperature fire-resistant cable.

[0063] Example 2: The basic content is the same as in Example 1, except that: In step S1, the amount of dicumyl peroxide is 0.5 parts, the temperature of the hot air vulcanizing box is 170℃, the residence time is 35s, the tensile strength of the bearing belt is 4.0MPa, the unreacted vinyl retention rate is 82%, the interface layer thickness is 0.10mm, and the total thickness of the composite belt is 0.60mm.

[0064] In step S2, the polyacrylate binder content is 5%, the aerogel composite ceramic fiber paper thickness is 1.0 mm, the silane coupling agent KH-550 solution concentration is 1.0%, and the reaction layer thickness is 5 μm.

[0065] In step S3, the irradiation dose is 150 kGy, the electron energy is 2.0 MeV, and the 90° peel strength at the interface is 2.5 N / mm.

[0066] In step S4, the sheath thickness is 2.5 mm.

[0067] Example 3: The basic content is the same as in Example 1, except that: In step S1, the amount of dicumyl peroxide is 0.25 parts, the temperature of the hot air vulcanizing box is 160℃, the residence time is 55s, the tensile strength of the bearing belt is 3.1MPa, the unreacted vinyl retention rate is 88%, the interface layer thickness is 0.06mm, and the total thickness of the composite belt is 0.56mm.

[0068] In step S2, the polyacrylate binder content is 3.5%, the aerogel composite ceramic fiber paper thickness is 0.7 mm, the silane coupling agent KH-550 solution concentration is 0.6%, and the reaction layer thickness is 5 μm.

[0069] In step S3, the irradiation dose is 110 kGy, the electron energy is 1.6 MeV, and the 90° peel strength at the interface is 2.1 N / mm.

[0070] In step S4, the sheath thickness is 1.8 mm.

[0071] Comparative Example 1 The difference from Example 1 is as follows: In step S1, no dicumyl peroxide is added, no thermal initiator is added to the compound, no hot air vulcanization is performed after calendering, the carrier belt is not lightly pre-crosslinked, its tensile strength is 1.2 MPa, and the unreacted vinyl retention rate is 100%; no interface layer is coated, no hot melt coating process is performed, and the composite belt is only a single layer of uncrosslinked silicone rubber.

[0072] In step S2, during the preparation of aerogel composite ceramic fiber paper, the needle-punched reinforced paper web is not impregnated with polyacrylate emulsion, and is not reinforced with adhesive. The tensile strength of the paper web is 0.6 MPa and the dust loss rate is 4.5%. It is not sprayed with silane coupling agent KH-550, and there is no reaction layer. The composite paper is just untreated ceramic fiber paper.

[0073] In step S3, the composite tape directly contacts the composite paper during wrapping, without chemical bonding between the interface layer and the reaction layer; no electron beam irradiation treatment is performed, and the tape proceeds directly to the next step after wrapping without irradiation crosslinking process. The composite tape remains in an uncrosslinked state, and the inner layer has no crosslinked structure.

[0074] In step S4, the fiberglass composite aluminum foil tape without a buffer layer is used as a buffer layer, and the cross-linked cable core is directly extruded for sheathing. The sheathing extrusion temperature and parameters are the same as in Example 1, but because there is no buffer layer for heat insulation and the composite tape is not cross-linked, the composite tape softens and deforms during sheathing extrusion, and the thickness of the fire-resistant layer is uneven.

[0075] The following is a comparison of the data from Examples 1, 2, and 3 with Comparative Example 1. Please refer to Table 1 for details: Table 1 In Table 1, the tensile strength of the bearing strip is tested according to GB / T 528 standard using a universal testing machine with a sample width of 10 mm, a gauge length of 50 mm, and a tensile speed of 500 mm / min. The tensile strength of the composite paper is tested using the same method as the bearing strip. For the composite paper dusting rate, a certain mass of sample is weighed, repeatedly bent 100 times on a bending tester, and the mass of the detached powder is weighed to calculate the mass loss rate. The 90° peel strength test is conducted according to GB / T 2790 standard, peeling the composite strip and composite paper layers at a peeling speed of 50 mm / min, and recording the average force during the peeling process. The minimum bending radius of the cable is tested according to GB / T 12706.1 standard, repeatedly bending the cable at room temperature until cracks appear in the outer sheath or internal structural damage occurs, and recording the ratio of the bending radius to the cable's outer diameter at this point. The fire resistance test for line integrity is conducted according to GB / T 19216.21 standard, applying the rated voltage to the cable under a 950℃ flame, continuously monitoring the line continuity, and recording the time the line remains intact. The thermal conductivity of the composite layer was tested at room temperature using a heat flow method tester according to ASTM C518 standard.

[0076] A comparison of the test data from Examples 1, 2, and 3 with Comparative Example 1 shows that the preparation method proposed in this invention is significantly superior to the traditional process represented by Comparative Example 1 in several key technical indicators. Regarding the tensile strength of the carrier belt, the tensile strengths of the carrier belts in Examples 1-3 are 3.4 MPa, 4.0 MPa, and 3.1 MPa, respectively, while that in Comparative Example 1 is only 1.2 MPa. This is because Comparative Example 1 did not undergo mild pre-crosslinking treatment, resulting in insufficient carrier belt strength, which easily leads to tensile deformation during the wrapping process. In contrast, this invention, by adding dicumyl peroxide and performing hot air vulcanization, enables the carrier belt to achieve a tensile strength greater than 3 MPa to meet the wrapping tension requirements, while retaining more than 80% of unreacted vinyl groups for subsequent irradiation crosslinking. In terms of tensile strength and dust loss rate of composite paper, the tensile strength of composite paper in Examples 1-3 is 1.8 MPa, 2.0 MPa and 1.6 MPa, respectively, and the dust loss rate is 0.8%, 0.6% and 0.9%, respectively. However, the tensile strength of composite paper in Comparative Example 1 is only 0.6 MPa and the dust loss rate is as high as 4.5%. This is because Comparative Example 1 did not use polyacrylate binder impregnation for reinforcement, while the present invention adopts a process sequence of needle punching followed by impregnation, which enables the composite paper to obtain sufficient processing strength and achieve a dust loss rate of less than 1%.

[0077] Regarding the 90° peel strength at the interface, the peel strengths of Examples 1-3 were 2.3 N / mm, 2.5 N / mm, and 2.1 N / mm, respectively, while Comparative Example 1 was only 0.4 N / mm. This is because Comparative Example 1 did not have an interface layer coated, did not undergo coupling agent treatment, and did not undergo overall irradiation crosslinking. In contrast, this invention uses hot-melt coating of the interface layer, spraying of silane coupling agent KH-550 to form a reaction layer, and overall electron beam irradiation after wrapping to achieve deep co-crosslinking between the interface layer and the composite tape, and chemical bridging with the reaction layer, transforming physical contact into permanent chemical bonding, ensuring that the cable will not experience interlayer peeling under bending and fire thermal stress. Regarding the minimum bending radius of the cable, the minimum bending radius of Examples 1-3 was 6 times the cable outer diameter, while that of Comparative Examples 1-12 times the cable outer diameter. This is because Comparative Example 1 used pre-sintered ceramic fiber tape, which made the material brittle and hard. In contrast, this invention eliminates the pre-sintering process, and both the composite tape and composite paper are in a flexible state during wrapping, fundamentally avoiding the brittle fracture problem caused by pre-sintering.

[0078] From the perspective of the integrity time of the fire resistance test circuit, Examples 1-3 all maintained circuit integrity for more than 180 minutes under a flame at 950℃, while Comparative Example 1 only maintained it for about 60 minutes before failing. The reason for the failure was that the flame penetrated through the overlap seam of the wrapping and the interlayer peeling caused the fire-resistant layer to crack. This invention uses light pre-crosslinking and overall irradiation to form a highly crosslinked thermosetting structure in the composite tape. The low-melting-point borosilicate glass powder in the composite paper melts at high temperature to promote fiber sintering into a shell, and the silica aerogel powder provides an extremely low thermal conductivity. The buffer layer protects the fire-resistant layer from heat damage during sheath extrusion and further delays heat conduction in a fire, together achieving a significant improvement in fire resistance performance. From the perspective of the thermal conductivity of the composite layer, the thermal conductivity of Examples 1-3 are 0.032 W / m·K, 0.031 W / m·K and 0.033 W / m·K respectively, all of which are lower than 0.045 W / m·K of Comparative Example 1. This is due to the fact that the present invention introduces 20-30% silica aerogel powder into the composite paper and physically anchors it in the fiber network through a needle punching process.

[0079] In summary, this invention improves structural stability during the processing stage and the initial stage of fire heating through light pre-crosslinking of the bearing belt and overall deep irradiation, composite reinforcement of composite paper needle punching and low-content binder, and the formation of a continuous ceramic shell in the inorganic system of the composite paper at high temperature. It systematically solves the contradiction between pre-ceramicization treatment and flexibility, and achieves the unity of room temperature processing flexibility, structural integrity and ultra-high temperature fire resistance.

[0080] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ultra-high temperature fireproof cables based on aerogel composite ceramic fibers, characterized in that, The preparation method includes the following steps: Step S1: Prepare a compound rubber containing a radiation sensitizer and a thermal initiator, and calender and pre-crosslink it to obtain a carrier belt. Then, coat the carrier belt with a radiation-crosslinkable silicone rubber to obtain a composite belt with an interface layer. Step S2: Prepare a mixed slurry and convert it into a fiber paper substrate. Then, impregnate the fiber paper substrate to obtain aerogel composite ceramic fiber paper. Subsequently, form a reaction layer on the aerogel composite ceramic fiber paper to obtain composite paper. Step S3: Wrap the composite tape and composite paper around the cable core, and then perform irradiation treatment. After the treatment is completed, an irradiated cross-linked cable core is obtained. Step S4: Wrap a buffer material around the irradiated cross-linked cable core to obtain a buffer layer wrapped around the cable core, and then form a sheath on the buffer layer wrapped around the cable core by extrusion molding to obtain an ultra-high temperature fireproof cable.

2. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 1, characterized in that, Step S1 specifically includes the following steps: Step S11: Mix methyl vinyl silicone rubber raw rubber, fumed silica and hydroxyl silicone oil at 100-120℃ for 30-60 min to obtain a mixed rubber; then add additives containing TAIC and DCP to the mixed rubber and mix at ≤40℃ for 30-60 min to obtain a compounded rubber. Step S12: After degassing the compound, roll it at a roller temperature of 40-60℃ to obtain a roll material; then pass the roll material through a hot air vulcanizing box at a temperature of 160-170℃ within 30-60 seconds. After passing through, the roll material is cooled to room temperature to obtain a carrier belt. Step S13: Apply molten methyl vinyl silicone rubber raw material at 80-100℃ onto the carrier belt, and then cool it to obtain a composite belt with an interface layer formed on the carrier belt.

3. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 2, characterized in that, In step S11, the additives further include mica powder, wollastonite, low-melting-point borosilicate glass powder, and silane coupling agent KH-550; by mass parts, the methyl vinyl silicone rubber raw rubber is 100 parts, the fumed silica is 35-45 parts, the hydroxyl silicone oil is 3-5 parts, the TAIC is 0.8-1.5 parts, the DCP is 0.2-0.5 parts, the mica powder is 40-60 parts, the wollastonite is 30-50 parts, the low-melting-point borosilicate glass powder is 20-30 parts, and the silane coupling agent KH-550 is 1-2 parts; the specific surface area of ​​the fumed silica is 200-300 m². 2 / g, the viscosity of the hydroxyl silicone oil is 20-50cSt, the particle size of the mica powder is 10-20μm, the particle size of the wollastonite is 5-15μm, and the softening point of the low melting point borosilicate glass powder is 480-520℃ and the particle size D50 is 5-10μm. In step S12, the thickness of the roll material is 0.4-0.6 mm; the gel content of the carrier tape is 10-20%, the tensile strength is >3 MPa, and more than 80% of unreacted vinyl groups are retained. In step S13, the thickness of the interface layer is 0.05-0.10 mm, and the thickness of the composite strip is 0.45-0.70 mm.

4. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 3, characterized in that, Step S2 specifically includes the following steps: Step S21: Mix aluminosilicate ceramic fiber, polyacrylamide, and water to obtain fiber slurry; mix silica aerogel powder and low-melting-point borosilicate glass powder with water to obtain filler slurry; then stir the filler slurry and fiber slurry for 5-10 minutes to obtain mixed slurry; vacuum suction and press dewater the mixed slurry to obtain wet paper web; then dry the wet paper web at 120-150℃ to obtain dry paper web; subsequently, needle punch the dry paper web to obtain needle-punched reinforced paper web. Step S22: After passing the needle-punched reinforced paper web through the impregnation tank, the needle-punched reinforced paper web is squeezed dry using a squeeze roller, and then dried at a temperature of 120-150℃ to obtain aerogel composite ceramic fiber paper. Step S23: Spray the silane coupling agent KH-550 solution onto the aerogel composite ceramic fiber paper and dry it under hot air at 80-100℃ for 10-20s to obtain a composite paper with a reaction layer formed on the aerogel composite ceramic fiber paper.

5. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 4, characterized in that, In step S21, by mass percentage, the aluminosilicate ceramic fiber comprises 55-65%, the silica aerogel powder comprises 20-30%, the low-melting-point borosilicate glass powder comprises 8-12%, and the polyacrylamide comprises 0.05-0.1% of the dry weight of the aluminosilicate ceramic fiber; the aluminosilicate ceramic fiber has a diameter of 3-5 μm and a length of 5-10 mm, the silica aerogel powder has a particle size of 10-50 μm, and the low-melting-point borosilicate glass powder is the same as that in step S11; the needle punching density is 80-120 needles / cm. 2 The depth is 5-8mm; In step S22, the impregnation tank is filled with a polyacrylate emulsion with a solid content of 40-50%, the polyacrylate binder content in the needle-punched reinforced paper web after squeezing is 3-5 wt%, and the thickness of the aerogel composite ceramic fiber paper is 0.6-1.0 mm. In step S23, the concentration of the silane coupling agent KH-550 solution is 0.5-1.0 wt%, and the thickness of the reaction layer is 5 μm.

6. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 5, characterized in that, Step S3 specifically includes the following steps: Step S31: Wrap the composite tape and composite paper onto the cable core sequentially at a wrapping speed of 10-15 m / min to obtain a wrapped cable core; Step S32: Rotate the wrapped cable core in the electron beam irradiation chamber, and cool it to room temperature after irradiation to obtain the irradiated cross-linked cable core.

7. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 6, characterized in that, In step S31, the overlap rate of the composite tape and the composite paper is 25-30%, the wrapping tension is <5N, and the interface layer and the reaction layer are in contact when the composite tape is wrapped. In step S32, the electron energy of the electron beam irradiation chamber is 1.5-2.0 MeV, the beam current intensity is 20-40 mA, the irradiation dose is 100-150 kGy, and the linear velocity is 10-15 m / min.

8. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 7, characterized in that, Step S4 specifically includes the following steps: Step S41: Wrap glass fiber composite aluminum foil tape around the irradiated cross-linked cable core to obtain a buffer layer wrapped cable core; Step S42: Add LSZH granules to an extruder to obtain a melt, and coat the cable core with a buffer layer at a temperature of 80-100℃. After cooling in a water tank, an ultra-high temperature fireproof cable with a buffer layer forming a sheath on the cable core is obtained.

9. The method for preparing ultra-high temperature fireproof cable based on aerogel composite ceramic fiber according to claim 8, characterized in that, In step S41, the wrapping speed of the glass fiber composite aluminum foil strip is 10-20 m / min, the overlap rate is 15-20%, the tension is <3N, and the thickness of the glass fiber composite aluminum foil strip is 0.15-0.20 mm. In step S42, the temperature of the extruder is 140-180℃, the water tank includes initial cooling at 40-50℃ and secondary cooling at 20-30℃, and the thickness of the sheath is 1.5-2.5mm.

10. An ultra-high temperature fireproof cable based on aerogel composite ceramic fiber, characterized in that, The ultra-high temperature fireproof cable based on aerogel composite ceramic fiber is obtained by the preparation method described in any one of claims 1-9.

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