Indoor cable wire fireproof insulating material and preparation method thereof

Abstract

The invention relates to the field of insulating materials, in particular to an indoor cable wire fireproof insulating material and a preparation method thereof.The insulating material comprises a basalt fiber woven layer, an interface layer and a mica tape layer which are sequentially arranged; the basalt fiber woven layer comprises three-dimensional basalt fiber skeleton cloth and nano silicon carbide loaded on the surface of the three-dimensional basalt fiber skeleton cloth; the mica tape layer comprises mica paper, high-thermal-conductivity slurry, intumescent flame-retardant slurry and ceramic precursor slurry. The interface layer is formed by compounding phase change microcapsules, thermal expansion monomers and low-melting-point glass powder, and in the high-temperature stage (300-500 DEG C) of the initial stage of a fire disaster, the thermal expansion monomers are rapidly polymerized and foamed to form an expansion thermal insulation layer; and under continuous flame firing (gt; 380 DEG C), the glass powder is softened and is co-melted with a matrix decomposition product, so that the formation of a compact ceramic protective layer is promoted. Namely, the interface layer can exert corresponding effects at different temperatures, so that the fireproof performance is improved.

Description

Technical Field

[0001] This invention relates to the field of insulating materials, and more specifically, to a fire-resistant insulating material for indoor cables and wires and its preparation method. Background Technology

[0002] The indoor cable systems of modern high-rise buildings, data centers, and smart homes not only require insulation materials to have basic flame-retardant and fire-resistant properties, but also place higher demands on current carrying capacity, heat dissipation, electromagnetic interference resistance, flexibility, and adaptive protection under fire conditions.

[0003] Traditional mica tape / glass fiber cloth composite structures are inorganic flame-retardant materials that do not release harmful gases during combustion. For example, patent CN119626629A discloses a synthetic mica tape for wire and cable production and its manufacturing method. This mica tape includes: glass fiber cloth; and a first adhesive, which is disposed on top of the glass fiber cloth. Flame-retardant mica paper is obtained by immersing mica paper in a treatment solution composed of organosilicone, nano-ceramic powder, nano-silica, and a silane coupling agent, followed by drying. This flame-retardant mica paper exhibits a single flame-retardant property. Summary of the Invention

[0004] The purpose of this invention is to provide a fireproof insulation material for indoor cables and wires, in which the interface layer can perform corresponding functions at different temperatures to improve fire resistance.

[0005] Another objective of this invention is to provide a method for preparing fire-resistant insulation materials for indoor cables and wires. This method utilizes a multi-stage slit coating technique to precisely control the thickness and composition of each functional layer; segmented curing ensures sufficient reaction and interfacial fusion of different chemical systems. This results in more complete bonding and higher bonding strength between the layers.

[0006] The technical problem solved by this invention is achieved by the following technical solution.

[0007] On one hand, embodiments of the present invention provide a fireproof insulation material for indoor cables and wires, the insulation material comprising a basalt fiber braided layer, an interface layer, and a mica tape layer arranged sequentially; The interface layer, by weight, comprises the following raw materials: 8-12 parts of phosphorus-containing acrylate monomer, 12-30 parts of hydroxyethyl acrylate, 20-30 parts of acrylate prepolymer, 20-40 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of phase change microcapsules, 5-10 parts of glass powder, 0.1-0.6 parts of dibutyltin dilaurate, and 1-3.2 parts of tetraethyl orthosilicate; The basalt fiber woven layer includes: a three-dimensional basalt fiber skeleton fabric and nano-silicon carbide loaded on the surface of the three-dimensional basalt fiber skeleton fabric; The mica tape layer includes: mica paper, high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry.

[0008] In some embodiments of the present invention, the high thermal conductivity slurry comprises, by weight, 100 parts of polyimide precursor, 5-15 parts of carboxylated multi-walled carbon nanotubes, 10-30 parts of aluminum nitride powder, and 0.5-2 parts of dispersant.

[0009] In some embodiments of the present invention, the intumescent flame retardant slurry comprises, by weight, 100 parts of water-based acrylate binder, 20-30 parts of ammonium polyphosphate, 8-12 parts of pentaerythritol, 6-10 parts of melamine, 3-8 parts of tin phosphide, and 1-3 parts of ammonium molybdate.

[0010] In some embodiments of the present invention, the ceramic precursor slurry comprises, by weight, 100 parts of methyltrimethoxysilane, 10-20 parts of zirconium dioxide, 5-10 parts of zinc borate, 2-5 parts of acetic acid, and 200-300 parts of solvent.

[0011] In some embodiments of the present invention, the wall material of the phase change microcapsule is silicon dioxide and the core material is paraffin wax.

[0012] In some embodiments of the present invention, the softening point of the glass powder is less than 380°C.

[0013] On the other hand, embodiments of the present invention provide a method for preparing the above-mentioned fire-resistant insulation material for indoor cables and wires, comprising the following steps: S1, γ-aminopropyltriethoxysilane and anhydrous ethanol are mixed at a volume ratio of 1:9, hydrolyzed, and then nano-silicon carbide powder is added and ultrasonically dispersed to obtain a sol; three-dimensional basalt fiber skeleton fabric is passed through a sol tank containing the sol at a speed of 1-3 m / min for impregnation treatment; and dried in an oven at 80-120℃ to obtain a basalt fiber woven layer. S2, prepare high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry respectively; let the mica paper base tape pass through a multi-stage slit coating device in sequence, apply high thermal conductivity slurry at the first slit coating head, dry and simultaneously apply a magnetic field, and cure to obtain a thermally conductive layer; then pass through the second slit coating head to apply intermediate layer slurry, dry to obtain intumescent layer; then pass through the third slit coating head to apply ceramic precursor slurry, and cure to obtain ceramic precursor layer; wind up and age to obtain mica tape layer. S3, phosphorus-containing acrylate monomers, hydroxyethyl acrylate, and a portion of acrylate prepolymer are mixed to obtain the matrix phase; In the matrix phase, phase change microcapsules and glass powder with surface treated with silane coupling agent are added and stirred to disperse evenly; Then add hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate and tetraethyl orthosilicate, and stir under vacuum to obtain the interface layer slurry; S4. Unfold the basalt fiber braided layer, coat one side with an interface layer slurry, attach the uncoated side of the mica tape layer to the interface layer slurry, and roll it to obtain a wet preform. The wet preform is cured in sections, naturally cooled to room temperature, rolled up, and cut to obtain the insulating material.

[0014] In some embodiments of the present invention, the segmented curing includes: First stage: Curing at 80-90℃ for 5-8 minutes; Second stage: Curing at 120-130℃ for 15-20 minutes; Third stage: Curing at 180-200℃ for 5-8 minutes.

[0015] In some embodiments of the present invention, in S2, the thickness of the cured thermally conductive layer is 20-50 g / m. 2 The thickness of the expansion layer is 40-80 g / m. 2 The thickness of the ceramic precursor layer is 30-60 g / m. 2 .

[0016] In some embodiments of the present invention, in step S3, the mass ratio of the matrix phase and the hydroxyl-terminated polydimethylsiloxane is (1.5-2.5):1.

[0017] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: The insulating material provided by this invention has an interface layer composed of phase change microcapsules, thermally expanding monomers, and low-melting-point glass powder. During the conductor overload heating stage (≈65℃), the core material in the phase change microcapsules undergoes a phase change, absorbing heat and delaying the temperature rise of the insulation system. In the initial high-temperature stage of a fire (300-500℃), the expanding monomers rapidly polymerize and foam, forming an expanding heat-insulating layer. Under continuous flame burning (>380℃), the glass powder softens and co-melts with the matrix decomposition products, promoting the formation of a dense ceramic protective layer. In other words, the interface layer can exert corresponding effects at different temperatures, improving fire resistance.

[0018] Within the mica tape layer, carbon nanotubes and aluminum nitride fillers, oriented and aligned by a magnetic field, form a thermally conductive network. This facilitates rapid heat dissipation from the conductor under normal conditions, allowing the cable to carry higher currents with the same insulation thickness. Simultaneously, the internal expansion layer and ceramic precursor layer form a high-porosity expanded carbon layer and a dense ceramic layer at different stages of a fire, respectively, providing excellent high-temperature insulation barrier performance and effectively delaying heat transfer towards the conductor.

[0019] Using a three-dimensional basalt fiber braided layer with a surface modified by nano-silicon carbide as a reinforcing skeleton improves the tensile strength and tear resistance of the insulation material, while its three-dimensional interpenetrating structure effectively suppresses the tendency of interlayer delamination. The corrosion resistance and water repellency of basalt fiber itself enable this composite material to maintain stable performance in complex indoor environments such as humid and chemical media, thus extending the service life of the cable.

[0020] The preparation method provided in this invention uses a multi-level slit coating technique to precisely control the thickness and composition of each functional layer; segmented curing ensures sufficient reaction and interfacial fusion of different chemical systems. This results in more complete bonding and higher bonding strength between the layers. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0023] On one hand, embodiments of the present invention provide a fireproof insulation material for indoor cables and wires, the insulation material comprising a basalt fiber braided layer, an interface layer, and a mica tape layer arranged sequentially; The interface layer comprises, by weight, the following raw materials: 8-12 parts of phosphorus-containing acrylate monomer, 12-30 parts of hydroxyethyl acrylate, 20-30 parts of acrylate prepolymer, 20-40 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of phase change microcapsules, 5-10 parts of glass powder, 0.1-0.6 parts of dibutyltin dilaurate, and 1-3.2 parts of tetraethyl orthosilicate; wherein the wall material of the phase change microcapsules is silicon dioxide, and the core material is paraffin wax.

[0024] The basalt fiber woven layer includes: a three-dimensional basalt fiber skeleton fabric and nano-silicon carbide loaded on the surface of the three-dimensional basalt fiber skeleton fabric; The mica tape layer includes: mica paper, high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry.

[0025] In some embodiments of the present invention, the high thermal conductivity slurry comprises, by weight, 100 parts of polyimide precursor, 5-15 parts of carboxylated multi-walled carbon nanotubes, 10-30 parts of aluminum nitride powder, and 0.5-2 parts of dispersant.

[0026] In some embodiments of the present invention, the intumescent flame retardant slurry comprises, by weight, 100 parts of water-based acrylate binder, 20-30 parts of ammonium polyphosphate, 8-12 parts of pentaerythritol, 6-10 parts of melamine, 3-8 parts of tin phosphide, and 1-3 parts of ammonium molybdate.

[0027] In some embodiments of the present invention, the ceramic precursor slurry comprises, by weight, 100 parts of methyltrimethoxysilane, 10-20 parts of zirconium dioxide, 5-10 parts of zinc borate, 2-5 parts of acetic acid, and 200-300 parts of solvent.

[0028] In some embodiments of the present invention, the wall material of the phase change microcapsule is silicon dioxide and the core material is paraffin wax.

[0029] In some embodiments of the present invention, the softening point of the glass powder is less than 380°C.

[0030] On the other hand, embodiments of the present invention provide a method for preparing the above-mentioned fire-resistant insulation material for indoor cables and wires, comprising the following steps: S1, γ-aminopropyltriethoxysilane and anhydrous ethanol are mixed at a volume ratio of 1:9, hydrolyzed, and then nano-silicon carbide powder is added and ultrasonically dispersed to obtain a sol; three-dimensional basalt fiber skeleton fabric is passed through a sol tank containing the sol at a speed of 1-3 m / min for impregnation treatment; and dried in an oven at 80-120℃ to obtain a basalt fiber woven layer. S2, prepare high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry respectively; let the mica paper base tape pass through a multi-stage slit coating device in sequence, apply high thermal conductivity slurry at the first slit coating head, dry and simultaneously apply a magnetic field, and cure to obtain a thermally conductive layer; then pass through the second slit coating head to apply intermediate layer slurry, dry to obtain intumescent layer; then pass through the third slit coating head to apply ceramic precursor slurry, and cure to obtain ceramic precursor layer; wind up and age to obtain mica tape layer. The inner layer high thermal conductivity slurry is made by dispersing carboxylated multi-walled carbon nanotubes (aspect ratio > 1000) and nano-aluminum nitride in N-methylpyrrolidone at a mass ratio of 1:2, adding polyimide precursor resin as a binder, and stirring until homogeneous.

[0031] Intermediate high flame retardant expansion layer slurry: Ammonium polyphosphate, pentaerythritol, melamine and tin phosphide (particle size 1-5μm) are dispersed in deionized water at a mass ratio of 20:8:6:3, and water-based acrylic binder is added and stirred evenly.

[0032] Outer ceramic precursor slurry: Methyltrimethoxysilane, nano-zirconium dioxide, and zinc borate are dispersed in an ethanol / water mixed solvent at a mass ratio of 100:15:5, and hydrolyzed to a certain viscosity using acetic acid as a catalyst.

[0033] S3, phosphorus-containing acrylate monomers, hydroxyethyl acrylate, and a portion of acrylate prepolymer are mixed to obtain the matrix phase; In the matrix phase, phase change microcapsules and glass powder with surface treated with silane coupling agent are added and stirred to disperse evenly; Then add hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate and tetraethyl orthosilicate, and stir under vacuum to obtain the interface layer slurry; S4. Unfold the basalt fiber braided layer, coat one side with an interface layer slurry with a coating thickness of 100-300μm, attach the uncoated side of the mica tape layer to the interface layer slurry, and roll it to obtain a wet preform. The wet preform is cured in sections, naturally cooled to room temperature, rolled up, and cut to obtain the insulating material.

[0034] In some embodiments of the present invention, the segmented curing includes: First stage: Curing at 80-90℃ for 5-8 minutes; Second stage: Curing at 120-130℃ for 15-20 minutes; Third stage: Curing at 180-200℃ for 5-8 minutes.

[0035] In some embodiments of the present invention, in S2, the thickness of the cured thermally conductive layer is 20-50 g / m. 2 The thickness of the expansion layer is 40-80 g / m. 2 The thickness of the ceramic precursor layer is 30-60 g / m. 2 .

[0036] In some embodiments of the present invention, in step S3, the mass ratio of the matrix phase and the hydroxyl-terminated polydimethylsiloxane is (1.5-2.5):1.

[0037] In some embodiments of the present invention, the strength of the applied magnetic field is 0.5T-0.8T.

[0038] The features and performance of the present invention will be further described in detail below with reference to embodiments. Example 1 1. Raw materials and formula Interface layer: 10 parts of phosphorus-containing acrylate monomer (PETA-P, pentaerythritol triacrylate phosphate, obtained by phosphorylation of pentaerythritol triacrylate), 20 parts of hydroxyethyl acrylate (HEA, CAS No. 818-61-1), 25 parts of polyurethane acrylate prepolymer (Shenzhen Guanghua Weiye Co., Ltd., ePUA-Bio005H), 30 parts of hydroxyl-terminated polydimethylsiloxane (HTPDMS, 1000cP, Wuhan Jiehong International Trade Co., Ltd.), 15 parts of phase change microcapsules (65℃), 8 parts of low melting point borosilicate glass powder (softening point 380℃), 0.15 parts of dibutyltin dilaurate, and 1.5 parts of tetraethyl orthosilicate.

[0039] Basalt fiber woven layer: 200tex basalt fiber three-dimensional plain weave fabric (area density 280g / m²). Surface treatment sol: KH-550 to nano-silicon carbide (40nm) mass ratio 7:3, solid content 2%.

[0040] Gradient mica band layer: High thermal conductivity layer: 100 parts of polyimide precursor (Boya Poly (Zhoushan) Special Materials Co., Ltd., solid content 20%), 8 parts of carboxylated multi-walled carbon nanotubes (length ~15μm), 20 parts of aluminum nitride (particle size 3μm), and 1 part of PVP dispersant.

[0041] Intumescent flame retardant layer: 100 parts of waterborne acrylic emulsion (BASF, solid content 45%), 25 parts of ammonium polyphosphate (Type II), 10 parts of pentaerythritol, 8 parts of melamine, 5 parts of tin phosphide, and 2 parts of ammonium molybdate.

[0042] Ceramicized layer: 100 parts methyltrimethoxysilane, 15 parts nano-zirconium dioxide (30nm), 7 parts zinc borate (fire retardant grade), 3 parts acetic acid, and 250 parts ethanol / water = 2 / 1 mixed solvent.

[0043] 2. Preparation steps: Step S1: Preparation of basalt fiber braided layer Take 200tex alkali-free basalt fiber untwisted roving, set the warp density to 8 threads / cm and the weft density to 8 threads / cm on a three-dimensional orthogonal weaving machine, and weave it into a three-dimensional basalt fiber skeleton fabric with a thickness of 0.35mm and a surface density of 280g / m².

[0044] Surface treatment sol preparation: In a reactor, γ-aminopropyltriethoxysilane (KH-550) and anhydrous ethanol were mixed at a volume ratio of 1:9. Deionized water (1.5 times the molar volume of KH-550) was added dropwise while stirring, and the mixture was hydrolyzed at room temperature for 30 minutes. Nano-silicon carbide powder (particle size 40±5nm), with a mass of 30% of the KH-550 mass, was then added. The mixture was ultrasonically dispersed at 400W for 60 minutes to obtain a homogeneous sol with a solid content of 2.0wt%.

[0045] Impregnation and drying: The three-dimensional basalt fiber skeleton fabric is drawn through the sol impregnation tank at a speed of 2 m / min, and the impregnation time is controlled at 3 seconds. Then it enters a three-stage drying channel with the temperatures set at 80℃, 100℃ and 120℃ respectively, and the total drying time is 5 minutes, to obtain a basalt fiber woven layer with a Si-O-Si / KH-550 / nano silicon carbide hybrid coating on the surface, which is then wound up for later use.

[0046] Step S2: Preparation of Gradient Functional Mica Strip Layer Preparation of high thermal conductivity slurry: In a nitrogen-protected dispersion vessel, add 100 parts by weight of polyimide precursor solution (20% solids content, 4500 cP viscosity). While stirring at 600 rpm, slowly add 8 parts by weight of carboxylated multi-walled carbon nanotubes and 1 part by weight of PVPK30 sequentially. After the addition is complete, increase the stirring speed to 2000 rpm and disperse for 30 minutes. Finally, add 20 parts by weight of aluminum nitride powder and continue dispersing at 1500 rpm for 60 minutes. Pass the slurry through a 200-mesh sieve to obtain a uniform high thermal conductivity slurry.

[0047] Preparation of intumescent flame retardant slurry: In a high-speed disperser, add 100 parts by weight of aqueous acrylic emulsion (solid content 45%, Tg -10℃). Then, sequentially add 25 parts by weight of ammonium polyphosphate (Type II, degree of polymerization >1000), 10 parts by weight of pentaerythritol, 8 parts by weight of melamine, and 2 parts by weight of ammonium molybdate, and premix at 800 rpm for 10 minutes. Finally, add 5 parts by weight of tin phosphide and disperse at 1200 rpm for 40 minutes to obtain the intumescent flame retardant slurry.

[0048] Preparation of ceramic precursor slurry: 100 parts by weight of methyltrimethoxysilane were mixed with 250 parts by weight of an ethanol / water mixed solvent (volume ratio 2:1). Under an ice-water bath and stirring at 300 rpm, 3 parts by weight of a dilute solution of acetic acid catalyst were added dropwise. After hydrolysis for 2 hours, 15 parts by weight of nano-zirconia and 7 parts by weight of zinc borate were added, and the mixture was ultrasonically dispersed for 30 minutes to obtain the ceramic precursor slurry.

[0049] Multi-stage slot coating: The substrate is made of 0.06mm thick synthetic mica paper, and the machine operates at a speed of 1.5m / min.

[0050] First coating head: slit width 0.15mm, pressure 0.15MPa, coating with high thermal conductivity slurry. The coated wet film passes through a 120℃, 3-meter-long infrared drying zone, and a 0.5T magnetic field is applied in the infrared drying zone. The weight gain of the dry film (i.e., the thickness of the thermally conductive layer) is controlled at 30±2g / m².

[0051] Second coating head: On the already formed high thermal conductivity film, apply the intumescent flame retardant slurry in the same way, and dry the film through a 100℃ hot air drying zone, with the dry film weight gain controlled at 60±3g / m².

[0052] Third coating head: Ceramic precursor slurry is coated on the expanded film that has already formed, and it is initially gelled in an 80℃ low-temperature drying zone. The weight gain of the dry film is controlled at 45±2g / m².

[0053] Final curing and winding: The three-layer coated mica tape is introduced into a 280℃, 10-meter-long nitrogen-protected curing oven for 3 minutes to complete imidization and condensation of the ceramic precursor. After cooling to 50℃, it is aged in a constant temperature and humidity chamber (23℃, 50%RH) for 24 hours, and then wound up to obtain the gradient functional mica tape layer.

[0054] Step S3: Preparation of intelligent response interface layer slurry Matrix phase preparation: In a light-proof container, 5 parts by weight of pentaerythritol triacrylate phosphate, 20 parts by weight of hydroxyethyl acrylate and 25 parts by weight of polyurethane acrylate prepolymer (functionality 2) were mixed and stirred at 400 rpm until uniform and transparent.

[0055] Filler pre-dispersion: 15 parts by weight of phase change microcapsules (paraffin@SiO2, D50=10μm, phase change enthalpy 180J / g) and 8 parts by weight of low melting point glass powder (softening point 380℃, D50=5μm) were added to the above matrix phase. The mixture was dispersed at 5000rpm for 10 minutes using a high-speed shear emulsifier.

[0056] Final slurry preparation: Add 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (viscosity 1000 cP), 0.15 parts by weight of dibutyltin dilaurate, and 1.5 parts by weight of tetraethyl orthosilicate. Place the entire system in a planetary mixer and stir at 200 rpm for 15 minutes under a vacuum of -0.095 MPa to remove bubbles, obtaining an interface layer slurry with a viscosity of approximately 8500 cP.

[0057] Step S4: Lamination and Curing Coating and bonding: The basalt fiber braided layer is unfolded and run at a speed of 1 m / min. An interface layer slurry is uniformly coated onto its surface using a precision slot coater, with the wet film thickness controlled at 200 ± 10 μm using a laser thickness gauge. Immediately, the side of the mica tape layer without any slurry coating is aligned and bonded to the basalt fiber using a pair of rubber rollers (pressure 0.2 MPa, roller temperature 60℃) to form a wet three-layer preform.

[0058] Segmented curing: The preform is sent into a three-temperature zone curing oven.

[0059] First stage: 85±2℃, hot air circulation, stay for 8 minutes to complete the initial thermal polymerization of the acrylate system and form a preliminary network structure.

[0060] Second stage: 120±2℃, hot air circulation, stay for 20 minutes, the temperature rises, the activity of organotin catalyst is enhanced, tetraethyl orthosilicate and hydroxyl-terminated PDMS undergo condensation crosslinking, releasing ethanol.

[0061] The third stage: 190±2℃, far-infrared heating, stay for 8 minutes, the condensation reaction tends to be complete at high temperature, and at the same time the acrylate and organosilicon network are further integrated to form an interpenetrating network structure (IPN) to improve the interfacial bonding strength.

[0062] Post-processing: After natural cooling to room temperature, the material undergoes online spark testing (6kV). If no breakdown points are found, it is then wound up. Finally, it is slit into finished insulating tapes with a width of 20±0.2mm according to requirements.

[0063] Example 2: 1. The raw materials and formula differ from those in Example 1 in the following ways: Interface layer: The amount of phase change microcapsules was increased to 18 parts to enhance the heat absorption buffering capacity under overload.

[0064] The high thermal conductivity layer of the mica band: the amount of carboxylated multi-walled carbon nanotubes is increased to 12 parts, and aluminum nitride is increased to 28 parts, to improve the filler percolation threshold and thermally conductive network density. The magnetic field strength is increased to 0.8T to ensure better orientation.

[0065] Intumescent flame retardant layer: Same as in Example 1.

[0066] Ceramicized layer: Same as in Example 1.

[0067] 2. The preparation method differs from that in Example 1 in that: In step S2: the weight gain of the high thermal conductivity dry film is increased to 45 g / m² to increase the thickness of the thermal conduction path. The rest is the same as in Example 1.

[0068] Example 3: 1. The raw materials and formula differ from those in Example 1 in the following ways: Interface layer: The amount of phosphorus-containing acrylate monomer is increased to 12 parts, and the glass powder with a slightly lower softening point of 360°C is selected to promote the earlier formation of ceramic protective layer.

[0069] High thermal conductivity layer of gradient mica strip: The formulation is the same as that of Example 1.

[0070] Intumescent flame retardant layer: The amount of ammonium polyphosphate is increased to 28 parts and tin phosphide is increased to 7 parts to enhance the expansion ratio and char layer strength.

[0071] Ceramicized layer: The amount of nano-zirconia is increased to 18 parts and zinc borate to 9 parts to form a denser and stronger ceramic body.

[0072] 2. The preparation method differs from that in Example 1 in that: In step S2: the dry film weight gain of the expanded layer and the ceramic layer is increased to 70 g / m² and 55 g / m², respectively.

[0073] In step S4, the curing temperature for the third stage is adjusted to 200℃ / 6min to further ensure complete pre-crosslinking of the interface layer.

[0074] Example 4 The difference between the formulation and Example 1 is that: Interface layer: 8 parts of phosphorus-containing acrylate monomer (PETA-P), 12 parts of hydroxyethyl acrylate (HEA), 20 parts of polyurethane acrylate prepolymer, 20 parts of hydroxyl-terminated polydimethylsiloxane (HTPDMS, 1000cP), 10 parts of phase change microcapsules (65℃), 5 parts of low melting point borosilicate glass powder (softening point 380℃), 0.2 parts of dibutyltin dilaurate, and 1.5 parts of tetraethyl orthosilicate.

[0075] Basalt fiber woven layer: 200tex basalt fiber three-dimensional plain weave fabric (area density 280g / m²). Surface treatment sol: KH-550 to nano-silicon carbide (40nm) mass ratio 7:3, solid content 2%.

[0076] Gradient mica band layer: High thermal conductivity layer: 100 parts of polyimide precursor (20% solid content), 5 parts of carboxylated multi-walled carbon nanotubes (length ~15μm), 10 parts of aluminum nitride (particle size 3μm), and 0.5 parts of PVP dispersant.

[0077] Intumescent flame retardant layer: 100 parts of water-based acrylic emulsion (45% solid content), 20 parts of ammonium polyphosphate (Type II), 8 parts of pentaerythritol, 6 parts of melamine, 3 parts of tin phosphide, and 1 part of ammonium molybdate.

[0078] Ceramicized layer: 100 parts methyltrimethoxysilane, 10 parts nano-zirconium dioxide (30nm), 5 parts zinc borate (fire retardant grade), 2 parts acetic acid, and 200 parts ethanol / water = 2 / 1 mixed solvent.

[0079] Example 5 The difference between the formulation and Example 1 is that: Interface layer: 12 parts of phosphorus-containing acrylate monomer (PETA-P), 30 parts of hydroxyethyl acrylate (HEA), 30 parts of polyurethane acrylate prepolymer, 40 parts of hydroxyl-terminated polydimethylsiloxane (HTPDMS, 1000cP), 20 parts of phase change microcapsules (65℃), 10 parts of low melting point borosilicate glass powder (softening point 380℃), 0.2 parts of dibutyltin dilaurate, and 2 parts of tetraethyl orthosilicate.

[0080] Basalt fiber woven layer: 200tex basalt fiber three-dimensional plain weave fabric (area density 280g / m²). Surface treatment sol: KH-550 to nano-silicon carbide (40nm) mass ratio 7:3, solid content 2%.

[0081] Gradient mica band layer: High thermal conductivity layer: 100 parts of polyimide precursor (20% solid content), 15 parts of carboxylated multi-walled carbon nanotubes (length ~15μm), 30 parts of aluminum nitride (particle size 3μm), and 2 parts of PVP dispersant.

[0082] Intumescent flame retardant layer: 100 parts of water-based acrylic emulsion (45% solid content), 30 parts of ammonium polyphosphate (Type II), 12 parts of pentaerythritol, 10 parts of melamine, 8 parts of tin phosphide, and 3 parts of ammonium molybdate.

[0083] Ceramicized layer: 100 parts methyltrimethoxysilane, 20 parts nano-zirconium dioxide (30nm), 10 parts zinc borate (fire retardant grade), 5 parts acetic acid, and 300 parts ethanol / water = 2 / 1 mixed solvent.

[0084] Comparative Example 1: 1. The raw materials and formula differ from those in Example 1 in the following ways: Interface layer: The amount of HTPDMS was increased to 35 parts to improve overall flexibility. The amount of glass powder was reduced to 6 parts.

[0085] Basalt fiber woven layer: Two-dimensional twill woven fabric (area density 220g / m²) is used instead of three-dimensional weaving to reduce costs and improve flexibility. Surface treatment is the same as in Example 1.

[0086] The high thermal conductivity layer of gradient mica banding: the amount of carboxylated carbon nanotubes is reduced to 5 parts, and the thermal conductivity is mainly provided by 25 parts of aluminum nitride, thus reducing costs.

[0087] Intumescent flame retardant layer and ceramicized layer: The formulation is the same as in Example 1.

[0088] 2. The preparation method differs from that in Example 1 in that: In step S4: the wet film thickness of the interface layer is reduced to 150 μm to reduce material usage and curing shrinkage stress.

[0089] The curing process is as follows: 80℃, 10min → 120℃, 15min → 180℃, 5min.

[0090] Comparative Example 2: 1. The raw materials and formula are the same as those in Example 1.

[0091] 2. The preparation method differs from that in Example 1 in that: The mica tape layer adopts a double-layer composite coating method, that is, the high thermal conductivity layer and the expansion flame retardant layer are first co-extruded and coated on the same side at one time, and then the ceramicized layer is coated on the other side after drying.

[0092] Experimental Example Sample preparation: Insulating composite tapes were prepared based on the formulations and processes of Examples 1-5 and Comparative Examples 1-2; Cable sample preparation: The above-mentioned tape is wrapped around a tinned copper conductor with a diameter of 1.5 mm² with a 50% overlap rate (2 layers of wrapping) to make a single-core simulated cable sample for fire protection, electrical and other tests.

[0093] Test environment: temperature 23±2℃, relative humidity 50±5%.

[0094] Data processing: Each test group should have at least 5 parallel samples, and the average value should be taken.

[0095] The test methods for insulating material tapes are as follows: Tensile strength (longitudinal): GB / T1040.3-2006; Elongation at break: GB / T1040.3-2006; Tear strength (Elmendorf method): GB / T16578.1-2008; Flexibility (minimum bending radius): GB / T2423.39-2018; Axial thermal conductivity: ASTM D5470-17; Phase transition enthalpy: ISO 11357-3:2018; Limiting oxygen index: GB / T2406.2-2009; Vertical flammability rating: GB / T18380.12-2008; Smoke density (minimum transmittance): GB / T8323.2-2008; Fire resistance performance (BS6387:2013), Option C (950℃ flame); Option W (650℃ flame + water spray); Option Z (950℃ flame + vibration); Carbonization length (mm, 750℃, 90min): IEC60331-2:2018; Volume resistivity (×10)14 Ω·cm): GB / T1410-2006; Dielectric strength (kV / mm): GB / T1408.1-2016; Dielectric loss factor (50Hz): GB / T1409-2006; Tensile strength retention rate (%) and volume resistivity change rate (%) after damp heat aging (85℃, 85%RH, 1000h): GB / T2423.3-2016; After thermal cycling (-40℃ / 150℃, 50 cycles): GB / T2423.22-2012 The test results are shown in Table 1.

[0096] Table 1

[0097] From Table 1, we can conclude that: Example 1: Excellent and balanced performance across all aspects, with an axial thermal conductivity of 1.75 W / (m·K), fire resistance fully meeting the CWZ requirements (45 / 18 min) in BS 6387, and a volume resistivity as high as 8.5 × 10⁻⁶. 14 Ω·cm.

[0098] Example 2: By increasing the thermally conductive filler (CNT to 12 parts, AlN to 28 parts) and phase change microcapsules (to 18 parts), the axial thermal conductivity was significantly improved to 2.20 W / (m·K), and the phase change enthalpy was increased to 32.5 J / g, verifying its excellent overload thermal management capability. Its fire resistance (W / Z scheme: 42 / 16 min) was comparable to that of Example 1.

[0099] Example 3: By improving the flame retardant system (APP increased to 28 parts, tin phosphide increased to 7 parts), ceramic filler, and using glass powder with a lower softening point, optimal fire resistance and smoke suppression performance (LOI 50.5%, smoke transmittance 28%, W / Z scheme: 68 / 25min) was achieved. The shortest char length (20 mm) proves that the formed ceramic barrier is the most effective.

[0100] Example 4: By optimizing the formulation (reducing the amount of CNTs, AlN, and functional monomers) and using two-dimensional woven fabric, significant advantages were achieved in cost (estimated at 70% of the baseline), thickness (0.35 mm), areal density (420 g / m²), and flexibility (bending radius 2D). Its core properties (LOI 44.5%, fire resistance W / Z: 38 / 15 min, volume resistivity 6.0 × 10⁻⁶) were also observed. 14Although the Ω·cm is lower than that of Example 1, it still fully meets and significantly exceeds the requirements of GB / T 19666-2019 and other standards for Class A flame-retardant and fire-resistant cables, and has extremely high market competitiveness.

[0101] Example 5: By using the upper limit of the raw material usage for each functional layer, top-notch comprehensive performance was achieved, particularly in mechanical strength (142 MPa), thermal conductivity (2.35 W / (m·K)), and refractoriness (W / Z: 65 / 24 min). Its volume resistivity (5.5 × 10⁻⁶) was also excellent. 14 The Ω·cm (Ω·cm) decreased slightly, possibly due to the high filler content, but remained at an excellent level. This example represents the theoretical upper limit of the performance of this solution.

[0102] Comparative Example 1: By employing two-dimensional braiding and reducing the amount of CNTs, the axial thermal conductivity (1.00 W / (m·K)) and fire resistance (W / Z: 28 / 12 min) decreased significantly, and the performance retention rate after damp heat aging was also the lowest. This demonstrates that the mechanical support provided by the three-dimensional braided skeleton and the continuous axial thermal network constructed with sufficient CNTs are crucial for ensuring the long-term reliability and overall high performance of the material under harsh environments.

[0103] Comparative Example 2: Using a non-gradient process of "double-layer co-extrusion + single-sided coating", its performance was worse than that of Example 1 in several dimensions, especially in fire resistance (W / Z: 40 / 16 min) and interlayer bonding stability (local whitening after thermal cycling). This demonstrates that the three-layer co-surface gradient coating process is crucial for achieving optimal distribution of functional layers, ensuring excellent interlayer bonding, and achieving the final performance.

Claims

1. A fireproof insulation material for indoor cables and wires, characterized in that, The insulating material comprises a basalt fiber braided layer, an interface layer, and a mica tape layer arranged sequentially. The interface layer, by weight, comprises the following raw materials: 8-12 parts of phosphorus-containing acrylate monomer, 12-30 parts of hydroxyethyl acrylate, 20-30 parts of acrylate prepolymer, 20-40 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of phase change microcapsules, 5-10 parts of glass powder, 0.1-0.6 parts of dibutyltin dilaurate, and 1-3.2 parts of tetraethyl orthosilicate; The basalt fiber woven layer includes: a three-dimensional basalt fiber skeleton fabric and nano-silicon carbide loaded on the surface of the three-dimensional basalt fiber skeleton fabric; The mica tape layer includes: mica paper, high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry.

2. The fireproof insulation material for indoor cables and wires according to claim 1, characterized in that, The high thermal conductivity slurry comprises, by weight, 100 parts of polyimide precursor, 5-15 parts of carboxylated multi-walled carbon nanotubes, 10-30 parts of aluminum nitride powder, and 0.5-2 parts of dispersant.

3. The fireproof insulation material for indoor cables and wires according to claim 1, characterized in that, The intumescent flame retardant slurry comprises, by weight, 100 parts of water-based acrylate binder, 20-30 parts of ammonium polyphosphate, 8-12 parts of pentaerythritol, 6-10 parts of melamine, 3-8 parts of tin phosphide, and 1-3 parts of ammonium molybdate.

4. The fireproof insulation material for indoor cables and wires according to claim 1, characterized in that, The ceramic precursor slurry comprises, by weight, 100 parts of methyltrimethoxysilane, 10-20 parts of zirconium dioxide, 5-10 parts of zinc borate, 2-5 parts of acetic acid, and 200-300 parts of solvent.

5. The fireproof insulation material for indoor cables and wires according to claim 1, characterized in that, The phase change microcapsules have silicon dioxide as the wall material and paraffin as the core material.

6. The fireproof insulation material for indoor cables and wires according to claim 1, characterized in that, The softening point of the glass powder is less than 380°C.

7. A method for preparing an indoor fire-resistant insulation material for cables and wires as described in any one of claims 1-6, characterized in that, Includes the following steps: S1, γ-aminopropyltriethoxysilane and anhydrous ethanol are mixed at a volume ratio of 1:9, hydrolyzed, and then nano-silicon carbide powder is added and ultrasonically dispersed to obtain a sol; three-dimensional basalt fiber skeleton fabric is passed through a sol tank containing the sol at a speed of 1-3 m / min for impregnation treatment; and dried in an oven at 80-120℃ to obtain a basalt fiber woven layer. S2, respectively prepare high thermal conductivity slurry, intumescent flame retardant slurry, and ceramic precursor slurry; let the mica paper base tape pass through the multi-stage slit coating equipment in sequence, coat the high thermal conductivity slurry at the first slit coating head, dry and apply a magnetic field at the same time, and obtain a thermally conductive layer after curing. Then, the intermediate layer slurry is applied through the second slit coating head, and after drying, the expanded layer is obtained. The ceramic precursor slurry is then coated through the third slit coating head and cured to obtain the ceramic precursor layer; after winding and aging, the mica tape layer is obtained. S3, phosphorus-containing acrylate monomers, hydroxyethyl acrylate, and a portion of acrylate prepolymer are mixed to obtain the matrix phase; In the matrix phase, phase change microcapsules and glass powder with surface treated with silane coupling agent are added and stirred to disperse evenly; Then add hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate and tetraethyl orthosilicate, and stir under vacuum to obtain the interface layer slurry; S4. Unfold the basalt fiber braided layer, coat one side with an interface layer slurry, attach the uncoated side of the mica tape layer to the interface layer slurry, and roll it to obtain a wet preform. The wet preform is cured in sections, naturally cooled to room temperature, rolled up, and cut to obtain the insulating material.

8. The method for preparing fire-resistant insulation material for indoor cables and wires according to claim 7, characterized in that, The segmented curing includes; First stage: Curing at 80-90℃ for 5-8 minutes; Second stage: Curing at 120-130℃ for 15-20 minutes; Third stage: Curing at 180-200℃ for 5-8 minutes.

9. The method for preparing fire-resistant insulation material for indoor cables and wires according to claim 7, characterized in that, In S2, the thickness of the thermally conductive layer after curing is 20-50 g / m. 2 The thickness of the expansion layer is 40-80 g / m. 2 The thickness of the ceramic precursor layer is 30-60 g / m. 2 .

10. The method for preparing fire-resistant insulation material for indoor cables and wires according to claim 7, characterized in that, In step S3, the mass ratio of the matrix phase to the hydroxyl-terminated polydimethylsiloxane is (1.5-2.5):1.

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