Fireproof alumina fiber-containing cable outer sheath material

Abstract

The invention discloses a fireproof alumina fiber-containing cable outer sheath material. The cable outer sheath material comprises a basic plastic component and a fireproof filler added into the basic plastic component, wherein the refractory filler is formed by loading a phase change material on alumina fibers. In the scheme, after the phase change material is loaded on the alumina fiber, the alumina fiber has good thermal conductivity to the ambient temperature, and the phase change material may absorb heat conducted by the alumina fiber through phase change so as to reduce the ambient temperature of the alumina fiber, thereby further improving the fire resistance of the outer sheath.

Description

Technical Field

[0001] The present application relates to the technical field of cables, and in particular to a fire-resistant cable outer sheath material containing aluminum oxide fibers. Background Art

[0002] In recent years, with the frequent occurrence of high-voltage power cable fire accidents, the fire resistance of wires and cables has gradually attracted attention. Therefore, flame-retardant cable materials have been used more and more widely in recent years. It is a multi-component mixed material based on polyethylene resin and other materials with various compounding agents. Due to its superior mechanical properties, good weather resistance, excellent electrical insulation performance, easy processing and low cost, it is widely used in insulation and sheath materials of wires and cables.

[0003] In related technologies, the fire resistance of cable outer sheath materials needs to be improved. Summary of the Invention

[0004] Issues to be addressed

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present application is to provide a fire-resistant alumina fiber-containing cable outer sheath material and a cable to better improve fire resistance.

[0006]

Methods for solving the problem

[0007] In the related art, in order to improve the fire resistance of the cable outer sheath, some conventional refractory fillers are usually added in combination or specifically screened, such as magnesium oxide, magnesium oxide, silicon nitride, silicon carbide, vermiculite, graphene, aramid fiber, and glass fiber. The fire resistance of these refractory fillers is generally passive, that is, the high temperature resistance of the filler itself is used to give the cable outer sheath a certain fire resistance. The fire resistance brought about by these methods is relatively limited.

[0008] To address the aforementioned challenges, the inventors conducted extensive research and realized that, based on this realization, they creatively discovered that when a phase change material is loaded onto alumina fibers, the alumina fibers themselves exhibit good thermal conductivity to the surrounding temperature. The phase change material absorbs heat conducted by the alumina fibers through phase change, lowering the temperature around the alumina fibers and further improving the fire resistance of the outer sheath. This led to the present invention.

[0009] On one hand, the present application provides a fire-resistant alumina fiber-containing cable outer sheath material, comprising a basic plastic component and a refractory filler added to the basic plastic component;

[0010] Wherein, the refractory filler is formed by phase change material loaded on alumina fiber.

[0011] In any embodiment, the phase change material is a water-bound inorganic salt phase change material.

[0012] In any embodiment, the method of loading the phase change material on the alumina fiber includes:

[0013] A1. Provide a phase change material dispersion;

[0014] A2. Immersing the alumina fiber in a phase change material dispersion;

[0015] A3. Dry the impregnated alumina fibers.

[0016] In any embodiment, the concentration of the phase change material dispersion is 3-16 wt %, the immersion time is 15-40 min, and the immersion is performed under ultrasonic dispersion.

[0017] In any embodiment, before A2, the method of loading the phase change material on the alumina fiber further includes activating the alumina fiber;

[0018] The activation treatment selects at least one of the following operation items:

[0019] Plasma treatment under inert atmosphere;

[0020] Immersed in acid-base regulating solution;

[0021] Dipping in silicone coupling agent.

[0022] In any embodiment, the loading amount of the phase change material is 4-23 wt % based on the weight of the alumina fiber.

[0023] In any embodiment, the refractory filler is added in an amount of 6-18 wt % based on the weight of the alumina fiber.

[0024] In any embodiment, the refractory filler has an aspect ratio of 6-13.

[0025] In any embodiment, the porosity of the refractory filler is 75-85%.

[0026] On the other hand, the present application provides a fire-resistant alumina fiber-containing cable, including the fire-resistant alumina fiber-containing cable outer sheath material as described above.

[0027] Effects of the invention

[0028] The fire-resistant alumina fiber-containing cable outer sheath material provided in this application has high fire resistance. DETAILED DESCRIPTION

[0029] Below, detailed description specifically discloses the embodiment of the present application. However, there may be cases where unnecessary detailed description is omitted. For example, there may be cases where detailed description of well-known matters and repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims. The "range" disclosed in this application is defined in the form of lower limits and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is also expected to be understood that the ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values are 1 and 2, and if the maximum range values are 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is stated as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on.

[0030] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0031] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0032] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0033] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0034] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035]

Cable outer sheath material

[0036] As used herein, the term "cable outer sheath material" refers to the material properties used to characterize the cable outer sheath other than its shape or structure, and includes both the raw material (raw material) of the cable outer sheath and the molded material obtained by conventional plastic processing of the raw material.

[0037] The fire-resistant alumina fiber-containing cable outer sheath material disclosed herein comprises a basic plastic component and a refractory filler added to the basic plastic component; wherein the refractory filler is formed by a phase change material loaded on alumina fibers.

[0038] Regarding the amount of refractory filler added, those skilled in the art can obtain it through routine tests based on the refractory properties and other properties sought after for specific requirements, such as mechanical properties and aging resistance. Suitable but non-limiting addition amounts of refractory filler are 6-18wt% based on the weight of the alumina fiber, with exemplary addition amounts being 6.2-18wt%, 6.5-18wt%, 7-18wt%, 7.5-18wt%, 8-18wt%, 8.5-18wt%, 9-18wt%, 10-18wt%, 11-18wt%, 12-18wt%, 13-18wt%, 14-18wt%, 15-18wt%, 16-18wt%, 17-18wt%, 6-17.5wt%, 6-17.0wt%, 6-16.5wt%, 6-16.0wt%, 6-15.5wt%, 6-15wt%, 6-14wt%, 6-13wt%, 6-12wt%, 6-11wt%, 6-10wt%, 6-9.5wt%, 6-9wt%, 6-8wt%, 6-7.0wt%, and the like.

[0039] If too little refractory filler is added, the fire resistance of the cable outer sheath will be reduced; if too much is added, the mechanical properties of the cable (such as fracture resistance and toughness) will be damaged.

[0040]

Alumina fiber

[0041] The ratio of alumina fiber length to diameter (i.e., aspect ratio) defines the two-dimensional characteristics of alumina fiber, determines the length of the fiber, and thus affects the mechanical properties of the cable sheath material. More importantly, it affects its fire resistance.

[0042] A suitable but non-limiting aspect ratio of the alumina fiber is 6-13, and examples thereof include 6.2-13, 6.5-13, 6.8-13, 7-13, 7.5-13, 8-13, 9-13, 9.5-13, 10-13, 10.5-13, 11-13, 11.5-13, 12-13, 6-12.5, 6-12, 6-11, 6-10, 6-9.5, 6-9, 6-8.5, 6-8, 6-7, etc. Within this range, the aspect ratio can better balance mechanical properties and fire resistance.

[0043] Suitable but non-limiting pore sizes of the alumina fibers are 75-85, and can be exemplified by 75.5-85, 76-85, 78-85, 80-85, 82-85, 75-84.5, 75-84, 75-83, 75-82, 75-81, 75-80, 75-78, 75-77, etc. This specific range of pore sizes can better balance mechanical properties and fire resistance.

[0044] It should be noted that the aspect ratios and porosity of alumina fibers in the aforementioned ranges are within conventional alumina standards, meaning that conventionally obtained alumina fibers possess these aspect ratios and porosity. If established commercial channels cannot precisely meet the required aspect ratios and porosity, conventional methods can be used to prepare these fibers.

[0045] Conventional methods for preparing alumina fibers include sol-gel, melt spinning, chemical vapor deposition (CVD), electrospinning, impregnation-sintering, and coprecipitation. The sol-gel method involves dissolving an aluminum alkoxide or aluminum salt in an organic solvent to form a uniform solution (sol), which is then converted into a gel-like substance through hydrolysis and polymerization under certain conditions. The gel is dried to remove the solvent, resulting in a precursor fiber, which is then converted into alumina fibers through high-temperature calcination.

[0046] Melt spinning involves heating a mixture containing aluminum oxide and other additives to above its melting point to form a melt. The melt is then extruded through fine orifices and rapidly cooled to solidify. The fibers are then heat-treated to remove impurities and increase crystallinity. Chemical vapor deposition (CVD) involves reacting an aluminum-containing gas (such as aluminum chloride vapor) with oxygen or other oxidants at a specific temperature to deposit aluminum oxide films or fibers on a substrate. The fiber microstructure and properties can be manipulated by adjusting process parameters. Electrospinning utilizes a charged jet under a high-voltage electric field to stretch and refine a polymer solution or melt, forming nanofibers. For alumina fibers, a spinning solution containing an aluminum oxide precursor is typically prepared. After spinning, the fibers are then sintered to form alumina fibers. In the impregnation-sintering method, a prefabricated organic or inorganic fiber skeleton is immersed in a solution containing an aluminum source, allowing aluminum ions to penetrate the fibers. After drying, the fibers are sintered at high temperatures, converting the aluminum source into aluminum oxide, which then fills the interstices between the fibers or coats the fiber surfaces. The co-precipitation method involves adding a precipitant to a solution containing aluminum ions, causing the aluminum ions to form aluminum hydroxide precipitates. The precipitates are then filtered, washed, and dried to produce aluminum hydroxide powder. The aluminum hydroxide powder decomposes at high temperatures and converts into aluminum oxide, which can then be processed into fibers.

[0047] [Refractory filler obtained by loading phase change material on alumina fiber]

[0048] As used herein, "phase change material loaded on alumina fiber load" means that the phase change material is in an attached state formed by physical action (such as molecular adsorption force or electrostatic action or molecular hydrogen bond or van der Waals force) and / or chemical bond (such as bonding between active groups such as carboxyl and hydroxyl groups).

[0049] This article does not specifically limit the type of phase change material. In the absence of particularly stringent requirements, the phase change material can be in any conventional form, and can be an organic phase change material represented by paraffin, fatty acids (such as stearic acid, palmitic acid, etc.), and polyols (such as ethylene glycol, glycerol); it can also be an inorganic phase change material represented by crystalline hydrated salts (such as nitrates, sulfates), molten salts (chlorides, fluorides), metals or alloys (such as lead, bismuth); it can also be an inorganic-organic phase change material represented by paraffin-carbon nanotube composite materials, etc.

[0050] However, considering the fire temperatures encountered in cable fire resistance scenarios, such as 200-800 degrees Celsius, it is desirable for the phase change material to undergo a phase change at an appropriate time within this fire temperature range. This means that the phase change temperature should overlap within this range to avoid premature phase change, which could cause the phase change material to complete its mission too quickly, or late phase change, which could prevent the phase change material from failing to perform its inherent function. A specific, but non-limiting, example of a suitable phase change material is a water-bound inorganic salt phase change material, which ensures that the phase change temperature range is consistent with the common fire temperature of cables.

[0051] It is easy to imagine that in the implementation method where the phase change material is an organic phase change material or an inorganic-organic phase change material, although theoretically it cannot be ruled out that the organic phase change material may cause cable fire and provide combustion medium due to its carbon content, in actual operation this risk can be basically avoided by reducing the amount of organic phase change material added.

[0052] Based on general material science knowledge, it is easy for technicians in this field to think that the phase change material can be loaded on the alumina fiber through impregnation, spraying, original synthesis, etc. without excessive effort.

[0053] Based on the purpose of convenient operation and the consideration of better dispersion of alumina fiber, the more suitable method is the impregnation method. The impregnation method can be demonstrated as follows:

[0054] A1. Provide a phase change material dispersion;

[0055] A2. Immersing the alumina fiber in a phase change material dispersion;

[0056] A3. Dry the impregnated alumina fibers.

[0057] In A1, the dispersion medium used in the phase change material dispersion can be water or a hydrophilic medium, such as a C1-4 alcohol, a C1-4 amine solvent, DMSO, or the like. The dispersion process of the phase change material can be achieved using standard experimental techniques, such as mechanical stirring, ultrasonic dispersion, or the addition of a cosolvent. Of course, the effectiveness of this technical solution is not specifically dependent on the uniformity of the phase change material dispersion. The adverse effects of the heterogeneous state can be compensated by auxiliary ultrasonic dispersion in the subsequent step A2.

[0058] In A2, the alumina fibers are immersed in a phase-change material dispersion. The phase-change material diffuses toward the alumina fiber interface not simply due to concentration differences, but rather relies on the physical adsorption force inherent in the porous structure of the alumina fibers. This physical adsorption ensures that the phase-change material remains substantially adhered to the alumina fiber surface even in relatively low-concentration precursor solutions, thereby ensuring a substantially satisfactory level of hydroxide flame retardant loaded on the alumina fiber surface.

[0059] The concentration of the phase change material dispersion is preferably 3-16wt%, and can be exemplified by 3-15wt%, 3-14wt%, 3-13wt%, 3-12wt%, 3-11wt%, 3-10wt%, 3-9wt%, 3-8wt%, 3-7wt%, 3-6wt%, 3-5wt%, 3-4wt%, 3.5-15wt%, 4-15wt%, 4.5-15wt%, 5-15wt%, 6-15wt%, 7-15wt%, 8-15wt%, 9-15wt%, 10-15wt%, 11-15wt%, 12-15wt%, 13-15wt%, 14-15wt%, etc.; the immersion time More preferably, it is 15-40 min, and can be exemplified by 15.5-40 min, 16-40 min, 17-40 min, 19-40 min, 21-40 min, 23-40 min, 25-40 min, 28-40 min, 30-40 min, 32-40 min, 35-40 min, 38-40 min, 15-38 min, 15-35 min, 15-32 min, 15-30 min, 15-28 min, 15-26 min, 15-24 min, 15-22 min, 15-20 min, 15-18 min, and 15-17 min; the immersion is carried out under ultrasonic dispersion.

[0060] Therefore, the impregnation performed under the concentration of the specific phase change material dispersion, the impregnation time, and the impregnation auxiliary conditions can obtain a more appropriate phase change material loading amount.

[0061] Here, the ultrasonic-related process parameters immersed in ultrasonic dispersion can be exemplified as: ultrasonic power of 800-1200W, for example, 820-1200W, 850-1200W, 900-1200W, 920-1200W, 950-1200W, 1000-1200W, 1050-1200W, 1100-1200W, 1150-1200W, 800-1180W, 800-1150W, 800-1100W, 800-1050W, 800-1000W, 800-950W, 800-900W, etc.

[0062] In order to shorten the impregnation time, the A2 process can be carried out under vacuum or reduced pressure, for example, the vacuum degree can be demonstrated to be 0.1-0.5 kPa, etc. Of course, the vacuum can also promote the penetration of the phase change material into the alumina fiber by creating a lower pressure inside the alumina fiber than outside.

[0063] Drying in A3 is preferably performed below the phase change temperature of the phase change material, exemplified by 60-80°C, including 62-80°C, 65-80°C, 68-80°C, 70-80°C, and 75-80°C. The drying time and method are primarily based on the absence of visible dispersion medium. The drying end point can also be determined by measuring the dispersion medium content using a moisture meter or similar instrument. Air drying is also an option.

[0064] In the above-mentioned dipping method, a polymer coating (such as polyurethane) can be used to encapsulate the phase change material layer after A3 to prevent it from dissipating when not in use, as some of it is volatile.

[0065] As previously discussed, the more suitable phase change material is a water-bound inorganic salt phase change material. This phase change material also achieves the purpose: the water-bound inorganic salt phase change material has a high molecular compatibility with the alumina fiber, avoiding the poor adhesion between the phase change material and the alumina fiber. However, to further improve the adhesion between the phase change material and the alumina fiber, the method of loading the phase change material onto the alumina fiber before A2 also includes activating the alumina fiber.

[0066] The activation treatment is performed by selecting at least one of the following operation items:

[0067] Plasma treatment under inert atmosphere;

[0068] Immersed in acid-base regulating solution;

[0069] Dipping in silicone coupling agent.

[0070] The purpose of the plasma treatment is to create a slightly roughened surface structure on the alumina fibers, thereby facilitating the attachment of the phase change material. The inert atmosphere is designed to isolate oxygen, preventing oxygen from intercalating into the alumina fibers and disrupting the visible defects in the alumina lattice, thereby degrading the alumina structure. The parameters of the plasma treatment can be adjusted based on routine experimentation.

[0071] The purpose of immersion in the acid-base solution is to create active groups on the alumina fiber surface through the hydrogen protons provided by the acid or the hydroxide radicals provided by the alkali solution. These groups interact chemically or physically with the hydrogen-containing groups in the phase change material, thereby achieving adhesion. The acid-base solution can be a conventional non-oxidizing acid, such as dilute sulfuric acid or dilute hydrochloric acid; the alkali solution can be sodium hydroxide or potassium hydroxide. The immersion time can be adjusted according to conventional needs.

[0072] The purpose of the above-mentioned siloxane coupling agent impregnation project is to use the siloxane coupling agent to form a bridge between the phase change material and the alumina fiber. Conventional siloxane coupling agents such as KH-550, KH-560, and KH-570 can be used.

[0073] One method for attaching phase change material to alumina fibers is spray coating, a process readily understood by those skilled in the art. An exemplary process is as follows: B1. Mix the phase change material with a film-forming resin (e.g., epoxy resin or PEG-based carrier), followed by ball milling to a target particle size. B2. Under an inert gas (e.g., nitrogen), spray the material onto the alumina fiber surface at an appropriate speed (e.g., 50-100 mm / s).

[0074] B3. Curing under heating conditions (e.g. 110-120°C) for 2-4 hours to form a uniform coating.

[0075] It is worth adding that in B2, the spraying tool can adopt the existing technology to implement the spraying equipment with micron-level stroke, which will not be described in detail here.

[0076] One method for loading a phase change material onto alumina fibers is in-situ synthesis, a process readily understood by those skilled in the art. An exemplary method is as follows: C1. Immerse the alumina fibers in an aqueous solution containing a precursor (e.g., Al(NO₃)₃·9H₂O and the phase change material); B2. Hydrothermal reaction at, for example, 90°C for 6 hours to promote in-situ crystallization of the phase change material within the fiber pores; B3. Centrifugal washing and drying at, for example, 60°C to obtain a core-shell composite material.

[0077] As discussed above, in the implementation method of loading by impregnation, the concentration of the dispersion, the impregnation time, and the impregnation performed under the impregnation auxiliary conditions can obtain a more suitable loading amount of the phase change material. As a suitable but non-limiting loading amount, it is 4-23wt% based on the weight of the alumina fiber, and can be exemplified by 4.2-23wt%, 4.5-23wt%, 5-23wt%, 5.5-23wt%, 6-23wt%, 6.5-23wt%, 7-23wt%, 8-23wt%, 9-23wt%, 10-23wt%, 11-23wt%, 12-23wt%, 15-2 3wt%, 18-23wt%, 20-23wt%, 4-22wt%, 4-21wt%, 4-20wt%, 4-19wt%, 4-18wt%, 4-17wt%, 4-16wt%, 4-15wt%, 4-14wt%, 4-13wt%, 4-12wt%, 4-10wt%, 4-9wt%, 4-8wt%, 4-7wt%, 4-6wt%, etc.

[0078] If the load is too much, the adhesion of the phase change material to the alumina fiber may be damaged, and it is not conducive to the alumina fiber to impart its basic mechanical properties to the outer sheath.

[0079] Those skilled in the art can refer to existing technologies for determining the loading capacity of porous materials. Conventional measurement methods include gravimetric analysis, microscopic imaging technology, and GB / T 7714-2018: China National Standard for Porosity Testing of Porous Materials.

[0080] The principle of gravimetric analysis is to measure the difference in mass between a material before and after adsorption. The actual process involves pre-treating the material (drying, high-temperature activation, etc. to remove impurities). Then, the material is immersed in the adsorption medium (such as water, an organic solvent, or a gas) under controlled temperature and humidity to reach equilibrium. Residual surface liquid is removed by centrifugation or vacuum extraction. The change in mass is then measured as the loading.

[0081] Microscopic imaging techniques (to assist qualitative analysis) can be performed using SEM / TEM electron microscopy and XPS / EDS elemental analyzers. SEM / TEM electron microscopy: Observe the surface morphology and pore distribution of the material to verify uniform loading. XPS / EDS: Analyze the chemical composition of the adsorbed species and the influence of surface functional groups, thereby determining the loaded phase change material content.

[0082]

Basic plastic components

[0083] The base plastic component of this application can be any type of plastic used in cables, provided that the type of plastic does not affect the fire-resistant properties of the refractory filler. Examples of such plastics include cross-linked polyethylene (XLPE), high-density polyethylene, polyvinyl chloride, polypropylene, ethylene-vinyl acetate copolymer, fluoroplastics (e.g., polytetrafluoroethylene (PTFE), fluoroethylene propylene (FEP)), silicone rubber, ethylene propylene rubber (EPR), nylon, and the like.

[0084] The types and amounts of conventional processing aids for cable sheaths that are widely known in the art do not play a decisive role in the fire-resistant properties of the refractory filler of this application. These processing aids can be listed as follows:

[0085] a. Plasticizers, which are used to increase the flexibility and processing fluidity of plastics by increasing the distance between plastic molecular chains. Typical examples of plasticizers are phthalates (such as DOP and DINP) and phosphates.

[0086] b. Stabilizers, used to inhibit material decomposition caused by heat, light or oxidation during processing or use, such as the inhibition of hydrogen chloride release from PVC at high temperatures. Lead salts (lead sulfate) and calcium-zinc composite stabilizers are typical representatives;

[0087] c. Antioxidants, used to delay oxidative degradation of materials, improve heat resistance and service life, with hindered phenols (such as BHT), phosphites, and thioesters as typical representatives;

[0088] d. Lubricants, used to reduce friction between plastics and equipment during processing and improve surface smoothness, with stearic acid, paraffin, polyethylene wax, etc. as typical representatives;

[0089] e. Fillers, used to reduce costs and improve material rigidity, heat resistance or insulation properties;

[0090] f. Cross-linking agents, used to promote the cross-linking of polyethylene (PE) to form a three-dimensional network structure, thereby improving heat resistance and mechanical strength35, with dicumyl peroxide (DCP) and silane coupling agents being typical representatives;

[0091] g. Light stabilizers, used to absorb or shield ultraviolet rays and delay the aging of outdoor cables. Typical examples include carbon black (light shielding agent) and benzotriazole ultraviolet absorbers (such as UV327);

[0092] h. Dispersants, used to improve the interface bonding between inorganic fillers and plastic matrix and enhance filling uniformity, with silane coupling agents and titanate coupling agents as typical representatives;

[0093] i. Antistatic agent, used to prevent static electricity accumulation by reducing surface resistance.

[0094] Regarding the specific composition of the basic plastic component and the processing aid, some implementation forms applicable to the above-mentioned refractory filler of this application can be demonstrated as follows:

[0095] a. Polyvinyl chloride (PVC) system plastic

[0096] PVC resin: 100 parts; dioctyl phthalate (DOP): 30-40 parts (plasticizer, improves flexibility); tribasic lead sulfate: 4-5 parts (stabilizer, inhibits thermal decomposition); stearic acid: 0.5-1 part (lubricant, improves processing performance); calcium carbonate 10-15 parts (filler, reduces cost and enhances rigidity).

[0097] b. PVC system plastic

[0098] PVCS-1300 PVC resin: 100 parts (high temperature resistant base resin); trioctyl trimellitate (TOTM): 40-45 parts (high temperature resistant plasticizer);

[0099] Tribasic lead sulfate + dibasic lead phosphite: 4-6 parts (composite stabilizer, improves thermal stability);

[0100] Calcined clay (300 mesh): 20-25 parts (filler, enhances insulation and heat resistance); PBST lubricant: 1-2 parts (optimizes processing fluidity); bisphenol A: 0.3-0.5 parts (antioxidant, delays oxidative degradation).

[0101] c. Silane cross-linked polyethylene (XLPE) system plastics

[0102] Low-density polyethylene (LDPE): 100 parts; silane coupling agent (such as vinyltrimethoxysilane): 1-2 parts (crosslinking agent, initiating crosslinking reaction); dicumyl peroxide (DCP): 0.02-0.2 parts (catalyst, promoting crosslinking); antioxidant (such as hindered phenols): 0.1-0.3 parts (to prevent thermal oxidation during processing);

[0103] d. Peroxide cross-linked polyethylene (XLPE) system plastics

[0104] High-density polyethylene (HDPE): 100 parts (high mechanical strength substrate); dicumyl peroxide (DCP): 1.5-2 parts (cross-linking agent, decomposes at high temperature to induce cross-linking); carbon black: 2-3 parts (light stabilizer, shielding ultraviolet rays); aluminum hydroxide (Al(OH)3): 10-15 parts (flame retardant, improves fire resistance).

[0105] Based on general knowledge of plastic molding, those skilled in the art can easily understand how to obtain a cable outer sheath material from a basic plastic component and a refractory filler. This can be illustrated, but not limited to, by taking high-density polyethylene and ethylene-vinyl acetate copolymer as the basic plastic components. The process for obtaining the cable outer sheath material is as follows:

[0106] S1. Add high-density polyethylene and ethylene-vinyl acetate copolymer into a stirring mixer, then add 80% of plasticizer dibutyl phthalate, heat to 75°C and mix for 5 minutes; S2. Add some antioxidants such as antioxidant 1076, antioxidant 168, titanate coupling agent TMC-TTS, the above-mentioned refractory filler and the remaining plasticizer dibutyl phthalate to the mixture in step (1), then heat to 100°C and mix for 10 minutes; S3. Put the mixture in step (2) into a twin-screw extruder for granulation, and the processing temperature is 150-180°C to obtain a cable material.

[0107] When the basic plastic component is of other types, at least the temperature, time and corresponding cross-linking agent in S1, S2 and S3 are adaptively adjusted.

[0108] Fire-resistant alumina fiber-containing cables

[0109] The fire-resistant alumina fiber-containing cable comprises the cable outer sheath material as described above.

[0110] [Implementation process of embodiments and comparative examples]

[0111] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0112] 1. [Manufacturing Example of Refractory Filler Series A]

[0113] S1. Add an appropriate amount of KH-550 and water to the water tank of an ultrasonic oscillating water bath (Bandelin SONOSHAKE, Germany). When the mixture is adjusted to 8°C, add alumina fibers to the water tank and ultrasonically disperse for 30 minutes. Filter and dry at 120°C to obtain modified alumina fibers.

[0114] S2. A mixture of deionized water, ethanol, and propylene glycol in a volume ratio of 3:1:0.2 is placed in a flask, an appropriate amount of phase change material is weighed and placed in the flask, and the phase change material is mechanically stirred sufficiently to ensure that the concentration of the phase change material dispersion in the glass bottle reaches a predetermined concentration.

[0115] S3. Transfer the phase change material dispersion in the flask to the water tank of an ultrasonic oscillating water bath (produced by Bandelin SONOSHAKE, Germany), add the above-mentioned modified alumina fiber into the water tank, start ultrasonic dispersion for 40 minutes, filter, and air-dry at 80 degrees Celsius.

[0116] A series of refractory fillers A1-A8 were prepared by using the above operations described in "[Example of Manufacturing Refractory Fillers]" of this section and combining them with the process conditions in Table 1.

[0117] 2. [Manufacturing Example of Refractory Filler Series B]

[0118] Based on the above “Example of manufacturing refractory filler series A]”, the alumina fiber operation S1 is omitted.

[0119] A series of refractory fillers B1 was prepared by using the above operations described in "[Example of Manufacturing Refractory Filler Series B]" of this section and combining the process conditions in Table 1.

[0120] 3. [Manufacturing Example 1 of Cable Outer Sheath Material]

[0121] (Base plastic is high-density polyethylene and ethylene-vinyl acetate copolymer)

[0122] S1. Ratio of raw materials: in parts by weight, 80 parts of high-density polyethylene, 15 parts of ethylene-vinyl acetate copolymer, 13 parts of dibutyl phthalate, 0.3 parts of antioxidant 1076 and antioxidant 168 (the mass ratio of the two is 1:1), 2.6 parts of titanate coupling agent TMC-TTS and an appropriate amount of refractory filler (as described in the above "[Manufacturing Example of Refractory Filler Series A]", "[Manufacturing Example of Refractory Filler Series B]").

[0123] S2. Add high-density polyethylene and ethylene-vinyl acetate copolymer into a stirring mixer, then add 80% of plasticizer dibutyl phthalate, raise the temperature to 75° C. and mix for 5 minutes.

[0124] S3, adding some antioxidants such as antioxidant 1076, antioxidant 168, titanate coupling agent TMC-TTS, refractory filler and the remaining plasticizer dibutyl phthalate to the mixture in S1, then heating to 100°C and mixing for 10 minutes;

[0125] S4. The mixture in S3 is put into a twin-screw extruder for granulation at a processing temperature of 150-180°C.

[0126] A series of cable outer sheath materials were prepared by using the above operations described in "Example 1 for the manufacture of cable outer sheath materials" of this section and combining them with the process conditions in Table 2.

[0127] 4. [Example 2 of manufacturing cable outer sheath material]

[0128] (The base plastic is PVDF plastic)

[0129] By weight, 100 parts of PVDF plastic and 9 parts of solubilizer (DCP, DMF, MAH in a mass ratio of 1:1:1) were mixed in a high-speed mixer for 10 minutes to obtain a mixture. The mixture was transferred to a twin-screw extruder and extruded to obtain a molten material. The extrusion temperature of the twin-screw extruder was 180-220°C and the screw speed was 500 rpm. The molten material was extruded into an impregnation head, and an appropriate amount of refractory filler (such as the above "[Refractory Filler Manufacturing Example Series A]" and "[Refractory Filler Manufacturing Example Series B]") was added to the mixture in the impregnation head and impregnated at 220°C. After 20 minutes, an impregnation material was obtained. The impregnation material was cooled with water and then added to an injection molding machine for injection molding.

[0130] A series of cable outer sheath materials were prepared by using the above operations in "3. [Manufacturing Example of Cable Outer Sheath Materials]" of this section and combining the process conditions in Table 2.

[0131] [Comparative example of cable sheath materials]

[0132] Based on “3. [Manufacturing example of cable outer sheath material]”, the refractory filler is changed to “phase change material and alumina fiber” and the total mass of the phase change material and alumina fiber remains the same as that of the refractory filler.

[0133] A series of cable outer sheath materials were prepared by using the above operations described in "[Manufacturing Example of Cable Outer Sheath Materials]" of this section and combining them with the process conditions in Table 2.

[0134] Table 1 Process conditions of refractory filler

[0135]

[0136] Table 2 Process conditions of cable outer sheath materials

[0137]

[0138]

[0139]

evaluate

[0140] The following evaluations were performed on the cable outer sheath materials of each embodiment and comparative example prepared according to Table 1:

[0141] [Tensile strength]

[0142] The test was carried out in accordance with GB / T 1040.5-2008, Determination of tensile properties of plastics Part 5: Test conditions for unidirectional fiber reinforced composites.

[0143] [Fire resistance]

[0144] The test is carried out in accordance with BS 6387:2003, Fire resistance test methods for cables to maintain line integrity under fire conditions.

[0145] The test is carried out in accordance with BS 8497: 2008 (R2015), Fire resistance test methods for cables to maintain line integrity under fire conditions.

[0146] Table 3 Evaluation results

[0147] BS6387 fire resistance test BS8497 fire resistance test Tensile strength / Mpa Elongation at break / % Example 1 No breakdown No breakdown 45 280 Example 2 No breakdown No breakdown 43 270 Example 3 No breakdown No breakdown 42 260 Example 4 No breakdown No breakdown 58 300 Example 5 No breakdown No breakdown 51 270 Example 6 No breakdown No breakdown 40 240 Example 7 No breakdown No breakdown 34 210 Example 8 No breakdown No breakdown 36 220 Example 9 No breakdown No breakdown 37 230 Example 10 No breakdown No breakdown 38 240 Example 11 No breakdown No breakdown 39 250 Example 12 No breakdown No breakdown 40 250 Example 13 No breakdown No breakdown 31 200 Comparative Example 1 breakdown breakdown 33 210 Comparative Example 2 breakdown breakdown 50 270

[0148] As can be seen in Table 3, Example 1 significantly outperforms Comparative Example 1 in terms of refractory performance, demonstrating the technical contribution of the phase change material of the present application loaded on alumina fibers to refractory performance. Example 5 significantly outperforms Comparative Example 2 in terms of refractory performance, demonstrating the technical contribution of the phase change material of the present application loaded on alumina fibers to refractory performance. This also confirms that the type of base plastic has no effect on the refractory performance of refractory materials with phase change components loaded on alumina fibers.

[0149] The fire resistance of Example 1 is significantly better than that of Example 5 and Example 13, which shows the technical contribution of the activation treatment of alumina fiber to the fire resistance of the present application.

[0150] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A fire-resistant alumina fiber-containing cable outer sheath material, characterized in that: comprising a basic plastic component and a refractory filler added to the basic plastic component; Wherein, the refractory filler is formed by phase change material loaded on alumina fiber.

2. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The phase change material is a water-bound inorganic salt phase change material.

3. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: Methods for loading phase change materials on alumina fibers include: A1. Provide a phase change material dispersion; A2. Immersing the alumina fiber in a phase change material dispersion; A3. Dry the impregnated alumina fibers.

4. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 3, characterized in that: The concentration of the phase change material dispersion is 3-16 wt %, the immersion time is 15-40 min, and the immersion is carried out under ultrasonic dispersion.

5. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 3, characterized in that: Prior to A2, methods for loading phase change materials onto alumina fibers also included activating the alumina fibers; The activation treatment selects at least one of the following operation items: Plasma treatment under inert atmosphere; Immersed in acid-base regulating solution; Dipping in silicone coupling agent.

6. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The loading amount of the phase change material is 4-23 wt % based on the weight of the alumina fiber.

7. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The addition amount of the refractory filler is 6-18 wt % based on the weight of the basic plastic component.

8. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The aspect ratio of the alumina fiber is 6-13.

9. The fire-resistant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The porosity of the alumina fiber is 75-85%.

10. A fire-resistant cable containing alumina fibers, characterized in that: The invention comprises the fire-resistant alumina fiber-containing cable outer sheath material as claimed in any one of claims 1 to 9.

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