Flame-retardant alumina fiber-containing cable outer sheath material

Abstract

The invention discloses a flame-retardant alumina fiber-containing cable outer sheath material, the cable outer sheath material comprises a basic plastic component and a flame-retardant filler added into the basic plastic component, and the flame-retardant filler is formed by loading a metal hydroxide flame retardant on alumina fibers; the loading mode of the flame-retardant filler is a dipping precipitation reaction method. According to the cable outer sheath material provided by the invention, after the aluminum oxide fibers are loaded with the metal hydroxide flame retardant, the aluminum oxide fibers have relatively good thermal conductivity to ambient temperature, and the aluminum oxide fibers conduct heat to the metal hydroxide flame retardant, so that the metal hydroxide flame retardant can play a role in flame retardance in a heat absorption effect way; therefore, the flame retardance of the outer protective layer is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of cables, and in particular, to a flame-retardant alumina fiber-containing cable outer sheath material. Background Art

[0002] In recent years, with the frequent occurrence of high-voltage power cable fire accidents, the fire resistance problem of wire and cable has gradually attracted attention. Therefore, in recent years, flame-retardant cable materials have been increasingly widely used. It is a multi-component composite material based on polyethylene resin and other materials, with various additives added. Due to its excellent mechanical properties, good weather resistance, excellent electrical insulation properties, easy processing, and low cost, it is widely used as the insulation and sheath materials for wire and cable.

[0003] In the related art, the flame-retardant performance of the cable outer sheath material needs to be improved. Summary of the Invention

[0004]

Problems to be Solved

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, an object of the present application is to provide a flame-retardant alumina fiber-containing cable outer sheath material and a cable, so as to better improve the flame-retardant performance.

[0006]

Means for Solving the Problems

[0007] In the related art, in order to improve the flame-retardant performance of the cable outer sheath, some conventional flame-retardant fillers are usually added in combination or specifically selected, such as halogen flame retardants, metal hydroxide flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, silicon-based flame retardants, or intumescent flame retardants, etc. Generally, the fire resistance methods of these flame-retardant fillers are passive, that is, the high-temperature resistance of the filler itself is used to endow the cable outer sheath with a certain flame-retardant performance, and the flame-retardant performance brought by these methods is relatively limited.

[0008] The inventors of the present application have conducted repeated in-depth studies to solve the above problems and realized that, based on this awareness, it is creatively found that after loading a metal hydroxide flame retardant on alumina fiber, the alumina fiber itself has good thermal conductivity to the surrounding temperature, and the alumina fiber conducts heat to the metal hydroxide flame retardant, which is beneficial to the flame retardancy of the metal hydroxide flame retardant through the endothermic effect, thereby further improving the flame-retardant performance of the outer sheath. Thus, the present invention is completed.

[0009] On the one hand, the present application provides a flame-retardant alumina fiber-containing cable outer sheath material, which comprises a base plastic component and a flame-retardant filler added to the base plastic component, and the flame-retardant filler is formed by loading a metal hydroxide flame retardant on alumina fiber;

[0010] The method of loading a metal hydroxide flame retardant onto alumina fibers includes:

[0011] A1. Providing a precursor solution containing soluble metal ions, where the soluble metal ions are the metal ions corresponding to the metal hydroxide flame retardant;

[0012] A2. After the alumina fibers are immersed in the precursor solution, adding an alkali solution to the precursor solution to cause a precipitation reaction of the soluble metal ions;

[0013] A3. Separating the solid component from the precursor solution after A2 to obtain alumina fibers loaded with the hydroxide flame retardant.

[0014] In any embodiment, the metal hydroxide flame retardant is aluminum hydroxide.

[0015] In any embodiment, before the operation of adding the alkali solution to the precursor solution, A2 further includes: after the alumina fibers are immersed in the precursor solution, placing the precursor solution under microwave radiation.

[0016] In any embodiment, the power of the microwave radiation is 500 - 700 watts, and the radiation time is 5 - 20 minutes.

[0017] In any embodiment, after A3, the method of loading a metal hydroxide flame retardant onto alumina fibers further includes:

[0018] A4. Calcining the alumina fibers loaded with the metal hydroxide flame retardant at 200 - 300 °C.

[0019] In any embodiment, the calcination time is 2 - 5 hours.

[0020] In any embodiment, before A2, the method of loading a metal hydroxide flame retardant onto alumina fibers further includes activating the alumina fibers;

[0021] The activation treatment selects at least one of the following operation items:

[0022] Immersing in an acid-base adjusting solution;

[0023] Immersing in a silane coupling agent.

[0024] In any embodiment, the addition amount of the flame retardant filler is 11 - 38 wt% based on the weight of the base plastic component.

[0025] In any embodiment, the aspect ratio of the flame retardant filler is 6 - 13.

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

[0027]

Invention Effect

[0028] The flame-retardant alumina fiber-containing cable outer sheath material provided by the present application has high flame-retardant performance. Specific Embodiments

[0029] Hereinafter, the embodiments of the present application will be specifically described in detail. However, there may be cases where unnecessary details are omitted. For example, there are cases where the detailed description of well-known matters and the repeated description of actually identical structures are omitted. This is to prevent 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 recited in the claims. The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when a certain parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0031] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0032] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), indicating that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

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

[0034] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": 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 that characterize the cable outer sheath other than its shape or structure, and it encompasses both the raw materials (starting materials) of the cable outer sheath and the formed materials obtained by processing the raw materials through conventional plastic processing.

[0037] The specifically disclosed flame-retardant alumina fiber-containing cable outer sheath material contains a base plastic component and a flame-retardant filler added to the base plastic component; wherein, the flame-retardant filler is formed by loading a metal hydroxide flame retardant on alumina fibers.

[0038] Regarding the addition amount of the flame retardant filler, those skilled in the art can obtain it through conventional tests based on the flame retardant performance and other performance requirements to be pursued, such as mechanical properties and aging resistance. The appropriate but non-limiting addition amount of the flame retardant filler is 11-38 wt% based on the weight of the alumina fiber. Exemplary addition amounts are 11.5-38 wt%, 12-38 wt%, 13-38 wt%, 14-38 wt%, 15-38 wt%, 16-38 wt%, 18-38 wt%, 20-38 wt%, 22-38 wt%, 23-38 wt%, 25-38 wt%, 28-38 wt%, 29-38 wt%, 32-38 wt%, 34-38 wt%, 36-38 wt%, 11-37.5 wt%, 11-37 wt%, 11-36 wt%, 11-35 wt%, 11-34 wt%, 11-33 wt%, 11-32 wt%, 11-30 wt%, 11-29 wt%, 11-27 wt%, 11-25 wt%, 11-23 wt%, 11-21 wt%, 11-20 wt%, 11-18 wt%, 11-17 wt%, 11-16 wt%, 11-14 wt%, 11-13 wt%, etc.

[0039] If the addition amount of the flame retardant filler is too small, the flame retardant performance of the cable outer sheath will be reduced; if the addition amount is too large, the mechanical properties of the cable (such as fracture resistance and toughness) will be damaged.

[0040]

Alumina fiber

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

[0042] The appropriate but non-limiting aspect ratio of the alumina fiber is 6-13, and can be exemplified as: 6.2-13, 6.5-13,

[0043] 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,

[0044] 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 the mechanical properties and flame retardant performance.

[0045] The appropriate but non-limiting pore rate of the alumina fiber is 75-85%, and can be exemplified as: 75.5-85%,

[0046] 76 - 85%, 78 - 85%, 80 - 85%, 82 - 85%, 75 - 84.5%, 75 - 84%, 75 - 83%, 75 - 82%,

[0047] 75 - 81%, 75 - 80%, 75 - 78%, 75 - 77%, etc. The pore size ratio within this specific range can better balance the mechanical properties and flame retardancy. Moreover, the pore size ratio level affects the thermal conductivity of alumina fibers, that is, the higher the pore size ratio, the smaller the thermal conductivity may be, and the stronger the physical adsorption force. And the thermal conductivity may be directly related to the overall flame retardancy effect, and the physical adsorption force is related to the impregnation effect of alumina fibers (described later).

[0048] It should be noted that the aspect ratio or pore size ratio of the above - mentioned range of alumina fibers is within the conventional level of alumina, that is, alumina fibers obtained by conventional methods all have an aspect ratio or pore size ratio. If the mature commercial channels cannot accurately meet the requirements of the above - mentioned aspect ratio or pore size ratio, it can also be prepared by conventional methods.

[0049] Conventional preparation methods of alumina fibers can adopt sol - gel method, melt spinning method, chemical vapor deposition (CVD), electrospinning method, impregnation - sintering method, co - precipitation method, etc. The process of the sol - gel method is to dissolve aluminum alkoxide or aluminum salt in an organic solvent to form a homogeneous solution (sol), and then hydrolysis and polymerization reactions occur under certain conditions to transform into a gel - like substance. After the gel is dried to remove the solvent, a precursor fiber is obtained, and then it is converted into alumina fiber by high - temperature calcination.

[0050] The melt spinning method is to heat a mixture containing alumina and other additives to above the melting point to form a melt, then extrude it through a fine hole into filaments, and quickly cool and solidify it into shape. The fibers are further heat - treated to remove impurities and improve crystallinity. Chemical vapor deposition (CVD) is to react an aluminum - containing gas (such as aluminum trichloride vapor) with oxygen or other oxidants at a specific temperature to deposit and form an alumina film or fiber on the substrate surface. The microstructure and properties of the fibers can be regulated by changing process parameters. The electrospinning method is to use a charged jet stretched and refined by a high - voltage electric field for a polymer solution or melt to form nano - scale fibers. For alumina fibers, usually a spinning solution containing an alumina precursor is first prepared, and after spinning, it is sintered to be converted into alumina fibers. The impregnation - sintering method is to soak a pre - fabricated organic or inorganic fiber skeleton in a solution containing an aluminum source, so that aluminum ions penetrate into the fiber interior. After drying, it is sintered under a high - temperature environment, so that the aluminum source is converted into alumina and fills the fiber gaps or coats the fiber surface. The co - precipitation method is to add a precipitant to a solution containing aluminum ions to promote the formation of aluminum hydroxide precipitation, and then filter, wash and dry to obtain aluminum hydroxide powder. The aluminum hydroxide powder decomposes at high temperature to be converted into alumina, and can be made into fiber form through subsequent processing.

[0051]

Metal hydroxide flame retardant

[0052] It is well known to those skilled in the art that hydroxide flame retardants can include aluminum hydroxide (ATH) and magnesium hydroxide (MDH), which provide flame retardant properties through physical processes rather than chemical reactions. Such flame retardants mainly achieve flame retardant effects through the following mechanisms:

[0053] a. Endothermic effect: When the temperature rises, the hydroxide will undergo a decomposition reaction, absorbing a large amount of heat. For example, aluminum hydroxide begins to decompose into alumina and water vapor at about 200 degrees Celsius, and the reaction formula is as follows:

[0054] 2Al(OH)3 → Al2O3 + 3H2O;

[0055] A large amount of heat is consumed in this process, thereby reducing the surface temperature of the polymer material and slowing down the combustion rate.

[0056] b. Diluting the concentration of combustible gases: The water generated by decomposition evaporates into steam, which dilutes oxygen and combustible gases in the flame area, reducing the amount of fuel required for combustion and thus inhibiting the spread of the flame.

[0057] c. Forming a protective layer: The decomposed metal oxides (such as alumina or magnesia) are deposited on the surface of the polymer, forming a heat-insulating and oxygen-insulating barrier that prevents the internal material from further decomposing and burning due to heat.

[0058] d. Reducing smoke generation: Due to its cooling effect and isolation function, the hydroxide can also reduce the generation of smoke and other toxic gases, improving fire safety while also reducing the impact on the environment.

[0059] Based on the flame retardant principle of the endothermic effect in the above a method, the applicant unexpectedly found that when the metal hydroxide flame retardant is loaded on alumina fiber, due to the inherent thermal conductivity of the alumina fiber, the heat around it can be conducted to the metal hydroxide flame retardant, and the metal hydroxide flame retardant can absorb the heat better, with higher efficiency than when the metal hydroxide flame retardant uses other media such as air or basic plastic components, thereby promoting the overall flame retardant effect.

[0060] Within the conventional range of metal hydroxide flame retardants, the inventors unexpectedly found that aluminum hydroxide flame retardant has better load-bearing capacity with alumina fibers compared to other hydroxide flame retardants. The reason may be that since the main component of alumina fibers is alumina, theoretically, aluminum hydroxide may be more likely to be converted into alumina through dehydration reaction under appropriate conditions due to its same metal component as alumina, thus forming stronger chemical bonding or tighter physical adsorption on the surface of alumina fibers. This similarity may result in better affinity and adhesion between metal hydroxides and alumina fibers. Therefore, as a more suitable metal hydroxide flame retardant, aluminum hydroxide is preferred.

[0061]

Flame Retardant Filler Obtained by Loading Metal Hydroxide Flame Retardant on Alumina Fibers

[0062] As applicable in the text, "loading of metal hydroxide flame retardant on alumina fibers" refers to the attachment state formed by the metal hydroxide flame retardant through physical actions (such as molecular adsorption force, electrostatic force, molecular hydrogen bond, or van der Waals force) and / or chemical bonds (such as bonding between active groups like carboxyl group and hydroxyl group).

[0063] The method for loading the metal hydroxide flame retardant on alumina fibers is the impregnation precipitation method. The principle of this method is that alumina fibers are impregnated in a solution containing soluble metal salts, and alkali is added to make the soluble metal form a precipitate of hydroxide, so as to achieve the purpose of loading the hydroxide on the surface of alumina fibers.

[0064] The specific steps of the above impregnation precipitation method include:

[0065] A1. Provide a precursor solution containing soluble metal ions, where the soluble metal ions are the metal ions corresponding to the metal hydroxide flame retardant;

[0066] A2. After the alumina fibers are impregnated in the precursor solution, add an alkali solution to the precursor solution to cause the soluble metal ions to undergo a precipitation reaction;

[0067] A3. Separate the solid component from the precursor solution after step A2, which is the alumina fibers loaded with the hydroxide flame retardant.

[0068] Here in A1, the source of the soluble metal ions can be aluminum ions or magnesium ions. The salts of aluminum ions or magnesium ions are other water-soluble substances such as aluminum chloride or aluminum nitrate. The mass concentration of the soluble metal ions in the precursor solution can be 1-5 wt%, and can be exemplified as 1.2-5 wt%, 1.5-5 wt%, 2-5 wt%, 2.2-5 wt%, 2.5-5 wt%, 3-5 wt%, 3.5-5 wt%, 4-5 wt%, 4.5-5 wt%, 1.2-5 wt%, 1-4.5 wt%, 1-4 wt%, 1-3.8 wt%, 1-3.5 wt%, 1-3 wt%, 1-2.8 wt%, 1-2.5 wt%, 1-2 wt%, 1-1.5 wt%, etc. If it exceeds this range, agglomeration of the generated hydroxide may occur; if it is lower than this range, there may be too little hydroxide flame retardant loaded on the alumina fiber, affecting the flame retardant effect.

[0069] Alumina is impregnated in the precursor solution. The soluble metal ions do not simply diffuse to the alumina fiber interface depending on the concentration difference, but more rely on the basic physical adsorption force due to the porous structure of the alumina fiber. This adsorption force can ensure that even in the precursor solution at a relatively low concentration level as described above, the soluble metal ions can basically adhere to the surface of the alumina fiber satisfactorily, thereby ensuring that the amount of hydroxide flame retardant loaded on the surface of the alumina fiber is basically satisfactory.

[0070] The solvent used in the precursor solution can be water or a mixture of water and a hydrophilic medium, such as C1-4 alcohols, C1-4 amine solvents, DMSO and the like. As for the dispersion process of the metal hydroxide flame retardant, it can be achieved by general experimental capabilities, with the help of mechanical stirring, ultrasonic dispersion or adding a co-solvent, etc. Of course, the implementation effect of this technical solution does not specifically depend on the dispersion uniformity of the metal hydroxide flame retardant dispersion. The adverse effects brought by the heterogeneous state can be compensated by assisting ultrasonic dispersion in the subsequent step A2 process.

[0071] Here in A2, before adding the alkali solution, the impregnation process of the alumina fiber can be very short so that the impregnation of alumina is only regarded as an immersion operation. Although the impregnation time is relatively short, the physical adsorption of the alumina fiber during the subsequent precipitation reaction can maintain the basic amount of soluble metal ions attached to its surface to achieve a basically satisfactory precipitation effect. Of course, the impregnation process of the alumina fiber can also be in a state of maintaining a sufficient time, such as 15-60 min. If the impregnation of the alumina fiber is controlled at a longer time level here, the subsequent precipitation reaction time can be correspondingly reduced. If the impregnation of the alumina fiber is very short, the subsequent precipitation reaction time should be ensured to be at a longer level.

[0072] Here in A2, the alkaline solution can be in an easily conceivable form, such as strong alkalis represented by sodium hydroxide and potassium hydroxide or weak alkalis represented by ammonia water. Its concentration can be exemplified as follows: for analogues of sodium hydroxide and potassium hydroxide, the concentration can be 1 - 5 wt%; for ammonia water, the concentration can be 25 - 28%.

[0073] The addition amount of the alkaline solution is not particularly limited. For example, the addition amount of the alkaline solution is to maintain the pH of the reaction system at 8 - 10 to ensure the full reaction of soluble metal ions.

[0074] The precipitation reaction time is preferably 30 - 180 min, and can be exemplified as 32 - 180 min, 35 - 180 min, 40 - 180 min, 45 - 180 min, 50 - 180 min, 60 - 180 min, 70 - 180 min, 75 - 180 min, 80 - 180 min, 90 - 180 min, 100 - 180 min, 110 - 180 min, 120 - 180 min, 130 - 180 min, 140 - 180 min, 150 - 180 min, 160 - 180 min, 170 - 180 min, 30 - 175 min, 30 - 170 min, 30 - 160 min, 30 - 150 min, 30 - 140 min, 30 - 130 min, 30 - 120 min, 30 - 115 min, 30 - 100 min, 30 - 90 min, 30 - 80 min, 30 - 70 min, 30 - 60 min, 30 - 50 min.

[0075] The temperature of the precipitation reaction can be 20 - 60 °C, which has no particularly obvious effect on the precipitation reaction effect.

[0076] A suitable but non - restrictive implementation method is that before the operation of adding the alkaline solution to the precursor solution, A2 further includes: after the alumina fiber is impregnated in the precursor solution, the precursor solution is placed under microwave radiation. Thus, for the purpose of microwave radiation, it can promote the hydrolysis of soluble metal ions and their deposition on the surface of the alumina fiber. Of course, through the thermal effect of microwave radiation or by promoting the molecular vibration effect of the precursor solution, it can also accelerate the attachment of soluble metal ions to the surface of the alumina fiber to be beneficial to the precipitation reaction effect.

[0077] Here, the power of microwave radiation is preferably 500 to 700 watts, and can be exemplified as 520 to 700 watts, 530 to 700 watts, 550 to 700 watts, 600 to 700 watts, 650 to 700 watts, 500 to 680 watts, 500 to 650 watts, 500 to 600 watts, 500 to 550 watts, etc.; the radiation time is 5 to 20 minutes, and can be exemplified as 6 to 20 minutes, 8 to 20 minutes, 10 to 20 minutes, 12 to 20 minutes, 15 to 20 minutes, 5 to 18 minutes, 5 to 15 minutes, 5 to 13 minutes, 5 to 10 minutes, 5 to 8 minutes, etc.

[0078] Here, after separating the hydroxide product from the precipitation reaction product solution in A3, it can also be fully dried, for example, dried at 60 to 80 °C for 4 to 8 hours. Of course, before drying, it can also be washed with deionized water.

[0079] Suitable but non-limiting specific examples. After A3, the ways to load the metal hydroxide flame retardant on the alumina fiber also include:

[0080] A4. Calcining the alumina fiber loaded with the metal hydroxide flame retardant at 200 to 300 °C, and the calcination temperature can be exemplified as 210 to 300 °C, 220 to 300 °C, 250 to 300 °C, 270 to 300 °C, 280 to 300 °C, 200 to 290 °C, 200 to 280 °C, 200 to 270 °C, 200 to 260 °C, 200 to 250 °C, 200 to 230 °C, etc.

[0081] Here, the purpose of calcination in this creation sold to you is to enhance the bonding strength with the fiber matrix while retaining part of the aluminum hydroxide to maintain the flame retardant or adsorption function.

[0082] Based on the above calcination temperature, the calcination time is preferably selected as 2 - 5 hours, and can be exemplified as 2.25 - 5 hours, 2.5 - 5 hours, 3 - 5 hours, 3.5 - 5 hours, 4 - 5 hours, 2 - 4.5 hours, 2 - 4 hours, 2 - 3 hours, etc.

[0083] As discussed above, the more suitable metal hydroxide flame retardant is the aluminum hydroxide flame retardant. This metal hydroxide flame retardant can also achieve the purpose that the hydrated inorganic salt metal hydroxide flame retardant and the alumina fiber have high molecular compatibility, avoiding poor adhesion between the metal hydroxide flame retardant and the alumina fiber. However, in order to further improve the adhesion between the metal hydroxide flame retardant and the alumina fiber, before A2, the ways to load the metal hydroxide flame retardant on the alumina fiber also include activating the alumina fiber;

[0084] The above activation treatment selects at least one of the following operation items:

[0085] Impregnate in the acid-base regulating solution;

[0086] Impregnate in the siloxane coupling agent.

[0087] The purpose of the above impregnation in the acid-base regulating solution is to create active groups on the surface of the alumina fiber through the hydrogen protons provided by the acid or the hydroxide ions provided by the alkali solution, so as to form chemical or physical interactions with the hydrogen-containing groups in the metal hydroxide flame retardant, and thus achieve the purpose of providing adhesion. For the acid-base solution, conventional non-oxidizing acids such as dilute sulfuric acid and dilute hydrochloric acid can be used; the alkali solution can be sodium hydroxide, potassium hydroxide, etc. The impregnation time is adjusted according to conventional needs.

[0088] In the item of impregnation in the above siloxane coupling agent, its purpose is: to form a bridging effect between the metal hydroxide flame retardant and the alumina fiber through the siloxane coupling agent. Conventional siloxane coupling agents such as KH-550, KH-560, KH-570, etc. can be used.

[0089] As previously discussed, in the implementation method of achieving loading by the impregnation method, the concentration of the dispersion liquid, the impregnation time, and the impregnation carried out under the impregnation auxiliary conditions can obtain a more suitable loading amount of the metal hydroxide flame retardant. As a suitable but non-limiting loading amount, it is 4-23 wt% based on the weight of the alumina fiber, and can be demonstrated as 4.2-23 wt%, 4.5-23 wt%, 5-23 wt%, 5.5-23 wt%, 6-23 wt%, 6.5-23 wt%, 7-23 wt%, 8-23 wt%, 9-23 wt%, 10-23 wt%, 11-23 wt%, 12-23 wt%, 15-23 wt%, 18-23 wt%, 20-23 wt%, 4-22 wt%, 4-21 wt%, 4-20 wt%, 4-19 wt%, 4-18 wt%, 4-17 wt%, 4-16 wt%, 4-15 wt%, 4-14 wt%, 4-13 wt%, 4-12 wt%, 4-10 wt%, 4-9 wt%, 4-8 wt%, 4-7 wt%, 4-6 wt%, etc.

[0090] If the loading amount is too much, it may cause damage to the adhesion effect of the metal hydroxide flame retardant from the alumina fiber, and at the same time, it is not conducive to the alumina fiber to endow the outer protective layer with its basic mechanical properties.

[0091] Those skilled in the art can refer to the existing technologies of the loading amount of porous materials to obtain it. Conventional measurement methods can include, for example, gravimetric analysis, microscopic imaging technology, and GB / T 7714-2018: The porosity test of porous materials in Chinese national standards.

[0092] Here, the principle of the gravimetric analysis method is: measuring the mass difference before and after the material adsorption. Its actual operation process is: first pre-treat the material (remove impurities by drying, high-temperature activation, etc.). Then immerse the material in the medium to be adsorbed (such as water, organic solvents or gases) under controlled temperature and humidity until equilibrium is reached. Remove the residual liquid phase on the surface by centrifugation or vacuum suction. Weighing the mass change is the loading amount.

[0093] Here, the microscopic imaging technology (assisted by qualitative analysis) can be carried out with the help of SEM / TEM electron microscopes and XPS / EDS elemental analyzers. SEM / TEM electron microscopes: Observe the surface morphology and pore distribution of the material to verify the loading uniformity. XPS / EDS: Analyze the chemical composition of the adsorbed species and the influence of surface functional groups, and then obtain the content of the loaded metal hydroxide flame retardant.

[0094]

Base plastic components

[0095] As the base plastic components of this application, any type of plastic used in cables can be adopted, and the type of plastic does not affect the flame retardant performance of the flame retardant filler. Some conventional plastic forms can be cited, such as cross-linked polyethylene (XLPE), high-density polyethylene, polyvinyl chloride, polypropylene, ethylene-vinyl acetate copolymer, fluoroplastics (such as polytetrafluoroethylene (PTFE), perfluoroethyl propylene (FEP)), silicone rubber, ethylene-propylene rubber (EPR), nylon, and so on.

[0096] The types and addition amounts of the conventional processing aids for the cable outer sheath widely known in the art do not play a decisive role in the flame retardant performance of the flame retardant filler of this application. These processing aids can be listed as follows:

[0097] a. Plasticizers, used to improve flexibility and processing fluidity by increasing the distance between plastic molecular chains. Plasticizers typified by phthalates (such as DOP, DINP) and phosphates;

[0098] b. Stabilizers, used to inhibit the decomposition of materials caused by heat, light or oxidation during processing or use, such as the inhibition of hydrogen chloride released by PVC at high temperature. Stabilizers typified by lead salts (lead sulfate) and calcium-zinc composite stabilizers;

[0099] c. Antioxidants, used to delay the oxidative degradation of materials, improve heat resistance and service life. Antioxidants typified by hindered phenols (such as BHT), phosphites and thioesters;

[0100] d. Lubricants, used to reduce the friction between plastics and equipment during processing and improve the surface smoothness. Lubricants typified by stearic acid, paraffin wax, polyethylene wax, etc.;

[0101] e. Fillers, used to reduce costs and improve the rigidity, heat resistance or insulation performance of materials;

[0102] f. Crosslinking agents are used to promote the crosslinking of polyethylene (PE) to form a three-dimensional network structure, improving heat resistance and mechanical strength 35. Typical representatives include dicumyl peroxide (DCP), silane coupling agents, etc.;

[0103] g. Light stabilizers are used to absorb or shield ultraviolet rays and delay the aging of outdoor cables. Typical representatives include carbon black (light shielding agent), benzotriazole ultraviolet absorbers (such as UV327);

[0104] h. Dispersants are used to improve the interfacial bonding between inorganic fillers and the plastic matrix and enhance the filling uniformity. Typical representatives include silane coupling agents and titanate coupling agents;

[0105] i. Antistatic agents are used to prevent electrostatic accumulation by reducing the surface resistance.

[0106] Regarding the specific compositions of the basic plastic components and processing aids, some implementation forms applicable to the above-mentioned flame retardant fillers in this application can be demonstrated as follows:

[0107] a. Polyvinyl chloride (PVC) system plastics

[0108] PVC resin: 100 parts; dioctyl phthalate (DOP): 30 - 40 parts (plasticizer to improve flexibility); tribasic lead sulfate: 4 - 5 parts (stabilizer to inhibit thermal decomposition); stearic acid: 0.5 - 1 part (lubricant to improve processing performance); calcium carbonate 10 - 15 parts (filler to reduce cost and enhance rigidity).

[0109] b. PVC system plastics

[0110] PVCS - 1300 type PVC resin: 100 parts (high-temperature resistant base resin); trioctyl trimellitate (TOTM): 40 - 45 parts (high-temperature resistant plasticizer);

[0111] Tribasic lead sulfate + dibasic lead phosphite: 4 - 6 parts (compound stabilizer to improve thermal stability);

[0112] Calcined clay (300 mesh): 20 - 25 parts (filler to enhance insulation and heat resistance); PBST lubricant: 1 - 2 parts (optimize processing fluidity); bisphenol A: 0.3 - 0.5 part (antioxidant to delay oxidative degradation).

[0113] c. Silane crosslinked polyethylene (XLPE) system plastics

[0114] 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 (catalyst, promoting crosslinking); Antioxidant (such as hindered phenols): 0.1 - 0.3 parts (preventing processing thermal oxidation).

[0115] d. Peroxide-crosslinked polyethylene (XLPE) system plastic

[0116] High-density polyethylene (HDPE): 100 parts (high mechanical strength substrate); Dicumyl peroxide (DCP): 1.5 - 2 parts (crosslinking agent, decomposing at high temperature to initiate crosslinking); Carbon black: 2 - 3 parts (light stabilizer, shielding ultraviolet rays); Aluminum hydroxide (Al(OH)3): 10 - 15 parts (flame retardant, improving flame retardancy).

[0117] According to the general and common knowledge of plastic molding, those skilled in the art can easily obtain the cable outer sheath material from the basic plastic components and flame retardant fillers. By way of demonstration but not limitation, taking high-density polyethylene and ethylene-vinyl acetate copolymer as the basic plastic components as an example. The process of obtaining the cable outer sheath material is as follows:

[0118] S1. Add high-density polyethylene and ethylene-vinyl acetate copolymer into a stirring and mixing machine, then add 80% of the plasticizer dibutyl phthalate, heat up to 75°C and mix for 5 minutes; S2. Add some antioxidants such as antioxidant 1076, antioxidant 168, titanate coupling agent TMC-TTS, the aforementioned flame retardant fillers and the remaining plasticizer dibutyl phthalate into the mixed material in step (1), then heat up to 100°C and mix for 10 minutes; S3. Feed the mixed material in step (2) into a twin-screw extruder for pelletizing, with the processing temperature being 150 - 180°C to obtain the cable material.

[0119] In the case where the basic plastic components are of other types, at least adaptively adjust the temperature, time and corresponding crosslinking agents in S1, S2 and S3.

[0120]

Aluminum oxide fiber-containing cable with flame retardancy

[0121] The above-mentioned aluminum oxide fiber-containing cable with flame retardancy includes the cable outer sheath material as described above.

[0122]

Implementation processes of examples and comparative examples

[0123] The embodiments of the present application will be described below. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, the technologies or conditions described in the literature in this field or the product specifications shall be followed. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchases.

[0124] 1. [Manufacturing Example Series A of Flame Retardant Filler]

[0125] S1. An aqueous solution of KH-550 with a concentration of 1.5 wt% was added into the water tank of an ultrasonic oscillation water bath (produced by Bandelin SONOSHAKE, Germany). When the pH of the mixed solution was adjusted to 8, alumina fibers were added into the water tank and ultrasonic dispersion was carried out for 60 min, followed by filtration and drying at 120 °C to obtain modified alumina fibers.

[0126] S2. An aluminum nitrate or magnesium nitrate solution with a concentration of 10 wt% was transferred into a flask. The modified alumina fibers obtained in S1 were added into the flask, and mechanical stirring was carried out sufficiently to allow aluminum ions to pre-infiltrate the modified alumina fibers. Then, a sodium hydroxide solution was slowly added dropwise into the flask, and the dropping rate was controlled to maintain the pH of the liquid in the flask at 8. The precipitation reaction time was controlled. After the precipitation reaction ended, suction filtration was carried out, and the filter residue was washed. The filter residue was washed with deionized water until neutral, and then dried at 80 °C for 6 hours to obtain the flame retardant filler.

[0127] Using the above operations in this part "[Manufacturing Example of Flame Retardant Filler]" and combining with the process conditions in Table 1, a series of flame retardant fillers A1 - A2 were prepared.

[0128] 2. [Manufacturing Example Series B of Flame Retardant Filler]

[0129] Based on the above "Manufacturing Example Series A of Flame Retardant Filler", S2 was changed to "An aluminum nitrate solution with a concentration of 10 wt% was transferred into a flask. After the modified alumina fibers obtained in S1 were added into the flask, the flask was transferred to In a microwave reactor (preferably Yunpu YP-WH3), control the power of microwave radiation, and keep the microwave radiation time the same as the mechanical stirring time in the previous text "[Manufacturing Example Series A of Flame Retardant Filler]" unchanged. , to allow aluminum ions to pre-infiltrate the modified alumina fibers. Then, a sodium hydroxide solution was slowly added dropwise into the flask, and the dropping rate was controlled to maintain the pH of the liquid in the flask at 8. The precipitation reaction time was controlled. After the precipitation reaction ended, suction filtration was carried out, and the filter residue was washed. The filter residue was washed with deionized water until neutral, and then dried at 80 °C for 6 hours to obtain the flame retardant filler".

[0130] Using the above operations in this part "[Manufacturing Example Series B of Flame Retardant Filler]" and combining with the process conditions in Table 1, a series of flame retardant fillers B1 - B2 were prepared.

[0131] 3. [Manufacturing Example Series C of Flame Retardant Filler]

[0132] Based on the foregoing “Manufacturing Example Series B of Flame Retardant Filler]”, after S2, add the operation of “placing the flame retardant filler obtained in S2 in a muffle furnace and calcining it in a nitrogen atmosphere”.

[0133] Using the above operations in this part “[Manufacturing Example Series B of Flame Retardant Filler]” and combining with the process conditions in Table 1, a series of flame retardant fillers C1-C9 were prepared.

[0134] 4. [Manufacturing Example 1 of Cable Outer Sheath Material]

[0135] (The base plastic is high-density polyethylene and ethylene-vinyl acetate copolymer)

[0136] S1. Mixing raw materials: 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 flame retardant filler (such as the foregoing “[Manufacturing Example Series A of Flame Retardant Filler]” and “[Manufacturing Example Series B of Flame Retardant Filler]”).

[0137] S2. Add high-density polyethylene and ethylene-vinyl acetate copolymer into a stirring mixer, then add 80% of the plasticizer dibutyl phthalate, and raise the temperature to 75°C and mix for 5 minutes.

[0138] S3. Add some such as antioxidant 1076, antioxidant 168, titanate coupling agent TMC-TTS, flame retardant filler and the remaining plasticizer dibutyl phthalate to the mixed material in S1, then raise the temperature to 100°C and mix for 10 minutes;

[0139] S4. Put the mixed material in S3 into a twin-screw extruder for granulation, and the processing temperature is 150-180°C.

[0140] Using the above operations in this part “[Manufacturing Example of Cable Outer Sheath Material]” and combining with the process conditions in Table 2, a series of cable outer sheath materials were prepared.

[0141] 5. [Manufacturing Example 2 of Cable Outer Sheath Material]

[0142] (The base plastic is PVDF plastic)

[0143] By weight, 100 parts of PVDF plastic and 9 parts of solubilizer (DCP, DMF, and MAH with a mass ratio of 1:1:1) are mixed in a high-speed mixer for 10 minutes to obtain a mixed material. The mixed material is transferred to a twin-screw extruder to be extruded into a molten material. The extrusion temperature of the twin-screw extruder is 180 - 220 °C, and the screw speed is 500 rpm. The molten material is extruded into an impregnation head, and an appropriate amount of flame retardant filler (such as the previous "[Manufacturing Example Series A of Flame Retardant Filler]" and "[Manufacturing Example Series B of Flame Retardant Filler]") is added to the mixed material in the impregnation head and impregnated at 220 °C. After 20 minutes, an impregnated material is obtained. The impregnated material is cooled with water and then added to an injection molding machine for injection molding.

[0144] Using the above operations in this part "[Manufacturing Example 2 of Cable Outer Sheath Material]" and combining with the process conditions in Table 2, a series of cable outer sheath materials are prepared.

[0145] [Comparative Example of Cable Outer Sheath Material]

[0146] Based on "[Manufacturing Example 1 of Cable Outer Sheath Material]" and "[Manufacturing Example 2 of Cable Outer Sheath Material]", the flame retardant filler is changed to "metal hydroxide flame retardant and alumina fiber", and the total mass of the metal hydroxide flame retardant and alumina fiber remains the same as that of the flame retardant filler.

[0147] Using the above operations in this part "[Comparative Example of Cable Outer Sheath Material]" and combining with the process conditions in Table 2, a series of cable outer sheath materials are prepared.

[0148] Table 1 Process Conditions of Flame Retardant Filler

[0149]

[0150] Table 2 Process Conditions of Cable Outer Sheath Material

[0151]

[0152]

[0153]

Evaluation

[0154] The cable outer sheath materials of each example and comparative example prepared according to Table 1 are evaluated as follows:

[0155] [Tensile Strength]

[0156] This test is carried out in accordance with "GB / T 1040.5 - 2008, Plastics - Determination of tensile properties - Part 5: Test conditions for unidirectional fiber - reinforced composites".

[0157] [Flame Retardant Performance]

[0158] Implement this test in accordance with "GB 31247-2014 Classification of the burning performance of cables and optical cables".

[0159] Table 3 Evaluation results

[0160]

[0161]

[0162] As can be seen from Table 3, the flame retardancy of Example 1 is significantly better than that of Comparative Example 1 and Comparative Example 2, which shows the technical contribution of the metal hydroxide flame retardant of the present application loaded on alumina fibers to the flame retardancy.

[0163] The flame retardancy of Example 1 is significantly better than that of Example 5 and Example 8, which shows the technical contribution of the calcination treatment process and the alumina fiber activation treatment process of the present application to the flame retardancy.

[0164] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A flame-retardant alumina fiber-containing cable outer sheath material, characterized in that, The invention comprises a basic plastic component and a flame retardant filler added to the basic plastic component, wherein the flame retardant filler is formed by loading a metal hydroxide flame retardant on alumina fiber; Methods for loading the metal hydroxide flame retardant on alumina fibers include: A1. Providing a precursor solution containing soluble metal ions, wherein the soluble metal ions are metal ions corresponding to the metal hydroxide flame retardant; A2. After the alumina fibers are immersed in the precursor solution, an alkali solution is added to the precursor solution to cause a precipitation reaction of the soluble metal ions; A3. The solid component separated from the precipitation reaction product solution after A2 is the alumina fiber loaded with hydroxide flame retardant.

2. The flame retardant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that: The metal hydroxide flame retardant is aluminum hydroxide.

3. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 1, characterized in that, Before the operation of adding alkaline solution into the precursor solution, A2 further includes: after the alumina fibers are immersed in the precursor solution, placing the precursor solution under microwave radiation.

4. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 3, characterized in that The power of microwave radiation is 500 to 700 watts, and the radiation time is 5 to 20 minutes.

5. The flame retardant alumina fiber-containing cable outer sheath material according to claim 4, characterized in that: After A3, the method of loading the metal hydroxide flame retardant on the alumina fiber also includes: A4. Calcine the alumina fiber loaded with the metal hydroxide flame retardant at 200-300°C.

6. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 5, characterized in that, The calcination time is 2-5 hours.

7. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 3, characterized in that, Prior to A2, methods for loading the metal hydroxide flame retardant on the alumina fiber also included activating the alumina fiber; The activation treatment selects at least one of the following operation items: Immerse in acid-base regulating solution; Dipping in silicone coupling agent.

8. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 1, wherein The flame retardant filler is added in an amount of 11-38 wt % based on the weight of the basic plastic component.

9. The flame-retardant alumina fiber-containing cable outer sheath material according to claim 1, wherein The aspect ratio of the alumina fiber is 6-13.

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

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