High-flame-retardant and high-flexibility composite material for cable and preparation method thereof

Abstract

The invention discloses a high-flame-retardant and high-flexibility composite material for a cable and a preparation method thereof, and belongs to the technical field of polymer composite materials. The composite material is composed of methyl vinyl silicone rubber, a hydrogenated styrene-butadiene block copolymer, polyether modified silicone oil, a phosphorus-containing flame retardant, a special flame-retardant synergist and auxiliaries such as a vulcanizing agent, a release agent and an antioxidant. Wherein the flame-retardant synergist is prepared by reacting a zinc ion loaded aminated halloysite nanotube with a phosphorus-nitrogen prepolymer, and has synergistic flame-retardant and enhancing effects. The composite material provided by the invention has a vertical combustion grade of UL94 V-0, an oxygen index of 36.8%-39.3%, a Shore A hardness of 40-45 and an elongation at break of 276%-296%, has excellent flame retardance, flexibility, smoke suppression and mechanical stability, is suitable for insulation and sheaths of cables in the fields of new energy, rail transit, aerospace and the like, and has wide application prospects. The technical problem that flame retardance and flexibility of a traditional material are difficult to consider at the same time is solved.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material technology, specifically, it relates to a highly flame-retardant and highly flexible composite material for cables and its preparation method. Background Technology

[0002] With the rapid development of new energy (such as electric vehicles and photovoltaic power generation), rail transportation, aerospace and high-end equipment manufacturing, stringent requirements have been placed on the performance of supporting cables. These cables not only need to have excellent flame retardant, smoke suppression and non-toxic properties under extreme conditions such as high temperature and short circuit to prevent the spread of fire, but also need to have high flexibility, bending resistance and torsion resistance to adapt to complex and narrow wiring spaces and dynamic laying environments.

[0003] Currently, commonly used cable insulation and sheathing materials, such as polyvinyl chloride (PVC), cross-linked polyethylene (XLPE), and certain flame-retardant rubbers, often have the following problems: 1) When traditional flame-retardant materials (such as PVC with high filler aluminum hydroxide / magnesium) achieve a sufficient flame-retardant rating, the material hardness increases significantly, while the flexibility and elongation are severely degraded. 2) Some inherently soft materials (such as ordinary silicone rubber and certain thermoplastic polyurethanes) have low limiting oxygen index (LOI) and their vertical flammability rating is difficult to meet high standards such as UL94 V-0. They require a large amount of flame retardant to be added, which in turn damages their processability and mechanical properties. 3) The flame retardant has poor compatibility with the matrix and is prone to migration and precipitation, which affects the long-term flame retardant stability and the feel of the material.

[0004] Therefore, developing a composite material for cables that can simultaneously achieve extremely high flame retardancy and excellent flexibility, while maintaining stable overall performance, has become a key technical challenge that urgently needs to be addressed in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite material for cables that simultaneously possesses high flame retardancy, low hardness, high elongation, high flexibility, excellent smoke suppression performance, good compatibility of components, and long-term stability.

[0006] To achieve the above objectives, the present invention discloses the following technical solutions: In a first aspect, the present invention provides a highly flame-retardant and highly flexible composite material for cables, wherein the composite material contains the following components in parts by weight: 100-150 parts of methyl vinyl silicone rubber, 25-30 parts of hydrogenated styrene-butadiene block copolymer, 5-10 parts of polyether-modified silicone oil, 50-70 parts of flame retardant, 10-15 parts of flame retardant synergist, 2-5 parts of vulcanizing agent, 2-3 parts of release agent, and 1-5 parts of antioxidant; The flame retardant is a phosphorus-containing flame retardant; The flame retardant synergist is prepared by the following method: Step 1: Dissolve water-soluble zinc salt in water to obtain a zinc ion-containing solution, then mix the solution with aminated halloysite nanotubes and stir at 50-70℃ for 6-10 hours. After the mixture is finished, filter and collect the solid, and dry the solid to obtain Zn-loaded aminated halloysite nanotubes. Step 2: Mix phytic acid aqueous solution, phosphoric acid aqueous solution, urea, melamine, formaldehyde solution and water, and react at pH 2-3 and temperature 75-80℃ for 1-2 hours to obtain a nitrogen-phosphorus prepolymer. Mix the obtained nitrogen-phosphorus prepolymer with a dispersion of Zn-loaded aminated halloysite nanotubes, and continue to react at 95-100℃ for 3-5 hours. Mix the reaction product with 10 times its volume of acetone, collect the precipitate, and obtain a flame retardant synergist by washing, drying and pulverizing the precipitate.

[0007] Preferably, the flame retardant is aluminum diethylphosphonate.

[0008] Preferably, the vulcanizing agent is at least one selected from dicumyl peroxide, benzoyl peroxide, di(2,4)-dimethylbenzene vulcanizing agent, and di(2,5)-dimethylbenzene vulcanizing agent.

[0009] Preferably, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0010] Preferably, the release agent is zinc stearate.

[0011] Preferably, the preparation method of the aminated halloysite nanotubes includes the following steps: Halloysite nanotubes were dispersed in anhydrous ethanol and then reacted with a silane coupling agent hydrolysate to obtain aminated halloysite nanotubes.

[0012] Preferably, in the preparation method of the flame retardant synergist, the water-soluble zinc salt is zinc nitrate hexahydrate.

[0013] More preferably, the mass ratio of zinc nitrate hexahydrate, aminated halloysite nanotubes, and water is 3:10:50.

[0014] Preferably, in step 2, the concentration of the phytic acid aqueous solution is 50 wt% and the concentration of the phosphoric acid aqueous solution is 85 wt%. The nitrogen- and phosphorus-containing prepolymer is obtained by mixing and reacting phytic acid aqueous solution, phosphoric acid aqueous solution, urea, melamine, formaldehyde solution and water in a mass ratio of 3:1:3:1.2:5:10. The Zn-loaded aminated halloysite nanotube dispersion was obtained by ultrasonic dispersion of Zn-loaded aminated halloysite nanotubes and water at a mass ratio of 1:1. The nitrogen- and phosphorus-containing prepolymer and the Zn-loaded aminated halloysite nanotube dispersion are mixed and reacted at a mass ratio of 1:1.

[0015] In a second aspect, the present invention provides a method for preparing the high flame-retardant and highly flexible composite material for cables described in the first aspect, the preparation method comprising the following steps: Step 1: Place the flame retardant synergist and polyether modified silicone oil in a high-speed mixer and mix for 15 minutes at 500-1000 r / min and 60℃ to obtain mixture A; Step 2: Add methyl vinyl silicone rubber, mixture A, hydrogenated styrene-butadiene block copolymer, antioxidant, and release agent to a mixer and mix at room temperature for 8 minutes. Add flame retardant and continue mixing for 5 minutes. Transfer the resulting rubber compound to a two-roll mill, add vulcanizing agent, pass through a thin mill 6 times, form a triangular package 4 times, and sheet it. Step 3: Extrude the compounded rubber through an extruder and vulcanize it in a 200°C hot air vulcanization tunnel for 10-20 minutes to obtain the composite material.

[0016] The beneficial effects of this invention are: 1. This invention utilizes the synergistic effect of a phosphorus-containing flame retardant (preferably aluminum diethylphosphonate) and a phosphorus-nitrogen-zinc-halolite composite flame retardant synergist to achieve a vertical burning rating of UL94 V-0, an oxygen index ≥36.8%, and a maximum smoke density ≤234, effectively suppressing fire spread and smoke release, and ensuring safe use in extreme scenarios. 2. The hydrogenated styrene-butadiene block copolymer and methyl vinyl silicone rubber in this invention synergistically enhance the flexibility of the matrix. Combined with the plasticizing effect of polyether modified silicone oil, the material has a Shore A hardness of only 40-45 and an elongation at break of 276%-296%. It also has good bending and torsional resistance, making it suitable for complex and narrow wiring and dynamic laying environments. At the same time, the tensile strength is maintained at 12.1-14.2 MPa, which meets the mechanical strength requirements for cable use. Detailed Implementation

[0017] Those skilled in the art can refer to the content of this document to appropriately improve the process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention.

[0018] The products and methods of the present invention have been described through preferred embodiments. Those skilled in the art will be able to make modifications or appropriate alterations and combinations to the products and methods described herein without departing from the content, spirit and scope of the present invention, so as to realize and apply the technology of the present invention.

[0019] Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. Materials, reagents, etc., used are commercially available unless otherwise specified. Unless otherwise stated, substances described in this invention are calculated as percentages and parts by mass.

[0020] I. Raw Materials Halloysite nanotubes: purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; Silane coupling agent KH-550: purchased from Nanjing Pinning Coupling Agent Co., Ltd.; Hydrogenated styrene-butadiene block copolymer: purchased from Dongguan Longsheng Engineering Plastics Co., Ltd.; Polyether-modified silicone oil: purchased from Hubei Chushengwei Chemical Co., Ltd.; Aluminum diethylphosphinate: purchased from Suzhou Lianxiong Fine Chemical Technology Co., Ltd.; All raw materials used in the other embodiments or comparative examples are commercially available.

[0021] II. Aminated halloysite nanotubes The preparation method of the aminated halloysite nanotubes is as follows: Step 1: Mix halloysite nanotubes and anhydrous ethanol in a reaction vessel at a mass-to-volume ratio of 1:10 g / mL. In a 60°C water bath, mechanically stir at 800 rpm and ultrasonically disperse for 30 min to form a uniform suspension. Step 2: Premix KH-550 and distilled water at a mass ratio of 1:1 and stir for 5 minutes to allow for initial hydrolysis, obtaining a hydrolysate. Add the hydrolysate dropwise to the suspension, controlling the dropping rate at 1-2 mL / min, with an addition amount of 6 wt% of the suspension. After the addition is complete, raise the temperature to 80℃ and reflux the reaction for 8 hours under nitrogen protection. After the reaction is complete, centrifuge to collect the solid product and wash it three times with anhydrous ethanol. Step 3: Place the solid product in an 80℃ vacuum drying oven and dry for 10-12 hours to obtain aminated halloysite nanotubes, which are then sealed and stored for later use.

[0022] III. Flame Retardant Synergists The specific preparation method of the flame retardant synergist is as follows (the following parts are by weight): Step 1: Dissolve 30 parts of zinc nitrate hexahydrate in 500 parts of deionized water, stirring until completely dissolved to form a clear solution. Add 100 parts of aminated halloysite nanotubes to the solution and stir at 500 rpm for 6 hours in a 50°C water bath. During this process, Zn... 2+The aminated halloysite nanotubes were loaded onto the surface and inside the tubes through ion exchange and coordination. After the reaction was completed, the mixture was filtered and washed with deionized water until the conductivity of the filtrate remained basically unchanged. The filter cake obtained by filtration was placed in a vacuum drying oven at 100°C and dried to constant weight. After grinding, the aminated halloysite nanotubes loaded with Zn were obtained. Step 2: In another reactor, add 30 parts of 50% phytic acid aqueous solution, 10 parts of 85% phosphoric acid aqueous solution, 30 parts of urea, 12 parts of melamine, 50 parts of formaldehyde solution and 100 parts of deionized water, adjust the pH to 2.0 with concentrated hydrochloric acid, raise the temperature to 75-80℃, and prepolymerize for 2 hours to obtain a viscous nitrogen-phosphorus prepolymer. Step 3: Disperse 100 parts of Zn-loaded aminated halloysite nanotubes in 100 parts of deionized water and sonicate for 20 min. Then, slowly add this dispersion to the prepolymer in Step 2, keep the temperature at 80℃, and raise the temperature of the reaction system to 95-100℃ under continuous stirring to carry out the polycondensation reaction. During the reaction, the prepolymer further polymerizes on the surface of the Zn-loaded aminated halloysite nanotubes to form a strong coating layer. This stage of the reaction lasts for 5 h. After the reaction is completed, slowly adjust the pH of the system to 5.0 with dilute ammonia solution and continue to mature for 1 h to make the shell structure more stable. Step 4: Pour the viscous reaction product obtained in Step 3 into 10 times its volume of acetone to precipitate the product. After standing, discard the supernatant and filter the precipitate. Wash the filter cake with acetone and deionized water three times each, alternating between the two. Place the washed filter cake in a forced-air drying oven at 100-110℃ for initial drying for 4 hours, and then transfer it to a vacuum drying oven at 80℃ for deep drying for 24 hours. Crush the dried lumps with an ultrafine pulverizer and pass them through a 300-mesh sieve to obtain a light yellow fine powder, which is the flame retardant synergist.

[0023] IV. Highly flame-retardant and highly flexible composite materials 1. Example 1 The specific method for preparing the composite material is as follows: Step 1: Place the flame retardant synergist and polyether modified silicone oil in a high-speed mixer and mix for 15 minutes at 500-1000 r / min and 60℃ to obtain mixture A; Step 2: Add methyl vinyl silicone rubber, mixture A, hydrogenated styrene-butadiene block copolymer, antioxidant, and release agent to a mixer and mix at room temperature for 8 minutes. Add flame retardant and continue mixing for 5 minutes. Transfer the resulting rubber compound to a two-roll mill, add vulcanizing agent, pass through a thin mill 6 times, form a triangular package 4 times, and sheet it. Step 3: Extrude the compounded rubber into cable sheath tubes using an extruder, and vulcanize them in a 200°C hot air vulcanization oven for 10 minutes to obtain the sample of Example 1; The raw materials used in the above preparation method are in the following proportions by weight: 100 parts of methyl vinyl silicone rubber, 25 parts of hydrogenated styrene-butadiene block copolymer, 5 parts of polyether modified silicone oil, 50 parts of aluminum diethylphosphinate flame retardant, 10 parts of flame retardant synergist, 2 parts of benzoyl peroxide vulcanizing agent, 2 parts of zinc stearate release agent, and 1 part of antioxidant 1010.

[0024] 2. Example 2 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 130 parts of methyl vinyl silicone rubber, 27 parts of hydrogenated styrene-butadiene block copolymer, 8 parts of polyether modified silicone oil, 60 parts of aluminum diethylphosphinate flame retardant, 13 parts of flame retardant synergist, 2 parts of bis(2,4)-dichloroethylene vulcanizing agent, 3 parts of zinc stearate release agent, and 2 parts of antioxidant 168, to obtain the sample of Example 2.

[0025] 3. Example 3 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 150 parts of methyl vinyl silicone rubber, 30 parts of hydrogenated styrene-butadiene block copolymer, 10 parts of polyether modified silicone oil, 70 parts of aluminum diethylphosphinate flame retardant, 15 parts of flame retardant synergist, 5 parts of bis(2,5)-pentyl chloride vulcanizing agent, 3 parts of zinc stearate release agent, and 5 parts of antioxidant 1010, to obtain the sample of Example 3.

[0026] 4. Comparative Example 1 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 125 parts of methyl vinyl silicone rubber, 5 parts of polyether modified silicone oil, 50 parts of aluminum diethylphosphinate flame retardant, 10 parts of flame retardant synergist, 2 parts of benzoyl peroxide vulcanizing agent, 2 parts of zinc stearate release agent, and 1 part of antioxidant 1010. The difference from Example 1 was that hydrogenated styrene-butadiene block copolymer was not added, and the missing amount was made up with methyl vinyl silicone rubber. The rest remained unchanged, and the sample of Comparative Example 1 was obtained.

[0027] 5. Comparative Example 2 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 100 parts of methyl vinyl silicone rubber, 25 parts of hydrogenated styrene-butadiene block copolymer, 5 parts of polyether modified silicone oil, 70 parts of aluminum diethylphosphonate flame retardant, 2 parts of benzoyl peroxide vulcanizing agent, 2 parts of zinc stearate release agent, and 1 part of antioxidant 1010. The difference from Example 1 is that no flame retardant synergist was added, and the amount of aluminum diethylphosphonate flame retardant was increased to 70 parts, while the rest remained unchanged, to obtain the sample of Comparative Example 2.

[0028] 6. Comparative Example 3 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 100 parts of methyl vinyl silicone rubber, 25 parts of hydrogenated styrene-butadiene block copolymer, 5 parts of polyether modified silicone oil, 50 parts of aluminum diethylphosphinate flame retardant, 7 parts of aminated halloysite nanotubes, 3 parts of zinc nitrate, 2 parts of benzoyl peroxide vulcanizing agent, 2 parts of zinc stearate release agent, and 10101 parts of antioxidant. The difference from Example 1 is that the flame retardant synergist was replaced with 8 parts of aminated halloysite nanotubes and 2 parts of zinc nitrate. Step 1 was adjusted to premix 8 parts of aminated halloysite nanotubes and 2 parts of zinc nitrate with polyether modified silicone oil. The remaining steps remained unchanged, and the sample of Comparative Example 3 was obtained.

[0029] 7. Comparative Example 4 Referring to the preparation method of Example 1, the raw materials were prepared in the following proportions by mass: 100 parts of methyl vinyl silicone rubber, 25 parts of hydrogenated styrene-butadiene block copolymer, 5 parts of polyether modified silicone oil, 20 parts of brucite, 30 parts of magnesium hydroxide, 10 parts of flame retardant synergist, 2 parts of benzoyl peroxide vulcanizing agent, 2 parts of zinc stearate release agent, and 1 part of antioxidant 1010. The difference from Example 1 was that the aluminum diethylphosphines flame retardant was replaced with 20 parts of brucite and 30 parts of magnesium hydroxide, while the rest remained unchanged, resulting in the sample of Comparative Example 4.

[0030] V. Performance Testing Table 1 Test Items and Corresponding Test Methods Test item Test standard Vertical burning grade UL94 Oxygen index (LOI) GB / T 2406.2-2009 Material hardness ASTM D 2240-2015 Elongation at break GB / T 1040.3-2006 Tensile strength GB / T 1040.3-2006 Smoke density (maximum) GB / T 8323.2-2008 Table 2 Performance test results of samples from Examples 1-3 and Comparative Examples 1-4 Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Vertical burning grade V-0 V-0 V-0 V-0 V-1 V-1 V-1 Oxygen index (LOI) % 37.2 39.3 36.8 36.7 32.1 33.8 31.5 Material hardness / Shore A 43 40 45 58 42 43 49 Elongation at break % 283 296 276 212 255 291 195 Tensile strength / MPa 12.8 14.2 12.1 15.5 13.8 11.2 16.3 Smoke density 224 213 234 221 345 328 287 Results analysis: As shown in Table 2, the composite materials prepared in Examples 1-3 all exhibit excellent comprehensive performance: the vertical burning rating all reach UL94 V-0, the oxygen index (LOI) is maintained at 36.8%-39.3%, achieving a high flame retardant standard; the Shore A hardness is only 40-45, and the elongation at break is 276%-296%, demonstrating good flexibility and tensile deformation resistance; the smoke density is controlled at 213-234, with a significant smoke suppression effect.

[0031] Comparative Example 1, without the addition of hydrogenated styrene-butadiene block copolymer, was supplemented with methyl vinyl silicone rubber, resulting in a surge in its Shore A hardness to 58 and a decrease in elongation at break to 212%. Its flexibility and resistance to deformation were significantly deteriorated, while the flame retardant properties of the two were relatively similar. This indicates that the hydrogenated styrene-butadiene block copolymer can effectively improve the flexibility of silicone rubber and is one of the core components ensuring the high flexibility of the material.

[0032] Compared to Example 1, Comparative Example 2 did not add a flame retardant synergist, but the amount of flame retardant increased to 70 parts, resulting in a drop in its vertical burning rating to V-1, an oxygen index of only 32.1%, and a soaring smoke density of 345, with both flame retardant and smoke suppression performance significantly declining. Compared to Example 1, Comparative Example 3 used aminated halloysite nanotubes and zinc nitrate to replace the flame retardant synergist, and Comparative Example 3 also only reached a V-1 rating, with an oxygen index of 33.8% and a smoke density of 328, showing a significant performance difference. This is because, in the initial combustion stage, the phosphorus and nitrogen components in the aluminum diethylphosphonate and the flame retardant synergist shell in Example 1 decompose simultaneously. The aluminum diethylphosphonate releases phosphorus-oxygen free radicals, interrupting the combustion chain reaction, while the non-combustible gases such as ammonia released by the flame retardant synergist further dilute the oxygen in the combustion zone, with a dual effect inhibiting the spread of combustion in the early stages. In the intense heating stage, the flame retardant synergist decomposes to produce a large amount of highly dehydrating polyphosphoric acid, which reacts with the loaded Zn. 2+ The synergistic effect of metal ions strongly catalyzes the dehydration of polymer systems and their own carbon sources into char. At the same time, the decomposition products of aluminum diethylphosphonate also participate in the catalytic char formation process, accelerating the formation of the char layer. In the char layer strengthening stage, halloysite nanotubes, the core of the flame retardant synergist, serve as an inorganic framework. Together with the formed carbon, phosphorus, nitrogen residues and metal oxides such as ZnO, they construct a three-dimensional reinforced ceramic expanded char layer. This char layer is more continuous, stronger, and has better heat insulation than the char layer formed by using aluminum diethylphosphonate alone. It can effectively block the transfer of heat and oxygen, achieving highly efficient flame retardancy.

[0033] Compared to Example 1, Comparative Example 4 replaced aluminum diethylphosphonate with brucite and magnesium hydroxide, resulting in a vertical burning rating of only V-1, an oxygen index of 31.5%, and an elongation at break of 195%. The flame retardant properties and flexibility were significantly deteriorated. This indicates that the hydroxide flame retardant has low flame retardant efficiency and cannot achieve a synergistic flame retardant effect with the flame retardant synergist provided by this invention. A higher filling amount is required to achieve a basic flame retardant effect, which leads to damage to the material's flexibility and limited performance.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly flame-retardant and highly flexible composite material for cables, characterized in that, The composite material contains the following components in parts by weight: 100-150 parts of methyl vinyl silicone rubber, 25-30 parts of hydrogenated styrene-butadiene block copolymer, 5-10 parts of polyether modified silicone oil, 50-70 parts of flame retardant, 10-15 parts of flame retardant synergist, 2-5 parts of vulcanizing agent, 2-3 parts of release agent, and 1-5 parts of antioxidant. The flame retardant is a phosphorus-containing flame retardant; The flame retardant synergist is prepared by the following method: Step 1: Dissolve water-soluble zinc salt in water to obtain a zinc ion-containing solution, then mix the solution with aminated halloysite nanotubes, stir at 50-70℃ for 6-10 hours, filter and collect the solid, and dry the solid to obtain Zn-loaded aminated halloysite nanotubes. Step 2: Mix phytic acid aqueous solution, phosphoric acid aqueous solution, urea, melamine, formaldehyde solution and water, and react at pH 2-3 and temperature 75-80℃ for 1-2 hours to obtain a nitrogen-phosphorus prepolymer. Mix the obtained nitrogen-phosphorus prepolymer with a dispersion of Zn-loaded aminated halloysite nanotubes, and continue to react at 95-100℃ for 3-5 hours. Mix the reaction product with 10 times its volume of acetone, collect the precipitate, and obtain a flame retardant synergist by washing, drying and pulverizing the precipitate.

2. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The flame retardant is aluminum diethylphosphinate.

3. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The vulcanizing agent is at least one of dicumyl peroxide, benzoyl peroxide, di(2,4)-di(2,4)-di(2,5 ...

4. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010 and antioxidant 168.

5. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The release agent is zinc stearate.

6. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The preparation method of the aminated halloysite nanotubes includes the following steps: Halloysite nanotubes were dispersed in anhydrous ethanol and then reacted with a silane coupling agent hydrolysate to obtain aminated halloysite nanotubes.

7. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, In the preparation method of the flame retardant synergist, the water-soluble zinc salt is zinc nitrate hexahydrate.

8. The high flame-retardant and highly flexible composite material for cables according to claim 7, characterized in that, The mass ratio of zinc nitrate hexahydrate, aminated halloysite nanotubes, and water is 3:10:

50.

9. The high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, In step 2, the concentration of the phytic acid aqueous solution is 50 wt%, and the concentration of the phosphoric acid aqueous solution is 85 wt%. The nitrogen- and phosphorus-containing prepolymer is obtained by mixing and reacting phytic acid aqueous solution, phosphoric acid aqueous solution, urea, melamine, formaldehyde solution and water in a mass ratio of 3:1:3:1.2:5:

10. The Zn-loaded aminated halloysite nanotube dispersion was obtained by ultrasonic dispersion of Zn-loaded aminated halloysite nanotubes and water at a mass ratio of 1:

1. The nitrogen- and phosphorus-containing prepolymer and the Zn-loaded aminated halloysite nanotube dispersion are mixed and reacted at a mass ratio of 1:

1.

10. The method for preparing the high flame-retardant and highly flexible composite material for cables according to claim 1, characterized in that, The preparation method includes the following steps: Step 1: Place the flame retardant synergist and polyether-modified silicone oil in a high-speed mixer and mix for 15 minutes at 500-1000 r / min and 60℃ to obtain mixture A; Step 2: Add methyl vinyl silicone rubber, mixture A, hydrogenated styrene-butadiene block copolymer, antioxidant, and release agent to a mixer and mix at room temperature for 8 minutes. Add flame retardant and continue mixing for 5 minutes. Transfer the resulting rubber compound to a two-roll mill, add vulcanizing agent, pass through a thin mill 6 times, form a triangular package 4 times, and sheet it. Step 3: Extrude the compounded rubber through an extruder and vulcanize it in a 200°C hot air vulcanization tunnel for 10-20 minutes to obtain the composite material.