A flexible and bend-resistant cable

Abstract

The present invention provides a flexible bend-resistant cable, including an outer sheath, and the outer sheath comprises raw materials in the following parts by weight: 65-75 parts of linear low-density polyethylene resin, 10-20 parts of metallocene linear low-density polyethylene, 15-25 parts of ethylene-vinyl acetate copolymer, 3.5-5 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.4-0.65 parts of wrinkled graphene / nanocarbon sphere composite material, 4.5-6.5 parts of inorganic filler, 4.5-6 parts of flame retardant, 0.1-0.3 parts of silane coupling agent, 1.2-1.8 parts of lubricant, and 0.2-0.5 parts of antioxidant. The cable outer sheath of the present invention has high strength, high flexibility and bend resistance on the basis.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and particularly to a flexible and bend-resistant cable. Background Art

[0002] As an important part of the power system, cables are used to ensure the stability and reliability of power supply. With the continuous development of power energy technology, cables have penetrated into all aspects of national economic life. At present, when some cables are applied to equipment that needs to move or vibrate frequently, they often need to withstand pulling, bending or twisting. Therefore, the cables need to have flexibility and bend resistance to better ensure the stability and flexibility during the use of the equipment.

[0003] To improve the bend resistance of cables, generally, the outer sheath material can be optimized. At present, a large amount of inorganic fillers are used in the outer sheath material to ensure its strength and wear resistance. However, when there are too many inorganic fillers, it is very likely that the softness and bend resistance of the outer sheath will be reduced. If there are not enough inorganic fillers, it is easy to cause insufficient strength of the outer sheath. Therefore, more efficient reinforcing materials need to be added to the outer sheath material so that it can improve the strength of the outer sheath while having excellent softness and bend resistance with a small amount of inorganic fillers. Summary of the Invention

[0004] The purpose of the present invention is to provide a flexible and bend-resistant cable. On the basis of high strength, the outer sheath of the cable also has high softness and bend resistance.

[0005] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] A flexible and bend-resistant cable includes an outer sheath. The outer sheath comprises the following raw materials in parts by weight: 65 - 75 parts of linear low-density polyethylene resin, 10 - 20 parts of metallocene linear low-density polyethylene, 15 - 25 parts of ethylene-vinyl acetate copolymer, 3.5 - 5 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.4 - 0.65 parts of wrinkled graphene / nanocarbon sphere composite material, 4.5 - 6.5 parts of inorganic filler, 4.5 - 6 parts of flame retardant, 0.1 - 0.3 parts of silane coupling agent, 1.2 - 1.8 parts of lubricant, and 0.2 - 0.5 parts of antioxidant;

[0007] The preparation method of the wrinkled graphene / nanocarbon sphere composite material comprises the following steps:

[0008] S1: Add multi-layer graphene oxide and nano-silica into water. After stirring and mixing, obtain a graphene oxide / nano-silica dispersion; then atomize the graphene oxide / nano-silica dispersion, and use argon as the carrier gas for the gas obtained after atomization treatment, and introduce it into a heating chamber at 850 - 900 °C for heat treatment, and then collect the obtained composite; place the composite in a hydrofluoric acid solution to etch away the nano-silica, and after centrifugation, washing with water, and vacuum drying, obtain the wrinkled graphene;

[0009] S2: Place the wrinkled graphene in an aqueous glucose solution for hydrothermal reaction; after cooling to room temperature, carry out centrifugation, washing, and vacuum drying to obtain a wrinkled graphene / nano-carbon sphere composite material.

[0010] When the method of the present invention prepares wrinkled graphene, using multi-layer graphene oxide as the main raw material and cooperating with an appropriate amount of nano-silica as a template agent, by spraying the graphene oxide / nano-silica dispersion and performing heat treatment at 850 - 900 °C, at this time, based on the capillary force generated during liquid evaporation, wrinkles can be formed on the surface of graphene. At the same time, the added template agent nano-silica can also be adsorbed on graphene and wrapped by graphene during this process, further promoting the formation of a wrinkled structure of graphene. After that, by etching away the nano-silica with a hydrofluoric acid solution, wrinkled graphene with a rich wrinkled structure can be prepared.

[0011] After that, further place this wrinkled graphene in an aqueous glucose solution for hydrothermal reaction. Through the action of hydrothermal reaction, glucose is gradually converted into nano-carbon spheres and loaded on the surface of the wrinkled graphene, forming fixed anchor points on the surface of the wrinkled graphene.

[0012] The present invention constructs a wrinkled structure for graphene and constructs rough anchor points on the surface of the wrinkled graphene with nano-carbon spheres, both of which will improve the tensile strength, elongation at break, and flexural strength of the obtained outer sheath material.

[0013] Preferably, in step S1), the particle size of the multi-layer graphene oxide is 1 - 10 μm, and the particle size of the nano-silica is 10 - 30 nm;

[0014] In the graphene oxide / nano-silica dispersion, the concentration of the multi-layer graphene oxide is 3 - 6 mg / mL; the concentration of the nano-silica is 1.5 - 3 mg / mL.

[0015] Preferably, in step S2, the concentration of the aqueous glucose solution is 0.2 - 0.5 mol / L; the temperature of the hydrothermal reaction is 170 - 190 °C, and the time of the hydrothermal reaction is 5 - 7 h.

[0016] Preferably, the inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.2 - 0.5, or the inorganic filler is composed of montmorillonite and calcium carbonate in a mass ratio of 1:0.2 - 0.5.

[0017] Preferably, the inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.2 - 0.5; the preparation method of the modified montmorillonite includes the following steps:

[0018] A. Place montmorillonite in an ammonium chloride aqueous solution for ultrasonic mixing. After standing and precipitating, vacuum-dry the obtained precipitate, and then perform calcination treatment in an air atmosphere; then pulverize and sieve to obtain pretreated montmorillonite;

[0019] B. Place the pretreated montmorillonite in a reaction chamber. First, introduce water vapor for 8 - 10 s. Then introduce argon to remove the water vapor in the reaction chamber. Next, introduce a mixed gas of argon and titanium tetrachloride gas for 10 - 13 s. Then introduce argon to remove the titanium tetrachloride gas in the reaction chamber;

[0020] C. Repeat step B 25 - 40 times; and continue to introduce argon to purge the obtained montmorillonite for 20 - 30 min to obtain the modified montmorillonite.

[0021] When preparing the modified montmorillonite in the present invention, first place montmorillonite in an ammonium chloride aqueous solution for mixing, and then perform drying and calcination treatment. During the calcination process, ammonium chloride decomposes into gas. Through this operation, the pores inside montmorillonite can be increased to obtain porous montmorillonite. Then, by alternately introducing water vapor and titanium tetrachloride gas into the porous montmorillonite, an appropriate amount of nano-titanium dioxide can be deposited more uniformly on the surface and inside the pores of the porous montmorillonite.

[0022] By increasing the pores of montmorillonite in the present invention, it is beneficial for water vapor and titanium tetrachloride gas to disperse inside montmorillonite subsequently, which is more conducive to the loading of nano-titanium dioxide inside the pores of montmorillonite, and improves the performance of the obtained modified montmorillonite. The dispersibility of the modified montmorillonite obtained by the above method in the polyethylene resin matrix is significantly enhanced, and the outer sheath can have higher strength, wear resistance, etc. without affecting the flexibility of the outer sheath.

[0023] Moreover, by dispersing and loading an appropriate amount of nano-titanium dioxide in porous montmorillonite, the obtained modified montmorillonite exhibits excellent flame retardancy. The highly dispersed nano-titanium dioxide cooperates with the lamellar montmorillonite to form a physical barrier layer in the polyethylene resin matrix, slowing down the transfer of heat and oxygen during combustion. And nano-titanium dioxide can cooperate with DOPO-based flame retardants to capture free radicals in the combustion reaction, thereby interrupting the combustion chain reaction and reducing the combustion rate. At the same time, DOPO-based flame retardants can decompose to produce phosphate esters to react with combustible substances to form a carbide layer for flame retardancy, and nano-titanium dioxide can further promote the formation of the carbon layer and strengthen the flame retardant effect. Combining this modified montmorillonite with the flame retardants (DOPO or DOPO derivatives) used in the present invention can make the overall outer sheath exhibit excellent flame retardancy. In addition, in the wrinkled graphene / nano-carbon sphere composite material of the present invention, the wrinkled graphene can also form a certain physical isolation layer and can block the diffusion of oxygen and heat to the inside of the material, thereby improving the flame retardancy of the outer sheath.

[0024] In addition, by adding modified montmorillonite in the present invention, nano-titanium dioxide can be highly dispersed in the outer sheath. When combined with the wrinkled graphene / nano-carbon sphere composite material, the outer sheath has high antibacterial properties; and the presence of nano-titanium dioxide can reduce the influence of ultraviolet irradiation on the outer sheath and slow down the aging and degradation caused by ultraviolet irradiation.

[0025] Preferably, the mass fraction of the ammonium chloride aqueous solution is 30-40%; during the calcination treatment, the temperature is raised to 700-750°C at a rate of 3-6°C / min and calcined for 2-3 h;

[0026] In step B, the gas flow rate of water vapor is 500-1000 sccm; the gas flow rate of argon is 1500-2000 sccm, and the gas flow rate of titanium tetrachloride gas is 500-1000 sccm.

[0027] Preferably, the flame retardant is DOPO or a DOPO derivative.

[0028] Preferably, the flexible bend-resistant cable includes a cable core, and the cable core is composed of a copper conductor and a cross-linked polyethylene inner sheath; an aluminum-plastic composite tape and a mica wrapping tape are sequentially coated outside the cable core, and the outer sheath is coated outside the mica wrapping tape.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] The present invention uses linear low-density polyethylene as the main resin, which has high flexibility, appropriate strength, etc., and a low cost. Further, by combining linear low-density polyethylene resin with metallocene linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylate-maleic anhydride terpolymer, a resin matrix with a higher softness can be obtained. At the same time, it also has a relatively high basic strength, effectively enhancing the bonding performance between the polyethylene resin matrix and other inorganic materials, and achieving a balance between cost and performance.

[0031] The wrinkled graphene / nanocarbon sphere composite prepared by the present invention is based on the rich wrinkled structure of wrinkled graphene and the firmly loaded nanocarbon spheres thereon. This not only endows graphene with high dispersibility, but more importantly, it can be more firmly embedded in the polyethylene resin matrix through this wrinkled structure and the nanocarbon sphere anchor points. When subjected to external forces, it is less likely to peel off from the polyethylene resin matrix, enabling the wrinkled graphene to efficiently exert its reinforcing performance. And because the wrinkled graphene has a wrinkled structure, it can better adapt to deformation when subjected to external forces, thereby making the sheath material have a higher bending strength, etc.

[0032] The present invention uses a small amount of wrinkled graphene / nanocarbon sphere composite as an efficient reinforcing material, in combination with a small amount of inorganic fillers, to enable the tensile strength of the outer sheath material to reach above 20.5 MPa, the elongation at break to be above 450%, and the bending strength to reach above 14.5 MPa. That is, on the basis of using low-cost linear low-density polyethylene resin as the main body, the present invention prepares a high-strength, highly bend-resistant, and flexible outer sheath material.

[0033] In addition, by preferably using the modified montmorillonite prepared by the method of the present invention as the main inorganic filler, the obtained outer sheath material can further enhance its strength, etc. while maintaining excellent flexibility. At the same time, the modified montmorillonite is combined with the flame retardant used in the present invention, etc., enabling the outer sheath to overall exhibit excellent flame retardant performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a schematic structural diagram of the flexible and bend-resistant cable of the present invention;

[0036] In the figure: 1. Copper conductor; 2. Crosslinked polyethylene inner sheath; 3. Aluminum-plastic composite tape; 4. Mica wrapping tape; 5. Outer sheath. Detailed implementation mode

[0037] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Linear low density polyethylene resin: LL4004EL, Exxon;

[0039] Metallocene linear low density polyethylene: 5220G, DowDuPont;

[0040] Ethylene-vinyl acetate copolymer: 2315, Hanwha Korea;

[0041] Ethylene-acrylate-maleic anhydride terpolymer: 3410, Arkema France;

[0042] Multi-layer graphene oxide: Hangzhou Zheming New Materials Co., Ltd.;

[0043] Nano-silica: Hubei Xinyuhong Biomedical Technology Co., Ltd.;

[0044] Montmorillonite: Hebei Hengyue Mineral Products Co., Ltd.;

[0045] Calcium carbonate: CC-2000, Jiangxi Guangyuan Chemical Industry;

[0046] DOPO: Guangzhou Shanghe Chemical Technology Co., Ltd.;

[0047] PE wax: JRF-200, Shanghai Jinhu Rili Plastics Co., Ltd.;

[0048] Antioxidant 1010: Beijing Jiyi New Materials.

[0049] Example 1

[0050] A flexible and bend-resistant cable, as Figure 1 shown, includes a cable core, which is composed of a copper conductor 1 and a cross-linked polyethylene inner sheath 2; an aluminum-plastic composite tape 3 and a mica wrapping tape 4 are successively coated outside the cable core, and an outer sheath 5 is coated outside the mica wrapping tape 4.

[0051] The outer sheath 5 comprises raw materials in the following parts by weight: 70 parts of linear low density polyethylene resin, 15 parts of metallocene linear low density polyethylene, 15 parts of ethylene-vinyl acetate copolymer, 4 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.5 part of wrinkled graphene / nano carbon sphere composite material, 5 parts of inorganic filler, 5 parts of DOPO, 0.3 part of silane coupling agent KH550, 1.7 parts of PE wax, and 0.2 part of antioxidant 1010. The inorganic filler consists of montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0052] In this embodiment, the wrinkled graphene / nano carbon sphere composite material comprises wrinkled graphene and nano carbon spheres loaded on the wrinkled graphene. The preparation method of the wrinkled graphene / nano carbon sphere composite material comprises the following steps:

[0053] S1: Prepare wrinkled graphene:

[0054] S11: Add multi-layer graphene oxide and nano silicon dioxide into water, and after stirring and mixing, obtain a graphene oxide / nano silicon dioxide dispersion; wherein, the particle size of the multi-layer graphene oxide is 4-7 μm, and the particle size of the nano silicon dioxide is 10-30 nm; in the graphene oxide / nano silicon dioxide dispersion, the concentration of the multi-layer graphene oxide is 5 mg / mL, and the concentration of the nano silicon dioxide is 2 mg / mL;

[0055] S12: Then atomize the graphene oxide / nano silicon dioxide dispersion, and use argon as the carrier gas for the gas obtained after the atomization treatment, bring it into a heating chamber at 900 °C for heat treatment, and then collect the obtained composite;

[0056] S13: Place the composite in a hydrofluoric acid solution with a mass fraction of 30%, etch off the nano silicon dioxide, and after centrifugation, washing, and vacuum drying, obtain the wrinkled graphene.

[0057] S2: Place 30 g of wrinkled graphene in 5 L of a glucose aqueous solution with a concentration of 0.3 mol / L for hydrothermal reaction. The temperature of the hydrothermal reaction is 190 °C, and the time of the hydrothermal reaction is 6 h; after cooling to room temperature, perform centrifugation, washing, and vacuum drying to obtain the wrinkled graphene / nano carbon sphere composite material.

[0058] The preparation method of the granule for the outer sheath 5 is as follows:

[0059] The outer sheath 5 is first placed in a high-speed mixer and mixed with the wrinkled graphene / nanocarbon sphere composite material, inorganic filler, and silane coupling agent KH550 in the raw materials for 20 min, then the remaining raw materials of the outer sheath 5 are added, and the mixture is mixed at 70 °C for 12 min. Then it is transferred to a twin-screw extruder. The screw speed is 200 rpm, the temperature of the first zone is 150 °C, the temperature of the second zone is 165 °C, the temperature of the third zone is 175 °C, the temperature of the fourth zone is 180 °C, and the die head temperature is 180 °C. The extruded strip is cooled by a water cooling tank and then pelletized to obtain the pellets for the outer sheath.

[0060] Example 2

[0061] A flexible bend-resistant cable includes a cable core, which is composed of a copper conductor 1 and a cross-linked polyethylene inner sheath 2; an aluminum-plastic composite tape 3 and a mica wrapping tape 4 are sequentially coated on the outer side of the cable core, and an outer sheath 5 is coated on the outer side of the mica wrapping tape 4.

[0062] The outer sheath 5 includes the following raw materials in parts by weight: 65 parts of linear low-density polyethylene resin, 20 parts of metallocene linear low-density polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 5 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.65 part of wrinkled graphene / nanocarbon sphere composite material, 6.5 parts of inorganic filler, 5 parts of DOPO, 0.1 part of silane coupling agent KH550, 1.2 parts of PE wax, and 0.2 part of antioxidant 1010. The inorganic filler is composed of montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0063] In this example, the wrinkled graphene / nanocarbon sphere composite material includes wrinkled graphene and nanocarbon spheres loaded on the wrinkled graphene. The preparation method of the wrinkled graphene / nanocarbon sphere composite material includes the following steps:

[0064] S1: Prepare wrinkled graphene:

[0065] S11: Add multi-layer graphene oxide and nano-silica to water, stir and mix to obtain a graphene oxide / nano-silica dispersion; among them, the particle size of the multi-layer graphene oxide is 4-7 μm, and the particle size of the nano-silica is 10-30 nm; in the graphene oxide / nano-silica dispersion, the concentration of the multi-layer graphene oxide is 4 mg / mL, and the concentration of the nano-silica is 2 mg / mL;

[0066] S12: Then atomize the graphene oxide / nano-silica dispersion, use argon as the carrier gas for the gas obtained after atomization treatment, bring it into a heating chamber at 880 °C for heat treatment, and then collect the obtained composite;

[0067] S13: Place the composite in a hydrofluoric acid solution with a mass fraction of 30% to etch away the nano-silica. After centrifugation, washing with water, and vacuum drying, the wrinkled graphene is obtained.

[0068] S2: Place 30 g of wrinkled graphene in 5 L of an aqueous glucose solution with a concentration of 0.4 mol / L for hydrothermal reaction. The temperature of the hydrothermal reaction is 175 °C, and the time of the hydrothermal reaction is 5.5 h. After cooling to room temperature, centrifugation, washing, and vacuum drying are carried out to obtain a wrinkled graphene / nano-carbon sphere composite material.

[0069] The preparation method of the pellet for the outer sheath 5 is the same as that in Example 1.

[0070] Example 3

[0071] A flexible bend-resistant cable includes a cable core, which is composed of a copper conductor 1 and a cross-linked polyethylene inner sheath 2; an aluminum-plastic composite tape 3 and a mica wrapping tape 4 are sequentially coated outside the cable core, and an outer sheath 5 is coated outside the mica wrapping tape 4.

[0072] The outer sheath 5 comprises the following raw materials in parts by weight: 75 parts of linear low-density polyethylene resin, 10 parts of metallocene linear low-density polyethylene, 22 parts of ethylene-vinyl acetate copolymer, 4.5 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.45 part of wrinkled graphene / nano-carbon sphere composite material, 5.5 parts of inorganic filler, 5 parts of DOPO, 0.2 part of silane coupling agent KH550, 1.8 parts of PE wax, and 0.3 part of antioxidant 1010. The inorganic filler is composed of montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0073] In this example, the structure and preparation method of the wrinkled graphene / nano-carbon sphere composite material are the same as those in Example 1. The preparation method of the pellet for the outer sheath 5 is the same as that in Example 1.

[0074] Example 4

[0075] It is basically the same as Example 1, except that the inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0076] The preparation method of the modified montmorillonite includes the following steps:

[0077] A. Place the montmorillonite in an aqueous ammonium chloride solution with a mass fraction of 35% and ultrasonically mix for 3 h. After standing for precipitation, remove the supernatant on the upper layer of the montmorillonite precipitate, and first place the obtained montmorillonite precipitate in vacuum drying at 60 °C, then in an air atmosphere, heat it to 730 °C at a rate of 6 °C / min and calcine for 3 h. After cooling to room temperature, pulverize it and pass through a 200-mesh sieve to obtain pretreated montmorillonite.

[0078] B. Place 50 g of pretreated montmorillonite in the reaction chamber. First, introduce steam for 10 s. Then introduce argon to remove the steam in the reaction chamber. Next, introduce a mixed gas of argon and titanium tetrachloride gas for 12 s, and then introduce argon to remove the titanium tetrachloride gas in the reaction chamber. Among them, the gas flow rate of steam is 800 sccm; the gas flow rate of argon is 1600 sccm, and the gas flow rate of titanium tetrachloride gas is 800 sccm.

[0079] C. Repeat step B 30 times; and continue to introduce argon to purge the obtained montmorillonite for 30 min to obtain the modified montmorillonite.

[0080] Example 5

[0081] It is basically the same as Example 2, except that the inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0082] The preparation method of the modified montmorillonite includes the following steps:

[0083] A. Place montmorillonite in an aqueous ammonium chloride solution with a mass fraction of 35% and ultrasonically mix for 5 h. After standing and precipitating, remove the supernatant on the upper layer of the montmorillonite precipitate, and first place the obtained montmorillonite precipitate in vacuum drying at 60 °C, then in an air atmosphere, heat it to 750 °C at a rate of 4 °C / min and calcine for 2 h. After cooling to room temperature, pulverize it and pass through a 200-mesh sieve to obtain pretreated montmorillonite.

[0084] B. Place 50 g of pretreated montmorillonite in the reaction chamber. First, introduce steam for 8 s. Then introduce argon to remove the steam in the reaction chamber. Next, introduce a mixed gas of argon and titanium tetrachloride gas for 10 s, and then introduce argon to remove the titanium tetrachloride gas in the reaction chamber. Among them, the gas flow rate of steam is 500 sccm; the gas flow rate of argon is 1500 sccm, and the gas flow rate of titanium tetrachloride gas is 500 sccm.

[0085] C. Repeat step B 35 times; and continue to introduce argon to purge the obtained montmorillonite for 30 min to obtain the modified montmorillonite.

[0086] Comparative Example 1

[0087] It is basically the same as Example 1, except that the outer sheath 5 includes the following raw materials in parts by weight: 70 parts of linear low-density polyethylene resin, 30 parts of metallocene linear low-density polyethylene, 0.5 part of wrinkled graphene / nanocarbon sphere composite material, 5 parts of inorganic filler, 5 parts of DOPO, 0.3 part of silane coupling agent KH550, 1.7 parts of PE wax, and 0.2 part of antioxidant 1010. The inorganic filler is composed of montmorillonite and calcium carbonate in a mass ratio of 1:0.3.

[0088] Comparative Example 2

[0089] It is basically the same as Example 1, except that the wrinkled graphene / nanocarbon sphere composite is replaced by multi-layer graphene oxide.

[0090] Comparative Example 3

[0091] It is basically the same as Example 1, except that the wrinkled graphene / nanocarbon sphere composite is replaced by the wrinkled graphene prepared by the method in Example 1.

[0092] Comparative Example 4

[0093] It is basically the same as Example 1, except that the wrinkled graphene / nanocarbon sphere composite is replaced by a multi-layer graphene oxide / nanocarbon sphere composite;

[0094] The preparation method of the multi-layer graphene oxide / nanocarbon sphere composite includes the following steps:

[0095] Put 30 g of multi-layer graphene oxide into 5 L of a glucose aqueous solution with a concentration of 0.3 mol / L for hydrothermal reaction. The temperature of the hydrothermal reaction is 190 °C, and the time of the hydrothermal reaction is 6 h; after cooling to room temperature, carry out centrifugation, washing, and vacuum drying to obtain the multi-layer graphene oxide / nanocarbon sphere composite.

[0096] Performance Test

[0097] Make specimens from the outer sheath pellets in Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention for performance testing.

[0098] 1. Test the tensile strength and elongation at break according to GB / T1040.1-2018 "Plastics - Determination of tensile properties", and test the flexural strength according to GB / T 9341-2008 "Plastics - Determination of flexural properties". The specific test results are shown in Table 1.

[0099] Table 1:

[0100]

[0101] As can be seen from Table 1, the outer sheath material specimens prepared in Examples 1 to 5 of the present invention have excellent tensile strength, elongation at break, and flexural strength. It can be seen that they not only have high flexibility, but also are resistant to bending and have high strength. By comparing Example 1 with Examples 4 to 5, it can be seen that when using modified montmorillonite as the main filler, the strength and bending resistance of the outer sheath material specimens are both improved.

[0102] It can be seen from the comparison between Example 1 and Comparative Example 1 that adding an appropriate amount of ethylene-vinyl acetate copolymer and ethylene-acrylate-maleic anhydride terpolymer to the outer sheath material can improve the tensile strength, elongation at break and flexural strength of the outer sheath material.

[0103] It can be seen from the comparison between Example 1 and Comparative Example 2 that, compared with multi-layer graphene oxide, using the wrinkled graphene / nanocarbon sphere composite material can significantly improve the tensile strength, elongation at break and flexural strength of the outer sheath material.

[0104] It can be seen from the comparison between Example 1 and Comparative Example 3 that, compared with wrinkled graphene, loading nanocarbon spheres on the surface of wrinkled graphene can effectively improve the tensile strength, elongation at break and flexural strength of the outer sheath material.

[0105] It can be seen from the comparison between Example 1 and Comparative Example 4 that, compared with the multi-layer graphene oxide / nanocarbon sphere composite material, using wrinkled graphene as a carrier and loading nanocarbon spheres on its surface can effectively improve the tensile strength, elongation at break and flexural strength of the outer sheath material.

[0106] 2. The limiting oxygen index was tested according to the ASTM D2863-77 standard; the UL-94 vertical burning level was tested according to GB / T 2408-2008 "Test Method for Flammability of Plastics - Horizontal and Vertical Methods". The specific test results are shown in Table 2.

[0107] Table 2:

[0108]

[0109] It can be seen from Table 2 that the outer sheath material specimens prepared in Examples 1 to 5 of the present invention have good flame retardant properties. Especially when using modified montmorillonite as the main filler, the flame retardant properties of the outer sheath material specimens are significantly enhanced.

[0110] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention 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 recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible bending-resistant cable, comprising an outer sheath, characterized in that: The outer sheath comprises the following raw materials in parts by weight: 65-75 parts of linear low-density polyethylene resin, 10-20 parts of metallocene linear low-density polyethylene, 15-25 parts of ethylene-vinyl acetate copolymer, 3.5-5 parts of ethylene-acrylate-maleic anhydride terpolymer, 0.4-0.65 parts of wrinkled graphene / nano carbon ball composite material, 4.5-6.5 parts of inorganic filler, 4.5-6 parts of flame retardant, 0.1-0.3 parts of silane coupling agent, 1.2-1.8 parts of lubricant, and 0.2-0.5 parts of antioxidant; The preparation method of the wrinkled graphene / nano carbon ball composite material comprises the following steps: S1: adding multilayer graphene oxide and nano-silicon dioxide to water, stirring and mixing, obtaining a graphene oxide / nano-silicon dioxide dispersion; then atomizing the graphene oxide / nano-silicon dioxide dispersion, and using argon as a carrier gas to carry the gas obtained after the atomization into a heating chamber at 850-900°C for heat treatment, and then collecting the obtained composite; placing the composite in a hydrofluoric acid solution, etching away the nano-silicon dioxide, and obtaining the wrinkled graphene after centrifugation, water washing, and vacuum drying; the particle size of the multilayer graphene oxide is 1-10 μm, and the particle size of the nano-silicon dioxide is 10-30 nm; S2: placing the wrinkled graphene in a glucose aqueous solution for hydrothermal reaction; after cooling to room temperature, centrifuging, washing, and vacuum drying are performed to obtain a wrinkled graphene / nanocarbon ball composite material.

2. The flexible bending-resistant cable according to claim 1, characterized in that: In step 1), In the graphene oxide / nano-silicon dioxide dispersion, the concentration of multilayer graphene oxide is 3-6 mg / mL; and the concentration of nano-silicon dioxide is 1.5-3 mg / mL.

3. The flexible bending-resistant cable according to claim 1, characterized in that: In step S2, the concentration of the glucose aqueous solution is 0.2-0.5 mol / L; the temperature of the hydrothermal reaction is 170-190° C., and the time of the hydrothermal reaction is 5-7 h.

4. The flexible bending-resistant cable according to claim 1, characterized in that: The inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.2-0.5 or the inorganic filler is composed of montmorillonite and calcium carbonate in a mass ratio of 1:0.2-0.

5.

5. The flexible bending-resistant cable according to claim 4, characterized in that: The inorganic filler is composed of modified montmorillonite and calcium carbonate in a mass ratio of 1:0.2-0.5; the preparation method of the modified montmorillonite comprises the following steps: A. placing montmorillonite in an aqueous solution of ammonium chloride for ultrasonic mixing, allowing the precipitate to settle, and then vacuum drying the precipitate, and then calcining the precipitate in an air atmosphere; and then crushing and sieving the precipitate to obtain pretreated montmorillonite; B. placing the pretreated montmorillonite in a reaction chamber, first introducing water vapor for 8 to 10 seconds, then introducing argon to remove the water vapor in the reaction chamber, then introducing a mixed gas of argon and titanium tetrachloride gas for 10 to 13 seconds, and then introducing argon to remove the titanium tetrachloride gas in the reaction chamber; C. Repeat step B 25 to 40 times; and continue to introduce argon gas to purge the obtained montmorillonite for 20 to 30 minutes to obtain the modified montmorillonite.

6. The flexible bending-resistant cable according to claim 5, characterized in that: The mass fraction of the ammonium chloride aqueous solution is 30-40%; during the roasting treatment, the temperature is raised to 700-750°C at a rate of 3-6°C / min and roasted for 2-3h; In step B, the gas flow rate of water vapor is 500-1000 sccm; the gas flow rate of argon gas is 1500-2000 sccm, and the gas flow rate of titanium tetrachloride gas is 500-1000 sccm.

7. The flexible bending-resistant cable according to any one of claims 1 to 6, characterized in that: The flame retardant is DOPO.

8. The flexible bending-resistant cable according to any one of claims 1 to 6, characterized in that: The flexible bending-resistant cable comprises a cable core, which is composed of a copper conductor and a cross-linked polyethylene inner sheath; the outer side of the cable core is sequentially coated with an aluminum-plastic composite wrapping tape and a mica wrapping tape, and the outer side of the mica wrapping tape is coated with the outer sheath.

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