Preparation method of novel cable sheath layer

Abstract

The invention provides a preparation method of a novel cable sheath layer. The novel cable sheath layer comprises silicone rubber, a heat-conducting insulating material, a flame-retardant material, white carbon black, a silane coupling agent, dicumyl peroxide, silicone oil, an antioxidant, a light stabilizer and the like. The preparation method comprises the following steps: firstly, modifying a heat-conducting insulating material and a flame-retardant material to improve the dispersity and interfacial compatibility, and then uniformly dispersing filler in a silicone rubber matrix through banburying, open milling and vulcanization processes to finally form a high-performance cable sheath layer. Nanometer spherical aluminum oxide grafted hexagonal boron nitride is used as a heat-conducting insulating material, so that the heat conductivity of the sheath layer is remarkably improved, and excellent electrical insulation performance is kept. Besides, modified magnesium-rich silicate is used as a flame-retardant material, so that the cable has an excellent flame-retardant effect, and an antioxidant and a light stabilizer are combined, so that the weather resistance and the aging resistance of the sheath layer are improved. The prepared cable sheath layer is suitable for the fields of high-voltage cables, 5G communication, power transmission, aerospace, military use, rail transit and the like, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to a novel cable sheath layer and a preparation method thereof, belonging to the technical fields of composite materials and rubber materials. Background Art

[0002] With the rapid development of power, communication, and information technologies, the requirements for cables are also increasing day by day, especially for the performance of their sheath layers. Traditional cable sheath layer materials such as PVC (polyvinyl chloride) and PE (polyethylene) can provide electrical insulation and mechanical protection to a certain extent, but under high voltage, high frequency, and special environmental conditions, their thermal conductivity, electrical insulation, flame retardancy, and weather resistance often cannot meet the requirements. Currently, widely used cable sheath layer materials include PVC, PE, XLPE (crosslinked polyethylene), etc. These materials have low cost, good processability, and basic electrical insulation properties, but are prone to aging under high-temperature environments, have poor chemical corrosion resistance, and also have limited performance in terms of flame retardancy and thermal conductivity. Silicone rubber has become the focus of research for a new generation of cable sheath layer materials due to its excellent thermal conductivity, electrical insulation performance, and good weather resistance. However, traditional silicone rubber has certain limitations in terms of flame retardancy and processability, and is not suitable for some special application scenarios with high requirements. To improve the flame retardancy and processability of silicone rubber, researchers have proposed preparation methods for novel cable sheath layer materials, including adding heat-conducting insulating materials, flame retardants, fumed silica, and other fillers into the silicone rubber matrix, and using specific vulcanization processes and additives to improve its performance. However, how to further improve the thermal conductivity and flame retardancy of silicone rubber has become an urgent problem for scientists to solve. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method for a novel cable sheath layer.

[0004] The purpose of the present invention is achieved through the following technical solutions: A preparation method for a novel cable sheath layer, comprising the following components by weight: 100 parts of silicone rubber; 40 - 50 parts of heat-conducting insulating material; 10 - 15 parts of flame retardant material; 10 - 15 parts of fumed silica; 2 - 3 parts of silane coupling agent (KH-550); 1 - 2 parts of dicumyl peroxide; 10 - 15 parts of silicone oil; 0.5 - 0.8 parts of antioxidant AO-1010; 1 - 2 parts of light stabilizer UV-328; The preparation includes the following steps: (1)Vacuum dry the thermally conductive insulating material, flame retardant filler and silica at 60 °C for 4 - 6 h to remove moisture; (2)Add the silicone rubber matrix into a mixer, and sequentially add the thermally conductive insulating material, flame retardant filler, silica, silicone oil, antioxidant (AO - 1010), and light stabilizer (UV - 328). Control the temperature at 50 - 70 °C and knead for 10 - 15 min to form a kneaded rubber; (3)Then, continue to mix in an open mill to evenly disperse the filler, add dicumyl peroxide (DCP), and further knead for 30 min. After mixing evenly, take out the sheet to obtain the kneaded rubber; (4)Vulcanize the cooled kneaded rubber at 160 - 180 °C with a flat vulcanizer to obtain the cable sheath layer.

[0005] Preferably, the preparation method of the thermally conductive insulating material is as follows: (1)Hexagonal boron nitride is added to H₂O with a mass concentration of 30%, stirred and reacted for 1 h, filtered, washed, and vacuum dried to obtain modified hexagonal boron nitride; the modified hexagonal boron nitride is ultrasonically dispersed in methanol, and ethyleneimine monomer is added. Use sodium hydroxide solution to adjust the pH to 10 - 11 to obtain dispersion A; under nitrogen protection, the ammonium persulfate / methanol solution is dropped into dispersion A, and magnetically stirred and reacted at 60 °C, filtered, washed, and dried to obtain polyethyleneimine - coated hexagonal boron nitride; 2 O 2 (2)Nanospherical Al₂O₃ is dispersed in ethanol, 3 - aminopropyltrimethoxysilane is added, and stirred and reacted at room temperature for 6 - 12 h, filtered, washed, and dried to obtain silane - modified nanospherical alumina; (3)Polyethyleneimine - coated hexagonal boron nitride is dispersed in DMF solution, silane - modified nanospherical alumina is added, magnetically stirred and reacted at 60 °C, filtered, washed, and dried to obtain nanospherical alumina - grafted hexagonal boron nitride, which is the thermally conductive insulating material. 2 O 3 (2)Nanospherical Al₂O₃ is dispersed in ethanol, 3 - aminopropyltrimethoxysilane is added, and stirred and reacted at room temperature for 6 - 12 h, filtered, washed, and dried to obtain silane - modified nanospherical alumina; (3)Polyethyleneimine - coated hexagonal boron nitride is dispersed in DMF solution, silane - modified nanospherical alumina is added, magnetically stirred and reacted at 60 °C, filtered, washed, and dried to obtain nanospherical alumina - grafted hexagonal boron nitride, which is the thermally conductive insulating material.

[0006] Preferably, in the preparation method of the thermally conductive insulating material, the mass ratio of modified hexagonal boron nitride to ethyleneimine monomer in step (1) is (1 - 3) : (5 - 10); the mass ratio of polyethyleneimine - coated hexagonal boron nitride to silane - modified nanospherical alumina in step (3) is (1 - 2) : (1 - 3).

[0007] Preferably, the preparation method of the flame retardant material is as follows: Magnesium - rich silicate is dispersed into a 1% silica sol solution, magnetically stirred for 3 h, heat - treated at 50 °C, filtered, and dried to obtain modified magnesium - rich silicate, which is the flame retardant.

[0008] Preferably, the cable sheath layer has high thermal conductivity, electrical insulation, flame retardancy and weather resistance.

[0009] Preferably, the cable sheath layer is applied in cable fields such as high voltage, 5G communication, aerospace and military, and rail transit.

[0010] Basic principle of the present invention: (1) Hexagonal boron nitride is oxidized and modified with hydrogen peroxide to improve its surface activity, and then polyethyleneimine (PEI) is wrapped on its surface to enhance its dispersibility and interfacial compatibility in the composite material; 3-aminopropyltrimethoxysilane is used to perform silanization modification on nano-spherical alumina to make its surface have better chemical stability and affinity, thereby optimizing the dispersibility and uniformity of the material; finally, hexagonal boron nitride is grafted onto nano-spherical alumina, thus greatly improving the dispersibility of alumina in the polymer system.

[0011] (2) By wrapping magnesium-rich silicate with silica, the compatibility of the flame retardant magnesium-rich silicate in the system is improved.

[0012] (3) By adding thermally conductive and insulating materials such as nano-spherical alumina grafted with hexagonal boron nitride to the silicone rubber matrix, the thermal conductivity of the sheath layer is improved, while ensuring its electrical insulation performance to meet the requirements of fields such as high voltage and 5G communication; modified magnesium-rich silicate is used as a flame retardant filler, combined with a light stabilizer and an antioxidant, to improve the high temperature resistance, anti-aging and flame retardant properties of the material, so that it can still maintain stability in extreme environments.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) By using the highly thermally conductive and insulating material of nano-spherical alumina grafted with hexagonal boron nitride, the cable sheath layer has both high thermal conductivity and excellent electrical insulation performance, meeting the requirements for high-performance cables in fields such as high voltage, 5G communication, and aerospace.

[0014] (2) Using modified magnesium-rich silicate as a flame retardant filler, combined with an antioxidant and a light stabilizer, enables the sheath layer to remain stable in harsh environments such as high temperature, humidity, and ultraviolet radiation, and has more excellent flame retardant performance and anti-aging ability, improving the safety and service life of the cable. Description of the drawings

[0015] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious: Figure 1 It is the preparation flow chart of the new cable sheath layer prepared in Example 1 of the present invention. Detailed implementation manners

[0016] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention. Example 1

[0017] This example relates to a preparation method of a new type of cable sheath layer, which specifically includes the following steps: Weigh the raw materials according to the following ratio: Silicone rubber: 100 parts; Thermal conductive insulating material: 45 parts; Flame retardant material: 15 parts; Fumed silica: 12 parts; Silane coupling agent (KH-550): 2.5 parts; Dicumyl peroxide: 2 parts; Silicone oil: 12 parts; Antioxidant AO-1010: 0.6 part; Light stabilizer UV-328: 2 parts; Vacuum dry the thermal conductive insulating material, flame retardant filler and fumed silica at 60 °C for 6 h to remove moisture; add the silicone rubber matrix into the internal mixer, and then sequentially add the thermal conductive insulating material, flame retardant filler, fumed silica, silicone oil, antioxidant (AO-1010), and light stabilizer (UV-328). Control the temperature at 50 °C and knead for 15 min to form a kneaded rubber; then, continue to mix in the open mill to make the filler evenly dispersed, add dicumyl peroxide (DCP), and further knead for 30 min. After mixing evenly, take out the sheet to obtain the kneaded rubber; vulcanize the cooled kneaded rubber at 170 °C by a flat vulcanizer to obtain the cable sheath layer.

[0018] The tensile strength of the cable sheath layer prepared in Example 1 is 16.7 MPa, the elongation at break is 208.1%, the thermal elongation is 80.4%, the volume resistance is 5.1×10 11 Ω, the oxygen index is 32.1, and the thermal conductivity is 1.21 W / m·K. Example 2

[0019] This example relates to a preparation method of a new type of cable sheath layer, which specifically includes the following steps: Weigh the raw materials according to the following ratio: Silicone rubber: 100 parts; Thermal conductive insulating material: 40 parts; Flame retardant material: 12 parts; Fumed silica: 15 parts; 1.5 parts of silane coupling agent (KH-550); 1.8 parts of dicumyl peroxide; 13 parts of silicone oil; 0.7 part of antioxidant AO-1010; 2.2 parts of light stabilizer UV-328; The thermal conductive insulating material, flame retardant filler and silica white were vacuum dried at 60 °C for 6 h to remove moisture; the silicone rubber matrix was added to an internal mixer, and then the thermal conductive insulating material, flame retardant filler, silica white, silicone oil, antioxidant (AO-1010), and light stabilizer (UV-328) were added in sequence. The temperature was controlled at 55 °C and kneaded for 15 min to form a kneaded rubber; then, it was continuously mixed in an open mill to uniformly disperse the filler, dicumyl peroxide (DCP) was added, and further kneaded for 30 min. After mixing evenly, a sheet was taken out to obtain the kneaded rubber; the cooled kneaded rubber was vulcanized at 175 °C by a flat vulcanizer to obtain a cable sheath layer.

[0020] The tensile strength of the cable sheath layer prepared in Example 2 was 17.8 MPa, the elongation at break was 232.1%, the thermal elongation was 81.9%, the volume resistance was 5×10 11 Ω, the oxygen index was 33.2, and the thermal conductivity was 1.31 W / m·K. Example 3

[0021] This example relates to a preparation method of a novel cable sheath layer, which specifically includes the following steps: Ingredients were proportioned according to the following raw material ratio: 100 parts of silicone rubber; 48 parts of thermal conductive insulating material; 13 parts of flame retardant material; 14 parts of silica white; 2 parts of silane coupling agent (KH-550); 2 parts of dicumyl peroxide; 13 parts of silicone oil; 0.7 part of antioxidant AO-1010; 1.5 parts of light stabilizer UV-328; The thermally conductive insulating material, flame retardant filler and silica white were vacuum dried at 60 °C for 6 h to remove moisture; the silicone rubber matrix was added to a mixer, and then the thermally conductive insulating material, flame retardant filler, silica white, silicone oil, antioxidant (AO-1010), and light stabilizer (UV-328) were added in sequence. The temperature was controlled at 60 °C and kneaded for 15 min to form a kneaded rubber; then, it was continuously mixed in an open mill to uniformly disperse the filler, and dicumyl peroxide (DCP) was added and further kneaded for 30 min. After mixing evenly, a sheet was taken out to obtain the kneaded rubber; the kneaded rubber after cooling was vulcanized at 170 °C by a flat vulcanizer to obtain the cable sheath layer.

[0022] The tensile strength of the cable sheath layer prepared in Example 3 was 16.3 MPa, the elongation at break was 227.1%, the thermal elongation was 84.1%, the volume resistivity was 4.9×10 11 Ω, the oxygen index was 30.9, and the thermal conductivity was 1.18 W / m·K. Example 4

[0023] This example relates to a preparation method of a novel cable sheath layer, and the preparation method of the thermally conductive insulating material is as follows: 1 g of hexagonal boron nitride was added to 100 mL of H 2 O 2 (mass concentration 30%), stirred for 1 h, filtered, washed, and vacuum dried to obtain modified hexagonal boron nitride; 1 g of modified hexagonal boron nitride was ultrasonically dispersed in 100 mL of methanol, 5 g of ethyleneimine monomer was added, and the pH was adjusted to 11 using a sodium hydroxide solution to obtain dispersion A; nitrogen was introduced into the system for protection, 0.2 g of ammonium persulfate was dissolved in 10 mL of methanol, and the ammonium persulfate solution was added dropwise to dispersion A. The reaction was magnetically stirred at 60 °C for 6 h, filtered, washed, and dried to obtain polyethyleneimine-coated hexagonal boron nitride. 0.5 g of nano-spherical Al 2 O 3 was added to 100 mL of absolute ethanol, ultrasonically dispersed, 0.5 g of 3-aminopropyltrimethoxysilane was added, and the reaction was stirred at room temperature for 10 h, filtered, washed, and dried to obtain silane-modified nano-spherical alumina.

[0024] 0.5 g of polyethyleneimine-coated hexagonal boron nitride was dispersed in 100 mL of DMF solution, 0.6 g of silane-modified nano-spherical alumina was added, and the reaction was magnetically stirred at 60 °C for 12 h, filtered, washed, and dried to obtain nano-spherical alumina grafted with hexagonal boron nitride. Example 5

[0025] This example relates to a preparation method of a novel cable sheath layer, and the preparation method of the flame retardant material is as follows: 1 g of magnesium-rich silicate was dispersed into a silica sol solution with a mass concentration of 1%, magnetically stirred for 3 h, heat-treated at 50 °C, filtered and dried to obtain the modified magnesium-rich silicate, i.e., the flame retardant described above. Comparative Example 1

[0026] The difference from Example 1 is that in the preparation method, "thermal conductive insulating material" was replaced with commercially available "aluminum oxide". The tensile strength of the finally obtained cable sheath layer was 13.1 MPa, the elongation at break was 168.1%, the thermal elongation was 80.9%, the volume resistance was 5.3×10 11 Ω, the oxygen index was 30.1, and the thermal conductivity was 1.11 W / m·K. Comparative Example 2

[0027] The difference from Example 1 is that in the preparation method, "thermal conductive insulating material" was replaced with commercially available "hexagonal boron nitride". The tensile strength of the finally obtained cable sheath layer was 17.1 MPa, the elongation at break was 209.1%, the thermal elongation was 83.9%, the volume resistance was 5.3×10 11 Ω, the oxygen index was 28.8, and the thermal conductivity was 0.57 W / m·K.

[0028] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a novel cable sheath layer, characterized in that: It includes the following components by weight: Silicone rubber 100 parts; 40~50 parts of thermal conductive insulating material; 10~15 parts of flame retardant materials; 10-15 parts of white carbon black; Silane coupling agent (KH-550) 2~3 parts; 1-2 parts of dicumyl peroxide; Silicone oil 10-15 parts; Antioxidant AO-1010 0.5~0.8 parts; Light stabilizer UV-328 1~2 parts; The preparation method of the cable sheath layer is: (1) The thermal conductive insulating material, the flame retardant material and the white carbon black are vacuum dried at 60 °C for 4 to 6 h to remove moisture; (2) Add silicone rubber matrix into an internal mixer, and then add thermal conductive insulating material, flame retardant filler, white carbon black, silicone oil, antioxidant (AO-1010), and light stabilizer (UV-328) in sequence, and mix at a temperature of 50-70 °C for 10-15 min to form a mixed rubber; (3) Continue mixing in an open mill to evenly disperse the filler, add dicumyl peroxide (DCP), and further mix for 30 minutes. After mixing evenly, flake out to obtain a mixed rubber; (4) vulcanizing the cooled rubber mixture at 160-180 °C on a flat vulcanizer to obtain a cable sheath layer; The preparation method of the thermally conductive insulating material is as follows: (1) Take hexagonal boron nitride, add H2O2 with a mass concentration of 30%, stir and react for 1 h, filter, wash and vacuum dry to obtain modified hexagonal boron nitride; ultrasonically disperse the modified hexagonal boron nitride in methanol, add ethyleneimine monomer, and use sodium hydroxide solution to adjust the pH to 10-11 to obtain dispersion A; under nitrogen protection, add ammonium persulfate / methanol solution dropwise to dispersion A, react with magnetic stirring at 60 °C, filter, wash and dry to obtain polyethyleneimine-coated hexagonal boron nitride; (2) Dispersing nano-spherical Al2O3 in ethanol, adding 3-aminopropyltrimethoxysilane, stirring at room temperature for 6-12 h, filtering, washing, and drying to obtain silane-modified nano-spherical alumina; (3) Polyethyleneimine-wrapped hexagonal boron nitride is dispersed in a DMF solution, silane-modified nano-spherical alumina is added, and the reaction is carried out under magnetic stirring at 60° C., and the reaction is carried out after filtering, washing, and drying to obtain nano-spherical alumina grafted hexagonal boron nitride, i.e., the thermal conductive insulating material; The mass ratio of the modified hexagonal boron nitride and ethyleneimine monomer in step (1) is (1-3): (5-10); In step (3), the mass ratio of the polyethyleneimine-coated hexagonal boron nitride and the silane-modified nano-spherical alumina is (1-2): (1-3); The preparation method of the flame retardant material is as follows: The magnesium-rich silicate was dispersed in a silica sol solution with a mass concentration of 1%, magnetically stirred for 3 h, heated at 50°C, filtered and dried to obtain the modified magnesium-rich silicate, namely the flame retardant.

2. A method for preparing a novel cable sheath layer as claimed in claim 1, characterized in that: The cable sheath layer has high thermal conductivity, electrical insulation, flame retardancy and weather resistance.

3. The method for preparing a novel cable sheath layer according to claim 1, characterized in that: The cable sheath layer is used in high voltage, 5G communication, aerospace, rail transportation and other fields.

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