A lightweight and aging-resistant cable sheath material based on expandable microspheres and its preparation method

Abstract

The present invention relates to a lightweight and aging-resistant cable sheath material based on expandable microspheres and a preparation method thereof, comprising the following raw materials in parts by weight: 63-75 parts of ethylene propylene diene monomer (EPDM), 22-32 parts of chlorinated polyethylene, 13-21 parts of expandable microspheres, 6-8 parts of processing aids, 5-7 parts of zinc oxide, 2-4 parts of vulcanizing agent, and 0.3-0.5 part of co-crosslinking agent; taking EPDM as the main body endows the material with excellent anti-aging performance; among them, chlorinated polyethylene can enhance the aging resistance of the material; among them, expandable microspheres can lighten the sheath material and improve the aging resistance of the material; one of the raw materials added to the expandable microspheres is modified boron nitride containing a variety of functional groups, which significantly enhances the mechanical properties and aging resistance of the material, and the performance is stable; the present invention has the advantages of good anti-aging performance, strong aging resistance, lightweight, and reduced agglomeration phenomenon.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable materials, and particularly relates to a lightweight and aging-resistant cable sheath material based on expandable microspheres and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry and technology, cables, as important carriers for power transmission and signal transmission, play an indispensable role in various fields. A cable generally consists of a conductor, an insulating material, and a cable sheath. Among them, the cable sheath has the greatest impact on the performance of the cable. Traditional cable sheath materials mostly use high molecular materials such as polyvinyl chloride (PVC), polyethylene (PE), or cross-linked polyethylene (XLPE). These materials are widely used due to their good insulation, processability, and cost advantages. However, traditional materials are prone to performance degradation during long-term service, and their aging resistance is insufficient. Expandable microspheres, as a new type of functional filler, have shown great application potential in the field of lightweight composite materials in recent years. However, the current application research on expandable microspheres in cable sheath materials is still in its initial stage, and there are still some key problems to be solved. First, the commonly used polymer matrices of expandable microspheres include acrylic resin, phenolic resin, styrene and vinylidene chloride copolymer, etc. These polymer matrices generally have poor mechanical properties. Therefore, it is urgent to solve the above problems to meet the higher requirements of the cable material technology field. Therefore, it is very necessary to provide a lightweight and aging-resistant cable sheath material based on expandable microspheres and a preparation method thereof, which has good anti-aging performance, strong aging resistance, lightweight, and reduced agglomeration phenomenon. Summary of the Invention

[0003] (I) Technical Problems

[0004] In view of the above-mentioned current situation of the prior art, the present application mainly aims at the following technical problems:

[0005] 1. Traditional cable sheath materials are prone to performance degradation during long-term service, and their aging resistance is insufficient.

[0006] 2. Although the new type of functional filler expandable microspheres has great application potential, its application in cable sheath materials is in the initial research stage, and there are some key problems that need to be solved.

[0007] 3. The commonly used polymer matrices of expandable microspheres generally have poor mechanical properties and cannot meet the higher requirements of cable materials.

[0008] (II) Technical Solutions

[0009] The object of the present invention is to overcome the deficiencies of the prior art, and to provide a lightweight and aging-resistant cable sheath material based on expandable microspheres and a preparation method thereof, which has good anti-aging performance, strong aging resistance, lightweight property, and reduced agglomeration phenomenon.

[0010] The object of the present invention is achieved as follows: A lightweight and aging-resistant cable sheath material based on expandable microspheres and a preparation method thereof, comprising the following raw materials in parts by weight: 63-75 parts of ethylene propylene diene monomer (EPDM), 22-32 parts of chlorinated polyethylene, 13-21 parts of expandable microspheres, 6-8 parts of processing aids, 5-7 parts of zinc oxide, 2-4 parts of vulcanizing agent, 0.3-0.5 part of co-crosslinking agent.

[0011] A preparation method of a lightweight and aging-resistant cable sheath material based on expandable microspheres, comprising the following steps:

[0012] Add EPDM and chlorinated polyethylene into an open mill, after primary mixing, then add expandable microspheres, processing aids, zinc oxide, vulcanizing agent and co-crosslinking agent, conduct secondary mixing, and after the mixing is completed, vulcanize to obtain a lightweight and aging-resistant cable sheath material based on expandable microspheres.

[0013] Further, the vulcanizing agent is dicumyl peroxide; the co-crosslinking agent is one of triallyl cyanurate and triallyl isocyanurate; the processing aid is one of zinc stearate, white paraffin wax, stearic acid and polyethylene wax.

[0014] Further, the time of both the primary mixing and the secondary mixing is 5-10 min.

[0015] In the present invention, EPDM is used as the main raw material of the material. EPDM has excellent ozone resistance and ultraviolet resistance, endowing the material with excellent anti-aging performance; chlorinated polyethylene is added to the raw materials, which has good compatibility with EPDM, and their vulcanization properties are similar, which can further enhance the aging resistance of the material; adding zinc oxide to the raw materials can improve the crosslinking density of the finished product and promote vulcanization.

[0016] The raw materials of the expandable microspheres are as follows in parts by weight: 23-31 parts of methyl methacrylate, 19-25 parts of butyl acrylate, 20-28 parts of methacrylic acid, 4-6 parts of emulsifier, 80-100 parts of deionized water, 8-16 parts of modified boron nitride, 0.2-0.4 part of potassium persulfate.

[0017] Further, the expandable microspheres are prepared through the following steps:

[0018] A1: Add methyl methacrylate, butyl acrylate, methacrylic acid, and an emulsifier to deionized water, mix and stir well, then add modified boron nitride, mechanically stir for 20 - 30 min, and then place it in an ice bath and ultrasonicate for 10 - 20 min to form an emulsion.

[0019] A2: Add potassium persulfate (initiator) to the emulsion, and introduce nitrogen as a protective gas. In a water bath at 60 - 80 °C, mechanically stir and react for 12 - 24 h to obtain a product. After centrifuging the product, wash and dry it to obtain expanded microspheres.

[0020] Further, the emulsifier is one of alkylphenol polyoxyethylene ether and sodium dodecyl sulfate.

[0021] In the present invention, Pickering emulsion polymerization is used to prepare expanded microspheres with a core - shell structure. After heat treatment, the internal part of these core - shell - structured expanded microspheres will expand to form a hollow microsphere structure. This structure can not only lighten the sheath material but also block oxygen in the external environment and improve the anti - aging performance.

[0022] The modified boron nitride is prepared through the following steps:

[0023] Step 1: Mix γ - aminopropyltriethoxysilane (silane coupling agent KH - 550) with an ethanol - aqueous solution (volume ratio of ethanol / water is 4:1), add acetic acid solution (mass fraction 10%) to adjust the pH of the system to 4 - 5, stir at room temperature for 20 min to fully hydrolyze γ - aminopropyltriethoxysilane; then add boron nitride, and stir and react in a constant - temperature water bath at 60 °C for 6 h. After the reaction is completed, centrifuge and separate, wash with absolute ethanol multiple times, vacuum - dry, and grind to obtain silane - modified boron nitride.

[0024] In the present invention, boron nitride is modified by γ - aminopropyltriethoxysilane, introducing amino groups for subsequent reactions to obtain silane - modified boron nitride.

[0025] Step 2: Add pentaerythritol and toluene into a three - necked flask equipped with a thermometer, an electromagnetic stirrer, a spherical condenser, and a tail gas treatment device. Slowly drip phosphorus trichloride into the flask using a constant - pressure dropping funnel. After dropping, heat the device. When the temperature reaches 78 °C, keep the temperature constant and reflux for 3 h. After the reaction is completed, remove the solvent benzene and excess phosphorus trichloride by vacuum distillation to obtain intermediate product 1.

[0026] In the present invention, pentaerythritol and phosphorus trichloride react. By adjusting the molar ratio of pentaerythritol to phosphorus trichloride to be close to 1:2 (phosphorus trichloride is slightly in excess), intermediate product 1 is obtained; the specific reaction is as Figure 1 shown.

[0027] Step 3: Add intermediate product 1 and acetone into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. Then dissolve 2,4-dihydroxybenzophenone and sodium hydroxide in acetone and distilled water respectively. After stirring and mixing evenly, add them into the flask in sequence. Heat the device. When the temperature reaches 60 °C, keep the temperature constant and reflux for 4 h. After the reaction is completed, perform suction filtration. Wash the filter residue with distilled water and ethanol for multiple times to obtain intermediate product 2;

[0028] In the present invention, sodium hydroxide can react with the hydroxyl group at the para position in the 2,4-dihydroxybenzophenone molecule to form a phenolate with stronger nucleophilicity. The phenolate can attack the carbon atom connected to the chlorine atom on intermediate product 1 to generate an ether bond. By adjusting the molar ratio of 2,4-dihydroxybenzophenone to intermediate product 1 to be close to 1:1 (intermediate product 1 is slightly in excess), it can be ensured that only one chlorine atom in the intermediate product 1 molecule undergoes a substitution reaction, thereby generating intermediate product 2. The specific reaction process is as Figure 2 shown.

[0029] Step 4: Mix silane-modified boron nitride and N,N-dimethylformamide, and perform ultrasonic treatment to make the silane-modified boron nitride disperse evenly. Then add intermediate product 2 and triethylamine. At room temperature, stir magnetically for 4 h, then in a water bath at 55 °C, perform ultrasonic treatment for 4 h, and then remove the water bath and stir magnetically at room temperature for 6 h. After the reaction is completed, perform suction filtration. Take the filter residue, wash it with anhydrous ethanol for multiple times, dry it, and grind it to obtain modified boron nitride.

[0030] In the present invention, the chloro group in the intermediate product 2 molecule undergoes a nucleophilic substitution reaction with the amino group on the silane-modified boron nitride. Triethylamine acts as an acid-binding agent to catalyze the reaction to obtain modified boron nitride.

[0031] Further, the dosage ratio of γ-aminopropyltriethoxysilane, ethanol aqueous solution, and boron nitride in step 1 is 9.6 g:50 mL:1 g.

[0032] Further, the dosage ratio of pentaerythritol, toluene, and phosphorus trichloride in step 2 is 13.6 g:100 mL:29.2 g.

[0033] Further, the dosage ratio of intermediate product 1, acetone, 2,4-dihydroxybenzophenone, sodium hydroxide, and distilled water in step 3 is 28.3 g:100 mL:21.5 g:3.9 g:20 mL.

[0034] Further, the dosage ratio of silane-modified boron nitride, N,N-dimethylformamide, intermediate product 2, and triethylamine in step 4 is 1 g:100 mL:8.6 g:4.2 g.

[0035] In the present invention, boron nitride is formed by alternating arrangement of boron and nitrogen atoms to form a hexagonal lattice, which has excellent thermal stability and mechanical properties. Through the co-modification with silane coupling agent and intermediate product 2, the hydrophobicity of boron nitride is greatly improved, the dispersion in the matrix is promoted, and the agglomeration phenomenon is alleviated. Therefore, the properties of the modified boron nitride are more easily exerted, enhancing the mechanical properties and heat aging resistance of the matrix. By modifying boron nitride, the migration resistance of small molecule intermediate product 2 is also improved.

[0036] In addition, the modified boron nitride molecule also contains phosphite, benzophenone and pentaerythritol structures. Among them, phosphite is a kind of auxiliary antioxidant, which can play an antioxidant role by decomposing peroxides and chelating metal ions, thereby protecting the polymer material from thermal oxygen aging during processing and use.

[0037] In addition, benzophenone contains a carbonyl (C=O) functional group. It can not only absorb ultraviolet light with a wavelength range of 280 - 380 nm, but also transfer energy with the excited state molecules in the polymer material, converting them into stable ground state molecules, and can play a synergistic role with phosphite, greatly enhancing the anti-aging performance of the matrix.

[0038] Finally, the molecule contains a pentaerythritol skeleton, and this unique chemical structure can improve the thermal stability of the matrix.

[0039] (III) Beneficial Effects

[0040] 1. The sheath material prepared by the present invention uses ethylene-propylene-diene monomer rubber as the main raw material, endowing the material with excellent anti-aging performance.

[0041] 2. Chlorinated polyethylene is added to the raw materials to further enhance the aging resistance of the material.

[0042] 3. The self-made expandable microspheres are added to the raw materials, which can not only lighten the sheath material, but also improve the aging resistance of the material.

[0043] 4. Modified boron nitride containing multiple functional groups is added to the self-made expandable microspheres as one of the raw materials. Compared with ordinary boron nitride, it is more easily dispersed, the agglomeration phenomenon is alleviated, and the modified boron nitride also contains multiple functional groups, significantly enhancing the mechanical properties and aging resistance of the material, and the performance is stable.

[0044] In summary, the sheath material prepared by the present invention has stable and efficient aging resistance and mechanical properties, and has important application value in the field of cable material technology. The present invention has the advantages of good anti-aging performance, strong aging resistance, light weight, and alleviated agglomeration phenomenon. Brief Description of the Drawings

[0045] Figure 1Schematic diagram of chemical reaction of Intermediate Product 1 of the present invention.

[0046] Figure 2 Schematic diagram of chemical reaction of Intermediate Product 2 of the present invention.

[0047] Figure 3 Graph showing the test results of relevant properties of the examples and comparative examples of the present invention. Detailed implementation manners

[0048] Expansion microspheres are thermoplastic polymer microspheres containing volatile substances inside. When heated to a certain temperature, the gas inside the microspheres expands, causing their volume to increase rapidly and form a closed-cell structure. This structure can block oxygen, moisture, and other corrosive media in the external environment, helping to delay the aging process of materials and extend the service life of cables. In addition, introducing expansion microspheres into cable sheath materials can also effectively reduce the weight of the materials and make the cables lightweight.

[0049] The present invention will be further described below in conjunction with examples and / or drawings. Example 1

[0050] As Figures 1-3 shown, prepare modified boron nitride:

[0051] Step 1: Mix 9.6 g of γ-aminopropyltriethoxysilane with 50 mL of an ethanol aqueous solution (volume ratio of ethanol / water is 4:1), add acetic acid solution (mass fraction 10%) to adjust the pH of the system to 4, stir at room temperature for 20 min to fully hydrolyze γ-aminopropyltriethoxysilane; then add 1 g of boron nitride, and stir and react in a constant temperature water bath at 60 °C for 6 h. After the reaction is completed, centrifuge and separate, wash with absolute ethanol multiple times, dry in vacuum, and grind to obtain silane-modified boron nitride;

[0052] Step 2: Add 13.6 g of pentaerythritol and 100 mL of toluene into a three-necked flask equipped with a thermometer, an electromagnetic stirrer, a spherical condenser, and a tail gas treatment device. Slowly add 29.2 g of phosphorus trichloride to the flask using a constant pressure dropping funnel. After the addition is complete, heat the device. When the temperature reaches 78 °C, keep the temperature constant and reflux for 3 h. After the reaction is completed, remove the solvent benzene and excess phosphorus trichloride by vacuum distillation to obtain Intermediate Product 1;

[0053] Step 3: Add 28.3 g of intermediate 1 and 50 mL of acetone into a three-necked flask equipped with a magnetic stirrer, a condenser and a thermometer. Then dissolve 21.5 g of 2,4-dihydroxybenzophenone and 3.9 g of sodium hydroxide in 50 mL of acetone and 20 mL of distilled water respectively. After stirring and mixing evenly, add them into the flask in sequence. Heat the device. When the temperature reaches 60 °C, keep the temperature constant and reflux for 4 h. After the reaction is completed, perform suction filtration. Wash the filter residue with distilled water and ethanol for several times to obtain intermediate 2;

[0054] Step 4: Mix 1 g of silane-modified boron nitride and 100 mL of N,N-dimethylformamide, and ultrasonically treat to make the silane-modified boron nitride disperse evenly. Then add 8.6 g of intermediate 2 and 4.2 g of triethylamine. Stir magnetically at room temperature for 4 h, then ultrasonically treat in a water bath at 55 °C for 4 h, and then remove the water bath and stir magnetically at room temperature for 6 h. After the reaction is completed, perform suction filtration. Take the filter residue, wash it with anhydrous ethanol for several times, dry it, and grind it to obtain modified boron nitride. Example 2

[0055] Preparation of expandable microspheres:

[0056] A1: Add 23 g of methyl methacrylate, 19 g of butyl acrylate, 20 g of methacrylic acid and 4 g of sodium dodecyl sulfate into 80 g of deionized water, mix and stir evenly. Then add 8 g of the modified boron nitride prepared in Example 1. After mechanical stirring for 20 min, place it in an ice bath and ultrasonically treat for 10 min to form an emulsion;

[0057] A2: Add 0.2 g of potassium persulfate to the emulsion, and introduce nitrogen as a protective gas. In a water bath at 60 °C, stir mechanically for 12 h to obtain a product. After centrifuging the product, wash it with pure water and ethanol for several times, and dry it to obtain expandable microspheres. Example 3

[0058] Preparation of expandable microspheres:

[0059] A1: Add 31 g of methyl methacrylate, 25 g of butyl acrylate, 28 g of methacrylic acid and 6 g of alkylphenol polyoxyethylene ether into 100 g of deionized water, mix and stir evenly. Then add 16 g of the modified boron nitride prepared in Example and dry it to obtain expandable microspheres.1. After mechanical stirring for 30 min, place it in an ice bath and ultrasonically treat for 20 min to form an emulsion;

[0060] A2: Add 0.4 g of potassium persulfate to the emulsion, and introduce nitrogen as a protective gas. In a water bath at 80 °C, stir mechanically for 24 h to obtain a product. After centrifuging the product, wash it with pure water and ethanol for several times, and dry it to obtain expandable microspheres. Example 4

[0061] Preparation of a lightweight and aging-resistant cable sheath material based on expandable microspheres:

[0062] Add 63 g of ethylene propylene diene monomer rubber and 22 g of chlorinated polyethylene into an open mill. At 100 °C, conduct the first mixing for 5 min, then add 13 g of expandable microspheres prepared in Example 2, 6 g of zinc stearate, 5 g of zinc oxide, 2 g of dicumyl peroxide, and 0.3 g of triallyl cyanurate. At 140 °C, conduct the second mixing for 5 min. After the mixing is completed, obtain the mixed rubber. Vulcanize the mixed rubber in a flat vulcanizer to obtain the lightweight and aging-resistant cable sheath material based on expandable microspheres. Example 5

[0063] Preparation of a lightweight and aging-resistant cable sheath material based on expandable microspheres:

[0064] Add 69 g of ethylene propylene diene monomer rubber and 27 g of chlorinated polyethylene into an open mill. At 110 °C, conduct the first mixing for 10 min, then add 17 g of expandable microspheres prepared in Example 2, 7 g of white paraffin wax, 6 g of zinc oxide, 3 g of dicumyl peroxide, and 0.4 g of triallyl isocyanurate. At 150 °C, conduct the second mixing for 10 min. After the mixing is completed, obtain the mixed rubber. Vulcanize the mixed rubber in a flat vulcanizer to obtain the lightweight and aging-resistant cable sheath material based on expandable microspheres. Example 6

[0065] Preparation of a lightweight and aging-resistant cable sheath material based on expandable microspheres:

[0066] Add 75 g of ethylene propylene diene monomer rubber and 32 g of chlorinated polyethylene into an open mill. At 120 °C, conduct the first mixing for 10 min, then add 21 g of expandable microspheres prepared in Example 2, 8 g of polyethylene wax, 7 g of zinc oxide, 4 g of dicumyl peroxide, and 0.5 g of triallyl isocyanurate. At 160 °C, conduct the second mixing for 10 min. After the mixing is completed, obtain the mixed rubber. Vulcanize the mixed rubber in a flat vulcanizer to obtain the lightweight and aging-resistant cable sheath material based on expandable microspheres.

[0067] Comparative Example 1

[0068] Use commercially available anti-aging agents of the same mass to replace the modified boron nitride in Example 3, and keep the remaining steps unchanged. First, prepare expandable microspheres. Take the expandable microspheres of the same mass and replace the expandable microspheres in Example 6, and keep the remaining steps unchanged to prepare the material.

[0069] Comparative Example 2

[0070] Use ordinary boron nitride of the same mass to replace the modified boron nitride in Example 3, and keep the remaining steps unchanged. First, prepare expandable microspheres. Take the expandable microspheres of the same mass and replace the expandable microspheres in Example 6, and keep the remaining steps unchanged to prepare the material.

[0071] Comparative Example 3

[0072] A commercially available ethylene propylene diene monomer (EPDM) cable compound was used.

[0073] Comparative experiment analysis:

[0074] Examples 4, 5, and 6 and Comparative Examples 1, 2, and 3 were made into corresponding shapes according to different test standards, and the following performance tests were carried out:

[0075] ① The tensile strength was measured using the national standard GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber".

[0076] ② The tensile strength of the aged specimen (GB / T 528-2009) was measured using the national standard GB / T 16585 "Test Method for Artificial Weathering (Fluorescent UV Lamp) of Vulcanized Rubber", and the tensile strength retention rate was calculated; Tensile strength retention rate = Tensile strength after testing / Tensile strength before testing × 100%;

[0077] The specimen was placed in an environment of 160 °C, thermally oxidized in hot air for 48 h, and then the tensile strength (GB / T 528-2009) was measured, and the tensile strength retention rate was calculated;

[0078] ③ The oxidation induction time was measured using the national standard GB / T 19466.6-2009.

[0079] The measured results are as Figure 3 shown; It can be seen from Figure 3 that the sheath material prepared in the examples of the present invention has higher performance in all aspects due to the addition of expandable microspheres compared with the comparative examples. Therefore, the present invention has important application value in the technical field of cable compounds.

[0080] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0081] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A lightweight and aging-resistant cable sheath material based on expandable microspheres, characterized in that: It comprises raw materials in the following parts by weight: 63 - 75 parts of ethylene propylene diene monomer rubber, 22 - 32 parts of chlorinated polyethylene, 13 - 21 parts of expandable microspheres, 6 - 8 parts of processing aids, 5 - 7 parts of zinc oxide, 2 - 4 parts of vulcanizing agent, 0.3 - 0.5 part of co-crosslinking agent; The raw materials of the expandable microspheres are as follows by parts by weight: 23 - 31 parts of methyl methacrylate, 19 - 25 parts of butyl acrylate, 20 - 28 parts of methacrylic acid, 4 - 6 parts of emulsifier, 80 - 100 parts of deionized water, 8 - 16 parts of modified boron nitride, 0.2 - 0.4 part of potassium persulfate; The modified boron nitride is prepared through the following steps: Step 1: Mix γ-aminopropyltriethoxysilane with an ethanol aqueous solution, adjust the pH of the system to 4 - 5, stir at room temperature for 20 min, then add boron nitride, and stir and react at 60 °C for 6 h. After the reaction is completed, silane-modified boron nitride is obtained; Step 2: Add pentaerythritol and toluene into a flask, dropwise add phosphorus trichloride into the flask. After the dropping is completed, reflux and react at 78 °C for 3 h. After the reaction is completed, carry out reduced pressure distillation to obtain intermediate product 1; Step 3: Add intermediate product 1 and acetone into a flask. Dissolve 2,4-dihydroxybenzophenone and sodium hydroxide in acetone and distilled water respectively. After stirring and mixing, add them into the flask in sequence, and reflux and react at 60 °C for 4 h. After the reaction is completed, intermediate product 2 is obtained; Step 4: Mix silane-modified boron nitride and N,N-dimethylformamide, carry out ultrasonic treatment, then add intermediate product 2 and triethylamine. At room temperature, stir magnetically for 4 h, carry out ultrasonic treatment at 55 °C for 4 h, and then stir at room temperature for 6 h. After the reaction is completed, modified boron nitride is obtained.

2. The lightweight and aging-resistant cable sheath material based on expandable microspheres according to claim 1, wherein: The expandable microspheres are prepared through the following steps: A1: Add methyl methacrylate, butyl acrylate, methacrylic acid and emulsifier into deionized water, mix and stir evenly, then add modified boron nitride. After mechanical stirring for 20 - 30 min, place it in an ice bath and carry out ultrasonic treatment for 10 - 20 min to form an emulsion; A2: Add potassium persulfate to the emulsion, and introduce nitrogen as a protective gas. In a water bath at 60 - 80 °C, carry out mechanical stirring and reaction for 12 - 24 h. After the reaction is completed, centrifuge the product, wash it, and dry it to obtain expandable microspheres.

3. The lightweight and aging-resistant cable sheath material based on expandable microspheres according to claim 1, wherein: The dosage ratio of γ-aminopropyltriethoxysilane, ethanol aqueous solution and boron nitride in Step 1 is 9.6 g:50 mL:1 g.

4. The lightweight and aging-resistant cable sheath material based on expandable microspheres according to claim 3, wherein: The dosage ratio of pentaerythritol, toluene and phosphorus trichloride in Step 2 is 13.6 g:100 mL:29.2 g.

5. The lightweight and aging-resistant cable sheath material based on expandable microspheres according to claim 4, characterized in that: The dosage ratio of intermediate product 1, acetone, 2,4-dihydroxybenzophenone, sodium hydroxide and distilled water in Step 3 is 28.3 g:100 mL:21.5 g:3.9 g:20 mL.

6. The lightweight and anti-aging cable sheath material based on expandable microspheres according to claim 5, characterized in that: The dosage ratio of silane-modified boron nitride, N,N-dimethylformamide, intermediate product 2 and triethylamine in Step 4 is 1 g:100 mL:8.6 g:4.2 g.

7. The preparation method of a lightweight and aging-resistant cable sheath material based on expandable microspheres according to any one of claims 1-6, characterized in that: It comprises the following steps: Add ethylene propylene diene monomer rubber and chlorinated polyethylene into an open mill. After the first mixing, add expandable microspheres, processing aids, zinc oxide, vulcanizing agent and co-crosslinking agent, and then carry out the second mixing. After the mixing is completed, vulcanize to obtain a lightweight anti-aging cable sheath material based on expandable microspheres.

8. The preparation method of a lightweight and aging-resistant cable sheath material based on expandable microspheres according to claim 7, characterized in that: The vulcanizing agent is dicumyl peroxide; the co-crosslinking agent is one of triallyl cyanurate and triallyl isocyanurate; the processing aid is one of zinc stearate, white paraffin wax, stearic acid and polyethylene wax.

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