High-hydrophobicity self-cleaning insulating corrosion-resistant cable sheath material as well as preparation method and application thereof

Abstract

The invention provides a high-hydrophobicity self-cleaning insulating corrosion-resistant cable sheath material as well as a preparation method and application thereof. The sheath material is mainly composed of EVA resin, PVDF modified hollow glass beads, glass fibers, an antioxidant, a lubricant and a light stabilizer. The PVDF resin is combined with the hollow glass beads, and the PVDF resin is driven to migrate to the surface of the material by utilizing the floating characteristic of the hollow glass beads in the processing process, so that the hydrophobicity, the self-cleaning property, the corrosion resistance and the insulating property of the cable sheath material are remarkably improved. Experimental results show that the tensile strength and the elongation at break of the sheath material are both at a relatively high level, the water contact angle is greater than 130 degrees, the volume resistivity exceeds 2.0 * 10 < 13 > omega.m, and the sheath material has excellent brine resistance and acid and alkali corrosion resistance and can meet strict requirements in the ocean engineering fields such as oil drilling platforms, offshore wind power plants and submarine communication cables.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer cable materials, and specifically relates to a highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheathing material, and a preparation method and application thereof, which can significantly enhance the performance of the cable sheathing material in terms of self-cleaning, corrosion resistance and insulation. Background Art

[0002] Cables in marine engineering applications, such as oil drilling platforms, offshore wind farms, and submarine communications cables, face extremely harsh operating environments. These cables are constantly exposed to high humidity, high salt spray, and highly corrosive seawater, often also to intense ultraviolet radiation from the ocean surface. These conditions present significant challenges for cable materials, requiring them to possess a range of exceptional properties. Firstly, strong resistance to salt spray and seawater erosion is essential to protect against the constant attack of salt and seawater chemistry, preventing structural damage and performance degradation caused by corrosion. Secondly, resistance to UV aging is crucial, preventing aging, cracking, and performance degradation from prolonged UV exposure, thereby ensuring the cable's service life. Furthermore, a certain degree of self-cleaning capability can reduce the adhesion of marine organisms to the cable surface, reducing the additional burden and maintenance costs associated with biofouling. Furthermore, in such complex environments, the cable's insulation must be stable and reliable to ensure the safe and effective transmission of power and signals, safeguarding the smooth operation of marine engineering projects.

[0003] Traditional EVA cable sheaths are widely used for their flexibility and processing advantages, but they have the defect of inherent hydrophilicity (contact angle less than 90°), which makes them easily absorb moisture and pollutants, leading to deterioration of insulation performance. At the same time, their chemical corrosion resistance is poor, and they are prone to swelling failure in high-salt, strong acid and alkali environments, causing a decrease in insulation performance. Current modification technologies mostly use filler blending or filler surface modification to improve corrosion resistance and insulation performance, but these methods still have key problems such as limited improvement in hydrophobicity, insufficient stability against detergents, and difficulty in balancing flexibility and strength. It is difficult to meet the stringent requirements of marine engineering fields such as ships for long-term hydrophobicity, self-cleaning and strong chemical corrosion resistance of sheath materials.

[0004] PVDF resin has many advantages in cable material applications, such as strong chemical resistance, resistance to most acids, bases, salts, and organic solvents; good high-temperature resistance, and the ability to maintain stable performance in high-temperature environments; excellent electrical insulation properties, making it an ideal electrical insulation material; and outstanding mechanical properties, high strength, and resistance to wear and impact. However, it also has disadvantages such as high cost, resulting in high prices, brittleness and easy fracture, difficulty in processing, high melting point, and poor fluidity. The preparation of cable sheathing materials by blending PVDF with EVA has improved chemical resistance, high-temperature resistance, electrical insulation, and mechanical properties to a certain extent. However, the direct blending of PVDF with EVA results in a low PVDF concentration in the surface layer of the modified material, resulting in increased hydrophilicity of the material, which is not conducive to self-cleaning. At the same time, the improvement in corrosion resistance is not significant, making it difficult to fully utilize the advantages of PVDF to meet the stringent requirements of cable sheathing performance in special environments.

[0005] The present invention aims to provide a highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheathing material to solve the problems of low surface PVDF concentration, strong hydrophilicity, poor self-cleaning and insignificant improvement in corrosion resistance caused by direct blending of PVDF and EVA in the prior art. The specific method is to first use an isocyanate-based coupling agent to react with a hydroxylated PVDF resin to form a layer of coupling agent on the PVDF surface; then use the alkoxy group in the silane coupling agent to modify the hollow glass microspheres, thereby achieving PVDF loading on the hollow glass microspheres. During the extrusion process, the hollow glass microspheres tend to float upward and move to the surface, driving the PVDF resin to migrate to the surface of the material, so that the PVDF resin is mainly distributed on the surface of the product. The PVDF resin concentration of the surface layer of the prepared cable product is higher than that of the inner layer, thereby significantly improving the hydrophobicity of the cable, and enhancing the self-cleaning, corrosion resistance and insulation properties, better exerting the advantages of PVDF, and enabling it to meet the stringent requirements of cable sheath performance in special environments such as marine engineering. Summary of the Invention

[0006] The purpose of the present invention is to address the problems faced by current polyolefin cable sheath materials, such as poor self-cleaning performance, and unsatisfactory corrosion resistance and insulation. A highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material and its preparation method and application are provided to enhance the self-cleaning, corrosion resistance and insulation capabilities of polyolefin cable sheath materials, making them more in line with the application requirements of special environments such as marine engineering.

[0007] The present invention provides a highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material, comprising the following raw materials in parts by weight:

[0008] 60-100 parts of EVA resin, 10-20 parts of PVDF modified hollow glass microspheres, 10-20 parts of glass fiber, 0.5-1 part of antioxidant, 1-2 parts of lubricant, and 0.5-3 parts of light stabilizer.

[0009] The preparation method of the PVDF modified hollow glass microspheres comprises the following steps:

[0010] S1: placing PVDF resin in a sodium hydroxide solution for hydroxylation treatment, filtering, washing, and vacuum drying to obtain hydroxylated PVDF.

[0011] S2: Mixing hydroxylated PVDF and an isocyanate coupling agent in proportion in an internal mixer to prepare a PVDF-silane coupling agent; then continuing to stir and mix the PVDF-silane coupling agent, DMF, and hollow glass microspheres, and removing DMF in vacuo to obtain PVDF-modified hollow glass microspheres.

[0012] Preferably, the concentration of the sodium hydroxide solution in step S1 is 5-10 mol / L, the hydroxylation treatment temperature is 40-80° C., and the treatment time is 1-5 h.

[0013] Preferably, the hollow glass microspheres have a D50 particle size of 10-100 μm and a density of 0.1-0.6 g / cm 3 ; Further preferably, the average particle size is 40-65 μm, and the density is preferably 0.15-0.46 g / cm 3 .

[0014] Preferably, the banburying temperature in step S2 is 70-100° C., the banburying time is 30-60 min, and the rotation speed is 50-200 rpm; the isocyanate coupling agent is 1-20 wt % of the mass of the hydroxylated PVDF, and the isocyanate coupling agent is at least one of isocyanatepropyltriethoxysilane and isocyanatepropyltrimethoxysilane.

[0015] Preferably, the temperature for continuing stirring and mixing in step S2 is 50-80° C. and the time is 1-5 hours; and the mass ratio of the PVDF, DMF and hollow glass microspheres is 1:2-10:1-5.

[0016] Preferably, the EVA resin has a melt index of 1 to 10 g / 10 min at 190° C. and 2.16 kg; the content of vinyl acetate monomer is 10 to 30 wt %. More preferably, the melt index is 2 to 8 g / 10 min; the content of vinyl acetate monomer is 14 to 28 wt %.

[0017] Preferably, the glass fibers are chopped alkaline glass fibers having a length of 1-15 μm, preferably chopped alkaline glass fibers modified with a silane coupling agent.

[0018] Preferably, the antioxidant is at least one of a hindered phenol antioxidant, a phosphite antioxidant, and a thioester antioxidant. Preferably, the light stabilizer is at least one of a benzotriazole light stabilizer and a hindered amine light stabilizer. Preferably, the lubricant is one or more of ethylene bisstearamide, silicones, zinc stearate, calcium stearate, or pentaerythritol stearate.

[0019] The present invention also provides a method for preparing a highly hydrophobic and self-cleaning cable sheath material, comprising the following steps:

[0020] The components are mixed evenly in proportion, melt-extruded in a twin-screw extruder, granulated, and dried to obtain a highly hydrophobic and self-cleaning cable sheath material.

[0021] Preferably, the extrusion temperature of the twin-screw extruder is 160-200° C., the drying temperature is 70-100° C., and the drying time is 1-3 hours.

[0022] The present invention also includes a highly hydrophobic self-cleaning cable, comprising a conductor, a shielding layer, an insulating layer, an inner protective layer, a reinforcing layer and a sheath layer, wherein the sheath layer is prepared from the highly hydrophobic self-cleaning cable sheath material of the present invention.

[0023] Preferably, the present invention also provides the application of the above-mentioned highly hydrophobic self-cleaning cable in oil drilling platforms, offshore wind power generation, and submarine communication cables.

[0024] The PVDF-modified hollow glass microspheres of the present invention utilize PVDF resin (polyvinylidene fluoride) to provide excellent hydrophobicity, self-cleaning, corrosion resistance, and insulation properties. First, the PVDF resin is hydroxylated with sodium hydroxide to impart hydroxyl groups to its surface. Subsequently, an isocyanate-based coupling agent is introduced, where the isocyanate reacts with the hydroxyl groups, thereby depositing a layer of the coupling agent on the PVDF surface. Furthermore, the hollow glass microspheres are modified using the alkoxy groups in the silane coupling agent, ultimately achieving PVDF loading on the hollow glass microspheres and producing PVDF-modified hollow glass microspheres with unique properties.

[0025] The present invention utilizes the low density of hollow glass microspheres (usually 0.1-0.6g / cm 3 ), which is much lower than the density of EVA polymer melt (0.91-0.98g / cm 3 ), during the extrusion process, the hollow glass microspheres tend to float upward and move to the surface, driving the PVDF resin to migrate to the surface of the material, so that the PVDF resin is mainly distributed on the surface of the product. As a result, the concentration of PVDF resin on the surface of the cable product is higher than that of the PVDF resin in the inner layer, achieving high hydrophobicity of the cable product and improving self-cleaning, corrosion resistance and insulation performance.

[0026] The average particle size (D50 particle size) and density of the hollow glass microspheres are significantly affected by the surface PVDF resin concentration. The average particle size of the hollow glass microspheres is in the range of 10-300 μm, and the wall thickness is in the range of 1-5 microns. The microspheres with smaller particle sizes are subject to relatively small melt buoyancy and migrate more slowly; the microspheres with larger particle sizes are subject to greater melt buoyancy and are more likely to migrate to the surface quickly. Microspheres with larger particle sizes are more likely to break during the extrusion or injection molding process. The present invention preferably has an average particle size of 10-100 μm and a density of 0.1-0.6 g / cm 3 The hollow glass microspheres preferably have an average particle size of 40-65 μm, such as 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 45 μm, 55 μm, and 65 μm, and a density of 0.15-0.46 g / cm 3 , for example 0.15g / cm 3 , 0.2g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3 While ensuring that the processing process is not broken, it is conducive to the migration of hollow glass microspheres to the surface, driving the PVDF resin to enrich the surface of the material product, further improving the hydrophobicity of the product and its self-cleaning, corrosion resistance and insulation properties.

[0027] The present invention uses EVA resin as a base material, leveraging its polar molecular structure for good compatibility with glass fiber fillers and the flexibility imparted by its low crystallinity. When the EVA resin has a high melt flow rate (MFR), the melt has better fluidity and can flow more rapidly during extrusion, making it easier for the hollow glass microspheres to migrate within the resin melt to the material surface. Furthermore, the highly fluid resin melt can, to a certain extent, reduce the constraints on the hollow glass microspheres, allowing them to float to the surface more easily. If the EVA resin has a low MFR, the melt is more viscous and flows more slowly. In this case, the migration of the hollow glass microspheres within the resin melt encounters significant resistance, making it more difficult for them to quickly migrate to the material surface. Furthermore, they may be partially or completely covered by the resin melt. An EVA resin with a melt index of 1 to 10 g / 10 min at 190°C and 2.16 kg facilitates the migration of the hollow glass microspheres to the material surface. The embodiments further prefer an EVA resin with a melt index of 2 to 8 g / 10 min.

[0028] The advantages or beneficial effects of the highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material and the cable prepared therefrom of the present invention include at least:

[0029] The highly hydrophobic, self-cleaning, insulating, and corrosion-resistant cable sheathing material prepared by this invention is constructed by loading PVDF onto hollow glass microspheres. During the extrusion process, the hollow glass microspheres easily float to the material surface, driving the PVDF resin to migrate with them, resulting in the PVDF resin being primarily distributed on the surface of the finished product. The resulting cable product has a higher PVDF resin concentration on the surface than in the inner layer, significantly improving the cable's hydrophobicity, self-cleaning, corrosion resistance, and insulation properties. Furthermore, by selecting the appropriate average particle size of the hollow glass microspheres and the melt flow rate of the EVA resin, these properties are further optimized to meet the stringent requirements of cable applications in marine environments and other applications. DETAILED DESCRIPTION

[0030] To more clearly illustrate the objectives, technical solutions, and advantages of the present invention, the technical solutions of the present invention will be described in detail below through specific embodiments. It should be noted that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. The actual scope of protection of the present invention shall be based on the definition of the claims.

[0031] Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available. The amounts of the components in the following examples are 1 g per part by weight unless otherwise specified.

[0032] The EVA resin and hollow glass microspheres used in the examples and comparative examples are as follows:

[0033] EVA-1: Beijing Organic, EVA14-2, VA content is 14wt%, melt index is 2.0g / 10min (190℃, 2.16kg).

[0034] EVA-2: Mitsui Chemicals V 421, Japan, VA content of 28 wt%, melt index of 4.0 g / 10 min (190° C., 2.16 kg).

[0035] EVA-3: Hanwha EVA1826, VA content is 26wt%, melt index is 4.5g / 10min (190℃, 2.16kg).

[0036] EVA-4: 450, VA content of 18wt%, melt index of 8g / 10min (190℃, 2.16kg), purchased from DuPont, USA.

[0037] EVA-5: EVA 670, VA content of 12 wt%, melt index of 0.35 g / 10 min (190° C., 2.16 kg), purchased from ExxonMobil.

[0038] Hollow glass microspheres-1: H15, Zhongke Yali; D50 particle size is 55μm, true density is 0.15g / cm 3 , the wall thickness is 1 to 3 μm.

[0039] Hollow glass microsphere-2: K20, 3M Company, USA; D50 particle size is 65μm, true density is 0.2g / cm 3 , the wall thickness is 1 to 3 μm.

[0040] Hollow glass microsphere-3: H32HS, Zhongke Yali; D50 particle size is 42μm, true density is 0.32g / cm 3 , the wall thickness is 1 to 3 μm.

[0041] Hollow glass microsphere-4: H46HS, Zhongke Yali; D50 particle size is 24μm, true density is 0.46g / cm 3 , the wall thickness is 1 to 3 μm.

[0042] Hollow glass microsphere-5: H50HS, Zhongke Yali; D50 particle size is 37μm, true density is 0.50g / cm 3 , the wall thickness is 1 to 3 μm.

[0043] Hollow glass microsphere-6: IM30K, 3M Company, USA; D50 particle size is 16μm, true density is 0.6g / cm 3 , the wall thickness is 1 to 3 μm.

[0044] Glass fiber: KH507 modified chopped glass fiber with an average diameter of 10-15μm.

[0045] Antioxidant: a mixture of antioxidant 1076 and antioxidant 168 in a ratio of 1:1.

[0046] Lubricant: Ethylene bisstearamide.

[0047] Light stabilizer: Light stabilizer 944.

[0048] 1. Preparation of highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheathing materials.

[0049] 1. The preparation method of PVDF modified hollow glass microspheres includes the following steps:

[0050] S1: PVDF resin was placed in 7 mol / L sodium hydroxide solution, stirred at 50°C for 3 h, filtered, washed with deionized water, and vacuum dried at 80°C for 5 h to obtain hydroxylated PVDF.

[0051] S2: According to the material ratio in Table 1, hydroxylated PVDF and isocyanatepropyltriethoxysilane were mixed in proportion in an internal mixer at 70°C for 40 minutes to prepare a PVDF-silane coupling agent; then, the PVDF-silane coupling agent, DMF, and hollow glass microspheres were stirred and mixed at 60°C for 3 hours, and the DMF was removed in vacuo to prepare PVDF-modified hollow glass microspheres.

[0052] Table 1: The weight parts of each raw material of PVDF modified hollow glass microspheres are as follows.

[0053]

[0054] 9# modified hollow glass microspheres: omit isocyanatepropyltriethoxysilane, and other conditions are the same as 2# modified hollow glass microspheres.

[0055] 10# modified hollow glass microspheres: step S1 was omitted, and PVDF was used instead of hydroxylated PVDF. Other conditions were the same as those of 2# modified hollow glass microspheres.

[0056] 11# modified hollow glass microspheres: vinyl triethoxysilane is used instead of isocyanate propyl triethoxysilane, and other conditions are the same as 2# modified hollow glass microspheres.

[0057] 2. The present invention relates to a method for preparing a highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material, which specifically comprises the following steps:

[0058] The materials in Table 2 or Table 3 are stirred and mixed according to the weight ratio to obtain a mixed material; the obtained mixed material is added to a twin-screw extruder for extrusion granulation, the temperature of the twin-screw extruder is 160-200°C, the drying temperature is 80°C, and the drying time is 1h to obtain the cable sheath material.

[0059] Table 2: The mass parts (g) of each component in Examples 1-10 are as follows.

[0060]

[0061]

[0062] Table 3: The mass parts (g) of each component in Comparative Examples 1-6 are as follows.

[0063]

[0064] Comparative Example 7: According to the raw material ratio of Example 2, without pre-modifying the hollow glass microspheres with PVDF, EVA, PVDF, isocyanatepropyltriethoxysilane, hollow glass microspheres, glass fiber, antioxidant, lubricant, and light stabilizer were directly mixed and melt-extruded to prepare a sheath material.

[0065] 3. Performance evaluation:

[0066] The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath materials prepared in the examples and comparative examples were subjected to relevant performance tests. The specific test methods are as follows:

[0067] (1) Evaluation of salt water resistance

[0068] A sodium chloride solution with a mass concentration of 5% was prepared, and the cable sheath materials of the embodiment and the comparative example were immersed in the sodium chloride and placed in an oven at 100°C for 96 hours. The change rate of tensile strength and the change rate of elongation at break were then tested, and the test results were taken as the average value of 5 tests.

[0069] (2) Acid / alkali resistance evaluation

[0070] Acid / alkali resistance was evaluated according to EN 50306. For acid resistance, samples of the jacket layers according to the Examples and Comparative Examples were immersed in a 1 mol / L aqueous oxalic acid solution at room temperature for 168 hours. The elongation at break and tensile strength were then measured, and the changes in the tensile strength and elongation at break were calculated. Each test was repeated five times, and the average value was calculated.

[0071] Alkali resistance: After the jacket layer samples according to the embodiments and comparative examples were immersed in a 1 mol / L sodium hydroxide aqueous solution at room temperature for 168 hours, the elongation at break and the change rate of tensile strength were measured. Each group was tested 5 times and the average value was calculated.

[0072] (3) Surface hydrophobicity

[0073] According to the method specified in GB / T 30447-2013 "Nanofilm Contact Angle Measurement Method", the surface water contact angle of the sample was tested to determine the antifouling ability of the sample.

[0074] (4) Insulation performance test

[0075] The experimental samples were subjected to volume resistance tests in accordance with GB / T 1410-2016 before and after salt water, acid and alkali treatment to evaluate insulation performance.

[0076] (5) Calculation method of rate of change

[0077] Tensile Strength Test: The tensile strength of cable sheath materials was tested using ISO 527-2012, "Test Methods for Tensile Properties of Plastics." Tensile Strength Change = (Tensile Strength Before Immersion - Tensile Strength After Immersion) / Tensile Strength Before Immersion × 100%.

[0078] Elongation at break: Tested in accordance with ISO 527-1-2019. Test conditions: 23°C. Change in elongation at break = (elongation at break before immersion - elongation at break after immersion) / elongation at break before immersion × 100%.

[0079] Table 4: Performance test of cable sheath material in the embodiment

[0080]

[0081]

[0082] According to the test results in Table 4, the highly hydrophobic, self-cleaning, insulated, and corrosion-resistant cable sheathing material prepared by the present invention exhibits excellent comprehensive performance, with both tensile strength and elongation at break at a high level, and excellent resistance to salt, acid, and alkali corrosion. In addition, the water contact angle of the material is greater than 130°, and the volume resistivity exceeds 2.0×10 1 3Ω·m, and has excellent self-cleaning, corrosion resistance, and insulation properties. These properties enable it to meet the stringent material requirements of marine engineering fields such as oil drilling platforms, offshore wind farms, and submarine communication cables.

[0083] By comparing Examples 2, 6-10, it can be found that the average particle size (D50 particle size) and density of the hollow glass microspheres have a significant effect on the concentration of the surface PVDF resin. In Examples 2, 6-7, the average particle size of the hollow glass microspheres used is 40-65 μm, and the density is 0.15-0.4 g / cm 3 During processing, hollow glass microspheres within this particle size range are not easily broken and can migrate smoothly to the surface of the material within this density, thereby driving the PVDF resin to accumulate on the surface of the material product. This process significantly improves the hydrophobicity of the product, while further enhancing its self-cleaning, corrosion resistance, and insulation properties.

[0084] Table 5: Performance test of comparative cable sheath materials

[0085]

[0086]

[0087] By comparing Example 2 with Comparative Example 2, it can be found that the melt flow rate of EVA resin has a significant effect on material properties within a certain range. EVA resin with a high melt index can flow faster during the extrusion process, thereby more effectively driving the migration of hollow glass microspheres in the resin melt to the material surface, which is conducive to the enrichment of PVDF on the surface. The EVA resin melt index selected in Example 2 is 2 to 8 g / 10 min, while the EVA resin melt index selected in Comparative Example 2 is 0.35 g / 10 min. EVA resin with a high melt flow rate is more conducive to driving PVDF resin to enrich the surface of the material product, thereby significantly improving the hydrophobicity, self-cleaning, corrosion resistance and insulation properties of the product.

[0088] By comparing Example 2 with Comparative Examples 1 and 3-7, it can be found that Comparative Example 1 does not add PVDF-modified hollow glass microspheres, and Comparative Example 6 uses unmodified hollow glass microspheres. The surfaces of the prepared sheathing materials are free of PVDF resin. Although Comparative Examples 3-5 add PVDF and hollow glass microspheres, the two are not connected by an isocyanate coupling agent. During the extrusion process, the hollow glass microspheres cannot drive the PVDF to migrate to the material surface, resulting in a significant decrease in the hydrophobicity, self-cleaning, corrosion resistance, and insulation properties of the products. Comparative Example 7 does not pre-modify the hollow glass microspheres with PVDF. The insulation properties of the prepared sheathing materials are significantly reduced after salt corrosion and acid-base corrosion.

[0089] The above embodiments are merely examples provided to illustrate the present invention and are not intended to limit the possible implementations of the present invention. Based on the disclosure of the present invention, those skilled in the relevant art may make various modifications and adjustments. It is neither possible nor necessary to enumerate all possible implementations. Any modification, equivalent substitution, or improvement made within the basic principles and scope of the present invention shall be deemed to fall within the scope of protection of the present invention.

Claims

1. A highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material, characterized in that: The invention comprises the following raw materials in parts by weight: EVA resin 60-100 parts, PVDF modified hollow glass microspheres 10-20 parts, glass fiber 10-20 parts, antioxidant 0.5-1 parts, lubricant 1-2 parts, light stabilizer 0.5-3 parts; The preparation method of the PVDF modified hollow glass microspheres comprises the following steps: S1: placing PVDF resin in a sodium hydroxide solution for hydroxylation, filtering, washing, and vacuum drying to obtain hydroxylated PVDF; S2: Mixing hydroxylated PVDF and an isocyanate coupling agent in a proportion in an internal mixer to prepare a PVDF-silane coupling agent; then further stirring and mixing the PVDF-silane coupling agent, DMF, and hollow glass microspheres, and removing the DMF in vacuo to obtain PVDF-modified hollow glass microspheres; The EVA resin has a melt index of 1 to 10 g / 10 min at 190° C. and 2.16 kg; and the content of vinyl acetate monomer is 10 to 30 wt %.

2. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to claim 1, characterized in that: The EVA resin has a melt index of 2 to 8 g / 10 min at 190° C. and 2.16 kg; and the content of vinyl acetate monomer is 14 to 28 wt %.

3. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to claim 1, characterized in that: The glass fiber is a chopped alkaline glass fiber modified by a silane coupling agent, and the length of the chopped alkaline glass fiber is 1-15 μm; the average particle size of the hollow glass microspheres is 10-100 μm, and the density is 0.1-0.6 g / cm 3 .

4. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to claim 1, characterized in that: The average particle size of the hollow glass microspheres is 40-65 μm, and the density is 0.15-0.46 g / cm 3 .

5. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to any one of claims 1 to 4, characterized in that: In step S1, the concentration of the sodium hydroxide solution is 5-10 mol / L, the hydroxylation treatment temperature is 40-80° C., and the treatment time is 1-5 h.

6. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to any one of claims 1 to 4, characterized in that: The banburying temperature in step S2 is 70-100°C, the banburying time is 30-60 minutes, and the rotation speed is 50-200 rpm; the isocyanate coupling agent is 1-20 wt% of the mass of the hydroxylated PVDF; the temperature for continued stirring and mixing in step S2 is 50-80°C and the time is 1-5 hours; the mass ratio of the PVDF, DMF, and hollow glass microspheres is 1:2-10:1-5.

7. The highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheath material according to any one of claims 1 to 4, characterized in that: The antioxidant is at least one of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants; the light stabilizer is at least one of benzotriazole light stabilizers and hindered amine light stabilizers; and the lubricant is one or more combinations of ethylene bisstearamide, silicones, zinc stearate, calcium stearate or pentaerythritol stearate.

8. A method for preparing a highly hydrophobic, self-cleaning, insulating, and corrosion-resistant cable sheathing material according to any one of claims 1 to 7, characterized in that: The following steps are involved: The components are mixed evenly in proportion, melt-extruded in a twin-screw extruder, granulated, and dried to obtain a highly hydrophobic and self-cleaning cable sheath material.

9. An application of the highly hydrophobic and self-cleaning insulating and corrosion-resistant cable sheathing material according to any one of claims 1 to 7, characterized in that: Applications in oil drilling platforms, offshore wind power generation, and submarine communication cables.

10. A highly hydrophobic and self-cleaning insulated and corrosion-resistant cable, comprising a conductor, a shielding layer, an insulating layer, an inner protective layer, a reinforcement layer and a sheath layer, wherein the sheath layer is made of the highly hydrophobic and self-cleaning cable sheath material according to any one of claims 1 to 7.

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