Cable interface bonding modification material and its preparation method

Abstract

This invention discloses a cable interface bonding modifier and its preparation method. The cable interface bonding modifier comprises, by mass percentage: 50-60% matrix resin, 15-20% modifier, and 25-30% conductive filler. The matrix resin is composed of polypropylene and an elastomer, with a mass ratio of polypropylene to elastomer of (2.2-2.8):1. The modifier is a hyperbranched polyester multifunctional modifier with a molecular weight of 9000-11000 and a polar group density of 2.5-3.5 mmol / g. This invention improves the stability of the interface bonding between the semiconductive shielding layer and the insulation layer of a cable.

Description

Technical Field

[0001] This invention relates to the field of cable material technology, and in particular to a cable interface bonding modified material and its preparation method. Background Technology

[0002] High-voltage direct current (HVDC) cables are important carriers of energy transmission. Their structure mainly includes a conductor, an inner semiconductive shielding layer, an insulation layer, and an outer semiconductive shielding layer. Among them, the insulation layer is the core component of the cable, serving as an electrical insulation layer; the semiconductive shielding layer is located between the conductor and the insulation layer, mainly used to uniformly distribute the electric field on the conductor surface, regulate the electric field transition between the conductor and the insulation layer, and prevent the accumulation of space charge in the insulation layer.

[0003] Currently, the semiconductive shielding layer in cables is typically made of polymer composite materials with added conductive fillers. The introduction of conductive fillers gives the semiconductive shielding layer strong polarity, while the insulation layer mainly uses non-polar polyolefin materials. Due to the significant differences in molecular structure and polarity between the two materials, their interfacial compatibility is poor, and microscopic defects easily form at the interface, leading to unstable interfacial bonding between the semiconductive shielding layer and the insulation layer. Especially during cable operation, the Joule heating generated by the conductor causes thermal expansion and contraction of the materials. This temperature cycling further exacerbates the problem of unstable interfacial bonding, affecting the operational reliability of the cable. Summary of the Invention

[0004] The main objective of this invention is to solve the technical problem of unstable bonding between the semiconductive shielding layer and the insulation layer in existing cables.

[0005] The first aspect of this invention provides a cable interface bonding modifier, wherein the cable interface bonding modifier comprises, by mass percentage: 50-60% matrix resin, 15-20% modifier, and 25-30% conductive filler; wherein the matrix resin is composed of polypropylene and elastomer, and the mass ratio of polypropylene to elastomer is (2.2-2.8):1; the modifier is a hyperbranched polyester multifunctional modifier, the molecular weight of the hyperbranched polyester multifunctional modifier is 9000-11000, and the density of polar groups in the hyperbranched polyester multifunctional modifier is 2.5-3.5 mmol / g.

[0006] Optionally, the elastomer is a styrene-ethylene-butene-styrene block copolymer, wherein the styrene content in the styrene-ethylene-butene-styrene block copolymer is 28-32 wt%, and the melt index of the styrene-ethylene-butene-styrene block copolymer is 3.5-4.5 g / 10 min; the polypropylene is isotactic polypropylene with an isotacticity greater than 95%, and the melt index of the isotactic polypropylene is 1.5-2.5 g / 10 min.

[0007] Optionally, the conductive filler is carbon nanoparticles with a particle size of 25-45 nm and a specific surface area of ​​600-900 m² / g; the surface of the carbon nanoparticles is carboxylated, with a carboxyl content of 2.5-3.5 mmol / g and the surface of the carbon nanoparticles also containing 0.8-1.2 mmol / g of hydroxyl groups.

[0008] Optionally, the cable interface bonding modification material further includes 1.5-2.5 wt% of a silane-epoxy bifunctional coupling agent, wherein the silane-epoxy bifunctional coupling agent comprises silane groups and epoxy groups, and the molar ratio of the silane groups to the epoxy groups is 1:(1.3-1.4).

[0009] Optionally, the hyperbranched polyester multifunctional modifier has 12-15 terminal hydroxyl groups, the hydroxyl value of the hyperbranched polyester multifunctional modifier is 95-115 mgKOH / g, and the degree of branching of the hyperbranched polyester multifunctional modifier is 0.38-0.42; 55-65% of the terminal hydroxyl groups undergo esterification with maleic anhydride to form ester groups, and 80-90% of the remaining unreacted terminal hydroxyl groups undergo ring-opening reaction with the epoxy groups in the silane-epoxy bifunctional coupling agent.

[0010] Optionally, the cable interface bonding modification material further includes 0.3-0.8 wt% of an antioxidant, which includes a hindered phenolic antioxidant and a sulfur-based synergist, wherein the mass ratio of the hindered phenolic antioxidant to the sulfur-based synergist is (1.4-1.6):1; the hindered phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the sulfur-based synergist is octadecyl thiodipropionate.

[0011] A second aspect of the present invention provides a method for preparing a cable interface bonding modified material, comprising the following steps:

[0012] The first step is to weigh 100 parts of raw materials, including 18-22 parts of elastomer, 15-20 parts of hyperbranched polyester multifunctional modifier, 45-53 parts of polypropylene, 25-30 parts of carbon nanoparticles, 1.5-2.5 parts of silane-epoxy bifunctional coupling agent, and 0.3-0.8 parts of antioxidant.

[0013] The second step involves adding the carbon nanoparticles to xylene at a mass ratio of 1:(4-5) and ultrasonically dispersing for 30-40 minutes to obtain a carbon nanoparticle dispersion.

[0014] The third step is to dissolve the elastomer in the carbon nanoparticle dispersion and stir it at 80-90°C to obtain an elastomer solution.

[0015] Fourth step: Mix the hyperbranched polyester multifunctional modifier with maleic anhydride at a molar ratio of 1:(0.6-0.7), add it to the elastomer solution, heat to 115-125℃, and stir for 1-2 hours; add the polypropylene and continue stirring for 0.5-1 hour.

[0016] Fifth step: Cool down to 90-100℃, dissolve the silane-epoxy bifunctional coupling agent in isopropanol, control the mass fraction to be 3-5%, and slowly add it to the mixture obtained in the fourth step;

[0017] The sixth step involves removing the solvent by vacuum distillation at a temperature of 85-95℃ to obtain the primary product.

[0018] Step 7: The primary product is melt-blended in a co-rotating twin-screw extruder at an extrusion temperature of 165-175℃ and a screw speed of 300-500 r / min.

[0019] Step 8: Vacuum dry the extruded product at 70-80℃ for 4-6 hours to obtain the cable interface bonding modified material.

[0020] Optionally, in the fifth step, the temperature of the mixture obtained in the fourth step is controlled to be 85-90℃; the addition rate of the silane-epoxy bifunctional coupling agent solution is 2-4 ml / min; after the addition is completed, the temperature is increased to 95-100℃ at a rate of 2-3℃ / min, and the reaction is maintained at this temperature for 0.5-1h.

[0021] Optionally, before the sixth step, an antioxidant is added to the product after the reaction in the fifth step, wherein the amount of antioxidant added is 0.3-0.8 wt% of the total mass of the product; the antioxidant is composed of a hindered phenolic antioxidant and a sulfur-based synergist, wherein the mass ratio of the hindered phenolic antioxidant to the sulfur-based synergist is (1.4-1.6):1; the pressure of the vacuum distillation is 30-40 kPa, and the distillation time is 2-3 h.

[0022] This invention provides a cable interface bonding modified material. By introducing a specific proportion of elastomer (the mass ratio of polypropylene to elastomer is (2.2-2.8):1) into the matrix resin, the elastic deformation capability of the matrix material is improved, enhancing its adaptability to temperature cycling. Simultaneously, a hyperbranched polyester multifunctional modifier and conductive filler work synergistically. On the one hand, the polar groups in the modifier molecules form chemical bonds with the functional groups on the surface of the conductive filler; on the other hand, the terminal hydroxyl groups react with the matrix resin, forming a stable interface structure between the semiconductive shielding layer and the insulating layer, effectively improving the interfacial bonding stability between the two layers. Detailed Implementation

[0023] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0024] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0025] The raw materials used in the embodiments of this invention and their sources are as follows:

[0026] The elastomer was a commercially available styrene-ethylene-butene-styrene block copolymer (SEBS), purchased from Asahi Kasei Corporation, Japan, with a styrene content of 30 wt% and a melt index of 4.0 g / 10 min (230℃, 2.16 kg); the polypropylene (PP) was isotactic polypropylene with an isotacticity greater than 95%, purchased from China Petroleum & Chemical Corporation, with a melt index of 2.0 g / 10 min (230℃, 2.16 kg); the carbon nanoparticles were conductive carbon black with an average particle size of 35 nm, purchased from Immers, Germany. The specific surface area was 750 m² / g; the hyperbranched polyester multifunctional modifier was a hyperbranched polyester with a hydroxyl value of 105 mg KOH / g, purchased from Standard Company, USA, with a molecular weight of 10,000; the silane-epoxy bifunctional coupling agent was γ-glycidyl etheroxypropyltrimethoxysilane, purchased from Dow Corning, USA; the antioxidants were the hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and the sulfur-based synergist octadecyl thiodipropionate, both purchased from BASF, Germany.

[0027] Before preparing the materials for the examples, pretreatment of the raw materials is required. Polypropylene and SEBS were placed in a vacuum drying oven at 80±2℃ for 12 hours to remove moisture and volatile substances. Carbon nanoparticles were dried in a vacuum drying oven at 70±2℃ for 8 hours to improve their dispersibility. Other raw materials must be sealed and stored in a desiccator before use to prevent moisture absorption.

[0028] The main equipment used in the preparation process includes:

[0029] 1. Vacuum drying oven: Temperature control range 20-200℃, control accuracy ±1℃;

[0030] 2. Enclosed rotor mixer: operating temperature range 50-200℃, rotor speed 0-100rpm;

[0031] 3. Co-rotating twin-screw extruder: screw diameter 40mm, length-to-diameter ratio 40:1, temperature control range 50-300℃;

[0032] 4. Vacuum oven: Temperature control range 20-200℃, vacuum degree ≤133Pa.

[0033] Example 1

[0034] The cable interface bonding modification material is prepared according to the following steps:

[0035] First, weigh the following raw materials by weight percentage:

[0036] The matrix resin is 55% (of which the mass ratio of polypropylene to SEBS is 2.5:1), the hyperbranched polyester multifunctional modifier is 17%, the carbon nanoparticles are 27%, the silane-epoxy bifunctional coupling agent is 2.0%, and the antioxidant is 0.5% (of which the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0037] The second step involves adding carbon nanoparticles to xylene at a mass ratio of 1:4.5 and ultrasonically dispersing for 35 minutes to obtain a carbon nanoparticle dispersion.

[0038] The third step is to dissolve SEBS in the carbon nanoparticle dispersion and stir it at 85°C to obtain a uniform elastomer solution.

[0039] Fourth step: Mix the hyperbranched polyester multifunctional modifier with maleic anhydride at a molar ratio of 1:0.65, add it to the elastomer solution, heat to 120°C, and stir for 1.5 hours; add polypropylene and continue stirring for 0.8 hours.

[0040] Fifth step: Cool down to 95℃, dissolve the silane-epoxy bifunctional coupling agent in isopropanol, control the mass fraction to 4%, and slowly add it to the mixture obtained in the fourth step at a rate of 3 ml / min; after the addition is complete, raise the temperature to 98℃ at a rate of 2.5℃ / min and keep the reaction at this temperature for 0.8 h.

[0041] Step 6: Add antioxidants and remove solvent by vacuum distillation, controlling the temperature at 90℃, the pressure at 35kPa, and the distillation time at 2.5h.

[0042] Step 7: The obtained product is melt-blended in a co-rotating twin-screw extruder at an extrusion temperature of 170°C and a screw speed of 400 r / min.

[0043] Step 8: The extruded product is vacuum dried at 75°C for 5 hours to obtain the cable interface bonding modified material.

[0044] Example 2

[0045] The cable interface bonding modification material is prepared according to the following steps:

[0046] The first step is to weigh the following raw materials by mass percentage: 52% matrix resin (where the mass ratio of polypropylene to SEBS is 2.3:1), 19% hyperbranched polyester multifunctional modifier, 28% carbon nanoparticles, 1.8% silane-epoxy bifunctional coupling agent, and 0.6% antioxidant (where the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0047] The second step involves adding carbon nanoparticles to xylene at a mass ratio of 1:4.5 and ultrasonically dispersing for 35 minutes to obtain a carbon nanoparticle dispersion.

[0048] The third step is to dissolve SEBS in the carbon nanoparticle dispersion and stir it at 85°C to obtain a uniform elastomer solution.

[0049] Fourth step: Mix the hyperbranched polyester multifunctional modifier with maleic anhydride at a molar ratio of 1:0.65, add it to the elastomer solution, heat to 120°C, and stir for 1.5 hours; add polypropylene and continue stirring for 0.8 hours.

[0050] Fifth step: Cool down to 95℃, dissolve the silane-epoxy bifunctional coupling agent in isopropanol, control the mass fraction to 4%, and slowly add it to the mixture obtained in the fourth step at a rate of 3 ml / min; after the addition is complete, raise the temperature to 98℃ at a rate of 2.5℃ / min and keep the reaction at this temperature for 0.8 h.

[0051] Step 6: Add antioxidants and remove solvent by vacuum distillation, controlling the temperature at 90℃, the pressure at 35kPa, and the distillation time at 2.5h.

[0052] Step 7: The obtained product is melt-blended in a co-rotating twin-screw extruder at an extrusion temperature of 170°C and a screw speed of 400 r / min.

[0053] Step 8: The extruded product is vacuum dried at 75°C for 5 hours to obtain the cable interface bonding modified material.

[0054] Example 3

[0055] The cable interface bonding modification material is prepared according to the following steps:

[0056] The first step is to weigh the following raw materials by mass percentage: 58% matrix resin (where the mass ratio of polypropylene to SEBS is 2.7:1), 15% hyperbranched polyester multifunctional modifier, 25% carbon nanoparticles, 2.2% silane-epoxy bifunctional coupling agent, and 0.4% antioxidant (where the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0057] The second step involves adding carbon nanoparticles to xylene at a mass ratio of 1:4.5 and ultrasonically dispersing for 35 minutes to obtain a carbon nanoparticle dispersion.

[0058] The third step is to dissolve SEBS in the carbon nanoparticle dispersion and stir it at 85°C to obtain a uniform elastomer solution.

[0059] Fourth step: Mix the hyperbranched polyester multifunctional modifier with maleic anhydride at a molar ratio of 1:0.65, add it to the elastomer solution, heat to 120°C, and stir for 1.5 hours; add polypropylene and continue stirring for 0.8 hours.

[0060] Fifth step: Cool down to 95℃, dissolve the silane-epoxy bifunctional coupling agent in isopropanol, control the mass fraction to 4%, and slowly add it to the mixture obtained in the fourth step at a rate of 3 ml / min; after the addition is complete, raise the temperature to 98℃ at a rate of 2.5℃ / min and keep the reaction at this temperature for 0.8 h.

[0061] Step 6: Add antioxidants and remove solvent by vacuum distillation, controlling the temperature at 90℃, the pressure at 35kPa, and the distillation time at 2.5h.

[0062] Step 7: The obtained product is melt-blended in a co-rotating twin-screw extruder at an extrusion temperature of 170°C and a screw speed of 400 r / min.

[0063] Step 8: The extruded product is vacuum dried at 75°C for 5 hours to obtain the cable interface bonding modified material.

[0064] Comparative Example 1

[0065] To verify the superior performance of the modified material of the present invention, Comparative Example 1 was designed. Its preparation steps were the same as in Example 1, but without the addition of hyperbranched polyester multifunctional modifiers. The specific formulation is as follows:

[0066] The first step is to weigh the following raw materials by mass percentage: 72% matrix resin (where the mass ratio of polypropylene to SEBS is 2.5:1), 27% carbon nanoparticles, 2.0% silane-epoxy bifunctional coupling agent, and 0.5% antioxidant (where the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0067] The subsequent preparation steps are the same as in Example 1.

[0068] Comparative Example 2

[0069] Comparative Example 2 without SEBS, the specific formulation is as follows:

[0070] The first step is to weigh the following raw materials by mass percentage: 55% polypropylene, 17% hyperbranched polyester multifunctional modifier, 27% carbon nanoparticles, 2.0% silane-epoxy bifunctional coupling agent, and 0.5% antioxidant (where the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0071] The subsequent preparation steps are the same as in Example 1.

[0072] Comparative Example 3

[0073] Comparative Example 3 does not contain a silane-epoxy bifunctional coupling agent. The specific formulation is as follows:

[0074] The first step is to weigh the following raw materials by mass percentage: 57% matrix resin (where the mass ratio of polypropylene to SEBS is 2.5:1), 17% hyperbranched polyester multifunctional modifier, 25% carbon nanoparticles, and 0.5% antioxidant (where the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is 1.5:1).

[0075] The subsequent preparation steps are the same as in Example 1, but step 5 is omitted.

[0076] Performance testing

[0077] 1. Interface bonding strength test

[0078] (1) Sample preparation: The modified material and polyethylene insulating material (density 0.92 g / cm³, melt index 2.0 g / 10 min) were hot-pressed at 180℃ and 5 MPa to form a three-layer structure sample with the following structure: modified material (0.5 mm) / insulating material (1.0 mm) / modified material (0.5 mm).

[0079] (2) Test conditions: room temperature (23℃), tensile rate 50mm / min;

[0080] (3) Take 5 parallel samples for testing and take the average value.

[0081] 2. Temperature cycling performance test

[0082] (1) Temperature cycling conditions: cycling from 23℃ to 90℃, each cycle lasting 12 hours, for a total of 100 cycles;

[0083] (2) After the cycle, test according to the above interface combined with the strength test method;

[0084] (3) Strength retention rate = strength after cycling / initial strength × 100%.

[0085] 3. Volume resistivity test

[0086] (1) Sample preparation: The material is prepared into a circular sample with a thickness of 2 mm;

[0087] (2) Test conditions: The four-probe method was used to test at 23℃ and 90℃ respectively;

[0088] (3) Test each temperature point 3 times and take the average value.

[0089] 4. Microscopic morphology analysis

[0090] (1) The material is fractured in liquid nitrogen to obtain the fracture surface;

[0091] (2) The cross-sectional morphology was observed using a scanning electron microscope with an accelerating voltage of 15 kV;

[0092] (3) Focus on analyzing the interface bonding and the dispersion state of the conductive filler.

[0093] Test Results

[0094] Table 1 Performance test results of each embodiment and comparative example

[0095] Sample number Interfacial bond strength (MPa) Strength retention rate after temperature cycling (%) Volume resistivity at 23℃ (Ω·cm) Volume resistivity at 90℃ (Ω·cm) Example 1 3.2 92 75 280 Example 2 3.5 90 82 295 Example 3 3.0 88 68 265 Comparative Example 1 1.8 65 95 340 Comparative Example 2 1.5 55 88 325 Comparative Example 3 2.0 70 85 315

[0096] The test results show that:

[0097] 1. Interfacial bonding performance: The interfacial bonding strength of Examples 1-3 all exceeded 3.0 MPa, which is significantly better than that of Comparative Examples 1-3 (all below 2.0 MPa). This indicates that the ternary composite system provided by the present invention can effectively improve the interfacial bonding performance of materials.

[0098] 2. Temperature cycling performance: The strength retention rate of Examples 1-3 after 100 temperature cycles is all above 88%, while the strength retention rate of Comparative Examples 1-3 is all below 70%. This indicates that the material system of the present invention has excellent interfacial bonding stability.

[0099] 3. Electrical conductivity: The volume resistivity of all samples at 23℃ and 90℃ met the requirements for practical use. However, the resistivity increase of Examples 1-3 at high temperatures was relatively small, indicating that their conductive network structure was more stable. This is attributed to the introduction of modifiers that improved the dispersion state of the conductive filler.

[0100] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cable interface bonding modified material, characterized in that, By weight percentage, the cable interface bonding modifier comprises: 50-60% matrix resin, 15-20% modifier, and 25-30% conductive filler; wherein the matrix resin is composed of polypropylene and elastomer, and the mass ratio of polypropylene to elastomer is (2.2-2.8):1; the modifier is a hyperbranched polyester multifunctional modifier, the molecular weight of the hyperbranched polyester multifunctional modifier is 9000-11000, and the density of polar groups in the hyperbranched polyester multifunctional modifier is 2.5-3.5 mmol / g; The elastomer is a styrene-ethylene-butene-styrene block copolymer, wherein the styrene content in the styrene-ethylene-butene-styrene block copolymer is 28-32 wt%, and the melt index of the styrene-ethylene-butene-styrene block copolymer is 3.5-4.5 g / 10 min; the polypropylene is isotactic polypropylene with an isotacticity greater than 95%, and the melt index of the isotactic polypropylene is 1.5-2.5 g / 10 min. The conductive filler is carbon nanoparticles with a particle size of 25-45 nm and a specific surface area of ​​600-900 m² / g. The surface of the carbon nanoparticles is carboxylated, with a carboxyl content of 2.5-3.5 mmol / g and a hydroxyl content of 0.8-1.2 mmol / g. The cable interface bonding modification material also includes 1.5-2.5 wt% of a silane-epoxy bifunctional coupling agent, wherein the silane-epoxy bifunctional coupling agent comprises silane groups and epoxy groups, and the molar ratio of the silane groups to the epoxy groups is 1:(1.3-1.4). The hyperbranched polyester multifunctional modifier has 12-15 terminal hydroxyl groups, the hydroxyl value of the hyperbranched polyester multifunctional modifier is 95-115 mgKOH / g, and the degree of branching of the hyperbranched polyester multifunctional modifier is 0.38-0.42; 55-65% of the terminal hydroxyl groups undergo esterification with maleic anhydride to form ester groups, and 80-90% of the remaining unreacted terminal hydroxyl groups undergo ring-opening reaction with the epoxy groups in the silane-epoxy bifunctional coupling agent.

2. The cable interface bonding modified material according to claim 1, characterized in that, The cable interface bonding modification material further includes 0.3-0.8 wt% of antioxidants, which include hindered phenolic antioxidants and sulfur-based synergists. The mass ratio of the hindered phenolic antioxidant to the sulfur-based synergist is (1.4-1.6):

1. The hindered phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the sulfur-based synergist is octadecyl thiodipropionate.

3. A method for preparing a cable interface bonding modified material, used to prepare the cable interface bonding modified material as described in any one of claims 1-2, characterized in that, Includes the following steps: The first step involves weighing the following raw materials by mass percentage: 50-60% matrix resin, 15-20% hyperbranched polyester multifunctional modifier, 25-30% carbon nanoparticles, 1.5-2.5% silane-epoxy bifunctional coupling agent, and 0.3-0.8% antioxidant; wherein the matrix resin is composed of polypropylene and elastomer, and the mass ratio of polypropylene to elastomer is (2.2-2.8):1; The second step involves adding the carbon nanoparticles to xylene at a mass ratio of 1:(4-5) and ultrasonically dispersing for 30-40 minutes to obtain a carbon nanoparticle dispersion. The third step is to dissolve the elastomer in the carbon nanoparticle dispersion and stir it at 80-90°C to obtain an elastomer solution. Fourth step: Mix the hyperbranched polyester multifunctional modifier with maleic anhydride at a molar ratio of 1:(0.6-0.7), add it to the elastomer solution, heat to 115-125℃, and stir for 1-2 hours; add the polypropylene and continue stirring for 0.5-1 hour. Fifth step: Cool down to 90-100℃, dissolve the silane-epoxy bifunctional coupling agent in isopropanol, control the mass fraction to be 3-5%, and slowly add it to the mixture obtained in the fourth step; The sixth step involves removing the solvent by vacuum distillation at a temperature of 85-95°C to obtain the primary product. Step 7: The primary product is melt-blended in a co-rotating twin-screw extruder at an extrusion temperature of 165-175℃ and a screw speed of 300-500 r / min. Step 8: Vacuum dry the extruded product at 70-80℃ for 4-6 hours to obtain the cable interface bonding modified material.

4. The method for preparing the cable interface bonding modified material according to claim 3, characterized in that, In the fifth step, the temperature of the mixture obtained in the fourth step is controlled at 85-90℃; the addition rate of the silane-epoxy bifunctional coupling agent solution is 2-4 ml / min; after the addition is completed, the temperature is increased to 95-100℃ at a rate of 2-3℃ / min, and the reaction is maintained at this temperature for 0.5-1h.

5. The method for preparing the cable interface bonding modified material according to claim 3, characterized in that, Before the sixth step, an antioxidant is added to the product after the fifth step reaction, and the amount of antioxidant added is 0.3-0.8 wt% of the total mass of the product; the antioxidant is composed of hindered phenolic antioxidant and sulfur-based synergist, and the mass ratio of hindered phenolic antioxidant to sulfur-based synergist is (1.4-1.6):1; the pressure of the vacuum distillation is 30-40 kPa, and the distillation time is 2-3 h.