Corrosion-resistant cable sheath material and method for producing the same

Abstract

The present application relates to the technical field of high polymer materials, and particularly relates to a kind of corrosion-resistant cable sheath material and a preparation method thereof.The sheath material is prepared by compounding amino magnesium ion exchange A-type molecular sieve, dopamine shell silica nanoparticles and phenylboronic acid / octadecyl double-grafted silica nanoparticles as functional fillers, with ethylene-octene copolymer as matrix.Amino Mg-A molecular sieve realizes efficient capture and fixation of chloride ions through ion-dipole interaction and hydrogen bond network;Dopamine shell silica enhances interface bonding strength through catechol and amine double active groups;Phenylboronic acid / octadecyl double-grafted silica constructs dynamic borate ester crosslinking network and hydrophobic barrier, realizing synergistic protection of crack self-healing and moisture barrier.The sheath material significantly improves the long-term corrosion resistance and mechanical stability of cable in harsh environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and particularly relates to a corrosion-resistant cable sheath material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern industry and infrastructure construction, the application demand of cable systems in various complex environments is increasing, especially in marine engineering, chemical plants, coastal areas and high temperature and high humidity industrial environments, cable sheath materials are facing severe corrosive challenges. Although traditional polyolefin cable sheath materials have good insulation performance and mechanical strength, they often show obvious performance degradation under long-term exposure to high salt mist, high humidity and temperature cycle complex environments.

[0003] In the prior art, conventional cable sheath materials are mainly based on polyethylene, polypropylene or ethylene copolymer polyolefin materials. These materials perform well in normal use environment, but in high salt mist environment, chloride ions can penetrate into the sheath material and form ion channels with water molecules between the molecular chains. Especially under alternating temperature and humidity conditions, the repeated penetration and evaporation of water in the material will cause the change of osmotic pressure in the material, resulting in fatigue damage of the microstructure. More importantly, chloride ions have strong migration ability and can continuously diffuse along the weak links of the polymer molecular chain, forming ion enrichment in the interface area, and then causing local stress concentration and micro-crack initiation.

[0004] In order to improve the corrosion resistance of the sheath material, the prior art has tried various methods. Some studies use the addition of inorganic fillers to improve the barrier performance of the material, such as adding silica, calcium carbonate and other fillers to build a physical barrier. However, the compatibility between these traditional fillers and the polyolefin matrix is poor, and defects are easily formed at the interface, which provides a preferential penetration path for water and ions. Another technical route is to add antioxidants, stabilizers and other additives to delay material aging, but this method is mainly aimed at thermal oxidation aging, and has limited effect on salt mist corrosion inhibition.

[0005] In recent years, some improved technologies try to use functional fillers to enhance the performance of the sheath material. For example, using organically modified montmorillonite to improve the barrier performance, or using surface treated inorganic particles to improve the dispersibility. However, these methods still have obvious shortcomings: first, a single functional filler cannot solve the dual problems of ion barrier and interface combination; second, traditional surface modification methods mostly use static chemical bonding, which lacks adaptability to dynamic environmental changes; third, the existing filler system is prone to aggregation and phase separation during long-term use, resulting in gradual failure of the protection effect.

[0006] More importantly, the prior art has a fundamental limitation in the concept of material design. Most of the improvement schemes are based on single mechanism protection strategy, focusing on improving barrier performance or enhancing interface bonding, lacking systematic synergistic design. In the actual corrosion environment, salt spray corrosion is a complex process involving ion transport, interface reaction, stress concentration and crack propagation, and single protection mechanism often has pros and cons, making it difficult to achieve long-term protection.

[0007] In addition, the prior art also has many problems in the material preparation process. The traditional filler pretreatment process is complex, high in cost, and the stability of the treatment effect is difficult to guarantee. In the process of melt blending, the compatibility and dispersion uniformity of different components are difficult to control, and local enrichment or defects are easy to occur. Especially in a multi-component system, the interaction between components is complex, and the optimization of process parameters requires a large number of experiments, resulting in low production efficiency. SUMMARY

[0008] Therefore, the purpose of the present application is to provide a corrosion-resistant cable sheath material and its preparation method, to solve the problem that the interface area of the existing cable sheath material accumulates water and ions under high salt spray and hot and humid environment, leading to micro-crack propagation, and traditional materials cannot effectively inhibit crack propagation and interface debonding.

[0009] Based on the above purpose, the present application provides a corrosion-resistant cable sheath material, which is prepared from the following components by weight: ethylene-octene copolymer 10000 parts, vinyl trimethoxysilane 120-180 parts, dicumyl peroxide 20-40 parts, antioxidant 1010 25-35 parts, antioxidant 168 15-25 parts, dibutyltin dilaurate 6-10 parts, maleic anhydride grafted polyethylene 200-400 parts, aminated Mg-A molecular sieve 700-1300 parts, organic montmorillonite 150-250 parts, dopamine shell silica nanoparticles 20-40 parts, phenylboronic acid / octadecyl double-grafted silica nanoparticles 60-100 parts and polybutadiene diol 30-70 parts.

[0010] Preferably, the ethylene-octene copolymer is ENGAGE 8180, the maleic anhydride grafted polyethylene is SK OREVAC 18300, and the organic montmorillonite is BYK Cloisite 20A.

[0011] The aminated Mg-A molecular sieve is prepared by exchanging 4A molecular sieve with magnesium ions and then modifying with 3-aminopropyl triethoxysilane.

[0012] The dopamine shell silica nanoparticles are prepared by coating the surface of silica nanoparticles with dopamine hydrochloride; the weight ratio of the silica nanoparticles and dopamine hydrochloride is 100:1.5-2.5.

[0013] The phenylboronic acid / octadecyl double-grafted silica nanoparticles are prepared by sequentially modifying the silica nanoparticles with 3-isocyanatopropyl triethoxysilane, grafting 3-aminophenylboronic acid and grafting octadecyltrimethoxysilane; the weight ratio of the silica nanoparticles, 3-isocyanatopropyl triethoxysilane, 3-aminophenylboronic acid and octadecyltrimethoxysilane is 80:6-10:10-14:6-10.

[0014] Preferably, the silica nanoparticles are prepared by the Stöber method.

[0015] Preferably, the specific preparation steps of the aminated Mg-A molecular sieve are as follows: ion exchange of 4A molecular sieve in a magnesium chloride hexahydrate aqueous solution at 65-75℃ for 90-150min, washing, drying to obtain Mg-A type molecular sieve; reacting the Mg-A type molecular sieve with 3-aminopropyl triethoxysilane in anhydrous ethanol for 120-240min, separating, drying, activating to obtain the aminated Mg-A molecular sieve.

[0016] Preferably, the magnesium chloride hexahydrate aqueous solution is prepared by mixing magnesium chloride hexahydrate and deionized water in a weight ratio of 18-22:100.

[0017] Preferably, the bath ratio of the 4A molecular sieve in the magnesium chloride hexahydrate aqueous solution is 10:118-122 by weight.

[0018] Preferably, the ion exchange is repeated for 2-4 times.

[0019] Preferably, the weight ratio of the Mg-A type molecular sieve and 3-aminopropyl triethoxysilane is 100:4-6.

[0020] Preferably, the activation is carried out at 100-130℃ for 90-150min.

[0021] Preferably, the specific preparation steps of the phenylboronic acid / octadecyl double-grafted silica nanoparticles are as follows: refluxing silica nanoparticles with 3-isocyanate propyl triethoxysilane in anhydrous toluene at 80℃ for 150-210 min to obtain isocyanate-modified silica nanoparticles; reacting the isocyanate-modified silica nanoparticles with 3-aminophenylboronic acid and triethylamine in anhydrous toluene at 70-75℃ for 150-210 min to obtain phenylboronic acid-grafted silica nanoparticles; refluxing the phenylboronic acid-grafted silica nanoparticles with octadecyl trimethoxysilane in anhydrous toluene at 80℃ for 100-180 min, and vacuum drying to obtain phenylboronic acid / octadecyl double-grafted silica nanoparticles.

[0022] Preferably, the vacuum drying is performed at 70-90℃ for 180-300 min.

[0023] Preferably, the weight average molecular weight of the polybutadiene diol is 2500-3500.

[0024] Further, the application also provides a preparation method of the corrosion-resistant cable sheath material, comprising the following steps:

[0025] S1: preparing amino-Mg-A molecular sieve;

[0026] S2: preparing dopamine shell silica nanoparticles;

[0027] S3: preparing phenylboronic acid / octadecyl double-grafted silica nanoparticles;

[0028] S4: adding ethylene-octene copolymer, vinyl trimethoxysilane, dicumyl peroxide, antioxidant 1010, antioxidant 168 and dibutyltin dilaurate at the feeding port of the extruder, and adjusting the temperature of each zone of the cylinder to 145-155 / 165-175 / 175-185 / 175-185℃, the die temperature to 170-180℃, the screw rotation speed to 180-230 rpm, and protecting under nitrogen; adding maleic anhydride grafted polyethylene, amino-Mg-A molecular sieve and organic montmorillonite at the side feeding port, adjusting the temperature of each zone of the cylinder to 170-180℃, and blending for 1.5-2.5 min and vacuum devolatilizing; adding dopamine shell silica nanoparticles, phenylboronic acid / octadecyl double-grafted silica nanoparticles and polybutadiene diol at the side feeding port, adjusting the temperature of each zone of the cylinder to 160-170℃, and discharging, water-cooling and granulating to obtain the corrosion-resistant cable sheath material.

[0029] The application has the following beneficial effects:

[0030] Enhanced ion capture and fixation effect: The present application realizes efficient capture and firm fixation of corrosive ions through the unique design of amino-modified magnesium ion-exchanged 4A molecular sieves. After magnesium ion exchange, the pore structure of 4A molecular sieves is optimized and controlled, forming specific ion capture sites. The amino modification further introduces amino functional groups on the surface of the molecular sieves, significantly enhancing the adsorption capacity of corrosive ions such as chloride ions through ion-dipole interaction and hydrogen bond network. The synergistic effect of this double modification enables the sheath material to intercept and fix the permeating corrosive ions at the source, effectively blocking the migration and enrichment of ions in the material interior, and fundamentally inhibiting the occurrence of corrosion reactions.

[0031] Improved interfacial bonding and dispersion stability: The introduction of dopamine-coated silica nanoparticles significantly improves the interfacial bonding performance. Dopamine molecules have unique catechol and amine groups, which can form a multi-point anchoring adhesion structure with the polyolefin matrix. The catechol group is tightly bonded to the matrix molecular chain through hydrogen bonding and π-π interaction, while the amine group forms a firm amide bond with the anhydride group in maleic anhydride grafted polyethylene. This multi-chemical interaction mechanism ensures the uniform dispersion of nanoparticles in the matrix, avoiding the agglomeration phenomenon that often occurs with traditional fillers, and significantly enhancing the mechanical strength and fatigue resistance of the interfacial region.

[0032] Dynamic repair and hydrophobic barrier system: Benzene boronic acid and octadecyl double-grafted silica nanoparticles form a unique dynamic repair and hydrophobic barrier synergistic protection system. The benzene boronic acid group can form reversible borate ester bonds with the hydroxyl groups of polybutadiene diols, constructing a dynamic crosslinking network. When the material is subjected to external force and generates microcracks, these reversible bonds can reform after stress release, achieving self-healing of the cracks. At the same time, the hydrophobic barrier formed by the octadecyl long chain at the interface effectively prevents water molecules from penetrating into the crack tip, cutting off the transmission path of the corrosion medium. The synergistic effect of this dual mechanism of dynamic repair and passive barrier significantly improves the long-term stability of the material under cyclic stress and corrosive environment.

[0033] Optimized interfacial stress distribution and energy dissipation: The multi-component synergistic design of the present application realizes effective dispersion of interfacial stress and gradient dissipation of energy. Amino-modified magnesium ion-exchanged 4A molecular sieves provide a stress transfer support skeleton as a rigid phase; dopamine-coated silica nanoparticles achieve stress buffering between rigid particles and flexible matrix through a flexible organic shell; and benzene boronic acid / octadecyl double-grafted silica nanoparticles achieve stress time relaxation through a dynamic crosslinking network. This multi-level stress regulation mechanism enables the material to disperse and dissipate strain energy through multiple paths when subjected to external load, avoiding brittle failure caused by local stress concentration, and significantly improving the toughness and impact resistance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings required to be used in the embodiments or prior art description will be briefly introduced as follows.

[0035] Figure 1 The preparation process flow chart of the corrosion-resistant cable sheath material according to the present application.

[0036] Figure 2 The infrared spectra of the silica nanoparticles, the phenylboronic acid grafted silica nanoparticles and the phenylboronic acid / octadecyl double-grafted silica nanoparticles in Example 2 of the present application.

[0037] Figure 3 The thermogravimetric curve of the cable sheath prepared in Example 2 and Comparative Examples 1-6 of the present application.

[0038] Figure 4 The thermogravimetric differential curve of the cable sheath prepared in Example 2 and Comparative Examples 1-6 of the present application. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific examples.

[0040] Example 1

[0041] Step S1: Preparation of magnesium ion-exchanged aminated 4A molecular sieve

[0042] S11: In a 20L glass reaction kettle, 10000g of deionized water and 1800g of magnesium chloride hexahydrate were added. After stirring and dissolving, the temperature was raised to 65℃, and then 1000g of 4A molecular sieve powder (from Sigma-Aldrich, item number M103741, mesh 60-80) was added. The ion exchange was carried out by stirring for 90min, and then the product was separated by suction filtration and washed with deionized water until no chloride ions were detected. The ion exchange operation was repeated twice. The Mg-A type molecular sieve was dried at 120℃ for 300min;

[0043] S12: 1000g of Mg-A type molecular sieve was dispersed in 5000g of anhydrous ethanol, and 40g of 3-aminopropyltriethoxysilane was added dropwise. The mixture was stirred at room temperature for 120min, and then separated by suction filtration. The product was dried at 60℃ for 600min, and then activated at 100℃ for 90min. The product was ground through a 100 mesh sieve and dried to obtain the aminated Mg-A molecular sieve;

[0044] Step S2: Preparation of dopamine shell silica nanoparticles

[0045] S21: In a 1 L flask, 8000 g of anhydrous ethanol, 1000 g of ammonia water (concentration 28 wt%), 2000 g of deionized water were added and stirred uniformly at 25°C, 500 g of tetraethoxysilane was added dropwise, and the reaction was carried out for 360 min. After centrifugal separation and deionized water washing until neutral, drying was carried out at 60°C for 600 min to obtain silica nanoparticles; S22: 100 g of silica nanoparticles were dispersed in 3000 g of Tris buffer (pH 8.5), 1.5 g of dopamine hydrochloride was added, and stirring was carried out at 25°C for 90 min. After centrifugal separation and deionized water washing, drying was carried out at 60°C for 600 min to obtain dopamine shell silica nanoparticles;

[0046] Step S3: Preparation of phenylboronic acid / octadecyl double-grafted silica nanoparticles

[0047] S31: 80 g of silica nanoparticles were dispersed in 1000 g of anhydrous toluene, 6 g of 3-isocyanatopropyltriethoxysilane was added, and stirring was carried out at 80°C for 150 min. After filtration separation and drying, isocyanate-modified silica nanoparticles were obtained. Then, the nanoparticles were dispersed in 500 g of anhydrous toluene, 10 g of 3-aminophenylboronic acid and 1.5 g of triethylamine were added, and stirring was carried out at 70°C for 150 min. After filtration separation and drying, phenylboronic acid grafted silica nanoparticles were obtained. Then, the nanoparticles were dispersed in 500 g of anhydrous toluene, 6 g of octadecyltrimethoxysilane was added, and reflux reaction was carried out at 80°C for 100 min. After filtration separation and drying, vacuum was maintained at 70°C for 180 min to obtain phenylboronic acid / octadecyl double-grafted silica;

[0048] Step S4: Preparation of corrosion-resistant cable sheath material

[0049] S41: 10000 g of ethylene-octene copolymer (ENGAGE 8180), 120 g of vinyltrimethoxysilane, 20 g of dicumyl peroxide, 25 g of antioxidant 1010, 15 g of antioxidant 168, and 6 g of dibutyltin dilaurate were continuously added to the feeding port of a twin-screw extruder. The barrel temperature was set to 145 / 165 / 175 / 175°C, the die temperature was 170°C, the screw rotation speed was 180 rpm, and nitrogen protection was used with a total residence time of 3.8 min;

[0050] S42: The temperature of each zone of the barrel was adjusted to 170°C, and 200 g of maleic anhydride grafted polyethylene (SK OREVAC 18300), 700 g of aminated Mg-A molecular sieve, and 150 g of organic montmorillonite (BYK Cloisite 20A) were sequentially added to the side feeding port. Blending was carried out for 1.5 min, and vacuum was applied for devolatilization;

[0051] S43: Adjust each temperature zone of the cylinder to 160℃, and sequentially add 20g dopamine shell silica nanoparticles, 60g phenylboronic acid / octadecyl double-grafted silica nanoparticles, and 30g poly(butadiene) glycol (weight average molecular weight 3000) into the side feeding port. Granulate the discharge water to obtain a corrosion-resistant cable sheath material.

[0052] Extrusion curing: immediately after extruding the sheath material on the cable, immerse it in a 82℃ water bath for 420min for hydrothermal curing. After taking out of the bath, dry it with hot air at 55℃ for 20h to obtain a corrosion-resistant cable sheath.

[0053] Example 2:

[0054] Step S1: Preparation of magnesium ion-exchanged aminated 4A molecular sieve

[0055] S11: In a 20L glass reaction kettle, add 10000g deionized water and 2030g magnesium chloride hexahydrate. After stirring and dissolving, heat to 70℃, then add 1000g 4A molecular sieve powder (from Sigma-Aldrich, item number M103741, mesh 60-80 mesh). Stir for 120min for ion exchange, separate by suction filtration, and wash with deionized water until no chloride ions are present. Repeat the ion exchange operation 3 times to ensure complete exchange. Dry at 120℃ for 360min to obtain Mg-A type molecular sieve;

[0056] S12: Disperse 1000g Mg-A type molecular sieve in 5000g anhydrous ethanol, and dropwise add 50g 3-aminopropyltriethoxysilane. Stir at room temperature for 180min, separate by suction filtration, dry at 60℃ for 720min, then activate at 120℃ for 120min, grind through a 100 mesh sieve, and dry to obtain aminated Mg-A molecular sieve;

[0057] Step S2: Preparation of dopamine shell silica nanoparticles

[0058] S21: In a 1L flask, add 8000g anhydrous ethanol, 1000g ammonia water (concentration 28wt%), and 2000g deionized water. Stir uniformly at 25℃, and dropwise add 560g tetraethoxysilane. React for 480min, centrifuge and wash with deionized water until neutral, and dry at 60℃ for 720min to obtain silica nanoparticles;

[0059] S22: Disperse 100g silica nanoparticles in 3000g Tris buffer (pH 8.5), and add 2g dopamine hydrochloride. Stir at 25℃ for 120min, centrifuge and wash with deionized water, and dry at 60℃ for 720min to obtain dopamine shell silica nanoparticles;

[0060] Step S3: Preparation of phenylboronic acid / octadecyl double-grafted silica nanoparticles

[0061] S31: Disperse 80 g of silica nanoparticles in 1000 g of anhydrous toluene, add 8 g of 3-isocyanatopropyltriethoxysilane, stir at 80°C for 180 min, filter and dry to obtain isocyanate-modified silica nanoparticles; redispersed in 500 g of anhydrous toluene, add 12 g of 3-aminophenylboronic acid and 2 g of triethylamine, stir at 70°C for 180 min, filter and dry to obtain phenylboronic acid-grafted silica nanoparticles; redispersed in 500 g of anhydrous toluene, add 8 g of octadecyltrimethoxysilane, reflux at 80°C for 120 min, filter and dry, vacuum at 80°C for 240 min to obtain phenylboronic acid / octadecyl double-grafted silica;

[0062] Step S4: Preparation of corrosion-resistant cable sheath material

[0063] S41: Continuously add 10000 g of ethylene-octene copolymer (ENGAGE 8180), 150 g of vinyltrimethoxysilane, 30 g of dicumyl peroxide, 30 g of antioxidant 1010, 20 g of antioxidant 168 and 8 g of dibutyltin dilaurate into the feeding port of the twin-screw extruder, set the barrel temperature to 150 / 170 / 180 / 180°C, the die temperature to 175°C, the screw rotation speed to 200 rpm, and protect it with nitrogen, with a total residence time of 4.5 min;

[0064] S42: Adjust the temperature of each zone of the barrel to 175°C and run, then add 300 g of maleic anhydride-grafted polyethylene (SK OREVAC 18300), 1000 g of aminated Mg-A molecular sieve, and 200 g of organic montmorillonite (BYK Cloisite 20A) into the side feeding port in sequence, blend for 2 min and vacuumize to remove volatiles;

[0065] S43: Adjust the temperature of each zone of the barrel to 165°C and run, then add 30 g of dopamine shell silica nanoparticles, 80 g of phenylboronic acid / octadecyl double-grafted silica nanoparticles, and 50 g of poly(butadiene) glycol (weight average molecular weight 3000) into the side feeding port in sequence, water-cool and granulate the discharge to obtain the corrosion-resistant cable sheath material.

[0066] Extrusion curing: immediately after extruding the sheath material onto the cable, immerse it in a 85°C water bath for 480 min for hydrothermal curing, then dry it in a hot air oven at 60°C for 24 h to obtain the corrosion-resistant cable sheath.

[0067] Example 3

[0068] Step S1: Preparation of aminated 4A molecular sieve exchanged with magnesium ions

[0069] S11: 10000 g of deionized water, 2200 g of magnesium chloride hexahydrate were added into a 20 L glass reactor, after stirring and dissolving, the temperature was raised to 75 °C, then 1000 g of 4A molecular sieve powder (from Sigma-Aldrich, item number M103741, mesh 60-80 mesh) was added, ion exchange was carried out by stirring for 150 min, and then the product was separated by suction filtration, washed with deionized water until no chloride ions were detected, and the ion exchange operation was repeated 4 times. The product was dried at 120 °C for 420 min to obtain Mg-A type molecular sieve;

[0070] S12: 1000 g of Mg-A type molecular sieve was dispersed in 5000 g of anhydrous ethanol, 60 g of 3-aminopropyl triethoxysilane was added dropwise, stirred at room temperature for 240 min, separated by suction filtration, dried at 60 °C for 840 min, then activated at 130 °C for 150 min, ground through a 100 mesh sieve, and dried to obtain amino-functionalized Mg-A molecular sieve;

[0071] Step S2: Preparation of dopamine-coated silica nanoparticles

[0072] S21: 8000 g of anhydrous ethanol, 1000 g of ammonia water (concentration 28 wt%), and 2000 g of deionized water were added into a 1 L flask, stirred uniformly at 25 °C, and then 640 g of tetraethoxysilane was added dropwise, reacted for 600 min, centrifuged and washed with deionized water until neutral, and then dried at 60 °C for 840 min to obtain silica nanoparticles; S22: 100 g of silica nanoparticles were dispersed in 3000 g of Tris buffer (pH 8.5), 2.5 g of dopamine hydrochloride was added, stirred at 25 °C for 150 min, centrifuged and washed with deionized water, and then dried at 60 °C for 840 min to obtain dopamine-coated silica nanoparticles;

[0073] Step S3: Preparation of phenylboronic acid / octadecyl double-grafted silica nanoparticles

[0074] S31: 80 g of silica nanoparticles were dispersed in 1000 g of anhydrous toluene, 10 g of 3-isocyanatopropyl triethoxysilane was added, stirred at 80 °C for 210 min, filtered and dried to obtain isocyanate-modified silica nanoparticles; then dispersed in 500 g of anhydrous toluene, 14 g of 3-aminophenylboronic acid and 2.5 g of triethylamine were added, stirred at 75 °C for 210 min, filtered and dried to obtain phenylboronic acid-grafted silica nanoparticles; then dispersed in 500 g of anhydrous toluene, 10 g of octadecyltrimethoxysilane was added, refluxed at 80 °C for 180 min, filtered and dried, and then vacuum dried at 90 °C for 300 min to obtain phenylboronic acid / octadecyl double-grafted silica;

[0075] Step S4: Preparation of corrosion-resistant cable sheath material

[0076] S41: 10000 g of ethylene-octene copolymer (ENGAGE 8180), 180 g of vinyl trimethoxysilane, 40 g of dicumyl peroxide, 35 g of antioxidant 1010, 25 g of antioxidant 168 and 10 g of dibutyltin dilaurate were continuously added at the feeding port of the twin-screw extruder, the barrel temperature was set to 155 / 175 / 185 / 185 °C, the die temperature was 180 °C, the screw rotation speed was 230 rpm, nitrogen protection, and the total residence time was 5.2 min;

[0077] S42: The temperature of each zone of the barrel was adjusted to 180 °C and operated, 400 g of maleic anhydride grafted polyethylene (SK OREVAC 18300), 1300 g of aminated Mg-A molecular sieve, 250 g of organic montmorillonite (BYK Cloisite 20A) were sequentially added at the side feeding port, blended for 2.5 min and vacuum devolatilized;

[0078] S43: The temperature of each zone of the barrel was adjusted to 170 °C and operated, 40 g of dopamine shell silica nanoparticles, 100 g of phenylboronic acid / octadecyl double-grafted silica nanoparticles, 70 g of poly(butadiene) glycol (weight average molecular weight 3000) were sequentially added at the side feeding port, water-cooled granulation was performed after discharging, and a corrosion-resistant cable sheath material was obtained. Extrusion curing: immediately after the sheath material was extruded onto the cable, it was placed in a 88 °C water bath for 540 min for hydrothermal curing, and then dried in a 65 °C hot air oven for 28 h to obtain a corrosion-resistant cable sheath.

[0079] Comparative Example 1:

[0080] The difference between Comparative Example 1 and Example 2 is that step S1 does not perform magnesium ion exchange, and directly uses unmodified 4A molecular sieve powder instead of aminated Mg-A molecular sieve, and the amount remains 1000 g.

[0081] Comparative Example 2:

[0082] The difference between Comparative Example 2 and Example 2 is that step S1 performs magnesium ion exchange but does not perform 3-aminopropyl triethoxysilane surface amination treatment, and the rest remains the same.

[0083] Comparative Example 3:

[0084] The difference between Comparative Example 3 and Example 2 is that step S2 does not construct a dopamine shell, and directly uses uncoated silica nanoparticles, and the feeding amount remains 30 g.

[0085] Comparative Example 4:

[0086] The difference between Comparative Example 4 and Example 2 is that step S3 only retains phenylboronic acid grafting and does not perform octadecyl trimethoxysilane hydrophobic modification, and the rest remains the same, and the feeding amount is unchanged at 80 g.

[0087] Comparative Example 5:

[0088] Comparative Example 5 differs from Example 2 in that step S3 only retains octadecyltrimethoxysilane hydrophobic modification, and does not perform phenylboronic acid grafting, and the rest remains unchanged, with a constant feed of 80 g.

[0089] Comparative Example 6:

[0090] Comparative Example 6 differs from Example 2 in that step S43 does not add poly(butadiene) glycol, and the other feed and temperature zone settings remain unchanged.

[0091] Performance test:

[0092] Infrared characterization: KBr tablet, 4000-450 cm -1 .

[0093] Thermogravimetric analysis: After stripping the cable sheath of the examples and comparative examples, cut into 2-3 mm small pieces, nitrogen, 30-800℃, 10℃ / min, record the thermogravimetric curve, and combine with differential processing to obtain the thermogravimetric differential curve.

[0094] Tensile strength and elongation at break: According to GB / T 1040.2-2022 "Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics", dumbbell test sample type 1, tensile rate 50 mm / min, test tensile strength and elongation at break, the results are shown in Table 1.

[0095] Mechanical retention rate after hot air aging: According to GB / T 2951.12-2008 "General test methods for cable and optical cable insulation and sheath materials Part 12: General test methods Hot aging test method", air aging oven 120℃×168h, take out and place at 23℃ / 50%RH for 16h before testing the tensile strength and elongation at break retention rate.

[0096] Neutral salt spray corrosion resistance: According to GB / T 10125-2021 "Artificial atmosphere corrosion test Salt spray test", neutral salt spray test conditions, 5% NaCl, pH 6.8, 35℃, cycle 3000h, detect the corrosion propagation length along the interface of the end face and retest the tensile strength, and calculate the tensile strength retention rate.

[0097] Low temperature bending performance: According to GB / T 2951.14-2008 "General test methods for cable and optical cable insulation and sheath materials Part 14: General test methods Low temperature test", after 4h of heat preservation, check the cracks by bending, select the mandrel diameter Dm=4d based on the cable outer diameter d; continuously wind 6 turns on the mandrel at a speed of about 15s / turn, temperature -40℃, 10x magnification to check the number of cracks, the results are shown in Table 1.

[0098]

[0099] Data analysis:

[0100] As can be seen from the test results of Examples 1-3 in Table 1, the sheath material prepared by the present application shows significant improvement in tensile properties, hot air aging retention rate, tensile retention rate after neutral salt spray, and low temperature bending crack resistance. The reason is that the magnesium ion exchanged 4A molecular sieve forms stable ion capture center after amination modification, which can effectively adsorb and fix moisture and chloride ions; the dopamine shell silica forms multi-point adhesion in the polyolefin matrix through the catechol-silicon oxide network, improving the interfacial bonding strength; the phenylboronic acid and octadecyl double-grafted silica particles form dynamic borate ester crosslinking and hydrophobic barrier in the interface area, which not only realizes crack self-healing under humid heat conditions through reversible bond action, but also inhibits water film and ion penetration. The synergistic effect of the three structural units makes the sheath material maintain high mechanical stability and corrosion resistance in the salt spray-humid- low temperature coupling environment.

[0101] As can be seen from the data of Example 2 and Comparative Example 1 in Table 1, when the filler uses unmodified 4A molecular sieve, the mechanical retention rate of the material in the salt spray environment decreases significantly. The reason is that the 4A molecular sieve which has not been treated by magnesium ion exchange and amination has strong hydrophilicity on the surface and the pore channel is not regulated, and the moisture absorption and expansion leads to interfacial stress concentration, easy to form micro-cracks and debonding; at the same time, it lacks chemical anchoring with ethylene-octene matrix, and ions are easy to migrate and expand along the interface. This shows that magnesium ion exchange and amination modification play a key role in ion fixation and interface stability.

[0102] As can be seen from the data of Example 2 and Comparative Example 2 in Table 1, the molecular sieve which only undergoes magnesium ion exchange without amination has a certain ion capture effect, but has poor compatibility with polyolefin. Due to the lack of anhydride-amine chemical bond provided by 3-aminopropyl triethoxysilane, the bonding force between the molecular sieve and the matrix is insufficient, and the micro-cracks are difficult to close after hot air aging, which further causes the mechanical retention rate to decrease.

[0103] As can be seen from the data of Example 2 and Comparative Example 3 in Table 1, after removing the dopamine shell, the interfacial adhesion between silica and polyolefin is weakened. The absence of catechol structure leads to decreased dispersibility of the particles in the matrix, and the micro-cracks are difficult to close after hot air aging, which further causes the mechanical retention rate to decrease. The presence of dopamine shell not only enhances the interfacial bonding, but also realizes energy dissipation through intermolecular hydrogen bond network.

[0104] As can be seen from the data of Example 2 and Comparative Example 4 in Table 1, when only phenylboronic acid is grafted and lacks an octadecyl hydrophobic layer, dynamic borate ester crosslinking can improve flexibility, but lacks a hydrophobic barrier, and water film is easy to accumulate at the interface, and corrosion spreads obviously after salt spray. The lack of hydrophobic layer destroys the synergistic mechanism of "dynamic repair-barrier parallel".

[0105] As can be seen from the data in Table 1 for Example 2 and Comparative Example 5, the sheath material with only octadecyl long chains exhibits good initial bending performance, but its performance deteriorates after thermal and humid cycling. This is because although the hydrophobic layer reduces moisture intrusion, the lack of a reversible cross-linking network prevents crack self-healing. A single hydrophobic effect is insufficient to support long-term corrosion resistance.

[0106] As can be seen from the data in Table 1 for Example 2 and Comparative Example 6, the lack of diol end-site exchange sites leads to a decrease in the dynamic borate ester network density, a reduction in crack healing rate and efficiency, and a simultaneous decline in mechanical retention after salt spray and aging. The main reason for this is that the equilibrium exchange between boric acid and diol is controlled by available sites and segment migration; a reduction in sites weakens the synergy between reversible crosslinking and energy dissipation.

[0107] from Figure 2 It can be seen that: phenylboronic acid-grafted silica nanoparticles, compared to silica nanoparticles, have a lower content of 1685 cm⁻¹. -1 A new peak for the urea group C=O appears at 1600 / 1510 cm⁻¹. -1 Clearly visible, and the BO-related band appears at ~1340 and ~1200 cm. -1 The double-grafted sample was further examined at 2921 / 2852 cm⁻¹. -1 Significant CH2 stretching and contraction were observed, with values ​​between 1465 and 720 cm. -1 Alkyl characteristics are present, and 3400cm -1 The significant reduction in broadband indicates that the surface hydroxyl groups are covered by the organic layer, and the above evidence proves the successful preparation of phenylboronic acid / octadecyl double-grafted silica.

[0108] from Figure 3 and Figure 4 It can be seen that the thermogravimetric initiation temperature and the main pyrolysis peak temperature of Example 2 are higher than those of the comparative examples. The weight loss in the low-temperature region (≤150°C) is smaller, indicating less hygroscopic and volatile matter. The main peak of the thermogravimetric differential curve shifts to the right from ~448°C in Comparative Example 1 to ~472°C in Example 2. A gentler secondary weak peak (~580-590°C) appears in the high-temperature region, indicating that the inorganic phase and dynamic network synergistically improve thermal stability.

[0109] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A corrosion-resistant cable sheath material, characterized in that, It is prepared from the following components by weight: 10,000 parts of ethylene-octene copolymer, 120-180 parts of vinyltrimethoxysilane, 20-40 parts of dicumyl peroxide, 25-35 parts of antioxidant 1010, 15-25 parts of antioxidant 168, 6-10 parts of dibutyltin dilaurate, 200-400 parts of maleic anhydride-grafted polyethylene, 700-1300 parts of aminated Mg-A molecular sieve, 150-250 parts of organomontmorillonite, 20-40 parts of dopamine-shell silica nanoparticles, 60-100 parts of phenylboronic acid / octadecyl double-grafted silica nanoparticles, and 30-70 parts of polybutadiene glycol; The aminated Mg-A molecular sieve was prepared by magnesium ion exchange of 4A molecular sieve followed by amination modification with 3-aminopropyltriethoxysilane. The dopamine-shelled silica nanoparticles are prepared by coating the surface of silica nanoparticles with dopamine hydrochloride, and the weight ratio of silica nanoparticles to dopamine hydrochloride is 100:1.5-2.

5. The phenylboronic acid / octadecyl double-grafted silica nanoparticles are prepared by sequentially modifying silica nanoparticles with 3-propyltriethoxysilane, grafting with 3-aminophenylboronic acid, and grafting with octadecyltrimethoxysilane. The weight ratio of the silica nanoparticles, 3-propyltriethoxysilane, 3-aminophenylboronic acid, and octadecyltrimethoxysilane is 80:6-10:10-14:6-10.

2. The corrosion-resistant cable sheath material according to claim 1, characterized in that, The ethylene-octene copolymer is designated as ENGAGE 8180, the maleic anhydride-grafted polyethylene as SK OREVAC 18300, and the organomontmorillonite as BYK Cloisite 20A.

3. The corrosion-resistant cable sheath material according to claim 1, characterized in that, The silica nanoparticles were prepared by the Stöber method.

4. The corrosion-resistant cable sheath material according to claim 1, characterized in that, The specific preparation steps of the aminated Mg-A molecular sieve are as follows: 4A molecular sieve is subjected to ion exchange in an aqueous solution of magnesium chloride hexahydrate at 65-75℃ for 90-150 min, washed and dried to obtain Mg-A type molecular sieve; the Mg-A type molecular sieve is reacted with 3-aminopropyltriethoxysilane in anhydrous ethanol for 120-240 min, separated, dried and activated to obtain aminated Mg-A molecular sieve.

5. The corrosion-resistant cable sheath material according to claim 4, characterized in that, The magnesium chloride hexahydrate aqueous solution is prepared by mixing magnesium chloride hexahydrate and deionized water at a weight ratio of 18-22:100; the bath ratio of the 4A molecular sieve in the magnesium chloride hexahydrate aqueous solution is 10:118-122, by weight.

6. The corrosion-resistant cable sheath material according to claim 4, characterized in that, The ion exchange is repeated 2-4 times.

7. The corrosion-resistant cable sheath material according to claim 4, characterized in that, The weight ratio of the Mg-A type molecular sieve to 3-aminopropyltriethoxysilane is 100:4-6.

8. The corrosion-resistant cable sheath material according to claim 1, characterized in that, The specific preparation steps of the phenylboronic acid / octadecyl double-grafted silica nanoparticles are as follows: silica nanoparticles are refluxed with 3-propyltriethoxysilane in anhydrous toluene at 80°C for 150-210 min to obtain isocyanate-modified silica nanoparticles; the isocyanate-modified silica nanoparticles are reacted with 3-aminophenylboronic acid and triethylamine in anhydrous toluene at 70-75°C for 150-210 min to obtain phenylboronic acid-grafted silica nanoparticles; the phenylboronic acid-grafted silica nanoparticles are refluxed with octadecyltrimethoxysilane in anhydrous toluene at 80°C for 100-180 min, and then vacuum dried to obtain phenylboronic acid / octadecyl double-grafted silica nanoparticles.

9. The corrosion-resistant cable sheath material according to claim 1, characterized in that, The weight-average molecular weight of the polybutadiene glycol is 2500-3500.

10. A method for preparing a corrosion-resistant cable sheath material according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Preparation of aminated Mg-A molecular sieves; S2: Preparation of dopamine-shelled silica nanoparticles; S3: Preparation of phenylboronic acid / octadecyl double-grafted silica nanoparticles; S4: Add ethylene-octene copolymer, vinyltrimethoxysilane, dicumyl peroxide, antioxidant 1010, antioxidant 168, and dibutyltin dilaurate to the extruder feed inlet. The barrel temperatures are 145-155 / 165-175 / 175-185 / 175-185℃ respectively, the die temperature is 170-180℃, the screw speed is 180-230 rpm, and nitrogen protection is maintained. Add maleic acid to the side feed inlet. Anhydride-grafted polyethylene, aminated Mg-A molecular sieve, and organomontmorillonite were mixed for 1.5-2.5 minutes with the temperature of each zone of the barrel adjusted to 170-180℃ and then vacuum-devoured. Dopamine-shell silica nanoparticles, phenylboronic acid / octadecyl double-grafted silica nanoparticles, and polybutadiene glycol were added to the side feed inlet. The temperature of each zone of the barrel was adjusted to 160-170℃. The discharged material was water-cooled and granulated to obtain corrosion-resistant cable sheath material.

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