High-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene as well as preparation method and application of high-strength torsion-resistant cable sheath material

Abstract

The invention provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene as well as a preparation method and application thereof, and belongs to the technical field of cable sheath materials. Strengthening and toughening of the composite material are achieved through cooperation of the silicon carbide-based interface reinforcing agent and the modified polyethylene interface toughening agent, the silicon carbide-based interface reinforcing agent serves as a rigid rivet, a silicon carbide core of the silicon carbide-based interface reinforcing agent physically locks two incompatible phases to provide strength, and it is ensured that the silicon carbide-based interface reinforcing agent is compatible with a matrix through a polycaprolactone shell; the modified polyethylene interface toughening agent forms a dynamic hydrogen bond network through self-assembly of a ureido pyrimidone group, dissipates energy when being stressed, and endows the material with toughness and fatigue life; the two additives construct a composite interface, and a multi-scale compatibility strategy of a general compatilizer is combined, so that the contradiction between strength and toughness is effectively solved, and the uniformity, stability and excellent comprehensive performance of a material structure are ensured.

Description

Technical Field

[0001] This invention belongs to the technical field of cable sheath materials, and relates to a high-strength torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene, its preparation method, and its application. Background Technology

[0002] With the rapid development of industrial automation, robotics, and new energy vehicles, the demand for high-performance cable sheath materials is becoming increasingly stringent. These materials must operate under harsh conditions, possessing not only excellent mechanical strength to resist wear and scratches but also superior torsional fatigue life to withstand repeated bending and torsion. Thermoplastic polyurethane is renowned for its excellent elasticity and abrasion resistance, while cross-linked polyethylene combines excellent electrical insulation, heat resistance, and cost advantages. Therefore, blending the two is considered an ideal approach to preparing synergistically reinforced sheath materials that combine the advantages of both. However, technological bottlenecks exist in achieving this goal. Current technological shortcomings are mainly reflected in the following three aspects: First, there is the thermodynamic incompatibility between polar polyurethane and non-polar cross-linked polyethylene. Simple physical blending leads to severe phase separation, forming a large-sized, weakly bonded "sea-island" structure. This fragile interface is highly susceptible to becoming a source of cracks under stress, resulting in poor material mechanical properties, especially prone to delamination under torsional stress, making it completely unsuitable for use.

[0003] Secondly, most current modification methods rely on single, general-purpose compatibilizers. While these compatibilizers can improve interfacial adhesion to some extent, they typically form a static, rigid interfacial layer. This type of interface is effective in improving the static tensile strength of materials, but it cannot effectively dissipate the energy generated by dynamic cyclic stress. Therefore, it has little effect on improving torsional fatigue life and cannot meet the requirements of high-end applications for long-term dynamic stability. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene, its preparation method, and its application. The silicon carbide-based interface reinforcing agent prepared in this application serves as a rigid rivet. Its high-strength silicon carbide whisker cores can bridge and physically lock incompatible phases, providing excellent mechanical strength. Meanwhile, its polycaprolactone shell, compatible with polyurethane, ensures that the reinforcing agent is well dispersed and anchored at the interface, transforming fragile physical contact into a robust mechanical locking structure. Simultaneously, the introduced modified polyethylene interface toughening agent, with its polyethylene backbone, can accumulate at the interface. Its ureidopyrimidinone groups form a dynamically reversible hydrogen bond network through self-assembly. This network dissipates a large amount of energy through fracture and recombination under stress and possesses self-healing capabilities, thus endowing the material with excellent toughness and fatigue life. The rigid skeleton constructed by the reinforcing agent, combined with the dynamic flexible network formed by the toughening agent, constitutes a composite structure that combines rigidity and flexibility at the interface, effectively resolving the traditional contradiction between strength and toughness. Furthermore, the multi-scale compatibility strategy combined with a universal compatibilizer ensures the uniformity and stability of the composite material structure and its excellent comprehensive performance.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene, the method comprising: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent and metal passivator are melt-blended in a twin-screw extruder to obtain a melt. The melt is cooled and pelletized to obtain composite material blend particles. These particles are then mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture. The crosslinking mixture is hot-pressed, cooled and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0006] The preparation method of the silicon carbide-based interface reinforcing agent masterbatch is as follows: S11: Silicon carbide whiskers are immersed in a mixed solution to obtain an activation solution. The solution is then treated, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide is prepared, and deionized water and glacial acetic acid are added to obtain a mixed reaction solution. (3-aminopropyl)triethoxysilane is added, and the mixture is stirred at room temperature for pre-hydrolysis to obtain reaction solution A. The reaction is carried out, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate are mixed, and dibutyltin dilaurate is added to obtain reaction solution B. The reaction is stirred to obtain reaction solution C. Aminated silicon carbide is dispersed in toluene to obtain aminated silicon carbide dispersion. Reaction solution C is added under nitrogen atmosphere to obtain reaction solution D. After the reaction, n-butanol is added and the reaction continues. After centrifugation, washing and drying, silicon carbide-based interface reinforcing agent is obtained. It is mixed with polyurethane and granulated to obtain silicon carbide-based interface reinforcing agent masterbatch.

[0007] The preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine was mixed with isophorone diisocyanate to obtain reaction solution E. The mixture was stirred under a nitrogen atmosphere and cooled to room temperature to obtain a mixture. Hexane was added and stirred. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersion of the intermediate and tetrahydrofuran dispersion of ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F. The mixture was reacted at room temperature, and after rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone was melt-mixed with maleic anhydride-grafted polyethylene wax in a twin-screw extruder and reacted. After cooling and pelletizing, a modified polyethylene interface toughening agent was obtained.

[0008] As a preferred technical solution of the present invention, in step S1, the temperature of the melt blending is 170-190℃, for example, it can be 170℃, 172℃, 174℃, 176℃, 178℃, 180℃, 182℃, 184℃, 186℃, 188℃ or 190℃, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0009] In some alternative embodiments, the mass ratio of the thermoplastic polyurethane to the linear low-density polyethylene is (6:4) to (4:6), for example, it can be 6.0:4.0, 5.8:4.2, 5.6:4.4, 5.4:4.6, 5.2:4.8, 5.0:5.0, 4.8:5.2, 4.6:5.4, 4.4:5.6, 4.2:5.8 or 4.0:6.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0010] In some optional embodiments, the amount of the silicon carbide-based interface reinforcing agent is 0.5-2% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.50%, 0.65%, 0.80%, 0.95%, 1.10%, 1.25%, 1.40%, 1.55%, 1.70%, 1.85% or 2.00%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0011] In some optional embodiments, the amount of the modified polyethylene interface toughening agent is 0.5-2.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.50%, 0.70%, 0.90%, 1.10%, 1.30%, 1.50%, 1.70%, 1.90%, 2.10%, 2.30% or 2.50%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0012] In some optional embodiments, the compatibilizer is maleic anhydride-grafted polyethylene, and the amount of compatibilizer added is 0.5-1% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0013] In some optional embodiments, the antioxidant is antioxidant 1010, and the amount of antioxidant added is 0.3-0.6% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.30%, 0.33%, 0.36%, 0.39%, 0.42%, 0.45%, 0.48%, 0.51%, 0.54%, 0.57% or 0.60%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the anti-hydrolysis agent is carbodiimide, and the amount of anti-hydrolysis agent added is 0.3-0.8% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75% or 0.80%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the metal passivating agent is Naugard® XL-1, and the amount of metal passivating agent added is 0.1-0.3% of the total mass of thermoplastic polyurethane and linear low-density polyethylene, for example, it can be 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28% or 0.30%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the amount of dicumyl peroxide fed is 1.2-1.8% of the mass of linear low-density polyethylene in the mixture, for example, it can be 1.20%, 1.26%, 1.32%, 1.38%, 1.44%, 1.50%, 1.56%, 1.62%, 1.68%, 1.74% or 1.80%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] In some optional embodiments, the mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:(0.8-1.2), for example, it can be 1:0.80, 1:0.84, 1:0.88, 1:0.92, 1:0.96, 1:1.00, 1:1.04, 1:1.08, 1:1.12, 1:1.16 or 1:1.20, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the hot pressing temperature is 175-185°C, for example, it can be 175°C, 176°C, 177°C, 178°C, 179°C, 180°C, 181°C, 182°C, 183°C, 184°C or 185°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0019] In some alternative embodiments, the hot pressing pressure is 10-15 MPa, for example, it can be 10.0 MPa, 10.5 MPa, 11.0 MPa, 11.5 MPa, 12.0 MPa, 12.5 MPa, 13.0 MPa, 13.5 MPa, 14.0 MPa, 14.5 MPa or 15.0 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the hot pressing time is 15-20 min, for example, it can be 15.0 min, 15.5 min, 16.0 min, 16.5 min, 17.0 min, 17.5 min, 18.0 min, 18.5 min, 19.0 min, 19.5 min or 20.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] As a preferred technical solution of the present invention, in step S11, the length of the silicon carbide whisker is 5-15μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm or 15μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution is 1:1:1.5.

[0023] In some optional embodiments, the temperature of the activation solution treatment is 70-80°C, for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the treatment time of the activation solution is 1-2 hours, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the mass fraction of the activated silicon carbide ethanol dispersion is 1-3 wt.%, for example, it can be 1.0 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2.0 wt.%, 2.2 wt.%, 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, or 3.0 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the mass fraction of deionized water in the mixed reaction solution is 0.5-1.0 wt.%, for example, it can be 0.50 wt.%, 0.55 wt.%, 0.60 wt.%, 0.65 wt.%, 0.70 wt.%, 0.75 wt.%, 0.80 wt.%, 0.85 wt.%, 0.90 wt.%, 0.95 wt.% or 1.00 wt.%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the amount of glacial acetic acid added is 0.1-0.3% of the mass of activated silicon carbide, for example, it can be 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28% or 0.30%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the pre-hydrolysis time after adding (3-aminopropyl)triethoxysilane to the mixed reaction solution is 20-30 min, for example, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min or 30 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide is (1-5):100, for example, it can be 1.0:100, 1.4:100, 1.8:100, 2.2:100, 2.6:100, 3.0:100, 3.4:100, 3.8:100, 4.2:100, 4.6:100 or 5.0:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the reaction temperature of the reaction solution A is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the reaction time of the reaction solution A is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] As a preferred technical solution of the present invention, in step S12, the molar ratio of polycaprolactone diol to isophorone diisocyanate is 1:(2-2.2), for example, it can be 1:2.00, 1:2.02, 1:2.04, 1:2.06, 1:2.08, 1:2.10, 1:2.12, 1:2.14, 1:2.16, 1:2.18 or 1:2.20, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the amount of dibutyltin dilaurate fed is 50-150 ppm of the mass of polycaprolactone diol, for example, it can be 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 110 ppm, 120 ppm, 130 ppm, 140 ppm or 150 ppm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the reaction temperature of the reaction solution B is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the reaction time of the reaction solution B is 2-4 hours, for example, it can be 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the mass fraction of the aminated silicon carbide dispersion is 0.5-1.5 wt.%, for example, it may be 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, or 1.5 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the mass ratio of the aminated silicon carbide to polycaprolactone diol is 100:(10-50), for example, it can be 100:10, 100:14, 100:18, 100:22, 100:26, 100:30, 100:34, 100:38, 100:42, 100:46 or 100:50, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the reaction temperature of the reaction solution D is 80-100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the reaction time of the reaction solution D is 3-6 hours, for example, it can be 3.0 hours, 3.3 hours, 3.6 hours, 3.9 hours, 4.2 hours, 4.5 hours, 4.8 hours, 5.1 hours, 5.4 hours, 5.7 hours or 6.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the reaction solution D is followed by the addition of n-butanol and the reaction continues for 30-60 minutes, for example, 30 minutes, 33 minutes, 36 minutes, 39 minutes, 42 minutes, 45 minutes, 48 ​​minutes, 51 minutes, 54 minutes, 57 minutes or 60 minutes, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the amount of n-butanol fed is 5-15% of the molar amount of isophorone diisocyanate fed, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the mass ratio of the silicon carbide-based interface reinforcing agent to polyurethane is (10-20):(90-80), for example, it can be (10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20):(90, 89, 88, 87, 86, 85, 84, 83, 82, 81 or 80), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] As a preferred embodiment of the present invention, in step S13, the molar ratio of 2-amino-4-hydroxy-6-methylpyrimidine to isophorone diisocyanate is 1:(1-1.05), for example, it can be 1:1.000, 1:1.005, 1:1.010, 1:1.015, 1:1.020, 1:1.025, 1:1.030, 1:1.035, 1:1.040, 1:1.045 or 1:1.050, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the reaction liquid E is reacted at a temperature of 80-100°C under a nitrogen atmosphere, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the reaction liquid E is reacted under a nitrogen atmosphere for 4-8 hours, for example, 4.0 hours, 4.4 hours, 4.8 hours, 5.2 hours, 5.6 hours, 6.0 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours, or 8.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the volume ratio of n-hexane to the mixture is (5-10):1, for example, it can be 5.0:1, 5.5:1, 6.0:1, 6.5:1, 7.0:1, 7.5:1, 8.0:1, 8.5:1, 9.0:1, 9.5:1 or 10.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some alternative embodiments, the molar ratio of the intermediate to ethylenediamine is 1:(20-40), for example, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30, 1:32, 1:34, 1:36, 1:38 or 1:40, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, the reaction time of the reaction solution F at room temperature is 2-4 hours, for example, it can be 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some alternative embodiments, the melting and mixing temperature is 140-150°C, for example, it can be 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C or 150°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the reaction temperature after melt mixing is 170-180°C, for example, 170°C, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0051] In some optional embodiments, the reaction time after melt mixing is 5-8 min, for example, it can be 5.0 min, 5.3 min, 5.6 min, 5.9 min, 6.2 min, 6.5 min, 6.8 min, 7.1 min, 7.4 min, 7.7 min or 8.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0052] Secondly, the present invention provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0053] This application addresses the issues of phase separation and weak interfacial bonding in polar polyurethane and non-polar cross-linked polyethylene systems by preparing silicon carbide-based interfacial reinforcing agents and modified polyethylene interfacial toughening agents, thereby producing cable sheath materials with both high mechanical strength and excellent torsional fatigue resistance.

[0054] The silicon carbide-based interface reinforcing agent prepared in this application acts as a rigid interface rivet in composite materials, providing the system with high strength and anti-delamination capability. The silicon carbide-based interface reinforcing agent is a core-shell structured composite nanomaterial. Its core is a high-strength, high-modulus silicon carbide whisker. The one-dimensional needle-like silicon carbide whiskers can partially pierce and anchor in the two incompatible phases of polyurethane and polyethylene under the high shear force of melt blending, bridging the interface like tiny reinforcing bars, effectively suppressing the relative slippage of the two phases under stress through physical locking. Its shell consists of polycaprolactone segments covalently grafted onto the surface of the silicon carbide whiskers through chemical bonds. This solves the problem of poor wettability between silicon carbide whiskers and the polyurethane matrix. Polycaprolactone, as a polyester, has excellent chemical similarity and compatibility with polyurethane in its molecular structure. During melt blending, the polycaprolactone shell can undergo physical entanglement of molecular chains and strong van der Waals forces with the polyurethane matrix, allowing the silicon carbide-based interface reinforcing agent to be stably dispersed in the polyurethane phase and enriched at the interface. Silicon carbide-based interface reinforcing agents transform the originally fragile physical contact interface into a robust interface firmly locked by rivets, providing the composite material with good tensile strength and tear resistance.

[0055] The modified polyethylene interface toughening agent prepared in this application introduces a reversible, dynamic network capable of dissipating stress energy in the interfacial region, thereby endowing the material with excellent fatigue and torsional resistance. This modified polyethylene interface toughening agent is a two-terminal functionalized polymer. Its main chain segments are low-molecular-weight polyethylene chains that are completely compatible with the cross-linked polyethylene matrix, and can preferentially distribute in the polyethylene phase and accumulate in the interfacial region during melt blending. The introduced ureidinidone groups can form a highly stable but dynamically reversible dimer with another ureidinidone group unit through fourfold complementary hydrogen bonds. In the polyethylene phase and interfacial region of the material, these toughening agent molecules self-assemble to form a physically cross-linked supramolecular network. When the material is subjected to torsional or impact stress, this flexible network acts as a "shock absorber": First, a large number of hydrogen bonds undergo large-scale, reversible breakage and recombination. This process absorbs and dissipates enormous energy, preventing stress concentration at a single point and the formation of catastrophic cracks. Second, after the stress is relieved, the broken hydrogen bonds can spontaneously reform at room temperature or operating temperature, giving the interface a certain degree of "self-healing" capability. This dynamic and reversible characteristic is key to the material achieving exceptional torsional fatigue life.

[0056] This application also features synergistic enhancement. The silicon carbide-based interface reinforcing agent constructs a static rigid framework for the interface, providing basic strength and stability; while the modified polyethylene interface toughening agent forms a dynamic flexible network around it, providing toughness and energy dissipation pathways. When the material is under stress, the rigid silicon carbide whiskers are responsible for resisting deformation and transmitting the main load, while the flexible ureidopyrimidinone groups are responsible for absorbing impact energy and passivating microcracks. This composite interface structure resolves the traditional contradiction between strength and toughness, achieving a comprehensive leap in the material's mechanical properties. A small amount of general compatibilizer is also added to the system, which acts as a primary emulsifier, refining the phase domain size of polyurethane and polyethylene on a macroscopic scale, creating the necessary conditions for the two functional additives to function. The silicon carbide-based interface reinforcing agent achieves chemical compatibility with polyurethane through the polycaprolactone shell, while the modified polyethylene interface toughening agent achieves chemical compatibility with polyethylene through polyethylene segments. These three compatibility mechanisms work together to optimize the compatibility of the entire system at different scales, ensuring the uniformity of the final material structure and the stability of its performance.

[0057] Thirdly, the present invention provides a cable whose sheath material is a high-strength torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene.

[0058] Compared with the prior art, the beneficial effects of the present invention are as follows: The silicon carbide-based interface reinforcing agent prepared in this application is a core-shell structured nanomaterial used to enhance the interface of polyurethane / polyethylene composites. Its high-strength silicon carbide whisker core acts as a physical rivet, bridging and locking two incompatible polymer phases, providing mechanical strength; its polycaprolactone shell, compatible with polyurethane, ensures that the reinforcing agent can be well dispersed and anchored at the interface. This reinforcing agent transforms the fragile physical interface into a robust mechanically locked interface, improving the strength and tear resistance of the composite material.

[0059] This application introduces a modified polyethylene interface toughening agent to improve the fatigue and torsional resistance of composite materials. Its polyethylene-compatible backbone ensures its enrichment at the interface, while the introduced ureidopyrimidinone groups construct a molecular damper by forming a dynamically reversible quadruple hydrogen bond network. This network dissipates a large amount of energy under stress through the breaking and recombination of hydrogen bonds and spontaneously repairs itself after stress relief, thereby endowing the material with excellent toughness and fatigue life.

[0060] This application achieves material strengthening and toughening through the synergistic effect of multiple components. First, a silicon carbide-based interface reinforcing agent provides strength as a rigid skeleton, while a modified polyethylene interface toughening agent forms a dynamic flexible network to absorb energy. The combination of the two constructs a rigid-flexible interface, resolving the contradiction between strength and toughness. Furthermore, the universal compatibilizer, the affinity shell of the reinforcing agent, and the compatibility backbone of the toughening agent—these three compatibility mechanisms optimize polymer mixing at different scales, ensuring the uniformity and stability of the material structure and excellent overall performance. Detailed Implementation

[0061] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0062] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0063] Example 1 This embodiment provides a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene and its preparation method. The preparation method of the high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene specifically includes the following steps: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent, and metal passivator are melt-blended in a twin-screw extruder at 185°C to obtain a melt. The melt is then cooled and pelletized to obtain composite material blend particles. The mass ratio of thermoplastic polyurethane to linear low-density polyethylene is 5:5. The feed amount of silicon carbide-based interface reinforcing agent is 1.8% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of modified polyethylene interface toughening agent is 2.2% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of compatibilizer is 0.8% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; and the feed amount of antioxidant is... The amount of the anti-hydrolysis agent is 0.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of the metal passivator is 0.7% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of the metal passivator is 0.25% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; these are mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture, wherein the amount of dicumyl peroxide is 1.7% of the mass of linear low-density polyethylene in the mixture, and the mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:1.1. The crosslinking mixture is hot-pressed at 182℃ and 14MPa for 18min, cooled, and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0064] The preparation method of the silicon carbide-based interface enhancer is as follows: S11: Silicon carbide whiskers with a length of 10 μm were immersed in a mixed solution to obtain an activation solution, wherein the volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution was 1:1:1.5. The solution was treated at 75 °C for 1.5 h, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide with a mass fraction of 2.5 wt.% was prepared, and deionized water and glacial acetic acid were added to obtain a mixed reaction solution, wherein the mass fraction of deionized water in the mixed reaction solution was 0.8 wt.% and the amount of glacial acetic acid added was 0.2% of the mass of activated silicon carbide. After adding (3-aminopropyl)triethoxysilane, the solution was stirred and pre-hydrolyzed at room temperature for 25 min to obtain reaction solution A, wherein the mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide was 4:100. The solution was reacted at 78 °C for 2.5 h, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate were mixed at a molar ratio of 1:2.15, and dibutyltin dilaurate was added to obtain reaction solution B, wherein the amount of dibutyltin dilaurate added was 120 ppm of the mass of polycaprolactone diol. The mixture was stirred at 75°C for 3.5 h to obtain reaction solution C. Aminated silicon carbide was dispersed in toluene to obtain an aminated silicon carbide dispersion with a mass fraction of 1.2 wt.%. Reaction solution C was added under a nitrogen atmosphere to obtain reaction solution D, wherein the mass ratio of aminated silicon carbide to polycaprolactone diol was 100:40. The mixture was reacted at 95°C for 5 h, and then n-butanol was added and the reaction was continued for 50 min, wherein the amount of n-butanol added was 12% of the molar amount of isophorone diisocyanate. The mixture was centrifuged, washed and dried to obtain a silicon carbide-based interface reinforcing agent. This agent was mixed with polyurethane at a mass ratio of 15:85 and granulated to obtain a silicon carbide-based interface reinforcing agent masterbatch.

[0065] The preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine and isophorone diisocyanate were mixed at a molar ratio of 1:1.04 to obtain reaction solution E. The mixture was stirred at 95°C for 7 h under a nitrogen atmosphere, cooled to room temperature to obtain a mixture, and n-hexane was added and stirred, wherein the volume ratio of n-hexane to the mixture was 8:1. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersions of the intermediate and ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F, wherein the molar ratio of the intermediate to ethylenediamine was 1:35. The mixture was reacted at room temperature for 3.5 h, and after rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone and maleic anhydride-grafted polyethylene wax were melt-mixed in a twin-screw extruder at 145°C and reacted at 175°C for 7 min. After cooling, the mixture was pelletized to obtain a modified polyethylene interface toughening agent.

[0066] Example 2 This embodiment provides a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene and its preparation method. The preparation method of the high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene specifically includes the following steps: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent, and metal passivator are melt-blended in a twin-screw extruder at 170°C to obtain a melt. The melt is then cooled and pelletized to obtain composite material blend particles. The mass ratio of thermoplastic polyurethane to linear low-density polyethylene is 6:4. The feed amount of silicon carbide-based interface reinforcing agent is 0.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of modified polyethylene interface toughening agent is 0.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of compatibilizer is 0.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; and the feed amount of antioxidant is... The amount of the anti-hydrolysis agent is 0.3% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of the metal passivator is 0.1% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; these are mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture, wherein the amount of dicumyl peroxide is 1.2% of the mass of linear low-density polyethylene in the mixture, and the mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:0.8. The crosslinking mixture is hot-pressed at 175℃ and 10MPa for 15min, cooled, and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0067] The preparation method of the silicon carbide-based interface enhancer is as follows: S11: Silicon carbide whiskers with a length of 15 μm were immersed in a mixed solution to obtain an activation solution, wherein the volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution was 1:1:1.5. The solution was treated at 80 °C for 2 h, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide with a mass fraction of 1 wt.% was prepared, and deionized water and glacial acetic acid were added to obtain a mixed reaction solution, wherein the mass fraction of deionized water in the mixed reaction solution was 0.5 wt.% and the amount of glacial acetic acid added was 0.3% of the mass of activated silicon carbide. After adding (3-aminopropyl)triethoxysilane, the solution was stirred and pre-hydrolyzed at room temperature for 20 min to obtain reaction solution A, wherein the mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide was 1:100. The solution was reacted at 70 °C for 3 h, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate are mixed at a molar ratio of 1:2, and dibutyltin dilaurate is added to obtain reaction solution B, wherein the amount of dibutyltin dilaurate is 50 ppm of the mass of polycaprolactone diol. The mixture is stirred at 80°C for 2 h to obtain reaction solution C. Aminated silicon carbide is dispersed in toluene to obtain an aminated silicon carbide dispersion with a mass fraction of 0.5 wt.%. Reaction solution C is added under a nitrogen atmosphere to obtain reaction solution D, wherein the mass ratio of aminated silicon carbide to polycaprolactone diol is 100:50. The mixture is reacted at 80°C for 3 h, and then n-butanol is added and the reaction is continued for 30 min, wherein the amount of n-butanol is 5% of the molar amount of isophorone diisocyanate. The mixture is centrifuged, washed and dried to obtain a silicon carbide-based interface reinforcing agent. This agent is then mixed with polyurethane at a mass ratio of 10:90 and granulated to obtain a silicon carbide-based interface reinforcing agent masterbatch.

[0068] The preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine and isophorone diisocyanate were mixed at a molar ratio of 1:1 to obtain reaction solution E. The mixture was stirred at 80°C for 4 hours under a nitrogen atmosphere, cooled to room temperature to obtain a mixture, and n-hexane was added and stirred, wherein the volume ratio of n-hexane to the mixture was 5:1. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersions of the intermediate and ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F, wherein the molar ratio of the intermediate to ethylenediamine was 1:20. The mixture was reacted at room temperature for 2 hours, and after rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone and maleic anhydride-grafted polyethylene wax were melt-mixed in a twin-screw extruder at 150°C and reacted at 180°C for 5 minutes. The mixture was cooled and pelletized to obtain a modified polyethylene interface toughening agent.

[0069] Example 3 This embodiment provides a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene and its preparation method. The preparation method of the high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene specifically includes the following steps: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent, and metal passivator are melt-blended in a twin-screw extruder at 175°C to obtain a melt. The melt is then cooled and pelletized to obtain composite material blend particles. The mass ratio of thermoplastic polyurethane to linear low-density polyethylene is 4.5:5.5. The feed amount of silicon carbide-based interface reinforcing agent is 1.0% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of modified polyethylene interface toughening agent is 1.0% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the feed amount of compatibilizer is 0.6% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; and the feed amount of antioxidant is... The amount of material is 0.4% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of anti-hydrolysis agent is 0.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of metal passivator is 0.15% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; these are mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture, wherein the amount of dicumyl peroxide is 1.4% of the mass of linear low-density polyethylene in the mixture, and the mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:0.9. The crosslinking mixture is hot-pressed at 178℃ and 11MPa for 16min, cooled, and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0070] The preparation method of the silicon carbide-based interface enhancer is as follows: S11: Silicon carbide whiskers with a length of 12 μm were immersed in a mixed solution to obtain an activation solution, wherein the volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution was 1:1:1.5. The solution was treated at 72 °C for 1.8 h, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide with a mass fraction of 1.5 wt.% was prepared, and deionized water and glacial acetic acid were added to obtain a mixed reaction solution, wherein the mass fraction of deionized water in the mixed reaction solution was 0.6 wt.% and the amount of glacial acetic acid added was 0.25% of the mass of activated silicon carbide. After adding (3-aminopropyl)triethoxysilane, the solution was stirred and pre-hydrolyzed at room temperature for 22 min to obtain reaction solution A, wherein the mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide was 2:100. The solution was reacted at 72 °C for 2.8 h, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate were mixed at a molar ratio of 1:2.1, and dibutyltin dilaurate was added to obtain reaction solution B, wherein the amount of dibutyltin dilaurate added was 80 ppm of the mass of polycaprolactone diol. The mixture was stirred at 72°C for 2.5 h to obtain reaction solution C. Aminated silicon carbide was dispersed in toluene to obtain an aminated silicon carbide dispersion with a mass fraction of 0.8 wt.%. Reaction solution C was added under a nitrogen atmosphere to obtain reaction solution D, wherein the mass ratio of aminated silicon carbide to polycaprolactone diol was 100:10. The mixture was reacted at 85°C for 4 h, and then n-butanol was added and the reaction was continued for 40 min, wherein the amount of n-butanol added was 8% of the molar amount of isophorone diisocyanate. The mixture was centrifuged, washed and dried to obtain a silicon carbide-based interface reinforcing agent. This agent was mixed with polyurethane at a mass ratio of 12:88 and granulated to obtain a silicon carbide-based interface reinforcing agent masterbatch.

[0071] The preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine and isophorone diisocyanate were mixed at a molar ratio of 1:1.01 to obtain reaction solution E. The mixture was stirred at 85°C for 5 h under a nitrogen atmosphere, cooled to room temperature to obtain a mixture, and n-hexane was added and stirred, wherein the volume ratio of n-hexane to the mixture was 6:1. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersions of the intermediate and ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F, wherein the molar ratio of the intermediate to ethylenediamine was 1:25. The mixture was reacted at room temperature for 2.5 h, and after rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone and maleic anhydride-grafted polyethylene wax were melt-mixed in a twin-screw extruder at 148°C and reacted at 172°C for 6 min. After cooling, the mixture was pelletized to obtain a modified polyethylene interface toughening agent.

[0072] Example 4 This embodiment provides a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene and its preparation method. The preparation method of the high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene specifically includes the following steps: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent, and metal passivator are melt-blended in a twin-screw extruder at 190°C to obtain a melt. The melt is then cooled and pelletized to obtain composite material blend particles. The mass ratio of thermoplastic polyurethane to linear low-density polyethylene is 4:6. The amount of silicon carbide-based interface reinforcing agent is 2% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of modified polyethylene interface toughening agent is 2.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of compatibilizer is 1% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; and the amount of antioxidant is... The total mass of thermoplastic polyurethane and linear low-density polyethylene is 0.6%; the amount of anti-hydrolysis agent is 0.8% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; the amount of metal passivator is 0.3% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; these are mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture, wherein the amount of dicumyl peroxide is 1.8% of the mass of linear low-density polyethylene in the mixture, and the mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:1.2. The crosslinking mixture is hot-pressed at 185℃ and 15MPa for 20min, cooled, and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

[0073] The preparation method of the silicon carbide-based interface enhancer is as follows: S11: Silicon carbide whiskers with a length of 5 μm were immersed in a mixed solution to obtain an activation solution, wherein the volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution was 1:1:1.5. The solution was treated at 70 °C for 1 h, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide with a mass fraction of 3 wt.% was prepared, and deionized water and glacial acetic acid were added to obtain a mixed reaction solution, wherein the mass fraction of deionized water in the mixed reaction solution was 1.0 wt.%, and the amount of glacial acetic acid added was 0.1% of the mass of activated silicon carbide. After adding (3-aminopropyl)triethoxysilane, the solution was stirred and pre-hydrolyzed at room temperature for 30 min to obtain reaction solution A, wherein the mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide was 5:100. The solution was reacted at 80 °C for 2 h, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate were mixed at a molar ratio of 1:2.2, and dibutyltin dilaurate was added to obtain reaction solution B, wherein the amount of dibutyltin dilaurate added was 150 ppm of the mass of polycaprolactone diol. The mixture was stirred at 70°C for 4 h to obtain reaction solution C. Aminated silicon carbide was dispersed in toluene to obtain an aminated silicon carbide dispersion with a mass fraction of 1.5 wt.%. Reaction solution C was added under a nitrogen atmosphere to obtain reaction solution D, wherein the mass ratio of aminated silicon carbide to polycaprolactone diol was 100:30. The mixture was reacted at 100°C for 6 h, and then n-butanol was added and the reaction was continued for 60 min, wherein the amount of n-butanol added was 15% of the molar amount of isophorone diisocyanate. The mixture was centrifuged, washed and dried to obtain a silicon carbide-based interface reinforcing agent. This agent was mixed with polyurethane at a mass ratio of 20:80 and granulated to obtain a silicon carbide-based interface reinforcing agent masterbatch.

[0074] The preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine and isophorone diisocyanate were mixed at a molar ratio of 1:1.05 to obtain reaction solution E. The mixture was stirred at 100°C for 8 hours under a nitrogen atmosphere. After cooling to room temperature, a mixture was obtained. Hexane was added and stirred, with a volume ratio of hexane to the mixture of 10:1. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersions of the intermediate and ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F, with a molar ratio of the intermediate to ethylenediamine of 1:40. The mixture was reacted at room temperature for 4 hours. After rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone and maleic anhydride-grafted polyethylene wax were melt-mixed in a twin-screw extruder at 140°C and reacted at 170°C for 8 minutes. After cooling and pelletizing, a modified polyethylene interface toughening agent was obtained.

[0075] Comparative Example 1 This comparative example provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene. The difference from Example 1 is that no silicon carbide-based interface reinforcing agent and modified polyethylene interface toughening agent are added. Other operating steps and process parameters are exactly the same as in Example 1.

[0076] Comparative Example 2 This comparative example provides a high-strength torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene. The difference from Example 1 is that no modified polyethylene interface toughening agent is added, while the other operating steps and process parameters are exactly the same as in Example 1.

[0077] Comparative Example 3 This comparative example provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene. The difference from Example 1 is that no silicon carbide-based interface reinforcing agent is added, while the other operating steps and process parameters are exactly the same as in Example 1.

[0078] Comparative Example 4 This comparative example provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene. The difference from Example 1 is that unmodified silicon carbide whiskers are used instead of silicon carbide-based interface reinforcing agents. Other operating steps and process parameters are exactly the same as in Example 1.

[0079] Comparative Example 5 This comparative example provides a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene. The difference from Example 1 is that conventional polyolefin elastomer POE is used instead of the modified polyethylene interface toughening agent. Other operating steps and process parameters are exactly the same as in Example 1.

[0080] The performance of the high-strength torsion-resistant cable sheath materials based on polyurethane / cross-linked polyethylene in Examples 1-4 and Comparative Examples 1-5 was tested, and the specific process is as follows: The tensile strength and elongation at break of the samples were tested according to GB / T 1040.1-2025. The tear strength of the test samples was determined according to GB / T 529-2008; Dynamic fatigue resistance test: The sample is made into a long strip, one end is fixed, and the other end is driven by a motor to perform cyclic torsion at a torsion angle of 120°, a fixed frequency of 60 times / min, and a torsion distance of 500mm. The number of cycles when the sample completely breaks is recorded.

[0081] The test results are shown in Table 1.

[0082] Table 1: Performance test results of high-strength torsion-resistant cable sheath materials based on polyurethane / crosslinked polyethylene in Examples 1-4 and Comparative Examples 1-5 The test results from Example 1 and Comparative Example 1 show that without the addition of silicon carbide-based interface reinforcing agents and modified polyethylene interface toughening agents, the system lacks effective interface control components. The inherent thermodynamic incompatibility between polyurethane and polyethylene leads to severe macroscopic phase separation, forming a coarse "sea-island" structure with extremely weak interfacial bonding. This fragile interface cannot effectively transfer stress and becomes a convenient channel for crack initiation and propagation when the material is under stress, resulting in deterioration of tensile strength, elongation at break, and tear strength. Since the structure experiences interfacial debonding and failure even under minor cyclic stress, its dynamic fatigue resistance also decreases.

[0083] The test results from Example 1 and Comparative Example 2 show that, without the addition of modified polyethylene interface toughening agent, although the system possesses a rigid mechanically locked interface provided by the silicon carbide-based interface reinforcing agent, it lacks the ability to form a dynamic flexible network around it. Therefore, the tensile strength does not change significantly due to interface reinforcement, but the rigid silicon carbide particles also introduce stress concentration, leading to a decrease in the material's elongation at break in the absence of an effective energy dissipation mechanism. Since cyclic stress cannot be dissipated through the reversible fracture and recombination of the hydrogen bond network, stress accumulation ultimately leads to a decline in its dynamic fatigue resistance.

[0084] The test results from Example 1 and Comparative Example 3 show that, without the addition of silicon carbide-based interface reinforcing agents, although the system possesses a dynamic energy-dissipating network provided by the modified polyethylene interface toughening agent, it lacks strong interfacial physical anchoring. While the interface is flexible, its bonding strength is insufficient to withstand and transmit high stress, leading to a decrease in the tensile strength of the material. Although the presence of the dynamic hydrogen bond network endows the material with excellent flexibility (high elongation at break) and a certain degree of fatigue resistance, the lack of a stable "rigid skeleton" means that the interface will gradually slip and damage under continuous cyclic stress, thus limiting its final dynamic fatigue resistance.

[0085] The test results from Example 1 and Comparative Example 4 show that using unmodified silicon carbide whiskers instead of the silicon carbide-based interface reinforcing agent lacks the polycaprolactone shell layer that is compatible with polyurethane. The surface of the unmodified silicon carbide whiskers is incompatible with both the polyurethane and polyethylene matrices, and they readily agglomerate during melt blending, forming macroscopic defects. These agglomerates not only fail to reinforce the interface but also become severe stress concentration sources, disrupting the continuity of the matrix. Consequently, the tensile strength, elongation at break, tear strength, and dynamic fatigue resistance of the material all show significant deterioration.

[0086] The test results from Example 1 and Comparative Example 5 show that using conventional polyolefin elastomer POE to replace the modified polyethylene interface toughening agent lacks a dynamic, reversible hydrogen bond network. Although POE, as an effective toughening agent, can absorb energy through its viscoelastic deformation, imparting good toughness to the material and maintaining high levels of elongation at break and tear strength, this viscoelastic energy dissipation mechanism is far less recoverable than the large-scale, reversible fracture and recombination of the hydrogen bond network. Therefore, in cyclic torsion tests, the energy dissipation capacity of the POE system is limited, leading to a deterioration in its dynamic fatigue resistance.

[0087] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene, characterized in that, The preparation method includes: S1: Thermoplastic polyurethane, linear low-density polyethylene, silicon carbide-based interface reinforcing agent masterbatch, modified polyethylene interface toughening agent, compatibilizer, antioxidant, anti-hydrolysis agent and metal passivator are melt-blended in a twin-screw extruder to obtain a melt. The melt is cooled and pelletized to obtain composite material blend particles. These particles are then mixed with dicumyl peroxide and triallyl isocyanurate to obtain a crosslinking mixture. The crosslinking mixture is hot-pressed, cooled and demolded to obtain a high-strength torsion-resistant cable sheath material based on polyurethane / crosslinked polyethylene.

2. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 1, characterized in that, In S1: The mass ratio of the thermoplastic polyurethane to the linear low-density polyethylene is (6:4)-(4:6); The amount of the silicon carbide-based interface reinforcing agent added is 0.5-2% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; The amount of the modified polyethylene interface toughening agent added is 0.5-2.5% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; The compatibilizer is maleic anhydride-grafted polyethylene, and the amount of compatibilizer added is 0.5-1% of the total mass of thermoplastic polyurethane and linear low-density polyethylene.

3. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 1, characterized in that, In S1: The antioxidant is antioxidant 1010, and the amount of antioxidant added is 0.3-0.6% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; The anti-hydrolysis agent is carbodiimide, and the amount of anti-hydrolysis agent added is 0.3-0.8% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; The metal passivating agent is Naugard® XL-1, and the amount of metal passivating agent added is 0.1-0.3% of the total mass of thermoplastic polyurethane and linear low-density polyethylene; The amount of dicumyl peroxide added is 1.2-1.8% of the mass of linear low-density polyethylene in the mixture; The mass ratio of dicumyl peroxide to triallyl isocyanurate is 1:(0.8-1.2).

4. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 1, characterized in that, In S1, the preparation method of the silicon carbide-based interface reinforcing agent masterbatch is as follows: S11: Silicon carbide whiskers are immersed in a mixed solution to obtain an activation solution. The solution is then treated, washed, and dried to obtain activated silicon carbide. An ethanol dispersion of activated silicon carbide is prepared, and deionized water and glacial acetic acid are added to obtain a mixed reaction solution. (3-aminopropyl)triethoxysilane is added, and the mixture is stirred at room temperature for pre-hydrolysis to obtain reaction solution A. The reaction is carried out, centrifuged, washed, and dried to obtain aminated silicon carbide. S12: Polycaprolactone diol and isophorone diisocyanate are mixed, and dibutyltin dilaurate is added to obtain reaction solution B. The reaction is stirred to obtain reaction solution C. Aminated silicon carbide is dispersed in toluene to obtain aminated silicon carbide dispersion. Reaction solution C is added under nitrogen atmosphere to obtain reaction solution D. After the reaction, n-butanol is added and the reaction continues. After centrifugation, washing and drying, silicon carbide-based interface reinforcing agent is obtained. It is mixed with polyurethane and granulated to obtain silicon carbide-based interface reinforcing agent masterbatch.

5. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 4, characterized in that, In S11: The length of the silicon carbide whiskers is 5-15 μm; The volume ratio of hydrogen peroxide, ammonia, and deionized water in the mixed solution is 1:1:1.

5. The mass fraction of deionized water in the mixed reaction solution is 0.5-1.0 wt.%. The amount of glacial acetic acid added is 0.1-0.3% of the mass of activated silicon carbide; The mass ratio of (3-aminopropyl)triethoxysilane to activated silicon carbide is (1-5):

100.

6. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 4, characterized in that, In S12: The molar ratio of polycaprolactone diol to isophorone diisocyanate is 1:(2-2.2); The amount of dibutyltin dilaurate added is 50-150 ppm of the mass of polycaprolactone diol; The mass ratio of the aminated silicon carbide to polycaprolactone diol is 100:(10-50); The amount of n-butanol added is 5-15% of the molar amount of isophorone diisocyanate added; The mass ratio of the silicon carbide-based interface reinforcing agent to polyurethane is (10-20):(90-80).

7. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 1, characterized in that, In S1, the preparation method of the modified polyethylene interface toughening agent is as follows: S13: 2-Amino-4-hydroxy-6-methylpyrimidine was mixed with isophorone diisocyanate to obtain reaction solution E. The mixture was stirred under a nitrogen atmosphere and cooled to room temperature to obtain a mixture. Hexane was added and stirred. The mixture was filtered, washed, and dried to obtain an intermediate. Tetrahydrofuran dispersion of the intermediate and tetrahydrofuran dispersion of ethylenediamine were prepared separately and mixed in an ice-water bath to obtain reaction solution F. The mixture was reacted at room temperature, and after rotary evaporation, deionized water was added to precipitate the product. The product was filtered, washed, and dried to obtain an amino-terminated ureidopyrimidinone. The amino-terminated ureidopyrimidinone was melt-mixed with maleic anhydride-grafted polyethylene wax in a twin-screw extruder and reacted. After cooling and pelletizing, a modified polyethylene interface toughening agent was obtained.

8. The method for preparing a high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene according to claim 7, characterized in that, In S13: The molar ratio of 2-amino-4-hydroxy-6-methylpyrimidine to isophorone diisocyanate is 1:(1-1.05); The volume ratio of n-hexane to the mixture is (5-10):1; The molar ratio of the intermediate to ethylenediamine is 1:(20-40).

9. A high-strength, torsion-resistant cable sheath material based on polyurethane / cross-linked polyethylene, characterized in that, It is prepared according to any one of claims 1-8.

10. A cable, characterized in that, The sheath material is prepared by the preparation method according to any one of claims 1-8.

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