Bending-resistant cable material and preparation method thereof

Abstract

The invention relates to a bending-resistant cable material and a preparation method thereof, and relates to the technical field of power cables, and the bending-resistant cable material comprises a polyester type thermoplastic polyurethane elastomer, a dopamine modified polyester type thermoplastic polyurethane elastomer, ferric acetylacetonate, covalent grafted graphene, an antioxidant and a lubricant. A competitive coordination interface based on iron ions is constructed by introducing a dopamine modified polyester type thermoplastic polyurethane elastomer and covalent grafted graphene, so that the bending resistance is improved. When the material is subjected to bending stress, the stress is effectively transmitted to a dynamic interface through a polymer network, and a pyridine-iron coordination bond with relatively weak binding force is taken as a sacrificial bond and is subjected to reversible fracture preferentially to efficiently dissipate mechanical energy, so that the damage of stress concentration to a covalent bond of a polymer main chain is avoided; then, catechol-iron bonds with stronger binding force are reversibly broken in one step to dissipate energy. The multi-stage sequential fracture mechanism endows the cable material with excellent bending resistance and durability.

Description

Technical Field

[0001] This application relates to the field of power cable technology, and in particular to a bend-resistant cable material and its preparation method. Background Technology

[0002] Power cables, as an important carrier of electrical energy, are widely used in power systems, industrial equipment, building facilities, and rail transportation. With the continuous growth of electricity demand and the increasing complexity of application environments, cables need to withstand frequent dragging, winding, and bending during operation, which places higher demands on the performance of power cables.

[0003] Currently, to address the issue of cable bending resistance, some technical solutions propose using a flexible, flat insulation layer structure and segmented shielding components. This prevents the shielding components from bearing stress during bending, thus enabling repeated, large-amplitude bending. Other solutions enhance the cable's mechanical properties by installing bending-resistant sheets and rods made of specific materials (such as stainless steel or alloy steel) on the outside of the cable shielding layer, or by designing a multi-layered protective structure including reinforcing layers, bending-resistant layers, and buffer layers. While existing technologies improve cable bending resistance to some extent, they often come at the cost of sacrificing the mechanical strength of the materials.

[0004] Therefore, developing a power cable with better bending resistance is of great practical significance. Summary of the Invention

[0005] This application provides a bend-resistant cable material and its preparation method, which has excellent bend resistance.

[0006] Firstly, the bend-resistant cable material provided in this application adopts the following technical solution: A type of bend-resistant cable material, comprising the following components in parts by weight: 95-100 parts of polyester thermoplastic polyurethane elastomer, 8-12 parts of dopamine-modified polyester thermoplastic polyurethane elastomer, 0.3-0.6 parts of acetylacetone iron, 1.5-2.5 parts of covalently grafted graphene, 0.3-0.8 parts of antioxidant, and 0.1-0.3 parts of lubricant; The dopamine-modified polyester thermoplastic polyurethane elastomer has catechol groups grafted onto its surface; the covalently grafted graphene has pyridine groups grafted onto its surface.

[0007] By adopting the above technical solution, polyester-based thermoplastic polyurethane elastomer is used as the cable material matrix to provide it with the necessary basic toughness. Dopamine-modified polyester-based thermoplastic polyurethane elastomer is introduced, and the catechol groups grafted onto its surface endow the cable material matrix with better intrinsic adhesion and toughness. This not only enables the formation of a stronger interface with the filler and improves mechanical properties, but also enhances the adhesion between the cable material and the internal metal conductor, structurally preventing the intrusion of corrosive media caused by interface delamination, thus laying the foundation for corrosion resistance.

[0008] Building upon this, ferric acetylacetone is introduced, which, with its excellent thermal stability and compatibility, ensures processing stability as a crosslinking agent for the polymer network. Crucially, the ferric ions released by ferric acetylacetone can efficiently coordinate with the catechol groups in dopamine-modified polyester thermoplastic polyurethane elastomers, upgrading a linear thermoplastic structure into a dynamically reversible crosslinked network. Through the reversible breaking and rebuilding of coordination bonds, an energy dissipation mechanism is established within the polymer network, forming the physicochemical basis for achieving the bending resistance of cable materials.

[0009] To improve the tear resistance and long-term protection of cable materials, covalently grafted graphene is introduced as a reinforcing framework for the polymer network. Graphene nanosheets themselves, as high-strength materials, significantly enhance the tensile strength, modulus, and tear resistance of the cable material through their mechanical reinforcement effect. Simultaneously, the structure formed within the matrix constitutes a dense physical barrier against the penetration of water, oxygen, and corrosive ions. Furthermore, graphene's inherent high thermal and electrical conductivity provide efficient heat dissipation and antistatic properties, which are crucial for preventing localized overheating and electrostatic hazards in mines.

[0010] Furthermore, pyridine groups are grafted onto the graphene surface. These groups compete with catechol groups for the coordination of iron ions. Since catechol has a stronger coordination ability with iron ions than pyridine, a dynamically balanced ternary competitive coordination interface of "catechol-iron-pyridine" is eventually formed. When dealing with mechanical bending stress, the stress is effectively transferred to the dynamic network reinforced by graphene through the polymer matrix. At the stress concentration point, the relatively weaker "pyridine-iron" coordination bond undergoes reversible breakage first, serving as the first-level energy dissipation mechanism. If the stress continues, the stronger "catechol-iron" coordination bond breaks next, constituting the second-level energy dissipation mechanism, which macroscopically manifests as excellent bending resistance.

[0011] Optionally, the method for preparing the covalently grafted graphene includes the following steps: S1. Place 1 part by weight of graphene nanosheets in a mixed acid solution composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and reflux at 60°C for 4 hours to obtain acidified graphene. S2. The acidified graphene obtained in step S1 is mixed with 5 parts by weight of thionyl chloride and refluxed at 70°C for 12 hours to obtain acyl-chlorographene. S3. The acyl chloride graphene obtained in step S2 is dispersed in 20 parts by weight of N,N-dimethylformamide, and 0.4-0.6 parts by weight of 4-(4-pyridyl)butyric acid and 0.05 parts by weight of 4-dimethylaminopyridine are added. The mixture is reacted at 60°C for 24 hours under nitrogen protection to obtain covalently grafted graphene.

[0012] By adopting the above technical solution, carboxyl groups are first introduced on the graphene surface by using mixed acid reflux, laying the foundation for subsequent covalent grafting; then, the carboxyl groups are converted into highly reactive acyl chloride groups through acyl chloride reaction; and 4-(4-pyridyl)butyric acid is used to carry out an amidation reaction with acyl chloride graphene. This process anchors the pyridine groups on the graphene surface through strong covalent bonds, forming a stable molecular bridging structure.

[0013] This step-by-step construction process ensures the bonding strength between the pyridine-modified layer and graphene, avoiding the risk of interface failure during use. The exposed pyridine groups generated can serve as efficient connection points for subsequent dynamic coordination networks, while the stability of covalent grafting guarantees stress transfer efficiency and interface durability.

[0014] Optionally, the preparation method of the dopamine-modified polyester thermoplastic polyurethane elastomer includes the following steps: S1. Dissolve 10 parts by weight of polyester thermoplastic polyurethane elastomer in 20 parts by weight of N,N-dimethylformamide, add 0.2 parts by weight of dopamine hydrochloride and 0.03 parts by weight of catalyst, and react at 80°C for 6 hours. S2. After the reaction in step S1 is completed, the product is poured into ethanol to precipitate. After washing, it is vacuum dried at 60°C for 24 hours to obtain dopamine-modified polyester thermoplastic polyurethane elastomer.

[0015] By employing the above technical solution, dopamine reacts with polyester-type thermoplastic polyurethane elastomer in DMF solution under mild conditions. This ensures that dopamine molecules are uniformly grafted onto the polyester-type thermoplastic polyurethane elastomer chain through stable amide bonds, maintaining the integrity of the catechol groups and preventing material degradation. Subsequent ethanol precipitation and vacuum drying processes effectively remove unreacted impurities, ensuring product purity.

[0016] Optionally, the dopamine grafting rate of the dopamine-modified polyester thermoplastic polyurethane elastomer is 1.0-2.5 wt%.

[0017] By adopting the above technical solution, the dopamine grafting rate is precisely controlled within the range of 1.0-2.5 wt%. The lower limit ensures that the catechol groups reach an effective density, which can form a sufficiently dense dynamic coordination network with iron ions, providing an efficient energy dissipation mechanism for the material and laying the foundation for its bending resistance. The upper limit prevents the molecular chain rigidity from being too strong and the processing flow from being too dense due to the functional groups, thus ensuring the flexibility and processability of the material.

[0018] Optionally, the antioxidant is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1-2.

[0019] By adopting the above technical solution, 1010 acts as the primary antioxidant, effectively blocking chain oxidation reactions by capturing free radicals generated during processing and use; while 168, as the secondary antioxidant, efficiently decomposes hydroperoxides, preventing their thermal decomposition and generation of new free radicals. This formulation ensures the thermal stability of the material during high-temperature processing and provides long-lasting antioxidant protection during long-term use, effectively inhibiting the degradation and cross-linking of polymer molecular chains, maintaining mechanical properties and appearance stability, and improving the overall weather resistance and service life of the material.

[0020] Optionally, the lubricant includes zinc stearate, ethylene bis-stearamide, and polyethylene wax.

[0021] By employing the above technical solution, zinc stearate, as an internal lubricant, effectively reduces melt viscosity, while ethylene bis-stearamide possesses both internal and external lubricity and improves filler dispersibility. Together, they ensure the melt's fluidity and uniformity during material processing. Simultaneously, polyethylene wax, as a highly efficient external lubricant, forms a lubrication interface between the processing equipment and the polymer melt, working in conjunction with other components to construct a lubrication system from the melt's interior to its surface. This composite lubrication solution not only improves extrusion processing efficiency and prevents material degradation due to shear overheating, but also indirectly enhances the product's surface finish and dimensional stability by improving filler dispersion and reducing internal stress.

[0022] Optionally, the hardness of the polyester-type thermoplastic polyurethane elastomer is 85A-95A.

[0023] By adopting the above technical solution, this hardness range ensures that the material can effectively disperse stress through the entropy elastic change of the molecular chains under frequent bending conditions, avoiding brittle cracking due to excessive hardness or permanent deformation due to excessive softness, thereby improving fatigue resistance. At the same time, the moderate hardness provides a stable mechanical support substrate for the nano-reinforcing phase, ensuring the material's ability to resist mechanical stresses such as wear and tear, while maintaining the flexibility required for cable installation and laying.

[0024] Secondly, this application provides a method for preparing a bend-resistant cable material, comprising the following steps: S1. Heat polyester thermoplastic polyurethane elastomer and dopamine-modified polyester thermoplastic polyurethane elastomer to 200-230℃, melt them, add acetylacetone iron and antioxidant, and disperse them evenly at 500-600 rpm using a high-speed mixer to form a stable composite system. S2. Add covalently grafted graphene and lubricant to the composite system in step S1, and continue stirring until completely dissolved. The temperature is controlled at 110-120℃, and the mixture is stirred for 15-20 minutes. S3. Cool the obtained mixture to room temperature, extrude it into cable material shape using a twin-screw extruder, and then allow it to cool and solidify naturally to finally obtain a bend-resistant cable material.

[0025] By employing the above technical solution, firstly, a polyester-type thermoplastic polyurethane elastomer matrix is ​​melted at a specific temperature, and iron acetylacetone is added. This allows the iron ions to fully react with the catechol groups in the dopamine-modified polyester-type thermoplastic polyurethane elastomer, constructing a stable dynamic coordination network that provides the material with resilience and bending resistance. Subsequently, covalently grafted graphene is added at a controlled temperature, ensuring its uniform dispersion in the matrix while protecting the already formed dynamic network structure. The strong interfacial interaction between graphene and the dynamic network organically combines the mechanical reinforcing effect of graphene with the toughness of the matrix, improving the material's tear resistance and bending resistance. Finally, the internal structure of the material is stabilized and internal stress is reduced through twin-screw extrusion and natural cooling processes. This method, through stepwise feeding and precise temperature control, effectively synergizes the advantages of each component, enabling the cable material to achieve excellent bending resistance.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. By introducing dopamine-modified polyester thermoplastic polyurethane elastomer and covalently grafted graphene to construct an iron-ion-based competitive coordination interface, the bending resistance is improved. When the material is subjected to bending stress, the stress is effectively transferred to this dynamic interface through the polymer network. The relatively weaker pyridine-iron coordination bonds preferentially undergo reversible fracture as sacrificial bonds, efficiently dissipating mechanical energy and thus avoiding stress concentration that could damage the covalent bonds of the polymer backbone. Subsequently, the stronger catechol-iron bonds further undergo reversible fracture to dissipate energy. This multi-level sequential fracture mechanism delays the initiation and propagation of microcracks; and after the stress is removed, all dynamic coordination bonds can be rapidly rebuilt, restoring the material to its original structural integrity, thereby endowing the cable material with excellent bending resistance and durability. Detailed Implementation

[0027] Preparation Example 1 The preparation method of covalently grafted graphene includes the following steps: S1. Place 1 part by weight of graphene nanosheets in a mixed acid solution composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and reflux at 60°C for 4 hours to obtain acidified graphene. S2. The acidified graphene obtained in step S1 is mixed with 5 parts by weight of thionyl chloride and refluxed at 70°C for 12 hours to obtain acyl-chlorographene. S3. The acyl chloride graphene obtained in step S2 is dispersed in 20 parts by weight of N,N-dimethylformamide, and 0.5 parts by weight of 4-(4-pyridyl)butyric acid and 0.05 parts by weight of 4-dimethylaminopyridine are added. The mixture is reacted at 60°C for 24 hours under nitrogen protection to obtain covalently grafted graphene.

[0028] Preparation Example 2 The covalently grafted graphene differs from that in Preparation Example 1 in that the weight of 4-(4-pyridyl)butyric acid in step S3 is 0.4 parts.

[0029] Preparation Example 3 The covalently grafted graphene differs from that in Preparation Example 1 in that the weight of 4-(4-pyridyl)butyric acid in step S3 is 0.6 parts.

[0030] Preparation Example 4 The preparation method of dopamine-modified polyester thermoplastic polyurethane elastomer includes the following steps: S1. Dissolve 10 parts by weight of polyester thermoplastic polyurethane elastomer in 20 parts by weight of N,N-dimethylformamide, add 0.25 parts by weight of dopamine hydrochloride and 0.03 parts by weight of catalyst, and react at 80°C for 6 hours. S2. After the reaction in step S1 is completed, the product is poured into ethanol to precipitate. After washing, it is vacuum dried at 60°C for 24 hours to obtain dopamine-modified polyester thermoplastic polyurethane elastomer.

[0031] Preparation Example 5 The difference between the dopamine-modified polyester thermoplastic polyurethane elastomer and the preparation example 4 is that the weight of dopamine hydrochloride in step S1 is 0.2 parts.

[0032] Preparation Example 6 The difference between the dopamine-modified polyester thermoplastic polyurethane elastomer and the preparation example 4 is that the weight of dopamine hydrochloride in step S1 is 0.3 parts.

[0033] Example 1 A bend-resistant cable material is composed of the following components in parts by weight: 100 parts of polyester thermoplastic polyurethane elastomer, 12 parts of dopamine-modified polyester thermoplastic polyurethane elastomer, 0.45 parts of iron acetylacetone, 2.5 parts of covalently grafted graphene, 0.8 parts of antioxidant, and 0.3 parts of lubricant. Specifically, the dopamine-modified polyester thermoplastic polyurethane elastomer was obtained using Preparation Example 4, with a dopamine grafting rate of 1.0-2.5 wt%. The covalently grafted graphene was obtained using Preparation Example 1. The antioxidant consisted of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1.5. The lubricant included zinc stearate, ethylene bis-stearamide, and polyethylene wax in a mass ratio of 1:1:1. The hardness of the polyester thermoplastic polyurethane elastomer was 85A-95A.

[0034] A method for preparing a bend-resistant cable material includes the following steps: S1. Heat polyester thermoplastic polyurethane elastomer and dopamine-modified polyester thermoplastic polyurethane elastomer to 220°C, melt them, add acetylacetone iron and antioxidant, and disperse them evenly at 500 rpm using a high-speed mixer to form a stable composite system. S2. Add covalently grafted graphene and lubricant to the composite system in step S1, continue stirring until completely dissolved, control the temperature at 120℃, and stir for 15 minutes. S3. Cool the obtained mixture to room temperature, extrude it into cable material shape using a twin-screw extruder, and then allow it to cool and solidify naturally to finally obtain a bend-resistant cable material.

[0035] Example 2 A type of bend-resistant cable material, which differs from Example 1 in that it is composed of the following components in parts by weight: 98 parts of polyester thermoplastic polyurethane elastomer, 10 parts of dopamine-modified polyester thermoplastic polyurethane elastomer, 0.45 parts of iron acetylacetone, 2 parts of covalently grafted graphene, 0.5 parts of antioxidant, and 0.2 parts of lubricant.

[0036] Example 3 A type of bend-resistant cable material, which differs from Example 1 in that it is composed of the following components in parts by weight: 95 parts of polyester thermoplastic polyurethane elastomer, 8 parts of dopamine-modified polyester thermoplastic polyurethane elastomer, 0.45 parts of iron acetylacetone, 1.5 parts of covalently grafted graphene, 0.3 parts of antioxidant, and 0.1 parts of lubricant.

[0037] Example 4 A type of bend-resistant cable material, which differs from Example 1 in that: the weight of iron acetylacetone is 0.3 parts.

[0038] Example 5 A type of bend-resistant cable material, which differs from Example 1 in that: the weight of iron acetylacetone is 0.8 parts.

[0039] Example 6 A bend-resistant cable material differs from Example 1 in that the covalently grafted graphene is specifically obtained using Preparation Example 2.

[0040] Example 7 A bend-resistant cable material differs from Example 1 in that the covalently grafted graphene is specifically obtained using Preparation Example 3.

[0041] Example 8 A type of bend-resistant cable material, which differs from Example 1 in that the dopamine-modified polyester thermoplastic polyurethane elastomer is specifically obtained using Preparation Example 5.

[0042] Example 9 A type of bend-resistant cable material, which differs from Example 1 in that the dopamine-modified polyester thermoplastic polyurethane elastomer is specifically obtained using Preparation Example 6.

[0043] Detection example The bending resistance of the cable material was tested according to the methods in GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurement - Mechanical Properties Test", and the tensile strength retention rate after 30 repeated tensile cycles was tested. The test results are shown in Table 1.

[0044] Table 1 Testing items Tensile strength (MPa) Tensile strength retention rate (%) Example 1 31.3 85 Example 2 31.6 87 Example 3 31.1 84 Example 4 28.7 72 Example 5 30.8 82 Example 6 30.4 77 Example 7 30.6 79 Example 8 29.2 75 Example 9 29.5 78 As shown in Table 1 of Examples 1-9, the performance test data demonstrate that introducing dopamine-modified polyester thermoplastic polyurethane elastomer and covalently grafted graphene to construct an iron-ion-based competitive coordination interface improves bending resistance. When the material is subjected to bending stress, the stress is effectively transferred to this dynamic interface through the polymer network. The relatively weaker pyridine-iron coordination bonds preferentially undergo reversible fracture as sacrificial bonds, efficiently dissipating mechanical energy and thus preventing stress concentration from damaging the covalent bonds of the polymer backbone. Subsequently, the stronger catechol-iron bonds undergo reversible fracture to further dissipate energy. This multi-level sequential fracture mechanism delays the initiation and propagation of microcracks; and after stress removal, all dynamic coordination bonds can be rapidly rebuilt, restoring the material's original structural integrity, thereby endowing the cable material with excellent bending resistance and durability.

[0045] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A type of bend-resistant cable material, characterized in that, It is composed of the following components in parts by weight: 95-100 parts of polyester thermoplastic polyurethane elastomer, 8-12 parts of dopamine-modified polyester thermoplastic polyurethane elastomer, 0.3-0.6 parts of iron acetylacetone, 1.5-2.5 parts of covalently grafted graphene, 0.3-0.8 parts of antioxidant, and 0.1-0.3 parts of lubricant; The dopamine-modified polyester thermoplastic polyurethane elastomer has catechol groups grafted onto its surface; the covalently grafted graphene has pyridine groups grafted onto its surface.

2. The bend-resistant cable material according to claim 1, characterized in that, The method for preparing the covalently grafted graphene includes the following steps: S1. Place 1 part by weight of graphene nanosheets in a mixed acid solution composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and reflux at 55-60℃ for 4 hours to obtain acidified graphene. S2. The acidified graphene obtained in step S1 is mixed with 5-6 parts by weight of thionyl chloride and refluxed at 65-70°C for 10-12 hours to obtain acyl-chlorographene. S3. Disperse the acyl chloride graphene obtained in step S2 in 18-20 parts by weight of N,N-dimethylformamide, and add 0.4-0.6 parts by weight of 4-(4-pyridyl)butyric acid and 0.05-0.06 parts by weight of 4-dimethylaminopyridine. React at 55-60℃ for 20-24 h under nitrogen protection to obtain covalently grafted graphene.

3. The bend-resistant cable material according to claim 1, characterized in that: The preparation method of the dopamine-modified polyester thermoplastic polyurethane elastomer includes the following steps: S1. Dissolve 10 parts by weight of polyester-type thermoplastic polyurethane elastomer in 18-20 parts by weight of N,N-dimethylformamide, add 0.2-0.3 parts by weight of dopamine hydrochloride and 0.03-0.04 parts by weight of catalyst, and react at 75-80℃ for 5-6 hours. S2. After the reaction in step S1 is completed, the product is poured into ethanol to precipitate. After washing, it is vacuum dried at 55-60℃ for 20-24h to obtain dopamine-modified polyester thermoplastic polyurethane elastomer.

4. The bend-resistant cable material according to claim 1, characterized in that, The dopamine grafting rate of the dopamine-modified polyester thermoplastic polyurethane elastomer is 1.0-2.5 wt%.

5. The bend-resistant cable material according to claim 1, characterized in that: The antioxidant is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1-2.

6. The bend-resistant cable material according to claim 1, characterized in that, The lubricant includes zinc stearate, ethylene bis-stearamide, and polyethylene wax.

7. The bend-resistant cable material according to claim 1, characterized in that: The hardness of the polyester-type thermoplastic polyurethane elastomer is 85A-95A.

8. A method for preparing a bend-resistant cable material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Heat polyester thermoplastic polyurethane elastomer and dopamine-modified polyester thermoplastic polyurethane elastomer to 200-230℃, melt them, add acetylacetone iron and antioxidant, and disperse them evenly at 500-600 rpm using a high-speed mixer to form a stable composite system. S2. Add covalently grafted graphene and lubricant to the composite system in step S1, and continue stirring until completely dissolved. The temperature is controlled at 110-120℃, and the mixture is stirred for 15-20 minutes. S3. Cool the obtained mixture to room temperature, extrude it into cable material shape using a twin-screw extruder, and then allow it to cool and solidify naturally to finally obtain a bend-resistant cable material.