Anti-aging insulated power cable

Abstract

The invention relates to the technical field of cables, and provides an anti-aging insulated power cable, which comprises a cable core, an insulating layer and a sheath layer, and the sheath layer comprises the following raw materials by weight: 60-70 parts of polyethylene, 10-20 parts of polypropylene, 30-40 parts of an ethylene-vinyl acetate copolymer, 3-6 parts of a cross-linking agent, 1-3 parts of an antioxidant, 10-15 parts of an inorganic filler, and 4-6 parts of a compatilizer; the ethylene-vinyl acetate copolymer is composed of a first ethylene-vinyl acetate copolymer and a second ethylene-vinyl acetate copolymer, and the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer have the same vinyl acetate content and different melt indexes; the vinyl acetate content of the first ethylene-vinyl acetate copolymer and the vinyl acetate content of the second ethylene-vinyl acetate copolymer are both 18.0%. According to the technical scheme, the problem of poor aging resistance of the cable in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to an aging-resistant insulated power cable. Background Art

[0002] Cables generate heat during the transmission of electricity. If the cable's aging resistance is insufficient and it is exposed to high temperature for a long time, its insulation material will gradually age, harden, and become brittle, and the insulation resistance will decrease, causing the insulation performance to fail and unable to effectively isolate the conductor, thereby causing safety accidents such as leakage and short circuit.

[0003] Inorganic fillers are low-cost and thermally stable, and are often added to cable materials to improve their heat-aging resistance. However, inorganic fillers have inherent shortcomings such as agglomeration and uneven dispersion within the matrix, which can lead to a decrease in mechanical strength and even accelerate the thermal aging process of the cable. Good heat-aging resistance allows cables to maintain stable insulation performance over long periods of time in high-temperature environments, ensuring safe and reliable power transmission.

[0004] Therefore, it is necessary to propose an aging-resistant insulated power cable. Summary of the Invention

[0005] The present invention provides an aging-resistant insulated power cable, which solves the problem of poor aging-resistant performance of cables in the related art.

[0006] The technical solutions of the present invention are as follows: The present invention provides an aging-resistant insulated power cable, comprising a cable core, an insulating layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 60-70 parts of polyethylene, 10-20 parts of polypropylene, 30-40 parts of ethylene-vinyl acetate copolymer, 8-14 parts of ethylene-methacrylate copolymer, 3-6 parts of a cross-linking agent, 1-3 parts of an antioxidant, 10-15 parts of an inorganic filler, and 4-6 parts of a compatibilizer; the ethylene-vinyl acetate copolymer consists of a first ethylene-vinyl acetate copolymer and a second ethylene-vinyl acetate copolymer, the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer having the same vinyl acetate content and different melt indexes; the vinyl acetate content of the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer is both 18.0%.

[0007] As a further technical solution, the melt index of the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer are independently 1.5-30 g / 10 min.

[0008] As a further technical solution, the melt index of the first ethylene-vinyl acetate copolymer is 2.5 g / 10 min, and the melt index of the second ethylene-vinyl acetate copolymer is 8.0 g / 10 min.

[0009] In the present invention, by limiting the melt index of the first ethylene-vinyl acetate copolymer to 2.5 g / 10 min and the melt index of the second ethylene-vinyl acetate copolymer to 8.0 g / 10 min, the dispersibility of the inorganic filler during the processing can be better improved, and the ethylene-vinyl acetate copolymer with a low melt index forms a physical cross-linked network through chain entanglement, and the ethylene-vinyl acetate copolymer with a high melt index fills the gaps in the physical cross-linked network, thereby improving the elongation at break of the cable sheath layer.

[0010] As a further technical solution, the mass ratio of the first ethylene-vinyl acetate copolymer to the second ethylene-vinyl acetate copolymer is 2 to 5:1, for example, it can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, and preferably 3:1.

[0011] As a further technical solution, the inorganic filler is a composite inorganic filler, and the raw materials of the composite inorganic filler include talc powder and a hydroxyl-containing compound; the hydroxyl-containing compound includes a first hydroxyl-containing compound and a second hydroxyl-containing compound, the first hydroxyl-containing compound includes one of 3,5-dichloro-4-hydroxybenzaldehyde and 2,4-dichloro-5-aminophenol, preferably 4-dichloro-5-aminophenol, and the second hydroxyl-containing compound is cyclohexyl-1,4-dimethanol monovinyl ether.

[0012] The addition of inorganic fillers in the present invention can improve the aging resistance of the cable sheath layer, and the raw materials of the composite inorganic filler also contain two hydroxyl-containing compounds. The addition of the two hydroxyl-containing compounds can better improve the aging resistance of the cable sheath layer. Moreover, when the first hydroxyl-containing compound is preferably 4-dichloro-5-aminophenol, the aging resistance of the cable sheath layer can be further improved.

[0013] As a further technical solution, the preparation method of the composite inorganic filler is as follows: adding a hydroxyl-containing compound into a solvent and dispersing the mixture uniformly, adding talcum powder, mixing the mixture, and drying the mixture to obtain the composite inorganic filler.

[0014] The composite inorganic filler in the present invention includes a hydroxyl-containing compound. The hydroxyl-containing compound can better improve the problem of easy agglomeration of the inorganic filler itself, and on the other hand, it can improve the poor compatibility of the inorganic filler with the polymer body, and can better improve the aging resistance of the cable sheath layer.

[0015] As a further technical solution, the mixing temperature is 35~45°C, for example, it can be 35°C, 36°C, 37°C, 40°C, 42°C, 45°C, preferably 40°C, and the mixing time is 1.5~2.5h, for example, it can be 1h, 1.2h, 1.3h, 1.5h, 1.6h, 1.8h, 2.0h, 2.2h, 2.5h, preferably 2.0h.

[0016] As a further technical solution, the solvent is anhydrous ethanol.

[0017] As a further technical solution, the hydroxyl-containing compound is 4% to 6% of the mass of the talc powder, for example, it can be 4.5%, 5%, 5.5%, 6%, and preferably 5%.

[0018] As a further technical solution, the cross-linking agent is a peroxide cross-linking agent, for example, it can be a peroxide cross-linking agent DCP or a peroxide cross-linking agent TAIC.

[0019] In the present invention, the addition of a cross-linking agent can cause a cross-linking reaction between polyethylene molecular chains to form a three-dimensional network structure. This structure restricts the movement of the molecular chains, improves the heat resistance of the material, makes it less likely for the molecular chains to slip and deform due to heat, and reduces aging degradation caused by thermal oxidation.

[0020] As a further technical solution, the antioxidant includes one or more of phosphite antioxidants, amine antioxidants, and phenolic antioxidants.

[0021] As a further technical solution, the phenolic antioxidant includes one of antioxidant 1010 and antioxidant 1076.

[0022] The addition of the antioxidant in the present invention can reduce the generation of free radicals during the preparation and use of the cable sheath layer, inhibit thermal oxidation reactions, delay the aging of the material, and improve the aging resistance of the cable sheath layer.

[0023] As a further technical solution, the compatibilizer includes maleic anhydride grafted polyethylene.

[0024] The present invention also proposes a method for preparing an aging-resistant insulated power cable, comprising the following steps: S1. Extruding the insulation layer material on the outside of the cable core to obtain a semi-finished cable; S2. After uniformly mixing the raw materials of the sheath layer, the raw materials are extruded onto the outer side of the semi-finished cable to obtain an aging-resistant insulated power cable.

[0025] The working principle and beneficial effects of the present invention are: The present invention adds two ethylene-vinyl acetate copolymers with the same vinyl acetate content but different melt indexes to the cable sheath layer, thereby improving the elongation at break of the cable sheath layer. In existing technologies, the addition of ethylene-vinyl acetate copolymers primarily utilizes the vinyl acetate monomer units to improve the toughness of the cable sheath layer. However, the present invention limits the melt index based on an optimal vinyl acetate content of 18.0%, allowing ethylene-vinyl acetate copolymers with different melt indexes to work synergistically. This also improves the dispersibility of inorganic fillers during processing, further increasing the elongation at break of the cable sheath layer. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] In the following examples and comparative examples: Polyethylene: DGDA-3485 NT, Dow Chemical, USA; Polypropylene: RI83C, Samsung, South Korea; Ethylene methacrylate copolymer: EMAA Surlyn 8527, DuPont, USA; Maleic anhydride grafted polyethylene: 1053H, Dow Chemical, USA; Talc: average particle size 400 mesh.

[0028] Example 1 A method for preparing an aging-resistant insulated power cable comprises the following steps: S1. Extruding the insulation layer material on the outside of the cable core to obtain a semi-finished cable; S2, after uniformly mixing 60 parts of polyethylene, 10 parts of polypropylene, 30 parts of ethylene-vinyl acetate copolymer, 3 parts of peroxide crosslinking agent DCP, 1 part of antioxidant 1010, 10 parts of talc powder, and 4 parts of maleic anhydride grafted polyethylene, extruding the mixture on the outside of the semi-finished cable to obtain an aging-resistant insulated power cable; The ethylene-vinyl acetate copolymer is composed of DuPont Elvax 3172 (vinyl acetate content 18.0%, melt index 2.5 g / 10 min) and DuPont Elvax 3174 (vinyl acetate content 18.0%, melt index 8.0 g / 10 min) in a mass ratio of 3:1.

[0029] Example 2 A method for preparing an aging-resistant insulated power cable comprises the following steps: S1. Extruding the insulation layer material on the outside of the cable core to obtain a semi-finished cable; S2, after uniformly mixing 70 parts of polyethylene, 20 parts of polypropylene, 40 parts of ethylene-vinyl acetate copolymer, 6 parts of peroxide crosslinking agent DCP, 3 parts of antioxidant 1010, 15 parts of talc powder, and 6 parts of maleic anhydride grafted polyethylene, extruding the mixture on the outside of the semi-finished cable to obtain an aging-resistant insulated power cable; The ethylene-vinyl acetate copolymer is composed of DuPont Elvax 3172 (vinyl acetate content 18.0%, melt index 2.5 g / 10 min) and DuPont Elvax 3174 (vinyl acetate content 18.0%, melt index 8.0 g / 10 min) in a mass ratio of 3:1.

[0030] Example 3 Compared with Example 1, the only difference in this example is that DuPont Elvax 3172 (vinyl acetate content 18.0%, melt index 2.5 g / 10 min) is replaced with an equal amount of Elvax 3169Z (vinyl acetate content 18%, melt index 1.5 g / 10 min).

[0031] Example 4 Compared with Example 1, the only difference of this example is that DuPont Elvax 3174 (vinyl acetate content 18.0%, melt index 8.0 g / 10 min) is replaced with an equal amount of DuPont Elvax 3176 (vinyl acetate content 18.0%, melt index 30.0 g / 10 min).

[0032] Example 5 Compared with Example 1, the only difference of this embodiment is that the inorganic filler of this embodiment is a composite inorganic filler. The preparation method of the composite inorganic filler comprises the following steps: adding 2.0 g of 2,4-dichloro-5-aminophenol to 300 mL of anhydrous ethanol and dispersing the mixture evenly, adding 40 g of talc powder and modifying the mixture at 40° C. for 2 h, and drying the mixture to obtain a composite inorganic filler.

[0033] Example 6 Compared with Example 1, the only difference of this embodiment is that the inorganic filler of this embodiment is a composite inorganic filler. The preparation method of the composite inorganic filler comprises the following steps: adding 2.0 g of cyclohexyl-1,4-dimethanol monovinyl ether to 300 mL of anhydrous ethanol and dispersing the mixture uniformly, adding 40 g of talc powder and modifying the mixture at 40° C. for 2 h, and drying the mixture to obtain a composite inorganic filler.

[0034] Example 7 Compared with Example 1, the only difference of this embodiment is that the inorganic filler of this embodiment is a composite inorganic filler. The preparation method of the composite inorganic filler comprises the following steps: adding 1.0 g of cyclohexyl-1,4-dimethanol monovinyl ether and 1.0 g of 2,4-dichloro-5-aminophenol to 300 mL of anhydrous ethanol and dispersing them evenly, adding 40 g of talc powder and modifying them at 40° C. for 2 h, and drying to obtain a composite inorganic filler.

[0035] Example 8 Compared with Example 1, the only difference of this embodiment is that the inorganic filler of this embodiment is a composite inorganic filler. The preparation method of the composite inorganic filler comprises the following steps: adding 1.0 g of 2,4-dichloro-5-aminophenol to 300 mL of anhydrous ethanol and dispersing the mixture evenly, adding 40 g of talc and modifying the mixture at 40° C. for 1 hour, then adding 1.0 g of cyclohexyl-1,4-dimethanol monovinyl ether and continuing to modify the mixture at 40° C. for 1 hour, and drying the mixture to obtain a composite inorganic filler.

[0036] Example 9 Compared with Example 1, the only difference of this embodiment is that the inorganic filler of this embodiment is a composite inorganic filler. The preparation method of the composite inorganic filler comprises the following steps: adding 1.0 g of cyclohexyl-1,4-dimethanol monovinyl ether to 300 mL of anhydrous ethanol and dispersing the mixture uniformly, adding 40 g of talc and modifying the mixture at 40° C. for 1 hour, then adding 1.0 g of 2,4-dichloro-5-aminophenol and continuing to modify the mixture at 40° C. for 1 hour, and drying the mixture to obtain a composite inorganic filler.

[0037] Example 10 Compared with Example 8, the only difference in this example is that 2,4-dichloro-5-aminophenol is replaced by an equal amount of 3,5-dichloro-4-hydroxybenzaldehyde.

[0038] Comparative Example 1 Compared with Example 1, the only difference in this comparative example is that the ethylene-vinyl acetate copolymer is only DuPont Elvax 3172 (vinyl acetate content 18.0%, melt index 2.5 g / 10 min).

[0039] Comparative Example 2 Compared with Example 1, the only difference in this comparative example is that the ethylene-vinyl acetate copolymer is only DuPont Elvax 3174 (vinyl acetate content 18.0%, melt index 8.0 g / 10 min).

[0040] Experimental example The elongation at break and aging resistance of the cable sheath layers in Examples 1 to 10 and Comparative Examples 1 to 2 were measured as follows: (1) Aging resistance: The tensile strength before and after thermal aging shall be tested in accordance with the method specified in GB / T2951.12-2008 "General test methods for insulation and sheath materials of electric and optical cables Part 12: General test methods. Thermal aging test methods". The test conditions are: 100°C, 72h; (2) Elongation at break: The elongation at break shall be tested in accordance with the method specified in GB / T2951.11-2008 "General test methods for insulation and sheathing materials of electric and optical cables Part 11: General test methods - Determination of thickness and dimensions - Mechanical properties test"; The measurement results are shown in Tables 1 and 2 below.

[0041] Table 1 Test results of elongation at break of the sheath layer in Examples 1 to 4 and Comparative Examples 1 to 2

[0042] As can be seen from Table 1, the elongation at break of the cable sheath layer in Examples 1 to 4 of the present invention is higher than that in Comparative Examples 1 to 2, indicating that the cable sheath layer of the present invention has a higher elongation at break.

[0043] Table 2 Test results of aging resistance of the sheath layer in Examples 1 and 5 to 10

[0044] It can be seen from Table 2 that the addition of the composite filler in the embodiment of the present invention can not only improve the aging resistance of the cable sheath layer, but also improve the tensile strength of the cable sheath layer.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An aging-resistant insulated power cable, characterized in that: The cable comprises a cable core, an insulation layer and a sheath layer, wherein the sheath layer comprises the following raw materials in parts by weight: 60 to 70 parts of polyethylene, 10 to 20 parts of polypropylene, 30 to 40 parts of ethylene-vinyl acetate copolymer, 3 to 6 parts of a cross-linking agent, 1 to 3 parts of an antioxidant, 10 to 15 parts of an inorganic filler and 4 to 6 parts of a compatibilizer; the ethylene-vinyl acetate copolymer consists of a first ethylene-vinyl acetate copolymer and a second ethylene-vinyl acetate copolymer, the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer have the same vinyl acetate content and different melt indexes; the vinyl acetate content of the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer are both 18.0%.

2. The aging-resistant insulated power cable according to claim 1, characterized in that: The melt index of the first ethylene-vinyl acetate copolymer and the second ethylene-vinyl acetate copolymer are each independently 1.5 to 30 g / 10 min.

3. The aging-resistant insulated power cable according to claim 1, characterized in that: The melt index of the first ethylene-vinyl acetate copolymer is 2.5 g / 10 min, and the melt index of the second ethylene-vinyl acetate copolymer is 8.0 g / 10 min.

4. The aging-resistant insulated power cable according to claim 1, characterized in that: The mass ratio of the first ethylene-vinyl acetate copolymer to the second ethylene-vinyl acetate copolymer is 2-5:

1.

5. The aging-resistant insulated power cable according to claim 1, characterized in that: The inorganic filler is a composite inorganic filler, and the raw materials of the composite inorganic filler include talc powder and a hydroxyl-containing compound; the hydroxyl-containing compound includes a first hydroxyl-containing compound and a second hydroxyl-containing compound, the first hydroxyl-containing compound includes one of 3,5-dichloro-4-hydroxybenzaldehyde and 2,4-dichloro-5-aminophenol, and the second hydroxyl-containing compound is cyclohexyl-1,4-dimethanol monovinyl ether.

6. The aging-resistant insulated power cable according to claim 5, characterized in that: The preparation method of the composite inorganic filler comprises the following steps: adding a hydroxyl-containing compound into a solvent and dispersing the mixture uniformly, adding talcum powder, mixing the mixture, and drying the mixture to obtain the composite inorganic filler.

7. The aging-resistant insulated power cable according to claim 5, characterized in that: The hydroxyl-containing compound accounts for 4% to 6% of the mass of talc.

8. The aging-resistant insulated power cable according to claim 1, characterized in that: The crosslinking agent is a peroxide crosslinking agent.

9. The aging-resistant insulated power cable according to claim 1, characterized in that: The antioxidant includes one or more of phosphite antioxidants, amine antioxidants, and phenolic antioxidants.

10. The aging-resistant insulated power cable according to claim 1, characterized in that: The compatibilizer includes maleic anhydride grafted polyethylene.

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