A highly flame-retardant power cable and its preparation method

Abstract

The present invention relates to the technical field of power cables and provides a highly flame-retardant power cable and a method for preparing the same. The highly flame-retardant power cable comprises a conductor, an insulation layer, and a sheath layer, arranged sequentially from the inside out. The sheath layer comprises the following components by weight: 50-60 parts of polyethylene, 60-70 parts of ethylene-vinyl acetate copolymer, 20-25 parts of methyl vinyl silicone rubber, 8-10 parts of a plastic alloy, 50-60 parts of a flame suppressant, 2-3 parts of a lubricant, 1-1.5 parts of an antioxidant, and 1-3 parts of a vulcanizing agent. The plastic alloy comprises PC / ABS and PC / PBT, with different types of flame retardants added to the PC / ABS and PC / PBT. The above technical solution solves the problem of poor flame retardancy in power cables in the related art.

Description

Technical Field

[0001] The present invention relates to the technical field of power cables, and in particular to a highly flame-retardant power cable and a preparation method thereof. Background Art

[0002] Power cables are cables used to transmit and distribute electrical energy. They have a wide range of applications. In urban construction, they are used in underground transmission networks to ensure stable and secure power supply and prevent overhead lines from encroaching on urban landscapes and space. In the industrial sector, they provide power to production equipment in industrial and mining enterprises, meeting their high-power, high-reliability electricity needs. In energy transmission, they connect power stations with substations, and substations with end users, enabling efficient long-distance transmission of electrical energy.

[0003] Flame-retardant power cables are currently widely used in various construction fields. However, the flame retardancy of some power cables remains problematic. Cables with poor flame retardancy can easily ignite when exposed to ignition sources such as open flames or high temperatures, becoming a starting point for fires. For example, in densely cabled areas like substations, distribution rooms, and cable tunnels, once a fire breaks out, the flames of poorly flame-retardant cables can spread rapidly throughout the cable cluster, quickly spreading to a large area and making firefighting extremely difficult. Furthermore, when cables burn, their insulation performance rapidly degrades, leading to electrical incidents such as phase-to-phase short circuits and ground faults. These faults can disrupt power supply, impacting industrial production, residents' lives, and other aspects, resulting in significant socioeconomic losses. For critical power systems such as hospitals, airports, and communications hubs, power outages can trigger a range of serious consequences.

[0004] Therefore, it is necessary to develop a power cable with high flame retardant properties. Summary of the Invention

[0005] The present invention provides a highly flame-retardant power cable and a preparation method thereof, which solves the problem of poor flame-retardant performance of power cables in the related art.

[0006] The technical solution of the present invention is as follows: The present invention proposes a highly flame-retardant power cable, comprising a conductor, an insulation layer and a sheath layer arranged in sequence from the inside to the outside, wherein the sheath layer comprises the following component raw materials in parts by weight: 50-60 parts of polyethylene, 60-70 parts of ethylene-vinyl acetate copolymer, 20-25 parts of methyl vinyl silicone rubber, 8-10 parts of plastic alloy, 50-60 parts of flame retardant, 2-3 parts of lubricant, 1-1.5 parts of antioxidant, and 1-3 parts of vulcanizer; the plastic alloy is composed of PC / ABS and PC / PBT, and the types of flame retardants added to the PC / ABS and the PC / PBT are different.

[0007] As a further technical solution, the conductor is made of copper.

[0008] Copper has excellent electrical conductivity, and its electrical conductivity ranks among the highest among common metals. When copper is used as the conductor material, high-flame-retardant power cables can significantly reduce resistance during power transmission, thereby reducing power loss in the transmission line. This not only improves the efficiency of power transmission and reduces energy waste, but also effectively avoids cable heating due to excessive resistance, thereby improving the stability and reliability of the entire power system. Copper also has good flexibility and ductility, which makes copper conductors easier to process and bend during the cable manufacturing process. During the actual installation process, construction workers can more conveniently lay cables in various complex environments and spaces without causing installation difficulties or damage due to the conductor being too hard.

[0009] As a further technical solution, the insulating layer is a cross-linked polyethylene insulating layer.

[0010] In the present invention, the insulation layer adopts a cross-linked polyethylene insulation layer. The cross-linked polyethylene has extremely high electrical insulation strength and can effectively prevent the leakage of current and the occurrence of flashover. In a high voltage environment, it can reliably isolate the conductor from the outside world to ensure the stable transmission of electricity. The cross-linked polyethylene uses a cross-linking process to transform the molecular structure from linear to mesh, which greatly improves its heat resistance. During the operation of the cable, a certain amount of heat is generated due to the passage of current. The cross-linked polyethylene insulation layer can maintain stable performance at higher temperatures and is not easy to soften or deform, so that the cable can operate normally within a wider temperature range and adapt to different environmental conditions.

[0011] As a further technical solution, the model of the PC / ABS is CE3210, and the flame retardant is a non-chlorine and non-bromine flame retardant; the model of the PC / PBT is V3900WX, and the flame retardant is a halogen flame retardant.

[0012] In the present invention, PC / ABS with model CE3210 is used in combination with a non-chlorine and non-bromine flame retardant, and PC / PBT with model V3900WX is used in combination with a halogen flame retardant. The unique flame retardant mechanisms of different flame retardants are utilized. During the combustion process, the non-chlorine and non-bromine flame retardant inhibits the combustion reaction by absorbing heat and forming carbon. The formed carbon layer can effectively isolate heat and oxygen and slow down the spread of flames. The halogen flame retardant captures the free radicals generated during the combustion process, interrupts the combustion chain reaction, and quickly suppresses the flame. The combination of two different types of flame retardants and corresponding materials achieves complementary advantages and significantly improves the overall flame retardant performance of the cable sheath layer.

[0013] As a further technical solution, the mass ratio of the PC / ABS to the PC / PBT is 1:1-5, for example, 1:1, 1:2, 1:3, 1:4, 1:5, preferably 1:2-3.

[0014] In the present invention, when the mass ratio of PC / ABS and PC / PBT is 1:2-3, a more effective synergistic effect can be formed, which is of great significance for the performance optimization, environmental protection requirements and cost control of the high flame retardant power cable sheath layer.

[0015] As a further technical solution, the flame suppressant is a hydroxyphenyl sulfide compound composite aluminum hydroxide, and the raw materials of the hydroxyphenyl sulfide compound composite aluminum hydroxide include a hydroxyphenyl sulfide compound and aluminum hydroxide in a mass ratio of 2 to 3:20.

[0016] In the present invention, aluminum hydroxide itself is a commonly used inorganic flame retardant, which achieves flame retardancy by absorbing heat through thermal decomposition and releasing crystal water to dilute oxygen. In order to achieve sufficient flame retardant performance, it is often necessary to add a large amount of aluminum hydroxide to the polymer material. A large amount of aluminum hydroxide filling will destroy the continuity and uniformity of the polymer material, resulting in a decrease in the mechanical properties of the material, making the cable sheath layer prone to rupture and deformation when subjected to external forces, thereby affecting the service life and reliability of the cable; unmodified aluminum hydroxide has poor compatibility with most organic polymer materials. The reason is that aluminum hydroxide is an inorganic material with strong surface polarity, while organic polymer materials are usually non-polar or weakly polar, and the interfacial bonding force between the two is weak, which leads to uneven dispersion of aluminum hydroxide in the polymer matrix and easy agglomeration. The agglomerated aluminum hydroxide will not only reduce the flame retardant effect, but also further reduce the mechanical properties and processing performance of the material.

[0017] As a further technical solution, the hydroxyphenyl sulfide compound includes one or both of 2-hydroxyphenyl sulfide and 4,4'-dihydroxydiphenyl disulfide, preferably 4,4'-dihydroxydiphenyl disulfide.

[0018] In the present invention, a hydroxyphenyl sulfide compound is used to compound with aluminum hydroxide. The hydroxyphenyl sulfide compound contains active functional groups that can form an interaction force with hydroxyl groups on the surface of the aluminum hydroxide, thereby improving the surface properties of the aluminum hydroxide, reducing its surface polarity, and improving its compatibility with the polymer matrix, thereby significantly enhancing the interfacial bonding force between the aluminum hydroxide and the polymer matrix. The uniformly dispersed aluminum hydroxide is equivalent to forming a uniformly distributed reinforcing phase in the polymer matrix, thereby enhancing the structural stability of the material and further improving the mechanical strength of the material.

[0019] As a further technical solution, the preparation process of the hydroxyphenyl sulfide compound composite aluminum hydroxide includes the following steps: dispersing the hydroxyphenyl sulfide compound in anhydrous ethanol, adding aluminum hydroxide, mixing and drying to obtain the hydroxyphenyl sulfide compound composite aluminum hydroxide.

[0020] As a further technical solution, the mass ratio of the anhydrous ethanol to the aluminum hydroxide is 2 to 5:1, for example, it can be 2:1, 3:1, 4:1, 5:1, and preferably 3:1.

[0021] As a further technical solution, the mixing time is 2 hours.

[0022] As a further technical solution, the lubricant includes one or both of calcium stearate and zinc stearate.

[0023] In the present invention, the addition of a lubricant can effectively reduce the friction between the raw materials of each component during the production process of the cable sheath layer. During the extrusion molding process, the lubricant can reduce the adhesion between the material and the processing equipment, making the material easier to flow, improving the extrusion speed and production efficiency, while ensuring the thickness uniformity and surface quality of the cable sheath layer, and reducing the occurrence of defects such as surface roughness and scratches; at the same time, the presence of the lubricant can also reduce the mutual entanglement and friction between polymer chains, so that the polymer chains can move and orient more freely when subjected to external forces, thereby improving the flexibility and impact resistance of the material.

[0024] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 1035.

[0025] In the present invention, the addition of an antioxidant can effectively inhibit the oxidation process of the cable material and extend the service life of the cable. During the operation of the cable, since the current passes through the conductor to generate heat, the cable sheath layer and other components will be in a relatively high temperature environment. The antioxidant can remain stable at high temperatures and exert an antioxidant effect to prevent the performance of the polymer material from being degraded due to thermal oxidation, ensuring that the cable can still operate reliably in a high temperature environment and reducing the risk of cable failure caused by thermal oxidation.

[0026] As a further technical solution, the vulcanizing agent includes one or both of dibenzoyl peroxide and tert-butyl perbenzoate.

[0027] In the present invention, the cable sheath layer contains methyl vinyl silicone rubber materials, and the vulcanizing agent can trigger a cross-linking reaction between the rubber molecular chains, forming chemical bonds between the molecular chains, thereby transforming the linear rubber molecules into a three-dimensional network structure. This cross-linking structure gives the rubber better physical properties, thermal stability and chemical stability.

[0028] The present invention also provides a method for preparing a highly flame-retardant power cable, which comprises the following steps:

[0029] S1. After extruding an insulating layer outside the conductor, a semi-finished product is obtained;

[0030] S2. Evenly mix the raw materials for the sheath layer, extrude the raw materials onto the semi-finished product, and vulcanize the semi-finished product to obtain a highly flame-retardant power cable.

[0031] As a further technical solution, the mixing time is 20-30 minutes, the vulcanization time is 10-15 minutes, and the vulcanization temperature is 170°C.

[0032] The working principle and beneficial effects of the present invention are:

[0033] In the present invention, polyethylene, ethylene-vinyl acetate copolymer and methyl vinyl silicone rubber cooperate with each other to give the cable good flexibility and mechanical properties, ensuring that it can be stably installed and used in complex environments and is not easily damaged by external forces. The plastic alloy is composed of PC / ABS and PC / PBT, and different types of flame retardants are added to the two. Different flame retardants play a role in different plastic alloy components. When combined with a flame retardant, the combustion reaction can be better suppressed. When encountering a fire source, the spread of flames can be effectively prevented, reducing the risk of cable combustion when a fire occurs. Combined with other auxiliary components such as lubricants, antioxidants, vulcanizers, etc., not only the flame retardant effect of the cable is enhanced, but also to a certain extent, the cable can be prevented from aging, its service life can be extended, and the economic cost and manpower investment caused by frequent cable replacement can be reduced. DETAILED DESCRIPTION

[0034] 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.

[0035] In the following examples and comparative examples:

[0036] Polyethylene: Model 2102TN00;

[0037] Ethylene-vinyl acetate copolymer: model 420;

[0038] Methyl vinyl silicone rubber: Model 110-2;

[0039] PC / ABS: Model CE3210, flame retardant is non-chlorine and non-bromine flame retardant;

[0040] PC / PBT: Model V3900WX, flame retardant is halogen flame retardant;

[0041] Aluminum hydroxide: average particle size is 800 mesh.

[0042] Example 1

[0043] A method for preparing a highly flame-retardant power cable comprises the following steps:

[0044] S1. After extruding a cross-linked polyethylene insulation layer on the outside of the copper conductor, a semi-finished product is obtained;

[0045] S2. Mix 50 parts of polyethylene, 60 parts of ethylene-vinyl acetate copolymer, 20 parts of methyl vinyl silicone rubber, 8 parts of plastic alloy, 50 parts of flame retardant, 2 parts of calcium stearate, 1 part of antioxidant 1010, and 1 part of dibenzoyl peroxide for 20 minutes, extrude it onto the outside of the semi-finished product, and vulcanize it at 170°C for 10 minutes to obtain a highly flame-retardant power cable; the plastic alloy is composed of PC / ABS and PC / PBT in a mass ratio of 1:2, and the flame retardant is aluminum hydroxide.

[0046] Example 2

[0047] A method for preparing a highly flame-retardant power cable comprises the following steps:

[0048] S1. After extruding a cross-linked polyethylene insulation layer on the outside of the copper conductor, a semi-finished product is obtained;

[0049] S2. Mix 55 parts of polyethylene, 65 parts of ethylene-vinyl acetate copolymer, 22 parts of methyl vinyl silicone rubber, 9 parts of plastic alloy, 55 parts of flame retardant, 2.5 parts of calcium stearate, 1.2 parts of antioxidant 168, and 2 parts of dibenzoyl peroxide for 25 minutes, extrude the mixture onto the outside of the semi-finished product, and vulcanize it at 170°C for 12 minutes to obtain a highly flame-retardant power cable; the plastic alloy is composed of PC / ABS and PC / PBT in a mass ratio of 1:2, and the flame retardant is aluminum hydroxide.

[0050] Example 3

[0051] A method for preparing a highly flame-retardant power cable comprises the following steps:

[0052] S1. After extruding a cross-linked polyethylene insulation layer on the outside of the copper conductor, a semi-finished product is obtained;

[0053] S2. Mix 60 parts of polyethylene, 70 parts of ethylene-vinyl acetate copolymer, 25 parts of methyl vinyl silicone rubber, 10 parts of plastic alloy, 60 parts of flame retardant, 3 parts of zinc stearate, 1.5 parts of antioxidant 1035, and 3 parts of tert-butyl perbenzoate for 30 minutes, extrude the mixture onto the semi-finished product, and vulcanize at 170°C for 15 minutes to obtain a highly flame-retardant power cable; the plastic alloy is composed of PC / ABS and PC / PBT in a mass ratio of 1:2, and the flame retardant is aluminum hydroxide.

[0054] Example 4

[0055] Compared with Example 1, the difference of Example 4 is that the plastic alloy consists of PC / ABS and PC / PBT in a mass ratio of 1:3.

[0056] Example 5

[0057] The preparation process of the flame retardant includes the following steps: dispersing 6 parts of 2-hydroxyphenylbenzene sulfide in 180 parts of anhydrous ethanol, adding 60 parts of aluminum hydroxide, mixing for 2 hours and then drying to obtain a hydroxyphenyl sulfide compound composite aluminum hydroxide, which is the flame retardant;

[0058] Compared with Example 4, the difference of Example 5 is that the flame suppressant is replaced with an equal amount of the flame suppressant obtained by the above preparation method.

[0059] Example 6

[0060] Compared with Example 5, the difference of Example 6 is that the added amount of 2-hydroxyphenylbenzene sulfide is 9 parts.

[0061] Example 7

[0062] Compared with Example 6, Example 7 is different in that 2-hydroxyphenylbenzene sulfide is replaced by an equal amount of 4,4'-dihydroxydiphenyl disulfide.

[0063] Comparative Example 1

[0064] Compared with Example 1, the difference in Comparative Example 1 is that the plastic alloy is PC / ABS.

[0065] Comparative Example 2

[0066] Compared with Example 1, the difference in Comparative Example 2 is that the plastic alloy is PC / PBT.

[0067] Experimental Example 1

[0068] The sheath layers of the power cables prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to oxygen index tests according to the test method specified in GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test"; wherein the sample shape is a Type IV sample with a sample size of 100 mm × 6 mm × 3 mm, and the ignition method is Method A.

[0069] The test results are shown in Table 1:

[0070] Table 1 Performance test results of power cables prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0071]

[0072] It can be seen from Table 1 that when PC / ABS and PC / PBT are added at the same time, the flame retardant performance of the power cable can be improved.

[0073] Experimental Example 2

[0074] The tensile strength of the power cables prepared in Examples 4 to 7 was tested according to the test method specified in GB / T 2951.11-2008 "General test methods for insulation and sheathing materials of electric and optical cables - Part 11: General test methods - Thickness and dimensional measurement - Mechanical properties test". The sample preparation was as follows: the sheath was cut along the cable axis, and a narrow strip was cut to make a small dumbbell specimen with a thickness of 2.0 mm, which was the test sample.

[0075] The test results are shown in Table 2:

[0076] Table 2 Performance test results of power cables prepared in Examples 4 to 7

[0077]

[0078] It can be seen from Table 2 that the addition of hydroxyphenyl sulfide compound composite aluminum hydroxide can improve the mechanical strength of the power cable.

[0079] 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. A highly flame-retardant power cable, characterized in that: The invention comprises a conductor, an insulating layer and a sheath layer arranged in sequence from the inside out. The sheath layer comprises the following raw materials by weight: 50-60 parts of polyethylene, 60-70 parts of ethylene-vinyl acetate copolymer, 20-25 parts of methyl vinyl silicone rubber, 8-10 parts of plastic alloy, 50-60 parts of flame retardant, 2-3 parts of lubricant, 1-1.5 parts of antioxidant, and 1-3 parts of vulcanizing agent. The plastic alloy is composed of PC / ABS and PC / PBT, and the PC / ABS and PC / PBT are added with different types of flame retardants. The model of the PC / ABS is CE3210, and the flame retardant is a non-chlorine and non-bromine flame retardant; the model of the PC / PBT is V3900WX, and the flame retardant is a halogen flame retardant; The flame suppressant is a hydroxyphenyl sulfide compound composite aluminum hydroxide, and the raw materials of the hydroxyphenyl sulfide compound composite aluminum hydroxide include a hydroxyphenyl sulfide compound and aluminum hydroxide in a mass ratio of 2 to 3:20; The hydroxyphenyl sulfide compound includes one or both of 2-hydroxyphenyl sulfide and 4,4'-dihydroxydiphenyl disulfide.

2. A highly flame-retardant power cable according to claim 1, characterized in that: The material of the conductor is copper.

3. A highly flame-retardant power cable according to claim 1, characterized in that: The insulating layer is a cross-linked polyethylene insulating layer.

4. A highly flame-retardant power cable according to claim 1, characterized in that: The mass ratio of the PC / ABS to the PC / PBT is 1:1-5.

5. The highly flame-retardant power cable according to claim 1, characterized in that: The lubricant includes one or both of calcium stearate and zinc stearate.

6. A highly flame-retardant power cable according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 1035; The vulcanizing agent includes one or both of dibenzoyl peroxide and tert-butyl perbenzoate.

7. A method for preparing a highly flame-retardant power cable, for preparing a highly flame-retardant power cable according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. After extruding an insulating layer outside the conductor, a semi-finished product is obtained; S2. Evenly mix the raw materials for the sheath layer, extrude the raw materials onto the semi-finished product, and vulcanize the semi-finished product to obtain a highly flame-retardant power cable.

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