Power cable for low-voltage electrical equipment and preparation method thereof

Abstract

The invention discloses a power cable for low-voltage electrical equipment and a preparation method of the power cable, and relates to the technical field of power cables. The invention provides a power cable for low-voltage electrical equipment. The power cable at least comprises a conductor core wire, an insulating layer and a sheath layer from inside to outside, wherein the conductor core wire is coated with the insulating layer, and the insulating layer is extruded with the sheath layer; the sheath layer at least comprises the following raw materials in parts by mass: 100 parts of polyvinyl chloride resin; 5-8 parts of chlorinated polyethylene; 35 to 45 parts of a polyester plasticizer; 25-35 parts of a modified composite flame retardant; 0.5 to 1.5 parts of a modified dibenzoylmethane / choline compound; 2-4 parts of a calcium / zinc composite heat stabilizer; 10-20 parts of an inorganic filler; 0.1 to 0.3 part of an antioxidant; and 0.8-2 parts of a lubricant. The prepared power cable for the low-voltage electrical equipment has excellent long-acting halogen-free flame retardance, extremely low smoke density, lasting antibacterial and mildew-proof properties and good mechanical properties and processing stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power cable, in particular to a low-voltage electrical equipment power cable and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern industry and technology, the demand for power transmission and signal transmission is increasing, and the performance and safety of cable as an important carrier of power and information transmission are directly related to the stable operation of the whole system. The cable is a kind of conductor material used to transmit power or signal current and signal voltage, which can be divided into high-voltage cable and low-voltage cable according to voltage. The low-voltage cable line is composed of three parts: core, insulation layer and protective layer, which has the advantages of reliable operation, no need to erect electric poles, no occupation of ground, no obstruction to view, less affected by the outside world, etc., and is widely used in low-voltage power distribution system; the outermost protective layer is used to protect the insulation layer from damage by external force and water intrusion during transportation, laying and use, and polyvinyl chloride sheath is often used as the outermost protective layer.

[0003] Firstly, low-voltage cable often faces complex environmental conditions in actual application. In the occasion where high mechanical protection is required, the cable is frequently subjected to external forces such as extrusion, friction and impact. The traditional halogen-containing cable is prone to aging, cracking and even failure under complex environmental conditions. In addition, the cable has the defects of low strength and poor impact resistance during use, which shortens the service life of the cable and affects the normal operation of the whole system. At the same time, the traditional PVC material releases a large amount of toxic gas such as hydrogen chloride when burning, which can cause serious harm to human health and corrosion to the surrounding equipment and environment. In addition, the burning of halogen-containing materials also produces a large amount of smoke, which reduces the visibility of the fire scene and increases the difficulty of rescue.

[0004] Secondly, when the low-voltage cable is placed in a humid or long-term water environment, water will penetrate and adsorb inside the PVC material and the gap between the cores. This not only causes a significant decrease in insulation resistance, resulting in a risk of electric leakage, but also accelerates the hydrolysis and precipitation of plasticizers, making the material hard and brittle and losing flexibility, ultimately shortening the service life of the cable. In hot and humid conditions, it is easy to promote the growth and reproduction of mold, and it is easy to spread the mold growing and reproducing in the soil to the surface of the cable, causing the mechanical properties of the PVC protective layer to be gradually damaged, gradually making the PVC protective layer thin and brittle, not only the weight gradually decreases, the low temperature elongation greatly decreases, shortens the service life of the PVC protective layer.

[0005] Therefore, it is necessary to modify the cable sheath material by improving the performance of the sheath material to improve the comprehensive performance of the cable such as antibacterial, mildew resistance, flame retardance and moisture resistance. SUMMARY

[0006] The present application aims to provide a power cable for low-voltage electrical equipment and a preparation method thereof, and solve the following technical problems: The existing sheath material for power cables has the problems of poor moisture resistance, poor antibacterial and mildew resistance, and poor flame retardance.

[0007] The purpose of the present application can be achieved by the following technical solutions: A power cable for low-voltage electrical equipment, comprising at least a conductor core, an insulation layer wrapped outside the conductor core, and a sheath layer extruded outside the insulation layer from inside to outside; The sheath layer comprises at least the following raw materials by mass fraction: 100 parts of polyvinyl chloride resin, 5-8 parts of chlorinated polyethylene, 35-45 parts of polyester plasticizer, 25-35 parts of modified composite flame retardant, 0.5-1.5 parts of modified dibenzoylmethane / choline compound, 2-4 parts of calcium / zinc composite heat stabilizer, 10-20 parts of inorganic filler, 0.1-0.3 parts of antioxidant, and 0.8-2 parts of lubricant.

[0008] As a further scheme of the present application, the preparation method of the modified composite flame retardant comprises the following steps: Melamine is added to distilled water, and after adjusting the pH to 8-8.5, formaldehyde solution is added dropwise, and after reaction, pyrazophosphoric acid solution is added, and after reaction, washing and drying, an intumescent flame retardant is obtained; Ammonium polyphosphate is dispersed in deionized water, and the hydrolyzate of gamma-aminopropyl triethoxysilane is added, and after reaction, washing and drying, modified ammonium polyphosphate is obtained; The intumescent flame retardant and the modified ammonium polyphosphate are mixed and dispersed in anhydrous ethanol, the pH is adjusted to 6-6.5, a dimethylacetamide solution of polyimide resin is added, and spray drying is performed to obtain a composite modified flame retardant.

[0009] As a further scheme of the present application, the mass fraction of the formaldehyde solution is 35-40%, and the mass ratio of the melamine, the formaldehyde and the pyrazophosphoric acid is 12-13:5-6:27-28.

[0010] As a further scheme of the present application, the mass ratio of the ammonium polyphosphate and the gamma-aminopropyl triethoxysilane is 1:0.01-0.02.

[0011] As a further scheme of the present application, the mass ratio of the intumescent flame retardant and the modified ammonium polyphosphate is 1-2:1, and the mass ratio of the total weight of the intumescent flame retardant and the modified ammonium polyphosphate to the polyimide resin is 1:0.15-0.3.

[0012] As a further scheme of the present application: the preparation method of the modified dibenzoylmethane / choline compound comprises the following steps: Dissolve dibenzoylmethane in ethanol, adjust the pH to 6-6.5, add choline after reaction, and obtain dibenzoylmethane / choline compound; Mix the dibenzoylmethane / choline compound and N,N-dimethylformamide, add N,N-dimethylformamide solution of octadecyl isocyanate under nitrogen protection, wash and dry after reaction, and obtain modified dibenzoylmethane / choline compound.

[0013] As a further scheme of the present application: the molar ratio of the dibenzoylmethane and the choline is 1:1, and the mass ratio of the dibenzoylmethane / choline compound and the octadecyl isocyanate is 1:0.8-1.2.

[0014] As a further scheme of the present application: the inorganic filler is one or a mixture of more of aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, clay, mica or kaolin, the lubricant is one or a mixture of more of zinc stearate, white wax, stearic acid and polyethylene wax, and the antioxidant is one or a mixture of more of phenolic antioxidant, phosphite antioxidant or amine antioxidant.

[0015] A preparation method of the power cable for low-voltage electrical equipment according to any one of the above, at least comprising the following steps: Form an insulation layer by extruding insulation layer material on the surface of the conductor core through an extruder, form a sheath layer by extruding sheath layer material outside the insulation layer through an extruder, and obtain the power cable for low-voltage electrical equipment after cooling and setting.

[0016] As a further scheme of the present application: the conductor core is twisted by a plurality of thin copper wires, and the material of the insulation layer is thermoplastic polyester elastomer.

[0017] The present application has the following beneficial effects: The low-voltage electrical equipment power cable provided by the application comprises, from inside to outside, a conductor core, an insulation layer and a sheath layer, the conductor core is twisted by a plurality of thin copper wires, the material of the insulation layer is thermoplastic polyester elastomer, the insulation layer plays a basic function of a wire and cable, that is, a basic ability of transmitting information, and the sheath layer plays a function of protecting the internal structure. The sheath layer takes polyvinyl chloride as a base material, adds chlorinated polyethylene to improve impact resistance and flexibility, and adds a polyester plasticizer to balance softness and migration resistance, so that the prepared sheath layer has good mechanical properties and processing properties. The sheath layer of the application further comprises a modified composite flame retardant and a modified dibenzoylmethane / choline compound. The modified composite flame retardant not only retains the low-smoke property of the intumescent flame retardant, but also enhances the compatibility of the flame retardant and the resin base material through the polyimide resin, thereby avoiding the mechanical property decline caused by the traditional flame retardant. The modified dibenzoylmethane / choline compound has anti-aging and lubricating functions, and cooperates with calcium / zinc heat stabilizer to improve the weather resistance and processing stability of the material. The low-voltage electrical equipment power cable prepared by the application meets the requirements of mechanical protection, flame retardation, softness, moisture resistance and the like, and is especially suitable for low-voltage electrical equipment power supply scenes in humid environments, frequent bending and mechanical vibration.

[0018] The modified composite flame retardant prepared in the application is a polyimide resin coated intumescent flame retardant and ammonium polyphosphate. The prepared intumescent flame retardant is a macromolecular intumescent flame retardant integrating acid source, gas source and carbon source by reaction of melamine, formaldehyde and piperazine pyrophosphate. The ammonium polyphosphate is surface treated by a silane coupling agent to introduce an amino functional group. The two kinds of flame retardants are compounded, the amino group on the modified ammonium polyphosphate reacts with the hydroxymethyl group on the intumescent flame retardant, so that the intumescent flame retardant and the ammonium polyphosphate are covalently connected, solving the compatibility problem. In the process of processing and use, the two will not migrate and separate again, and finally coated with a high-performance polymer polyimide resin. The ammonium polyphosphate can produce strong dehydrating polyphosphoric acid when heated, which cooperates with the carbon component of the intumescent flame retardant to form a more dense and firm intumescent carbon layer, which can quickly and efficiently complete the intumescent flame retardation reaction during combustion, and has high flame retardation efficiency. The polyimide resin coating makes the modified composite flame retardant have excellent water resistance and durability. The polyimide resin shell layer completely isolates the water-sensitive flame retardant from the external environment, completely solves the problems of easy hydrolysis and easy migration of inorganic flame retardants, and makes the flame retardation performance durable and effective. The polyimide resin shell layer and the silane coupling agent modification significantly improve the compatibility of the flame retardant and the polyvinyl chloride matrix, and reduce the mechanical property decline caused by the addition of fillers. Moreover, the smoke emission during combustion of the intumescent flame retardant system is much lower than that of the halogen-containing system, and the polyimide resin itself has good carbonization, which further suppresses smoke.

[0019] The modified dibenzoylmethane / choline compound prepared by the method has choline grafted on dibenzoylmethane, and the choline has a typical quaternary ammonium salt group; the prepared dibenzoylmethane / choline compound has a typical β-diketone structure, and when used in combination with a calcium-zinc stabilizer, the thermal stability of the stabilizer is significantly improved; the quaternary ammonium salt structure of choline provides long-lasting and efficient antibacterial and mildew-proof functions; and then, by reacting the hydroxyl group with octadecyl isocyanate, long-chain alkyl groups are grafted on the dibenzoylmethane / choline compound, the introduction of the long-chain alkyl groups greatly enhances the compatibility of the dibenzoylmethane / choline compound with a polyvinyl chloride matrix, effectively prevents migration and precipitation of the dibenzoylmethane / choline compound as a small molecule additive, and ensures the durability of the performance. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0021] The preparation method of the modified composite flame retardant in Embodiment 1 includes the following steps: 63.7 g of melamine and 20 mL of distilled water were added to a four-necked flask, and the temperature was raised to 75℃, and the mixture was stirred at 300 r to be uniform, and the pH was adjusted to 8 by using a 0.1 mol / L sodium hydroxide aqueous solution, and 75 mL of a 37% formaldehyde solution was added dropwise to the four-necked flask at a speed of 1 d / s, and the reaction was performed for 1 h until the solution was clear and transparent, and then the water was removed by rotary evaporation, and the solution was washed with distilled water for 3 times, and then the solution was dried in an oven at 105℃, and then 133.4 g of a pyrazinium pyrophosphate solution in acetonitrile was added, and the temperature was raised to reflux to react for 48 h, and then the reaction was cooled to room temperature, and then the product was filtered and washed, and then the product was dried in an oven at 105℃, to obtain an intumescent flame retardant; 100 g of ammonium polyphosphate was dispersed in a mixed solution of 300 mL of ethanol and water, and the mixture was placed in a 40℃ water bath and stirred at a speed of 300 rpm, and the pH of the system was adjusted to 4.5 by using an acetic acid aqueous solution, and a hydrolyzate containing 1.5 g of γ-aminopropyl triethoxysilane was added dropwise, and after the addition was completed, the temperature was raised to 60℃, and the reflux reaction was continued for 6 hours, and then the reaction was cooled to room temperature, and then the product was centrifuged and washed, and then the product was dried in a vacuum drying oven at 80℃, to obtain modified ammonium polyphosphate; The 50 g of the above intumescent flame retardant and 50 g of the above modified ammonium polyphosphate were put into a high-speed mixer and mixed at 1000 rpm for 5-10 minutes at 50°C. After ensuring that the two were fully and uniformly mixed, they were dispersed in 400 mL of anhydrous ethanol, and an aqueous acetic acid solution was added to adjust the pH to 6. A solution containing 20 g of a polyimide resin in dimethylacetamide was added, and the mixture was stirred and kept at 60°C for 2 h. After cooling to room temperature, spray drying was performed at a feed rate of 20 mL / min, an inlet temperature of 80°C, and an outlet temperature of 65°C to obtain a modified composite flame retardant.

[0022] Example 2 The preparation method of the modified composite flame retardant includes the following steps: The 75 g of the intumescent flame retardant prepared in Example 1 and the 50 g of the modified ammonium polyphosphate prepared in Example 1 were put into a high-speed mixer and mixed at 1000 rpm for 5-10 minutes at 50°C. After ensuring that the two were fully and uniformly mixed, they were dispersed in 400 mL of anhydrous ethanol, and an aqueous acetic acid solution was added to adjust the pH to 6. A solution containing 30 g of a polyimide resin in dimethylacetamide was added, and the mixture was stirred and kept at 60°C for 2 h. After cooling to room temperature, spray drying was performed at a feed rate of 20 mL / min, an inlet temperature of 80°C, and an outlet temperature of 65°C to obtain a modified composite flame retardant.

[0023] Example 3 The preparation method of the modified dibenzoylmethane / choline compound includes the following steps: 30 mmol of dibenzoylmethane was dissolved in 400 mL of ethanol, the pH was adjusted to 6.5 with sodium hydroxide, and then 30 mmol of choline was added. The mixture was stirred at 60°C for 10 h at a stirring speed of 300 r / min. After the reaction was completed, the product was separated by centrifugation and washed with ethanol three times to obtain a dibenzoylmethane / choline compound. 10 g of the dibenzoylmethane / choline compound and 150 mL of anhydrous N,N-dimethylformamide were mixed, and nitrogen was introduced for protection. The temperature was raised to 70°C, and a solution containing 11 g of octadecyl isocyanate in anhydrous N,N-dimethylformamide was added dropwise. The addition was controlled to be completed within 40 minutes. After the addition was completed, the reaction was continued at 70°C for 6 h. After precipitation, filtration, washing, and drying, a modified dibenzoylmethane / choline compound was obtained.

[0024] Example 4 The preparation method of the material of the sheath layer includes the following steps: Put 100 parts by mass of polyvinyl chloride resin (PVC-SG5), 6 parts by mass of chlorinated polyethylene (CPE, 135A), 40 parts by mass of polyester plasticizer (T-114), 30 parts by mass of modified composite flame retardant prepared in Example 1, 1 part by mass of modified dibenzoylmethane / choline compound prepared in Example 3, 3 parts by mass of calcium / zinc composite stabilizer, 15 parts by mass of nano calcium carbonate, 0.2 parts by mass of antioxidant 1010, 1 part by mass of polyethylene wax, and 1 part by mass of stearic acid into a high-speed mixer, mix at 110°C for 10 min, then cool to 40°C to discharge, melt plasticize through a double-screw extruder at 160-175°C, and pelletize to obtain a material for preparing a sheath layer.

[0025] The method for preparing a power cable for low-voltage electrical equipment includes the following steps: Twist 0.20 mm fine copper wire to obtain a conductor core; Form a thermoplastic polyester elastomer (TPEE) on the surface of the conductor core to form an insulation layer; Put the material for preparing a sheath layer prepared in this embodiment into a single-screw extruder, extrude a sheath layer on the surface of the above-mentioned insulation layer at 170-180°C, and wind after water cooling to obtain a power cable for low-voltage electrical equipment.

[0026] In the preparation step of the material for the sheath layer, compared with Example 4, this embodiment only replaces the modified composite flame retardant prepared in Example 1 added in Example 4 with the same mass of the modified composite flame retardant prepared in Example 2, and the rest of the components and the preparation method are completely consistent with Example 4.

[0027] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, this embodiment only replaces the material for the sheath layer prepared in Example 4 added in Example 4 with the same mass of the material for the sheath layer prepared in this embodiment, and the rest of the components and the preparation method are completely consistent with Example 4.

[0028] The method for preparing a material for a sheath layer includes the following steps: Put 100 parts by mass of polyvinyl chloride resin (PVC-SG5), 6 parts by mass of chlorinated polyethylene (CPE, 135A), 40 parts by mass of polyester plasticizer (T-114), 30 parts by mass of modified composite flame retardant prepared in Example 1, 1 part by mass of modified dibenzoylmethane / choline compound prepared in Example 3, 3 parts by mass of calcium / zinc composite stabilizer, 15 parts by mass of nano calcium carbonate, 0.2 parts by mass of antioxidant 1010, 1 part by mass of polyethylene wax, and 1 part by mass of stearic acid into a high-speed mixer, mix at 110°C for 10 min, then cool to 40°C to discharge, melt plasticize through a double-screw extruder at 160-175°C, and pelletize to obtain a material for preparing a sheath layer.

[0029] The method for preparing the power cable for low-voltage electrical equipment comprises the following steps: Twist 0.20 mm fine copper wire to obtain a conductor core; Form an insulating layer on the surface of the conductor core with thermoplastic polyester elastomer (TPEE); Put the material of the sheath layer prepared in this embodiment into a single-screw extruder, and extrude the material on the surface of the insulating layer at 170-180°C to form a sheath layer. After water cooling, the sheath layer is wound up to obtain the power cable for low-voltage electrical equipment.

[0030] In the preparation step of the material of the sheath layer, compared with Example 6, this embodiment only replaces the modified composite flame retardant prepared in Example 1 added in Example 6 with the same mass of the modified composite flame retardant prepared in Example 2, and the rest of the components and the preparation method are completely consistent with Example 6.

[0031] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 6, this embodiment only replaces the material of the sheath layer prepared in Example 6 added in Example 6 with the same mass of the material of the sheath layer prepared in this embodiment, and the rest of the components and the preparation method are completely consistent with Example 6.

[0032] The method for preparing the composite flame retardant comprises the following steps: Put 50 g of the intumescent flame retardant prepared in Example 1 and 50 g of the modified ammonium polyphosphate prepared in Example 1 into a high-speed mixer, mix at 50°C at a speed of 1000 rpm for 5-10 minutes, and obtain the composite flame retardant after ensuring that the two are fully and uniformly mixed.

[0033] In the preparation step of the material of the sheath layer, compared with Example 4, this embodiment only replaces the modified composite flame retardant prepared in Example 1 added in Example 4 with the same mass of the composite flame retardant prepared in Comparative Example 1, and the rest of the components and the preparation method are completely consistent with Example 4.

[0034] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, this embodiment only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the same mass of the material of the sheath layer prepared in Comparative Example 2, and the rest of the components and the preparation method are completely consistent with Example 4.

[0035] In the preparation step of the material of the sheath layer, compared with Example 4, this embodiment only replaces the modified composite flame retardant prepared in Example 1 added in Example 4 with the same mass of the intumescent flame retardant prepared in Example 1, and the rest of the components and the preparation method are completely consistent with Example 4.

[0036] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, Comparative Example 3 only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the material of the sheath layer prepared in Comparative Example 3 in equal quality, and the rest of the components and the preparation method are completely consistent with Example 4.

[0037] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, Comparative Example 3 only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the material of the sheath layer prepared in Comparative Example 3 in equal quality, and the rest of the components and the preparation method are completely consistent with Example 4.

[0038] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, Comparative Example 3 only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the material of the sheath layer prepared in Comparative Example 3 in equal quality, and the rest of the components and the preparation method are completely consistent with Example 4.

[0039] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, Comparative Example 3 only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the material of the sheath layer prepared in Comparative Example 3 in equal quality, and the rest of the components and the preparation method are completely consistent with Example 4.

[0040] In the preparation step of the power cable for low-voltage electrical equipment, compared with Example 4, Comparative Example 3 only replaces the material of the sheath layer prepared in Example 4 added in Example 4 with the material of the sheath layer prepared in Comparative Example 3 in equal quality, and the rest of the components and the preparation method are completely consistent with Example 4.

[0041] Performance test Tensile property: according to GB / T 1040-2006, the sheath layer samples prepared in Examples 4-7 and Comparative Examples 2-5 were cut into samples with a size of 170 mm x 10 mm x 4 mm, and the tensile rate was 50 mm / min; 5 samples were tested for each group of samples, and the average value was taken; the test results are shown in Table 1. Charpy notched impact strength: according to GB / T 1043-2008, the sheath layer samples prepared in Examples 4-7 and Comparative Examples 2-5 were cut into samples with a size of 80 mm x 10 mm x 4 mm, the V-shaped notch depth was 2 mm, the pendulum energy was 7.5 J, and the impact speed was 3.8 m / s; 5 samples were tested for each group of samples, and the average value was taken; the test results are shown in Table 1. Vertical burning: according to UL94-2018, the sheath layer samples prepared in Examples 4-7 and Comparative Examples 2-5 were cut into samples with a size of 120 mm x 16.5 mm x 2 mm, and 5 samples were tested for each group of samples, and the average value was taken; the test results are shown in Table 1. Vicat softening temperature: tested according to GB / T 1633-2000, heating rate of 120℃ / h, load of 10N; the test results are shown in Table 1; Limiting oxygen index: tested according to ASTM D2863-2012, the sheath layer samples prepared in Examples 4-7 and Comparative Examples 2-5 were cut into samples of 120mm x 16.5mm x 2mm, 5 sample strips were tested for each group of samples, and the average value was taken; the test results are shown in Table 1; Table 1: Performance test data statistics table of sheath layer in Examples 4-7 and Comparative Examples 2-5

[0042] As can be seen from Table 1, the sheath layer of the power cable for low-voltage electrical equipment prepared by the present application has good mechanical properties and flame retardant properties. The test data shows that the polyimide resin coating and the silane coupling agent modification greatly improve the compatibility of the flame retardant and the polyvinyl chloride resin matrix, reduce the stress defect points, and the polyimide resin also improves the heat resistance of the material. The modified composite flame retardant prepared in the present application has a synergistic flame-retardant tube effect, and the modified dibenzoylmethane / choline compound and calcium / zinc composite stabilizer have a synergistic thermal stabilizing effect.

[0043] Antibacterial test: using the standard ISO 22196:2011, by comparing the change in the number of bacteria before and after inoculation, the antibacterial rate of the sheath layer prepared in Examples 4-7 and Comparative Examples 2-5 on two representative microorganisms Escherichia coli (E. coli) and Staphylococcus aureus was calculated, and each test was repeated 3 times; the test results are shown in Table 2; Water resistance test: the sheath layer samples prepared in Examples 4-7 and Comparative Examples 2-5 were dried in an oven (70℃), and the weight of each sample was recorded after drying to constant weight. Then the dried samples were immersed in deionized water and placed in an oven to maintain a constant temperature of 70℃. Every 24h, the deionized water was replaced and 3 sets of samples were taken out and wiped dry. The weight of the samples was recorded. The total soaking time was 168h. The mass change rate of the sample during soaking was the water absorption rate of the material. After 168h, the sample strips after the water resistance test were taken out for corresponding tests. The change in the corresponding data before and after the water resistance test indicates the moisture resistance performance; ΔLOI represents the change rate of limiting oxygen index, which is the LOI before the water resistance test and the LOI' after 168h of water resistance test. It is calculated by ΔLOI= (LOI-LOI') LOI / ×100%; Tensile strength change rate (Δδ) is the tensile strength before soaking and the tensile strength δ' after soaking for 168h, which is calculated by Δδ= (δ-δ') / δ×100%; The water absorption of the composite material is calculated by AW=(W'-W) / W, wherein W is the mass before soaking and W' is the mass after soaking; the test results are shown in Table 2. Table 2: Performance test data statistics table of the sheath layer in Examples 4-7 and Comparative Examples 2-5

[0044] As shown in Table 2, the sheath layer of the power cable for low-voltage electrical equipment prepared in the application has good antibacterial property and moisture resistance. The test data show that the benzoyl methane / choline compound prepared in the application has antibacterial property, which can endow the power cable for low-voltage electrical equipment with antibacterial and mildew-proof properties, thereby improving the service life, and the long-chain alkyl modification of the benzoyl methane / choline compound makes the antibacterial property better. After the flame retardant is coated on the polyimide resin, the water resistance is greatly improved, thereby ensuring the long-term durability of the flame-retardant property and mechanical property of the sheath layer.

[0045] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0046] The above describes one embodiment of the present application in detail, but the content described is only the preferred embodiment of the present application and cannot be considered as limiting the scope of the implementation of the present application. Any equivalent changes and improvements made in the scope of the present application should still belong to the patent coverage of the present application.

Claims

1. A power cable for low voltage electrical equipment, characterized in that, From inside to outside, at least including a conductor core, an insulation layer wrapped outside the conductor core, and a sheath layer wrapped outside the insulation layer; The sheath layer at least includes the following mass parts of raw materials: Polyvinyl chloride resin 100 parts; chlorinated polyethylene 5-8 parts; polyester plasticizer 35-45 parts; modified composite flame retardant 25-35 parts; modified dibenzoylmethane / choline compound 0.5-1.5 parts; calcium / zinc composite heat stabilizer 2-4 parts; inorganic filler 10-20 parts; antioxidant 0.1-0.3 parts; lubricant 0.8-2 parts.

2. A power cable for low voltage electrical equipment according to claim 1, characterized in that, The preparation method of the modified composite flame retardant comprises the following steps: Melamine is added to distilled water, the pH is adjusted to 8-8.5, then formaldehyde solution is added dropwise, after reaction, pyrazophosphoric acid solution is added, after reaction, washing and drying, an intumescent flame retardant is obtained; Ammonium polyphosphate is dispersed in deionized water, hydrolyzate of gamma-aminopropyl triethoxysilane is added, after reaction, washing and drying, modified ammonium polyphosphate is obtained; The intumescent flame retardant and the modified ammonium polyphosphate are mixed and then dispersed in anhydrous ethanol, the pH is adjusted to 6-6.5, dimethylacetamide solution of polyimide resin is added, and spray drying is performed to obtain a composite modified flame retardant.

3. A power cable for low voltage electrical equipment according to claim 2, characterized in that, The mass fraction of the formaldehyde solution is 35-40%, and the mass ratio of the melamine, the formaldehyde and the pyrazophosphoric acid is 12-13:5-6:27-28.

4. The power cable for low voltage electrical equipment according to claim 2, wherein The mass ratio of the ammonium polyphosphate and the gamma-aminopropyl triethoxysilane is 1:0.01-0.

02.

5. The power cable for low voltage electrical equipment according to claim 2, wherein The mass ratio of the intumescent flame retardant and the modified ammonium polyphosphate is 1-2:1, and the mass ratio of the total weight of the intumescent flame retardant and the modified ammonium polyphosphate to the polyimide resin is 1:0.15-0.

3.

6. The power cable for low voltage electrical equipment according to claim 1, wherein The preparation method of the modified dibenzoylmethane / choline compound comprises the following steps: Dibenzoylmethane is dissolved in ethanol, the pH is adjusted to 6-6.5, choline is added, and after reaction, a dibenzoylmethane / choline compound is obtained; The dibenzoylmethane / choline compound and N,N-dimethylformamide are mixed, N,N-dimethylformamide solution of octadecyl isocyanate is added under nitrogen protection, after reaction, washing and drying, a modified dibenzoylmethane / choline compound is obtained.

7. A power cable for low voltage electrical equipment according to claim 6, characterized in that, The molar ratio of the dibenzoylmethane and the choline is 1:1, and the mass ratio of the dibenzoylmethane / choline compound and the octadecyl isocyanate is 1:0.8-1.

2.

8. The power cable for low voltage electrical equipment according to claim 1, wherein The inorganic filler is a mixture of one or more of aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, clay, mica or kaolin, the lubricant is a mixture of one or more of zinc stearate, white wax, stearic acid and polyethylene wax, and the antioxidant is a mixture of one or more of phenolic antioxidant, phosphite antioxidant or amine antioxidant.

9. A method of producing a power cable for low voltage electrical equipment as claimed in any one of claims 1 to 8, characterized in that, At least including the following steps: An insulation layer is formed by extruding insulation layer material on the surface of the conductor core through an extruder, a sheath layer is formed by extruding sheath layer material outside the insulation layer through an extruder, and after cooling and setting, a power cable for low-voltage electrical equipment is obtained.

10. The method of claim 9, wherein the power cable for low voltage electrical equipment is prepared by the steps of: The conductor core is twisted by a plurality of fine copper wires, and the material of the insulation layer is thermoplastic polyester elastomer.

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