Flame-retardant electric wire for extremely cold environment and method for manufacturing the same

Abstract

The present application relates to the technical field of cable, specifically to a flame-retardant electric wire suitable for extremely cold environment, comprising a conductor and a composite insulation layer covering the conductor; the raw materials of the composite insulation layer comprise, by weight fraction: 70-90 parts of a high molecular alloy matrix resin of ethylene-vinyl acetate copolymer and linear low-density polyethylene, 15-25 parts of cold-resistant plasticizer, 10-20 parts of hydrogenated styrene-butadiene-styrene block copolymer elastomer, 30-45 parts of halogen-free flame-retardant system, and 3-8 parts of antioxidant, lubricant and processing aid; the present application has excellent flexibility and impact resistance under-40 DEG C extremely cold environment, solves the low-temperature embrittlement problem of conventional PVC electric wire, and the halogen-free flame-retardant performance reaches the high-grade standard of indoor wiring, solving the problem of insufficient flame retardance of some cold-resistant electric wire.

Description

Technical Field

[0001] This invention relates to the technical field of cables, specifically to a flame-retardant wire suitable for extremely cold environments and its preparation method. Background Technology

[0002] With the rapid development of the construction industry, the demand for electrical decoration in residences, villas, sunrooms, garages, and low-temperature storage rooms in Northeast China, Northwest China, and some high-altitude and frigid regions is increasing, which places higher demands on the environmental adaptability and safety performance of home wiring.

[0003] Conventional household electrical wiring commonly uses polyvinyl chloride (PVC) as insulation material. Its low-temperature performance is poor; national standards stipulate that its applicable ambient temperature should generally not be lower than -15℃. When the ambient temperature drops below -25℃, the PVC insulation layer undergoes severe hardening and embrittlement. During wire installation, bending, or when subjected to minor external impacts, the insulation layer is highly susceptible to cracking or even breakage, leading to insulation failure and causing serious electrical safety hazards such as leakage and short circuits. This severely threatens the lives and property of residents in extremely cold regions.

[0004] Although there are some cold-resistant electrical wire products on the market, these products are mostly designed for outdoor overhead or industrial use scenarios and have obvious technical defects: First, the product structure design is heavy, and if a rubber sheath is used, it does not meet the space constraints of concealed works in interior decoration; Second, the flame retardant performance is insufficient and does not meet the high flame retardant standards for internal building wiring, thus failing to meet the stringent requirements for indoor electrical safety.

[0005] In summary, the lack of a suitable home decoration wire that can simultaneously meet the requirements of maintaining excellent flexibility and impact resistance at extremely low temperatures of -40℃, comply with indoor wiring VW-1 level or higher flame retardant standards, and have a diameter and flexibility comparable to conventional home decoration wires for easy conduit installation has become a key issue restricting the quality and safety of indoor electrical decoration in extremely cold regions. There is an urgent need to develop a highly flexible flame retardant wire for home decoration that is suitable for extremely cold environments.

[0006] Based on this, the present invention designs a flame-retardant wire suitable for extremely cold environments and its preparation method to solve the above problems. Summary of the Invention

[0007] To achieve the above objectives, the present invention provides the following technical solution: a flame-retardant wire suitable for extremely cold environments, comprising a conductor and a composite insulation layer covering the conductor; the raw materials of the composite insulation layer, by weight, include: 70-90 parts of a polymer alloy matrix resin of ethylene-vinyl acetate copolymer and linear low-density polyethylene, 15-25 parts of a cold-resistant plasticizer, 10-20 parts of a hydrogenated styrene-butadiene-styrene block copolymer elastomer, 30-45 parts of a halogen-free flame-retardant system, and 3-8 parts of antioxidants, lubricants and processing aids.

[0008] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 28%-33%.

[0009] Preferably, the cold-resistant plasticizer is at least one of dioctyl adipate and dibutyl sebacate.

[0010] Preferably, the halogen-free flame retardant system is composed of at least one halogen-free flame retardant selected from modified aluminum hydroxide and magnesium hydroxide, combined with a silicone powder synergist.

[0011] Preferably, the composite insulating layer is cross-linked by electron beam irradiation to form a three-dimensional network molecular structure.

[0012] Preferably, the conductor is a soft copper conductor made of multiple strands of oxygen-free fine copper wires twisted together, providing basic bending performance for the wire.

[0013] Preferably, a thin-walled colored outer protective layer is extruded over the composite insulation layer, the outer protective layer being made of PVC material or a cold-resistant material of the same grade as the composite insulation layer.

[0014] Preferably, a method for preparing a flame-retardant wire suitable for extremely cold environments includes the following steps: S1. Conductor preparation: drawing, annealing, and stranding oxygen-free copper rods to form a flexible multi-strand copper conductor; S2. Insulation material granulation: The raw materials of the composite insulation layer are premixed in a high-speed mixer, and then melted, mixed and granulated by a twin-screw extruder to obtain cold-resistant insulation masterbatch; S3. Extrusion insulation: Cold-resistant insulation masterbatch is fed into a wire extruder, and the molten insulation material is tightly and evenly coated onto the conductor using an extrusion die. The conductor is then cooled and shaped in a water bath. S4. Spark test and winding: After cooling, the wire is subjected to online high-voltage spark testing to ensure that the insulation is free of defects before winding and packaging.

[0015] Preferably, an irradiation crosslinking step is provided between steps S3 and S4: the cooled wire is subjected to electron beam irradiation treatment.

[0016] In summary, this application has the following beneficial technical effects: Extreme low temperature resistance: Through the synergistic effect of polymer alloy matrix, special cold-resistant plasticizer and elastomer, the wire insulation layer can still maintain excellent flexibility and impact resistance in the extremely cold environment of -40℃. It can be easily bent and rolled without cracking, which completely solves the problem of winter construction and long-term use of home decoration wires in cold regions. Excellent flame retardant safety: Adopting a highly efficient halogen-free flame retardant system, the product meets the strict flame retardant requirements of indoor wiring while maintaining flexibility. It produces low smoke, is halogen-free, and self-extinguishing when exposed to fire, greatly improving the electrical safety level inside buildings. Excellent overall performance: Through irradiation cross-linking process, the product has a high heat resistance level, with a long-term allowable operating temperature of up to 125℃ and strong overload capacity; the insulation layer has good mechanical strength, wear resistance, and long service life. Easy to install: The product's outer diameter and flexibility are designed to be comparable to that of regular household wiring, making it fully compatible with standard conduits and junction boxes. Electricians can install it without special tools or skills, ensuring good compatibility. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the cable structure in Example 1.

[0019] Figure 2 This is a schematic diagram of the cable structure in Embodiment 2.

[0020] The attached diagram lists the components represented by each number as follows: 1. Conductor; 2. Composite insulation layer; 3. Small composite insulation layer; 4. Large composite insulation layer; 5. Soft copper conductor; 6. Outer protective layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0023] Reference Figure 1 This is a flame-retardant wire suitable for extremely cold environments, as described in Example 1. Specifically, it is a single-core cold-resistant home decoration wire (BV type) with a specification of 2.5mm². BV type refers to copper core polyvinyl chloride insulated cloth wire.

[0024] Conductor 1: It is made of 19 oxygen-free copper wires with a diameter of 0.41mm twisted together, with a specification of 2.5mm².

[0025] Composite insulation layer 2: 0.8mm thick.

[0026] Outer protective layer 6: Made of the same cold-resistant material as composite insulation layer 2, with a thickness of 0.5 mm, it covers the outside of composite insulation layer 2.

[0027] The raw materials for composite insulation layer 2 are formulated from the following components, by weight: 80 parts of a polymer alloy formed by mixing EVA and linear low-density polyethylene (LLDPE), wherein (EVA) is an ethylene-vinyl acetate copolymer, and the vinyl acetate (VA) content is 30%; 20 parts of dioctyl adipate (DOA); 15 parts of ethylene-butene copolymer; 40 parts of nano-modified aluminum hydroxide; 5 parts of silicone powder; 1 part of antioxidant; 2 parts of calcium stearate lubricant.

[0028] A method for preparing flame-retardant wires suitable for extremely cold environments, used in the preparation process of composite insulation layer 2 in Example 1, includes the following steps: Step 1, conductor 1 preparation: drawing oxygen-free copper rods to 0.41mm, annealing them, and then bundling 19 copper wires into a 2.5mm² soft copper conductor 5; Step 2, Insulation material granulation: Put each raw material of composite insulation layer 2 into a high-speed mixer for premixing for 15 minutes, then add it to a twin-screw extruder and melt-mix and granulate at 150-170℃ to obtain cold-resistant insulation masterbatch; Step 3, extrusion insulation: The cold-resistant insulation masterbatch is fed into the wire extruder. At a processing temperature of 160-185℃, the molten insulation material is evenly coated onto conductor 1 through an extrusion die. After cooling and shaping in a water bath, an insulated wire core is formed. Step 4, Irradiation crosslinking: The insulated wire core is subjected to electron beam irradiation treatment with an irradiation dose of 15 Mrad; Step 5, Spark Test and Rewinding: The irradiated wire is subjected to a 5000V online high-voltage spark test. After passing the test, it is rewound and packaged to obtain the finished product.

[0029] In this embodiment, the matrix resin, a polymer alloy of ethylene-vinyl acetate copolymer and linear low-density polyethylene, takes into account the basic flexibility, low-temperature resistance and processability of the resin, providing matrix support for performance in extremely cold environments; the addition of cold-resistant plasticizers effectively improves the low-temperature plasticity and toughness of the insulation layer and avoids low-temperature hardening and embrittlement.

[0030] Reference Figure 2 This is a flame-retardant wire suitable for extremely cold environments in this embodiment 2, specifically a three-core cold-resistant sheathed wire (BVV type) with a specification of 3×2.5mm². BVV type refers to a lightweight polyvinyl chloride sheathed cable.

[0031] Conductor 1: It is a 2.5mm² soft copper conductor 5 made of 19 oxygen-free copper wires with a diameter of 0.41mm twisted together. There are a total of 3 soft copper conductors 5 forming one conductor 1. Composite insulation layer 2: includes small composite insulation layer 3 and large composite insulation layer 4. The large composite insulation layer 4 and small composite insulation layer 3 are consistent with the raw material formula of Example 1. The small composite insulation layer 3 is wrapped on the three soft copper conductors 5, and is colored red (phase wire), blue (neutral wire), and yellow-green bicolor (ground wire) respectively. The large composite insulation layer 4 wraps the three soft copper conductors 5. Outer protective layer 6: Made of the same cold-resistant material as composite insulation layer 2, with a thickness of 0.5mm, it covers the outside of the large composite insulation layer 4.

[0032] A method for preparing flame-retardant wires suitable for extremely cold environments, used in the preparation process of flame-retardant wires in Example 2, includes the following steps: Step 1, soft copper conductor preparation: Prepare 3 soft copper conductors of different colors, 2.5mm², according to the method in Example 1; Step 2, cabling and outer sheath extrusion: Three soft copper conductors are twisted into a cable, and then a cold-resistant outer protective layer is extruded on the outside of the cable core through an extruder, and then cooled and shaped in a water tank; Step 3, Spark Test and Rewinding: Perform a 5000V online high-voltage spark test on the finished wire. After passing the test, rewind and package it.

[0033] The flame-retardant wires prepared in Example 1 were tested, and the test results are shown in Table 1.

[0034]

[0035] Table 1. Measurement of various indicators of flame-retardant wires As shown in Table 1, all four items tested (flame retardancy, low temperature impact, low temperature winding, and low temperature tensile testing) passed the tests. The physical properties and flame retardancy of the sample in the extremely cold environment of -40℃ met the judgment requirements. Moreover, the test results of low temperature tensile testing and non-flame propagation test were far better than the standard threshold. The product's extreme cold resistance, flame retardancy, and flexibility-related properties met the standards.

[0036] The beneficial effects of this application are as follows: 1. It can maintain excellent flexibility and impact resistance in extremely cold environments of -40℃, solving the problem of low-temperature embrittlement of conventional PVC wires; 2. Its halogen-free flame retardant performance meets the high-level standards for indoor wiring, solving the problem of insufficient flame retardancy in some cold-resistant wires; 3. Its overall diameter and flexibility are comparable to conventional household wiring, making it suitable for indoor conduit and concealed engineering needs, and solving the problem of heavy structure in industrial cold-resistant wires.

[0037] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant wire suitable for extremely cold environments, characterized in that: It includes a conductor (1) and a composite insulation layer (2) covering the conductor (1); the raw materials of the composite insulation layer (2) include, by weight: 70-90 parts of a polymer alloy matrix resin of ethylene-vinyl acetate copolymer and linear low-density polyethylene, 15-25 parts of a cold-resistant plasticizer, 10-20 parts of a hydrogenated styrene-butadiene-styrene block copolymer elastomer, 30-45 parts of a halogen-free flame retardant system, and 3-8 parts of antioxidants, lubricants and processing aids.

2. The flame-retardant wire suitable for extremely cold environments according to claim 1, characterized in that: The vinyl acetate content in the ethylene-vinyl acetate copolymer is 28%-33%.

3. The flame-retardant wire suitable for extremely cold environments according to claim 2, characterized in that: The cold-resistant plasticizer is at least one of dioctyl adipate and dibutyl sebacate.

4. A flame-retardant wire suitable for extremely cold environments according to claim 1, characterized in that: The halogen-free flame retardant system is composed of at least one halogen-free flame retardant selected from modified aluminum hydroxide and magnesium hydroxide, combined with a silicone powder synergist.

5. A flame-retardant wire suitable for extremely cold environments according to claim 1, characterized in that: The composite insulating layer (2) is cross-linked by electron beam irradiation.

6. A flame-retardant wire suitable for extremely cold environments according to claim 1, characterized in that: The conductor (1) is a soft copper conductor (5) made of multiple strands of oxygen-free fine copper wires twisted together.

7. A flame-retardant wire suitable for extremely cold environments according to claim 5, characterized in that: A thin-walled colored outer protective layer (6) is extruded over the composite insulation layer (2). The outer protective layer (6) is made of PVC material or a cold-resistant material of the same grade as the composite insulation layer (2).

8. A method for preparing a flame-retardant wire suitable for extremely cold environments according to claims 1-7, characterized in that: Includes the following steps: S1. Conductor (1) preparation: oxygen-free copper rod is drawn, annealed and stranded to form a soft multi-strand copper conductor (1); S2. Insulation material granulation: The raw materials of the composite insulation layer (2) are premixed in a high-speed mixer, and then melted, mixed and granulated by a twin-screw extruder to obtain cold-resistant insulation masterbatch; S3. Extrusion insulation: Cold-resistant insulation masterbatch is fed into the wire extruder, and the molten insulation material is tightly and evenly coated on the conductor (1) using an extrusion die, and then cooled and shaped by water bath; S4. Spark test and winding: After cooling, the wire is subjected to online high-voltage spark testing to ensure that the insulation is free of defects before winding and packaging.

9. A method for preparing a flame-retardant wire suitable for extremely cold environments according to claim 8, characterized in that: Between steps S3 and S4, there is also an irradiation crosslinking step: the cooled wire is subjected to electron beam irradiation treatment.

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