JPH056767B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a crosslinked polyethylene insulated wire, and more particularly to a wire formed by covering a single conductor with crosslinked polyethylene. (Prior art) Insulated wires made by covering a single conductor with cross-linked polyethylene are generally produced by covering polyethylene to which a cross-linking agent has been added, heating this at high temperature to cross-link it, and then cooling it under pressure. Ru. (Problems to be Solved by the Invention) However, when the insulating layer becomes thicker, it cools from the outside and hardens during cooling, resulting in a gap between the insulating layer and the conductor, which causes a problem in that electrical performance deteriorates. There are methods to solve this problem, such as roughening the conductor surface or providing an adhesive layer on the conductor surface, but this method results in extremely close contact between the conductor and the insulation layer, and the insulation is removed at the terminal. It becomes difficult to do so. In view of the above, the present invention was developed to solve these problems. (Means for Solving the Problems) That is, the present invention provides an electric wire in which a single conductor is coated with cross-linked polyethylene, an insulating layer 3 is provided at the boundary between the conductor 1 and the cross-linked polyethylene 2, and the insulating layer is composed of an ethylene vinyl acetate copolymer, an ethylene acrylic copolymer, or an ethylene α-olefin copolymer, and furthermore, the VICAT softening point of the composition is lower than that of the uncrosslinked polyethylene of the crosslinked polyethylene. This is a crosslinked polyethylene insulated wire that is characterized by a temperature lower than that and 30°C or higher (see Figure 1). The insulating layer 3 is present as a part of the insulating layer body of the electric wire. (Function) As described above, the degree of adhesion between the cross-linked polyethylene insulating layer and the conductor is moderate, so that there is no gap between the insulating layer and the conductor, and the insulation is easily removed during terminal work.A cross-linked polyethylene insulated wire is provided. The present invention will be explained in detail below. In order to improve the above-mentioned problems, the present invention has conducted various studies, and as a result, VICAT material whose softening point is lower than that of non-crosslinked polyethylene for insulating cross-linked polyethylene is used at the interface between the conductor and the cross-linked polyethylene insulation, for example 0.05.
It was discovered that if applied to a thickness of about 0.3 mm to 0.3 mm, this layer would prevent gaps between the conductor and insulating layers even when manufactured using the same conventional method. If the VICAT softening point is higher than that of the uncrosslinked polyethylene containing a crosslinking agent in the insulating crosslinked polyethylene, the amorphous amorphous portion involved in adhesion is small and the desired adhesion cannot be obtained. It has been found that when VICAT with a softening point of less than 30°C is used, gaps do not occur, but the adhesion between the conductor and the insulation increases, making the peelability of the insulation significantly worse. The VICAT softening point is the thermal deformation temperature of plastic plastic specified in JIS K 7206, and the lower the temperature, the more amorphous (non-crystalline region) portions are present, and the softer the material is. The material used here is preferably a polymer that is easily fused to polyethylene, such as ethylene vinyl acetate copolymer or ethylene α-olefin copolymer (trade name: Tafmer). Any method of coating the conductor may be used as long as it can be coated uniformly, such as by using an extruder or by dissolving it in a solvent. Examples will be described below to help understand the present invention. (Example) In order to confirm the effects of the present invention, a 2.0 mmφ copper wire 1 was extruded and coated with various polymers 3 to a thickness of 0.1 mm, and then cross-linked polyethylene 2 was coated to a thickness of 4 mm.
Electric wires were created by heating and cross-linking them at a saturated vapor pressure of Kg/cm ² (see Figure 1), cutting them into 30 cm lengths, measuring the resistance when pulling out the copper wires, and then using an insulating cross-linked polyethylene layer. We compared whether resin remained on the copper wire when it was removed. The results are shown in Table 1, and it can be seen that the electric wire of the present invention has excellent workability during terminal work.

[Table] (Effects of the Invention) As described above, according to the present invention, there is no gap between the insulating layer and the conductor, there is no deterioration in electrical performance, and the insulation can be easily stripped off during terminal work. An insulated wire coated with cross-linked polyethylene is obtained.

[Brief explanation of the drawing]

FIG. 1 illustrates a cross-sectional view of the crosslinked polyethylene insulated wire of the present invention. 1 conductor, 2 cross-linked polyethylene insulation, 3 insulation layers.

Claims (1)

[Claims] 1. In electric wires in which a single conductor is coated with cross-linked polyethylene, an insulating layer is provided at the boundary between the conductor and the cross-linked polyethylene, and the insulating layer is made of ethylene vinyl acetate copolymer, ethylene acrylic copolymer, or ethylene α-olefin. consisting of any composition of copolymers, and further comprising VICAT of the composition.
A crosslinked polyethylene insulated wire, characterized in that the softening point of the crosslinked polyethylene is lower than that of uncrosslinked polyethylene and is 30°C or higher.