JPH03219504A - Overhead wire - Google Patents

Abstract

PURPOSE:To prevent rust preventives from escaping in all directions outward due to moisture by installing a water barrier layer made up of resin whose water-vapor permeability is low on the outside of a resin insulating layer mixed with rust preventives. CONSTITUTION:A resin insulating layer 12 mixed with rust preventives is installed at the outside of a conductor 2 with which a plurality of copper strands 21 are inter-twisted, and the outside of the layer 12 is covered with a water barrier layer 11 to form an overhead wire. A resin whose water-vapor permeability is low, such as polychlorotrifluoroethylene, etc., is used to form the water barrier layer 11, and good in adhesiveness to the resin insulating layer 12. Thickness of the water barrier layer 11 is approximately 100mum-10mm in general. It is thereby possible to control the quantity of rust preventives escaping from the surface of the resin insulating layer due to moisture so that rest prevention of a conductor 2 becomes durable.

Description

[Detailed description of the invention] Industrial application field The present invention covers a resin insulating layer containing a rust preventive agent with a low moisture permeable resin to prevent the rust preventive agent from escaping to the outside, resulting in stress corrosion cracking resistance. Regarding superior overhead power lines.

Conventional technology and issues Overhead electric wires (OW, OE, QC) using stranded copper wires
) has long been an issue to prevent wire breakage accidents due to stress corrosion cracking.

Hitherto, overhead electric wires in which corrosion of stranded wires is suppressed and stress corrosion cracking resistance is improved have been known in which stranded wires are coated with a resin insulating layer containing a rust preventive agent. However, the effect was not completely satisfactory.

In view of the above, the group to which the present inventors belong first proposed a method in which the resin insulating layer is covered with a resin of the same quality (Utility Application No. 148840/1982).

Means for Solving the Problems The present invention is based on the new finding that the escape of rust preventive agents to the outside due to the involvement of moisture is greater than expected. It is more effective.

That is, the present invention consists of a plurality of copper-based strands twisted together inside a coating layer that has a water-blocking layer made of a resin with low moisture permeability on the outside of a resin insulating layer containing a rust preventive agent. The present invention provides an overhead electric wire characterized by having a conductor.

By creating a structure in which the resin insulating layer containing a rust preventive agent is covered with a water-blocking layer made of a low moisture permeable resin, it is possible to prevent the rust preventive agent from escaping to the outside due to the involvement of moisture. Corrosion prevention can be achieved over a long period of time by using a rust preventive agent for stranded wires.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplification of Constituent Elements of the Invention An overhead electric wire of the present invention is illustrated in the figure. 1 is a coating layer consisting of a water-shielding layer 11 and a resin insulating layer 12 containing a rust preventive agent, and 2 is a conductor formed by twisting a plurality of copper-based wires 21, that is, a twisted wire of copper-based wires. In addition to the above-mentioned components, the present invention may have a structure in which functional layers for various purposes are added.

For forming the resin insulating layer, an appropriate resin such as polyvinyl chloride or polyethylene may be used.

Further, as for the rust preventive agent, an appropriate one such as a triazole derivative such as benzotriazole or an imidazole derivative may be used. The general blending amount of the rust preventive agent is 100 parts by weight or less per 100 parts by weight of resin, especially 0.1 to 1.
It is 0 parts by weight.

A resin with low moisture permeability is used to form the water barrier layer. Examples include polychlorotrifluoroethylene, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymer, polyethylene, especially high density polyethylene, polyethylene terephthalate, tetrafluoroethylene/hexafluoroethylene copolymer, polyamide, etc. can give. When forming a water-blocking layer directly on the outside of a resin insulating layer using a two-layer extrusion molding method, etc., the combination of the resin forming the resin insulating layer and the resin forming the water-blocking layer is preferably one that has good adhesion. Incidentally, when the resin insulating layer is made of polyethylene, a water-blocking layer made of polychlorotrifluoroethylene or polyvinylidene chloride is preferable.

In the case of polyvinyl chloride, a water-blocking layer made of polyethylene or polyamide is preferred. The thickness of the water-blocking layer may be determined as appropriate, but is generally 1100 IJ to 10 mm.

The overhead electric wire of the present invention has strands of copper-based strands inside a coating layer consisting of a water-shielding layer and a resin insulating layer. It can be manufactured, for example, by forming a resin insulating layer and a water-blocking layer on the outside of a strand of copper-based strands using an extrusion molding method or the like.

Regarding the stranded copper wire to be coated, there are no particular limitations on the twist structure, number of twists, type of copper wire, etc. - The boat-like twisted structure is one in which a plurality of copper-based strands are twisted together on the outside of one central strand. Stranded copper wires, which can be preferably used from the viewpoint of stress corrosion cracking resistance, are subjected to both compression treatment and roll straightening treatment to reduce the gaps between copper wires in the stranded wires and increase the strand space. In addition to increasing the ratio, the residual stress of the copper-based strands in the stranded wire is reduced. The degree of compression treatment is based on the strand space factor of the stranded wire.
A suitable range is 0 to 95% (porosity 20 to 5%). The appropriate degree of roll straightening treatment is such that a bending strain of 0.1 to 0.6% is applied to the stranded wire.

Note that the compression treatment can be performed, for example, by passing the material through a die, and the roll straightening treatment can be performed, for example, by passing it in a meandering manner between straightening rolls arranged in the vertical and horizontal directions.

Effects of the Invention According to the present invention, a simple structure in which a water-blocking layer made of a low moisture permeability resin is provided on the outside of a resin insulation layer containing a rust preventive agent,
It is possible to effectively prevent the rust preventive agent from escaping to the outside, and the compounded rust preventive agent can be used highly effectively for preventing corrosion of copper-based wires. As a result, corrosion of the stranded copper wire can be prevented for a long period of time, stress corrosion cracking thereof can be prevented, and an overhead electric wire that is difficult to break and has excellent durability can be obtained.

Examples Example 1 A 60m wire with an initial strand space factor of about 76% (19/2.
0) Hard copper stranded wire is introduced into a die and compressed to make the wire space factor approximately 90%, and then passed meanderingly between straightening rolls for roll straightening treatment to achieve a bending distortion of 0.25%. A stranded wire loaded with was obtained. The repulsive force of the twisted wire is 2.5±1
．． 5kgf/mI+? Met.

Next, the above-mentioned stranded wire was introduced into a two-layer extruder, and on the outside thereof, a polyvinyl chloride layer (thickness 1.7 mm) containing 1% by weight of benzotriazole and a water-blocking layer (12η) made of nylon A thickness of 0.3 mm) was formed to obtain an overhead wire.

Comparative Example 1 An overhead electric wire was obtained according to Example 1 except that a water-blocking layer was not provided. However, the thickness of the polyvinyl chloride layer containing 1% by weight of benzotriazole was 2 mm.

Comparative Example 2 An overhead electric wire was obtained in accordance with Example 1, except that a polyvinyl chloride layer (no rust preventive added) with a thickness of 0.3 mm was used in place of the water-blocking layer.

Example 2 The same stranded wire as in Example 1 was introduced into a two-layer extruder, and on the outside was a polyethylene layer (thickness 1.7 mm) containing 1% by weight of benzotriazole and a water-shielding layer made of polyvinylidene chloride. A layer (thickness 0.3 mm) was formed to obtain an overhead wire.

Comparative Example 3 An overhead electric wire was obtained according to Example 2 except that a water-blocking layer was not provided. However, the thickness of the polyethylene layer containing 1% by weight of benzotriazole was 2 mm.

Comparative Example 4 An overhead electric wire was obtained in accordance with Example 2, except that a 0.3 mm thick polyethylene layer (no rust preventive added) was used in place of the water-blocking layer.

Evaluation Test [Residual Amount of Rust Preventive Agent] After the cut surfaces of the overhead wires obtained in Examples and Comparative Examples were waterproof and sealed, they were subjected to a heat cycle test at room temperature of -60°C in the air or in water. The amount of rust preventive agent remaining in the resin insulating layer after a predetermined period of time had elapsed was measured.

[Breakage time 1] A load of 20% of the tensile strength was applied to the overhead wires obtained in the Examples and Comparative Examples, and a 40 g/e copper acetate aqueous solution (35 The number of days until wire breakage was measured after immersing the wire in a temperature of

The above results are shown in the table.

In addition, regarding the rust preventive agent residual rate in the table, the content ratio of the rust preventive agent before immersion was taken as 100%.

[Brief explanation of drawings]

The figure is a sectional view of the embodiment. 1: Covering layer 11: Waterproof layer 12: Resin insulation layer 2: Twisted copper wire

Claims (1)

[Claims] 1. Inside the coating layer, which has a water-blocking layer made of a resin with low moisture permeability, on the outside of the resin insulation layer containing a rust preventive agent,
An overhead electric wire characterized by having a conductor formed by twisting a plurality of copper wires.