JPH0266807A - Insulation cable for outdoor use - Google Patents

Abstract

PURPOSE:To prevent a stress corrosion wire breaking due to corrosive rain drops by extruding a mixture obtained by adding the respectively predetermined amounts of polyester plasticizer, benzotriazol and/or benzotriazol derivative to olefin resin to cover a copper conductor. CONSTITUTION:A mixture of 0.05 to 10 weight parts of polyester plasticizer and 0.1 to 5 weight parts of benzotriazol and/or benzotriazol derivative added to 100 weight parts of olefin resin is extruded and applied to cover a copper conductor, thereby forming a corrosion protection cover. In this case, there are used one or more of adipic acid polyester, sebacic acid polyester, phthalic acid polyester, adipic acid-propylene glycol polyester, adipic acid-1,3 butylene glycol polyester and the like as the polyester plasticizer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention prevents discoloration of the copper wire even if corrosive rainwater enters the hard copper stranded wires of outdoor distribution lines, and prevents stress corrosion and disconnection. This invention relates to outdoor polyethylene insulated wires and outdoor crosslinked polyethylene insulated wires.

[Prior art]

Conventionally, vinyl chloride insulated wire (O
W), polyethylene insulated wire (OE), cross-linked polyethylene insulated wire (OC), etc.
When corrosive rainwater enters the inside of the wire, a black copper oxide film forms on the surface of the copper wire, which can lead to so-called stress corrosion cracking, where the hard copper strands break abnormally in the shape of a knife cut in a few years. This has become an important issue in terms of power security.

This stress corrosion disconnection is caused by the suspension of overhead power distribution lines.
Rainwater that has entered the inside of the wire from the terminal or connecting portion accumulates in the gaps between the insulator and the copper conductor, the gaps between the stranded wires, and accumulates in the bent portions between the utility poles. The water then becomes concentrated and corrosive, forming a thick black copper oxide film on the surface of the copper wire, selectively dissolving the underlying copper exposed at the crank part of the film and causing the wire to break. The progression of rainwater intrusion into the insulation coating of distribution lines is relatively quick when overhead distribution lines are first installed, and gradually slows down as rainwater is collected in ditches, until about 5 years later. After that, the number of intrusions becomes close to zero.

Even if a solution of benzotriazole dissolved in a volatile solvent such as alcohol is applied to stranded hard copper wire, a sufficient corrosion-resistant film is not formed to prevent stress corrosion and disconnection that occurs in such long-term corrosive environments. Therefore, there is a problem that long-term corrosion resistance effects cannot be expected.

Therefore, as a solution, 1) a sacrificial electrode is provided along the copper conductor, 2) an insulating layer is provided with an anti-rust component added to the copper layer, 2) a watertight mixture is filled in the hard copper strands, 2) It has been proposed that benzotriazole and its derivatives are dissolved in liquid paraffin, polybutene, silicone oil, etc. and coated on hard copper strands.

However, regarding (2), there is a problem that the sacrificial electrode is not properly melted and the copper conductor is not sufficiently protected. Regarding (2), there is a problem in that the rust preventive agent is difficult to dissolve from the insulating layer, it is difficult to prevent discoloration of the steel for a long period of time, and there is an undesirable problem that the insulation resistance of the insulating layer decreases. For ■, natural rubber, butyl rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber, etc. with a softener added, or mixtures of petrolactam gelatin, polybutene, polyisobutylene, microcrystal wax, polyethylene wax, soybean oil, etc. Alternatively, various watertight mixtures have been proposed, such as mixtures of ethylene-vinyl acetate copolymer and low-molecular-weight polyethylene or vinyl chloride copolymer, but they adhere to both conductors and insulators and prevent rainwater from penetrating. It is difficult to achieve watertightness by completely blocking the watertight admixture, and the manufacturing cost is also high. Removal of the watertight admixture is troublesome, and if the removal is not sufficient, there is a problem that the current carrying characteristics of the connection part deteriorates. ■Because water-repellent oil is used, it is difficult to form an anti-corrosion film between copper and benzotriazole, and its use reduces the adhesion between the insulator and the hard copper strands, resulting in a lack of pull-out strength. There is a problem.

[Problem that the invention seeks to solve]

The present inventors have previously discovered that if the copper rust preventive composition applied in Japanese Patent Application No. 63-37222 is applied to copper wire or copper stranded wire, a strong rust preventive film will be formed on the copper surface. Furthermore, it has been found that a film is formed to protect the film and exhibits a rust-preventing effect with excellent corrosion resistance even when exposed to a severe corrosive environment.

The present invention utilizes the above rust preventive composition for copper, and is effective against rainwater that enters the inside of the overhead distribution line from the retention section, terminal section, connection section, etc. of the overhead distribution line. The object of the present invention is to provide an outdoor insulated electric wire that can form a strong corrosion-resistant film on the surface of a hard copper stranded wire, maintain its copper color over a long period of time, and prevent stress corrosion and disconnection caused by corrosive rainwater.

[Means for solving problems]

The structure of the present invention is that an olefin resin 100 is placed on a copper conductor.
A mixture containing 0.05 to 10 parts by weight of a polyester plasticizer and 0.1 to 5 parts by weight of benzotriazole and/or benzotriazole derivative is extrusion coated, and an olefin resin is applied onto the coating by extrusion. An insulated wire for outdoor use is made by extrusion coating an insulator.

The configuration of the present invention will be further explained below.

The olefin resin used in the present invention includes, for example, low density polyethylene, ethylene-propylene rubber, ethylene-propylene-diene terpolymer, polybutene,
One or more resins such as ethylene ethyl acrylate copolymer, ethylene vinyl acetate copolymer, ethylene-vinyl acetate-vinyl chloride terpolymer, butyl rubber, and polyisobutylene are used in combination.

The polyester plasticizer used in the present invention includes adipic acid polyester, sebacic acid polyester, phthalic acid polyester, adipic acid-propylene glycol polyester, adipic acid-1,3-butylene glycol polyester, etc. One or more of these can be used.

In addition to benzotriazole, the rust inhibitors for copper used in the present invention include benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, Benzotriazole derivatives such as methylbenzotriazole cyclohexylamine salt can also be used in the same amount as the benzotriazole.

To dissolve benzotriazole etc. in a polyester plasticizer, dissolve the benzotriazole etc. in advance in an alcoholic solvent such as methanol or isopropyl alcohol, pour the liquid into the polyester plasticizer, mix and stir, and dissolve uniformly. be able to.

In the present invention, 0.05 to 10 parts by weight of the polyester plasticizer is blended with 100 parts by weight of the olefin resin, so that if it is less than 0.05 parts by weight, it has an excellent rust prevention effect regardless of the addition of the rust preventive agent. I can't expect that. On the other hand, if it exceeds 10 parts by weight, the plasticizer will excessively bloom on the insulating surface of the polyethylene insulator used as the jacket, which is not preferable for outdoor insulated wires.

The preferred amount of plasticizer is 0.2 to 8 parts by weight, more preferably 0.2 to 5 parts by weight.

In the present invention, the blending amount of benzotriazole and/or its derivative is 0.1 to 5 parts by weight because if it is less than 0.1 part by weight, an excellent rust-preventing film cannot be formed regardless of the plasticizer content. Anti-rust effect cannot be expected. On the other hand, if it exceeds 5 parts by weight, the rust prevention effect will be saturated,
This is not desirable because it lacks economic efficiency. The preferred amount of the rust preventive is 0.2 to 3 parts by weight, more preferably 0.3 to 2 parts by weight.

A mixture of a polyester plasticizer in which benzotriazole and the like described above are dissolved in an olefin resin base material is extruded and coated onto stranded copper wire, and then an olefin resin insulator is extruded and coated on the coating for outdoor use. When used as an insulated wire, the polyester plasticizer containing benzotriazole, etc., blended into the olefin resin base material rapidly blooms on the entire surface of the copper strands of the hard copper stranded wire, creating a stable bond with the anti-rust component on the copper surface. In addition, a protective film made of a water-repellent polyester plasticizer containing benzotriazole or the like is formed on the outer periphery of the rust-preventive film. After that, even if the copper base is exposed on the hard copper stranded wire, a rust-preventing film is formed to repair it, so that the hard copper stranded wire is protected against corrosive rainwater that enters the inside of the outdoor insulated wire through small gaps. Even if the hard copper stranded wire is immersed in water, the double coating of benzotriazole and protective coating formed on the entire surface of the hard copper stranded wire can completely prevent oxidation or corrosion of the copper wire. This makes it possible to prevent stress corrosion cracking.

〔Example〕

Examples and comparative examples of the present invention will be described below.

After concentrically twisting 19 hard copper strands with an outer diameter of 2 mmφ, an olefin resin mixture containing a polyester plasticizer, benzotriazole, etc. shown in Table 1 was applied to the hard copper strands using a tandem extruder. A 60 mm" outdoor polyethylene insulated wire was manufactured by press-fitting the insulation to a thickness of 0.5 mm, and then extruding and covering the outer periphery with a polyethylene insulator having an insulation thickness of 2.0 mm. The following corrosion resistance tests (Note 1, Note 2) were conducted on the electric wires.

The results are shown in the bottom row of Table 1.

(Note 1) Cut a 10 cm long sample from an outdoor polyethylene insulated wire that has been manufactured for 10 days using a hacksaw, peel off the insulator, take out the hard copper strands, and remove the oil that adheres to the surface of the conductor element wire. After washing it off with a solvent, it was immersed in a sodium sulfide aqueous solution with a concentration of 1100 pp for 30 seconds at room temperature, and then taken out, and the discolored state of the surface of the conductor strand was visually observed to judge whether the corrosion resistance was good or bad. The evaluation criteria were as follows: ◯ indicates no discoloration, Δ indicates discoloration in some places, and X indicates clear black discoloration.

(Note 2) A 30 cm long sample was cut from an outdoor polyethylene insulated wire that had been manufactured for 10 days using a hacksaw, and 1/2 of the sample was immersed in an aqueous ammonia solution with a concentration of 1100 pp.
After being immersed in a corrosive environment for 8 weeks with a heat cycle of 8 hours at °C and 16 hours at room temperature and replaced with fresh ammonia solution, the sample is removed and the insulator is peeled off to form on the conductor. Visually check the discoloration of copper oxide,
The corrosion resistance was judged. The judgment criteria are the same as (Note 1).

As can be seen from the results, Examples 1 to 6 show good results in all tests, but in Comparative Example 1, the amount of polyester plasticizer blended is small, so the plume of plasticizer is small, and the stranded wire 19 A sufficient corrosion-resistant film is not formed on the surface of the seven copper wires in the main twisted inner layer. In Comparative Example 2, since no polyester plasticizer was blended, a sufficient corrosion-resistant film could not be formed even if an appropriate benzotriazole was blended. In Comparative Example 3, even if the polyester plasticizer and benzotriazole were blended, if the blended amount of benzotriazole was not appropriate, a sufficient corrosion-resistant film would not be formed, which is not preferable.

Regarding the corrosion resistance test (Note 1), in Examples 1 to 6, a corrosion-resistant film with copper was formed well, and it is considered that the films are resistant to corrosive environments.

Next, in place of the polyethylene insulator used for the outer cover shown in the above example, a polyethylene insulator mixed with a crosslinking agent (DCP) was used in the same manner as in the example, and a known crosslinking device was used to make it suitable for outdoor use. A cross-linked polyethylene insulated wire was manufactured. The results of the corrosion resistance test (Note 1, Note 2) were the same as in Table 1.

Furthermore, in the above example, benzotriazole and/or benzotriazole derivatives were dissolved in an alcoholic solvent such as methanol or isopropyl alcohol based on 100 parts by weight of the olefinic resin, and the solution was poured into a polyester plasticizer. A polyester plasticizer containing benzotriazole and the like was blended with a white powder filler such as calcium carbonate and clay, and the blend was mixed with 100 parts by weight of an olefin resin. On the other hand, an olefin resin mixture containing a plasticizer, benzotriazole, etc. in the amounts specified in the present invention can be used by coating a hard copper stranded wire in the same manner as in the examples.

〔Effect of the invention〕

As explained above, in the outdoor polyethylene insulated electric wire and crosslinked polyethylene electric wire according to the present invention, a polyester plasticizer containing benzotriazole etc. blended into the olefin resin base material is applied to the entire surface of the copper strands of the hard copper stranded wire. It blooms to form a stable rust-preventing film on the copper surface with rust-preventing ingredients, and a protective film made of a water-repellent polyester plasticizer containing benzotriazole is formed on the outer periphery of the copper surface, so corrosive rainwater can It shows good corrosion resistance even if it penetrates into the interior, and is highly effective in preventing stress corrosion disconnection accidents that occur in this type of insulated wire.

Claims (1)

[Claims] On the copper conductor, for 100 parts by weight of olefin resin,
0.05 to 10 parts by weight of polyester plasticizer, 0.05 to 10 parts by weight of benzotriazole and/or benzotriazole derivative.
1. An outdoor insulated wire, characterized in that the mixture is extrusion coated in an amount of 1 to 5 parts by weight, and an olefin resin insulator is extrusion coated on the coating.