JPH0266806A - Insulation cable for outdoor use - Google Patents

Abstract

PURPOSE:To prevent stress corrosion breaking of wires due to corrosive rain drops by extruding a mixture obtained by adding the predetermined amounts of epoxy plasticizer, benzotriazol and/or a benzotriazol derivative to an olefin resin to cover a copper conductor. CONSTITUTION:A mixture of 0.05 to 10 weight parts of an epoxy plasticizer and 0.1 to 5 weight parts of benzotriazol and/or a 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 epoxidized unsaturated fat and oil such as soybean oil, epoxidized linseed oil, epoxidized castor oil and others, epoxidized linseed oil and fat acid butyl, octylepoxy stealate, epoxy butyl stealate, epoxidized fat acid monoester, epoxidized olein acid octylester, epoxidized olein acid decylester, epoxy monoester, alkyl epoxy stealate and the like as the epoxy 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. 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 by applying the commercial rust preventive composition previously filed in Japanese Patent Application No. 63-20269 onto copper wire or stranded copper wire, a strong rust preventive film can 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-mentioned commercial rust preventive composition, 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.

[Failure to solve the problem]

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 an epoxy plasticizer and 0.1 to 5 parts by weight of benzotriazole and/or benzotriazole derivatives 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 epoxy plasticizers used in the present invention include epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized unsaturated oils and fats such as epoxidized oils, epoxidized butyl linseed oil fatty acids, and octyl epoxy steer. rate,
Epoxidation of epoxybutyl stearate, epoxidized fatty acid monoester, epoxidized oleate octyl ester, epoxidized oleate decyl ester, epoxy monoester, alkyl epoxy stearate, n-alkyl epoxy stearate, isoalkyl epoxy stearate, etc. Unsaturated fatty acid esters, epoxycyclohexane derivatives such as di-2-ethylhexyl epoxy hexahydrophthalate, diisodecyl epoxy hexahydrophthalate, cycloalkyl epoxy stearate, and epichlorohydrin derivatives, and one or more of these groups are used. can.

In addition to benzotriazole, examples of the copper phase rust preventive used in the present invention include benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, henstriazole cyclohexylamine salt, benzotriazole morpholine salt, henzotriazole diisopropylamine salt, and methyl benzotriazole. Hensitriazole derivatives such as triazole cyclohexylamine salts can also be used in the same amount as hensitriazole.

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

In the present invention, 0.05 to 10 parts by weight of epoxy plasticizer is blended with 100 parts by weight of olefin resin, and if it is less than 0.05 parts by weight, regardless of the addition of rust preventive,
Excellent rust prevention effect cannot be expected. 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. No rust prevention effect can 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 an olefin resin base material and an epoxy plasticizer in which benzotriazole, etc., as described above is dissolved, is extruded and coated onto stranded copper wire, and an olefin resin insulator is extruded and coated on the coating for outdoor use. When used as an insulated wire, the epoxy plasticizer containing benzotriazole, etc., blended into the olefin resin base material rapidly blooms on the entire surface of the copper wire of the hard copper stranded wire, and stabilizes the copper surface with anti-rust components. In addition, a protective film made of a water-repellent epoxy 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+nmφ, an olefin resin mixture containing an epoxy plasticizer and benzotriazole shown in Table 1 was applied to the hard copper strands using a tandem extruder. A press-fit coating is applied to a thickness of 0.5 mm+, and an insulating layer of a thickness of 2.0 mm is attached to the outer periphery. A 60mm" outdoor polyethylene insulated wire was manufactured by extrusion coating Ovn's polyethylene insulator. Each of the obtained outdoor polyethylene insulated wires was subjected to the following corrosion resistance test (Note 1,
Note 2) was carried out.

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 × indicates clear black discoloration.

(Note 2) A 30cm long sample was cut from an outdoor polyethylene insulated wire that had been manufactured for 10 days using a hacksaw, and then immersed in an ammonia aqueous solution with a concentration of 1100pp for 172 hours.
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 epoxy plasticizer blended is small, so there is little bloom of the plasticizer, and the stranded wire 19 Surface G of the seven copper wires in the real twisted inner layer = no sufficient corrosion-resistant film is formed. In Comparative Example 2, since no epoxy 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 epoxy 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 carried out in the same manner as in the example, and outdoors using a known crosslinking device. 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.

In addition, 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 olefin resin, and the solution was poured into an epoxy plasticizer. An olefin resin mixture containing a specific amount was used, but an epoxy 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 olefin resin 10
An olefin resin mixture containing a plasticizer, benzotriazole, etc. in the amounts specified in the present invention based on 0 parts by weight 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 wire and crosslinked polyethylene wire according to the present invention, the epoxy 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. Plumes and forms a stable anti-rust film with anti-rust components on the copper surface,
Furthermore, a protective film made of a water-repellent epoxy plasticizer containing benzotriazole is formed on the outer periphery, so even if corrosive rainwater penetrates inside the wire, it exhibits good corrosion resistance.
This 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 epoxy plasticizer, 0.1 to 10 parts of benzotriazole and/or benzotriazole derivative
A mixture containing 5 parts by weight was extrusion coated, and on the coating,
An outdoor insulated wire characterized by being made of an extrusion coated olefin resin insulator.