JPH02148624A - Manufacture of insulating cable - Google Patents

Abstract

PURPOSE:To obtain an insulating cable keeping copper color for a long period and having a satisfactory adhesion between an insulator and a hard copper stranded wire by applying a rust preventive solution to the hard copper stranded wire. CONSTITUTION:A rust preventive solution consisting of 0.1-10wt.% of benzotriazole or/and benzotriazole derivative, 0.2-10wt.% of a polyester plasticizer, and the remaining of a solvent is applied to the surface of a hard copper stranded wire, and then an insulating coating layer is formed on the outer circumference of the resulting hard copper stranded wire. Before coating of the insulator, the rust preventive solution having the polyester plasticizer addition amount reduced to 0-0.5wt.% is applied to the copper element wire made in contact with the insulator. Hence, an insulating cable having an excellent adhesion with the upper stranded copper element wire contacting with the insulator and excellent anti-corrosive film and protective film on the stranded conductor can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing insulated wires and power cables in which discoloration of the surface of stranded copper wires is prevented for a long period of time using a benzotriazole anticorrosion solution.

[Conventional technology]

Conventionally, during the storage of copper wires and copper stranded wires, or during the manufacturing process of insulated wires, and during the storage of wires, the surfaces of copper wires and stranded wire conductors may discolor. , copper stranded wires, etc. are coated with an anti-rust solution for copper.

On the other hand, vinyl chloride insulated wire (OW) is used as an outdoor distribution line.
, polyethylene insulated wire (OR), cross-linked polyethylene insulated wire (OC), etc. are often used, but a black copper oxide film forms on the surface of the copper wire several years after wiring, and in rare cases, hard copper stranded wire becomes knife-like. Abnormal disconnection in the shape of a cut, so-called stress corrosion cracking, may occur, which is an important problem in terms of power safety.

This stress corrosion cracking occurs when rainwater enters the wire from the terminal and accumulates in the wire's voids, condenses and becomes corrosive water that forms a thick black copper oxide film on the surface of the copper wire. The corrosion factor selectively dissolves the base copper exposed in the parts, and the stress factor such as the bending stress that occurs when processing hard V7A stranded wire and the stress that occurs when overhead wires resist the bending stress that occurs when winding the wire in a drum. It is said to occur through interaction.

To prevent stress corrosion cracking that occurs in such long-term corrosive environments, applying a solution of benzotriazole dissolved in a volatile solvent such as alcohol alone to hard copper strands does not form a sufficient corrosion-resistant film. Therefore, long-term corrosion resistance cannot be expected, and there is a problem of stress corrosion cracking.

Therefore, the following solutions are available: ■ Using an insulating layer containing a copper-phase rust-preventing component, ■ Filling a watertight compound into hard copper twisted cotton, and ■ Dissolving benzotriazole derivatives in liquid paraffin, polybutene, silicone oil, etc. A method of coating stranded copper wire on hard copper strands has been proposed.

However, 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 copper for a long period of time, and there is an undesirable problem that the insulation resistance of the insulating layer is reduced. As for (2), there are problems in that the manufacturing cost is high, the removal work of the watertight compound is troublesome, and if the removal is not sufficient, the current conduction characteristics of the connection part are deteriorated. Regarding ■, the adhesion between the insulator and the hard copper strands decreases due to its use.
There is a problem that the pull-out strength is insufficient.

[Problem that the invention seeks to solve]

The present inventors previously disclosed in Japanese Patent Application No. 63-37221 that a rust-preventing solution in which specific amounts of benzotriazole or/and a benzotriazole derivative and a polyester plasticizer were dissolved in a solvent was applied to stranded hard copper wire. , then filed an application for a manufacturing method for insulated wire that covers an insulator, but found that it was not always possible to satisfy the strict conductor pull-out test that evaluates the adhesion between the insulator and hard copper strands when wiring the insulated wire. Understood.

The present invention was made in view of the above problems, and by applying an anti-corrosion solution to the hard copper stranded wire, a strong corrosion-resistant film is formed on the surface of the copper wire or the hard copper stranded wire. Even if corrosive rainwater enters the stranded wire, it maintains its copper color for a long time.
Another object of the present invention is to provide a method for producing an insulated wire and a power cable that have good adhesion between an insulator and a hard copper strand.

[Means for solving problems]

The structure of the present invention is such that a rust preventive solution consisting of 0.1 to 10% by weight of benzotriazole or/and a benzotriazole derivative, 0.2 to 10% by weight of a polyester plasticizer, and the balance being a solvent is applied to the surface of the hard copper stranded wire. In the method of forming an insulating coating layer on the outer periphery of the hard copper stranded wire after coating, a polyester plasticizer is added to the copper wire in contact with the insulator in an amount of 0 to 0.5 weight before coating the insulator. %.

Hereinafter, the configuration of the present invention will be explained in more detail.

The reason why benzotriazole is added in an amount of 0.1 to 10% by weight in the rust preventive solution used in the present invention is that even if 10% by weight or more is added, a corrosion-resistant film is not formed any further, so the rust preventive effect is reduced. Saturation is reached and excessive amounts lead to precipitation, which is undesirable.

On the other hand, if the amount added is less than 0.1% by weight, a sufficient corrosion-resistant film will not be formed, and therefore no rust-preventing effect will be obtained. The preferred amount of benzotriazole added is 1 to 5% by weight.

The reason why the amount of the polyester plasticizer used is 0.2 to 10% by weight is that if it is more than 10% by weight, stickiness remains on the stranded conductor after application and the conductor pullout test is not preferable. On the other hand, if it is less than 0.1% by weight, it is difficult to obtain a sufficient rust-preventing effect because the protective effect on the corrosion-resistant film that is formed is lacking.

Next, in the configuration of the present invention, before coating the one-color frame, the amount of polyester plasticizer added to the copper wire in contact with the insulator is 0 to 0.
．． For example, applying a rust preventive solution with a concentration of 5% by weight is 19
In the manufacturing process of this hard copper concentric stranded wire, when a rust preventive solution containing a large amount of polyester plasticizer is applied to the center wire, 6 ply-stranded wires, and 12 ply-twisted wires, 12 Since a thick protective film of polyester plasticizer remains on the surface of the wire, applying an insulator is not preferable because the adhesion between the insulator and the hard copper stranded wire decreases. Therefore, before coating the hard copper stranded wire with the insulator, apply an appropriately selected anti-rust solution containing a polyester plasticizer of 0 to 0.5% by weight, quickly dry it, and apply it to the insulator. The thickness of the protective film of polyester plasticizer remaining on the real twisted wire is thinned.
The hard copper stranded wire is modified to be in a good state, and furthermore, corrosion resistance is imparted to improve the adhesion between the insulator and the hard copper stranded wire.

In addition, in the production of hard copper concentric stranded wires, if the amount of polyester plasticizer in the rust preventive solution to be applied is close to the lower limit, the amount of polyester plasticizer should be reduced to 0.5 before coating the insulator. % by weight of a rust preventive solution is applied onto the ply-stranded strands to complement the rust preventive film and provide a protective film with a polyester plasticizer to ensure excellent corrosion resistance.

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.

The solvent used is used to facilitate the dissolution and mixing of benzotriazole or/and benzotriazole derivative and the polyester plasticizer, and to adjust the stickiness of the polyester plasticizer.
Alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and trichloroethane are preferred, but are not particularly limited.

In addition to Henztriazole, the present invention also uses benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, methylbenzotriazole cyclohexylamine salt, etc. Benzotriazole derivatives can also be used.

[For production]

Outdoor insulated wires break due to stress corrosion cracking.
After the insulated wire is installed on the overhead line, corrosive rainwater enters the twisted space of the hard copper strands inside the wire through small gaps such as the tie-down section, terminal section, or connection section, causing corrosion that accumulates over a long period of time. Factors are of primary importance. Therefore, the requirements for an outdoor insulated wire are excellent corrosion resistance and good adhesion between the insulator and the copper wire in contact with the conductor pull-out test, which can be conducted under severe conditions during overhead wiring.

Rust preventive solution used in the present invention, i.e. benzotriazole or/and benzotriazole derivative 0.1 to 10
When a rust preventive solution consisting of 0.2 to 10 wt% polyester plasticizer and alcohol with the remainder being a solvent is applied to the surface of a hard copper stranded wire, in the presence of the alcohol, the rust preventive component appears on the copper surface. When a rust-preventive film is well formed by the chelate bond of improves.

However, the amount of polyester plasticizer added in the anti-corrosion solution is large, and after application, the film of polyester plasticizer that remains on the copper wire in contact with the insulator is so thick that when it is made into an insulated wire, the insulator and hard copper This is undesirable because the adhesion with the stranded wires decreases and the insulator is pulled out during overhead wire installation.

In the manufacturing method of the present invention, → in the manufacturing process of the copper stranded wire, a rust-preventing solution of a specific composition to be used is applied to each copper wire to prevent rust, and the copper wire in contact with the insulator is Even if there is some residual polyester plasticizer film, reduce the amount of polyester plasticizer added before coating the insulator.
Appropriately select a rust preventive solution containing ~0.5% by weight, apply it on the copper wire in contact with the insulator, and quickly dry it to adjust the stickiness and uniformity of the polyester plasticizer film that remains on the copper wire. Since this is carried out and the anti-rust coating on the copper wire is simultaneously applied, it is suitable for severe corrosion resistance and conductor pullout tests, and can prevent stress corrosion and disconnection.

〔Example〕

Hereinafter, examples according to the present invention and comparative examples will be explained in comparison.

When concentrically twisting 19 hard copper strands with an outer diameter of 2.0 mmφ and covering the outer periphery with polyethylene insulation,
In advance, apply anti-corrosion solutions of the respective compositions shown in Table 1 to the surface of the central strand, 6 pre-twisted copper strands, 12 pre-twisted copper strands, and the copper strands in contact with the insulator before insulation coating. . For example, the application of the central strand, 6 pre-twisted strands, and 12 pre-twisted strands is carried out by feeding a fixed amount of anti-rust solution with a micro pump and passing it through a rust-preventing tank equipped with an air wiper. ,
The coating on the surface of the copper wire in contact with the insulator is carried out by wrapping a weighted felt around the stranded wire, pumping a fixed amount of anti-corrosion solution onto the upper end of the wire using a micro pump, and passing it through a hot air dryer to quickly dry it.

Subsequently, a polyethylene insulator is extruded and coated on the outer periphery.
0 mm" outdoor polyethylene insulated wires were manufactured. Each of the obtained insulated wires was subjected to the corrosion resistance test (
Note 1, Note 2, Note 3) and induced pull-out test (Note 4) were conducted. The results are shown in the bottom row of Table 1.

(Note 1) Cut a 10 cm long sample from an insulated wire with a hacksaw, remove the insulator, and immerse the conductor wire in a sodium sulfide aqueous solution with a concentration of 100 ppn+ for 30 seconds at room temperature, then take it out and check for discoloration on the surface of the conductor wire. The condition was visually observed to determine whether the corrosion resistance was good or bad.

(Note 2) After cutting a 10cm+ length sample from the insulated wire with a hacksaw, peeling off the insulator and taking out the hard copper strands, and washing off the anti-rust solution adhering to the surface of the conductor wire with a solvent, After being immersed in a sodium sulfide aqueous solution with a concentration of 1100 pp for 30 seconds at room temperature, the wire was taken out, and the discolored state of the surface of the conductor wire was visually observed to determine whether the corrosion resistance was good or bad.

Regarding the evaluation criteria for (Note 1) and (Note 2), an O mark indicates no discoloration, a Δ mark indicates a slight discoloration, and an X mark indicates a clear discoloration.

(Note 3) Cut a 30cm long sample from an insulated wire with a hacksaw, and add it to a 1/1/2 ammonia aqueous solution with a concentration of 1100pp.
After being immersed in a corrosive environment for 8 weeks, the sample was taken out and the insulator was peeled off. The average thickness of the copper oxide formed on the conductor was determined, and the corrosion resistance was judged from that value.

The evaluation criteria were as follows: O mark indicates that the film thickness is less than 0.2 μm, Δ mark indicates that the film thickness is in the range of 0.2 to 0.3 μm, and X mark indicates that the film thickness exceeds 0.3 μm.

(Note 4) Cut a 3m long sample from an insulated wire with a hacksaw.
Peel off 10 cm of the insulator at one end of the 0.3 m end, fix the other end, and apply a load of 1 ton (pulling load) to the insulator at one end. Observe how the insulator is pulled out. A judgment was made as to whether the adhesion was good or bad.

The evaluation criteria were as follows: ◯ marks are difficult to pull out, Δ marks are slightly pullable, and X marks are large.

As can be seen from the results, Examples 1 to 5 show good results in all tests, but Comparative Examples 1 and 2 correspond to Examples 1 and 3, and the ply-twisted copper in contact with the insulator Because no anti-rust solution was applied to the wires before insulation,
Although it has corrosion resistance, the adhesion between the conductor and the insulator deteriorates, making conductor pullout tests undesirable. In Comparative Example 3, since the amount of pendutriazole added was small, a sufficient corrosion-resistant film was not formed on the copper surface, which is not preferable. In Comparative Example 4, the amount of polyester plasticizer added in the antirust solution applied to the copper wire was not appropriate, so the corrosion resistance test was not preferable because the protective film on the antirust film was lacking.

〔Effect of the invention〕

As explained above, according to the manufacturing method according to the present invention,
Traditionally, vA Enden Wire has been used in the production of electric cables because it provides an insulated wire that has good adhesion to the ply-stranded copper wire in contact with the insulator and has an excellent corrosion-resistant film and protective film on the stranded conductor. It is possible to sufficiently prevent the problem of discoloration of stranded wire conductors during the process and during wire storage, and even if corrosive rainwater enters from the terminals after being installed as outdoor insulated wires, stress corrosion cracking can be prevented. The effect is great because there is no need to worry about it.

Claims (1)

[Claims] After applying a rust preventive solution consisting of 0.1 to 10% by weight of benzotriazole or/and benzotriazole derivative, 0.2 to 10% by weight of polyester plasticizer, and the balance being a solvent to the surface of the hard copper stranded wire, In the method of forming an insulating coating layer on the outer circumference of stranded steel wire, zero amount of polyester plasticizer is added to the copper wire in contact with the insulator before coating the insulator.
A method for manufacturing an insulated wire, comprising applying a rust preventive solution of ~0.5% by weight.