JPH02148622A - 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. In this case, the addition amount of the polyester plasticizer is successively reduced from the center of the stranded conductor toward the direction contacting with the insulator. Before coating of the insulator, the polyester plasticizer addition amount in the rust preventive solution applied to the copper element wire made in contact with the insulator is made 0-0.3wt.%. 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 protection solution is applied to copper stranded wires, etc.

On the other hand, vinyl chloride insulated wire (OW) is used as an outdoor distribution line.
, polyethylene insulated wires (OE), cross-linked polyethylene insulated wires (OC), etc. are often used, but a black copper oxide film forms on the surface of the m-wires several years after the wiring is completed, and in rare cases, hard copper stranded wires become 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, causing cracks in the film. The corrosion factor that selectively melts the underlying copper exposed in the parts, and the stress factor such as the bending stress that occurs when processing hard copper strands and the stress that occurs when overhead wires are used against 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, as a solution, ■ a method of using an insulating layer to which a copper-phase rust-preventive component is added, ■ a method of filling a watertight compound into hard copper strands, and ■ a method of dissolving benzotriazole derivatives in liquid paraffin, polybutene, silicone oil, etc. A method has been proposed in which the material is coated on hard copper stranded wire.

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 the steel 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 preventive solution containing benzotriazole or/and a benzotriazole derivative and a polyester plasticizer dissolved in a solvent was prepared using hard copper t. 8. Although we applied for a manufacturing method for insulated wire that coats the wire and then coats it with an insulator, it is not always possible to conduct a rigorous conductor pull test to evaluate the adhesion between the insulator and the hard copper strands when wiring the insulated wire. I found that I was not satisfied.

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 IO weight % of benzotriazole or/and benzotriazole derivative, 0.2 to 10 weight % of a polyester plasticizer, and the balance being a solvent is applied to the surface of the hard copper stranded wire. After coating, in the method of forming an insulating coating layer on the outer periphery of the stranded hard copper wire, the amount of polyester plasticizer added is gradually decreased from the center of the stranded conductor in the direction of contact with the insulator to coat the insulator. The amount of polyester plasticizer added to the antirust solution applied to the copper wire in contact with the insulator is 0 to 0.3% by weight.

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

In the rust preventive solution used in the present invention, the amount of benzotriazole added is o, 1-io wt% because even if it is added in an amount of 10 wt% or more, a corrosion-resistant film is not formed. Saturation is reached and excessive amounts lead to precipitation, which is undesirable.

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

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

Next, in the configuration of the present invention, the amount of polyester plasticizer added is gradually decreased from the center of the twisted conductor toward the direction of contact with the insulator, and the amount of polyester plasticizer is applied to the copper wire in contact with the insulator before coating the insulator. The amount of polyester plasticizer added in the anti-corrosion solution was reduced to 0.
The reason why the concentration is ~0.3% by weight is that during the manufacturing process of 19 hard copper concentric strands, the center strand and 6 pre-twisted strands were treated with a rust preventive solution containing a large amount of polyester plasticizer. A rust preventive solution containing less polyester plasticizer than the former is applied to the ply-twisted wire, and when coating the insulator on the hard copper strands after application, the amount of polyester plasticizer added is 0 to 0.
Apply an appropriately selected anti-corrosion solution containing 0.3% by weight and dry quickly to reduce the thickness of the protective film of the polyester plasticizer remaining on the 12 twisted wires in contact with the insulator. When coated, it becomes an insulator and hard! This is because the adhesion to the rI stranded wire can be improved, and an insulated wire with excellent corrosion resistance and suitable for wiring can be obtained.

In this case, if the center strand, the first stranded strands, and the first stranded strands are coated with a rust preventive solution containing an intermediate amount of the polyester plasticizer shown in the present invention from the specified upper limit, the insulation Since a thick protective film of polyester plasticizer remains on the surface of the 12 ply twisted wires that come into contact with the body, applying an insulator is not preferable because the adhesion between the insulator and the hard copper strands decreases. Therefore, we applied an anti-corrosion solution that does not contain polyester plasticizer to reduce the thickness of the protective film of polyester plasticizer remaining on the 12 twisted wires, thereby further imparting corrosion resistance. to improve the adhesion between the insulator and the hard copper stranded wire.

Next, in the case of seven hard copper concentric strands, since it is composed of a center strand and six top-twisted strands, polyester plasticizer is applied from the center of the stranded conductor in the direction of contact with the insulator. It is possible to reduce the amount of the anti-rust solution and apply it, but as an alternative method, if the protective film of the polyester plasticizer remaining on the ply-stranded wire becomes thicker by applying one kind of anti-corrosion solution, it is possible to reduce the amount of the anti-corrosion solution. The amount of polyester plasticizer added to the antirust solution applied to the copper wire can be 0 to 0.5% by weight to improve the adhesion between the insulator and the hard copper stranded wire. . For the 19 hard copper concentric strands, if the protective film of the polyester plasticizer remaining on the ply-stranded strands becomes thicker due to the application of one type of anti-rust solution, apply the same method as for the 7 concentric strands described above. This can improve the adhesion between the insulator and the hard copper stranded wire.

The polyester plasticizer used in the present invention includes adipic acid polyester, sepacic 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, and isopropyl alcohol and trichloroethane are preferred, but are not particularly limited.

In addition to benzotriazole, the present invention uses benzotriazoles such as benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, and methylbenzotriazole cyclohexylamine salt. Derivatives can also be used.

[For production]

The reason why outdoor WA edge wires break due to stress corrosion cracking is that after the insulated wires have been installed, the hard copper strands inside the wires are inserted into the stranded voids through small gaps such as at the anchorage, terminals, or connections. The primary cause of corrosion is the intrusion of corrosive rainwater and the accumulation of water in ditches over a long period of time. Therefore, the requirements for an outdoor insulated wire are excellent corrosion resistance and good adhesion to the copper wire in contact with the VA recording body, which can be used in severe conductor pull-out tests during overhead wiring.

Rust preventive solution used in the present invention, i.e. benzotriazole or/and benzotriazole derivative 0.1-10
When a rust preventive solution consisting of 0.2 to 10 wt% polyester plasticizer and alcohol, the balance being a solvent, is applied to the surface of a hard copper stranded wire, in the presence of 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 the thicker the film of polyester plasticizer that remains on the copper wire in contact with the insulator after application, the more likely it is that the insulator and hard copper strands will be separated when used as an insulated wire. The adhesion with the wire will deteriorate, and the insulator will be pulled out during overhead wire installation, which is not desirable.

In the manufacturing method of the present invention, during the manufacturing process of the hard copper stranded wire used, a rust-preventing solution containing a polyester plasticizer is applied to the copper wire in a manner that gradually reduces the amount of polyester plasticizer added from the center of the stranded conductor in the direction of contact with the insulator. Apply anti-corrosion treatment and before covering the insulator, apply a rust-preventive solution containing 0 to 0.3% by weight of polyester plasticizer on the copper wire in contact with the insulator and dry quickly. In this way, the stickiness of the polyester plasticizer film left on the copper wire is adjusted and made uniform, and the anti-corrosion film on the copper wire is simultaneously supplemented, making it possible to conduct rigorous corrosion resistance and conductor pull-out tests. This makes it possible to 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.
0o+m" outdoor polyethylene insulated wires were manufactured. Each of the obtained insulated wires was subjected to corrosion resistance tests (Note 1, Note 2, Note 3) and induction pullout tests (Note 4) as described below. The results are as follows. It is shown in the lower row of Table 1.

(Note 1) Cut a sample of loc+n length from the insulated wire with a hacksaw, and remove the conductor wire from which the insulator has been stripped off by immersing it in a sodium sulfide aqueous solution with a concentration of 1100 pp for 30 seconds at room temperature. The condition was visually observed to determine whether the corrosion resistance was good or bad.

(Note 2) After cutting a 10 cs 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, Concentration 1
After being immersed in a 100 pp sodium sulfide aqueous solution at room temperature for 30 seconds, it was taken out, and the discoloration state of the surface of the conductor wire was visually observed to determine whether the corrosion resistance was good or bad.

The evaluation criteria for (Note 1) and (Note 2) were as follows: ○ indicates no discoloration, Δ indicates slight discoloration, and X indicates clear discoloration.

(Note 3) Cut a 30 cm long sample from an insulated wire with a hacksaw, and add it to an ammonia aqueous solution with a concentration of 1100 pp.
After being immersed in a corrosive environment for 8 weeks, the sample was removed, the insulator was stripped off, and the conductor was removed. The average and film thickness of the copper oxide formed on the surface were determined, and the quality of the corrosion resistance was determined based on the values.

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 and compare the conductor and insulator. The adhesion was judged to be good or bad.

The evaluation criteria were as follows: ◯ mark indicates that it is difficult to pull out, Δ mark indicates that it can be pulled out slightly, and X mark indicates that it pulls out significantly.

As can be seen from the results, Examples 1 to 5 showed good results in all tests, but in Comparative Example 1, an anti-rust solution was applied to the ply-twisted copper wire in contact with the insulator before insulation. Therefore, although the conductor has corrosion resistance, the adhesion between the conductor and the insulator deteriorates, making the conductor pullout test undesirable. In Comparative Example 2, the polyester plasticizer film remaining on the ply-stranded copper wire was thick, but the amount of polyester plasticizer added in the anti-corrosion solution applied before insulation was not appropriate, so the contact between the conductor and the insulator was Adhesion deteriorates, making conductor pullout tests unfavorable. In Comparative Example 3, since the amount of benzotriazole added was small, a sufficient corrosion-resistant film was not formed on the copper surface, which is not preferable.

In Comparative Example 4, the polyester plasticizer film remaining on the ply-twisted copper wire was thick at the edges, so even if a rust preventive solution containing no polyester plasticizer was applied before insulation, the film remained on the ply-twisted copper wire. The stickiness adjustment and uniformity of the polyester plasticizer film that is left in the film becomes insufficient, making the conductor pullout test unfavorable. In Comparative Example 5, the corrosion resistance test was not preferable because the amount of polyester plasticizer added in the antirust solution applied to the center line, first-twisted, and first-twisted copper wires was not appropriate.

[Effect of the invention] As explained above, according to the manufacturing method according to the present invention,
Since it is possible to obtain 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 wire conductor, it has been conventionally used during the manufacturing process of insulated wires or power cables. Moreover, it is possible to sufficiently prevent the problem of discoloration of the hot wire conductor during storage of electric wires, and even if corrosive rainwater enters from the terminals after being installed as outdoor insulated electric wires, stress corrosion cracking will not occur. There is no need to worry, so the effect is great.

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 around the outer circumference of stranded copper wire, the amount of polyester plasticizer added is gradually decreased from the center of the stranded conductor in the direction of contact with the insulator, and the amount of polyester plasticizer added is gradually reduced from the center of the stranded conductor in the direction of contact with the insulator. A method for manufacturing an insulated wire, characterized in that the amount of polyester plasticizer added in the antirust solution applied to the copper wire in contact with the copper wire is 0 to 0.3% by weight.