JPH02181317A - Manufacture of insulated electric cable - Google Patents

Abstract

PURPOSE:To obtain an insulated electric cable having a highly corrosion- resistant coating on a twisted conductor by applying a rust preventing solution containing 0-20wt.% of phosphoric acid-based plastisizer to the copper strand which contacts with an insulator before the cable is coated with an insulator. CONSTITUTION:Rust preventing treatment is carried out by applying a rust preventing solution on a copper strand while the addition amount of a phosphoric acid-based plastisizer being decreased gradually toward the direction from the center of the twisted cable to an insulator to be contacted. Then, before coated with an insulator, the copper strand to have a contact with the insulator is coated with a rust preventing solution containing 0-20wt.% of a phthalic acid-based plastisizer and dried so as to adjust and uniformalize the viscosity of the phosphoric acid-based plastisizer remaining on the copper strand. And at the same time, the rust preventing film on the copper strand is complemented. By this method, a sufficiently corrosion-resistant coating is formed.

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 tJA 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 are coated with anti-copper W4 solution.

On the other hand, vinyl chloride insulated wire (OW) is used as an outdoor distribution line.
, polyethylene insulated wire (OE), cross-linked polyethylene 'vA rim wire (OC), etc. are often used, but a black copper oxide film forms on the surface of the copper wire several years after the wire is installed, and in rare cases, hard copper stranded wire abnormally disconnects in a knife-cut pattern, so-called
Stress corrosion cracking can 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 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, we added a copper phase anti-rust component.
Proposed methods include using an A-edge layer, ■ filling the hard copper strands with a watertight compound, and ■ coating the hard copper strands with a benzotriazole derivative dissolved in liquid paraffin, polybutene, silicone oil, etc. has been done.

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 ■, its use reduces the adhesion between the insulator and the hard copper stranded wire.
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. 63-45278 that a rust preventive solution in which specific amounts of benzotriazole or/and a benzotriazole derivative and a phosphoric acid plasticizer were dissolved in a solvent was applied to hard W4 stranded wire. However, the application was filed regarding a method for manufacturing insulated wires that cover an insulator; however, when wiring insulated wires, the strict conductor pull-out test to evaluate the adhesion between the insulator and the hard copper strands was not always satisfactory. I understand.

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]

As a result of intensive studies to solve the above problem, the present inventors found that the amount of phosphoric acid plasticizer in the rust preventive solution applied to the copper wire in contact with the insulator is 40% by weight in order to be suitable for conductor drawing. %
The present invention was completed by discovering that this is at the critical point.

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, 2 to 70% by weight of a phosphoric acid carbonate, 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 hard copper stranded wire, the amount of the phosphoric acid plasticizer added is gradually decreased from the center of the dielectric toward the direction of contact with the insulator to coat the insulator. The amount of phosphoric acid plasticizer added in the anti-corrosion solution applied to the copper wire in contact with the insulator is reduced to 0.
It is applied at a concentration of ~20% by weight.

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 amount of phosphoric acid plasticizer used is 2 to 70% by weight because
If the weight is 70 weight or more, stickiness remains on the IW wire conductor after application and the conductor pullout test is not preferable. On the other hand, if the content is less than 2% by weight, the protective effect on the corrosion-resistant film formed is lacking, making it difficult to obtain a sufficient rust-preventing effect.

Next, in the configuration of the present invention, the amount of phosphoric acid plasticizer added is gradually decreased from the center of the dielectric toward the direction of contact with the insulator, and the amount of phosphoric acid plasticizer is applied to the copper wire in contact with the insulator before coating the insulator. The amount of phosphoric acid plasticizer added in the rust prevention solution is 0 to 20% by weight.
It is applied as 19 hard copper concentric strands,
The center strand and 6 first-stranded strands were coated with a rust-preventing solution containing a large amount of phosphoric acid plasticizer, and the 12 first-stranded strands were coated with a rust-preventing solution containing less phosphoric acid plasticizer. When coating the insulator on the coated hard copper strands, a rust preventive solution containing 0 to 20% by weight of a phosphoric acid plasticizer is applied and quickly dried to coat the insulator. By reducing the thickness of the protective film of the phosphoric acid plasticizer remaining on the 12 strands of stranded wire in contact with the insulator, the adhesion between the insulator and the hard copper strands can be improved, resulting in excellent corrosion resistance and cross-linking. This is because it can be used as an insulated wire suitable for.

In this case, a rust preventive solution containing an intermediate amount of the phosphoric acid plasticizer shown in the present invention from the specified upper limit is applied to the center strand, the first twisted strand, and the second stranded strand, respectively. A thick protective film of phosphoric acid plasticizer remains on the surface of the 12-strand ply-stranded wire in contact with the insulator, so applying an insulator will reduce the adhesion between the insulator and the hard copper strands, which is undesirable. . Therefore, we applied an anti-corrosion solution that does not contain phosphoric acid plasticizers.
The thickness of the protective film of phosphoric acid plasticizer remaining on the 12 twisted wires is modified to a thinner state, and further corrosion resistance is added to improve the adhesion between the insulator and the hard copper strands. Make it.

Next, in the case of seven hard copper concentric strands, since it is composed of a center strand and six top-twisted strands, the phosphoric acid plasticizer is It is possible to reduce the amount of the anti-corrosion solution in stages, but as an alternative, if the protective film of the phosphoric acid plasticizer remaining on the ply-stranded wire becomes thicker due to the application of one kind of anti-corrosion solution, it may cause the insulator to thicken. It is possible to improve the adhesion between the insulator and the hard copper strands by applying a phosphoric acid plasticizer in the rust preventive solution applied to the copper wires in contact with the copper wire in an amount of 0 to 20% by weight. . 19
For the hard copper concentric stranded wires, if the protective film of the phosphoric acid plasticizer remaining on the ply-stranded strands becomes thicker by applying one type of anti-corrosion solution, apply the same method as for the seven concentric stranded wires. This can improve the adhesion between the insulator and the hard copper stranded wire.

The phosphoric acid plasticizers used in the present invention include trimethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, tryptoxyethyl phosphate, triphenyl phosphate, and cresyl diphenyl.・Phosphate, isodecyl diphenyl phosphate, tricresyl phosphate, tritolyl ・
phosphates, tricylenyl phosphates, alkyl allyl phosphates, etc., and one or more of these groups can be used.

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

In addition to benzotriazole, the present invention uses benzotriazole derivatives such as benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, and methylbenzotriazole cyclohexylamine salt. 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. The cause is the primary meaning. 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 2 to 70 wt% phosphoric acid plasticizer and alcohol with the balance being a solvent is applied to the surface of a hard V;A stranded wire, the rust preventive component is applied to the copper surface in the presence of alcohol. A rust-preventive film is well formed by chelate bonding with
When the alcohol volatilizes, the contained phosphoric acid plasticizer forms a protective film on the rust preventive film, thereby enhancing the dual rust preventive effect and improving corrosion resistance.

However, the amount of phosphoric acid plasticizer added to the anti-corrosion solution is large, and the thicker the film of phosphoric acid plasticizer that remains on the copper wire in contact with the insulator after application, the harder it is to bond with the insulator when used as an insulated wire. The adhesion with the copper stranded wire decreases, and the insulator is pulled out during overhead wiring, which is undesirable.

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 phosphoric acid plasticizer is applied to the copper wire in a manner that gradually reduces the amount of phosphoric acid plasticizer added from the center of the dielectric toward the direction of contact with the insulator. Apply anti-corrosion treatment and before covering the insulator, apply a rust-preventive solution containing 0 to 20% by weight of phosphoric acid plasticizer on the copper wire in contact with the insulator and dry quickly. In this way, the stickiness of the phosphoric acid-based plasticizer film remaining on the copper wire is adjusted and made uniform, and the anti-corrosion film on the copper wire is supplemented at the same time. 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,
Apply anti-rust solutions of the respective compositions shown in Table 1 to the central strand, 6 pre-twisted copper strands, 12 pre-twisted copper strands, and the surface of 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.
0m+*" 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. 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 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 cm long 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: O mark indicates no discoloration, Δ mark indicates slight discoloration, and x mark indicates clear discoloration.

(Note 3) Cut a 30cm long sample from an insulated wire with a hacksaw, and add it to an ammonia aqueous solution with a concentration of 1100pp.
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 thickness of the copper oxide film formed on the surface was determined, and the quality of the corrosion resistance was judged from that value.

The evaluation criteria were as follows: ◯ indicates a coating thickness of less than 0.2 μm, Δ indicates a coating thickness in the range of 0.2 to 0.3 μm, and × indicates a coating thickness exceeding 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: 0 marks are difficult to pull out, Δ marks are slightly pullable, and x marks are large.

As can be seen from the results, in Examples 1 to 7, a rust preventive solution with a phosphoric acid plasticizer amount of 0 to 20% by weight was applied to the ply-twisted copper wire in contact with the insulator before insulation coating, and the copper Since the amount of phosphoric acid plasticizer in the rust preventive solution remaining on the surface of the wire is adjusted to below the critical point of 40% by weight, good results are shown in all tests, but Comparative Example 1 shows good results in the case of contact with an insulator. Because an anti-rust solution is not applied to the ply-stranded copper wire before insulation, the adhesion between the conductor and the insulator is reduced, although it has corrosion resistance.
Conductor pull-out test is unfavorable. Comparative Example 2 has a small amount of benzotriazole added, so a sufficient corrosion-resistant film is not formed on the copper surface, which is unfavorable. Comparative Example 3 is unfavorable. Since the amount of phosphoric acid plasticizer added in the rust preventive solution to be applied is insufficient, the corrosion resistance test is not preferred.In Comparative Example 4, the amount of phosphoric acid plasticizer in the rust preventive solution to be applied exceeds the critical amount. Does not meet conductor pullout test.

〔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. It also sufficiently prevents the problem of discoloration of stranded wire conductors during wire storage, and prevents stress corrosion cracking even if corrosive rainwater enters from the terminals after being installed as outdoor insulated wires. 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, 2 to 70% by weight of a phosphoric acid 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 periphery of stranded wires, the amount of phosphoric acid plasticizer added is gradually decreased from the center of the dielectric toward the direction in which it contacts the insulator, and the amount of phosphoric acid plasticizer added is gradually reduced from the center of the dielectric toward the direction in which it contacts the insulator, and the amount of phosphoric acid plasticizer added is gradually reduced from the center of the dielectric to the direction in which it contacts the insulator. A method for manufacturing an insulated wire, which comprises applying a phosphoric acid plasticizer in an amount of 0 to 20% by weight in a rust preventive solution applied to a copper wire.