JPH02181319A - 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 to be used with a specified composition rate to each copper strand. Even if the thickness of each film of a phosphoric acid-based plastisizer remaining on the copper cable to contact with an insulator is different a little each other and before coated with an insulator, the copper strand to have a contact with the insulator is coated with optionally selected rust preventing solution containing 0-20wt.% of phosphoric acid-based plastisizer and dried rapidly so as to adjust and uniformalize the viscosity of the phosphoric acid- based plastisizer to be left 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.

(Prior art) 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 sometimes discolor. Copper anti-rust solution is applied to copper wire, copper stranded wire, etc. during the manufacturing process.

On the other hand, vinyl chloride insulated wire (OW) is used as an outdoor distribution line.
, polyethylene insulated wire (OE), cross-linked polyethylene insulated wire (OC), etc. are often used, but a black copper oxide film forms on the surface of the VA wire several years after the wire is installed, 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 interaction between 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 W4128 wire and the stress that occurs when overhead wires resist the bending stress that occurs when winding the wire on a drum. It is said to occur due to action.

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, 1) using an insulating layer with anti-rust components added for copper, 2) filling the hard copper m-wire with a watertight compound, and 2) 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 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. 63-45278 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 to coat the surface of a hard copper stranded wire with 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 plasticizer, and the balance being a solvent. After that, in the method of forming an insulating coating layer on the outer periphery of the hard copper stranded wire, before coating the insulator, the amount of phosphoric acid plasticizer added to the copper wire in contact with the insulator is zero.
It is characterized by applying a rust preventive solution of ~20% 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 set at 0.1 to 10% by weight because even if 10% by weight or more is added, a corrosion-resistant film will not be formed any further, so the rust preventive effect is increased. 1 color sum is reached, and an excessive amount causes precipitation, which is not preferable.

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 stranded conductor after application, and the conductor pullout test is not preferred. Conversely, 2% by weight
If it is less than that, it will be difficult to obtain a sufficient rust prevention effect because the protective effect on the corrosion-resistant film formed will be lacking.

Next, in the configuration of the present invention, 0 to 20% by weight of a phosphoric acid plasticizer is added to the copper wire in contact with the insulator before coating the insulator.
For example, in the manufacturing process of 19 hard copper concentric strands, the anti-rust solution is applied to each of the center wire, 6 wood lower-stranded wires, and 12 ply-stranded wires with an amount of phosphoric acid plasticizer. If a rust preventive solution with a large amount of
If an insulator is applied, the adhesion between the insulator and the hard copper stranded wire will decrease, which is not preferable. Therefore, before coating the hard copper stranded wire with the insulator, apply an appropriately selected anti-corrosion solution containing 0 to 20% by weight of phosphoric acid plasticizer, dry quickly, and coat the stranded copper wire with the insulator.
The thickness of the protective film of the phosphoric acid plasticizer remaining on the two ply twisted wires is modified to a thinner state, and further corrosion resistance is added to improve the adhesion between the insulator and the hard W4 twisted wire. do.

In addition, in the manufacturing process of hard copper concentric stranded wire, if the amount of phosphoric acid plasticizer in the rust preventive solution to be applied is close to the lower limit, the amount of phosphoric acid plasticizer should be reduced before coating the insulator. A 20% by weight anti-rust solution is applied onto the ply-stranded strands to complement the anti-corrosion film and provide a protective film with a phosphoric acid plasticizer to ensure excellent corrosion resistance.

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 the present invention, in addition to benzotriazole, pencitriazoyl compounds such as benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, and methylbenzotriazole cyclohexylamine salt are used. Nyl 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 2% to 70% by weight of a phosphoric acid plasticizer and alcohol with 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 is bonded to the copper surface. If a rust-preventive film is well formed by the chelate bond and the alcohol evaporates, the phosphoric acid plasticizer contained will form a protective film on the rust-preventive film, increasing the double rust-preventing effect and improving corrosion resistance. improves.

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, in the manufacturing process of hard copper stranded wire,
A rust-preventing solution with a specific composition to be used is applied to each copper wire to prevent rust. Before coating, an appropriately selected anti-II# solution containing a phosphoric acid plasticizer in an amount of 0 to 20% by weight is applied to the copper wire in contact with the insulator, quickly dried, and then coated on the copper wire. The stickiness of the sulfuric acid plasticizer film left on the copper wire is adjusted and made uniform, and the anti-corrosion film on the copper wire is complemented at the same time. This will prevent 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+++mφ and covering the outer periphery with a polyethylene insulator, the central strand, six first-twisted copper strands, 12 second-twisted copper strands, and Before insulating coating, a rust preventive solution having the composition shown in Table 1 is applied to the surface of the copper wire in contact with the insulator.

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. To apply the coating on the surface of the copper wire that is in contact with the insulator, wrap a weighted felt around the stranded wire, pump a fixed amount of anti-rust solution onto the upper end of the wire using a micro pump, and then pass through a hot air dryer to quickly dry it. .

Subsequently, a polyethylene insulator is extruded and coated on the outer periphery.
011IIIz outdoor polyethylene insulated wire was manufactured. Each of the obtained insulated wires was subjected to a corrosion resistance test (Note 1, Note 2, Note 3) and a conductor pullout test (Note 4) described below. The results are shown in the bottom row of Table 1.

(Note 1) Cut a 10cm+ length sample from the insulated wire with a hacksaw, remove the insulator, and immerse the conductor wire in a sodium sulfide aqueous solution with a concentration of 100pp+m 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 W4 stranded wire, 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 having a concentration of IQOppa+ at room temperature for 30 seconds, 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 30 cm long sample from the insulated wire with a hacksaw, and add it to an ammonia aqueous solution with a concentration of 100 ppa+.
After being immersed in a corrosive environment for 8 weeks, the sample was immersed in a corrosive environment for 8 weeks, followed by a heat cycle of 8 hours at 1,60°C and 16 hours at room temperature and then replaced with a fresh ammonia solution. The average film thickness of copper oxide formed on the conductor was determined, and the quality of corrosion resistance was judged from that value.

The evaluation criteria were as follows: Q 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. A judgment was made as to whether the adhesion was good or bad.

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

As can be seen from the results, in Examples 1 to 6, 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. Since no anti-rust solution is applied to the insulator on the ply-twisted copper wire, although it has corrosion resistance, the adhesion between the conductor and the insulator deteriorates, making the conductor pullout test undesirable. In Comparative Example 2, the amount of benzotriazole added is small, so a sufficient corrosion-resistant film is not formed on the copper surface, which is not desirable. In Comparative Example 3, the amount of benzotriazole added is small, so a sufficient corrosion-resistant film is not formed on the copper surface, which is not preferable. Comparative Example 4 is not suitable for the conductor pullout test because the amount of phosphoric acid plasticizer added in the applied anticorrosion solution exceeds the critical amount.

〔Effect of the invention〕

As explained above, according to the manufacturing method according to the present invention,
Since it is possible to obtain an electric 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 is possible to obtain a wire that has good adhesion to the twisted copper wire in contact with the insulator, and has an excellent corrosion-resistant film and protective film on the stranded wire conductor. In addition to sufficiently preventing the problem of discoloration of stranded wire conductors during storage of wires and wires, stress corrosion cracking can be prevented even if corrosive rainwater enters from the terminals of the wires after they are installed as outdoor insulated wires. The effect is great because there is no need to worry.

Applicant: TAC Electric Wire Co., Ltd.

Claims (1)

[Claims] After applying 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 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, before coating the insulator, a rust preventive solution containing a phosphoric acid plasticizer in an amount of 0 to 20% by weight is applied to the copper wire in contact with the insulator. A method for manufacturing an insulated wire, characterized by: