JPH02181318A - Manufacture of insulated electric cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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. , fI stranded wires, etc. are coated with a commercially available anti-rust solution.

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 copper wire several years after the wiring is completed, 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, 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 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. Sho 63-7869 that a rust preventive solution in which specific amounts of benzotriazole or/and a benzotriazole derivative and a phthalic acid plasticizer were dissolved in a solvent was applied to stranded hard copper 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-rust solution to the stranded wire, a strong corrosion-resistant film is formed on the surface of the copper wire or hard copper stranded wire, and even if corrosive rainwater penetrates inside the hard copper stranded wire, the copper color will remain for a long time. It is an object of the present invention to provide a method for manufacturing an insulated wire and a power cable that maintains the same properties and has good adhesion between an insulator and a hard copper stranded wire.

[Means for solving problems]

As a result of intensive studies to solve the above problem, the present inventors found that the amount of phthalic 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. %, and completed the present invention.

The structure of the present invention is to apply a rust preventive solution consisting of 0.1 to 10% by weight of benzotriazole or/and benzotriazole derivative, 2 to 70% by weight of phthalic acid plasticizer, and the balance being a solvent to the surface of the hard copper stranded wire. After that, in the method of forming an insulating coating layer on the outer periphery of the hard copper stranded wire, a phthalic acid plasticizer is added to the copper wire in contact with the insulator in an amount of 0 to 20% by weight before coating the insulator. It is characterized by applying an anti-rust solution.

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 phthalic acid plasticizer used is 2 to 70% by weight is that if it is more than 70% by weight, stickiness remains on the stranded conductor after application and the conductor pullout test is not preferable. 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, applying a rust preventive solution containing a phthalic acid plasticizer in an amount of 0 to 20% by weight to the copper wire in contact with the insulator before coating the insulator is, for example, 19 In the manufacturing process of this hard copper concentric t= wire, if a rust preventive solution containing a large amount of phthalic acid plasticizer is applied to the center line, 6 first-stranded wires, and 12 first-stranded wires, the upper twist 12
Since a thick protective film of phthalic acid plasticizer remains on the surface of this wire, applying an insulator will reduce the adhesion between the V@green body and the hard copper stranded wire, which is undesirable. Before coating the wire with insulation, add 0 to 20% of the phthalate plasticizer.
Appropriately select and apply an anti-corrosion solution of % by weight and dry quickly to thin the protective film of the phthalic acid plasticizer remaining on the 12 twisted strands in contact with the insulator. Furthermore, corrosion resistance is imparted to improve the adhesion between the insulator and the hard copper stranded wire.

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

The phthalic acid plasticizers used in the present invention include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, di-n-octyl phthalate, higher alcohol phthalate, diisooctyl phthalate,
Diisobutyl phthalate, diethyl phthalate, diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, dinonyl phthalate, dinormal alkyl phthalate, benzyl phthalate, dimethoxyethyl phthalate, dimethylcyclohexyl phthalate, alkyl benzyl phthalate, methyl phthalyl glycolate, etc. 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 phthalic acid plasticizer, and to adjust the viscosity of the phthalic acid 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 benzodiazole such as benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, and methylbenzotriazole cyclohexylamine salt. Triazole 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 with the copper wire in contact with the A-edge, 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 to 10
When a rust preventive solution consisting of 2 to 70 wt% phthalate plasticizer and alcohol with the balance being a solvent is applied to the surface of a hard copper strand, in the presence of the alcohol, the copper surface will be coated with the rust preventive component. A rust-preventing film is well formed due to chelate bonding,
When the alcohol volatilizes, the contained phthalic acid plasticizer forms a protective film on the rust-preventing film, thereby enhancing the dual rust-preventing effect and improving corrosion resistance.

However, the amount of phthalic acid plasticizer added in the anti-corrosion solution is large, and the thicker the film of phthalic 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, hard copper I! ! In the manufacturing process of the 8 glands, a rust-preventing solution of a specific composition is applied to each copper wire to prevent rust, and the film thickness of the phthalate plasticizer remaining on the copper wire in contact with the insulator is slightly reduced. Even if there is, before coating the insulator, the amount of phthalic acid plasticizer added is
Appropriately select a rust preventive solution of % by weight and apply it on the copper wire in contact with the insulator and quickly dry it to adjust and homogenize the viscosity of the phthalic acid plasticizer film remaining on the copper wire, In addition, since the anti-rust coating on the copper wire is supplemented at the same time, 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+nmφ and covering the outer periphery with a polyethylene insulator, the central strand, 6 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.
011Ill12 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 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 10c+n 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.

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 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 formed on the surface was determined, and the corrosion resistance was judged from that value.

The evaluation criteria were as follows: ◯ mark indicates a film thickness of less than 0.2 μm, Δ mark indicates a film thickness in the range of 0.2 to 0.3 μm, and X mark indicates a film thickness exceeding 0.3 μm.

(Note 4) Cut a 3m long sample from an insulated wire with a hacksaw.
Separate the insulator at one end by 0.3 m and fix the other end. Observe how the insulator is pulled out when a load of 1 ton (pulling load) is applied to the insulator at one end. The adhesion to the body was determined.

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 phthalate plasticizer amount of 0 to 20% by weight was applied to the ply-stranded copper wire in contact with the insulator before insulation coating, and the copper The amount of phthalic acid plasticizer in the rust preventive solution remaining on the wire surface is 40
Since the weight percentage is adjusted to below the critical point, good results are shown in all tests, but in Comparative Example 1, the anti-rust solution was not applied to the insulator on the ply-stranded copper wire in contact with the insulator. 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 undesirable. In Comparative Example 3, the corrosion resistance test was not desirable because the amount of phthalic acid plasticizer added in the rust preventive solution applied to the center line, first-twisted and top-twisted copper wire was insufficient, and in Comparative Example 4, the rust preventive solution applied was Since the amount of phthalic acid plasticizer in the solution exceeds the critical amount, it does not meet the 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. I have no worries,

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 phthalic 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 an epoxy 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: