JPS63294614A - Crosslinked-polyethylene-insulated aerial cable - Google Patents

Abstract

PURPOSE:To prevent forming a recessed part on a stranded wire copper conductor by providing the first layer containing triazole copper rust preventives and the second layer of a thin heat resistant organic high polymer film containing a filler and making the second layer to be in the conductor side. CONSTITUTION:A layer of a separator tape 2 composed of the first layer 21 containing triazole copper rust preventives and the second layer 22 of a heat resistant organic high polymer film of 30-200 mum thickness containing a filler is provided on the immediate upper part of a stranded wire copper conductor 1 with the layer 22 made to be in the conductor 1 side, furthermore, a crosslinked-polyethylene insulated layer 3 is provided on the tape 2 layer. Consequently, even if a non-crosslinked-polyethylene component substance layer is heated at a high temperature in order to crosslink and thereby a triazole compound in the layer 21 vaporizes heavily, a sudden reaction between a triazole compound vapor and copper on the conductor 1 surface is prevented as the film of the layer 22 acts to hinder translation of a large quantity of the vapor toward the conductor 1 side. This prevents forming a recessed part on the conductor 1.

Description

[Detailed description of the invention] Cliff m old” 1! The present invention relates to a novel cross-linked polyethylene insulated overhead cable in which a separator tape containing a copper rust preventive agent is applied directly above a copper conductor.

In order to prevent stress corrosion of copper conductors in polyethylene insulated overhead cables, a copper rust preventive agent is applied directly above the W4 conductor, but this method does not apply to copper conductors. Since the amount of copper rust preventive applied directly above is small, the corrosion protection effect lasts for an extremely short period of time. For this purpose, instead of the above proposal, there is also a proposal to mix a rust preventive agent into the polyethylene insulation layer. The copper rust preventive agent mixed in the polyethylene insulation layer gradually migrates to the copper conductor side and has an anticorrosion effect, and also has the advantage that a large amount of copper rust preventive agent can be blended into the polyethylene insulation layer. Therefore, this IIC is generally expected to be of similar practical utility.

By the way, when the insulating layer is made of crosslinked polyethylene, it is necessary to heat and crosslink the uncrosslinked polyethylene composition coated directly over the copper conductor under pressure when manufacturing the cable.
At this time, there is a problem that the uncrosslinked polyethylene composition flows into the gap between the copper conductors due to pressurization. In order to solve this problem, a separator tape made of polyester or the like is wrapped in advance directly above the copper conductor to prevent the above-mentioned inflow. However, there is another problem in that the presence of this separator tape blocks the copper rust inhibitor that has migrated from the crosslinked polyethylene insulating layer, making it impossible to achieve sufficient corrosion protection.

``Problems to be Solved'' Considering the above circumstances, the present inventors first investigated using a separator tape containing a copper rust preventive agent, such as a nonwoven fabric tape containing a copper rust preventive agent.The tape structure was devised. By doing so, the tape can contain a large amount of copper rust preventive agent, and by applying it directly above the copper conductor, the various problems of the conventional methods described above have been solved.However, as a separator tape, copper has no rust preventive effect. It has been found that when using a triazole compound containing an excellent triazole compound, the following new problem arises.

That is, when manufacturing a crosslinked polyethylene insulated overhead cable using a separator tape, the separator tape is applied directly above the copper conductor, an uncrosslinked polyethylene composition containing an organic peroxide crosslinking agent is extruded on top of the separator tape, and then a high The uncrosslinked polyethylene composition layer is crosslinked by heating under pressure at a high temperature of about 180 to 220°C. By heating at this high temperature of around 180-220℃,
The triazole compound contained in the separator tape violently vaporizes and reacts with the copper on the conductor surface, resulting in an excessive amount of
Moreover, the triazole-copper compound is generally formed non-uniformly, resulting in the formation of recesses that can cause cracks in the stranded copper conductor due to stress corrosion.

Triazole compounds originally act as an effective copper rust preventive when they react gradually with copper and uniformly generate a very small amount of triazole-copper compounds on the copper surface to the extent that they do not cause embrittlement of the copper conductor. However, once the triazole-copper compound is generated in excess and non-uniformly, the triazole compound and copper react to a high degree even at low temperatures, and the formation of recesses on the copper conductor progresses.

- Therefore, the present invention aims to provide a novel crosslinked polyethylene insulated overhead cable in which triazole-copper compounds are not excessively produced even if the uncrosslinked polyethylene composition layer is crosslinked by heating at high temperature. be.

As a means for solving the above-mentioned problems in order to improve the overall performance, the present invention provides a heat-resistant organic polymer with a thickness of 30 to 200 μm containing a first layer containing a triazole copper rust inhibitor and a filler. a layer of separator tape consisting of a second layer of molecular film;
An object of the present invention is to provide a crosslinked polyethylene insulated overhead cable having a layer directly above the stranded copper conductor on the side of the stranded copper conductor, and further having a crosslinked polyethylene insulation layer thereon.

In the present invention, a separator tape having a structure consisting of a first layer containing a triazole copper rust inhibitor and a second layer of a heat-resistant organic polymer film is used as a separator tape, and this separator tape Since the layer is applied on the stranded copper conductor side directly above the stranded W4 conductor, during the production of the cable of the present invention, even if the uncrosslinked polyethylene composition layer is heated at high temperature in order to crosslink it, Even if the triazole compound in the first layer vaporizes violently, the heat-resistant organic polymer film in the second layer acts to prevent a large amount of the triazole compound vapor from migrating to the stranded copper conductor side. Prevents rapid reaction with copper on the surface of the wire copper conductor. As a result, the formation of recesses on the stranded copper conductor is prevented.

On the other hand, a two-layer heat-resistant organic polymer film has the following two conditions.

il+ should be thin with a thickness of 30 to 100 μm,
(2) It is composed of a heat-resistant organic polymer composition containing a filler.

That is, the heat-resistant organic polymer film is thin,
Moreover, since it contains a filler, it is microscopically porous. This porosity does not prevent the gradual vaporization of the triazole copper rust inhibitor at low temperatures after cable manufacture or during cable operation, and as a result, the surface of the stranded copper conductor remains unchanged for a long period of time. The migrating triazole copper rust inhibitor provides effective rust prevention.

Large cliff ± Figure 1 is a sectional view of an embodiment of the present invention, Figures 2 and 3 are
All figures are cross-sectional views of examples of separator tapes used in the present invention.

In FIG. 1, 1 is a stranded copper conductor, 2 is a separator tape vertically attached on the LFI copper wire rod conductor 1, and 3 is a crosslinked polyethylene insulation layer applied on the separator tape 2 layer. In FIGS. 2 and 3, 2 is a separator tape, 21 is a layer 171 containing a triazole copper rust inhibitor, and 22 is a second layer made of a thin heat-resistant organic polymer film. In FIG. 1, the separator tape 2 is attached vertically with its second layer 22 facing the stranded copper conductor l.

In the present invention, examples of triazole compounds used include benzotriazole, tolyltriazole, methyltriazole, and especially benzotriazole. The content of the triazole compound in the first layer is preferably at least 5 g per ml of the first layer, particularly preferably at least 10 g/rr+, most preferably at least 20 g/n
? It is preferable that it is contained.

In the present invention, the heat-resistant organic polymer film of the second layer 22 is composed of a heat-resistant organic polymer composition containing a filler. Examples of the heat-resistant organic polymer include those that exhibit good shape stability even at high temperatures during crosslinking, such as polyester, nylon, and poly-4-methylpentene-1. As fillers, various inorganic fillers and organic fillers may be used, regardless of their chemical species, as long as they are insoluble in the heat-resistant organic polymer and act to make the film microscopically porous. can be used. Examples include talc, clay, calcium carbonate, mica powder, zinc white, alumina, and lead oxide. These fillers preferably have an average particle diameter of 20 μm or less, particularly 10 μm or less, and are used in an amount of 1 to 200 parts by weight, particularly 5 to 150 parts by weight, per 100 parts of the heat-resistant organic polymer. It is preferable.

The heat-resistant organic polymer film of the second layer 22 composed of the above-mentioned composition preferably has a thickness of 30 to 200μI, and if it is less than 30μI, it will have uniform pores due to the inclusion of fillers. It is difficult to obtain a film that maintains its properties, and if the layer is thicker than 200 μm, even if a filler-containing composition is used, the airtightness of the film will be too high, making it difficult to obtain a film at low temperatures after cable production or during cable operation. It also acts to prevent the gradual vaporization of triazole copper rust inhibitors.
The rust prevention effect of the triazole copper rust inhibitor cannot be obtained. Therefore, the thickness of the second layer 22 is preferably 40 to 150
IJs, particularly preferably 50 to 80 μs.

In the separator tape shown in Fig. 2, the first layer is made of rubber or plastic in which a triazole compound is uniformly kneaded, and in the separator tape shown in Fig. It consists of two layers: a fiber layer 211 mixed with the fiber layer 211 and a reinforcing layer 212 for mechanically reinforcing the fiber layer 211. As the base material of the fiber layer 211, woven or nonwoven fabrics of organic polymers such as nylon and polyester, and inorganic fibers such as glass and ceramics are used. As the reinforcing layer 212,
An organic polymer film such as nylon or polyester is preferred.

A separator tape is placed vertically on top of a flammable copper conductor with a cross-sectional area of 150 m, which is made by twisting 19 copper wires with an outer diameter of 3.2 mm, and 2 weights of dicumyl peroxide is placed on top of it. % of the uncrosslinked polyethylene composition was extruded, and then the polyethylene composition layer was continuously crosslinked with steam at 200°C to produce a crosslinked polyethylene insulated overhead cable having a crosslinked polyethylene insulation layer with a thickness of 2.5 mm. .20
The residence time (heating time) of the polyethylene composition layer in the crosslinking cylinder during continuous steam crosslinking at 0°C was 7 minutes. The structure and application method of the separator tape are as follows. .

Separator tape structure and application method: thickness 0.0
55 m long, 40 g/m" in basis weight, and 120 g/m" in benzotriazole content, with a thickness of 0.5 mm on one side.
It has a structure in which a 025 mm polyester film reinforcing layer is attached, and a polyester nonwoven fabric layer is attached vertically on the stranded copper conductor side.

Example 1 Polyester 10
A thin polyester film with a thickness of 50 μm manufactured using a composition uniformly mixed with 120 parts by weight of talc per 0 parts by weight was attached, and the thin polyester film layer was 12! ! A cross-linked polyethylene insulated overhead cable was manufactured using the same method and conditions as in Comparative Example 1, except that the copper wire was attached vertically as the conductor side.

Example 2 Polyester 10
A thin polyester film with a thickness of 30 μm manufactured using a composition uniformly mixed with 20 parts by weight of heavy calcium carbonate per 0 parts by weight was attached vertically with the thin polyester film layer as the stranded copper conductor side. A crosslinked polyethylene insulated overhead cable was manufactured using the same method and conditions as in Comparative Example 1, except for the following points.

Example 3 A composition was prepared by uniformly mixing 150 parts by weight of zinc white per 100 parts by weight of nylon 6.6 on the remaining side of a polyester nonwoven fabric having the same structure as the separator tape used in Comparative Example 1. A thin nylon 6.6 film with a thickness of 75 μm is attached to the thin nylon 6.6 film.
A crosslinked polyethylene insulated overhead cable was manufactured using the same method and conditions as in Comparative Example 1, except that 6 film layers were vertically attached as the twisted vAw4 conductor side.

For each cable of Comparative Example 1 and Examples 1 to 3, the amount of benzotriazole-copper compound generated on the surface of the stranded copper conductor and the recesses formed on the copper wire immediately after production and after being left at 30 ° C. for 100 days. The depth was measured and the results shown below were obtained.

Amount of benzotriazole-copper compound generated on the surface of the stranded copper conductor (mg/1 m cable) Immediately after the production of the two cables, Comparative Example 1, Example 1, Example 2, and Example 3 were 5.3ζ4 and 4.3ζ, respectively. It was 4.8.4.5. In addition, after being left at 30°C for 100 days, Comparative Example 1 and Example 1
, Example 2 and Example 3 are 520.4 and 6.4, respectively.
．． It was 9.4.6.

Depth of recess formed on copper wire (μm): Immediately after cable production, Comparative Example 1, Example 1, Example 2, Example 3
are 1.0 or less, and 1. 0 or less, 1. It was 0 or less and 1.0 or less. Moreover, after being left at 30°C for 100 days, Comparative Example 1, Example 1. Example 2 and Example 3 are as follows:
2.2.1.0 or less, 1. respectively. 0 or less, 1. 0
It was below.

Since the separator tape of the present invention itself contains a large amount of copper rust preventive agent, by vertically or horizontally wrapping the separator tape directly above the copper conductor, the copper conductor can be protected from corrosion for a long period of time. . Further, the tape has a structure consisting of a first layer containing a triazole copper rust inhibitor and a second layer of a thin heat-resistant organic polymer film, and this second layer is applied as the stranded copper conductor side. Therefore, during the production of the cable of the present invention, even if the uncrosslinked polyethylene composition layer is heated at high temperature in order to crosslink, and therefore the triazole compound in the first layer is strongly vaporized, the triazole compound by the second layer is Temporarily prevents the reaction between the triazole copper rust inhibitor and copper due to its migration inhibiting effect. As a result, the formation of recesses on the stranded copper conductor is prevented. Therefore, the cable of the present invention has the advantage that it can be easily manufactured using conventional cable manufacturing methods.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 and FIG.
All figures are cross-sectional views of examples of separator tapes used in the present invention. In FIG. 1, 1 is a stranded copper conductor, 2 is a separator tape vertically placed directly above the stranded copper conductor 1, and 3 is a crosslinked polyethylene insulating layer applied on the separator tape 2 layer. In FIGS. 2 and 3, 2 is a separator tape, 21 is a first layer containing a triazole copper rust inhibitor, and 22 is a second layer consisting of a thin heat-resistant organic polymer film containing a filler. be.

Claims (1)

[Claims] 1. A separator tape layer consisting of a first layer containing a triazole copper rust inhibitor and a second layer of a heat-resistant organic polymer film containing a filler and having a thickness of 30 to 200 μm. having a second layer as the stranded copper conductor side directly above the stranded copper conductor;
A crosslinked polyethylene insulated overhead cable further comprising a crosslinked polyethylene insulation layer thereon. 2. The separator tape has a first layer made of a fiber cloth containing a triazole copper rust inhibitor and reinforced with an organic polymer film, and a thick layer containing a filler on one side of the first layer.
The crosslinked polyethylene insulated overhead cable according to claim 1, which has a structure in which a second layer of a heat-resistant organic polymer film of 0 to 100 μm is attached.