JPS6290805A - Power 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 [Field of Industrial Application] The present invention relates to a power cable having a semiconducting layer on either a conductor or an insulator.

[Prior Art] Extruded semiconductive layers are often used for the internal and external semiconductive layers of cross-linked polyethylene cables in order to prevent W-plane irregularities with the insulator.

As the material for this extrusion type semiconductor 7t7@, ethylene-based copolymers, especially ethylene-vinyl acetate copolymers, are preferred due to their ease of extrusion and filling properties with conductive carbon black. ing.

[Problems to be Solved by the Invention] However, the ethylene/vinyl acetate copolymer generates acetic acid under the action of heat and moisture, which tends to discolor and corrode copper.

Therefore, there is a problem in that the copper conductor and the copper tape for shielding the insulator are susceptible to discoloration and corrosion due to the cross-linking process using high-temperature, high-pressure steam during cable manufacturing or when the cable is used in a humid atmosphere.

The present invention deals with discoloration of copper conductors and copper tapes for shielding insulators caused by semiconductive layers mainly composed of ethylene/vinyl acetate copolymer, 1. The object of the present invention is to provide a power cable that can prevent W eclipse.

[Means for Solving the Problems] The power cable of the present invention is a power cable in which a semiconducting layer is formed on a conductor or an insulator, in which the semiconducting layer is formed with an ethylene-vinyl acetate copolymer and a conductive material. carbon black as the L component, and the ethylene/hinyl acetate jtt
It is characterized in that it is formed from a resin composite containing 0.5 to 10 [1 part of synthesis/aluminum fluoride J, calcium] to 1 part of E-combined ++10@l.

The base polymer in the semiconductive composition of the present invention is an ethylene/vinyl acetate copolymer, and in addition, polyethylene, polypropylene, polybutene, ethylene/ethyl acrylate copolymer, ethylene/methyl acrylate copolymer, ethylene/propylene Rubber, ethylene/vinyl acetate copolymer graft-polymerized with an aromatic monomer such as styrene, etc. may be used in combination.

The conductive carbon black is generally acetylene black or furnace black, and the amount added is 20 to 100 parts per 100 ffi of the ethylene/vinyl acetate copolymer.
100 parts by weight is common.

Synthetic aluminum/calcium silicate is CaO/Al
It is a type of calcium-substituted synthetic zeolite having the composition formula 2O3.2 S IO2.4 H7LO, and is used as a material for copper discoloration and corrosion.

The amount of synthetic aluminum/calcium silicate added is 0.5 to 1001 parts of ethylene/vinyl acetate copolymer.
It is necessary to keep it in the range of ~10 parts by weight; if it is less than 0.5 parts by weight, there will be no positive effect on copper discoloration or corrosion, and if it exceeds 10 parts by weight, the extruded appearance of the semiconductive layer will deteriorate.

The reason why discoloration and corrosion of copper can be suppressed by containing synthetic aluminum/calcium silicate is thought to be because synthetic aluminum/calcium silicate adsorbs acetic acid, which causes discoloration and corrosion.

In the present invention, crosslinking agents, antioxidants, lubricants, etc. are appropriately blended.

As a crosslinking agent, dicumyl peroxide, l.

3-bis-(t-butylperoxy-isoprobyl)-
Benzene, 2,5-dimethyl-2,5-di(1-butylperoxy)-hexane, 2,5-dimethyl-2,5
-di(t-butylperoxy)-hexine-3 and the like.

Examples of antioxidants include 4,/l'-thiohis(co(=methyl-6-t-butylphenol), 2,2°4
-Trimethyl-dihydroquinoline polymer, N.

Examples include N'-diphenyl-p-phenylenediamine, 2-mercaptohesoimidazole and its curved salt.

Examples of lubricants include stearic acid, metal salts thereof, and paraffin wax.

[Example 6] The compositions shown in Example 6 in Table 1 were kneaded in a Banbury mixer, and then a crosslinking agent was added to prepare a conductive composition.

The above conductive r is placed on a copper stranded conductor with a conductor area of 150 mtri'
1 composition to form an internal semiconducting layer, followed by low density polyethylene (density 0.9203/cm3,
Melt index 1.0) 1001
Utabe○ Dicumyl peroxide 2.0 parts by weight 0
4. Extrude an insulator composition consisting of 4'-(3-methyl-6-I-butylphenol') 0.2 parts i1[t, and further apply the above semiconducting composition 1 on the outer periphery of the insulating composition. The outer semiconducting layer was formed by extrusion coating a 1111 tl tube.

These extrusions are then heated! ! J! A Shibahashi polyethylene insulated power cable was fabricated by applying a steel tape for shielding the insulator, a vinyl sheath, etc. to the bridge.

Evaluation results for the cables thus produced are shown in the first & column.

The evaluation is 1 Te as follows.

Corrosion of copper conductors and O1 tape for shielding insulation can be prevented by cutting the cable to a specified length, sealing both ends, energizing the cable, and subjecting it to a heat cycle from room temperature to 105°C (conductor temperature). 4 hours 0N-4 hours OF I” 1
After turning the cable 00 times, the cable was disassembled and judged by visual observation. Note that the surface temperature of the outer semiconducting layer was 75°C when the conductor temperature was 105°C.

What is the volume resistivity of external semiconductor after heat cycle? t
Jr! ! The temperature was measured.

In Examples 1 to 3, which are within the scope of the present invention, there was no discoloration or corrosion of the copper conductor or copper tape, and results comparable to those of practical humans were obtained in terms of volume resistivity and extrusion appearance.

In Comparative Example 1, which did not contain synthetic aluminum/calcium silicate, and Comparative Example 2, which contained less than the specified value of the present invention, discoloration and corrosion were observed.

Comparative Example 3, in which the content of synthetic aluminum/calcium silicate was higher than the specified value of the present invention; the extrusion appearance was poor.

[Effects of the Invention] As explained above, the present invention prevents discoloration and corrosion of copper conductors and insulation shielding copper tapes caused by the ethylene-vinyl acetate copolymer used as the main component of the semiconductive layer. This makes it possible to prevent this problem and improve the long-term reliability of power cables.

Claims (1)

[Claims] (1) In a power cable in which a semiconductive layer is formed on a conductor or an insulator, the semiconductive layer is mainly composed of an ethylene/vinyl acetate copolymer and conductive carbon black, A power cable comprising a resin composition containing 0.5 to 10 parts by weight of synthetic aluminum/calcium silicate based on 100 parts by weight of the copolymer.