JPH0259564B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrical cable having an outer semiconducting layer around the outer periphery of an insulator made of crosslinked polyolefin. Conventionally, the material for the extruded outer semiconductive layer of cross-linked polyolefin insulated cables has mainly been a mixture of ethylene-vinyl acetate copolymer (EVA) as a base polymer and conductive carbon black mixed therein. ing. Generally, the outer semiconducting layer needs to be in close contact with the insulator formed on the inner layer when the cable is used, while it is desirable that it can be easily peeled off from the insulator during terminal treatment. . However, conventional semiconducting layers using EVA as a base polymer have the disadvantage that their adhesion to insulators is too strong and it is difficult to peel them off. In view of the above circumstances, the present invention provides an electric cable having a semiconductive layer that adheres well to a crosslinked polyolefin insulator made of crosslinked polyethylene resin, ethylene-propylene rubber, etc., and is easily peeled from the insulator. It was done for that purpose. In order to achieve this objective, the present inventors have conducted intensive research and found that by using a polyamide resin or a mixture of a polyamide resin and a polyolefin resin as a base polymer, a mixture with good releasability from crosslinked polyolefin can be obtained. The present inventors have discovered that it can be obtained, and have arrived at the present invention. That is, the present invention provides an electric cable having an insulator made of crosslinked polyolefin and an outer semiconductive layer provided around the outer periphery of the insulator. It is composed of a semiconductive mixture in which 10 to 100 parts by weight of conductive carbon black is mixed with 100 parts by weight of this base polymer, and the peeling force with the insulator is 0.5.
~1.5Kg/0.5 inch, thereby solving the above problem. The present invention will be explained in detail below. FIG. 1 shows an example of the electric cable of the present invention. This electric cable includes an insulator 2 made of cross-linked polyolefin provided on the outer periphery of a conductor 1, an outer semiconductive layer 3 made of a semiconductive mixture provided on the outer periphery of this insulator 2, and an outer semiconductive layer 3 made of a semiconductive mixture provided on the outer periphery of this insulator 2. A sheath 4 is provided at the top. The crosslinked polyolefin forming the insulator 2 is typically crosslinked polyethylene, but is not limited thereto, and crosslinked ethylene-propylene copolymers may also be used. The semiconductive mixture used for the external semiconductive layer 3 uses a polyamide resin or a mixture of a polyamide resin and a polyolefin resin as a base polymer, and 10 to 100 parts of conductive carbon black is added to 100 parts by weight of this base polymer. It is made by mixing parts by weight. This polyamide resin may be a single product of dimer acid (the typical structural formula is shown in formula (1)), which is a dimer of unsaturated fatty acids, or a combination of adipic acid, azelaic acid, cepatic acid, etc. with this dimer acid. A polycondensate of a mixture of dibasic acids and diamines such as hexamethylene diamine, with an average molecular weight of 1,000 to 100,000, more preferably 3,000 to 50,000.
is preferred, but not limited to this, other polyamide resins can also be used. As an example of the commercially available polyamide resin mentioned above,
Examples include Milvex, Persalon, Persamide, and Macromelt (all manufactured by Henkel Japan). In addition, polyolefin resins include polyethylene (PE), ethylene-propylene rubber (EPM,
EPDM), EVA, ethylene-ethyl acrylate copolymer (EEA), etc. can be used. The base polymer of the semiconductive mixture is formed by the above-mentioned polyamide resin alone or by a mixture of the polyamide resin and the polyolefin resin. When a mixture is used as the base polymer, it is desirable that the mixing ratio of polyamide resin/polyolefin resin is 10/90 or more by weight.
If the mixing ratio is less than 10/90, it will be difficult to separate the obtained semiconductive mixture from the insulator. The conductive carbon black added to impart conductivity to the above base polymer is as follows:
Well-known carbon blacks such as acetylene black and furnace black can be used. The mixing amount of the above carbon black to the base polymer is:
It is determined in consideration of the conductivity required for the outer semiconductive layer 3, and is usually based on 100 parts by weight of the base polymer.
10 to 100 parts by weight. Further, a crosslinking agent, a crosslinking aid, an anti-aging agent, etc. can be added to the semiconductive mixture formed by mixing the base polymer and carbon black, if necessary. As a crosslinking agent, dicumyl peroxide (DCP), 2,5-dibutyl-2,5-di(t-
Common peroxide crosslinking agents such as (butylperoxy)hexyne-3 can be suitably used, and triallyl cyanurate, triallyl isocyanurate, m-phenylene bismaleimide, etc. can be used as crosslinking aids. These crosslinking agents and crosslinking aids are
Both may be used in combination or either may be used alone. Further, as an anti-aging agent, 4,4'-thiobis(6-t-butyl-3-methylphenol) and the like can be used. Therefore, the semiconductive mixture comprising the above-mentioned components is suitable for use as a material for the outer semiconductive layer formed on the surface of the insulator layer of the crosslinked polyolefin insulated cable. The outer semiconducting layer can be formed using the above-mentioned mixture by applying a conventional extrusion coating method to the electrical cable on which the insulator 2 has been formed, in the same manner as in conventional methods. The resulting electrical cable has a peeling force between the outer semiconducting layer 3 and the insulator 2 in the range of 0.5 to 1.5 kg/0.5 inch, and the adhesion between the insulator 2 and the outer semiconducting layer 3 during normal use. If the outer semiconducting layer 3 is well-maintained and is treated with an insulator 2,
It can be easily peeled off. Therefore, the electrical characteristics during use are maintained well, and the workability during terminal processing is excellent. Next, the present invention will be explained in more detail with reference to Examples. [Example] Semiconductive mixtures according to the present invention were prepared with five types of formulations Nos. 1 to 5 shown in the table below. In addition, for comparison, mixtures for comparison were prepared using two types of formulations Nos. 6 and 7 shown in the table below. PE containing DCP2wt% in annealed copper stranded wire with cross section area ^50mm2
extrusion coating to form an insulating layer, then extrusion coating each of the above blends to form an outer semiconducting layer;
Seven types of cables were produced. The crosslinking treatment was carried out in 6 kg/cm ² of saturated steam. For the above seven types of cables, the force required to peel off the outer semiconductive layer was measured based on the AEIC CS5-79 H.1 standard. The results are also shown in the table.

[Table] As shown in the table, the electric cables according to the present invention using the semiconductive mixtures of Examples No. 1 to No. 5 were
These external semiconductive layers can be peeled off with a force of about 0.5 to 1.5 kg/0.5 inch, and the external semiconductive layers can be peeled off more easily than those of Comparative Examples No. 6 and 7, which correspond to conventional ones. It was confirmed that As is clear from the above description, the electric cable according to the present invention uses a polyamide resin or a mixture of a polyamide resin and a polyolefin resin as a base polymer as a material for the outer semiconductive layer, and conducts electricity based on 100 parts by weight of this base polymer. By using a semiconductive mixture containing 10 to 100 parts by weight of carbon black and setting the peeling force between the outer semiconducting layer and the insulator to 0.5 to 1.5 kg/0.5 inch, the outer semiconducting layer becomes an insulator. This has the effect that an electric cable can be easily peeled off from the base, and an electric cable with excellent workability in terminal processing can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the electric cable of the present invention. 2...Insulator, 3...Outer semiconducting layer.

Claims (1)

[Scope of Claims] 1. An electric cable having an insulator made of crosslinked polyolefin and an outer semiconductive layer provided around the outer periphery of the insulator, wherein the outer semiconductive layer is made of a polyamide resin or a mixture of a polyamide resin and a polyolefin resin. is the base polymer, and this base polymer 100
Conductive carbon black 10-100 parts by weight
The peeling force between this outer semiconductive layer and the above insulator is 0.5.
Electrical cable characterized by ~1.5Kg/0.5 inch.