JPH02260325A - Power cable - Google Patents

Abstract

PURPOSE:To obtain a semiconductive layer having proper peeling property and adhesion to an insulating layer by blending a specified amount of conductive carbon black to ethylene.butene-1 copolymer or a blend polymer of this copolymer with a polyolefin polymer other than this. CONSTITUTION:The outer circumference of a conductor 1 is coated with an inner semiconductive layer 2. The inner semiconductive layer 2 is coated with an insulating layer 3. The insulating layer 3 is further successively coated with an outer semiconductive layer 4, a shielding layer 5 and a sheath 6 to form an electric power cable. The outer semiconductive layer 4 is formed by extruding and coating a resin composite in which 10-100 parts by weight of conductive carbon black is blended to 100 parts by weight of ethylene.butene-1 copolymer alone or a blend polymer of 5wt.% or more of this copolymer with less than 95wt.% of a polyolefin polymer other than this on the insulating layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power cable such as a cross-linked polyethylene insulated cable, and the semiconductive layer thereof has improved peelability.

[Conventional technology]

For power cables such as cross-linked polyethylene insulated cables (CV cables), insulating layers made of cross-linked polyethylene or cross-linked ethylene propylene rubber, etc. It is necessary to make the conductive layer easy to peel off. Furthermore, it is also necessary that interfacial peeling between the insulating layer and the semiconducting layer does not occur when an external bending force is applied to the power cable. Therefore, the semiconducting layer needs to have both appropriate releasability and appropriate adhesion to the insulating layer.

For this reason, conventionally, polar polymers such as polyvinyl chloride, chlorinated polyethylene, and ethylene-vinyl acetate copolymers, fluororesins, silicone resins, etc. are blended with an appropriate amount of polyolefin resins such as polyethylene to form a base polymer, and this is made into a base polymer. The semiconductive layer is made of a resin composition containing carbon black, and is designed to have appropriate peelability and adhesion to an insulating layer made of a polyolefin resin such as crosslinked polyethylene or crosslinked ethylene propylene rubber.

[Problem to be solved by the invention]

However, in the case of a semiconducting layer made of the above-mentioned resin composition, since this resin composition is a blend of a polyolefin resin and a polar polymer that is inherently poor in compatibility with this polyolefin resin, it is difficult to uniformly conduct wires when cross-wired. Therefore, when the semiconducting layer obtained from this resin composition is peeled from the insulating layer, directionality is developed.
There was a problem in that the cable could not be peeled off in any direction, making it difficult to easily process the ends of the power cable.

[Means to solve the problem]

In this invention, the resin composition forming the semiconductive layer is an ethylene-butene-1 copolymer or a blend polymer of this copolymer and another polyolefin polymer.
00 parts by weight, conductive carbon black 10-1
The above problem was solved by using a compound containing 0.00 parts by weight.

The present invention will be explained in detail below.

FIG. 1 shows an example of the power cable of the present invention, and reference numeral 1 in the figure indicates a conductor. The outer periphery of this conductor 1 is coated with an internal semiconducting layer 2 . This internal semiconducting layer 2 is
This is a bond type semiconductive layer, which is different from the one with good releasability in the present invention. Furthermore, this internal semiconducting layer 2 is coated with an insulating layer 3. This insulating layer 3 is composed of a ←:4 resin composition obtained by extruding a polyolefin resin such as cross-linked polyethylene or cross-linked ethylene propylene rubber and then cross-linking it by heating.

Furthermore, on this insulating layer 3, an external semiconducting layer 4 and a shielding layer 5 are formed.
and sheath 6 are sequentially coated to form a power cable.

The outer semiconductive layer 4 is made of conductive carbon based on 100 parts by weight of an ethylene-butene-1 copolymer alone or a blend polymer of 5% by weight or more of this copolymer and 95ffifft% or less of other polyolefin polymers. A resin composition containing 10 to 100 parts by weight of black is applied to the insulating layer 3.
It is formed by extrusion coating on top.

The ethylene/butene-1 copolymer, which is one component of the base polymer used here, consists of ethylene and butene-1 copolymer.
It is a copolymer of 1 and 2 using Ziegler catalyst polymerization technology, has a butene-1 content of 10 mol % or more, and is a polymer with excellent water resistance, chemical resistance, electrical insulation, etc.

In addition, the other component of the base polymer, olefin polymers, includes ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, etc. Examples include α-olefin copolymers and blend polymers of two or more thereof, and among them, ethylene-vinyl acetate copolymers and ethylene-ethyl acrylate copolymers are particularly preferred. The ethylene-vinyl acetate copolymer preferably has a vinyl acetate content of about 10 to 35% by weight and a melt fluoride of 1 to 20. This ethylene-vinyl acetate copolymer improves the processability of the base polymer and facilitates the dispersion of carbon black into the base polymer.

Further, as the ethylene-ethyl acrylate copolymer, one having an ethyl acrylate content of about 10 to 25% by weight is preferable because it imparts appropriate flexibility to the base polymer.

In addition, as a base polymer, the above ethylene butene-1
When using a blend polymer of a copolymer and other polyolefin polymers, the mixing ratio is ethylene/
The proportion of the butene-I copolymer is 5% by weight or more and the polyolefin polymer is 95% by weight or less, preferably the ethylene-butene-1 copolymer is 30% by weight or more and the polyolefin polymer is 70% by weight or less. It is said that If the content of the ethylene-butene-1 copolymer is less than 5% by weight, it will be difficult to separate the outer semiconducting layer 4 from the insulating layer 3, resulting in inconvenience.

Conductive carbon black is added to such a base polymer to impart conductivity. As the conductive carbon and black here, well-known carbon blacks such as acetylene black and furnace black can be used. The amount of conductive carbon black to be mixed with the base polymer is determined in consideration of the conductivity required for the outer semiconductive layer 4, and is 10 parts by weight per 100 parts by weight of the base polymer.
It is determined in the range of ~100 parts by weight.

Further, a crosslinking agent, a crosslinking aid, an anti-aging agent, etc. can be added to the resin composition made of the mixture of the base polymer and carbon black, if necessary. As a crosslinking agent, dicumyl peroxide (DCP), 2.5-
Common peroxide crosslinking agents such as dimethyl-2,5-di(t-butylperoxy)hexyne-3 can be suitably used.

The blending amount of the crosslinking agent is approximately 0.2 to 3 parts by weight per 100 parts by weight of the base polymer. In addition, as the crosslinking aid, triallyl isocyanurate, triallyl cyanurate, tetraallyloxyethane, NIN'-m-phenylene bismaleimide, p, p dibenzoyl lequinone dioxime, p-quinone dioxime, etc. can be used. It can be blended in an amount of about 0.5 to 3 parts by weight per 100 parts by weight of the base polymer. These crosslinking agents and crosslinking aids may be used in combination, or either one may be used alone. When a crosslinking aid is used alone, a portion of the crosslinking agent in the insulator migrates to the semiconducting layer during crosslinking and reacts with the migrated crosslinking agent to cause crosslinking. In addition, as an anti-aging agent, 4゜4'-thiobis(6
-t-butyl-3-methylphenol) etc. can be used,
In addition, zinc stearate, zinc oxide, magnesia, etc. can also be added as necessary.

In order to form the outer semiconductive layer 4 using such a composition, an extrusion coating method can be applied in the same manner as the conventional method. The extrusion temperature during this extrusion coating is 120~
It is said to be around 140°C.

In such a power cable, the outer semiconductive layer 4 is made of a resin composition mainly composed of an ethylene-butene-1 copolymer or a polyolefin polymer other than this copolymer. It has appropriate adhesion and appropriate peelability to the insulating layer 3 made of propylene rubber, etc., and the base polymer itself becomes a uniformly dispersed system, so that it can be peeled off in a specific direction when the semiconducting layer is peeled off. It can be easily peeled off in any direction as needed without causing any inconvenience such as easy peeling.

Hereinafter, the effects of this invention will be clarified by showing examples.

〔Example〕

A resin composition having the formulation shown in Table 1 was prepared as an outer semiconductive layer. On the conductor (500 mm), an internal semiconducting layer (1 mm thick), an insulating layer (cross-linked polyethylene, 11 mm thick)
mn+), an outer semiconducting layer (thickness 0, 5 mff1) was coated by a three-layer interlayer extrusion coating, followed by a shielding layer and a sheath to produce a power cable.

Regarding the obtained power cable, the presence or absence of directionality during peeling of the outer semiconductive layer was investigated. Separately, a sheet piece with a two-layer structure made of this resin composition and crosslinked polyethylene was extruded and its peel force was determined. The results are also shown in Table 1.

As is clear from Table 1 below, in the power cable of the present invention, there is no directionality when peeling the semiconducting layer, and it can be peeled off in any direction, and the peeling force and adhesion to the insulating layer It can be seen that the power is balanced.

〔Effect of the invention〕

As explained above, the power cable of the present invention comprises a ethylene-butene-1 copolymer or a blend polymer of this copolymer and other polyolefin polymers.
00 parts by weight, conductive carbon black 10-1
Since it has a semiconductive layer made of a resin composition containing 0.00 parts by weight, when peeling the semiconductive layer from the insulating layer during terminal processing work etc., it can be peeled off as much as necessary in any direction. Therefore, terminal processing work can be easily performed. Further, this semiconductive layer has appropriate adhesiveness and appropriate releasability to an insulating layer made of crosslinked polyethylene or the like.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of the power cable of the present invention.

Claims (2)

[Claims] (1) From a resin composition containing 10 to 100 parts by weight of conductive carbon black to 100 parts by weight of an ethylene-butene-1 copolymer or a blend of this copolymer and other polyolefin polymers. A power cable with a semi-conducting layer. (2) The power cable according to claim (1), wherein the ethylene-butene-1 copolymer is 5% by weight or more, and the other polyolefin polymers are 95% by weight or less.