JP2871011B2 - Power cable - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power cable having an inner semiconductive layer provided on the outer periphery of a conductor and an outer semiconductive layer provided on an outer periphery of an insulator.

[Prior Art] The general configuration of a power cable is as shown in FIG.
On the inner semiconductive layer 2, an insulator 3 on the outer periphery thereof, and an outer semiconductive layer 4 on the outer periphery of the insulator 3.

The smoothness and adhesion between the semiconductive layer and the insulator interface of such a power cable are important from the viewpoint of improving the reliability of the cable.If an interface irregularity exists, a high electric field is locally formed,
Tree deterioration occurs during corona discharge or water immersion, leading to deterioration in the electrical characteristics of the cable. In view of this problem, studies have been made on both the structural side and the material side of the semiconductive layer, and an extruded semiconductive layer has been developed in place of the semiconductive cloth tape with a lot of fluff. As a material of the extruded semiconductive layer, a material based on a polar ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is mainly used.

[Problems to be Solved by the Invention] Dicumyl peroxide (DCP) or 2,5-dimethyl-2,5-di (t-butyl) is generally used for crosslinking the semiconductive layer based on the resin as described above. Peroxy) hexyne-3
The extrusion molding is usually carried out at about 130 ° C. However,
If extrusion molding is continued for a long time, or if the extrusion temperature is increased to increase the extrusion speed, the addition of this crosslinking agent alone will cause some of the crosslinking agent to decompose during molding, resulting in scorch (burn). Therefore, there is a problem that the breakdown voltage is reduced.

An object of the present invention is to solve the problems of the prior art as described above, and to prevent scorch when melt-molding a semiconductive layer with a resin composition containing a crosslinking agent, and thereby,
It is an object of the present invention to provide a power cable in which a reduction in AC breakdown voltage is prevented.

[Means for Solving the Problems] The power cable of the present invention is a single ring having 0.01 to 10 parts by weight of a dialkyl peroxide and 100 or more parts by weight of an ethylene-based polymer and having at least two or more double bonds in a molecule. An internal semiconductive layer and an external semiconductive layer are formed with a semiconductive resin composition containing 0.01 to 10 parts by weight of the formula hydrocarbon compound and a conductivity imparting agent, and these internal semiconductive layers and external semiconductive layers are It is characterized by being crosslinked.

Further, the power cable of the present invention is an ethylene-based polymer.
Dialkyl peroxide is used in an amount of 0.01 to 1 based on 100 parts by weight.
0 parts by weight, 0.01 to 10 parts by weight of an unsaturated dimer of an aromatic α-methylalkenyl monomer and an inner semiconductive layer and an outer semiconductive layer with a semiconductive resin composition containing a conductivity imparting agent. Is formed, and the inner semiconductive layer and the outer semiconductive layer are cross-linked.

In the present invention, as the ethylene-based polymer, polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and linear very low-density polyethylene, polypropylene, polybutene, and ethylene-vinyl acetate may be used. Examples thereof include a polymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl methacrylate copolymer, and an ethylene-propylene copolymer. These may be used alone or may be blended if necessary.

Representative examples of dialkyl peroxides include dicumyl peroxide (DCP), 1,3-bis- (t-butylperoxy-isopropyl) benzene, 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexyne-3. Dialkyl peroxide is polyolefin 100
It is necessary to add in an amount of 0.01 to 10 parts by weight based on parts by weight. If the amount is less than 0.01 parts by weight, crosslinking cannot be sufficiently performed.

Specific examples of the monocyclic hydrocarbon compound having at least two or more double bonds in the molecule include, for example, 4-methylene-cyclohexene represented by the following formula.

Other compounds include 1,3-cyclohexadiene, 1
-Methyl-1,3-cyclohexadiene, 1,4-dimethyl-
Cyclohexadiene, 1-methyl-4-isopropylidene-cyclohexene, 1-ethyl-4-isopropylidene-cyclohexene, 1-methyl-4-isobutylidene-cyclohexene, 1-ethyl-4-isobutylidene-
Cyclohexene and the like can be mentioned.

The aromatic α-methylalkenyl monomer is represented by the following formula.

Here, R is an aryl group, an alkaryl group, a halogen-substituted aryl group or a halogen-substituted alkaryl group.

The unsaturated dimer of the aromatic α-methylalkenyl monomer in the present invention refers to a dimerized aromatic α-methylalkenyl monomer represented by the above chemical formula in the presence of an acidic catalyst or the like, For example Obtained by dimerizing α-methylstyrene represented by Α-methylstyrene dimer represented by Obtained by dimerizing para-methyl-α-methylstyrene represented by Para-methyl-α-methylstyrene dimer represented by the following formula:

In addition, para-ethyl-α-methylstyrene dimer,
Para-isopropyl-α-methylstyrene dimer, meta-ethyl-α-methylstyrene dimer, meta-methyl-
α-methylstyrene dimer, dimethyl-α-methylstyrene dimer, chloro-α-methylstyrene dimer, chloro-methyl-α-methylstyrene dimer, diethyl-α
-Methylstyrene dimer, methyl-isopropyl-α-
And methylstyrene dimer. These dimers may be used alone or in combination of two or more.

Monocyclic hydrocarbon compound having at least two or more double bonds in the molecule and unsaturated dimer of aromatic α-methylalkenyl monomer is 0.01 to 10 parts by weight based on 100 parts by weight of ethylene polymer. Parts must be added, and 0.01
If the amount is less than 10 parts by weight, the effect of suppressing the occurrence of scorch is insufficient, and if it exceeds 10 parts by weight, the crosslinking reaction is significantly inhibited. It is considered that these additives act to provide hydrogen radicals when the dialkyl peroxide undergoes radical decomposition, and have an effect of delaying scorch during molding.

As the conductivity-imparting agent, conductive carbon black is optimal, and acetylene black and furnace black can be used. It is preferable to add 40 parts by weight of the conductivity-imparting agent to 100 parts by weight of the ethylene-based polymer from the viewpoint of imparting conductivity.

In the present invention, an antioxidant and other additives may be added in addition to the above components.

[Examples] Hereinafter, examples of the present invention will be described together with comparative examples.

A semiconductive composition having the composition shown in each of the examples in Tables 1 and 2 is extrusion-coated on a copper conductor having a cross-sectional area of 60 mm ² to form an inner semiconductive layer. (Density 0.920 g / cm ³ , Melt index 1.0 g / 10 min) 100 parts by weight, Dicumyl peroxide 2.5 parts by weight, Antioxidant
Extrusion coating of a resin composition comprising 0.25 parts by weight, and furthermore, extrusion coating of a semiconductive resin composition having the same composition as the inner semiconductive layer on the outer periphery thereof to form an outer semiconductive layer, followed by heat treatment. A crosslinked polyethylene insulated power cable was made.

The results of evaluating the extrudability, the AC breakdown voltage, and the bloom of the cable produced as described above are shown in the lower columns of Tables 1 and 2.

 In addition, each evaluation was performed based on the following.

Extrusion processability: Judgment was made based on the appearance of the extrusion when the cable was manufactured at an extrusion temperature of 145 ° C., that is, whether or not scorching occurred.

AC breakdown voltage: The dielectric breakdown voltage when the voltage of each sample was increased at a normal temperature at a rate of 20 kV / 10 minutes was measured.

Bloom: The pellet before preparing the cable was kept in a constant temperature bath at 80 ° C. for 10 hours, and then visually evaluated by observing the surface.

As can be seen from Tables 1 and 2, Examples 1 to 10
All have good extrudability and high AC breakdown voltage. On the other hand, Comparative Examples 1, 2, 4, and 5 have poor extrudability and low AC breakdown voltage. Further, Comparative Examples 3 and 6 have good extrusion processability, but due to the large amount of addition, precipitation of additives occurs.

[Effects of the Invention] As described above, according to the power cable of the present invention,
This prevents scorch when extruding a semiconductive layer with a resin composition containing a cross-linking agent, and also allows extruding at a high temperature.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1: conductor, 2: inner semiconductive layer 3: insulator, 4: outer semiconductive layer

Claims (2)

(57) [Claims] (1) 100 parts by weight of an ethylene polymer, 0.01 to 10 parts by weight of a dialkyl peroxide, 0.01 to 10 parts by weight of a monocyclic hydrocarbon compound having at least two or more double bonds in a molecule. A power cable, wherein an inner semiconductive layer and an outer semiconductive layer are formed of a semiconductive resin composition containing a conductivity imparting agent, and the inner semiconductive layer and the outer semiconductive layer are cross-linked. . 2. A dialkyl peroxide is used in an amount of 0.01 to 10 parts by weight, based on 100 parts by weight of an ethylene-based polymer.
An inner semiconductive layer and an outer semiconductive layer are formed by a semiconductive resin composition containing 0.01 to 10 parts by weight of an unsaturated dimer of a methylalkenyl monomer and a conductivity-imparting agent. A power cable, wherein the layer and the outer semiconductive layer are cross-linked.