JPS61183817A - Manufacture of crosslinked polyolefin insulated 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 The present invention relates to a method for manufacturing a crosslinked polyolefin insulation power cable, and in particular, to eliminate gaps between an internal semiconductive layer and an insulating layer in a high voltage silane crosslinked polyolefin cable to improve adhesion. The present invention relates to a method for manufacturing a silane-crosslinked polyolefin insulated power cable whose dielectric breakdown strength is improved by improving the silane-crosslinked polyolefin insulated power cable.

Conventionally, cross-linked polyolefin insulated back-type piezoelectric cables mainly made of cross-linked polyethylene and cross-linked EPR have been
Volume resistivity is 100 by blending conductive carbon black
It is manufactured by sequentially extruding and coating an inner semiconducting layer and, if necessary, an insulator layer, with an outer semiconducting layer using a semiconducting resin composition adjusted to have a resistance of ~10'Ω. ing. In this case, there are various crosslinking methods, but the silane crosslinking method has the advantage of requiring simple equipment for crosslinking. However, as a method for obtaining a silane-crosslinked polyolefin resin molded article, for example, the method disclosed in Japanese Patent Publication No. 1711/1983 can be seen, but this silane crosslinking method uses conventional organic peroxide coating after extrusion coating. Unlike physical crosslinking, continuous crosslinking tubes for heat crosslinking under pressure are not required. Therefore,
Silane crosslinked polyolefin insulated power cables are increasingly being manufactured and used.

However, in silane crosslinked polyolefin insulated cables manufactured without using continuous crosslinked pipes,
There was no problem with low-voltage cables, but high-voltage cables are provided with an inner semiconducting layer and an outer semiconducting layer if necessary, but this semiconducting layer is formed using an extruded cross-linked semiconducting layer. When formed using a semiconductive composition, no pressure is applied during the crosslinking treatment, resulting in poor adhesion at the interface between the semiconducting layer and the insulating layer, and voids exist, especially at those locations. If it is between 1 and 2, it causes a significant decrease in dielectric breakdown strength.

The purpose of the present invention was to eliminate the drawbacks observed in the conventional methods, and to eliminate the gap between the internal semiconducting layer and the insulating layer in a high voltage silane cross-linked polyolefin insulated cable. The object of the present invention is to provide a method for producing a crosslinked polyolefin insulating capeple which has improved dielectric breakdown strength by satisfactorily improving its adhesion.

That is, the method for manufacturing a silane-crosslinked polyolefin insulated power cable according to the present invention includes, on a conductor 1, an extruded crosslinked internal semiconductive layer 8, a silane crosslinked polyolefin insulator layer 2,
In manufacturing a high voltage crosslinked polyolefin insulated power cable by sequentially forming the outer semiconductive layer 4 as necessary,
The internal semiconductive layer 8 is made of linear low density polyethylene 95-40
5 to 60% by weight of ethylene copolymer, conductive carbon black, and the general formula RR'
S IYg C In the formula, R is a monovalent olefinically unsaturated hydrocarbon group or a hydroperoxy group, Y is a hydrolyzable organic group, and R' is a monovalent hydrocarbon group containing no aliphatic unsaturation. , a group Y or hydrogen) with a volume resistivity of 10' to 106 (λ
- It is characterized in that it is formed by extrusion molding of a semiconductive composition of the sieve (see Figure 1).

Here, the linear low density polyethylene is a copolymer of ethylene and an olefin having 4 to 8 carbon atoms, and methods for producing long chain branches include a gas phase method and a liquid phase method.

In the present invention, this linear low-density polyethylene was selected because of its high adhesion strength to the printed polyolefin insulating layer. (c) It has very good crack resistance, so no cracks will appear between extrusion molding and crosslinking.

It depends on that.

The reason why the linear low-density polyethylene selected as the base material for forming the semiconductive layer was limited to 95 to 40% by weight is that if it exceeds 95% by weight, the flexibility will deteriorate and the smoothness of the semiconductive layer will deteriorate. This is because if it is less than 40% by weight, the adhesion will be poor and voids will be likely to occur.

On the other hand, in the present invention, the ethylene copolymer is ethylene-
Considering vinyl acetate copolymer, ethylene-acrylic acid copolymer, etc., the reason for limiting the proportion in the base material is 60% by weight.
This is because if it exceeds 5% by weight, the adhesion with the insulating layer will deteriorate, and if it is less than 5% by weight, the flexibility will deteriorate.

Further, the conductive carbon black used in the present invention is not particularly limited, and examples thereof include conductive furnace black such as Palkan XO-72 manufactured by Cabot, and Denka black manufactured by Denki Kagaku Kogyo Co., Ltd. Examples include acetylene black and Ketj an black manufactured by AKZO, and the amount thereof is usually in the range of 5 to 70 parts by weight per 100 parts by weight of the pace polymer. In addition, as the silane compound, vinyltrimethoxysilane, vinyl) IJ ethoxysilane, etc. are usually used, and the blending amount is 0 to 100 parts by weight of the pace polymer.
．． 5 to 5 parts by weight are used.

In addition, the external semiconducting J# formed as necessary in the present invention
is formed by winding a semiconductive tape or by extrusion molding a semiconductive resin composition, or in particular, by using a semiconductive resin composition in the same extrusion mold used for forming the internal semiconductive layer. This is preferable because the effect of further improving the electrical characteristics can be obtained.

Examples of the present invention will be described below in comparison with comparative examples.

Table 1 shown below summarizes the compositions (parts by weight) of the semiconductive compositions and cable characteristics of the corresponding cables for each Example and Comparative Example.

That is, a silane crosslinked semiconductive composition was prepared by blending 2.0 parts by weight of vinyltrimethoxysilane, 0.2 parts by weight of dicumyl oxide, and 0.1 parts by weight of a silanol catalyst into each of the semiconductive compositions shown in Table 1. 250n8 conductor 1 (
(See Figure 1) and on the outer periphery of the 8.5-thick silane cross-linked polyethylene insulating layer 2 to form an inner semi-conductive layer 3 and an outer semi-conductive layer 4, respectively, to a thickness of 1.0 mm. 6
A KV crosslinked polyethylene cable was manufactured. The cable characteristics of each cable thus obtained were evaluated. The obtained results are also listed in Table 1. As is clear from the table, all of the products of Examples 1 to 8 have better adhesion (between the internal semiconducting layer and the insulating layer) and smoothness (of the cable surface) than Comparative Examples 1 to 3. is good, the AG breakdown voltage is also high, and the cable characteristics are good.

Table 1: Methane Example 4 and Comparative Example 4 The same silane crosslinked semiconductive composition used in Example 8 was deposited on a 250 tm2 conductor for 1. On thick, 8 on top
．． An insulating layer made of silane cross-linked polyethylene with a thickness of 5fi, and a removable semiconductive composition on top of the insulating layer 1.
A 6KV silane-crosslinked polyethylene insulated cable was manufactured by continuously extruding 8 layers to a thickness of 0fi.For comparison, the same silane-crosslinked semiconductive composition used in Comparative Example 2 was coated on a 250-cm conductor. 1.0fi thick and 8.
An insulating layer made of silane cross-linked polyethylene was applied to a thickness of 5fi, and on top of that, eight layers of the same peelable semiconductive composition used in Example 4 were continuously extruded to a thickness of 1.0fi. A 6 KV silane cross-linked polyethylene insulated cable was manufactured.

The characteristics of the thus obtained cable were measured in the same manner as in Example 1. The results obtained are shown in Table-2.

Table 2 As stated above, as an effect of the present invention, by using the semiconductive composition as specified in the present invention, by taking advantage of the equipment advantages of the silane crosslinking method, silane crosslinking high pressure with excellent characteristics can be achieved. It became possible to manufacture cables.

That is, the gap between the inner and outer semiconducting layers and the insulating layer in the high-voltage silane crosslinked polyolefin isolation cable was eliminated to improve adhesion and dielectric breakdown strength.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a cross-linked polyolefin insulation region capeple according to an embodiment of the present invention. °1...Conductor

Claims (1)

[Claims] 1. Manufacturing a high voltage crosslinked polyolefin insulated power cable by sequentially forming an extruded crosslinked internal semiconductive layer, a silane crosslinked polyolefin insulating layer, and an external semiconductive layer as necessary on a conductor. In doing so, the internal semiconductive layer of the extrusion mold is made of 95 to 40% by weight of linear low density polyethylene and 5 to 6% by weight of ethylene copolymer.
Conductive carbon black and general formula RR'SiY_2 (wherein R is a monovalent olefinic unsaturated hydrocarbon group or a hydroperoxy group, and Y is a hydrolyzable organic group, R' is a monovalent hydrocarbon group containing no aliphatic unsaturation, a group Y or hydrogen), and the volume resistivity is 1.
1. A method for producing a crosslinked polyolefin insulated power cable, characterized in that the cable is formed by extrusion molding of a semiconductive composition having a thickness of 0^0 to 10^6 Ω-cm. 2. An extruded internal semiconductive layer and an optional external semiconductive layer are conductive to a base polymer consisting of 95 to 40% by weight of linear low-density polyethylene and 5 to 60% by weight of ethylene copolymer. carbon black and general formula RR'SiY_
2 (wherein R is a monovalent olefinic unsaturated hydrocarbon group or a hydroperoxy group, Y is a hydrolyzable organic group,
R' is a monovalent hydrocarbon group containing no aliphatic unsaturation, group Y
or hydrogen), and formed by extrusion molding of a semiconductive composition having a volume resistivity of 10^0 to 10^6 Ω-cm. 2. A method for producing a crosslinked polyolefin insulated power cable according to item 1.