JPS60189111A - Electrically insulated cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION This invention relates to improvements in the outer semiconducting layer of solid insulated electrical cables, particularly crosslinked polyethylene insulated electrical cables.

(Background of the Invention) The outer semiconducting layer of an electrically insulated cable is a cable*@
Rt= ,) Yozetsu, Lsu □Kre<Mizwai 5.6 CI=
This is necessary for the electrical performance of the cable, and in terms of workability, it is desired that the insulating layer be easily peeled off during cable connection work.

Conventionally, the semiconductive layer of such cross-linked polyethylene insulated electric cables has mainly been made of ethylene/vinyl acetate copolymer (hereinafter abbreviated as EVA resin) or ethylene/ethyl acrylate copolymer (hereinafter abbreviated as EEA resin). Although a full-length carbon black composition is used,
Since these compositions have strong adhesion to the insulating layer, sufficiently good workability cannot be obtained.

(Disclosure of the Invention) The present invention has been made in view of the above points. That is, the inventors have prepared a copolymer of 50 to 95 parts by weight of an EEA resin having a copolymerized amount of 30 parts or more of ethyl acrylate, a copolymer of an α-olefin having 4 or more carbon atoms, and propylene, and the α-
A composition prepared by adding conductive carbon black to a thermoplastic resin mixed with 50 to 5 parts by weight of a polymer having an olefin copolymerization amount of 10 to 50 parts by weight is extruded onto an insulating layer and coated to form an external semiconductor. It was discovered that by using the outer semiconducting layer as a layer, both good adhesion between the outer semiconducting layer and the insulating layer and easy peelability of the outer semiconducting layer during cable connection work can be achieved. Based on this knowledge, the electrical It was revealed that it is possible to provide an electrically insulated cable with good performance and workability.

Of course, in the present invention, the semiconductive composition is
If necessary, compounding agents such as antioxidants and lubricants may be added, and crosslinking may be performed by adding peroxide and heating or electron beam irradiation. It's okay.

Hereinafter, the present invention will be explained in detail based on experimental examples. .

On a mild steel strand with a cross-sectional area of 60 mm, an internal semiconductive layer (semiconductive composition used was NUC'V9 manufactured by Nippon Unicar Co., Ltd.) was applied.
5.61), insulating layer (polyethylene used: Nippon Unicar Co., Ltd., HI'DJ 1201) fr: sequentially extruded and coated, and on top of that, acylene carbon 7Ofi was added to the resin shown in Table 1. A composition in which 2 parts by weight of dicumyl peroxide was completely added and mixed was extruded and coated, and crosslinked by heating with an infrared heater to form an internal semiconductive layer of 0.8 mm.
Thickness, insulating layer 3.2 mm thickness and outer semiconducting layer 1; O'm
A cable core with a thickness of m was obtained.

Approximately 1.3. After making a cut with a width of mm to reach the insulator, it was pulled at a speed of 500 mm/min and the peeling force was measured.

Separately, a copper tape and a nonwoven fabric restraining tape were sequentially wrapped around these cable cores, and then the corona level was measured at a voltage of 17 kV using each cable with a length of 80 m. Note that the minimum sensitivity of the measuring instrument used was 2pc.

The results of these experiments are all shown in Table 1.

As shown in Table 1, the results of Example 1, Example 2, and Comparative Example 2 show that the electrically insulated cable of the present invention has been used conventionally]! Compared to an electrically insulating cape IC that has an external semiconductive layer using a composition in which conductive carbon black is added to EVA resin or [31UA 101 resin, the external semiconductive layer and insulating layer necessary for electrical performance are Without compromising adhesion,
It can be seen that b) the easy peeling properties of the external semiconducting layer required in cable connection work can be obtained.

At this time, the EEA resin used as part of the base resin is
It is necessary that the amount of ethyl acrylate copolymerized is over 300 parts by weight. That is, Example 1 and Comparative Example 5
As can be seen, the amount of ethyl acrylate copolymerized is 300
This is because if less than 1 part by weight of the ID BA resin is used, good release characteristics cannot be obtained.

In addition, the propylene copolymer used as a part of the base resin has a copolymerization ratio of propylene and α-olefin having 4 or more carbon atoms, which is 10 to 500 to 50% by weight as the copolymerization amount of α-olefin having 4 or more carbon atoms. It is necessary that there is a department. That is, as can be seen from Example 1, Comparative Example 6, and Ratio Example 7, the amount of copolymerization of α-olefin having 4 or more carbon atoms is 1O0
If the amount is less than parts by weight, EEA resin, propylene copolymer,
When mixing conductive carbon black, blocks occur <
<, a good mixed product cannot be obtained, and α- with carbon number of 4 or more
If the amount of copolymerized olefin exceeds 50% by weight, the strength of the outer semiconducting layer itself decreases, and a portion of the broken outer semiconducting layer remains on the surface of the insulating layer, making it impossible to obtain good peeling characteristics.

Furthermore, the mixing ratio of the EEA resin and the propylene copolymer needs to be in the range of 95=5 to 50:50 by weight. That is, as is clear from Example 1, Example 2, Comparative Example 3, and Comparative Example 4, when the mixing ratio of EEA resin is 955 parts by weight, the effect of improving the release force property is small.

Furthermore, if the copolymerization ratio of the PEA resin is less than 50% by weight, the adhesion between the external semiconductive layer and the insulating layer will be poor, resulting in a decrease in the electrical performance of the cable.

As a result of the above, the present invention has an external semiconducting layer having good adhesion and peeling properties with the insulating layer, that is, good electrical properties and excellent workability when connecting cables. It is possible to provide an electrically insulated cable having the following.

Appetizer Rokuya Bone Major Continuation Amendment Written on June 20, 1980 Kazuo Wakasugi, Commissioner of the Patent Office 1. Indication of the case 1982 Patent Application No. 42683 2. Name of the invention Electrically insulated cable 3. Person making the amendment Relationship to the incident Patent applicant location 6-15 Kitahama, Higashi-ku, Osaka Name (213
) President Tetsu Kawakami, Sumitomo Electric Industries, Ltd., Department 4, Agent, Tsuyoshi, 6, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka City, 6, application subject to amendment and correction, - Specification and power of attorney Hagi 7. Contents of the amendment (Imperial) First, submit the application and specification written in detail by type stamp as attached.

■Submit a copy of the proxy with the delegate's seal clearly affixed as shown in the attached sheet.

Claims (1)

[Claims] (1) An electrically insulated cable having an outer semiconductive layer formed by extruding and coating an insulating layer with a semiconductive composition made by adding conductive carbon black to a thermoplastic resin, wherein the thermoplastic resin contains ethylene acrylate. m 3' 0 Ethylene/ethyl acrylate copolymer with overlapping part 5o
95 parts by weight of B, and 50 to 5 parts of a copolymer of α-olefin and propylene having 4 or more carbon atoms, with the α-olefin copolymerized amount ranging from 10 to 50 parts by weight. Electrically insulated cables with special features.