JPS60124616A - Mixture for semiconductive layer - Google Patents

Abstract

PURPOSE:A mixture for insulated cable semiconductive layers which can be crosslinked at high temperatures without detriment to releasability in the production of cables, obtained by mixing a polyamide resin comprising a dimer acid with an ethylene copolymer, an epoxy resin, and electroconductive carbon. CONSTITUTION:A base polymer is prepared by mixing a polyamide resin obtained by polycondensing a dibasic acid component based on the dimer acid of the formula with a diamine with an ethylene/vinyl acetate copolymer and/or an ethylene/acrylate ester copolymer. This base polymer is mixed with an epoxy resin and electroconductive carbon black (e.g., acetylene black) to obtain the purpose mixture of semiconductive layers. When this mixture is used as a material for external semiconductive layers of crosslinked polyolefin insulated cables, these cables can be subjected to corsslinking treatment at a temperature >=about 300 deg.C without detriment to releasability.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a mixture for a semiconducting layer that is suitably used for a semiconducting layer of a crosslinked polyolefin insulated cable.

Prior Art and Its Disadvantages Conventionally, the material forming the outer semiconducting layer of a crosslinked polyolefin insulated cable mainly uses ethylene vinyl acetate copolymer (gVA) as a base polymer.

A mixture of this and conductive carbon black is used.

In general, the outer semiconducting layer must be in sufficient contact with the inner insulator when the cable is used.
On the other hand, in terminal treatment, it is desired that the terminal can be easily peeled off from the insulator. However, conventional semiconducting layers using ethylene-vinyl acetate copolymers as a base polymer have the drawbacks of excessively high adhesion to insulators made of crosslinked polyolefin resins and difficulty in peeling.

The present inventors have already developed a semiconductor (1) which eliminates such drawbacks, a mixture in which a polyamide resin or a mixture of a polyamide resin and a polyolefin resin (i) is used as a base polymer, and conductive carbon black is mixed therein. This was proposed in Japanese Patent Application No. 58'-2668. However, although this semiconducting mixture has the advantage of being easy to peel off from the insulator, when a cable using this mixture is crosslinked at a high temperature of 300°C or higher, there is a problem that the peelability is reduced. This resulted in the inconvenience that the crosslinking speed of the cable could not be sufficiently increased.

Purpose of the Invention The present invention has been made in view of the above circumstances, and it is possible to ensure peelability between the semiconducting layer and the insulator even if the cable is crosslinked at a high temperature of 300°C or higher, and therefore the crosslinking temperature is set at 300°C. It is an object of the present invention to provide a mixture for a semiconducting layer that can shorten the crosslinking time.

Structure of the Invention The mixture for semiconducting layers of the present invention comprises a base polymer consisting of a polyamide resin made of dimer acid, an ethylene vinyl acetate copolymer and/or an ethylene ethyl acrylate copolymer, an epoxy resin and conductive carbon black. It is made by blending.

The polyamide resin made of dimer acid, which is one component of the base polymer used here, is made of dimer acid (a typical structural formula of which is shown in formula (l)), which is a dimer of unsaturated fatty acids. Single item or this dimer acid plus adipic acid and azelaic acid.

A polycondensate of a mixture of dibasic acids such as cepatic acid and diamines such as hexamethylene diamine, and has an average molecular weight of 1,000 to 100.0 On, preferably 3,000 to 50,000. Milve is preferred, but is not limited to this; other polyamide resins can also be used. Examples of commercially available polyamide resins include Milve
x, Persalon, Persamide, Macromel) (all manufactured by Henkel Japan), etc.

Moreover, as the other component of the base polymer, ethylene vinyl acetate copolymer and ethylene ethyl acrylate copolymer are used. Ethylene vinyl acetate copolymer (E
VA), vinyl acetate (VA) content is 10~
General varieties of 50 wt% are mainly used, and as ethylene ethyl acrylate copolymers (IA), those with an ethyl acrylate (EA) content of 10 to 30 wt% are mainly used, but none of them are particularly limited. It is not something that will be done. EVA and EEA are each added alone to the polyamide resin to form a base polymer, or EVA and EEA are mixed in a predetermined ratio and then added to the polyamide resin to form a base polymer. E
When VA and EEA are added alone to polyamide resin, the mixing ratio is polyamide resin@/EVA t B E
EA weight II ratio is often set to 10/9° or more,
Preferably, the range is 20,780 to 40/60. If this mixing ratio is less than 10/90, it becomes difficult to separate the resulting semiconducting layer from the insulator.Also, when adding a mixture of EVA and EIDA to a polyamide resin to form a base polymer, EVA The mixing ratio of EVA and IA may be any desired mixing ratio.The mixing ratio of the mixture of EVA and EEA and the polyamide resin is the same as the above mixing ratio.

As the epoxy resin added to this base polymer, common bisphenol A-based resins and cycloaliphatic resins are widely used, but are not particularly limited, but are liquid at room temperature and have an epoxy equivalent of 100 to 3001F/eq, A book with a certain level is preferable. The amount of this epoxy resin added to the base polymer is as follows:
If the amount is less than 0.5 parts by weight, it will be difficult to separate the insulator and the semiconducting layer if the crosslinking temperature during cable manufacturing is 300°C or higher. Even if the amount exceeds the weight part, it is no longer possible to increase the effect of increasing the crosslinking temperature, and it is also uneconomical.

Conductive carbon black added to impart conductivity to the above base polymer.

Well-known carbon blacks such as acetylene black and furnace black can be used. What is the mixing amount of the above carbon black with respect to the base polymer?

It is determined in consideration of the conductivity required for semiconducting layers.

Usually 10 to 100 per 10 parts by weight of base polymer
Parts by weight.

Further, a crosslinking agent, a crosslinking aid, an anti-aging agent, etc. can be added to the mixture for a semiconductive layer formed by mixing the base polymer, epoxy resin, and carbon plaque, as required.

As a crosslinking agent, dicumyl peroxide (DCP),
Common peroxide crosslinking agents such as 2,5-dibutyl-2,5-di(t-butylperoxy)hexyne-3 can be suitably used, and examples of crosslinking aids include ) realyl cyanurate, ) Reallylinosocyanuride (1m-)unishin bismaleimide and the like can be used. These crosslinking agents and crosslinking aids.

Both may be used in combination or either may be used alone. In addition, as an anti-aging agent, 4,4'-thiobis(6
-1-butyl-3-methylphenol), etc. can be used.

Then, an outer semiconducting layer can be formed using a mixture having such a composition in the same manner as in the conventional method.

This can be done by applying a normal extrusion coating method to a cable formed with an insulator.

Experimental Example [Experimental Example] Mixtures for semiconducting layers according to the present invention were prepared in Tables 1 to 8 shown in the following table.
Eight types of formulations were prepared. Also.

For comparison, blends for comparison were prepared using three types of formulations 9 to 11 shown in the following table.

An insulating layer was formed by extrusion coating a polyethylene resin containing 2 wt.% dicumyl peroxide (DCP) as a crosslinking agent onto an annealed copper stranded wire having a cross-sectional area of 501 jl.

Next, the above-mentioned various mixtures were similarly extruded and coated to form an outer semiconductive layer, which was then crosslinked at different crosslinking temperatures to produce 11 types of cables.

For these 11 types of cables, the peel force required to peel off the outer semiconductive layer was measured based on the standard of AEICC85-791'L1. The results are also shown in the table.

As shown in the table, the cables whose outer semiconducting layer was formed using the mixture according to the present invention had an outer semiconducting layer of 1 to 1.5 inches and 10.5 inches even when the crosslinking temperature was raised to 380°C. It can be peeled off with a certain amount of peeling force. On the other hand, a prior invention that does not contain epoxy resin (Japanese Patent Application No. 58-2668)
It is difficult to peel off the mixture at a crosslinking temperature of 300°C.

Effects of the InventionAs is clear from the results of the experimental examples described above, the mixture for semiconducting layers of the present invention is effective for semiconducting layers such as the outer semiconducting layer formed on the surface of the insulating layer of a crosslinked polyolefin insulated cable. This mixture is suitable as a material for cables with a semiconducting layer.

Good adhesion between the insulator and the semiconducting layer is maintained during normal use, and the semiconducting layer can be easily peeled off from the insulator during terminal treatment. Furthermore, even if the crosslinking temperature during cable manufacture is raised to 380° C., the easy peelability is maintained, the crosslinking time can be shortened, and the cable manufacturing efficiency can be increased.

Claims (1)

[Claims] A mixture for a semiconductive layer comprising a polyamide resin comprising a dimer acid, a base polymer comprising an ethylene vinyl acetate copolymer and/or an ethylene ethyl acrylate copolymer, an epoxy resin, and conductive carbon black.