JPS6139312A - Semiconductor oriented composition for 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 [Field of Industrial Application] The present invention relates to a semiconductive composition provided on the outer periphery of a conductor and/or the outer periphery of an insulator of a power cable.

[Prior art] The smoothness and adhesion of the interface between the semiconductive layer and the insulator of the cross-linked polyethylene insulated cable are important for the reliability of the cable, and if there is any irregularity at the interface, a localized high electrolyte is formed, leading to corona discharge. Water tree deterioration occurs when the cable is submerged or submerged in water, reducing the electrical characteristics of the cable.

To solve this problem, studies have been completed from the viewpoint of manufacturing methods and materials for semiconductive layers, and an extruded semiconductive layer has been developed to replace semiconductive cloth tape, which has a lot of curls. It was done.

Looking at materials for extruded semiconductors, there are those with base polymers of ethylene-vinyl acetate copolymer and ethylene-ethylene acrylate copolymer, and those with base polymers of ethylene-propylene rubber and h-density polyethylene rubber. There have been conventionally known methods.

In particular, semiconducting compositions based on a mixture of ethylene-propylene rubber and high-density polyethylene can be produced in tandem by arranging an internal semiconducting extruder and an insulating extruder in series. In this case, the internal semiconducting layer is less likely to be damaged or deformed, and since a polymer having a fS structure similar to that of the insulator is used, the interface has good smoothness and adhesion.

[Problems to be Solved by the Invention] A crosslinked polyethylene insulated power cable having such a semiconductive layer has a significantly improved breakdown voltage;
If power is applied for a long period of time under severe deterioration conditions such as water seepage inside the cable, water trees will occur frequently and the breakdown voltage will drop by 1".
There is a problem that

The present invention solves the problems of the prior art described above.
The object of the present invention is to provide a semiconductive composition that can improve the water resistance of power cables.

Means for Solving Problem E] The semiconductive composition of the present invention contains at least 40 parts by weight of the conductivity imparting agent based on 100 parts by weight of the ethylene-acrylic acid ester-unsaturated silane compound terpolymer. It is made by blending.

In the present invention, the ethylene-acrylic acid ester-unsaturated silane compound terpolymer is produced by copolymerizing ethylene, acrylic acid ester, and an unsaturated silane compound in the presence of a radical polymerization initiator, a chain transfer agent, etc. This is what I did.

Here, the unsaturated silane compound is represented by the following formula.

CH2=C(R) Coo (CH2) x Si
RV'(OCH3)5-V (R is (or CH3), R- is CH3 or Cz.

Hs, X is 1-6, preferably 3-5. y is O-3, preferably 0. ) In the present invention, in addition to the above-mentioned radical copolymerization, the ethylene-acrylic acid ester-unsaturated silane compound terpolymer is prepared by adding an unsaturated silane compound to the ethylene-acrylic acid ester copolymer as an f2-dissociating radical generator. The unsaturated silane compound may be graft copolymerized in the presence of the following formula.

CH2=CH5t(OR)3 (R is CH3, C2, Hs.) Examples of acrylic esters include methyl 7-acrylate, ethyl acrylate, and propyl acrylate.

Examples include butyl acrylate, methyl methacrylate, and ethyl methacrylate.

The content of acrylic ester in the ethylene-acrylic ester-unsaturated silane compound terpolymer is 2% by weight or more, preferably 5% by weight or more from the viewpoint of water tree inhibition, and the content of the unsaturated silane compound is 2% by weight or more, preferably 5% by weight or more. is 0.1~1
5% by weight, preferably 0.5-3% by weight. If the content of the unsaturated silane compound is too large, there will be a problem that the polymer will adhere to the die during extrusion.

In the present invention, other polymers such as polyethylene, ethidone-vinyl acetate copolymer may be used as appropriate.

Ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, ethylene-butene copolymer, etc. can be mixed.

Carbon blacks such as channel black, furnace black, and acetylene black are typical examples of conductivity-imparting agents for imparting conductivity to the above-mentioned terpolymer or a mixture of this and other polymers. .

The conductivity imparting agent must be blended in an amount of 40 parts by weight or more; if it is less than this, the desired conductivity cannot be obtained.

Such a semiconductive composition is extrusion coated on the outer periphery of the conductor and/or the outer periphery of the insulator. .

Although such an anticonductive layer can be used in a non-crosslinked state,
Heat resistance can be improved by crosslinking.

The most typical crosslinking method is to add an organic precipitate such as dicumyl peroxide and heat after extrusion, but other methods include irradiation crosslinking by irradiation with ionizing radiation, Water crosslinking, which is brought into contact with water in the presence of a catalyst, can be achieved.

[Example] A semiconductive composition obtained according to the formulation shown on each side of Table 1 was extrusion coated onto a stranded copper conductor having a cross-sectional area of 150# to form an internal semiconductive layer. 1, low density polyethylene (density 190,920, melt index 1.
0) 100mff 1st part, dicumyl pero main side 2.
5 parts by weight of an insulating composition, and 0.25 parts by weight of an antioxidant is extrusion coated, and the same anti-conductive layer as the internal anti-conductive layer (1) 5% by weight of ethyl acrylate m is coated on the outer periphery of the insulating composition. Unsaturated silane compound m1% by weight, melt index 1.5 (2) butyl acrylate f+) 10% by weight
, unsaturated silane compound ff11.5% by weight, melt index 2.5 (3) Vinyl acetate amount 15% by weight, melt index 5 (4) Ethyl acrylate ff1201M%, melt index 3.5 [Effects of the invention] The above As is clear from the description, according to the present invention, a power cable with excellent water tree resistance can be obtained.

Claims (2)

[Claims] (1) A semiconductive composition for power cables, comprising 40 parts by weight or more of a conductivity imparting agent based on 100 parts by weight of an ethylene-acrylic acid ester-unsaturated silane compound terpolymer. . (2) The content of the acrylic ester in the ethylene-acrylic ester-unsaturated silane compound terpolymer is 2% by weight or more, and the content of the silane compound is 0.1% by weight or more.Claim 1 The semiconducting composition for power cables described in 2.