JPH11353941A - Resin composition for cv cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance peel-off property and reliability in a semiconductive layer of a CV cable for middle and low voltage by including resin and acetylene black having specified iodine adsorption number. SOLUTION: Acetylene black used has 20-50 mg/g, of iodine adsorption number. The acetylene black may be blended as it is with resin, preferably to be blended after granulating in 1-2 mm in the standpoint of uniform dispersion in resin, and in granulation, use of ion exchanged water as a wetting agent is preferable. When the iodine adsorption number of acetylene black is less than the lower limit, the tensile strength of the resin composition is decreased, the resin composition is torn in peeling process, and when exceeding the upper limit value, peeling force is heightened, efficiency in such as cable connection is not enhanced. Blending of 40-100 pts.wt. acetylene black to 100 pts.wt. resin is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having good releasability used for a semiconductive layer material of a CV cable.

[0002]

2. Description of the Related Art CV (Crosslinked polyethylene ins)
The term “ulated polyvinylchloride sheathed cable” refers to a polyvinyl chloride sheathed cable using a cross-linked polyethylene insulator. Since power cables are easy to maintain and manage, they are widely used not only for power distribution but also for ultra-high voltage for power transmission.

A CV cable is composed of a copper core, an inner semiconductive layer, an insulating layer, an outer semiconductive layer, and a coating layer. The inner semiconductive layer and the outer semiconductive layer are made of ethylene mixed with carbon black. -Resin compositions such as vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate are used. In this case, in the case of a high-voltage or ultra-high-voltage CV cable having a working voltage of 33 KV or more, the inner semiconductive layer and the outer semiconductive layer require adhesion and high purity. Acetylene black having an iodine adsorption of 85 to 100 mg / g is used. On the other hand, the operating voltage is 33KV
In CV cables used in less than, a resin having good releasability is used in order to facilitate connection and terminal work, and a resin composition containing furnace black is used as a conductive material. .

[0004]

However, furnace black has a lower purity than acetylene black and has a higher carbon grit content, so that the reliability of the CV cable may be impaired. Acetylene black, on the other hand, is the most reliable material for carbon black for semiconductive layers, but the resin blended with it has lower releasability than the resin blended with furnace black. Workability such as connection of a CV cable for voltage is inferior, and improvement has been awaited.

[0005] The work of peeling the semiconductive layer at the construction site involves making a cut in the semiconductive layer using a special jig and performing peeling along the cut, so that the material is not cut during the work. That is important. Regarding the method for evaluating the peelability, there is an AEIC standard in the United States, according to which a cross-linked polyethylene sheet and a sheet of a semiconductive resin composition are hot-pressed and bonded, and the peeling force of the laminated sheet is 2.7 to It is described as 10.9 kg / 0.5 inch.

The present invention has been made in view of the above, and has as its object a resin composition which is suitable for forming a semiconductive layer of a CV cable for medium / low voltage, has good peelability and high reliability. It is to provide.

[0007]

That is, the present invention relates to a resin composition for a CV cable comprising a resin and carbon black, in which a part, preferably all, of the carbon black is adsorbed in an amount of iodine of 20 to 50 mg / g. Acetylene black.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The adsorption amount of iodine used in the present invention is 20 to 50.
mg / g of acetylene black is, for example,
As described in JP-A-9941, the thermal decomposition temperature of acetylene gas is maintained at 1600 to 1400 ° C. by introducing an inert gas such as H ₂ gas or CO gas or an unsaturated hydrocarbon such as benzene or ethylene. Can be manufactured. In the present invention, the raw powder may be directly mixed with the resin, but from the viewpoint of uniform dispersibility in the resin, it is preferable to mix it after granulating it to about 0.1 to 2 mm. For granulation of acetylene black raw powder, it is desirable to use ion-exchanged water as a wetting agent, the details of which are described in Japanese Patent Publication No. 1-58227.

In the present invention, if the iodine adsorption amount of acetylene black is less than 20 mg / g, the tensile strength of the resin composition is lowered and the resin composition is torn at the time of peeling operation, and if the iodine adsorption amount exceeds 50 mg / g, the peeling force becomes high. Become, CV
Workability such as cable connection is not improved. The iodine adsorption amount of acetylene black can be measured according to JIS K-1474.

The resin used in the present invention is a resin such as an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-butyl acrylate.

The ratio of these resins to acetylene black is based on 100 parts by weight of resin and acetylene black 4
It is preferably from 0 to 100 parts by weight. If the amount of acetylene black is less than 40 parts by weight, sufficient conductivity cannot be imparted, and there is a possibility that the acetylene black may elongate and break in the form of a rubber during the peeling operation. On the other hand, if the amount of acetylene black exceeds 100 parts by weight, it becomes difficult to mold the resin composition, and the releasability also deteriorates.

The mixing and molding of the resin and acetylene black can be performed by an extruder or the like.

[0013]

The present invention will be described more specifically below with reference to examples and comparative examples.

Examples 1 to 4 Comparative Examples 1 to 6 EVA resin (trade name "NUC-326" manufactured by Nippon Yunika)
9 ") 100 parts by weight of various acetylene blacks having different iodine adsorption amounts (parts by weight) shown in Table 1 and 1 part by weight of a crosslinking agent (dicumyl peroxide manufactured by Mitsui Chemicals, Inc.) were mixed. The mixture was kneaded with a 60 ml kneading tester ("Laboplastograph R-60" manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a blade rotation speed of 30 rpm at a temperature of 120 ° C. for 10 minutes. This kneaded material is heated at a temperature of 120 ° C. and a pressure of 100 k with a press machine.
The sheet was pressed at g / cm ² for 10 minutes to form a 1 mm thick semiconductive layer sheet.

To evaluate the releasability of the obtained semiconductive layer sheet, XLPE: cross-linked polyethylene (trade name “HFDJ-4201” manufactured by Nippon Yunika Co., Ltd.) was used at a temperature of 140 ° C.
Pressed at a pressure of 100 kg / cm ² for 10 minutes, thickness 2m
m insulating sheet is formed as a mating material for a peeling test, and these are overlapped with each other at a temperature of 180 ° C. and a pressure of 100 kg / cm.
² was pressed for 10 minutes to produce a 3 mm-thick laminated sheet for a peel test. 0.5 inch width, 10 length
Cut into 0 mm test pieces, peeling speed 500 mm / min
A peel test was performed. The peeling test was performed at 10 measurement points, and the average value of the peeling force and the presence or absence of tearing at the time of peeling were measured. Table 1 shows the results.

[0016]

[Table 1]

When the conductivity of the resin compositions of Examples 1 to 4 was evaluated, the conductivity required for the semiconductive layer of the CV cable was substantially the same as that of the conventional resin composition containing acetylene black. Was.

[0018]

The resin composition for a CV cable according to the present invention comprises:
This material is suitable as a material for forming a semiconductive layer of a CV cable, particularly an outer semiconductive layer, which facilitates the work of connecting and terminating the CV cable, and significantly improves the reliability of the CV cable.

Claims (1)

[Claims] 1. A CV cable resin composition comprising a resin and acetylene black having an iodine adsorption of 20 to 50 mg / g.