JPH0215508A - Composition for forming semiconductive layer - Google Patents

Abstract

PURPOSE:To make it possible to combine low volume resistivity and high mechanical strength which can meet practical use by making it contain specific components. CONSTITUTION:Additives such as cross linking agent, cross linking assistant, processing material, age resistor, etc., are added at need to insulating resin 100 weight portion, conductive carbon black 20-80 weight portion and charge- transfer typeboron polymer 0.2-4 weight portion which are selected from polyolefine and olefine copolymer. This way, the charge-transfer type boron polymer is used in combination with conductive carbon black as the conductive material which is added and mixed to matrix resin. Hereby, a semiconductive layer which has low resistivity and high mechanical strength can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the use of internal and/or external semiconducting layers of power cables having semiconducting layers on conductors and/or on insulators. RESIN-BASED COMPOSITIONS Suitable for Formation.

[Conventional technology and its issues]

Conventionally, semiconducting layers formed in cross-linked polyethylene insulated cables for high voltage, etc. have been used for the purpose of alleviating the potential gradient between the conductor and the insulating layer and preventing partial discharge to the outside. The volume resistivity of the semiconducting layer itself is required to be kept as low as possible. Further, this semiconductive layer is required to have a sufficiently large mechanical strength to withstand tension or elongation in the length direction of the cable, for example, when the cable is laid.

Conventionally, resin base materials used for such semiconductive layers include, for example, ethylene-vinyl acetate copolymer, ethylene-dityl acrylate copolymer, ethylene-α-olefin-diene terpolymer, ultra-low density Olefin polymers such as polyethylene are used, and a suitable amount of conductive carbon black is blended therein.

On the other hand, in order to obtain good conductivity in such semiconductive materials, it is necessary to increase the amount of conductive carbon black added to the base resin. but.

The larger the amount of conductive carbon black added to the base resin, the harder and more brittle the semiconductive layer becomes and the lower its stretchability becomes.

There are problems such as a decrease in mechanical strength and a tendency to crack. Therefore, as far as the amount of conductive carbon black is concerned, lowering the volume resistivity and improving mechanical strength of the semiconductive layer are contradictory properties.

It has been practically difficult to obtain a semiconducting layer having both properties that are sufficiently satisfactory for practical use.

Therefore, an object of the present invention is to provide a coating material composition capable of forming a semiconductive layer having both a practically satisfactory low volume resistivity and high mechanical strength. Another object of the present invention is to provide a molding material composition with good extrusion coating properties.

[Means to solve the problem]

The present inventors have conducted a number of prototype studies on methods for achieving the above object, focusing in particular on conductive materials.
We have developed a material composition that can form a semiconducting layer that is highly desirable in practice.

That is, the present invention comprises: (a) 100 parts by weight of an insulating resin selected from polyolefins and olefin copolymers; (b) 20 to 80 parts by weight of conductive carbon black; and (c) 0.2 to 80 parts by weight of charge-transfer type boron polymer. 4 parts by weight and (d) optionally additives such as a crosslinking agent, a crosslinking aid, a processing aid, and an anti-aging agent.

The composition for forming a semiconductive layer of the present invention has a technical feature in that a charge transfer type boron polymer is used in combination with conductive carbon black as a conductive material added to the matrix resin.

The charge transfer type boron polymer of component (c) used in combination with the conductive carbon black of component (b) is, for example,
A B-N complex polymer having the following skeleton structure:
The present invention is based on the discovery that when such boron polymers are used as electrically conductive materials in combination with electrically conductive carbon black, the above objects can be effectively achieved.

Examples of such boron polymers include Hiboron CTP-200 and Hiboron CTN-200, which are sold and provided by Boron International Co., Ltd.
131 is typical.

Further, as the conductive carbon black, for example, commonly known acetylene carbon black, furnace type conductive carbon, etc. are suitable.

Preferred insulating resins as component (a) used in the composition of the present invention are olefin homopolymers and olefin-containing copolymers, such as polyethylene, ethylene-vinyl acetate copolymers, Ethylene-ethyl acrylate copolymer, ethylene-α-olefin copolymer, ethylene-α-olefin-polyene copolymer,
Examples include ultra-low density polyethylene. These resins are usually used alone, but
Two or more types can also be used in combination.

Conductive carbon black of the above component (b) and component (c)
It is important to use the boron polymers in combination in an appropriate range ratio;
The component (b) is 20 to 80 parts by weight and the component (c) is 0.2 to 4 parts by weight, respectively.

When the amount of carbon black as component (b) is less than 20 parts by weight.

The conductivity of the semiconductive layer is insufficient, and if the amount exceeds 80 parts by weight, not only the mechanical strength of the formed semiconductive layer decreases, but also the extrusion processability deteriorates, which is not preferable. If the amount of the boron polymer used as component (c) is less than 0.2 parts by weight, sufficient conductivity will not be obtained, and the effect of the combination with component (b) will be insufficient, so that the object of the present invention will not be achieved.
Even if the amount exceeds 4 parts by weight, it is industrially disadvantageous because a commensurate effect of improving conductivity cannot be obtained.

In addition, component (c) for carbon black of component (b)
) is used in an amount of 1, usually 0.5 to 10%, preferably 1
Although the amount is approximately 5%, the amount to be used is appropriately selected depending on the conductivity required for the semiconductive layer and the amount of carbon black used.

Component (b) and component (c) may be added separately to the resin of component (a), or may be mixed in advance and then added and kneaded.

The composition of the present invention may optionally contain various additives such as a resin crosslinking agent, a crosslinking aid, and a processing aid.

Anti-aging agents, modifying resins, etc. can be added.

Examples of crosslinking agents include dicumyl peroxide, 2,
Examples include peroxides such as 5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and examples of crosslinking aids include triallylisocyanurate.

Cyanurates such as triallyl cyanurate can be mentioned. In addition, examples of anti-aging agents include zinc stearate, zinc oxide, magnesia, and the like. Examples of reinforcing and modifying resins include halogenated polymers such as chlorinated polyethylene and chloroprene. can.

[action, effect]

The composition for forming a semiconducting layer of the present invention can provide a semiconducting layer for a high voltage cable that has both low volume resistivity and high mechanical strength that are practically satisfactory as a semiconducting layer,
In addition, it has good extrusion coating processability and has excellent practical value.

〔Example〕

Next, the composition of the present invention will be explained in more detail using specific examples.

Example 1 Ethylene-vinyl acetate copolymer (EVA) (Mitsui DuPont Polychemical Company I2: Evaflex 27o) 1
00 parts by weight, 40 parts by weight of carbon black (Nidenka Black manufactured by Denki Kagaku Kogyo Co., Ltd.), and 1 part by weight of charge transfer type boron polymer (Hiboron CTP-200).

Dicumyl peroxide (manufactured by Nihon Yushi Co., Ltd.: Percumil D)
1.5 parts by weight, 0.5 parts by weight of an anti-aging agent (Nikrac 300 manufactured by Iriuchi Shinko Kagaku Kogyo Co., Ltd.) and 0.5 parts by weight of zinc stearate (St-zinc) were mixed together using a mixing roll and mixed uniformly. A composition was prepared.

Next, the obtained sheet-like composition was heated using a hot press.
Pressing was carried out at a temperature of 160° C. for 40 minutes to create a 1 m+++ sheet.

Volume resistivity and J of the obtained sheet at 90°C
The elongation rate (
The tensile elongation at break) was measured. Their results are 6×10 3 Ω·C and 400%, respectively, which are highly desirable as semiconducting layers.

Examples 2 to 6 and Comparative Examples 1 to 4 Hiboron CTP-200 or Hiboron CTN-131 (both charge transfer type manufactured by Boron International) were used as various ethylene resins and boron polymers, and the same Denka polymer as in Example 1 was used. Black, as well as Park Mill D and Tsukrak 300. Various compositions were made using zinc stearate, and measurement samples were prepared in the same manner as in Example 1.
The volume resistivity and elongation rate were each investigated. The components of each composition, their blending ratios, and each measured value are summarized in Table 1 below together with the results of Example 1.

The substances with abbreviations in Table 1 are as follows.

EEA: Ethylene-ethyl acrylate copolymer (manufactured by Nippon Petrochemical Co., Ltd.: Nippon Rexron C-9052) V
LDPE: Ultra-low density polyethylene (manufactured by Nippon Petrochemical Co., Ltd.:
Soft Rexron C-9052) In addition, when the compositions of Example 3 and Comparative Examples 2 and 3 were extruded and coated on conductive wires, and the extruded state and appearance of the extruded wires were examined, it was found that both Example 3 and Comparative Example 2 Comparative Example 3 was also good, but Comparative Example 3 was bad. On the other hand, when the composition of Example 3 was formed into the inner semiconducting layer or the outer semiconducting layer, the respective volume resistivities were 4×10'Ω·mark and 2×103Ω·mm, whereas Comparative Example 2 The compositions are lXl0'Ω・■ and 8×10′Ω・
It was a mark.

This fact and Table 1 show that the compositions of the present invention can provide semiconducting layers with low resistivity and high mechanical strength.

Claims (2)

[Claims] 1. (a) 100 parts by weight of an insulating resin selected from polyolefins and olefin copolymers (b) 20 to 80 parts by weight of conductive carbon black (c) 0.2 to 4 parts by weight of charge-transfer type boron polymer (d) A composition for forming a semiconductive layer of a power cable, which contains additives such as a crosslinking agent, a crosslinking aid, a processing aid, and an anti-aging agent, if necessary. 2. A composition according to claim 1, wherein the boron polymer of component (c) is a B-N boron complex.