JPS63318007A - Wire and cable - Google Patents

Abstract

PURPOSE:To provide an electric wire/cable with excellent radiation resistance by forming a semi-electroconductive layer from a semi-electroconductive component containing 20 parts by weight or more of electroconductive carbon black with respect to 100 parts by weight of aromatic polyether-ketone. CONSTITUTION:A semi-electroconductive layer is formed from a semi- electroconductive component containing 20 parts by weight or more of electroconductive carbon black with respect to 100 parts by weight of aromatic polyether-ketone. The aromatic polyether-ketone has many aromatic rings in its molecular structure and is excellent in radiation resistance. As electroconductive carbon black to give electroconductivity can be named a one which is used normally as electroconductivity giving agent, wherein target degree of electroconductivity can be obtained first when its 20 parts by weight is added to 100 parts by weight of aromatic polyether-ketone. Thus an electric wire/cable with semi-electroconductive layer is accomplished which has high resistance against radiations.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an electric wire/wire having a semiconductive layer with excellent radiation resistance.
It's about cables.

[Prior Art] In high-voltage electric wires and cables, a semiconducting layer is formed on the outer periphery of either or both of the conductor and the insulator in order to prevent deterioration of the insulator due to corona discharge. Adhesion and smoothness of such semiconducting layers at the insulator interface are important from the viewpoint of reliability of electric wires and cables, and if there is an irregularity at the interface, a high electric field is locally formed, causing corona discharge or water intrusion during flooding. tree deterioration occurs, leading to a decline in the electrical properties of the cable. For this reason, extruded semiconductive layers have been developed in place of semiconductive cloth tapes, which tend to have a lot of fuzz, and a typical example is one based on ethylene-propylene rubber.

[Problems to be solved by the invention] In recent years, electric wires and cables have come to be used in radiation environments such as nuclear power, space, and radiation irradiation facilities.
For example, high-voltage instrumentation cables used around nuclear fusion reactors are now required to have radiation resistance of 10 MGy level. Conventional semiconducting layers based on ethylene-propylene rubber have a radiation resistance of only a few MGy, making them unsuitable for use in harsh radiation environments.

The present invention has been made based on the above, and an object of the present invention is to provide an electric wire/cable having a semiconductive layer with excellent radiation resistance.

[Means for Solving the Problems] The electric wire/cable of the present invention has a semiconductive layer formed of a semiconductive composition containing 20 parts by weight or more of conductive carbon black based on 100 parts by weight of aromatic polyetherketone. It is characterized by the fact that it has been formed.

A typical structural formula of the aromatic polyetherketone that is a component of the composition forming the semiconductive layer is represented by the following. This polymer is a thermoplastic resin that can be extruded and has excellent radiation resistance due to its molecular structure 11=+ (which contains a large number of aromatic rings).

Examples of the conductive carbon black that imparts conductivity to the aromatic polyether ketone include those commonly used as conductivity imparting agents, such as furnace black, acetylene black, and Ketjen black. The required conductivity cannot be obtained unless 20 parts by weight or more of the conductive carbon black is mixed with 100 parts by weight of the aromatic polyether ketone.

In order to mix conductive carbon black with aromatic polyetherketone, it is preferable to use a twin-screw kneader because the processing temperature of aromatic polyetherketone is close to 400°C.

Further, an antioxidant, a lubricant, and the like may be added to the semiconductive composition composed of aromatic polyetherketone and conductive carbon black, if necessary.

The insulator in the electric wire/cable of the present invention is not particularly limited, but it is preferable to use a thermoplastic resin with excellent radiation resistance. Examples include aromatic polyetherketones used as base polymers for sexual compositions.

[Examples of the invention] Example 1 Aromatic polyetherketone (trade name: VICTREXPE)
4. EK, manufactured by ICI) at a ratio of 50 parts by weight of acetylene black to 100 parts by weight. The mixture was introduced into a twin-screw kneader set at OO'C and sufficiently kneaded to prepare a pellet-like semiconductive composition.

Next, using a 28 mm extruder set at 400°C, the above semiconductive composition was extruded to a thickness of 15 mm onto the outer periphery of the nickel-plated conductor with a cross-sectional area of 1.25 mrn2 to form an internal semiconductive layer. 4 and then continued to set the temperature to 400°C.
An insulator was formed by extruding aromatic polyetherketone (trade name: VICTREX PEEK, manufactured by ICI) to a thickness of 0.7 mm using a 0 mm extruder, and then a 28 mm extruder was heated to 400°C. A cable was manufactured by extruding and coating the above semiconductive composition on the outer periphery of the insulator to a thickness of 0.15 mm using an extruder to form an external semiconductive layer.

Example 2 Aromatic polyetherketone (trade name: VICTREXPE)
EK, manufactured by ICI) 100 parts by weight and 20 parts by weight of Ketjenblack were introduced into a twin-screw kneader set at 400°C and sufficiently kneaded to prepare a pellet-like semiconductive composition.

A cable was manufactured in the same manner as in Example 1 using this semiconductive composition.

Example 3 Polyetherimide (trade name Ultem) 0 as an insulator
A cable was manufactured in the same manner as in Example 1, except that the insulator was formed by extrusion coating 00 (manufactured by EPL) at 3'700C.

Comparative Example 1 Using a 4.0 mm extruder set at 400°C, aromatic polyetherketone (trade name: VICTREX PE
E.K.

(manufactured by TCI) to a thickness of 0.7 mm to form an insulator, and a cable was manufactured.

Comparative Example 2 100 parts by weight of low density polyethylene (density 0.920 g/cm2, melt index 3.0) and 60 parts by weight of acetylene black were introduced into a twin-screw kneader set at 120°C and thoroughly kneaded. A pellet-shaped semiconductive composition was prepared.

Next, using a 28 mm extruder set at 150°C, the above semiconductive composition was extruded to a thickness of 0.15 mm onto the outer periphery of a nickel-plated conductor with a cross-sectional area of 25 mm2 to form an internal semiconductive layer. 4.0, which was then set at 400℃.
Using an extruder, aromatic polyetherketone (trade name: VICTREX PEEK, manufactured by ICI) was heated to a thickness of 0.
．． Extrude at 7 mm to form an insulator, and then extrude at 1
Using a 28 mm extruder set at 50° C., the above semiconductive composition was extruded and coated on the outer periphery of the insulator to a thickness of 0.15 mm to form an external semiconductive layer to produce a cable.

Comparative Example 3 Aromatic polyether ken (trade name: VICTREXP)
A ratio of 15 parts by weight of acetylene black to 100 parts by weight (EEK, manufactured by ICI) was introduced into a twin-screw kneader set at 400°C, and sufficiently kneaded to prepare a pellet-like semiconductive composition.

A cable was manufactured in the same manner as in Example 1 using this semiconductive composition.

The results of evaluating the volume resistivity and corona characteristics of the semiconducting layer for the cables of Examples and Comparative Examples are shown in the first table.
Shown in the table. The volume resistivity of the semiconductive layer is measured at room temperature and is 5
It is practical if it is less than ×103Ω-CITI. The corona characteristics were evaluated at the initial stage and after γ-ray irradiation, and the corona starting voltage was 6.9 kV/l0PC (PC: picocoulomb).
The above was judged as good. Note that γ-rays are 1σGy/
[at a dose rate of h] to a dose of OMGy.

Table 1 Examples 1 to 3 within the scope of the present invention show good results in all properties. Comparative Example 1 is an example of a cable that does not have a semiconductive layer and has poor corona characteristics. Comparative Example 2 is an example in which low-density polyethylene was used as the base polymer of the semiconductive layer, and the corona properties after γ-ray irradiation were significantly reduced. Comparative Example 3 is an example in which the amount of conductive carbon black mixed is less than the specified value of the present invention, and the corona properties are poor due to poor conductivity.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to realize an electric wire/cable having a semiconducting layer with excellent radiation resistance.

Claims (1)

[Claims] (1) In electric wires and cables in which a semiconductive layer is extruded and coated on a conductor or an insulator, the semiconductive layer contains 20 parts by weight or more of conductive carbon black per 100 parts by weight of aromatic polyetherketone. An electric wire/cable characterized by being formed from a semiconductive composition.