JPS5935315A - Electric insulator for electric wire and 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 The present invention relates to an electrical insulator for electric wires and cables that can suppress the occurrence of water trees.

Since cross-linked polyethylene has a high degree of electrical insulation, it has been widely used as an insulator for electric wires and cables.

However, when cross-linked polyethylene insulated wires and cables are used in a humid or flooded atmosphere, water trees occur in the insulator, significantly reducing electrical insulation performance.

Water trees are caused by mites, foreign matter, etc. in cross-linked polyethylene insulation.
It also occurs when water condenses in local high electric field areas such as irregularities at the interface between an insulator and a semiconducting layer. Therefore, much effort has been made to eliminate these defects in wire and cable insulation, and improvements in resin quality control and wire and cable manufacturing technology have improved the effectiveness of water tree prevention. ing.

However, it is not possible to completely eliminate these defects with the current technology, and measures to suppress the occurrence of water trees have been studied from various angles.

The present invention has been made based on the above, and is an electric wire/cable electric wire that can suppress water tree generation even if there are defects such as voids P in the insulator, foreign matter, and irregularities at the interface between the insulator and the semiconducting layer. Its purpose is to provide an insulator.

That is, the electrical insulator of the present invention comprises l IJ ethylene,
0.1 to 100 parts by weight of anionic fluorosurfactant to 100 parts by weight of the ethylene copolymer or a mixture thereof.
This composition is obtained by crosslinking a composition in which 3.0 parts by weight of the compound is added.

In the present invention, conventionally known polyethylene or ethylene copolymer is used as the base resin,
Depending on the case, these may be used in combination. Ethylene-based copolymers include ethylene-vinyl acetate copolymers,
Examples include ethylene/ethyl acrylate copolymer, ethylene/butene-1 copolymer, and ethylenezolopyrene rubber, and these may be used alone or in combination of two or more.

A typical nonionic fluorosurfactant added to the base resin mentioned above is a fluorinated alkyl ester compound having a hydrophilic ester group and a hydrophobic fluorinated alkyl group, which is rL(aF '2) It has a chemical structure of n 0OOR'.

Here, It is H, OF3 is an alkyl group, it' is a short-chain alkyl group, and 0 is an integer of 1 or more.The amount of the nonionic fluorosurfactant added to the base resin is: The amount is 0.1 to 3.0 parts by weight based on 100 parts by weight of base resin/gin.

If it is less than 0.1 part by weight, the effect of inhibiting water tree generation is small;
This is because if the amount exceeds 30 parts by weight, a phenomenon of precipitation from the inside of the insulator to the surface is observed.

The composition thus obtained is crosslinked by chemical crosslinking using an organic peroxide, irradiation crosslinking using ionizing radiation, or silane water crosslinking using a silane compound.

Note that there is no problem in adding an antioxidant, a lubricant, a coloring agent, etc. to the above composition as necessary.

Examples of the present invention will be described below in comparison with comparative examples.

A sheet was prepared by kneading the composition shown in Table 1 using an 8-inch mixing roll, and the sheet was pelletized using a pelletizer. The wavelet is then introduced into the extruder,
A copper conductor with an outer diameter of 3 scales was extruded and coated with a polyethylene semiconductive layer of 0.5 wn thickness so that the insulator thickness was 2 mm, followed by dry crosslinking using nitrogen gas as a heating medium. An insulated wire was obtained by crosslinking in the tube and then cooling under pressure.

The lower column of Table 1 shows the results of observing the occurrence of water trees in the thus obtained insulated wire and the precipitation of the nonionic fluorosurfactant.

The observations were made as follows.

An insulated wire is immersed in distilled water, and 3
An alternating current voltage of KV, 50H2 was applied at room temperature for 18 months. After the electrification was completed, the insulator was cut into thin rings, boiled and stained with a methylene blue aqueous solution, and the number of water trees generated was observed using an optical microscope. In addition, the wire surface was visually observed and analyzed using infrared absorption spectroscopy after the energization was completed, and the precipitation of nonionic fluorine-based surfactants was investigated.

In Table 1, in Examples 1 to 6, the fluorinated alkyl ester compound was added in the amount specified in the present invention, and the occurrence of water trees was sufficiently suppressed and the surface of the insulator of the surfactant was added. No precipitation was observed.

On the other hand, Comparative Examples 1.2 and 2 are outside the scope of the present invention, and are insufficient in terms of inhibiting effect on water tree or precipitation of surfactant on the surface of the insulator.

Note that the reference example is a conventional insulated wire to which no surfactant is added.

Although the mechanism by which the nonionic fluorosurfactant suppresses water tree in the present invention is unknown, the addition of this agent increases the affinity between the base resin and water, diverting water concentrated in defective areas to other areas. It is presumed that this is for the purpose of dispersion. Furthermore, the fluorinated alkyl group is hydrophobic, which is presumed to improve the compatibility of this compound with polyethylene.

As explained above, the electrical insulator of the present invention is made by adding 01 to 30 parts by weight of a nonionic fluorine-based surfactant to 100 parts by weight of a base resin of polyethylene and/or ethylene copolymer. The composition is cross-linked to provide an insulator that has an excellent effect of inhibiting water tree generation and does not cause precipitation of field M11 occlusive agents on the surface, improving the reliability of lightning wires and cables. This greatly contributes to improvement.

Procedural Amendment C Poppy 1. Incident display Showa 51 JA Feng Gan No./Qt Kude I
No. a: Person making the amendment: 100 Phone number: Tokyo (216) 1611 (main representative): 5: Date of amendment order: 11/30/2016 6: Garment worker's call water: 1 glance at the clothing industry S Mijoq
Naε Suburbs n BJ finished 6 intuition/answer I, L 7 Famous mountain'sho n ljl bath hawk I
h-tari and one #-waku

Claims (2)

[Claims] (1) A composition obtained by adding 0.1 to 3.0 parts by weight of a nonionic fluorine-based surfactant to 100 parts by weight of polyethylene, ethylene-based 4-polymers, or a mixture thereof is crosslinked. An electrical insulator for electric wires and cables, characterized by comprising: (2) The electric wire/cable according to claim 1, wherein the nonionic fluorosurfactant is a fluorinated alkyl ester compound having a hydrophilic ester group and a hydrophobic fluorinated alkyl group. Electrical insulator for use.