JPS6147016A - Ant preventive 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 [Industrial Field of Application] The present invention relates to electric wires and cables provided with termite resistance.

[Conventional technology] Electrical wires and cables for control, power, communication, etc. buried underground in white wax habitats or laid underground conduits are damaged by termites, resulting in major problems in energy and information transmission. An accident has occurred.

As a countermeasure against such accidents, termite-proof electric wire cables having a structure in which nylon is provided in the outermost sheath of mli cables have been put into practical use in recent years.

Nylon's termite-proofing properties are said to be due more to its physical hardness than its chemical composition, and in fact, rigid plastics such as epoxy, polycarbonate, and polyacetal have been proven to have excellent termite-proofing properties.

As described above, nylon has reliable termite-proofing properties, and this nylon is applied as the outermost sheath of electric wires and cables by extrusion or tape wrapping.

On the other hand, for wires and cables installed underground or in conduits, including these anti-eRN wires and cables, damage to the wires and cables may occur after the wire and cable installation work is completed or during actual use.
Withstanding voltage tests and insulation resistance tests are increasingly being performed not only on insulators but also on sheaths in order to confirm the integrity of cables, such as checking for damage, alteration, deterioration, etc.

Among these, in particular, it is necessary to measure the withstand voltage and insulation resistance characteristics of the sheath portion by providing appropriate electrodes inside and outside the sheath. The electrode inside the sheath can generally use a gold scrap layer as the external shielding EWi of the cable, but the external electrode outside the sheath can be a metal tape or metal braid, but such a gold horse electrode can be used over the entire length of the cable. There are problems not only economically, but also in terms of ease of handling and installation work. Until now, with vinyl or polyethylene sheaths, methods such as coating the surface with conductive paint or extrusion coating with conductive compound have been used. has been taken.

[Problems to be solved by the invention Regarding electric wires and cables with a nylon sheath on the outermost layer, compounds or coatings that can be used as external electrodes have not yet been developed or put into practical use. ?141 There is a problem in that it is not possible to measure the withstand voltage or insulation resistance of the tocaple sheath.

In particular, in electric wires and cables where high A5 degree polyethylene is used as a sheath without a nylon termite layer on top, there is some concern about the integrity of such sheaths, as high concave polyethylene is susceptible to thermal or environmental stress cracking. Grasping is extremely important, and an electrode material suitable for nylon is desired.

The present invention is based on the above, and uses a conductive WJ that functions as an external electrode that enables the measurement of the withstand voltage or insulation resistance of the sheath of termite-proof wires and cables having a nylon sheath. The purpose is to provide a new termite-proof FFI wire/cable equipped with l.

[Means for Solving the Problems] The electric wire/cable of the present invention is made by providing a nylon layer on the outer periphery of a plastic or rubber sheath, and further adding carbon black to a mixture containing alcohol-soluble nylon and an epoxy compound on the outer periphery. It is characterized by being coated with a conductive paint.

The sheath material of the present invention may be either plastic or rubber, and includes polyethylene, polyvinyl chloride, chloroprene, ethylene propylene, and the like.

Examples of nylon include nylon 6.66.610 and nylon 11.12, and nylon 11.12 is preferred in consideration of termite resistance, processability, hygroscopicity, and handleability.

Of course, as long as the material is mainly composed of nylon, it may be a copolymer or a blend.

The thickness of the nylon layer varies depending on the size of the cable, but it is generally about 1 liter thick, and may be thinner for small cables and thicker for large cables. be.

Alcohol-soluble nylons include those that are soluble in lower aliphatic alcohols such as methanol and ethanol, and mixtures of these alcohols and chlorinated hydrocarbons such as trichlene.

Alcohol-soluble nylon is made by copolymerization or ternary copolymerization of raw materials.For example, 6/66/61
There are 0.6/66/11.6/66/12, etc. Also,
Low gal nylons such as nylon 11.12 are also soluble in alcohol.

In addition to such copolymers, alcohol-soluble nylons such as N-alkoxymethyl-modified nylons, in which nylon is treated with formalin, alfur, etc., to replace hydrogen in amide groups, are also used.

In short, the composition of nylon is not limited as long as it is soluble in a solvent mainly composed of alcohol.

Examples of epoxy compounds include bisphenol A type epoxy Epikote 828 (trade name of Shell Chemical Co., Ltd.), novolak epoxy DER-438 (trade name of Dow Chemical Co.), and tetrafunctional epoxy 7-raldite Ml-720 (trade name of Dow Chemical Co., Ltd.).
(Ciba Geigy product name).

The mixing ratio of alcohol-soluble nylon and epoxy compound is not particularly limited, but a range of 8:2 to 2:8 is particularly good.

Examples of carbon black for imparting conductivity include channel black, furnace black, and acetylene black. The haze is 50 to 300 parts by weight for 100 parts by weight of the mixture of alcohol-soluble nylon and epoxy compound.
Parts by weight are preferred.

A composition containing alcohol-soluble nylon, an epoxy compound, and carbon black is used as a paint by dissolving it in a suitable solvent such as ethyl alcohol or a mixed solution of ethyl alcohol and trichlene.

[Example] An OF cable in which a copper salt body of Example 1000w1 is wrapped with insulating paper, an aluminum sheath is applied to the circumference of the sample-yoar impregnated with insulating oil, and a polyvinyl chloride sheath is coated on the outer circumference with a thickness of 711I11. It was used.

Apply nylon 11 to a thickness of 1 on the outer periphery of the polychloride sheath.
．． Extrusion coated on 0ag+.

Subsequently, 10! of acetylene black was added to a mixture consisting of a ternary copolymerized nylon etim part consisting of nylon 6/66/610 and 4 parts by weight of bisphenol A type epoxy.
! [1a11 was added and a conductive paint prepared by diluting this with 80 weight IJ of ethyl alcohol was applied.

The conductivity of the conductive layer was 85Ω-α, which was a sufficient value as an external electrode for measuring the withstand voltage and insulation resistance of the sheath.

Aluminum sheath and conductive layer of this cable (large J1!I)
As with the withstand voltage test in the FD, the insulation resistance calculated back from the leakage current was measured, and sufficient electrode action was confirmed.

Meanwhile, connect the cable with two layers of dry cloth tape and lubricated cloth tape.
When the abrasion test was carried out 20 times using two tapes, both tapes showed no peeling of the paint, Ia! No chafing occurred.

Comparative example The same OF cable as in the example was used.

1.0 nylon 11 on the outer periphery of the polychloride and nil sheath
It was applied to am.

Subsequently, a conductive paint consisting of 10 parts by weight of vinyl chloride vinyl acetate copolymer and 80 parts by weight of a 2=1 mixed solvent of acetylene black 101 metal ethyl ketone and perchlorethylene was applied.

It was confirmed that the conductivity of the conductive layer was 60Ω, and that it could be sufficiently used as an external electrode.

However, in the dry cloth tape and wet cloth tape abrasion tests, the paint layer on the nylon sheath disappeared after 6 and 4 times, respectively.

[Effects of the Invention] As explained above, the present invention provides 11I-proof electric wires and cables coated with a conductive paint that is extremely advantageous for discovering defects, abnormalities, etc. in sheaths after manufacture, transportation, and installation. becomes possible.

Claims (1)

[Claims] (1) A nylon layer is provided on the outer periphery of the plastic or rubber sheath of the electric wire/cable, and a conductive paint made of a mixture containing alcohol-soluble nylon and an epoxy compound with carbon black added is coated on the outer periphery. Anti-termite wires and cables.