JPS6288212A - Water-sealed pvc insulated wire - 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 Application Field> The present invention relates to a watertight vinyl insulated electric wire filled with a watertight compound and used as an overhead distribution line or the like.

<Prior art> Conventionally, in electric wires used for overhead distribution lines, by filling a watertight compound between the conductor and the insulator layer,
It is a common practice to prevent water from entering the conductor portion, eliminate corrosion and deterioration of the conductor, and obtain stable electrical characteristics over a long period of time.

In recent years, so-called dry type watertight electric wires using rubber or plastic resin-based watertight compounds have been increasing in consideration of workability and other aspects as watertight compounds for such uses.

Materials that have a relatively proven track record for this dry type watertight compound include EVA (ethylene-vinyl acetate copolymer) and EEA (ethylene-ethyl acrylate copolymer), and these compounds have already been used. Polyethylene insulated wire is provided.

Here, EVA and EEA are often used because, in addition to the important property that these resins have good adhesion to both the conductive metal and the polyethylene of the insulating layer,
Melt index (MT) and vinyl acetate content: I (
This is because various grade products with different values (VA%), ethyl acrylate content (EA%), etc. are available commercially, and they have advantages such as a wide range of selection and ease of use during processing.

<Problems to be solved by the invention> However, even with the excellent EVA and EEA as described above, they have poor adhesion to polyvinyl chloride resin, and only the polyvinyl chloride peels off when the terminal is exposed. However, there was a problem in that the watertight compound remained on the conductor, significantly reducing workability.

For this reason, in this type of insulated wire, E V AJPEE
A was not used as a watertight compound.

Therefore, the present inventors conducted various experiments and research in order to obtain a vinyl insulated wire using EVA or EEA as a watertight compound, and came to the following conclusion.

In other words, if a watertight compound is used that is a mixture of EVA, EEA, or both and a vinyl adhesive resin and has a melt flow ratio (MFR) of 15 to 300, this watertight compound and polyvinyl chloride can be mixed together sufficiently. It was found that it was attached to

The present invention was invented based on such research results.

The present invention, which is a means for solving these problems and its effects, is a stranded wire conductor made of a kneaded product of EVA or/and EEA and a vinyl adhesive resin, which has a melt flow ratio of 15 to 15.
Water that is 300! Watertight vinyl filled with compound and made of polyvinyl chloride as an insulator! T! ! It's on the edge wire.

In the present invention, since the watertight compound is used as a kneaded material with special characteristics, the watertight compound and the insulating polyvinyl chloride are well bonded to each other.

An example of the electric wire of the present invention is shown in Fig. 1.
The stranded conductor 1 consists of a central strand 1a, 6 layers of strands 1b..., and 12 layers of strands IC..., and each of these strands 1a, lb..., lc...・A watertight compound 2 having a melt flow ratio of 15 to 300 is filled in between, which is a mixture of EVA or/and EEA and vinyl adhesive resin, and the outermost part is covered with an insulator 3 made of polyvinyl chloride. There is.

Here, when filling the watertight compound, after press-fitting it between the stranded wire conductors using an extruder, the polyvinyl chloride insulator is extruded (tandem method), or as a more preferable method, the watertight compound and the polyvinyl chloride insulator are It is preferable to fill and cover by 2N co-extrusion (two-layer time extrusion method).

Examples of the vinyl adhesive resin used in the present watertight compound include polyester resins, carboxylic acid metal salt grafted resins, chlorinated polyethylene, polyvinyl chloride-vinyl acetate-polyethylene terpolymers, and the like. Commercially available products include Elvaloy (manufactured by DuPont Mitsui Polychemicals), N-Polymer (manufactured by Dango Kagaku),
Hymilan (manufactured by Mitsui Petrochemicals), Atmar (manufactured by Mitsui Petrochemicals), Sumigraft (manufactured by Sumitomo Chemical), HPR (manufactured by Sumitomo Chemical),
(manufactured by DuPont Mitsui Polychemical Co., Ltd.), etc.

With this watertight compound, the vinyl adhesive resin and EV
The reason for appropriately kneading A and/or EEA is that the vinyl-based adhesive resin alone does not only adhere well to polyvinyl chloride, but also has too good adhesion to conductor metals, so the watertight compound will not adhere well to conductors when stripping the insulator. There is a risk that EVA or EEA may remain on the surface.
This is because, in terms of filling, there is no preferable high MFR brand, and it is difficult to fill the stranded wire conductor sufficiently. Therefore, both of these are kneaded, and by this kneading, the melt flow ratio (MFR) is increased to 15 to 3.
The reason why it is set as 00 is that when the melt flow ratio is less than 15,
The stranded conductor is not filled with watertight compound enough,
Furthermore, if the melt flow ratio exceeds 300, there is a risk that the watertight compound will soften at high temperatures and drip from the terminals.

In addition, if the watertight compound is not sufficiently filled to the center of the conductor, apply watertight compound to the center wire in advance to increase the gap between the wires on the outer layer side, or make sure that the compound is sufficiently softened during filling. It is advisable to take measures such as preheating the stranded conductor to this temperature.

Further, appropriate amounts of carbon blank, anti-aging agent, rust preventive agent, etc. can be added to the watertight compound, if necessary.

<Example I> 100 parts by weight of EVA or EEA was mixed with 20 parts by weight of maleic anhydride grafted EVA (Mikata DuPont Polychemicals, trade name: HPR, MFR=8) to prepare a watertight compound.

The MFR of this watertight combination is based on EVA or EEA.
By varying the values, products within the range shown in Table 1 were obtained.

The watertight compound thus obtained and the polyvinyl chloride insulator (covering thickness: 1, 4 mm) were made into a 60 mm" stranded copper conductor (1 wire/6 wire/12 wire configuration) using an extruder. By simultaneously extruding two layers at a temperature of 180° C., vinyl insulated wires (Comparative Measurement 1, Examples NCL 2 to 5, Comparative Example No. 6) were obtained.

The following tests were conducted on each of these electric wires, and the results are also listed in Table 1.

Watertightness Test> A water pressure of 1 kg/am'' was applied from one end of a 2 m long electric wire, and 24 hours later, the presence or absence of water leakage from the other end was examined.

(Dripping test) One end of a 13 m long electric wire was opened within 3 cm in length, hung vertically in a constant temperature layer with the opened part facing down, and heated to 80°C.
After heating for 24 hours, the presence or absence of dripping of the watertight compound was examined.

Peeling test> The presence or absence of watertight compound remaining on the conductor when the wire insulation was stripped using a wire stripper was tested three times.

<Example 2> 20 parts by weight of various vinyl adhesive resins shown in Table 2 were kneaded with 0 parts by weight of EVA I O to obtain various watertight compounds. The MFR of these watertight compounds was adjusted to about 100 by selecting the MFR of EVA and vinyl adhesive resin.

Each of these watertight compounds is filled into a stranded copper conductor to form a vinyl insulated conductor (the structure is the same as in Example
-11, Comparative Examples m12-13) were prepared. At this time, the following two methods were used to fill the watertight compound.

<Tandem method> After filling the conductor with a watertight compound at a temperature of 180°C, a polyvinyl chloride insulator was extruded and coated with an extruder at the same temperature (180°C).

<Two-layer coextrusion method> A watertight compound and a polyvinyl chloride insulator were coated by simultaneously extruding 2N at 180° C. using an extruder.

Each of the electric wires was subjected to the JX1 test, water tightness test, and dripping test in the same manner as in Example I above, and the results are also listed in Table 2.

<Effects of the Invention> As is clear from the above explanation, according to the present invention, EV
Since a watertight compound made by kneading vinyl adhesive resin with A or/and EEA is used, the adhesion between the polyvinyl chloride insulator and the watertight compound is improved, and as a result, an insulated wire with good peelability can be obtained. . In addition, since the MFR of the watertight compound is set at 15 to 300, the compound has good filling properties and has moderate adhesion to the conductor.
Furthermore, it is possible to obtain an excellent watertight vinyl insulated wire without compound dripping even at high temperatures.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a vinyl insulated wire according to the present invention. In the figure, 1... Twisted wire cylinder, LA, LB, LC--Element wire, 2... Watertight compound, 3... Insulator.

Claims (1)

[Claims] Watertight, characterized in that the stranded wire conductor is filled with a watertight compound that is a mixture of EVA or/and EEA and vinyl adhesive resin and has a melt flow ratio of 15 to 300, and the insulator is polyvinyl chloride. Vinyl insulated wire.