JPH0794038A - Vinyl chloride insulated wire for outdoor use - Google Patents

Abstract

PURPOSE:To improve watertightness and peeling property by filling a mixture of ethylene-vinyl chloride copolymer and an ethylene-vinyl acetate copolymer having respective specified mixing ratios and Ml values into a cavity between stranded conductors. CONSTITUTION:It is necessary that a watertight mixture 1 used in an outdoor vinyl chloride insulated wire has a mixing ratio of 5-30:95-70 by weight of ethylene-vinyl chloride copolymer to ethylene-vinyl acetate copolymer. When the mixing ratio of the ethylene-vinyl chloride copolymer is less than 5, the adhesive strength with a vinyl chloride resin insulator is not sufficient. When the mixing ratio exceeds 30, on the contrary, the adhesive strength with a stranded conductor 2 is reduced. When the MI value of the watertight mixture 1 is less than 5, the filling between the stranded conductors 2 of the vinyl chloride insulated wire is difficult. When the MI value exceeds 150, on the contrary, the kneading of the ethylene-vinyl acetate copolymer with the ethylene-vinyl chloride copolymer is difficult.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride insulated electric wire for outdoor use, which is obtained by filling a space between stranded wire conductors with a watertight admixture that adheres to both metal and vinyl chloride resin.

[0002]

2. Description of the Related Art Occasionally, a stress corrosion disconnection accident occurs in an outdoor high-voltage distribution line, an outdoor low-voltage distribution line, or the like. The cause is
Regardless of the environment, it is said that corrosive rainwater enters the voids between the twisted wire conductors of the distribution line and oxidizes the conductor wires, which is said to begin. Therefore, as one means for preventing the stress corrosion disconnection accident, a means for preventing the entry of rainwater and running water by filling a space between the twisted wire conductors with a water-tight mixture.

As a watertight admixture to be filled in the space between the twisted wire conductors of an insulated electric wire, an epoxy resin and a low molecular weight polyamide or polysulfide curing agent are added at the same time and the reaction between the two is completed to complete a rubbery watertight admixture. Water-tight as a material, low-viscosity rubber to which non-volatile oil, a vulcanizing agent and a vulcanization aid are added and vulcanized to make a water-tight rubber-like mixture, and polyisobutylene with high adhesiveness. Water-tight admixtures in which thermal expansion and contraction properties are improved by adding paraffin or petroleum jelly and inorganic powder or inorganic fibers are known. There is a problem in the filling work of the water-tight mixture into the space between the twisted wire conductors of the polyethylene insulated wire or cross-linked polyethylene insulated wire used in the above, or the water-tight mixture from the conductor of the insulated wire. EVA (ethylene-vinyl acetate copolymer) is currently used because it not only has the problem of being difficult to peel off, but also the adhesion of polyethylene resin and cross-linked polyethylene resin to the insulator is not preferable. Alternatively, EEA (ethylene / ethyl acrylate copolymer) or a dry-type water-tight mixture containing these blends as a main component is filled in the voids between the stranded conductors and is put to practical use as a water-tight outdoor high-voltage distribution line. ing.

[0003]

However, in the case of a vinyl chloride insulated wire which is often used as an outdoor low-voltage distribution line, even if EVA or EEA is used to fill the voids between the stranded conductors, the outer sheath is not covered. Since it hardly adheres to the vinyl chloride resin of the insulator, rainwater will run and it will not be sufficiently watertight, and when the insulator of the insulated wire is peeled off, only the insulator will peel off However, there was a problem that the water-tight mixture remained and hindered the connection.

Therefore, the present invention solves the conventional problems described above and provides an outdoor vinyl chloride insulated wire which is excellent in watertightness, has no stress corrosion breakage accident, and has good workability in electrical work. The purpose is to

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that ethylene.
The vinyl chloride copolymer and the ethylene / vinyl acetate copolymer have a weight ratio of 5 to 30:95 to 70 and an MI value of 5
The present invention has been completed by finding that the water-tightness is completely maintained by filling the space between the twisted wire conductors with the water-tight mixture in the range of 150 to 150.

The ethylene / vinyl acetate copolymer may be an ethylene / vinyl acetate copolymer which is usually used, but one having a low MI value or an extremely high MI value is not preferable.

The watertight admixture used in the outdoor vinyl chloride insulated wire according to the present invention comprises an ethylene / vinyl chloride copolymer and an ethylene / vinyl acetate copolymer in a weight ratio of 5 to 30:95 to 70. If the blending ratio of the ethylene / vinyl chloride copolymer is less than 5, the adhesive strength with the vinyl chloride resin insulator is not sufficient, and conversely the blending ratio is 30. If it exceeds 1.0, not only the adhesive strength with the vinyl chloride resin insulator is not improved so much, but also the adhesive strength with the conductor is lowered and the material cost of the watertight mixture is raised, which is not preferable.
The preferred blending ratio is ethylene / vinyl chloride copolymer 1
5 to 25, and ethylene-vinyl acetate copolymer 85 to 75.

Next, the MI value of the watertight mixture is 5 to 150.
If the MI value is less than 5, it becomes difficult to fill the voids between the stranded conductors of the vinyl chloride insulated wire. On the other hand, when the MI value exceeds 150, it becomes difficult to knead the ethylene / vinyl acetate copolymer and the ethylene / vinyl chloride copolymer. Considering such circumstances, a more preferable range of MI value is 15 to 60.

[0009]

The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited to these examples.

After kneading the compositions of Examples and Comparative Examples shown in Table 1 with a kneader to prepare chips of a water-tight mixture,
The results of preliminary tests for investigating the relationship between the adhesive strength between the vinyl chloride resin insulator and the watertight mixture and the relationship between the adhesive strength between the copper plate and the watertight mixture using the chip will be explained in the lower part of Table 1. .

Next, a method for adjusting the sample in the preliminary test will be described below. A. After preheating the chips of vinyl chloride resin mixture with insulation mixture for electric wire at 180 ° C for 3 minutes, press them at a pressure of 180 kg / cm ² for 3 minutes to make a sheet with a thickness of 2 mm. Preheat chips at 120 ° C for 3 minutes, then
A sheet of 2 mm is prepared by applying a pressure of 0 kg / cm ² for 3 minutes. After preheating both sheets at 180 ° C for 6 minutes, 1
The two sheets are joined by applying a pressure of 80 kg / cm ² for 3 minutes, punched with a dumbbell having a width of 25 mm and a length of 200 mm, and the joint at one end is cut open by about 20 mm with a small blade, and each end is cut. The adhesive strength by T-shaped tearing was measured at a pulling speed of 100 mm / min.

B. Width 25 mm, thickness 0.5 mm, length 200 mm
After degreasing the surface of the copper plate of No. 3 with a trichlene solvent, place it on the water-tight admixture sheet with a thickness of 2 mm described in A.
After preheating at ℃ for 6 minutes, press them at 180 kg / cm ² for 3 minutes to join them together, cut them out into the shape of a post-copper plate, cut the joint at one end about 20 mm with a small blade and autograph each end. The adhesive strength by T-shaped tearing was measured at a pulling speed of 100 mm / min.

[0013]

[Table 1]

As can be seen from the results in Table 1, Examples 1 to 1
The water-tight mixture of No. 4 is superior to those of Comparative Examples 1 to 3 in both adhesive strength with a vinyl chloride insulator and adhesive strength with a copper plate.

However, it is shown that the water-tight mixtures of Comparative Examples 1 to 3 also have sufficient adhesive strength with the vinyl chloride resin insulator and the copper plate.

Since the results shown in Table 1 are preliminary tests in the form of a sheet, it is necessary to fill the space between the twisted wire conductors of an actual vinyl chloride insulated wire with a watertight mixture to obtain sufficient watertightness. The result of the investigation as to whether or not is possible will be described below. The watertight admixture 1 having the compositions of Examples and Comparative Examples shown in Table 1 kneaded with a kneader was twisted with 19 pieces of 2.0 mmφ hard copper wire to fill a stranded wire conductor 2 having a conductor cross-sectional area of 60 mm ² , and A vinyl chloride resin insulator 3 having a thickness of 1.4 mm is coated on the top to produce a water-tight vinyl chloride insulated wire (see FIG. 1, but shown as a conceptual diagram). Table 2 shows the results of examining the filling properties between the stranded conductors.

[0017]

[Table 2]

Next, the above characteristic test will be described below. Water-tightness means that a vinyl chloride-insulated electric wire filled with a water-tight mixture is cut to 2 m and 0.5 Kg / cm ² from one end
After applying the water pressure for 24 hours and leaving it for 24 hours, the insulated electric wire is disassembled and the water penetration distance (cm) into the conductor is measured to determine the water tightness. Peeling property means that when the outer insulation layer of a watertight vinyl chloride insulated wire is peeled off with an electric knife, the watertight mixture is peeled together with the insulation layer and does not remain on the stranded conductor at all. Is preferred.

As can be seen from the results in Table 2, the water-tight admixtures used in Comparative Examples 1 and 2 are not preferable because leakage occurs. The watertight admixture of Comparative Example 3 shows good results in watertightness, but is inferior in peeling property and is not preferable in workability in electrical work.

However, the watertight admixtures used in Examples 1 to 4 show an excellent watertightness under a water pressure of 0.5 kg / cm ² after 24 hours, exhibiting an excellent watertightness and peeling. It can be seen that both the property and the filling property are good.

Although the outdoor vinyl chloride insulated wire according to the present invention is not shown in the examples, the watertight mixture is other than two components of ethylene / vinyl chloride copolymer and ethylene / vinyl acetate copolymer. In addition, a stabilizer, an antioxidant, a copper damage inhibitor, a colorant, a plasticizer and the like can be appropriately added and used.

[0022]

Since the outdoor vinyl chloride insulated wire according to the present invention is constructed as described above, sufficient watertightness is obtained, and the stress corrosion disconnection accident which has occurred in this type of insulated wire is prevented. This can be prevented in advance, and since the water-tight mixture is peeled together with the insulator when the jacket insulator of the insulated wire is peeled off, workability in electrical work is also improved.

Further, according to the present invention, it is possible to easily fill the space between the stranded wire conductors of the vinyl chloride insulated wire with the water-tight mixture to facilitate the production of the insulated wire. Since it is homogeneous, there is an advantage that it exerts the above-mentioned watertightness and peeling property more effectively.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an outdoor vinyl chloride insulated wire according to the present invention.

[Explanation of symbols]

1-watertight mixture, 2-stranded conductor, 3-vinyl chloride insulator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sumio Matsuno 2-3-1, Iwata-cho, Higashi-Osaka City, Osaka Prefecture Tatsuta Electric Wire Co., Ltd. (72) Inventor Shuichi Tsurumaru 2-3, Iwata-cho, Higashi-Osaka, Osaka No. 1 Tatsuta Electric Cable Co., Ltd.

Claims (1)

[Claims] 1. An ethylene / vinyl chloride copolymer and an ethylene / vinyl acetate copolymer in a weight ratio of 5 to 30:95 to.
An outdoor vinyl chloride-insulated electric wire having a water-tight mixture of 70 and an MI value in the range of 5 to 150 filled in the voids between the stranded wire conductors.