JP2001043737A - Resin admixture for intervention for electric cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide good leading performance and separating performance by a resin intervention by constituting it from specified amount of polyvinyl chloride and the specified amount of fly ash. SOLUTION: A resin admixture for intervening material for an electric cable is composed of polyvinyl chloride of 100 pts.wt. weight and fly ash of 10 to 100 pts.wt. Base resin of the admixture is polyvinyl chloride, the degree of polymerization is not particularly limited, if extrusion molding is possible. FlY ash to be added is coal ash, mainly produced as a by-product from a thermal power plant, and made of ashen powdered coal. The chemical components and physical characteristics are stipulated by industrial standard (JISA6201) and may be appropriately selected from it. DOP is added as plasticizer to the admixture. The plasticizer does not depend much on the adding amount. As necessary, fire retardant, colorant, processing aid can be added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intercalation resin mixture used as an interposition of an electric cable.

[0002]

2. Description of the Related Art When manufacturing a large-diameter electric cable by twisting a plurality of insulated wires, generally, in order to fill gaps between the insulated wires and to ensure roundness of the core portion, generally, The sheath (outer skin) is covered with the interposition between the insulated wires.

The characteristics required for the interposition include not only that the gap is filled as described above to ensure the roundness of the core portion, but also that the specific gravity is low so that the entire cable is not heavy. It is required to have good tapping properties such as easy cutting when processing the cable terminal. Conventionally, various types of such interventions have been proposed, such as paper and resin.

[0004]

However, paper-made ones have the advantage that they are weak in strength and can be easily cut at the time of processing a cable terminal (having good tapping properties).
In the manufacturing process, it is necessary to wrap the paper material, which increases the size of the equipment.The moisture absorption of the paper also makes it easier for the insulator to absorb moisture, which may reduce the insulation performance of the cable. Further, there is a problem that a drying step is separately required due to the hygroscopicity of the paper.

[0005] On the other hand, in the case of resin, compared with paper winding, molding is carried out at the same time by simultaneous extrusion with a sheath material, so that it is possible to avoid an increase in the size of equipment and to solve the problem of hygroscopicity due to the characteristics of the resin. However, depending on the resin material used and its composition, it cannot be easily cut at the time of processing the cable end (poor tapping property), and it cannot be easily peeled off by tightly contacting the cable sheath side more than necessary ( In some cases, problems such as poor releasability) and poor extruding itself (poor extrudability) may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and provides a resin mixture for electric cable interposition excellent in leadability, releasability and extrudability as a resin interposition. It is something you want to do.

[0007]

According to the present invention, 100 parts by weight of polyvinyl chloride and fly ash 10 are provided.
To 100 parts by weight of the resin mixture for interposition of an electric cable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The base resin of the mixture of the present invention is polyvinyl chloride (PVC), and its polymerization degree is not particularly limited as long as it can be extruded.

The fly ash added to the polyvinyl chloride of the base resin is coal ash, which is mainly produced as a by-product from a thermal power plant or the like and is made of gray-white pulverized coal. Its chemical components and physical properties are based on industrial standards (J
ISA6201), and may be appropriately selected from these.

When this fly ash is added to polyvinyl chloride in an appropriate amount, when incorporated into a power cable as an intervening material, the tapping property and the peeling property are improved. High extrudability.

Then, the amount of the fly ash
If the amount is 10 to 100 parts by weight with respect to 100 parts by weight of polyvinyl chloride, if it is less than 10 parts by weight, it is difficult to cut the interposition itself, so that the extruding property is poor, and the releasability from the cable sheath side is also poor. Because it becomes. On the other hand, if it exceeds 100 parts by weight, it becomes difficult to extrude the resin itself, and the extrudability deteriorates.

To the admixture of the present invention, for example, di- (2-ethylhexyl) phthalate (DOP) or the like is added as a plasticizer because polyvinyl chloride is used as a base resin. Of course, the present invention is not limited to this DOP, and other plasticizers can be added. With the plasticizer, the above-mentioned properties can be obtained without being largely dependent on the amount of the plasticizer added. Further, if necessary, a flame retardant, a coloring agent, a processing aid, and the like can be appropriately added according to the required characteristics of the intervening.

<Examples> Table 1 shows Examples (1 to 3) of the resin mixture for inclusion according to the present invention and Comparative Examples (1 to 3) of the resin mixture for inclusion lacking the requirements of the present invention. In addition to the respective mixing ratios, an example of paper-made interposition (Comparative Example 4) was also shown, and a sample power cable was manufactured using each of the resin mixture for interposition and the paper-made interposition.

More specifically, in the case of the sample power cable, first, an insulated wire in which a stranded conductor having a cross-sectional area of 2 mm ^{2 made} of seven copper wires is coated with a cross-linked polyethylene insulator by water cross-linking, Three of these insulated wires were twisted to form a cable core, and then an interposition made of the above resin mixture for interposition was extruded on the outer periphery of the cable core simultaneously with a sheath made of soft PVC. In addition, in the case of paper-made interposition, it was wound so that the thickness of the sheath was the same and the outer diameter of the cable was equal. Table 1 also shows the characteristics (tensile strength = TS,
Tensile elongation = EL. , Hygroscopicity, extrudability, peelability, and extrudability).

The weight of the trowel was measured after the power cable of each sample was immersed in warm water of 70 ° C. for 24 hours and dried at 105 ° C. × 3 hours (%). ). In addition, the tapping property was determined by actually tapping the power cable of each sample and by the ease of intervening cutting. Those that could be cut most easily were indicated by ◎, those that could be cut easily were indicated by ○, and those that could not be cut most easily were indicated by x.

The releasability was determined by the ease of separation between the insulator and the sheath and the interposition. Those that could be peeled most easily were indicated by ◎, those that could be easily peeled were indicated by ○, and those that could not be easily peeled were indicated by Δ. The extrudability was determined based on the degree of resin breakage and large roughness when the extrusion temperature at the time of the above-mentioned interposition was set to about 150 ° C. In the best condition, there was almost no resin breakage or large roughness, and in the best condition, ○ was shown. When the resin breakage or large roughness was most noticeable, x was shown.

[0017]

[Table 1]

From the above Table 1, it can be seen that Examples (1 to 3) of the present invention are shown.
It can be seen that the sample has low hygroscopicity and is excellent in all of the properties of extrudability, peelability and extrudability. In contrast, comparative examples (1 to 1) lacking the requirements of the present invention
In the case of 3) and Comparative Example 4 made of paper, it can be seen that there is a defect in any of the characteristics.

[0019]

As is clear from the above description, according to the resin mixture for interposition of the electric cable of the present invention, an appropriate amount of fly ash is added to polyvinyl chloride as the base resin. When a power cable is formed, excellent properties can be obtained in all of the leadability, peelability and extrudability. Of course, since the interposition is made of resin, the hygroscopicity of the interposition itself is small, and the drying step and the like can be omitted.

Claims (1)

[Claims] 1. A resin admixture for electric cables, comprising 100 parts by weight of polyvinyl chloride and 10 to 100 parts by weight of fly ash.