JPH04370605A - Insulated wire and cable - Google Patents

Abstract

PURPOSE:To obtain a polypropylene-based insulated wire, or cable having no disconnection of a molecular chain in crosslinking and high melting point by providing the external area of a conductor with the crosslinking insulating layer of a propylene-diene copolymer having a specific content of diene. CONSTITUTION:An insulated wire, or cable is formed by providing the external area of a conductor with the crosslinking insulating layer of a polypropylene- diene copolymer. And, diene uses butadiene, isoprene, etc., to obtain its content of 0.5-10mol%. Where, in a diene content of less than 0.5mol%, crosslinking efficiency decreases. When the diene content exceeds 10mol%, the meeting point of polypropylene drops. And, the polypropylene uses homopolypropylene having high melting point. Thus, tire insulated wire or cable having no disconnection of a molecular chain in crosslinking and high melting point can be obtained by using the propylene-diene copolymer for the crosslinking insulating layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in insulated wires, particularly insulated wires and cables made of crosslinked polypropylene polymers, which are suitable for use as low- and medium-voltage wires and cables.

0002

[Prior Art] Cross-linked polyethylene (XLPE) is widely used as an insulating material for electric wires and cables, but since cross-linked polyethylene usually uses low-density polyethylene (LDPE) as a base resin, it has a low melting point of 105°C to 11°C.
At temperatures above 0°C, it softens into a rubbery state. Therefore, for use at higher temperatures, it is desirable to use a resin with a high melting point as the base resin and crosslink it.

0003

[Problems to be Solved by the Invention] Polypropylene is an example of a resin with a high melting point, but since polypropylene has tertiary carbon, its molecular chains are cut prior to crosslinking, making it difficult to form crosslinked insulated wires and cables. I couldn't get it. The present invention aims to solve these problems.

0004

[Means for Solving the Problems] The present invention was developed as a result of intensive studies to solve the above-mentioned problems, and the outline thereof is as follows. An insulated wire/cable characterized by having a crosslinked insulating layer of a polypropylene-diene copolymer with a diene content of 0.5 to 10 mol% provided on the outside of the conductor.As the diene to be copolymerized with propylene, butadiene, isoprene, etc. are used. Can be mentioned. The diene content is 0.
A content of 5 to 10 mol % is effective; if it is less than 0.5 mol %, the crosslinking efficiency deteriorates, and if it exceeds 10 mol %, the melting point of the polypropylene decreases and the characteristics of a high melting point resin are lost. The polypropylene constituting the copolymer includes homopolypropylene and block polypropylene, and homopolypropylene is preferable because of its high melting point. As a crosslinking method, any of chemical crosslinking using an organic peroxide, irradiation crosslinking using an electron beam, and radiation can be used. The insulator may also contain additives such as antioxidants, flame retardants, copper inhibitors, fillers, and the like. It is also possible to use a blend of other polyolefins such as polyethylene or copolymers thereof.

[0005]

[Example] As an example of the present invention, the diene content was 3 mol%.
As a comparative example, a polypropylene-diene copolymer (homopolypropylene base, melting point 151°C, MI = 2 g/10 min) was used, and ordinary homopolypropylene, which has the same melting point and MI as the above example, was used. After cross-linking and electron beam irradiation cross-linking, the conductor cross-sectional area is 38 mm2,
An insulated wire with an insulation thickness of 2 mm was manufactured. However, the insulating layer contains 0.3 parts by weight of a phenolic antioxidant and 0.5 parts by weight of a triazole-based copper damage inhibitor per 100 parts by weight of the resin. Example 1 and Comparative Example 1 As a crosslinking agent, 1.5 parts of 2.5 dimethyl-2.5 di(t-butylperoxy)hexane was added to 100 parts by weight of the resin.
After adding 5 parts by weight and extruding at 160°C, 10 kg/cm
2. Crosslinking was performed through a N2 gas crosslinking tube at 230°C. Example 2 and Comparative Example 2 10Mra using an electron beam irradiation device with an accelerating voltage of 750kv
Crosslinking was performed by irradiation with electron beam d. The gel fraction of the insulated wires obtained as described above was measured in both Examples and Comparative Examples. The results are shown in Table 1, and the gel fractions of the Examples of the present invention were all high, whereas the gel fractions of the Comparative Examples were 0.

[0006]

[Table 1]

[0007]

As explained above, by using a propylene-diene copolymer in which a diene is introduced into propylene, polypropylene-based insulated wires and cables with a high melting point can be provided.

Claims (1)

[Claims] Claim 1: The outside of the conductor has a diene content of 0.5 to 1.
An insulated wire/cable characterized by being provided with a crosslinked insulating layer of 0 mol% propylene-diene copolymer [Claim 2]
] The insulated wire/cable according to claim 1, wherein the crosslinking is performed by organic peroxide, electron beam, or radiation irradiation.