JPS59207504A - Crosslinked polyolefin insulated 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 The present invention relates to electric wires and cables having a crosslinked polyolefin insulation layer.

Cross-linked polyolefin insulated wires and cables are produced by introducing a resin composition made by adding a cross-linking agent, an antioxidant, and, if necessary, a lubricant, a weather resistance agent, a coloring agent, etc. to a polyolefin resin into an extruder. It is generally manufactured by extrusion coating the outer periphery of the conductor and then subjecting it to a crosslinking treatment.

In recent years, improvements in extruders have led to the adoption of extruders that are less susceptible to cross-linking effects.This has led to methods in which a crosslinking agent is injected into the extruder, or a method in which a solution containing an antioxidant is injected into the crosslinking agent. is proposed.

Compared to conventional methods, these manufacturing methods can omit the cross-wire process, improving manufacturing efficiency, and prevent contamination by foreign matter during cross-wire, leading to improved product characteristics.

The crosslinking agents used in this injection method include di-tert-butyl peroxide, tert-butyl cumyl chili-oxide, and 2,5-dimethyl-2,5-di(1-butylroot ξ), which are liquid at room temperature. -Okin)-
A crosslinking agent such as hexane-3 is used alone or in combination with solid tsucumyl.

As an antioxidant, 4, which dissolves in the crosslinking agent at room temperature,
4'-thiobis(6-t-butyl-3-methylfe/-
dilauryl dithiozolobionate 1,2,2-
Thio[diethyl-bis-3(3゜5-diethyl-t-)]
-]1-ru-4-hyProquinphenyl]propionate and the like are used alone or in combination.

However, liquid crosslinking agents have the disadvantage of discoloring the conductor due to impurities contained in the crosslinking agent or acidic decomposition products generated during crosslinking reactions.

Impurities contained in decomposition products and crosslinking agents,
Examples include cumyl alcohol, α-methylstyrene, cumene, tert-butanol, and acetophenone, and since these are all acidic substances, they promote discoloration of the conductor.

As a method of preventing conductor discoloration, it is possible to remove decomposition products during the drying process of electric wires and cables, but as the insulating layer becomes thicker, removal becomes more difficult.

Wrapping separator tape over the conductor still does not have sufficient effect.

The present invention is an improvement over the prior art described above, and aims to provide crosslinked polyolefin insulated wires and cables that can prevent conductor discoloration.

That is, the present invention uses 2,2'-oxamidobis-ethyl, 3 (3,5-)-) as a conductor discoloration inhibitor.
1) -Phthyl-4-hydroxyphenyl) flobionate is added and contained in a polyolefin resin together with a crosslinking agent and an antioxidant.

The above-mentioned conductor discoloration inhibitor is commercially available from Koniroyal under the trade name Naragard LX-1, and is an antioxidant having two phenol groups and two amine groups in its structural formula, and is suitable for use in electrical wires and cables. A remarkable effect is exhibited when copper conductors are used in twisted wires.

That is, common heavy metal maple deactivators are effective in areas that are in direct contact with copper, such as stranded wires.

When twisted into several layers, the internal conductor becomes discolored due to decomposition products of the crosslinking agent, which adversely affects electrical resistance.

However, when an antioxidant with a basic composition is added to polyolefin resin, it neutralizes the acidic decomposition products generated during the crosslinking reaction, converts them into a separate substance that does not contribute to discoloration, and also forms complex salts on the copper conductor. It acts to form and protect.

Even if the conductor is treated with tri-triazole or benzotriazole, which are commonly used as volatile rust preventives, no such effect is observed.

In the present invention, the method for uniformly dispersing the conductor discoloration inhibitor in the polyolefin resin is to knead both of them into pellets using Panpari or the like, or to make a master patch of both of them. There is a method of feeding the mixture into an extruder and dispersing it uniformly by kneading the extruder.

Suitable polyolefin resins include those containing a majority of ethylene, such as low-density polyethylene, medium-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-propylene copolymer. These may be used singly or in combination of two or more.

In the present invention, in addition to the polyolefin resin, crosslinking agent, antioxidant, and conductor discoloration prevention, lubricants, colorants, fillers, crosslinking aids, and the like may be added as necessary.

Examples and comparative examples of the present invention will be described below.

Example 0 Polyethylene (density = 0920, melt index 1
00 parts by weight: 1. O) 0 Naugat LX-10, 3 parts by weight 4.4'-Thiobis-(6-t-butyl-3-0 2 parts by weight methylphenol) 0 Tertyalyzotyl, cumyl...ξOki 20 parts by weight Side Of the above components A master patch of polyethylene and Naragat LX=1 was prepared and introduced from an extrusion-like hopper.

On the other hand, a solution in which 4,4'-thiobis-(6-t-butyl-3-methylphenol) was dissolved in tert-butyl cumyl peroxide was injected from the injection port near the foramina.

After uniformly kneading various ingredients in an extruder, the cross-sectional area is 200 m.
It was extruded and coated on a copper stranded wire conductor of 200 m2 in thickness to a thickness of 3, then held in water vapor of 20 Kg/cm2 for 10 minutes for crosslinking, and cooled under pressure.

This electric wire was wrapped around a drum at 20℃ for 4 hours and 9 hours.
A heat cycle of 4 hours at 0° C. was repeated 90 times, and the presence or absence of discoloration of the conductor was visually determined, but no discoloration was observed.

Comparative Example When a cable prepared by excluding Naragat LX-1 from the example was subjected to a similar heat cycle, discoloration of the conductor was clearly observed in the heat cycle at 90° C. for 4 hours.

As explained above, according to the present invention, conductor discoloration can be prevented, and a crosslinked polyolefin insulated electrical/cable with no adverse effect on electrical resistance can be obtained.

Claims (1)

[Claims] 1. A crosslinking agent that is liquid at room temperature for polyolefin resin,
An insulating layer of a resin composition containing an antioxidant and a conductor discoloration preventive agent is formed on the circumference of the conductor, and this insulating layer is used as the conductor discoloration preventive agent in crosslinked electric wires and cables. '-Oxaami 1 bis ethyl,
3 (3, 5--) -Tree-t-1-Lou 4-
A cross-linked polyolefin insulated wire/cable characterized by containing hydroquinphenyl) flobionate.