JPS5966007A - Flame resistant 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 twist-resistant electric wires and cables that do not generate halogen gas during combustion.

Ethylene propylene copolymers and polyethylene-based polymers, which have excellent electrical insulation properties, are often used as insulating materials for electric wires and cables, and the recent trend is to use UL standard VW-1 for electric wires and cables for nuclear power plants and electric wires for vehicles.
There has been a strong demand for a high level of twist resistance.

Methods of making such polymers difficult to twist have been used by mixing halogen-containing compounds, antimony trioxide, phosphorus-containing compounds, etc., but these produce a large amount of smoke in the event of a fire and are toxic to the human body. It is considered a problem because it generates gas.

In light of this situation, inorganic aquariums that emit very little smoke and no toxic gases are attracting attention.

Magnesium hydroxide, which releases water of crystallization near the decomposition temperature of the polymer, is particularly effective in imparting VW-level high twist resistance.

However, in order to impart this high degree of twist resistance, it is necessary to add a large amount of magnesium hydroxide, which causes the serious problem of agglomeration of magnesium hydroxide, resulting in a decrease in dispersibility and tensile properties. was.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a twist-resistant electric wire/cable that has good dispersibility, tensile properties, and high twist resistance, and does not generate toxic halogen gas when burned. It's about doing.

To achieve this objective, the ethylene polymer 10
Electric wires and cables having cross-linked electrical insulation are coated with a mixture in which 150 parts by weight or more of magnesium hydroxide with an average particle size of 3 μ or less and a BET specific surface area of 151H2/g or less is added to 0 parts by weight. It was discovered that this method is extremely effective, leading to the present invention.

Examples of the ethylene polymer in the present invention include ethylene propylene copolymer, ethylene propylene diene terpolymer, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, and ethylene butene copolymer, which may be used alone or in combination of two or more. used.

The magnesium hydroxide used in the present invention must have an average particle size of 3 μ or less and a BET specific surface area of 5 m/g or less. If it is outside this range, agglomeration will occur during roll or Banbury kneading, resulting in poor extrudability. , the tensile properties deteriorate.

Further, it is necessary to mix 150 parts by weight or more of magnesium hydroxide with respect to 00 parts by weight of the ethylene polymer, and if it is outside this range, the desired twist resistance cannot be imparted.

The mixture of ethylene polymer and magnesium hydroxide is extrusion coated onto the conductor directly or through another insulator, and then crosslinked by heating, for example, in a steam atmosphere.

The crosslinking agent used is dicumyl peroxide, 3
-Organic peroxides such as bis(t-butylperoxysopropyl)benzene are suitable, along with sulfur, ethylene dimethacrylate, diallyl phthalate, p-quinonedioquineshim, etc. as crosslinking aids. You may.

Further, in the present invention, antioxidants, lubricants, softeners, dispersants, etc. may be added.

As antioxidants, phenyl-σ-naphthylamine,
Amine-based antioxidants such as N,N'-di-β-naphthyl-P-phenylenodiamine, phenolic antioxidants such as 2,6-di-1-butyl-4-methylphenol, and hindered phenol. etc. can be mentioned.

Examples of the present invention will be described below while comparing them with comparative examples.

6. A composition made by blending various ingredients as shown in Table 1.
A 40m/m extruder (k/D, -
25) on a copper wire with an outer diameter of 20 mm.
Various insulated wires were obtained by extrusion coating to a thick thickness and then holding in a steam atmosphere of 13 kg/cm2 for 3 minutes.

The results of the dispersibility, twist resistance and tensile properties after roll kneading of Examples and Comparative Examples are shown in the lower column of Table 1.

Dispersibility was determined by rolling out a sheet with a thickness of 1 mm after roll kneading.
Observation was made using a magnification microscope. To evaluate twist resistance, an electric wire held horizontally is exposed to a flame for 1 minute using a burner, and if it goes out within 1 minute, it passes VW-1, and if it burns for more than 1 minute, it fails. The tensile properties were determined by drawing the copper wire after steam crosslinking.
After being left in a constant temperature room at 0.degree. C. for one day, it was measured using a Schopper tensile tester at a tensile speed of 500 mm/min.

As can be seen from Table 1, in Examples 1 to 6, the dispersibility was good and no lumps were observed due to aggregation, and the twistability was OL.
It passes the VW-1 standard, and its tensile properties fully satisfy the 0.4 kg*mm2 electrical appliance standard for ethylene propylene rubber.

On the other hand, in Comparative Examples 1 and 2, the amount of magnesium hydroxide was less than the limit value, and the twist resistance was rejected.

Furthermore, Comparative Examples 3 and 4 used magnesium hydroxide whose average particle size and BET specific surface area were outside the limits, resulting in poor dispersibility and, as a result, a significant decrease in tensile strength.

As explained above, according to the present invention, good dispersibility,
Flame-retardant wires and cables that have tensile properties and high twist resistance and do not emit halogen gas harmful to twist resistance can be obtained, and have great industrial value.

Claims (1)

[Claims] (1) Covered with an electrical insulator made by crosslinking a mixture of 100 parts by weight of ethylene polymer and 150 parts by weight or more of magnesium hydroxide with an average particle size of 3 μ or less and a BET specific surface area of 15 u + 27 g or less. A wire/cable that is difficult to twist.