JPS61248308A - Flame resisting insulated wire - 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 [Industrial Field of Application] The present invention relates to a flame-retardant insulated wire that does not generate toxic halogen gas when burned.

[Prior Art] Polyolefins, which have excellent electrical insulation properties, have been widely used as insulating materials and sheath materials for electric wires and cables.

As a recent trend, there has been a strong demand for flame retardancy for electric wires and cables for nuclear power plants, electric wires for vehicles, and electric wires for wiring inside panels and machines.

As a method of making polyolefin flame retardant, a method of mixing a hexagen-containing compound, a phosphorus-containing compound, etc. has generally been adopted.

However, these produce a lot of smoke when burned, causing problems such as corrosiveness to equipment and toxicity to the human body. In particular, recently there has been a strong demand for not generating such halogen-based gas from a safety standpoint.

In light of this situation, inorganic flame retardants with extremely low smoke generation and toxicity have been attracting attention.

[Problems to be solved by the invention] However, in order to impart a high degree of flame retardancy, it is necessary to add a large amount of inorganic flame retardant, but if it is added in large quantities, mechanical stress such as bending and scratching may cause whitening. There is a problem that black materials tend to become easily colored, and this tends to be particularly noticeable in black materials.

The present invention has been made based on the above, and aims to provide a flame-retardant insulated wire that has a high degree of flame retardancy, prevents whitening due to mechanical stress, and does not generate toxic halogen gas, etc. It is something.

[Means for Solving the Problems] The flame-retardant insulated wire of the present invention consists of an insulator or sheath made of a flame-retardant electrical insulation composition containing polyolefin and an inorganic flame retardant, and a curable polybutadiene as a main component. It is characterized by providing a protective layer formed by curing the composition.

In the present invention, examples of the polyolefin include ethylene propylene copolymer, ethylene propylene genter polymer, polyethylene, ethylene vinyl acetate copolymer, nyletine ethyl acrylate copolymer, ethylene butene copolymer, and ethylene butene genter polymer, which may be used alone or in combination. It is possible to use a mixture of the above.

Examples of inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, hydrotalcites, and calcium hydroxide.

These may be used alone or in combination of two or more, or may be used in combination with talc, clay, calcium carbonate, etc.

The inorganic flame retardant is preferably mixed in an amount of 50 to 500 parts by weight based on 100 parts by weight of the polyolefin. 5
If it is less than 1 part by weight, the desired flame retardancy will not be imparted sufficiently, and if it exceeds 500 part by weight, the processability will be markedly reduced and extrusion molding will tend to become difficult.

In the present invention, in addition to the above components, crosslinking agents, antioxidants, lubricants, softeners, dispersants, etc. may be added as appropriate.

As a crosslinking agent, dicumyl peroxide, 3-bis(
An organic peroxide represented by t-butylperoxyisopropyl)benzene is suitable, and sulfur, ethylene dimethacrylate, diacrylphthalate, ρ-quinone dioxime, etc. may be used in combination with this as a crosslinking aid. .

As antioxidants, phenyl-α-naphthylamine,
Amine-based antioxidants such as N,N''-di-β-naphthyl-p-phenyrezinamine, 2,6-di-t-butyl-4
- Phenolic antioxidants such as methylphenol and hindered phenyl.

In the present invention, a protective layer mainly composed of curable polybutadiene is coated on the insulator or sheath made of the above-mentioned electrical insulating composition and cured to prevent whitening on the surface of the insulator or sheath. ing.

The curable polybutadiene in the present invention refers to polybutadiene having an allyl-type primary hydroxyl group and its terminally modified derivatives, and terminally modified derivatives such as isocyphnate, carboxyl group, epoxy group, acryloyl group, etc. can give.

Colorants, surfactants, antioxidants, photosensitizers, stabilizers, etc. may be added to this curable polybutadiene.

This curable polybutadiene has excellent flexibility and good adhesion to polyolefin, and can effectively protect the insulator or sheath.

Examples of means for curing the curable polybutadiene include ultraviolet irradiation, ionizing radiation irradiation, and heating.

[Example 1] Various components constituting the insulator were put into 6-inch rolls maintained at 100 to 130°C according to the compounding ratios shown in Table 1, and rolled kneaded. Using a 40TrL/m extruder (L/D=25).

A thickness of 1.0 mm is placed on a copper wire with an outer diameter of 2.0 m. A crosslinked insulated wire was produced by extrusion coating Os++ and then holding in a steam atmosphere of 13 Nff/cffl for 3 minutes.

The surface of this insulated wire was coated with a protective layer shown in Table 1 to a thickness of 10 μm, and cured using an ultraviolet spot @ (80 W/solder).

The evaluation results for each individual are as shown in the lower column of Table 1.

The evaluation was performed as follows.

Flame retardancy: A 300m long electric wire held horizontally is burned in a Bunsen burner with an oxidizing flame of about 130m, and after the Bunsen burner is removed, the flame will naturally go out, passing the test. If the wire does not self-extinguish, it will fail. be.

Surface condition (whitening) using a two-needle abrasion tester, MIL
The surface of the wire was rubbed under a load of 5003 in accordance with the standard W-22759D to examine whether it would whiten.

As is clear from Table 1, in Examples 1 to 6 according to the present invention, no whitening was observed and the flame retardance was good.

On the other hand, the surfaces of Comparative Examples 1 and 2 without a protective layer were considerably whitened in the needle abrasion test, and Comparative Example 3, in which the protective layer was not hardened, also whitened.

[Effects of the Invention] As explained above, the present invention provides a protective layer formed by curing a composition mainly composed of curable polybutadiene, and can prevent whitening due to mechanical stress such as bending or scratching. Moreover, it becomes possible to obtain a flame-retardant insulated wire that is flame-retardant and does not generate toxic halogen gas when burned.

Claims (1)

[Claims] (1) A protective layer made by curing a composition mainly composed of curable polybutadiene is provided on an insulator or sheath made of a flame-retardant electrical insulation composition made by mixing polyolefin with an inorganic flame retardant. Characteristic flame-retardant insulated wire.