JPH0218434A - Flame-retardant electrically insulating composition - 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] [Field of Industrial Application] The present invention is applied to flame-retardant electrical insulation compositions that do not generate significant halogen-based gas when burned, particularly to insulation materials and sheath materials for N wires and cables. The present invention relates to a flame-retardant electrical insulation composition suitable for.

[Prior Art] Insulating materials and sheath materials for flame-retardant insulated wires and cables include methods of mixing halogen-containing compounds with ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, etc., chloroprene rubber, Polymers containing halogen elements, such as polyvinyl chloride, have been commonly used so far. However, these produce a lot of smoke when burned, causing problems such as corrosiveness to equipment and toxicity to the human body.In recent years, there has been a recent demand that these halogen-based gases not be emitted for safety reasons. This is becoming more and more common.

In light of this situation, a non-halogen flame-retardant insulating material with extremely low smoke and toxicity, which is made by mixing a large amount of metal hydroxide with ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer, has been inspected. It's starting to happen.

[Problems to be Solved by the Invention] However, in order to impart flame retardancy, it is necessary to add a large amount of metal hydroxide, and as a result, there has been a problem in that heat aging resistance is significantly reduced.

The present invention has been made based on the above, and aims to provide a flame-retardant electrical insulating composition that can impart desired flame retardancy, has excellent heat resistance, and does not generate toxic halogen gases. That is.

[Means and effects for solving the problems] The gist of the present invention is that 50 to 500 parts of metal hydroxide are added to 100 parts of 1-ethylene vinyl monoacetate copolymer or ethylene-acrylic acid ester copolymer. part, 0.5 parts by weight or more of acid weight lead, and 12 parts by weight or more of antioxidant O.

In the present invention, ethylene-vinyl acetate copolymer or ethylene-acrylic acid ester copolymer is used as the base polymer. Edylene-methyl acrylate copolymer, ■
Examples include dylene-edylacrylate copolymer, edylene-butyl acrylate copolymer, etc., and these can be used alone or in combination of two or more.

Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, and hydrotalcites. The extrusion processability of the composition can be improved by using those that have been surface-treated with a silane coupling agent, a titanate coupling agent, a fatty acid metal salt, or the like.

The metal hydroxide must be contained in an amount of 50 to 500 parts by weight per 100 parts by weight of the ethylene-vinyl acetate copolymer or ethylene-acrylic acid ester copolymer,
If it is less than 50 parts by weight, the desired flame retardancy cannot be imparted;
If the weight exceeds 0.00 weight, the workability will decrease and extrusion processing will not be possible.

It has been found that by adding zinc oxide to such a system, heat aging resistance is significantly improved, although the mechanism of action is not clear. It is necessary to add zinc oxide by 0.5i1''+ffiff, and if it is less than 0.5 parts by weight, the desired heat aging resistance cannot be imparted.

Antioxidants include amine, phenol, sulfur,
Examples include phosphorus compounds, and these may be used alone or in combination of two or more. By adding 0.2 parts by weight or more of the antioxidant, heat aging resistance can be greatly improved. Specific examples of antioxidants include phenyl-α-naphthylamine, 6-elhex-2,2,4-1-tmethyl-1,
2-dihydroquinoline, 2,6-tert-butyl-4-ethylphenol, 6-(4-hydroxy-3,5-di-tert-butyl-anilino)-2,4-suoctyrudio 1.3. 5-triazine, tetrakis-(methylene-3
-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate)methane, distearylthiodibrobionet, and the like.

In the present invention, in addition to the above components, crosslinking agents, lubricants, softeners, dispersants, etc. may be added as appropriate. Suitable cross-linking agents include dicumyl peroxide and Migiiso peroxide represented by 3-bis(t-butylperoxyisopropyl)benzene, and cross-linking lubricants such as sulfur, ethylene dimethacrylate, diacryl phthalate, p-quinone dioxime etc. may be used in combination. In addition, when crosslinking is done by electron beam irradiation,
It is common to add reactive monomers such as trimethylolpropane trimellitate and triallylisocyanurate as crosslinking aids.

[Example] Various ingredients were heated to 120°C according to the mixing ratios shown in the Example table.
After kneading, the 80 m/m extrusion 11 (L/
D=25) with a thickness of 2 on a copper conductor with an outer diameter of 9.0 mm.
．． Extrusion coating was performed to a thickness of 0 mm. After that 15N! F/cffl
Chemical crosslinking was carried out by holding the sample in a water vapor atmosphere for 3 minutes.

The evaluation results for each composition and wire are shown in the lower column of the table. The evaluation was based on the following.

Tensile properties: After drawing the insulated wire core and polishing it to one layer thickness, J
It was struck with a No. 3 I8 dumbbell and measured using a Schottsuba tensile tester at a tensile speed of 500 m/min.

Heat aging resistance: Pull out the insulated wire core, polish it to a thickness of 1 mm, and then punch it out with a JIS dumbbell No. 3. After that, it was heated at 150℃ for 96111J based on JR passenger company standards, and
After being left at 0°C for 24 hours, a tensile test was conducted.

Eleven flame-retardant double lines were lined up vertically and a flame-retardant test was conducted in accordance with IEEE standards, and those that burned completely were rejected.

As is clear from the table, Examples 1 to 7 according to the present invention show excellent results in terms of tensile properties, heat aging resistance, and flame retardance.

On the other hand, in Comparative Example 1, the miscibility m of the metal hydroxide is limited (
If it is less than ff, the flame retardance is rejected. Comparative Example 2.3 in which the amount of zinc oxide added was below the limit value and Comparative Example 4 in which no antioxidant was added had significantly poor heat aging resistance.

[Effects of the Invention] As explained above, according to the present invention, a flame-retardant electrical insulating composition that has excellent heat aging resistance and flame retardancy and does not generate toxic halogen gas when burned is obtained.

Claims (1)

[Claims] 1. 50 to 500 parts by weight of a metal hydroxide, 0.5 parts by weight or more of zinc oxide, and 100 parts by weight of an ethylene-vinyl acetate copolymer or an ethylene-acrylic acid ester copolymer. A flame-retardant electrical insulating composition containing 0.2 parts by weight or more of an inhibitor.