JPH0363581B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a flame-retardant electrical insulating composition that can realize electric wires, cables, etc. that do not generate halogen gas when flame-retardant. [Prior Art] As a recent trend, there has been a strong demand for a high degree of flame retardancy for electric wires and cables for nuclear power plants, electric wires for vehicles, and electric wires for wiring inside panels and inside machines. Methods of imparting flame retardance have been to add halogen-containing compounds or phosphorus-containing compounds to polymers, or to use halogen-containing polymers, but these methods emit a large amount of smoke in the event of a fire; It is also considered a problem because it generates gases that are harmful to the human body. In light of this situation, a method of incorporating inorganic flame retardants such as aluminum hydroxide, which has very low smoke generation and toxicity, has been attracting attention. [Problems to be solved by the invention] However, if an inorganic flame retardant is simply mixed into polyethylene or ethylene vinyl acetate copolymer, a drip phenomenon in which burning materials fall during combustion is observed, and the UL standard VW-1 It has been difficult to impart flame retardancy of this level. The present invention has been made based on the above,
It is possible to obtain a molded article that does not produce drips during combustion, has a high degree of flame retardancy, and does not generate toxic halogen gas during combustion. The object of the present invention is to provide a flame-retardant electrical insulation composition. [Means for Solving the Problems] The flame retardant composition of the present invention has a polyethylene or ethylene vinyl acetate copolymer and an ethylene ethyl acrylate copolymer.
It is characterized by containing 50 to 300 parts by weight of an inorganic flame retardant. In the present invention, the polyethylene may be any of commercially available low density, medium density, and high density polyethylene. Further, as the ethylene vinyl acetate copolymer, one having a melt index of 20 or less is preferable. Inorganic flame retardants include aluminum hydroxide,
Basic magnesium carbonate, magnesium hydroxide,
Examples include hydrotalcite. Such inorganic flame retardants may be added in an amount of 50 parts by weight per 100 parts by weight of a blend of polyethylene or ethylene vinyl acetate copolymer and ethylene ethyl acrylate copolymer.
It is necessary to mix it in the range of ~300 parts by weight,
If the amount is less than 50 parts by weight, the desired flame retardancy cannot be imparted, and if it exceeds 300 parts by weight, the melt viscosity of the compound becomes extremely high, making extrusion molding impossible. In the present invention, in addition to the above components, a crosslinking agent,
Antioxidants, lubricants, softeners, dispersants, etc. can be added as appropriate. As a crosslinking agent, dicumyl peroxide, 3
Organic peroxides typified by bis(t-butylperoxyisopropylbenzene) are suitable. Examples of antioxidants include amine antioxidants such as phenyl-α-naphthylamine, N,N'-di-β-naphthyl-p-phenylenediamine, and N-isopropyl-N'-phenyl-p-phenylenediamine. , 2,6-di-t-butyl-4-methylphenol, hindered phenol, 6-(4-hydroxy-3,5-di-tert-butyl anilino)
-2,4-bis-octyl-thio-1,3,5-
Triazine, 4,4'-methylene-bis-(2,6
Examples include phenolic antioxidants such as -di-tert-butylphenol). [Example] Various ingredients were put into a 6-inch roll maintained at 120°C in the proportions shown in Table 1, and rolled kneaded.
Using a 40m/m extruder (L/D=25), outer diameter 3.0
It was extrusion coated to a thickness of 1.0 mm onto a 1.0 mm copper conductor and subsequently crosslinked by holding in water vapor at 13 Kg/cm ² for 3 minutes. The evaluation results of the cable thus produced are as shown in the lower column of Table 1. In the flame retardancy evaluation, if the electric wire kept vertically burns in a burner, it will pass if it disappears within 1 minute, and if it burns for more than 1 minute, it will fail. Also, if it drips and burns to the underlying cotton, it will not pass the test.

【table】

[Table] As is clear from Table 1, all of Examples 1 to 6 according to the present invention show no drips during combustion, pass UL standard VW-1, and have good extrusion processability. . On the other hand, in Comparative Example 1, the amount of inorganic flame retardant added was less than 50 parts by weight, causing dripping and UL
It fails the standard VW-1. In Comparative Example 2, the amount of inorganic flame retardant was 300 parts by weight or more, and the melt viscosity increased significantly, making extrusion impossible. In Comparative Example 3, since the ethylene vinyl acetate copolymer was used alone, dripping occurred and it failed the UL standard VW-1. [Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a molded article that does not produce drips during combustion, has high combustibility, and does not generate toxic halogen gas during combustion. .

Claims (1)

[Claims] 1 Flame retardant characterized by containing 50 to 300 parts by weight of an inorganic flame retardant per 100 parts by weight of a blend of 80 to 50 weight % polyethylene or ethylene vinyl acetate copolymer and 20 to 50 weight % ethylene ethyl acrylate copolymer Electrical insulation composition.