JPH0748323B2 - Flame-retardant wire / cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention does not generate a toxic halogen-based gas upon combustion,
Moreover, the present invention relates to a flame-retardant electric wire / cable excellent in heat aging resistance.

[Prior Art] Polyolefins, which are widely used because of their excellent electrical insulation, have been flammable materials that have been conventionally used as insulators and sheaths for electric wires and cables. When a fire occurs, there are many cases where the fire spreads through the wiring system of the electric wire / cable, and there is an increasing demand for flame-retardant electric wires / cables. In particular, as a recent trend, the IEEE (Institute of Electrical and Electronics Engineers) standard 383
VTFT (Vertical Tray Combustion Test) has been required to have a high degree of flame retardancy, which is required to pass the combustion test of multi-strip installation simulating the actual installation situation.

As a conventional insulating material for flame-retardant electric wires / cables, a method of mixing a halogen-containing compound with polyethylene or ethylene propylene rubber, or a polymer containing a halogen element represented by chlorinated polyethylene or polyvinyl chloride has been generally used. Has been used for.

However, the flame-retardant electrical insulating composition containing the halogen element generates a large amount of non-flammable halogen-based gas or the like at the time of fire, thereby attempting to block oxygen around the electric wire / cable to prevent combustion. Although it exhibits sufficient flame retardant properties, the halogen-based gas, etc. generated at that time is often toxic, such as hydrogen chloride, and causes a large amount of smoke containing such toxic gas. There is also a risk of a secondary disaster due to poor visibility, hindering evacuation behavior and fire extinguishing activities in the event of a fire, or the poisonous gas adversely affecting the human body.

Therefore, in place of the halogen-based compound, a non-halogen flame-retardant electrical insulating composition in which a metal hydroxide such as aluminum hydroxide or magnesium hydroxide is mixed as a flame retardant in polyolefin to emphasize the safety in the case of fire is provided. Proposed and attracting attention.

[Problems to be Solved by the Invention] The flame-retardant composition in which the above metal hydroxide is mixed utilizes the endothermic action when the hydroxide releases crystal water during a fire as a flame-retardant effect. Very little smoke, toxicity or corrosiveness.

However, since the above flame retardant has a small flame retarding effect, a drip phenomenon of melting and dropping at the time of combustion is observed and it is difficult to impart a high degree of flame retardance, simply by mixing it with a polymer.

In order to impart a high degree of flame retardance, it is necessary to add a large amount of metal hydroxide, and as a result, there has been a problem that the heat aging resistance is significantly lowered.

The object of the present invention is to solve the problems of the prior art as described above, to exhibit a high degree of flame retardancy without generating toxic halogen-based gas, and to greatly improve and improve heat aging resistance. It is intended to provide flame-retardant electric wires / cables.

[Means for Solving the Problems] The present invention is based on 100 parts by weight of polyolefin, 50 to 200 parts by weight of metal hydroxide, 0.5 parts by weight or more of silicone raw rubber,
Further, a composition containing 1 to 10 parts by weight of a hydroxybenzoyl isocyanurate compound and 1 to 10 parts by weight of a sulfur-containing ester compound is coated and crosslinked.

Examples of the polyolefin in the present invention include ethylene propylene polymer, ethylene propylene diene terpolymer, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene butene copolymer, and these are used alone or in combination of two or more kinds. To be done.

Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide and calcium hydroxide, and these may be surface-treated with a fatty acid, a fatty acid metal salt, a silane coupling agent, a titanate coupling agent or the like. desirable.

Metal hydroxide is 50 to 2 per 100 parts by weight of polyolefin
It is necessary to contain it in the range of 00 parts by weight, and if it is less than 50 parts by weight, the desired flame retardancy cannot be imparted, and if it exceeds 200 parts by weight, the heat aging resistance is significantly lowered.

The present invention adds silicone raw rubber to such a system,
It was further discovered that the addition of a hydroxybenzoyl isocyanurate compound and a sulfur-containing ester compound markedly improves the heat aging resistance.

It is necessary to add 0.5 part by weight or more of silicone raw rubber, and if less than 0.5 part by weight, the desired heat aging resistance cannot be imparted. Examples of the silicone raw rubber include dimethyl silicone raw rubber, methylphenyl silicone raw rubber, methyl vinyl silicone raw rubber, and methylphenyl vinyl silicone raw rubber.

The hydroxybenzoyl isocyanurate compounds, 1,3,5-tris (3 ^- 5 ^- - di -t- butyl-4-hydroxybenzoyl) include isocyanurate, and as the sulfur-containing ester compound di - Examples include lauryl-thio-di-propionate, di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis- (3-lauryl-thio-propionate) and the like. It is necessary to add these in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyolefin. If the amount is less than 1 part by weight, the desired heat aging resistance cannot be imparted, and if the amount exceeds 10 parts by weight, crosslinking inhibition becomes large. It becomes difficult to obtain sufficient physical properties.

In the present invention, it is necessary to crosslink the above components with an organic peroxide, electron beam irradiation or the like, but the purpose is to prevent thermal deformation at high temperature.

[Examples] Hereinafter, the present invention will be described with reference to Examples.

After mixing various components so as to have a mixing ratio as in Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1, the mixture was put into a 6-inch roll held at 120 ° C. to perform roll kneading, and after kneading Using an 80m / m extruder (L / D = 25) kept at 120 ° C,
A copper tape having an outer diameter of 1.8 mm was wrapped with a 20 μm-thick paper tape in a 1/2 wrap, and a 1.2 mm-thick extrusion coating was applied thereon. Then 1
Chemical cross-linking was carried out by holding in a steam atmosphere of 5 kg / cm ² for 3 minutes.

The evaluation results of the respective compositions and electric wires are shown in the lower column of the table. The evaluation was based on the following.

Tensile properties: The insulated core was pulled out and measured with a Shopper type tensile tester at a pulling speed of 500 mm / 2 minutes.

Thermal aging resistance: Insulated wire cores were pulled out and heated at 158 ° C for 7 days according to UL standard sub.758, and then left standing at 22 ° C for 24 hours to perform a tensile test.

Flame retardance: In accordance with JIS C3005, a horizontal test was conducted, and those that extinguished within 60 seconds were passed, and those that exceeded 60 seconds were rejected.

As is clear from Table 1, Examples 1 to 6 according to the present invention
Contains a metal hydroxide in the range specified by the present invention, and further contains a silicone raw rubber and a hydroxybenzoyl isocyanurate compound and a sulfur-containing ester compound in an appropriate range specified by the present invention. Good results are shown in both aging and flame retardancy.

On the other hand, in Comparative Example 1, the admixture amount of the metal hydroxide was less than the specified value of the present invention, and the flame retardancy was unacceptable. It can be seen that Comparative Example 2 in which the amount of the metal hydroxide added exceeds the specified value, Comparative Example 3 in which the silicone raw rubber is not added, or Comparative Example 4 in which the hydroxybenzoyl isocyanurate compound is not added is significantly inferior in heat aging resistance.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a flame-retardant electric wire / cable that is excellent in heat aging resistance and flame retardancy and does not generate a toxic halogen-based gas during combustion. Therefore, the significance of being able to open the conventional bottleneck is significant.

Claims (1)

[Claims] 1. To 100 parts by weight of polyolefin, 50 to 200 parts by weight of metal hydroxide, 0.5 parts by weight or more of silicone raw rubber, 1 to 10 parts by weight of hydroxybenzoyl isocyanurate compound and 1 to 10 of sulfur-containing ester compound.
A flame-retardant wire or cable formed by coating a composition containing parts by weight and crosslinking the composition.