JPH01115944A - Flame-retardant electrically insulating composition - Google Patents

Abstract

PURPOSE:To obtain the above composition having excellent flame retardance, free from generation of toxic halogen-containing gas in combustion and suitable as an insulation material and sheath for cable, by compounding a polyolefin with specific amounts of an inorganic metal hydroxide and silicone resin powder. CONSTITUTION:The objective composition is produced by compounding 100pts. wt. of a polyolefin (e.g., ethylene-propylene copolymer) with (A) >=50pts.wt. of an inorganic metal hydroxide (e.g., aluminum hydroxide) and (B) >=1pt.wt. of fine powder of silicone having particle diameter of <=10mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flame-retardant electrical insulating composition that does not generate halogen gas when burned, and is suitable as an insulator or sheath material for electric wires and cables.

[Conventional technology] In recent years, we have developed flame-retardant technologies that do not emit halogen-based gases that can affect the human body or cause corrosion of equipment, assuming that fires occur in high-rise buildings, power plants, various plants, etc. There has been a strong demand for insulated wires and cables. Furthermore, the flame retardance is determined by the Vertical Tray Burning Test (VTF) according to IEEE (Institute of Electrical and Electronics Engineers) Standard 383.
Those who pass T) are required.

In the past, the only cables that satisfied such strict flame retardant standards were materials made of polyolefin mixed with halogen flame retardants, vinyl, and chloroprene rubber.

[Problems to be solved by the invention] However, there is a problem that electric wires and cables using these materials generate a large amount of halogen gas when burned, and the amount of smoke generated is large, hindering evacuation and firefighting activities. It was causing harm.

The present invention was made in view of the above circumstances, and its purpose is to have a high degree of flame retardancy that passes VTFT, generate less smoke when burned, and generate toxic halogen gas. The object of the present invention is to provide a flame-retardant electrical insulating composition that is free from flame retardants.

[Means for Solving the Problems] The gist of the present invention is to contain at least 50 parts by weight of an inorganic metal hydroxide and at least 1 part by weight of fine silicone resin powder per 100 parts by weight of polyolefin. .

In the present invention, examples of the polyolefin include ethylene propylene copolymer, ethylene propylene terpolymer, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, ethylene butene copolymer, and ethylene butene terpolymer. They can be used alone or in a mixture of two or more.

Examples of inorganic metal hydroxides include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, and hydrotalcites. In addition, the amount of inorganic metal hydroxide is 5 parts by weight per 100 parts by weight of polyolefin.
It is necessary to mix 0 parts by weight or more, and if it is outside this range, the desired flame retardance cannot be imparted.

The silicone resin fine powder is preferably one having a particle size of 10 μm or less, which causes less deterioration in mechanical properties. In addition, the amount of silicone resin fine powder is 50 parts by weight per 100 parts by weight of polyolefin.
It is necessary to mix at least a part by weight; outside this range, an effective carbonized layer will not be formed during combustion.

In the present invention, the molded product of the above composition can be used either uncrosslinked or crosslinked. Examples of crosslinking methods include crosslinking using organic peroxides, crosslinking using electron beam irradiation, and silane graft water crosslinking.

In the crosslinking using an organic peroxide, organic peroxides such as dicumyl peroxide and 3-bis(t-butylperoxyisopropyl)benzene are suitable as the crosslinking agent.

Furthermore, in crosslinking by electron beam irradiation, a reactive monomer such as trimethylolpropane trimellitate or triallyl isocyanurate is generally added as a crosslinking aid.

Furthermore, in the present invention, in addition to the above components, antioxidants, lubricants, carbon black, etc. may be added.

[Function] A high degree of flame retardancy can be imparted by adding silicone resin fine powder in addition to the inorganic metal hydroxide.

[Example] Various components were blended according to the blending ratios (based on weight) shown in the table, and the mixture was put into a 6-inch roll maintained at 100°C to perform roll cross-wiring. 40m/held at 120℃ after crosstalk
M extruder was used to extrude coat three stranded ethylene propylene rubber insulated wire cores with an outer diameter of 3.0 mm to a thickness of 1.5 mm, and in Examples 4 and 5, 15 Kg/
It was held in a water vapor atmosphere of cm2 for 3 minutes and crosslinked to produce various cables.

The cable evaluation results obtained on each side are shown in the lower column of the table. Flame retardancy was evaluated by arranging eight 2m long cables vertically and exposing them to a 70.0OOBTU flame from below for 20 minutes. If the flame self-extinguished, it was considered a pass; if it did not self-extinguish and completely burned down, it was judged as a failure. .

As is clear from the evaluation results in the table, the cables using the materials shown in Examples 1 to 6 sufficiently passed the vertical tray combustion test.

On the other hand, Comparative Example 1 with a small amount of inorganic metal hydroxide, Comparative Example 2 with added polymer fine powder other than silicone resin fine powder, and Comparative Example 3 with added amount of silicone resin fine powder less than the limit value The flame retardancy was also rejected.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a flame-retardant electrical insulating composition that has a high degree of flame retardancy and does not generate toxic halogen gas when burned.

Claims (1)

[Claims] (1) A flame-retardant electrical insulation composition comprising 50 parts by weight or more of an inorganic metal hydroxide and 1 part by weight or more of a silicone resin fine powder per 100 parts by weight of a polyolefin.