JPS6337145A - Flame-retardant electrical insulation composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition combustible without emitting toxic gas and further having high tensile strength and water-resistance, by compounding a polyolefin with aluminum hydroxide treated with a mercaptosilane. CONSTITUTION:100pts.wt. of a polyolefin is compounded with 50-500pts.wt. of aluminum hydroxide having an average particle diameter of <=0.2mum and surface-treated with a mercaptosilane such as mercaptoethyltrimethoxysilane, mercaptopropyltrimethoxysilane, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a flame-retardant electrical insulation composition that does not generate toxic halogen gas when burned, and is particularly applicable to insulation materials and sheath materials for electric wires and cables. The present invention relates to a flame-retardant electrical insulation composition suitable for.

[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 halogen-containing compound, a phosphorus-containing compound, etc. has generally been adopted. However, these produce harmful smoke when burned, causing problems such as corrosiveness to equipment and toxicity to the human body. In particular, recently there has been a demand for not generating such halogen-based gases from the standpoint of safety.

In light of this situation, inorganic flame retardants with extremely low smoke generation and toxicity are attracting attention. Among them, aluminum hydroxide is the most typical inorganic flame retardant.

[Problems to be solved by the invention] However, in order to impart flame retardancy, it is necessary to add a large amount of aluminum hydroxide, which results in a decrease in the tensile properties and water resistance of the resulting insulator and sheath. There is a problem.

The present invention has been made based on the above, and an object of the present invention is to provide a flame-retardant electrical insulating composition that can impart flame retardancy, has excellent tensile properties and water resistance, and does not generate toxic halogen gases. This is the purpose.

[Means for solving the problems] The flame-retardant electrical insulation composition of the present invention comprises polyolefin 10
50 to 50 parts by weight of aluminum hydroxide with an average particle size of 0.2 μm or less that has been surface-treated with mercaptosilane.
It is characterized by containing 0 parts by weight.

In the present invention, examples of the polyolefin include ethylene propylene copolymer, ethylene propylene dienter polymer, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene butene copolymer, and ethylene butene dieter polymer, which may be used alone or in combination. It is possible to use more than one species in combination.

In the present invention, aluminum hydroxide is used as a flame retardant mixed into the polyolefin, and H8 (CH2) is used to improve the dispersibility and water resistance in the polyolefin. 5
It is necessary to use one surface-treated with a mercaptosilane represented by i(OR)3 [n: an integer of 1 to 10, R: an alkyl group]. Specific examples of mercaptosilane include mercaptoethyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, and the like. It is necessary to use aluminum hydroxide whose surface is treated with mercaptosilane and has an average particle size of 062 μm or less; anything larger than this is accompanied by a significant decrease in tensile properties. Although the lower limit is not particularly defined, it is generally 0.01 μm or more. The content of aluminum hydroxide must be in the range of 50 to 500 parts by weight per 100 parts by weight of polyolefin, and
If it is less than 500 parts by weight, the desired flame retardancy cannot be imparted.
If the amount exceeds 1 part by weight, the processability will be significantly reduced and extrusion molding will 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(t
-butylperoxyisopropyl)benzene is suitable, and as a crosslinking agent,
Sulfur, ethylene dimethacrylate, diallyl phthalate, p-quinone dioxime, etc. may be used in combination. Also,
In the case of crosslinking using ionizing radiation such as an electron beam, a reactive monomer such as trimethylolpropane trimellitate or triallyl isocyanurate is generally added as a crosslinking aid. Furthermore, it is also possible to graft or copolymerize a silicone compound typified by vinyltrimethoxysilane to a polyolefin and crosslink it in the presence of moisture. Examples of antioxidants include amine antioxidants such as phenyl-α-naphthylamine, N,N''-di-β-naphthyl-p-phenyl diamine, and 2゜6-dit.
Examples include phenolic antioxidants such as -butyl-4-methylphenol and hindered phenol.

〔Example〕

100% of various ingredients according to the formulation shown in Table 1.
The mixture was placed in a 6-inch roll kept at 120°C, and the rolls were mixed.
L/D-25) with a thickness of 1 on a copper wire with an outer diameter of 2.0
．． An insulated wire was produced by extrusion coating to a thickness of 0 mm (Example 5)
, 6). For Examples 1 to 4 and Comparative Examples 1 to 3, crosslinked insulated wires were produced by extrusion coating and then holding in a steam atmosphere of 13 kg/c for 3 minutes for crosslinking.

The evaluation results for the insulated wires produced on each side are shown in the lower column of Table 1.

The evaluation was based on the following.

After two-roll dispersion, a sheet with a thickness of 1 inch was taken out and observed under a microscope with a magnification of 20 times.

Flame retardancy: Based on JISC3004, if a wire held horizontally is burned in a burner and disappears within 1 minute, it is passed; if it burns for more than 1 minute, it is rejected.

Tensile properties: Pull out the copper wire from the wire, leave it in a constant temperature room at 20℃ for one day, and then use a Schopper type tensile tester at a tensile speed of 5.
Measured at 00 rAll/m1m.

Water resistance: Dry each sample at 80°C for 24 hours, then
The insulation resistance after being immersed in water at 5℃ for one month is D.
Evaluation was made by determining I.

As is clear from Table 1, Examples 1 to 1 according to the present invention
No. 6 all passed the flame retardant test, had good dispersibility, excellent tensile properties, and showed good insulation resistance even after being immersed for one month. On the other hand, in Comparative Example 1, in which the content of aluminum hydroxide was below the specified value, the flame retardance was rejected, and in Comparative Example 2, in which the content of aluminum hydroxide was above the specified value, extrudability was poor and molding was impossible. Also,
Comparative Example 3, in which the average particle size of aluminum hydroxide exceeds the specified value and is untreated, is inferior in dispersibility, tensile strength, and water resistance.

[Effects of the Invention] As explained above, the present invention uses aluminum hydroxide with an average particle size of 0.2 μm or less that has been surface-treated with mercaptosilane as a flame retardant, and has good tensile properties and water resistance. It is now possible to obtain an electrical insulator that can be imparted with flame retardancy without having to maintain its properties, and that does not generate toxic halogen-based gases when burned.

Claims (1)

[Claims] (1) A flame-retardant electrical insulation composition containing 50 to 500 parts by weight of aluminum hydroxide having an average particle size of 0.2 μm or less and surface-treated with mercaptosilane per 100 parts by weight of polyolefin.