JPH03247639A - Fire retardant electric insulation composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition having excellent fire retardance without deteriorating mechanical properties nor generating toxic gas in burning by mixing polyolefin with a mixture comprising magnesium hydroxide and aluminum hydroxide having a specific particle diameter. CONSTITUTION:(A) 100 pts.wt. polyolefin is mixed with 100-300 pts.wt. mixture composed of (B) magnesium hydroxide, preferably having 0.1-5mum average particle diameter and surface treated with fatty acid (metallic salt), silane coupling agent or titanate coupling agent, etc., and (C) aluminum hydroxide having >=0.5mum average particle diameter, preferably surface treated with the same method as the component B in a weight ratio of B/C=90/10-50/50 to afford the aimed composition suitable for insulating material of electric wire or cable having excellent fire resistance and mechanical properties without generating toxic halogen-based gas in burning.

Description

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

[Conventional technology] Materials traditionally used as insulators and sheaths for electric wires and cables, including polyolefin, which is widely used due to its excellent electrical insulation properties, are all flammable and can cause fires. When a fire occurs, there are many cases in which the fire spreads through the wiring system of electric wires and cables, and the demand for flame-retardant electric wires and cables has suddenly increased.

Recently, flame retardant requirements have become more sophisticated, especially for electric wires and cables, and there is a demand for highly flammable materials that meet the ULVW-1 vertical combustion test and vertical tray combustion tests such as IEBE Standard 383 and IEC Standard 332. It's starting to look like this.

As a method for making polyolefins flame retardant, a method of mixing a halogen-containing compound or the like has generally been adopted.

However, such flame-retardant electrical insulation compositions generate a large amount of nonflammable halogen-based gas in the event of a fire, thereby blocking oxygen around electric wires and cables and preventing combustion. Although it exhibits sufficient combustion properties, many of the halogen gases generated are toxic, such as hydrogen chloride, and the visibility is poor because a large amount of smoke containing such toxic gases is generated. This may impede evacuation actions and firefighting efforts in the event of a fire, or there is a risk of secondary disasters such as the toxic gas having an adverse effect on the human body.Furthermore, the halogen gas may interact with moisture in the air There is also a risk that it will react with hydrohalic acid and corrode equipment.

Therefore, instead of the halogen compounds mentioned above, an inorganic flame retardant such as aluminum hydroxide or magnesium hydroxide was mixed in, and a highly flame-retardant electrical insulating composition was proposed, emphasizing the safety in the event of a fire. There are many people who collect.

[Problems to be Solved by the Invention] The flame retardant composition containing the above-mentioned inorganic flame retardant utilizes, as a flame retardant effect, the thermal effect when the hydroxide releases water of crystallization in the event of a fire. It has very little smoke, toxicity, or corrosivity.

However, inorganic retardants have a small retardant effect, so
In order to provide a high degree of flame retardancy that meets the above combustion tests, it is necessary to add a large amount of inorganic flame retardant.
As a result, there is a problem in that the mechanical properties such as the tensile properties of the resulting insulator or sheath are significantly reduced.

The purpose of the present invention is to solve the problems of the prior art as described above, and to achieve high flame retardancy that passes the vertical tray combustion test level by incorporating an inorganic flame retardant that does not generate harmful halogen gases. At the same time, it is an object of the present invention to provide a flame-retardant electrical insulating composition that can sufficiently maintain its mechanical properties.

[Means for Solving the Problems] The present invention provides 100 to 300 parts of a mixture of magnesium hydroxide and aluminum hydroxide having an average particle size of 0.5 μm or less per 100 parts by weight of polyolefin. Mix the amount of
In this case, the ratio of magnesium hydroxide/aluminum hydroxide is 90/10 to 50,150 by weight.

In the present invention, polyolefins include ethylene propylene rubber, polyethylene, ethylene butene copolymer,
Examples include ethylene butene terpolymer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, and ethylene methyl methacrylate copolymer, and these can be used alone or in combination of two or more.

Magnesium hydroxide has agglomeration, toughness, flame retardancy, water resistance,
From the viewpoint of processability, it is preferable to use particles having an average particle size of 0.1 to 5 μm and surface-treated with a fatty acid, a fatty acid metal salt, a silane coupling agent, a titanate coupling agent, or the like.

It was discovered that flame retardancy can be greatly improved by using this together with aluminum hydroxide having an average particle size of 1 μm or less, leading to the present invention. The average particle size of aluminum hydroxide is 0.
5 μm or less is preferable, and 0.5 μm or less provides a remarkable combined effect, and from the viewpoint of agglomeration, toughness, flame retardancy, water resistance, processability, etc., fatty acids, fatty acid metal salts, silane coupling agents, titanate coupling agents are used. It is preferable to perform a surface treatment with, etc.

The total amount of magnesium hydroxide and aluminum hydroxide must be mixed in a range of 100 to 300 parts by weight per 100 parts by weight of polyolefin, and the ratio of magnesium hydroxide/aluminum hydroxide is 90/1 by weight.
It needs to be between 0 and 50150. If the total mixing amount is less than the limit value, the desired flame retardancy cannot be imparted, and if it exceeds the limit value, workability and toughness will be significantly impaired, and regarding the mixing ratio, the ratio of metal hydroxide is limited. If the value exceeds the limit value or is less than the limit value, almost no synergistic effect on flame retardancy will be observed.

In the present invention, in addition to the above components, a crosslinking agent, an antioxidant, a lubricant, a dispersant, a coloring agent, etc. may be added as appropriate.Example] The present invention will be described below with reference to Examples.

The various ingredients were kneaded using a 12-inch roll according to the formulations shown in the columns of Examples 1 to 5 and Comparative Examples 1 to 4 in Table 1, and then using a 40 m/m extruder (L/D = 22). A conductor having a core wire outer diameter of 1.8φ was coated by extrusion to a thickness of 1.8 mm while a 10 μm paper separator was attached vertically. Items that require crosslinking are then cross-linked with 15 kg/CI+” water vapor.
Crosslinked for minutes.

Each evaluation method is as follows.

Tensile properties: JI sample excluding core wire and separator
Measured according to SC3005 at a tensile rate of 500 sam/l1in.

Vertical combustion test: Conducted in accordance with UL44, those with a combustion time of 60 seconds or less were judged to pass, and those with a burning time of over 60 seconds were judged to fail.

The respective evaluation results are shown in the lower column of Table 1.

As is clear from Table 1, Examples 1 to 5 according to the present invention
Both have excellent tensile properties and flame retardancy at a level that passes a vertical combustion test.

On the other hand, in Comparative Example 1.2, the total mixing amount of magnesium hydroxide and aluminum hydroxide was outside the limited value, and the flammability and tensile properties were insufficient.

In Comparative Example 3, the ratio of magnesium hydroxide/aluminum hydroxide was outside the limited value, and it failed the vertical combustion test. Further, Comparative Example 4 in which the average particle size of aluminum hydroxide was outside the limited value failed the vertical combustion test.

[Effects of the Invention] As described above, the flame-retardant electrical insulation composition according to the present invention has excellent flame retardancy and does not generate halogen gas when burned, so it can improve safety in the event of a fire and , it has sufficiently satisfactory mechanical properties and is of great industrial value.

Claims (1)

[Claims] (1) 100 to 300 parts by weight of a mixture consisting of magnesium hydroxide and aluminum hydroxide with an average particle size of 0.5 μm or less is mixed with 100 parts by weight of polyolefin, and the ratio of magnesium hydroxide/aluminum hydroxide is adjusted by weight. A flame-retardant electrical insulating composition having a ratio of 90/10 to 50/50.