JPH0781039B2 - Flame-retardant wire / cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention does not generate harmful halogen-based gas upon combustion,
Moreover, the present invention relates to a flame-retardant electric wire / cable including an insulator or a sheath having hardness flame retardancy.

[Prior Art] Polyolefins used as insulators and sheaths for electric wires and cables are flammable, and in the event of a fire, there are many cases where the fire spreads through the electric wires and cables.・ The demand for flame-retardant cables has suddenly increased.

Recently, high flame retardancy has been demanded mainly in electric wires and cables, and the vertical combustion test of ULVW-1 and
There has been a growing demand for the realization of highly flame-retardant electric wires and cables that pass the vertical tray combustion test levels such as IEEE standard 383 and IEC standard 332.

As a method of making a polyolefin flame-retardant, a method of mixing a halogen-containing compound or the like has been generally adopted.
Such a flame-retardant material generates a large amount of non-twisting halogen-based gas, etc. in the event of a fire, thereby shutting off oxygen in the surroundings of electric wires and cables and preventing combustion. Although it exhibits flammability characteristics, the halogen-based gas, etc. that is generated at that time is often toxic, such as hydrogen chloride, and a large amount of smoke containing such toxic gas causes poor visibility, causing a fire. There is also a risk of secondary disasters such as hindering evacuation behavior and fire extinguishing activities in the event of a fire, or adverse effects on the human body due to the poisonous gas. There is also a risk of corroding the equipment.

Therefore, instead of the above halogen-based compounds, a flame-retardant material has been proposed in which a metal hydroxide such as magnesium hydroxide is mixed and the safety in case of fire is emphasized. It has been applied and is attracting attention.

[Problems to be Solved by the Invention] The flame-retardant material mixed with the metal hydroxide utilizes the endothermic action when the hydroxide releases crystal water during a fire as a flame-retardant effect. Very low in toxicity, toxicity or corrosivity.

However, since the metal hydroxide has a small flame retardant effect,
In order to impart a high degree of flame retardancy as described above, it is necessary to add a large amount of metal hydroxide, and as a result, mechanical properties such as tensile properties of the insulator and the sheath are significantly reduced. There is a problem.

The object of the present invention is to solve the problems of the prior art as described above, toxic does not generate a halogen-based gas, has a high degree of flame retardance that passes the vertical combustion test level, and is excellent. An object of the present invention is to provide an electric wire / cable provided with an insulator or a sheath having mechanical characteristics.

[Means for Solving the Problems] The electric wire / cable of the present invention is prepared by mixing 100 to 300 parts by weight of a mixture of magnesium hydroxide and calcium aluminate with 100 parts by weight of a polyolefin to obtain the magnesium hydroxide and the calcium aluminate. The ratio is 90/10 to 5 by weight
An insulating material or a sheath is formed of a flame-retardant electrical insulating composition having a composition of 0/50.

By using magnesium hydroxide and calcium aluminate as a flame retardant in combination so that the weight ratio is 90/10 to 50/50, it has been found that the flame retardancy can be significantly improved and the present invention has been achieved. Is.

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

In the present invention, magnesium hydroxide is used as a metal hydroxide from the viewpoint of high flame retardancy, but as this magnesium hydroxide, the average particle diameter is 0.1 to 10 due to aggregation, toughness, flame retardancy, water resistance and the like. It is preferable to use those having a surface treatment of 5 μm with a fatty acid metal salt, a silane coupling agent, a titanate coupling agent, or the like.

The calcium aluminate used in combination with this is 3CaO ・ Al ₂ O ₃
-A compound represented by 6H ₂ O, which greatly improves flame retardancy when used in combination with magnesium hydroxide. Calcium aluminate should have surface treatment with fatty acid, fatty acid metal salt, silane coupling agent, titanate coupling agent, etc. with an average particle size of 0.1-5 μm due to aggregation, toughness, flame resistance, water resistance, and processability. Is preferred.

The total admixture of magnesium hydroxide and calcium aluminate must be in the range of 100 to 300 parts by weight with respect to 100 parts by weight of polyolefin.
The weight ratio of calcium aluminate must be 90/10 to 50/50. If the total amount of admixture is less than the specified value, the desired flame retardancy cannot be imparted, and if it exceeds the specified value, the workability and toughness are significantly impaired. Regarding the admixture ratio, when the amount of magnesium hydroxide exceeds or falls below the specified value, the synergistic effect on flame retardancy is hardly seen.

By subjecting at least one of magnesium hydroxide and calcium aluminate to a surface treatment with a silane coupling agent, it becomes possible to suppress a decrease in insulation resistance after water immersion.

Examples of silane coupling agents include unsaturated silanes, ethoxysilanes, mercaptosilanes and aminosilanes.
Specific examples include vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

In the present invention, in addition to the above components, a crosslinking agent, an antioxidant, a lubricant, a dispersant, a coloring agent and the like may be added as appropriate.

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

Various components were kneaded using a 12-inch roll according to the formulations shown in the columns of Examples 1 to 10 in Table 1 and Comparative Examples 1 to 5 in Table 2, and then a 40 m / m extruder (L / D = 22), a conductor with a core wire outer diameter of 1.8 mmφ and a 10 μm paper separator is vertically attached while extrusion-coated to a thickness of 1.8 mm, and then crosslinked by holding in a steam atmosphere of 15 kg / cm ² for 3 minutes. did.

The tensile properties and flame retardancy (vertical combustion test) of the insulated wire thus manufactured were evaluated, and the results were
The results are shown in the lower column of Table and Table 2.

Each evaluation method is as follows.

Tensile properties: JIS C30 for samples excluding core wire and separator
In accordance with 05, the tensile speed was measured at 500 mm / min.

Flame retardance (vertical combustion test): It was performed according to UL44. That is, the sample is placed vertically, a burner flame is applied to the lower part of the test for 15 seconds, and the burning time after removing the burner flame is measured. This was repeated 5 times, and the burning time was 60 seconds or less in each case, and the case where the flag of the kraft paper attached to the upper part of the sample and the cotton laid on the lower part of the sample were not burned was judged to be acceptable. If the burning time exceeds 60 seconds, or if the flag or cotton burns, it was judged as a failure.

As is clear from Tables 1 and 2, Examples 1 to 10 according to the present invention all have excellent tensile properties and flame retardancy passes the vertical combustion test. Comparative Examples 1 and 2 are cases in which the total admixture of magnesium hydroxide and calcium aluminate deviates from the specified values of the present invention, and the flame retardancy and tensile properties are insufficient. Comparative Example 3 is one in which only magnesium hydroxide is added, and Comparative Example 5 is one in which only calcium aluminate is added, and fails the vertical combustion test. In Comparative Example 5, the content ratio of magnesium hydroxide and calcium aluminate deviates from the specified value of the present invention, and fails the vertical combustion test.

Table 3 shows the results of measuring the insulation resistance of Examples 1 to 3. The insulation resistance was measured by immersing 900 mm excluding the end of the electric wire of 1000 mm in water at 20 ° C. and measuring it with an insulation resistance meter after 5 minutes (initial). Next, immerse this in 75 ° C water, 60Hz,
Immersion electricity was applied for 15 days under the condition of 600V, and then measured with an insulation resistance meter at 75 ° C (15 days after immersion of electricity).

In Examples 2, 3, 5, 6, 8, and 10 in which at least one of magnesium hydroxide and calcium aluminate is surface-treated with a silane coupling agent, there is some insulation resistance even after 15 days of water immersion and application of electricity. . This allows
A flame-retardant insulated wire with excellent water resistance can be realized.

[Effects of the Invention] As described above, according to the present invention, no toxic halogen-based gas is generated during combustion, and it has a high degree of flame retardance that passes the vertical combustion test, and also in mechanical characteristics. Since it is possible to realize flame-retardant electric wires / cables that are fully satisfactory, the safety in case of fire can be improved and the industrial value is very large.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08K 3:22 3:24) (72) Inventor Norio Takahata 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Electric Cable Research Institute (72) Inventor Tokuji Tsunezumi 1 at 4025 Miho, Shimizu City, Shizuoka Prefecture, Japan Shimizu Plant, Nippon Light Metal Co., Ltd. (72) Inventor Susumu Watanabe 1 at 4025 Miho, Shimizu City, Japan Shimizu Plant, Kinka Co., Ltd. (56) Reference JP-A-63-39939 (JP, A)

Claims (2)

[Claims] 1. A mixture 100 comprising magnesium hydroxide and calcium aluminate per 100 parts by weight of polyolefin.
~ 300 parts by weight are mixed to form an insulator or sheath with a flame-retardant electrical insulating composition that is configured so that the weight ratio of magnesium hydroxide to calcium aluminate is 90/10 to 50/50. Flame-retardant wire / cable characterized by being formed. 2. The flame-retardant wire / cable according to claim 1, wherein at least one of the magnesium hydroxide and calcium aluminate is surface-treated with a silane coupling agent.