JPH07211154A - Fire retardant cable - Google Patents

Abstract

PURPOSE:To prevent outflow of inclusions in an insulating material in the event of a fire and preclude the fire from spreading by forming a fire spread preventing wall from polyolefin resin in which hydrate inorganic substance is included at a certain specified spacing, and furnishing such walls in gaps of twisting of a plurality of insulated conductors. CONSTITUTION:A plurality of insulated core wires 1 each prepared by applying an insulating material 3 onto a conductor 2, and in the gaps due to twisting, fire spread preventing walls 4 are provided at a spacing l1 of 200-1000mm over the longitudinal direction and for a length l2 of 50-1000mm. The walls 4 consist of a fire retardant compound prepared by including 50-300 parts hydrate inorganic substance such as aluminum hydroxide, magnesium hydroxide, etc., in 100 parts by wt. polyolefin resin. On the outsides of each core wire 1, a sheath 5 is put made of polyethylene, etc., to which a fire retardant agent such as magnesium hydroxide is added, and thereby an intended fire retardant cable is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant cable for preventing outflow and spread of an insulator inclusion in a cable at the time of fire.

[0002]

2. Description of the Related Art Conventional flame-retardant cables have been generally designed to prevent the spread of flame by incorporating a flame-retardant agent in inclusions, holding tapes, and cable sheaths in terms of cost.

[0003]

The conventional fire spread prevention structure is effective for single-core cables and multi-core thick cables, but not so effective for multi-core thin cables.
This is because even if the sheath of a multi-fiber cable is not spread,
Insulators and inclusions act as fuses and spread the fire. On the other hand, in the multi-core thick cable, this can be prevented by the heat capacity of the sheath, but in the multi-fiber cable, the heat capacity of the sheath is small and it is difficult to prevent. There is also a method in which a flame retardant is mixed in all of the sheath, the inclusions, and the insulator, but there is a problem that the cable cost becomes high and it is not practical.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a flame-retardant cable capable of preventing the spread of fire even in a multi-core thin cable, which is characterized by a plurality of insulating wires. A flame spread prevention wall with a length of 50 to 1000 mm is provided at intervals of 200 to 1000 mm in the longitudinal direction of the cable in the gap portion where the cores are twisted, and the spread flame prevention wall is made of a polyolefin resin.
It is because 50 to 300 parts by weight of hydrated inorganic substances such as aluminum hydroxide and magnesium hydroxide are contained with respect to 100 parts by weight.

[0005]

1 is an explanatory view of a concrete example of a flame-retardant cable of the present invention. FIG. 1 (a) is a perspective view and FIG. 1 (b) is FIG. 1 (a).
FIG. In the drawing, reference numeral 1 is an insulated wire core in which an insulator 3 such as polyethylene is applied on a conductor 2, and a flame spread prevention wall 4 is provided in a gap portion formed by twisting a plurality of these insulated wire cores 1 at a predetermined interval l _1. Is provided with a predetermined length l _{2 and is} provided on the outside with a flame-retardant sheath 5 formed by adding a flame retardant such as magnesium hydroxide to polyethylene or the like.

The interval l ₁ between the fire spread prevention walls 4 is 200 to 1000 mm.
The length of the fire spread prevention wall 4 is 50 to 1000 mm. If the distance l ₁ is less than 200 mm, it is not much different from the case where a solid sheath is applied over the entire length of the cable, which leads to an increase in the material cost. ), And
If it is made larger than this, the meaning of the fire spread prevention wall is lost. If the length l ₂ of the fire spread prevention wall 4 is less than 50 mm, the effect of fire spread prevention is not sufficient, and if it exceeds 1000 mm, the meaning of the fire spread prevention wall becomes meaningless as in the above interval.

As the flame spread prevention wall, 50 parts of hydrated inorganic material is added to 100 parts by weight of polyolefin resin such as polyethylene.
A flame-retardant composition blended up to 300 parts by weight is used. Examples of the hydrated inorganic substances include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, barium hydroxide and the like. If the hydrated inorganic substance is less than 50 parts by weight, a sufficient effect of preventing the spread of fire cannot be obtained.
When it exceeds 00 parts by weight, the flexibility of the cable is impaired and the mechanical strength is lowered.

[0008]

[Experimental example] In order to demonstrate the performance of the flame-retardant cable of the present invention, the following sample was prepared and a flame-retardant test was conducted according to IEEE383. The results are shown in Table 1.

The product of the present invention: 100 parts by weight of polyethylene and 100 parts by weight of magnesium hydroxide are placed in a gap formed by twisting seven insulated wire cores obtained by extrusion-coating polyethylene to a thickness of 0.8 mm on a conductor having a cross-sectional area of 3.5 mm ^2. In a composition containing 1 part by weight, the length l ₂ =
A flame spread prevention wall having a length of 100 mm and an interval of l ₂ = 500 mm was formed, and a polyethylene sheath having the same composition was applied to the outside thereof to a thickness of 1.5 mm to form a cable.

Comparative Example 1: A conductor having a cross-sectional area of 100 mm ² was twisted with three insulation wire cores extruded and coated with polyethylene to a thickness of 2 mm, together with inclusions containing 100 parts by weight of a polyolefin resin and 50 parts by weight of an inorganic filler. Then, wind a 0.15 mm thick inorganic tape as a press-winding tape on it, and apply a polyethylene sheath of a composition in which 100 parts by weight of polyethylene is mixed with 100 parts by weight of magnesium hydroxide to a thickness of 2.2 mm to form a cable. Created.

COMPARATIVE EXAMPLE 2: Seven conductors having a cross-sectional area of 3.5 mm ² were extruded and coated with polyethylene to a thickness of 0.8 mm, and seven insulation cores
100 parts by weight of a polyolefin resin are twisted together with an inclusion containing 50 parts by weight of an inorganic filler, an inorganic holding tape is wound thereon, and a polyethylene sheath similar to that of Comparative Example 1 having a thickness of 1.5 mm is wound on the tape. It was applied to and the cable was created.

COMPARATIVE EXAMPLE 3 ^On a conductor having a cross-sectional area of 3.5 mm ² , polyethylene was extrusion-coated to a thickness of 0.8 mm on a single insulated wire core,
The same polyethylene sheath as in Comparative Example 1 was applied to a thickness of 1.5 mm to prepare a single-core cable.

[0013]

[Table 1]

As can be seen from the results in Table 1, Comparative Example 1
The multi-core thick cable and the single-core cable shown in 3 and 3 pass the standard even with the conventional structure, but the multi-core thin cable with the conventional structure of Comparative 2 does not pass the fully burned standard. On the other hand, it was confirmed that the multi-core fine cable of the present invention provided with the fire spread prevention wall passed the standard.

[0015]

As described above, according to the flame-retardant cable of the present invention, a fire spread prevention wall is provided in place of the inclusion that served as a squib in the event of a fire. It became possible to prevent the spread of fire. Therefore, it is effective to use it as a cable in places where disaster prevention is highly necessary, such as buildings and factories.

[Brief description of drawings]

FIG. 1 is an explanatory view of a specific example of a flame-retardant cable of the present invention,
FIG. 1A is a perspective view, and FIG. 1B is XX of FIG.
FIG.

[Explanation of symbols]

 1 Insulated wire core 2 Conductor 3 Insulator 4 Fire spread prevention wall 5 Sheath

Claims (1)

[Claims] 1. A gap formed by twisting a plurality of insulated wire cores,
50-1000 mm with a spacing of 200-1000 mm in the longitudinal direction of the cable
A fire spread prevention wall of length is provided, and the fire spread prevention wall is aluminum hydroxide based on 100 parts by weight of the polyolefin resin.
A flame-retardant cable characterized by containing 50 to 300 parts by weight of a hydrated inorganic substance such as magnesium hydroxide.