JPH0326569Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a flame-retardant cable that reduces disasters by preventing insulators, intervening materials, and other constituent materials made of flammable and drip-prone materials from melting and flowing out in the event of a fire. be. In various cables, polyethylene, cross-linked polyethylene, etc. are used as conductor insulators, and in the case of multi-core cables, tapes such as polypropylene or polyester are used as intervening tapes.
Many use polyvinyl chloride as the sheath. For example, there are cables for power (EV, CV), control (CEV, CCV), and instrumentation (IPEV, IPCV). Conventionally, in this type of cable, the flame retardance of the entire cable is achieved by making the sheath material flame retardant. However, although these cables are made flame-retardant by making the sheath material, ie, polyvinyl chloride, etc. flame-retardant as mentioned above, the insulating material of polyethylene, cross-linked polyethylene, and the intervening tape material of polypropylene, polyester, etc. Because it is a flammable and drip-prone material, it melts, drips, and flows out when exposed to flames in the event of a fire. Once the sheath material is burnt and carbonized to expose the inside, the molten material flows onto the surface of the combustion residue of the sheath, gasifies and ignites, which further promotes combustion and makes it difficult to extinguish the fire. It was hot. In addition to the above-mentioned insulating materials and intervening tape materials, when flammable and drip-prone materials similar to those described above are used for other constituent materials, there is the same problem of accelerated combustion as described above. Ta. Therefore, in order to improve the flame retardancy of these cables, the flame retardance of the sheath material had to be considerably high. For example, the 0.1 value (oxygen index) had to be around 40-42. However, in order to increase the flame retardancy, it is necessary to use a compound that sacrifices some of its characteristics as a cable sheath, and also that highly flame retardant materials are generally expensive. There were also problems. The present invention was devised in view of such conventional problems. The purpose of this is to prevent the melting and leakage of insulators, intervening materials, and other constituent materials as much as possible, and to create a flame-retardant material that allows the use of sheath materials with reasonable flame retardancy, and even normal sheath materials. We provide sex cables. The feature of the present invention is that it uses insulators, intervening materials, and other constituent materials made of flammable and drip-prone materials such as polyethylene, crosslinked polyethylene, polypropylene, and polyester, and that the above-mentioned insulation is removed under heated conditions. In cables with a structure in which the body, intervening material, etc. melt and flow outward, carbonization of silk tape, etc., which is carbonized by heating, is placed on the insulator, etc. in single-core cables, and on the twisted wire core bundle in multi-core cables. A tape layer is applied airtightly on the inside, a non-combustible tape layer made of an inorganic material other than metal is airtightly formed on the outside, and on top of this, a non-highly flame-retardant material with moderate flame retardancy is applied. When a rubber or plastic sheath is applied and the sheath is destroyed in a fire and the non-flammable tape layer made of an inorganic material other than metal is exposed to flames, the tape underneath the non-flammable tape layer becomes carbonized. A carbonized layer is formed, and this and a nonflammable tape layer prevent the above-mentioned insulator, intervening material, etc. from melting and flowing outward. Note that non-highly flame retardant sheaths with moderate flame retardancy differ depending on the sheath material, but
For example, in the case of polyvinyl chloride, the OI value is less than 40,
This refers to cases exceeding 24, for example around 28. In this case, a carbonized tape layer that carbonizes when heated and a nonflammable tape layer made of an inorganic material other than metal,
Each layer may be constructed independently, or both layers of tape may be bonded together to form an integrated structure. As mentioned above, the tape made of a material that is carbonized by heating is a tape that is placed under the nonflammable tape layer made of an inorganic material other than metal, and is carbonized by the heat during heating due to a fire, etc., and remains in its original shape. In order to prevent the leakage of molten polyethylene, cross-linked polyethylene, polypropylene, polyester, etc. inside the cable, paper, especially kraft paper, carbon paper, etc., and cellulose-based materials such as human silk cloth are most suitable. It is. When using paper, in addition to regular smooth paper,
It may also be one with crepe processing. In particular, in the case of single-core cables that have been creped, they can be expected to act as a buffer layer to prevent the external nonflammable tape from breaking due to expansion of the insulator during heating. In addition, as tapes made of non-flammable materials made of inorganic materials other than metals, laminate tapes of asbestos fibers and polyester or polyethylene, or glass cloth tapes coated with silicone varnish, alkyd varnish, silicone rubber, etc. can be used. . The noncombustible tape can have a thickness of about 0.05 to 2.0 mm, but in consideration of workability when winding the tape, a thickness of 0.1 to 1.0 mm is appropriate. The reason why the tape made of the material that is carbonized by heating is carbonized during heating due to fire etc. is that the non-flammable tape layer applied on the tape cuts off the supply of air, resulting in a steam-baked state. The carbonized tape layer remains in its original shape and forms an effective leakage prevention layer for the molten material inside the cable, as described above. In addition, each tape is not only applied by wrapping,
It is also possible to apply it vertically. In that case, it is preferable to wrap glass yarn, glass cloth tape, asbestos tape, etc. in a gap or in layers to hold it down. Next, the present invention will be explained in more detail with reference to FIGS. 1 and 2. The illustrated cable is a multi-core cable. In the figure, a conductor 1 is coated with polyethylene, crosslinked polyethylene, etc. as an insulator 2 to form a wire core 3. Three of these wire cores 3 are twisted together to form a wire core bundle, and on the outside thereof, there is a carbonized tape layer 4 that is carbonized by heating, which is a feature of the present invention, and an airtight non-flammable tape layer made of an inorganic material other than metal. 5 is airtightly applied, and the nonflammable tape layer 5 is covered with a sheath 6 made of rubber, plastic, or the like. The tape for the tape layer 4 is made of kraft paper, human silk cloth, etc., and is wound in layers. And the wrap width of the wrap part 7 is 1/4 of the tape width.
To some extent. The tape for the nonflammable tape layer 5 applied on the carbonized tape layer 4 thus formed is a laminate tape of asbestos tape and plastic film, which are wound in layers. In this case, the wrap width of the wrap portion 8 is set to be 1 mm or more as described above. The sheath 6 coated on top of this does not need to have a flame retardancy as high as conventional ones, for example, 0.1
Polyvinyl chloride, polyethylene or chloroprene rubber having a flame retardant value of around 28, as well as ordinary polyvinyl chloride, flame-retardant polyethylene, etc. can be used. In the cable of the present invention, in addition to the above-mentioned cable configurations, an intervening material, a presser cloth tape,
It is also possible to provide inner and outer semiconducting layers in the same way as a normal cable. In this case, when the intervening material is made of a material that is flammable and easily drips, such as polypropylene or polyester tape, melting and outflow can be suppressed by the carbonized tape layer, which carbonizes when heated like the insulator, and the nonflammable tape layer. Examples of the present invention will be described below. <Example> A 1.0 mm thick cross-linked polyethylene was applied on a 4 mm (14 mm ² ) annealed copper stranded wire conductor, and these were twisted into a 3-core circular shape with jute interposed, and 2 pieces of 150 μm kraft paper were placed on top of this. Wrap each piece in 1/4 wrap. Next, a tape made by laminating asbestos tape with a thickness of 0.15 mm and polyethylene terephthalate film with a thickness of 25 μm is wrapped in a 1/4 wrap over this, and a flame retardant tape with a 0.1 value of 28 is wrapped on top of this. It was coated with polyvinyl chloride to a thickness of 1.5 mm. <Example> A 4 mm (14 mm ² ) annealed copper stranded wire conductor is coated with 1.0 mm thick cross-linked polyethylene, 3-wire cores are twisted in a circle with polypropylene stretched tape interposed, and a 0.1 mm kraft wire is placed inside. The paper is wrapped with a laminated tape consisting of 0.1 mm thick asbestos paper in the middle and 25 μm polyethylene terephthalate film on the outside. on this
Flame retardant polyvinyl chloride with a 0.1 value of 28 was coated with a thickness of 1.5 mm. <Example> Cross-linked polyethylene with a thickness of 1.0 mm was applied on a 4 mm (14 mm ² ) annealed copper stranded wire conductor, and these were twisted into a 3-core circular shape with jute interposed, and held down with chloroprene rubberized human silk tape. Roll. on this
Wrap one layer of 0.15mm thick alkyd varnished glass cloth tape with a 1/5 wrap, and then wrap 1.5mm of flame-retardant polyvinyl chloride with a 0.1 value of 28 on top.
coated in thickness. <Comparative example> Cross-linked polyethylene with a thickness of 1.0 mm was applied on a 4 mm (14 mm ² ) annealed copper stranded wire conductor, and these were twisted into a circular three-wire core with flame-retardant jute (0.1 value 35) interposed. Wrap it tightly with tape. For comparison purposes, a conventional product was manufactured in which a flame-retardant polyvinyl chloride with a 0.1 value of 35 was coated with a thickness of 1.5 mm. IEEE383
When the flame retardance was tested using the vertical tray combustion test specified in the American Standards, the results were as shown in the table below.
In this case, the cable will be completely burnt out at 180cm.

[Table] From this table, according to the cable with the configuration of this invention,
The carbonization tape layer and non-combustible tape prevent melting and outflow even when flammable and drip-prone cross-linked polyethylene is used as an insulator or polypropylene of the same quality is used as an intervening material, making it effective in preventing cable fire from spreading. It can be seen that this is effectively prevented. Therefore, it is no longer necessary to increase the flame retardance of the sheath material to such a degree that its properties deteriorate, and it becomes possible to use a cable sheath with an excellent composition that has reasonable properties. Additionally, the sheath material is therefore inexpensive. In contrast, conventional cables use highly flame-retardant juute,
It can be seen that even if a polyvinyl chloride sheath is used, the spread of fire cannot be sufficiently prevented. Although the above embodiments and multi-core cables have been described, the present invention is not limited thereto, and can of course be applied to single-core cables as well. As explained above, according to the present invention, the tape layer is made of a tape made of a material that is carbonized by heating, and the non-combustible tape made of an inorganic material other than metal is airtightly formed, so that it can be used in the event of a fire, etc. It has excellent properties as a sheath, with less melting and leakage of the insulator, intervening material, and other constituent materials made of flammable and drip-prone materials, and the flame retardance of the sheath material can be set easily. Moreover, it is possible to provide a flame-retardant cable that is inexpensive and has significantly improved flame retardancy as a whole.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional end view of a flame-retardant cable according to the present invention, and FIG. 2 is a side view of the flame-retardant cable with the end portion partially peeled off. 1...Conductor, 2...Insulator, 3...Wire core, 4...
...carbonized tape layer, 5... nonflammable tape layer made of inorganic material other than metal, 6... sheath.

Claims (1)

[Scope of utility model registration request] In a cable in which a flammable and drip-prone material is used for the insulator, intervening material, etc., and the insulating material, intervening material, etc. melts and flows outward under heated conditions, the insulating material, intervening material, etc. A carbonized tape layer such as human silk tape that carbonizes when heated is applied on the inside, and a non-flammable tape layer made of an inorganic material other than metal is airtightly applied on the outside. A flame-retardant cable characterized in that it is coated with a moderately compressed non-highly flame-retardant rubber or plastic sheath to prevent the insulator, intervening material, etc. from melting and flowing outward.