JPH07320556A - Fireproofing cable - Google Patents

Abstract

PURPOSE:To provide a new fireproofing cable having high frame retardant and 4 excellent fireproofing characteristics. CONSTITUTION:In a fireproofing cable, a retainer tape 5 is wound to peripheries of insulator cores 4 coating on conductors 1 with insulators 3 through fire protecting layers 2, further to coat on this tape 5 with a sheath 6. The insulator 3 and the sheath 6 are formed of resin composition mixing metal hydroxide in polyolefin, and further the retainer tape 5 is formed of a woven fabric tape processed by coating or impregnated with a compound mixing metal hydroxide in polyolefin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fireproof cable used in a place where high safety is required, such as a building or an underground mall.

[0002]

2. Description of the Related Art Generally, as fire safety measures in buildings and underground malls, it is obligatory to install fire extinguishing equipment such as sprinklers and water spray equipment, as well as automatic fire alarms, emergency warning devices, and delinquent guidance display devices such as guide lights. For these electric facilities, a fireproof cable having excellent flame retardance and fire resistance is used.

As such a conventional fireproof cable,
For example, as shown in FIG. 2, a conductor 1 is wrapped with a refractory layer 2 such as glass mica, and insulating cores 4 and 4 are formed around the conductor 1 by covering an insulator 3 made of polyolefin such as polyethylene or cross-linked polyethylene. In addition, a flame-retardant sheath 6 is provided around it with an intervening member 7 and a holding tape 5.
It is possible to protect the insulator cores 4 and 4 from the high heat at the time of fire to operate the above equipment for a certain period of time and prevent the spread of fire due to the combustion of the cable. ing.

[0004]

By the way, heretofore, as such a fireproof cable, JIS-C-3005 No. 6 has been used.
The flame retardant that passes the 0 ° tilt test has become the mainstream, but recently, with the increase in the height of buildings and the expansion and deepening of underground malls, it passes the vertical tray combustion test of IEEE standard 383. There has been a demand for fire resistant cables with even better flame retardancy. In order to realize such high flame retardancy, it can be easily achieved by flame retarding the sheath 6 directly exposed to the flame as shown in the figure.

However, when the sheath 6 is made highly flame-retardant, conversely, in the fire resistance test according to JIS-A1304, particularly in the conduit test, the insulator 3 made of polyolefin such as polyethylene or cross-linked polyethylene melts down or burns. It becomes difficult and carbonized after being steamed, and as a result, electrical characteristics are greatly deteriorated, and it becomes difficult to satisfy the withstand voltage test and the insulation resistance standard value. That is, by making the sheath 6 highly flame-retardant, it is possible to prevent disconnection and spread of fire in an actual fire, but for the reasons described above, the electrical characteristics are significantly deteriorated and the original function of the cable for a certain period of time is achieved. There will be new problems such as being unable to maintain.

Therefore, the present invention has been devised in order to effectively solve the above problems, and an object thereof is to provide a novel fire resistant cable having excellent flame retardancy and fire resistance. is there.

[0007]

In order to solve the above-mentioned problems, according to the present invention, a pressing tape is wrapped around an insulating core in which a conductor is covered with an insulating material through a refractory layer, and a sheath is further provided thereon. In the coated fireproof cable, the insulator and the sheath are made of a resin composition in which a metal hydroxide is mixed with polyolefin, and the holding tape is treated by coating or impregnating a compound in which a metal hydroxide is mixed with polyolefin. It is made of woven fabric tape.

Polyolefins used for this insulator and sheath include polyethylene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene propylene rubber, ethylene butene copolymer, and the like. Each can be used alone or in combination of two or more.

Examples of metal hydroxides which are mixed with these polyolefins include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate and calcium aluminate. The amount of the admixture is preferably 50 to 200 parts by weight with respect to 100 parts by weight of these polyolefins. In addition to this, a silicone compound, carbon black, or the like can be added as a flame retardant auxiliary agent, and a peroxide may be added to a resin composition composed of these for chemical crosslinking or energy ray irradiation crosslinking.

Examples of the polyolefin for the compound for treating the woven tape include butyl rubber, ethylene propylene rubber, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer and the like. From the viewpoint, butyl rubber or ethylene vinyl acetate copolymer is preferable. Also,
As the metal hydroxide to be mixed with this, the same ones as mentioned above can be mentioned, but magnesium hydroxide is most preferable because it is flame retardant. The amount of admixture is preferably 200 to 400 parts by weight with respect to 100 parts by weight of polyolefin for imparting a high degree of flame retardancy. In addition to this, frit such as talc, clay, wollastonite, silicic acid, calcium carbonate, alumina, and mica powder may be added as a combustion solidifying agent. Then, these materials are kneaded by a roll, a Banbury mixer, a kneader, a twin-screw extruder or the like, and then, for example, this composition is subjected to toluene, benzene, xylene, n-
After being dissolved in an organic solvent such as hexane and adjusted to a viscosity of about 50 to 300 centipoise, a method of coating or impregnating on a woven fabric tape and drying, a method of extrusion coating on a woven fabric tape using an extruder, and the like are available. Conceivable. Further, it is desirable to use glass or staple as the woven tape. If necessary, the compound may be crosslinked with sulfur or peroxide.

[0011]

As described above, according to the present invention, the flame retardancy of the insulator and the sheath can be improved by using the resin composition in which the metal hydroxide is added to the polyolefin as the insulator and the sheath. Further, a woven fabric tape obtained by coating or impregnating a compound in which a metal hydroxide is mixed with polyolefin is further provided between the insulator core and the sheath having the above-described composition, specifically, on the insulator core, and the insulator core. By providing it as a tension member that imparts strength when winding the tape, such as by twisting it with the interposition of polypropylene yarn, etc., and on the shielding copper tape, etc., this woven fabric tape prevents fire spread and also becomes an insulator core. It can be fixed and the insulator can be sealed to suppress the blowout. The mechanism of this action is under intense investigation, but when observing the glass mica tape or film mica tape that forms the refractory layer directly on the conductor after the fire resistance test, these carbides adhere to the conventional polyethylene and crosslinked polyethylene insulators, causing blackening. On the other hand, in the case where the metal hydroxide is mixed, the amount of the carbide is significantly reduced and the color becomes white or gray.Therefore, in addition to the effect of reducing the polymer content by simply mixing the metal hydroxide, the metal hydroxide is It is presumed that carbides are actively suppressed. In addition, by winding a woven tape treated with a compound in which a metal hydroxide is mixed with polyolefin around a sheath and an insulator, the melting and blowing of the insulator are significantly suppressed without substantially lowering the fire resistance property. be able to. Therefore,
At the time of combustion, carbonization of the insulator due to fumigation is suppressed, and deterioration of electrical characteristics due to this is prevented.

[0012]

EXAMPLES Examples of the present invention will be described in detail below.

(Example) First, as shown in FIG. 1 and Table 1, 0.15 mm thick glass mica (0.10 mm mica thickness) was lapped on a 1.2 mmφ copper conductor 1 in two laps. After forming the refractory layer 2 by winding one sheet, a resin composition (I-1, I-2, I-3) shown in Table 2 having a thickness of 0.8 mm was formed on the refractory layer 2. The insulating core 3 was extruded and coated to form an insulating core 4. Next, 7 of the insulating cores 4 are twisted together, and the pressing tape 5 is ½ on the twisted core.
After wrapping and winding two sheets of wrap, the resin composition (J-1, J-2, J
-3) was covered with the sheath 6 to prepare three types of sample cables (Examples 1, 2, 3). Here, as the holding tape 5, a compound in which the materials shown in Table 3 are dissolved in toluene is applied to a soft tape or a woven cloth tape made of glass cloth in a thickness of about 30 μm, and then,
Those dried at 130 ° C. were used (T-1, T-
2).

Then, a vertical tray burning test and a fire resistance test were carried out on each of these sample cables, and the respective flame retardance and fire resistance were evaluated. As the vertical tray combustion test, a vertical tray combustion test method conforming to IEEE standard 383 was used. Seven sample cables set to a length of 2.4 m were arranged vertically, and 70.000 BTU / hr was set at the lower end.
Was applied for 20 minutes. After that, the flame was removed and 1.8
Passed if self-extinguishing at less than m, and rejected if fire spread by 1.8 m or more. On the other hand, as a fire resistance test,
In-service testing stipulated by the Heat Resistant Electric Wire Certification Committee
Various sample cables were heated for 30 minutes according to the fire temperature curve defined in S-A1304. When measuring, gather 7 wire cores into 3 and 4 and install one on the fixed wire.
The insulation resistance was measured. The collective wire core on the installation side and the collective wire core on the non-contact side were switched and measured. Each insulation resistance value was shown as a value obtained by multiplying the measured value after 30 minutes by the number of core wires on the non-contact side. In addition, after 30 minutes, a withstand voltage test of 1500 V / 1 minute was performed, and those that did not cause dielectric breakdown were passed, and those that caused dielectric breakdown were rejected.

(Comparative Example) Sample cables (Comparative Examples 1, 2 and 3) having the same constitution as that of the Example except that the materials shown in Table 1 were used as the insulator and the sheath or the holding tape were prepared and implemented. Each flame retardancy and fire resistance were evaluated by the same method as the example.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

As a result, as is clear from Table 1, all of the sample cables of Examples 1 to 3 according to the present invention passed the vertical tray burning test, and in the fire resistance test, the standard value (0. 4 MΩ ≦) was satisfied, and the withstand voltage test was also passed.

On the other hand, the resin composition (I-3, J) containing no magnesium hydroxide as the insulator and the sheath.
Both Comparative Example 3 and Comparative Example 3 using No. 3) failed the vertical tray burning test and the fire resistance test. Further, Comparative Example 2 using a 30 μm thick 66 nylon tape as the holding tape had relatively good fire resistance, but failed the vertical tray burning test.

[0022]

In summary, according to the present invention, since flame retardancy is improved and excellent fire resistance is exhibited, reliability at the time of fire is improved, which can greatly contribute to safety measures. Has excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a fireproof cable according to the present invention.

FIG. 2 is a sectional view showing an example of a conventional fireproof cable.

[Explanation of symbols]

 1 conductor 2 fireproof layer 3 insulator 4 insulator core 5 holding tape 6 sheath 7 intervening

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Kashimura 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hidaka Plant, Hitachi Cable, Ltd. (72) Inventor Kazuhiko Kobayashi 5 Hidakacho, Hitachi City, Ibaraki Prefecture 1-1-1 Hitachi Cable Co., Ltd. Hidaka Factory

Claims (3)

[Claims] 1. A fireproof cable comprising a conductor, a holding tape wound around an insulator core covered with an insulator through a fireproof layer, and a sheath covering the insulator tape, wherein the insulator and the sheath are polyolefin. A fire-resistant cable comprising a resin composition in which a metal hydroxide is mixed with, and the holding tape is a woven tape obtained by coating or impregnating a compound in which a metal hydroxide is mixed with polyolefin. 2. The resin composition comprises a polyolefin 10
The fire resistant cable according to claim 1, wherein 50 to 200 parts by weight of a metal hydroxide is added to 0 parts by weight. 3. The compound is polyolefin 1
The fire resistant cable according to claim 1, wherein 200 to 400 parts by weight of a metal hydroxide is added to 00 parts by weight.