JP4809069B2 - Refractory wires and cables - Google Patents

Description

  The present invention relates to a refractory wire / cable used for electrical wiring of disaster prevention facilities such as buildings and underground malls.

  Fireproof wires and cables used as electrical wiring for disaster prevention facilities such as buildings and underground shopping malls have standards for fireproof performance, electrical characteristics, structure, dimensions, etc. stipulated by the Fire and Disaster Management Agency notification. The current “Fire Service Notification No. 10” is based on the fact that power can be supplied even under the temperature condition of the fire curve (840 ° C.-30 minutes) defined in JIS A 1304.

  As a refractory wire / cable that satisfies such fire resistance standards, for example, a refractory tape is wound around a conductor to form a refractory layer, and an insulator layer made of polyethylene, cross-linked polyethylene, etc. is provided on the refractory layer. A sheath made of vinyl chloride resin or flame retardant polyethylene, etc., or a refractory layer formed by wrapping a refractory tape on a conductor, and an insulator layer made of polyethylene, cross-linked polyethylene, etc. on it. As a fireproof insulation core, a plurality of, for example, three wires are twisted, and a sheath made of vinyl chloride resin, flame retardant polyethylene, or the like is provided on the outer periphery thereof (see, for example, Patent Document 1). .)

  By the way, as for the fireproof tape forming the fireproof layer, conventionally, a glass cloth is used as a base material (lining material), and a soft non-fired laminated mica foil is attached to one side thereof, or polyethylene, polyester, or the like Film mica tape with a plastic film as the base material and the same soft non-fired laminated mica foil on one side is used frequently because of its excellent fire resistance and electrical properties, and excellent winding workability. Yes.

  However, in such a refractory electric wire / cable using a mica tape, since the adhesion between the mica foil and the conductor is weak, the conductor protrudes beyond the end face of the cable after the insulator layer is extrusion coated. A protruding phenomenon sometimes occurred. This is due to shrinkage when the insulator layer is cured after extrusion, and the mica tape having weak adhesion to the conductor is pulled by the shrinking insulator layer, and as a result, the inner conductor is exposed. The reason why the adhesion between the mica foil and the conductor is weak is that, due to the properties of the above-mentioned laminated mica foil, there are irregularities on the surface, and a gap is formed between the conductor and the mica foil when wound on the conductor. Conceivable.

  Therefore, in order to prevent such a conductor protruding phenomenon, measures such as strongly pressing the refractory layer with a glass yarn are taken.

However, in this case, if the refractory layer is pressed too strongly by presser winding, there is a concern that the mica tape will crack during long-term use, and the fire resistance performance will be reduced.
JP 2001-202833 A

  As described above, a mica tape in which a soft non-fired laminated mica foil is attached to one side of a base material made of glass cloth or the like is frequently used as a material for the fireproof layer. However, the conventional refractory electric wires and cables using such mica tape have a problem that the phenomenon of the conductor being prone to occur. Therefore, as countermeasures, countermeasures such as strongly pressing the refractory layer are taken, but there is a risk that the mica tape may crack and the refractory performance may deteriorate.

  The present invention has been made in response to such problems of the prior art, and can increase the adhesion between the conductor and the mica tape without strongly pressing the refractory layer. An object of the present invention is to provide a high-quality and high-reliability fire-resistant electric wire / cable that does not cause a protruding phenomenon and can maintain excellent fire resistance over a long period of time.

In order to achieve the above object, the refractory wire / cable of the present invention is a refractory wire / cable comprising a refractory layer and an insulator layer in order on the outer periphery of a conductor, and the refractory layer is a mica layer on a substrate. Is formed by winding the mica layer with the mica layer side facing the conductor side, and an inorganic powder layer made only of silica powder is provided between the mica layer and the conductor. It is characterized by.

  According to the refractory wire / cable of the present invention, the inorganic powder layer is provided between the mica layer and the conductor of the mica tape forming the refractory layer. Since the adhesion with the mica tape can be increased, the conductor protrusion phenomenon associated with the insulation layer coating can be prevented, and excellent fire resistance can be maintained over a long period of time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

  As shown in FIG. 1, the refractory cable 10 of this embodiment has a structure in which a refractory layer 13, an insulator layer 14, and a sheath 15 are sequentially coated on a conductor 11 made of copper or the like via an inorganic powder layer 12. Have.

  As shown in FIG. 2, the inorganic powder layer 12 and the refractory layer 13 are made of a plastic film such as polyethylene and polyester having a thickness of about 25 μm as a base material (lining material) 16a, and have a thickness of about 0.15 mm on one side. After the inorganic powder 17 is attached to the mica foil side surface of the mica tape 16 to which the laminated mica foil 16b, for example, the soft non-fired laminated mica foil is attached, the mica having the inorganic powder 17 attached on the conductor 11 The foil 16b side is overlaid or vertically attached to the conductor 11 side, and the top is pressed with a glass yarn. In the present invention, in forming the inorganic powder layer 12 and the refractory layer 13, after the inorganic powder 17 is adhered on the conductor 11, the mica tape 16 is placed on the laminated mica foil 16b side on the conductor 11 side. You may make it wind toward. From the viewpoint of production efficiency, it is preferable to use the former method in which the inorganic powder 17 is previously attached to the surface of the mica tape 16 and wound around the conductor 11.

As a method for attaching the inorganic powder 17, a known method can be used. The amount of adhesion is preferably such that the inorganic powder 17 enters the recess G on the surface of the mica foil 16b and the surface unevenness is eliminated, and the range is usually 0.1 to 0.5 g / m ² . is there. If the amount of adhesion is too small, irregularities remain on the surface, and the adhesion with the conductor cannot be sufficiently improved, and there is a risk that the conductor will protrude. On the other hand, if the amount of adhesion is too large, the protrusion of the conductor is promoted and the periphery of the production line is contaminated. When the inorganic powder 17 is attached to the surface of the mica foil 16b, the inorganic powder 17 is selectively attached only to the surface of the mica foil 16b by covering the surface of the base material 16a. preferable. This is because, depending on the material of the substrate 16a, the adhesion of the mica tape 16 and the insulator layer 14 increases due to the adhesion of the inorganic powder 17, and the insulator layer 14 contracts when the insulator layer 14 is formed. In this case, the mica tape 16 is more easily pulled on the insulator layer 14 and the conductor protrusion phenomenon is likely to occur, so that the inorganic powder 17 is prevented from adhering to the surface of the base material 16a. Therefore, the occurrence of such a problem can be solved.

As the inorganic powder 17, silica, alumina, calcium carbonate, aluminum hydroxide, magnesium hydroxide powder, glass powder, and the like are used. Among them, since a stable particle diameter is easily available, silica powder is used. preferable. The particle size is preferably an average particle size of 1 to 100 nm and no particle size of 1000 nm or more, an average particle size of 5 to 50 nm and a particle size of 500 nm or more. It is more preferable that it does not contain the thing. If the average particle size is less than 1 nm, handling becomes very difficult, and if the average particle size exceeds 100 nm , it becomes difficult to enter the concave portion 16 on the surface of the mica foil 15b, and the adhesion with the conductor 11 is increased, and the protruding phenomenon of the conductor. There is a possibility that the effect of preventing the above cannot be sufficiently obtained. Similarly, when particles having a particle diameter of 1000 nm or more are included, it is difficult to enter the recess 16 on the surface of the mica foil 15b, and the effects of the present invention may not be sufficiently obtained. The average particle diameter can be measured using, for example, a laser diffraction particle size distribution measuring apparatus.

  The insulator layer 14 and the sheath 15 formed on the inorganic powder layer 12 and the refractory layer 13 are formed by extruding a resin based on polyolefin or polyvinyl chloride. Polyolefins include low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), polypropylene, polyisobutylene, ethylene Vinyl acetate copolymer (EVA), ethylene / ethyl acrylate copolymer (EEA), ethylene / methyl acrylate copolymer (EMA), ethylene / propylene copolymer, ethylene / propylene / diene terpolymer And ethylene-butene copolymer. Moreover, what copolymerized alpha-olefins, such as propylene, butene, pentene, hexene, octene, cyclic olefins, etc., with ethylene by the metallocene catalyst can also be used. These are used alone or in combination. Additives such as flame retardants, antioxidants, lubricants, UV stabilizers may be added to these resins as necessary, and these resins may be used with electron beams, organic peroxides, etc. It may be cross-linked. Examples of the flame retardant include metal oxides such as antimony oxide and molybdenum oxide, metal hydrates such as aluminum hydroxide and magnesium hydroxide, halogen flame retardants, and phosphorus flame retardants such as red phosphorus.

  In the present invention, the insulator layer 14 is formed of polyolefin or cross-linked polyolefin, and the sheath 15 is a resin based on polyvinyl chloride, or a resin based on polyolefin and containing a flame retardant, that is, flame retardant polyolefin. It is preferable to form by. The thicknesses of the insulator layer 14 and the sheath 15 are usually in the range of 0.8 to 2.8 mm and 1.5 to 3.5 mm, respectively.

  In the fireproof cable 10 configured as described above, the fireproof layer 13 made of the mica tape 16 in which the mica foil 16b is attached to one surface of the base material 16a is formed on the conductor 11 with the inorganic powder layer 12 interposed therebetween. Therefore, the gap between the conductor 11 and the refractory layer 13 is reduced as compared to the conventional refractory cable having a refractory layer formed by winding mica tape directly on the conductor 11, and the conductor of the refractory layer 13 is reduced. 11 is substantially improved. For this reason, it is possible to suppress or prevent the occurrence of the protruding phenomenon of the conductor 12 due to the contraction of the insulator layer 14 without strongly pressing with a glass yarn or the like as in the prior art. In addition, since it is not necessary to perform pressering strongly as described above, the mica tape 16 is not cracked during long-term use, and a reduction in fire resistance due to the crack is suppressed.

  The embodiment described above is an example in which the present invention is applied to a single-core fireproof cable. However, the present invention is not limited to such an embodiment. For example, FIGS. Needless to say, the present invention can be widely applied to various types of refractory wires and cables as well as multi-core refractory cables as shown.

  The fireproof cable 20 shown in FIG. 3 has a structure in which a plurality of fireproof cables 10 shown in FIG. 1 (three in the example of the drawing) are twisted together. Also, the fireproof cable 30 shown in FIG. 4 is provided with an inorganic powder layer 12, a fireproof layer 13, and an insulator layer 14 in this order on the conductor 11 to form a fireproof insulation core 18, and a plurality of these (in the example of the drawing, 2 pieces) are aligned, and a sheath 15 is provided on the outer periphery thereof. Although not shown, the sheath 15 may be extruded and coated in a pipe shape on the outer periphery of the aligned refractory insulated core 18. Furthermore, the refractory cable 40 shown in FIG. 5 twists a plurality of (three in the example of the drawing) refractory insulation cores 18 provided with the inorganic powder layer 12, the refractory layer 13, and the insulator layer 14 on the conductor 11. In addition, a presser tape 19B is wound around the gap via an interposition 19A, and a sheath 15 is provided on the outer side. For example, jute, paper, polypropylene yarn or the like is used for the interposition 19A. A plastic tape or the like is used for the presser tape 19B.

  In these fireproof cables 20, 30 and 40, since the fireproof layer 13 made of the mica tape 16 is provided on the conductor 11 with the inorganic powder layer 12 interposed therebetween, it is strongly pressed by a glass yarn or the like as in the prior art. Even without winding, the occurrence of the protruding phenomenon of the conductor 11 due to the contraction of the insulator layer 14 can be suppressed or prevented. Further, since it is not necessary to strongly press the presser, the mica tape 16 is not cracked during long-term use, and the deterioration of fire resistance due to the crack is suppressed.

  Next, although the Example of this invention is described concretely, this invention is not limited to the following Examples at all.

Examples 1-4
The amount of fumed silica powder shown in Table 1 (average) on the surface of the mica foil side of a film mica tape obtained by pasting a soft non-fired laminated mica foil of about 0.15 mm thickness on one side of a polyethylene film of about 25 μm thickness A particle size of 16 nm, a particle size of 10 to 40 nm) was attached, and this was overlaid on a copper conductor having a diameter of 2.0 mm with the mica foil side to which the silica powder was attached facing the conductor side to form a refractory layer. . On this refractory layer, low-density polyethylene (density 0.919 g / cm ³ , MFR = 0.9 g / 10 minutes) and flame-retardant polyethylene obtained by adding a flame retardant to the low-density polyethylene are sequentially coated by extrusion. Thus, an insulating layer having a thickness of about 0.8 mm and a sheath having a thickness of about 1.5 mm were formed, and a flat fireproof cable having an outer diameter of about 7 × 11 mm was manufactured.

Comparative Example A film mica tape in which a soft non-fired laminated mica foil having a thickness of about 0.15 mm is attached to one side of a polyethylene film having a thickness of about 25 μm is strongly wound with a glass yarn on a conductor without being treated with silica powder. A conventional fireproof cable was produced in the same manner as in the example except for the above.

  For the fireproof cables obtained in the above Examples and Comparative Examples, the amount of protrusion of the conductor was measured, and the presence or absence of cracks after the accelerated test of the fireproof layer (80 ° C., 24 hours) was examined. In addition, a fire resistance test (840 ° C. for 30 minutes) based on Notification No. 10 of the Fire Department was conducted to evaluate fire resistance. These results are also shown in Table 1. For Example 1 and the comparative example, the change with time of the protruding amount of the conductor was further examined. The result is shown in FIG.

  As is clear from these results, all of the fireproof cables of the examples had the conductor protruding amount suppressed as compared with the fireproof cable of the comparative example, and had good characteristics in terms of fire resistance.

It is sectional drawing which shows one Embodiment of the fireproof cable of this invention. It is sectional drawing which shows typically the state by which the silica powder was adhered to the mica tape. It is sectional drawing which shows other embodiment of the fireproof cable of this invention. It is sectional drawing which shows other embodiment of the fireproof cable of this invention. It is sectional drawing which shows other embodiment of the fireproof cable of this invention. It is a figure which shows the time-dependent change of the protrusion amount of the conductor of an Example and a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 20, 30, 40 ... Fireproof cable, 11 ... Conductor, 12 ... Inorganic powder layer, 13 ... Fireproof layer, 14 ... Insulator layer, 15 ... Sheath, 16 ... Mica tape, 16a ... Base material, 16b ... Mica foil 17 ... Inorganic powder, 18 ... Fireproof insulated core, 19A ... Intervening, 19B ... Presser tape

Claims (6)

A refractory wire / cable comprising a refractory layer and an insulator layer in order on the outer periphery of the conductor,
The refractory layer is formed by winding a mica tape having a mica layer on a base material with the mica layer side facing the conductor side, and only silica powder is interposed between the mica layer and the conductor. A refractory wire / cable characterized by being provided with an inorganic powder layer.   The refractory wire / cable according to claim 1, wherein the refractory wire / cable is a refractory cable specified in the Fire Department Notification No. 10.   The refractory wire / cable according to claim 1 or 2, wherein the inorganic powder layer is formed by attaching the silica powder on a mica layer of the mica tape and winding the silica powder on the conductor. . The silica powder refractory wire or cable according to any one of claims 1 to 3, wherein the adhered amount is in the range of 0.1 to 0.5 g / m ² of.   The refractory wire / cable according to any one of claims 1 to 4, wherein the silica powder has an average particle diameter of 1 to 100 nm and does not contain particles having a particle diameter of 1000 nm or more. . The refractory wire / cable according to any one of claims 1 to 4, wherein the silica powder has an average particle diameter of 5 to 50 nm and does not contain a particle diameter of 500 nm or more. .

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