JPH10208561A - Fire resistance wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain generation wrinkles of a fire resistance layer and improve fire resistance performance without imparting excessive heat or pressure to a collective mica tape including synthetic mica during formation of an insulation layer by providing a fire resistance layer having a collective mica tape including a synthetic mica on a conductor and an insulation layer having an olefin-based resin composition silane cross-linked or ionizing radiation cross-linked. SOLUTION: An insulation core wire in which a fire resistance layer and an insulation layer are formed on a conductor is provided with a sheath after being stranded together with an intervention, when a collective mica tape is used including a synthetic mica as a fire resistance layer an olefin-based resin composition is cross-linked by a specific cross-linking method, and an insulation layer is formed. In this case, as a cross-linking method, a silane cross-linking method or an ionizing radiation cross-liking method is employed, thereby even if a collective mica tape including a synthetic mica is employed for the fire resistance layer, excessive heat and pressure is not imparted to the collective tape including the synthetic mica during formation of the insulation layer. Therefore, generation of wrinkles of the fire resistance layer which causes degraded fire resistance performance can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a refractory layer on a conductor,
The present invention relates to a fireproof electric wire having an insulating layer, and to an improvement in fireproof performance.

[0002]

2. Description of the Related Art Fireproof electric wires, which are widely used, are shown in FIG.
As shown in FIG. 1, a structure in which a conductor 1 is provided with an insulated wire core 4 having a fireproof layer 2 made of mica tape and an insulating layer 3 made of plastic or the like, and a sheath layer 5 made of a vinyl chloride resin or an olefin resin. It has become. In FIG. 1, 4
The insulated wire cores are twisted together with the interposition 6,
The insulated wire core may be used as a single core. The laminated mica tape of the refractory layer 2 is obtained by laminating the laminated mica to one side of a backing material such as a plastic film or a glass cloth, and is wound or vertically wrapped on the conductor so that the laminated mica surface faces the conductor side. It is provided. Insulating layer 3
Is formed by providing a plastic such as an olefin-based resin composition.

[0003] Fire-resistant electric wires have the capability of supplying power for 30 minutes in the event of a fire as an emergency power supply cable. In addition to the general physical properties stipulated by the Electrical Appliance and Material Control Law and the like,
It is required to satisfy the fire resistance performance stipulated in the Fire Service Notification Standard No. 7 for fire resistant wires. This fire resistance is
It is evaluated by the fire resistance test specified by the "Fire and Heat Resistant Wire Certification Committee" of the Japan Electric Wire & Cable Makers Association. In this fire resistance test, the insulation strength, insulation resistance, and flammability of the insulated wire when the refractory wire is heated to 840 ° C. for 30 minutes according to a fire temperature curve specified in JIS A1304 are evaluated. By the way, in recent years, from the viewpoint of strengthening building safety measures, fire-resistant equipment has been required to have stricter fire resistance performance than before, and accordingly, fire-resistant electric wires have become even more severe than the current Fire Service Agency notification standards. Heating conditions,
For example, fire resistance performance that can withstand heating at 925 ° C. for 60 minutes has been required.

Conventionally, hard mica (for example, a composition formula: K) has been used as a mica laminated mica tape constituting a refractory layer.
Inorganic compounds represented by Al ₂ AlSi ₃ O ₁₀ (OH) ₂ ), soft mica (for example, composition formula: KMg ₃ AlS)
Natural mica called inorganic compound represented by i ₃ O ₁₀ (OH) ₂ ) is generally used. However, the insulation resistance of mica decreases as the temperature rises. Particularly, in the temperature range where the temperature of the mica exceeds 840 ° C., the hydroxyl group in the structural formula is decomposed and dehydrated. cause. So 60 minutes,
For fire-resistant electric wires that require high fire resistance performance that can withstand heating at 925 ° C., synthetic mica containing fluorine as a component or a composite mica tape using only synthetic mica may be used. Proposed. Such a fire-resistant electric wire is excellent in that high fire resistance can be achieved with almost no change in the configuration other than the fire-resistant layer.

[0005]

Further, since the fire resistance is improved by crosslinking the olefin resin composition constituting the insulating layer, a laminated mica tape containing synthetic mica is used as the fire resistant layer and the insulating layer is crosslinked. The fire-resistant electric wire using the olefin-based resin composition is expected to further improve the fire resistance performance and pass a more severe fire resistance test. However, fire-resistant electric wires using a synthetic mica tape containing synthetic mica as the fire-resistant layer and a crosslinked polyolefin resin composition cross-linked by chemical cross-linking as the insulating layer have a low dielectric strength when subjected to a fire resistance test. The problem of variability often occurred.

In view of the above problems, the present invention uses a laminated mica tape containing synthetic mica as a refractory layer, and uses a crosslinked polyolefin resin composition as an insulating layer.
An object of the present invention is to provide a fire-resistant electric wire having more excellent fire resistance performance.

[0007]

Means for Solving the Problems The inventors of the present invention have proposed a fire-resistant electric wire using a synthetic mica tape containing synthetic mica as a fire-resistant layer and a cross-linked polyolefin resin composition cross-linked by chemical cross-linking as an insulating layer. In pursuit of the cause of the decrease in dielectric strength in the fire resistance test, synthetic mica has poor affinity with the adhesive due to the influence of fluorine in the composition formula, so the adhesive used when assembling the synthetic mica,
The compatibility of the adhesive used when laminating the laminated mica and the backing material is inferior to natural mica, and the olefin-based resin composition is formed on a fire-resistant layer composed of a laminated mica tape containing such synthetic mica. When the chemical cross-linking is performed, the heat applied at that time causes the laminated mica tape of the refractory layer to expand or the interface between the backing material and the laminated mica to be shifted, and the expanded or shifted portion is also the same. Wrinkles due to the pressure applied during cross-linking, these wrinkles may cause a path for the conductive gas generated during heating and cause a decrease in insulation resistance, and adsorption of conductive ash at the wrinkles may occur. And found that the insulation resistance was remarkably reduced, and that a destruction path with wrinkles as a defect ran, which was the cause of destruction, etc., and completed the present invention. That is, the present invention is characterized in that a conductor is provided with a fire-resistant layer having a laminated mica tape containing synthetic mica and an insulating layer formed by crosslinking an olefin-based resin composition with silane or ionizing radiation. A refractory wire is provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The refractory electric wire of the present invention has a structure in which an insulated core wire having a refractory layer and an insulating layer formed on a conductor is twisted together with an interposition, and a sheath is provided. A semiconductive layer and a metal shielding layer made of copper tape or copper wire may be provided on the insulated wire core. The present invention is to form an insulating layer by cross-linking an olefin-based resin composition by a specific cross-linking method when a synthetic mica tape containing synthetic mica is used as the refractory layer having the above configuration.
In general, as a method of crosslinking an olefin-based resin, a method of crosslinking by reacting an organic peroxide to the resin, a silane crosslinking method of grafting a silane compound to the resin and crosslinking in the presence of water and a catalyst, ionizing radiation irradiation In the present invention, the method of crosslinking the refractory layer is limited to a silane crosslinking method or a crosslinking method by irradiation with ionizing radiation. In the chemical crosslinking method of heating and crosslinking an olefin-based resin composition containing a chemical crosslinking agent such as an organic peroxide, in order to complete the crosslinking, heat and pressurize at a higher temperature than in other crosslinking methods. It is not preferable because wrinkles occur in the laminated mica tape containing the synthetic mica of the refractory layer, resulting in a decrease in the fire resistance performance of the refractory wire. In the fire-resistant wire of the present invention, since the silane-based cross-linking method or the cross-linking method by ionizing radiation irradiation is used as the cross-linking method of the olefin composition forming the insulating layer, the mica tape including synthetic mica in the fire-resistant layer Even when using, the mica tape containing synthetic mica is not applied with excessive heat and pressure during the formation of the insulating layer, and the generation of wrinkles in the refractory layer that causes a decrease in the refractory performance can be suppressed.

In the present invention, the refractory layer formed on the conductor is composed of a mica tape containing synthetic mica.
The synthetic mica, artificially synthesized fluorine-based mineral is typically a composition formula _{KMg 2. 5 Si 4 O 10} F 2,
Some are represented by KMg ₃ AlSi ₃ O ₁₀ F ₂ or the like. The laminated mica tape used in the present invention is composed of synthetic mica, or a mixture of synthetic mica and natural mica, assembled with an adhesive and processed into a foil shape to form a laminated mica for a backing material such as a plastic film or glass cloth. Created by laminating on one side.

When a mica tape is provided on a conductor to form a refractory layer, the mica surface of the mica tape is vertically attached or horizontally wound with the mica surface facing the conductor.
The number of laminated mica tapes is appropriately selected in consideration of necessary characteristics, cost, and the like. In the present invention, all the mica tapes constituting the refractory layer need not be mica tapes including synthetic mica, and can be used in combination with conventional mica tapes made of natural mica.

The base resin of the olefin resin composition for forming the insulating layer includes at least one olefin resin selected from the group consisting of polyethylene, polypropylene, and ethylene-propylene copolymer. Even if an appropriate amount of an olefin resin modified with a vinyl copolymer, an ethylene ethyl acrylate copolymer, an ethylene methyl acrylate copolymer, an ethylene methyl methacrylate copolymer, an unsaturated carboxylic acid or a derivative thereof, etc. is used. Good.

Various flame retardants and flame retardant auxiliaries may be added to the resin composition of the present invention in order to further impart flame retardancy. Specific examples include magnesium hydroxide, aluminum hydroxide, zinc borate, calcium carbonate, hydrotalcite, magnesium oxide, molybdenum oxide, antimony oxide, and red phosphorus. In addition, additives such as a filler, an antioxidant, a lubricant, a dispersant, and a coloring agent can be added as necessary, in addition to the above components.

In the present invention, the insulating layer is formed by, for example, extruding a resin composition containing the above-mentioned components onto a refractory layer and cross-linking with silane or ionizing radiation.

In the case of silane cross-linking, cross-linking is performed in the presence of a silanol condensation catalyst and water using a resin composition obtained by mixing a silane compound and a radical generator with the above base resin. As the silane compound used in the silane crosslinking method,
Any material can be used as long as it can be crosslinked with silane, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinyltris (β-methoxyethoxy) silane. The silane compound is a component that is graft-polymerized with a radical in the base resin generated by the action of a radical generator described later and binds to the base resin. An appropriate amount of the silane compound is 0.5 to 10 parts by weight based on 100 parts by weight of the base resin.

Any radical generator may be used as long as it is used for silane crosslinking. For example, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne -3,1,3-bis (t-butylperoxydiisopropyl) benzene, t
-Butylcumyl peroxide, 4,4-di (t-butylperoxy) valeric acid-n-butyl ester,
Organic peroxides such as 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane and di-t-butyl peroxide can be mentioned. The amount of the radical generator is 0.01 to 5 parts by weight based on 100 parts by weight of the base resin.

As the silanol condensation catalyst, any catalyst may be used as long as it is used for crosslinking a silane compound. For example, dibutyltin dilaurate, stannous acetate, stannous octoate, lead naphthenate, capric acid Carboxylates such as zinc, 2-ethylhexaneiron and cobalt naphthenate; and titanates such as tetrabutyl titanate, tetranonyl titanate, and bis (acetylacetonitrile) diisopropyl titanate. The silanol condensation catalyst is usually previously blended with the base resin. The compounding amount to the base resin is 0.001 to 5 per 100 parts by weight of the base resin.
Set to parts by weight.

When the insulating layer is formed by crosslinking by a silane crosslinking method, first, an olefin resin composition in which the above-mentioned components are mixed is prepared, and the composition is coated on a refractory layer. A cross-linking treatment is performed in the presence to form an insulating layer. In the case of silane cross-linking, a commercially available silane cross-linking compound may be used. For example, Mitsubishi Chemical Corporation's Rinklon X XH800 (a low-density polyethylene-based silane cross-linking compound) may be used. ) LZ013 (catalyst masterbatch).

The insulating layer is made of ionizing radiation such as an electron beam, γ
In the case of forming by crosslinking by irradiation with a ray, after providing the olefin-based resin composition on the refractory layer, the crosslinking is performed by irradiating with ionizing radiation. The irradiation dose of the ionizing radiation is appropriately adjusted depending on the ionizing radiation, the type of the resin of the insulating layer, and the thickness of the insulating layer.

In any of the cross-linking methods, a cross-linking aid such as trimethylolpropane triacrylate or divinylbenzene can be added as required.

[0020]

EXAMPLES The present invention will be described below more specifically based on examples. (Example 1) A mica surface of a 0.15 mm-thick mica tape formed by laminating a polyethylene film and synthetic mica laminated on a soft copper stranded wire conductor having a conductor cross-sectional area of 1.25 mm ² with the mica surface facing the conductor 1 / 4 wrapped. The same mica tape was further wound twice to form a refractory layer. Subsequently, an olefin-based resin composition obtained by mixing vinyl trimethoxysilane in an amount of 2 parts by weight, dicumyl peroxide in an amount of 0.15 parts by weight, and dibutyltin dilaurate in an amount of 0.05 part by weight with respect to 100 parts by weight of polyethylene was coated on the refractory layer. After extrusion coating at a resin temperature of 200 ° C., silane crosslinking was carried out in warm water at 90 ° C. to form an insulating layer having a thickness of 0.8 mm, thereby obtaining an insulating core. The obtained insulated wire cores 4 are twisted together with a polypropylene string as an intermediary, and the top thereof is pressed and wound with a polyester tape, and a resin composition in which magnesium hydroxide is mixed with an ethylene-ethyl acrylate copolymer is further placed thereon. Extrusion was performed to form a flame-retardant sheath having a thickness of 1.5 mm, and a fireproof electric wire of Example 1 having a size of 7 × 1.25 mm ² was obtained.

Example 2 A linear low-density polyethylene was used as an olefin resin composition for forming an insulating layer, and an electron beam (at an acceleration voltage of 750 keV and a dose of 30 Mra) was used.
A fire-resistant electric wire of Example 2 was produced in the same manner as in Example 1 except that crosslinking was performed by irradiation with d).

Example 3 A fire-resistant electric wire of Example 3 was produced in the same manner as in Example 1 except that a glass cloth was used as a backing material for the mica tape.

Comparative Example 1 2 parts by weight of dicumyl peroxide and 100 parts by weight of low-density polyethylene, an antioxidant (Nocrack 300, manufactured by Ouchi Shinko Co., Ltd.) 0.3
Using an olefin-based resin composition mixed at a ratio of parts by weight, the composition was extrusion-coated at a resin temperature of 130 ° C. on the refractory layer to obtain a coating composition of 180 parts.
A refractory wire of Comparative Example 1 was produced in the same manner as in Example 1 except that dry crosslinking was performed by heating and pressurizing at 10 ° C. and 10 kg / cm ² .

Comparative Example 2 The same procedure as in Example 1 was carried out except that a laminated mica tape composed of natural mica (soft mica) laminated with a polyethylene film was used as the laminated mica tape of the refractory layer. Thus, a fire-resistant electric wire of Comparative Example 2 was produced.

The obtained Examples 1 to 3 and Comparative Examples 1 and 2
The sheath layer and the insulating layer were peeled off from the fire-resistant electric wire of No. 5, and the fire-resistant layer was observed to check for wrinkles. Table 1 shows the results.
Shown in The following tests were performed according to the exposure test notified by the Fire and Disaster Management Agency, and fire resistance was evaluated. A fireproof electric wire sample of 1.3 m was horizontally mounted on a perlite plate, and a load twice as much as the weight of the fireproof electric wire was applied to the center of the fireproof electric wire. In this state, JIS A
Stored in a refractory furnace specified in 1305, JIS A13
According to the fire temperature curve specified in No. 04, the temperature was raised from room temperature to 925 ° C. in 60 minutes. At this time, during heating, AC60
At 0 V, before and after heating, AC 1500 V was applied for 1 minute.

(1) Dielectric Strength Those that withstand the application during and after heating were accepted, and those that caused dielectric breakdown as a result of the application were rejected. (2) Insulation resistance Connect three of the seven insulated core wires to the fixed wire (ground side),
The insulation resistance between the grounded side and the remaining four adjacent cores (non-grounded side) was measured. A pass was obtained if the value obtained by multiplying the measured value by the number 3 of the non-ground side wire cores was 0.4 MΩ or more, and a failure was obtained if the value was less than 0.4 MΩ.

If both of the items (1) and (2) were acceptable, it was evaluated as ○, and if any of the items was unacceptable, it was evaluated as x. These results are also shown in Table 1.

[0028]

[Table 1]

As is clear from Table 1, the fire-resistant electric wires of Examples 1 to 3 were formed by using a laminated mica tape containing synthetic mica as a fire-resistant layer, and by crosslinking the insulating layer by silane crosslinking or electron beam irradiation. Therefore, no wrinkles were observed in the refractory layer, and the refractory test passed a heating condition of 925 ° C. for 60 minutes. On the other hand, in the fire-resistant wire of Comparative Example 1, the fire-resistant layer was composed of a laminated mica tape containing synthetic mica, but the insulating layer was cross-linked by a chemical cross-linking method. The test failed. Further, the fire-resistant wire of Comparative Example 2 failed the fire resistance test because the insulating layer was formed by silane crosslinking, but the laminated mica tape containing synthetic mica was not used as the fire-resistant layer.

[0030]

The fire-resistant electric wire according to the present invention uses a laminated mica tape containing synthetic mica as a fire-resistant layer, and employs silane cross-linking or ionizing radiation irradiation cross-linking as a method of cross-linking the insulating layer. Performance can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a fireproof electric wire structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor 2 Fireproof layer 3 Insulating layer 4 Insulated wire core 5 Sheath 6 Interposition

Claims (1)

[Claims] 1. A fire-resistant electric wire comprising a fire-resistant layer having a mica tape including synthetic mica and an insulating layer formed by cross-linking an olefin resin composition with silane or ionizing radiation on a conductor. .