JPH11213770A - Fire resistant wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep excellent high-temperature insulating characteristic and withstand voltage characteristic and impart sufficient flexibility by covering a linear conductor with a fire resistant rubber layer consisting of fire resisting rubber obtained by blending powder mica and zinc borate to silicone rubber followed by cross-linking and a fire resistant reinforcing layer consisting of a composite mica sheet. SOLUTION: A fire resisting rubber layer 3a of obtained by cross-linking a rubber composition constituting power mica and zinc borate blended to silicone rubber by use of a peroxide vulcanizing agent and a platinum catalyst and a fire resistant reinforcing layer 3b consisting of a composite mica sheet are successively provided on the circumference of a linear conductor 2 to provide a fire resistant layer 3. This fire resisting core wire is covered with an insulating layer 4, and further covered with a sheath 5 to form a fire resisting wire 1. The powder mica blended to the fire resistant rubber layer 3a has a diameter of 50 μm or more, and the blending quantity is preferably set to 250 pts.wt. or less to 100 pts.wt. of silicone rubber. The blending quantity of zinc borate is preferably set to 15 pts.wt. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of withstanding use for a long time even when exposed to high heat or flame due to a fire or the like.
The present invention relates to a fire-resistant electric wire having a synthetic resin insulating layer.

[0002]

2. Description of the Related Art Generally, in places where many people gather, such as theaters and department stores, when an emergency such as a fire occurs, it is necessary to safely guide people in the hall to an emergency exit. In such a case, even if the emergency exit guide light itself is not destroyed, if the power transmission wire is exposed to high heat, flame, etc., a short circuit may occur in a short time and the power transmission may stop. There is. However, since the emergency exit guide light is required to be lit for a certain period of time, the electric wire for supplying power to the emergency exit guide light does not break the insulation even when exposed to high heat, flame, etc. It must be possible to supply.

[0003] Some refractory wires used for such a purpose have a structure as shown in FIG. That is, the fire-resistant electric wire 1 is formed by forming a fire-resistant layer 3 on the outer periphery of a conductor 2, covering the outer periphery with an insulating layer 4 made of polyethylene, and further covering the outer periphery with a sheath 5. The fireproof layer 3 of the fireproof electric wire 1 is made of a mica sheet formed by bonding a mica layer to a base film such as a glass fiber cloth or a polyethylene film, and has a thickness of 0.01 m.
It is formed by winding a fire-resistant tape of about 0.2 mm or so.

[0004] Such a fire-resistant electric wire has a fire resistance certification standard defined by the Fire Service Agency Notification No. 7 (the insulation resistance immediately after heating to 840 ° C for 30 minutes is 0.4 MΩ or more, the withstand voltage is 1500 V, and the withstand voltage is 1 minute. In order to satisfy condition (2), the above-mentioned two or three refractory tapes are wound by １ ／ to ４ overlap or wound vertically, so that the thickness of the refractory layer is 300 to 1200 μm. When the sheath is coated on the refractory layer, the electric wire becomes thicker, and not only the flexibility is poor but also the weight cannot be reduced, and there is a problem that the handleability is poor.

Therefore, in recent years, a method of forming a refractory layer of a ceramic film on a conductor by using a dipping method in which a conductor is immersed in a coating solution containing ceramic particles and a silicone-based resin and run (for example, Japanese Patent Publication No. 63-3
No. 7922). However, this method can provide general heat-resistant insulation and withstand voltage characteristics, but the insulation and withstand voltage characteristics at high temperatures of 840 ° C. or higher, which are the fire resistance certification standards according to the Fire Service Agency Notification No. 7 above. Was not enough to satisfy

Further, in order to conform the heat resistance of the fire-resistant electric wire to the fire resistance certification standard notified by the Fire and Disaster Management Agency, the above-mentioned dipping method is improved, and a methylphenyl silicone resin, a diluent, a silane coupling agent and 3 μm A fire-resistant electric wire formed by dipping a conductor into a mixture of talc having the following particle size to form a fire-resistant layer, further covering the fire-resistant layer with an insulator such as polyethylene, and further covering a sheath. Has also been proposed (JP-A-7-105733).

[0007]

However, such an improved refractory wire has no particular problem in performance when a single-wire conductor suitable for ordinary use is used, but it is used in applications where workability is required. If you try to use a highly flexible stranded wire conductor for the purpose, not only will the thickness of the refractory layer become uneven, but also the smoothness of the surface will be lost. There was a problem that the standard could not be met.

The present invention has been made to solve the problems of the prior art, and retains excellent high-temperature insulation characteristics and withstand voltage characteristics even when a stranded conductor is used, as in the case of using a single-wire conductor. It is an object of the present invention to provide a fire-resistant electric wire having sufficient flexibility.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
A fire-resistant rubber layer formed by crosslinking a rubber composition in which powdered mica and zinc borate are blended with silicone rubber with a peroxide-based vulcanizing agent and a platinum-based catalyst, and a fire-resistant reinforcing layer made of a mica sheet. The present invention can be achieved by a fire-resistant electric wire characterized in that an insulating layer and a sheath are further sequentially coated on a fire-resistant wire core provided sequentially around a linear conductor.

Further, in the refractory wire of the present invention,
The powder mica compounded in the fire-resistant rubber layer preferably has a diameter of 50 μm or more, and the compounding amount is preferably 250 parts by weight or less based on 100 parts by weight of the silicone rubber. The amount of zinc borate to be added to the fire-resistant rubber layer is preferably 15 parts by weight or less based on 100 parts by weight of the silicone rubber.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fire-resistant electric wire according to the present invention has a structure essentially similar to that of a conventional fire-resistant electric wire as shown in FIG. 1, except that a fire-resistant layer 3 has a fire-resistant rubber layer 3a and a fire-resistant reinforcement. Layer 3b
It consists of The fire-resistant rubber layer 3a is formed by extrusion-coating a silicone rubber composition having a specific composition in which powdered mica as an inorganic fire-resistant agent and zinc borate as a flame retardant are blended around the linear conductor. The fire-resistant reinforcing layer 3b is formed by winding a tape-shaped laminated mica sheet in which flake-like mica is adhered in a layer on a reinforcing base material at least once around the fire-resistant rubber layer 3a. , Different from conventional fire-resistant wires. However, on the refractory wire core having the refractory layer 3 having such a structure, an insulating layer 4 is further provided.
And the sheath 5 is coated on the insulating layer 4 in the same manner as the conventional fire-resistant electric wire.

In the fire-resistant electric wire of the present invention, the silicone rubber used for the fire-resistant rubber layer is preferably a millable silicone rubber such as one called HTV, but it can be coated on the linear conductor to a desired thickness. If so, it is not limited to this. Examples of such silicone rubber include polymers containing a functional group such as dimethyl, methylvinyl, methylphenylvinyl, and methylfluoroalkyl.

Examples of the vulcanizing agent to be blended with the silicone rubber include organic peroxides such as dicumyl peroxide, dibenzoyl peroxide, di-2,4, dichlorobenzoyl peroxide, and t-butyl perbenzoate. Oxides and the like can be mentioned, and such vulcanizing agents can be appropriately selected according to the type of silicone rubber used and desired vulcanizing conditions. The platinum-based catalyst used in combination with the vulcanizing agent has a remarkable effect on improving the fire resistance of the electric wire, but can be used as long as it is generally used for crosslinking silicone rubber. . The amounts of these vulcanizing agents and platinum-based catalysts can be determined as appropriate,
Usually, the vulcanizing agent may be in the range of 1 to 3% by weight, and the platinum-based catalyst may be in the range of 0.1 to 0.5% by weight, based on the silicone rubber.

In the fire-resistant rubber layer of the fire-resistant wire of the present invention,
As the inorganic filler compounded in the silicone rubber, powdered mica is used among silicic fillers and the like from the viewpoint of heat resistance. Among them, powdered mica having a particle size (average particle size) of 50 μm or more is preferable. The particle size distribution is preferably such that the maximum particle size does not exceed 2.5 mm from the viewpoint of uniform dispersion. The compounding amount of such powdered mica is 250 parts by weight or less per 100 parts by weight of silicone rubber, especially 5 to 5 parts by weight.
Desirably, it is in the range of 200 parts by weight. When the amount of the powdered mica is less than 5 parts by weight, the effect of improving the fire resistance is not clear, and when the amount is more than 250 parts by weight, the withstand voltage characteristics are impaired.

A flame retardant is added to the silicone rubber filled with the powdered mica as described above in order to further improve the fire resistance. As such a flame retardant, zinc borate is particularly preferably used. For example, good results cannot be obtained with metal hydroxides such as aluminum hydroxide and magnesium hydroxide and ordinary inorganic flame retardants such as antimony trioxide. The amount of zinc borate is preferably about 0.1 to 10 parts by weight per 100 parts by weight of silicone rubber.

Further, silicone oil or the like can be added to the silicone rubber used in the present invention, if necessary, in order to avoid a decrease in extrusion processability due to an increase in the amount of a filler or a flame retardant. The amount of the silicone oil used as the processing aid is not particularly limited, but is generally in the range of about 1 to 20 parts by weight per 100 parts by weight of the silicone rubber.

The above-described rubber composition based on silicone rubber is extrusion-coated on a linear conductor composed of a single wire or a stranded wire, and then guided to a heating device to be cured to form a fire-resistant rubber layer. However, in the present invention, by further forming a fire-resistant reinforcing layer on the fire-resistant rubber layer,
For the first time, a refractory layer with excellent performance is obtained.

The fire-resistant reinforcing layer used in the fire-resistant electric wire of the present invention is formed by winding a tape made of a laminated mica sheet using mica as a fire-resistant material. Such a tape is made of artificial fibers such as rayon or acetate. For example, polyester fibers, polyamide fibers, synthetic fibers such as polyolefin fibers, woven or non-woven fabric formed of inorganic fibers such as glass fibers, or, for example, polyethylene, on a reinforcing substrate such as a film of polyester,
For example, it is made of a sheet in which flake-like mica having a diameter of 0.2 mm or less is adhered in a layered form and, if necessary, sandwiched by the above-mentioned reinforcing base material. The laminated mica sheet preferably has a thickness of about 0.01 to 0.2 mm, has good flexibility, and has a tensile strength of 0.1 kg / cm or more. The tape made of such a sheet is wrapped at least once or more on the above-mentioned fire-resistant rubber layer by a method such as lap winding or longitudinal attachment to form a fire-resistant reinforcing layer.

The fire-resistant core obtained by laminating such a fire-resistant rubber layer and the fire-resistant reinforcing layer on a conductor is as follows:
If necessary, a plurality of fibers are bundled to form a multi-core or a single core is covered with an insulating layer. This insulating layer is formed by extrusion-coating an insulating synthetic resin composition using a conventional technique.
For example, olefin resin compositions such as polyethylene and polypropylene are preferably used. After covering with such an insulating layer, if necessary, a plurality of fibers are bundled into a multi-core, or a single-core, or a plurality of the fibers are arranged in parallel, and a protective sheath or the like is placed thereon. By extrusion coating, the fire-resistant electric wire of the present invention is obtained.

[0020]

EXAMPLES TSF-201 (methyl vinyl silicone) manufactured by Toshiba Silicone Co., Ltd. as silicone rubber (SR), TC-20B manufactured by Toshiba Silicone Co., Ltd. as vulcanizing agent (CA),
TC- made by Toshiba Silicone Co., Ltd. as a platinum-based catalyst (CAT)
20A, powdered mica (M), talc (TC) and silica (SI
L), zinc borate (ZB), antimony trioxide (STO), magnesium hydroxide (MHO) and aluminum hydroxide (AHO) as a flame retardant were compounded and kneaded according to the composition shown in Table 2, and each was fireproof rubber. A silicone rubber composition for a layer was prepared.

[0021]

[Table 1] M-1: Japanese mica, Kirara, particle size 40 µm, particle size 5
45 μm M-2: Japanese mica, Kirara, particle size 52 μm, particle size 10
６０60 μm M-3: Japanese mica, Kirara, particle size 500 μm, particle size 1
50-1130 μm TC: Fujitalc, MLS100, particle size 1.9 μm,
SIL: Nippon Aerosil, R972, particle size 16 nm

[0022]

[Table 2]

On the other hand, a stranded copper conductor having a cross-sectional area of 2 mm ² (diameter 1.
8 mm), each of the above silicone rubber compositions was coated at an extrusion temperature of 60 ° C. by an extruder, and further coated for 20 minutes.
After passing through a 0 ° C. tubular vulcanizer, a wire core having a diameter of 2.6 mm was obtained. Next, a tape composed of a mica sheet having a thickness of 0.1 mm is vertically applied to these cores so that the thickness becomes about 0.2 mm, and after being wound with glass fiber, a polyethylene insulating layer is extrusion-coated thereon. Thus, an insulated wire having a diameter of 4.5 mm was obtained. Thereafter, a polyethylene sheath was further extrusion-coated to obtain a fire-resistant electric wire having an outer diameter of 12.5 mm. For comparison, an electric wire without a fireproof reinforcing layer of the mica sheet was also manufactured.

An appearance inspection and a flexibility test were performed on a core sample from which the sheath and the insulating coating were removed from each of the refractory wires thus obtained. In addition, the samples cut out from the fire-resistant electric wire were tested for insulation properties at room temperature and withstand voltage properties at room temperature, and insulation properties and withstand voltage properties when heated to 840 ° C in 30 minutes, and the test results were summarized. Table 2 also shows the results. In addition, these test methods and criteria are as follows.

(1) Appearance Inspection The surface of the refractory layer of the wire core sample was visually inspected. (2) Flexibility The core sample was wound around a mandrel having a diameter of 10 mm.

(3) Room temperature insulation A vertical 300 mounted vertically on a carriage that can enter and exit the heating furnace.
mm, 300mm wide and 10mm thick pearlite plate,
A refractory electric wire sample having a length of 1.3 m was horizontally attached and fixed using soft copper wires each having a diameter of 1.6 mm at two positions 20 cm apart from each other at the center. At both ends of a bundle of two 40 cm long soft copper wires having a diameter of 1.6 mm are wound around the center of the mounting position at an interval of about 13 mm, and a 1.3 m long fireproof wire is wound around the center of the soft copper wire. A load equivalent to twice the weight of the electric wire was applied. Then, a DC voltage of 500 V was applied between the wire core conductor and the fixed wire, and the insulation resistance at room temperature was measured.

(4) Room Temperature Withstand Voltage Following the above-mentioned room temperature insulation property measurement, a commercial AC voltage of 1500 V was applied between the core conductor and the fixed wire. , And those that were not were marked as x.

(5) High-Temperature Insulation After performing the above-mentioned normal-temperature withstand voltage measurement, the bogie on which the sample of the fire-resistant electric wire was attached was introduced into the heating furnace, and the heating furnace was continuously applied with a commercial AC voltage of 600 V. 840 in 30 minutes
The temperature was raised to ° C. In this state, 5
A DC voltage of 00 V was applied to measure the insulation resistance.
Those having a resistance value of 4 MΩ or more were evaluated as ○, and those having no resistance were evaluated as ×.

(6) High-Temperature Withstand Voltage Following the above-mentioned high-temperature insulation measurement, a commercial AC voltage of 1500 V was applied between the conductor and the fixed wire. Those that were not were evaluated as x.

According to the test results shown in Table 2, powder mica, particularly powder mica having a particle size of 50 μm or more, was compounded up to 200 parts by weight per 100 parts by weight of silicone rubber, and zinc borate was compounded as a flame retardant. A fire-resistant electric wire in which a fire-resistant rubber layer cross-linked by using a vulcanizing agent and a platinum-based catalyst in combination with a fire-resistant reinforcing layer made of mica sheet is provided by a normal inorganic material, such as that conventionally used as a fire-resistant material. Particularly improved high-temperature withstand voltage, compared to a fire-resistant electric wire having a rubber layer composed of a silicone rubber composition containing a filler and a fire-resistant layer composed of a fire-resistant reinforcing layer, or a fire-resistant electric wire omitting reinforcement by a mica sheet. You can see that it is done.

When the amount of zinc borate as a flame retardant in the silicone rubber composition exceeds 15 parts by weight, or when a vulcanizing agent not using a platinum-based catalyst in the silicone rubber composition is used, In any case, it is found that the high-temperature insulation characteristics of the refractory wire are unfavorably reduced.

[0032]

The fire-resistant electric wire of the present invention comprises a silicone rubber composition comprising a powdered mica as a fire-resistant inorganic filler and zinc borate as a flame retardant, and a vulcanizing agent and a platinum-based catalyst in combination. With a configuration provided with a combination of a rubber layer and a fireproof reinforcement layer made of mica sheet,
Even with a core wire using a stranded conductor, it has both advanced insulation properties conforming to the Fire Protection Agency Notification No. 7 fire resistance certification standards and excellent high-temperature withstand voltage properties, and greatly increases production efficiency. It has the effect of being improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a fireproof electric wire according to the present invention.

FIG. 2 is a cross-sectional view showing a structure of a fire-resistant electric wire according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fireproof electric wire 2 Conductor 3 Fireproof layer 3a Fireproof rubber layer 3b Fireproof reinforcement layer 4 Insulation layer 5 Sheath

Claims (4)

[Claims] 1. A mica sheet comprising a fire-resistant rubber layer formed by crosslinking a rubber composition obtained by mixing powdered mica and zinc borate with silicone rubber with a peroxide-based vulcanizing agent and a platinum-based catalyst. A fire-resistant electric wire characterized in that a fire-resistant reinforcing layer is sequentially provided around a linear conductor, and an insulating layer and a sheath are further sequentially coated on a fire-resistant core. 2. The fire-resistant wire according to claim 1, wherein the powder mica is a powder mica having a diameter of 50 μm or more. 3. The fire-resistant wire according to claim 1, wherein the powdered mica is blended in an amount of 250 parts by weight or less based on 100 parts by weight of the silicone rubber. 4. The composition according to claim 1, wherein zinc borate is blended in an amount of 15 parts by weight or less based on 100 parts by weight of the silicone rubber.
4. The fire-resistant electric wire according to any one of claims 1 to 3.