JP3424803B2 - Fire resistant wire - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention can withstand long-term use even when exposed to high heat or flame due to fire or the like.
The present invention relates to a fireproof electric wire having a synthetic resin insulating layer.

[0002]

2. Description of the Related Art Generally, in a place where a large number of people gather, such as in a theater or a department store, it is necessary to safely guide people in the hall to an emergency exit when an emergency situation such as a fire occurs. 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 or flame, a short circuit may occur in the wire in a short time and power transmission may stop. There is. However, since the emergency exit guide light is required to be turned on for a certain period of time, the electric wire for supplying power to the emergency exit guide light does not destroy the insulation even when exposed to high heat or flame, and the It is necessary to be able to supply.

Some refractory electric 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 the fire resistant layer 3 on the outer circumference of the conductor 2, covering the outer circumference with the insulating layer 4 made of polyethylene, and further covering the outer circumference with the sheath 5. The fireproof layer 3 of the fireproof electric wire 1 is made of a laminated 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.
It is constructed by winding a fire resistant tape of about 0.2 mm.

Such a fireproof wire satisfies the fireproof tape 2 as described above in order to satisfy the insulation characteristics and the withstand voltage characteristics at a high temperature of 840 ° C. or higher, which are the fireproof certification standards defined by the Fire Service Agency Notification No. 7. Since it was manufactured by wrapping ~ 3 sheets in a ½ to ¼ stack or by wrapping them vertically, the thickness of the refractory layer is 450 to 600 μm, and if the sheath is coated on the refractory layer, the wire becomes thicker. As a result, not only the flexibility is poor, but also the weight cannot be reduced, and the handleability is poor.

Therefore, in recent years, a method of forming a refractory layer of a ceramic coating on a conductor by using a dipping method in which a conductor is dipped and run in a coating solution containing ceramic particles and a silicone resin (for example, Japanese Patent Publication No. 63-3
No. 7922) has been proposed. However, with this method, it is possible to have general heat resistance and withstand voltage characteristics, but the fire resistance certification standard (insulation resistance value immediately after heating to 840 ° C for 30 minutes is set by the Fire Service Agency Notification No. 7). With 0.4 MΩ or more, the withstand voltage could not satisfy 1500 V, 1 minute breakdown voltage).

Further, a methylphenyl silicone resin is used as an electric wire which improves the surface smoothness of the fireproof electric wire obtained by the dipping method and has flexibility, and which further complies with the fireproof certification standard of the above-mentioned Fire Service Agency notification. A conductor is dipped in a mixed solution of a diluent, a silane coupling agent, and talc having a particle size of 3 μm or less to form a refractory layer, and the refractory layer is covered with an insulator such as polyethylene, and a sheath is further formed. There has been proposed a structure in which the above is coated (Japanese Patent Laid-Open No. 7-105733).

[0007]

However, such an improved refractory electric wire has no particular problem in performance when a single-wire conductor suitable for ordinary use is used, but it is required for workability. If you try to use a highly flexible stranded conductor, the thickness of the fireproof layer becomes uneven and the surface smoothness is lost. There was a problem that it could not be satisfied.

The present invention has been made in order to solve the problems of the prior art, and even when a stranded wire conductor is used, excellent high temperature insulation characteristics and withstand voltage characteristics are maintained as in the case where a single wire conductor is used. In addition, it is an object of the present invention to provide a refractory electric wire which has sufficient flexibility and improved workability with high productivity and economically.

[0009]

The above object of the present invention is to:
On the linear conductor, a fire resistant layer made of a double rubber layer made of silicone rubber filled with powdered mica containing a flame retardant, silicone oil and stearic acid, and an insulating layer made of synthetic resin were sequentially provided. It is a fire resistant wire,
Zinc borate, based on 100 parts by weight of silicone rubber
15 parts by weight or less, and stearic acid is silicone
25 parts by weight or less are mixed with 100 parts by weight of rubber and powder
If the mica powder has a diameter of 50 μm or more
250 parts by weight or less per 100 parts by weight
One, silicone oil is 100 parts by weight of silicone rubber
It can be achieved by a fire resistant electric wire containing 35 parts by weight or less .

[0010]

[0011]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The fireproof electric wire of the present invention has a structure essentially similar to that of a conventional fireproof electric wire as shown in FIG. 1, except that the fireproof layer 3 has a rubber layer 3a and a rubber layer 3b. And has a double structure. The rubber layer 3a and the rubber layer 3b are both formed of a silicone rubber composition of a specific composition filled with powder mica, but these may be the same or different silicone rubber compositions. The silicone rubber composition of That is, in the fire resistant electric wire of the present invention, once the rubber layer 3a is formed on the linear conductor.
After forming the, the rubber layer 3b is further formed thereon to obtain excellent fire resistance.

In the fireproof electric wire of the present invention, the silicone rubber used for forming the rubber layer is preferably HTV.
A millable type silicone rubber such as a so-called "." Can be used, but is not limited to this as long as it can coat the linear conductor with a desired thickness. Examples of such silicone rubbers include polymers such as dimethyl-based, methylvinyl-based, methylphenylvinyl-based, and methylfluoroalkyl-based polymers.

Examples of the vulcanizing agent to be added to the silicone rubber include organic peroxides such as dicumyl peroxide, dibenzoyl peroxide, di-2,4, dichlorobenzoyl peroxide, and t-butyl perbenzoate. Examples of the vulcanizing agent include oxides, but the vulcanizing agent is not limited to organic peroxides. Such a vulcanizing agent can be appropriately selected depending on the type of silicone polymer used and the desired vulcanizing conditions. Further, the blending amount thereof can also be appropriately determined in the same manner, but usually it may be in the range of 0.1 to 3% by weight based on the silicone polymer.

In the rubber layer of the fireproof electric wire of the present invention, the powdered mica used by filling the silicone rubber is as follows:
A particle size (average particle size) of 50 μm or more can be preferably used, but the maximum particle size is 2.5 mm from the viewpoint of uniform dispersion.
It is desirable that it does not exceed. The amount of the powdered mica compounded is 5 per 100 parts by weight of the silicone polymer.
It is desirable that the amount is 250 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 it is more than 250 parts by weight, the withstand voltage characteristics are impaired, so that both are not preferable.

A flame retardant is added to the silicone rubber filled with the powder mica as described above in order to further improve the fire resistance. As such a flame retardant, those which do not generate a halogen compound upon combustion are preferable, and powders of metal hydroxides such as aluminum hydroxide and magnesium hydroxide can be used, but boric acid compounds such as zinc borate are preferable. Particularly preferably used. The amount of the flame retardant compounded is preferably 15 parts by weight or less, particularly about 0.1 to 10 parts by weight, per 100 parts by weight of the silicone polymer.

Further, silicone oil is added to the silicone rubber used in the present invention in order to avoid a decrease in extrusion processability due to an increase in the content of fillers and the like. The amount of such silicone oil blended is preferably 3 to 35 parts by weight per 100 parts by weight of the silicone polymer. If the blending amount is less than this, the smoothness of the refractory layer is lost, and if it exceeds 35 parts by weight, the electrical characteristics at high temperature tend to be unstable, and thus both are not preferable.

Further, to the silicone rubber used in the present invention, stearic acid is added in addition to the silicone oil in order to improve the kneading processability. The amount of such stearic acid added is 0.1 to 2 per 100 parts by weight of the silicone polymer.
It is preferably 5 parts by weight. If the blending amount is less than this, the kneading processability cannot be improved, and even if it exceeds 25 parts by weight, the kneading processability is not improved and the smoothness of the refractory layer is lost, which is not preferable.

The silicone rubber composition as described above is extrusion-coated on a linear conductor composed of a single wire or a stranded wire,
It is guided to a vulcanizer and vulcanized to form a part of the rubber layer.
In the present invention, a rubber layer similar to the above is further laminated and formed on the rubber layer. Only in this way
A fireproof layer composed of a rubber layer having a double structure having excellent performance can be obtained.

A fireproof core obtained by providing a fireproof layer having a structure in which two rubber layers are laminated on a conductor may be formed by bundling a plurality of fireproof cores, if necessary, or The insulating layer is covered with a single core. This insulating layer is formed by extrusion coating an insulative synthetic resin composition using a conventional technique. As the synthetic resin composition, for example, an olefin resin composition such as polyethylene or polypropylene is preferable. Used. In this way, after covering the fireproof core with an insulating layer, if necessary, multiple cores are bundled to form multiple cores, or single cores or multiple cores are arranged in parallel and a protective sheath is provided thereon. The fire resistant electric wire of the present invention can be obtained by extrusion coating such as.

[0021]

Example: Methyl vinyl silicone rubber as a silicone rubber (SR) (TSE250, Toshiba Silicone Co., Ltd.)
2U), TC made by Toshiba Silicone Co. as a vulcanizing agent (CA)
-8, powdered mica with a particle size of 40 μm as an inorganic filler (M
1) and powder mica (M2) having a particle size of 70 μm and a particle size of 40
0 μm powder mica (M3), zinc borate (ZB) as flame retardant, dimethyl silicone oil as silicone oil (SO) (Toshiba Silicone Co., TSF451, viscosity: 1
000 cSt) and stearic acid (SA) were blended and kneaded in accordance with the formulation in Table 1 to prepare silicone rubber compositions for rubber layers. Then, the kneading workability at this time was evaluated by the surface condition of the sheet obtained by the open roll, and a sheet having a smooth surface from the roll was judged to be ◯, and a sheet having a rough surface was judged to be ×.

[0022]

[Table 1]

On the other hand, a stranded copper conductor having a cross-sectional area of 2 mm ² (diameter 1.
8 mm) and each of the above silicone rubber compositions is coated with an extruder at an extrusion temperature of 60 ° C.
A wire core having a diameter of 2.4 mm was obtained by passing through a tubular vulcanizer at 0 ° C. And the extrusion processability at this time, evaluated from the viewpoint of the operating operability of the extruder and the homogeneity of the product, those that can be continuously extrusion-molded easy to set the operating conditions of the extruder, The case where the continuous operation is not easy or the continuous operation is difficult due to the narrow setting range of the operating condition is marked with x.

Next, to these silicone rubber-coated wire cores,
Under the same conditions as above, each silicone rubber composition was overlaid and extrusion-coated to obtain a wire core having a double-structured silicone rubber fireproof layer and a diameter of 2.8 mm. Then, a polyethylene insulating layer was extrusion-coated on this to obtain an insulated electric wire having a diameter of 4.3 mm. After that, a polyethylene sheath was extrusion-coated to obtain fireproof electric wires each having an outer diameter of 7.1 mm.

For comparison, a powder mica layer is laminated on a base material such as a glass fiber cloth or a synthetic resin film to a wire core having a diameter of 2.4 mm obtained by extrusion-coating only one layer with a silicone rubber composition. A wire core having a diameter of 2.8 mm obtained by winding the formed fire-resistant mica sheet having a thickness of about 0.01 to 0.2 mm so as to have a thickness of 0.2 mm, and the silicone rubber described above at one time. A 2.8 mm diameter wire core having a single layer of refractory rubber coating was prepared by thick extrusion coating of the composition. Then, using these wire cores, a polyethylene insulating layer and a polyethylene sheath were sequentially extrusion-coated in the same manner as above to obtain a fireproof electric wire of Comparative Example having an outer diameter of 7.1 mm.

Appearance inspection and flexibility test were performed on the wire core samples obtained by removing the sheath and the insulating layer from each of the fireproof wires thus obtained. Further, the samples cut out from the fireproof wire were tested for insulation properties at room temperature and withstand voltage properties at room temperature, as well as insulation properties at high temperatures and withstand voltage properties at high temperature, and the test results are summarized in Table 1. Are also shown. The test methods and criteria for these tests are as follows.

(1) Appearance The surface of the refractory layer of the core sample was visually inspected, and those having no unevenness and being uniform were evaluated as ◯, and those not having such unevenness were evaluated as x. (2) A flexible core sample was wound around a mandrel having a diameter of 10 mm, and a sample in which no crack was generated was marked with ◯, and a sample with no crack was marked with x.

(3) Vertical 300 mounted vertically on a carriage that can be moved in and out of a room temperature insulating heating furnace
mm, width 300 mm, thickness 10 mm perlite plate,
A fireproof electric wire sample having a length of 1.3 m was horizontally attached and fixed at two positions separated by 20 cm in the center thereof using annealed copper wires each having a diameter of 1.6 mm. Then, at an interval of about 13 mm in the center of the mounting position, both ends of a bundle of two annealed copper wires having a length of 40 cm and a diameter of 1.6 mm are wound, and a fire resistance of 1.3 m is provided at the center of the annealed copper wire. A load equivalent to twice the weight of the wire was applied. Then, a DC voltage of 500 V was applied between the wire core conductor and the fixed wire to measure the insulation resistance value at room temperature, and those having a resistance value of 50 MΩ or more were marked with ◯, and those not having resistance were marked with x.

(4) Normal temperature withstand voltage property Following the above normal temperature insulation property measurement, a commercial AC voltage of 1500 V was applied between the core conductor and the fixed wire, and dielectric breakdown did not occur in 1 minute. , Those that were not were marked with x.

(5) High-Temperature Insulation Property After carrying out the above-mentioned measurement of the room temperature withstand voltage, a truck having a sample of a refractory wire attached was introduced into the heating furnace, and the heating furnace was heated to 840 ° C. in 30 minutes. . In this state, a DC voltage of 500 V was applied between the conductor and the fixed wire, and the insulation resistance value was measured. The one having a resistance value of 0.4 MΩ or more was marked with ◯, and the other one was marked with x.

(6) High temperature withstand voltage Continuing from the above high temperature insulation measurement, a commercial AC voltage of 1500 V was applied between the conductor and the fixed wire, and no dielectric breakdown occurred within 1 minute. Those that are not are marked with x.

Looking at the test results shown in Table 1, the silicone rubber was prepared by coating the silicone rubber composition with a flame retardant, a silicone oil, stearic acid, and powdered mica in a single thick coating. The fire-resistant wire having a single-layer fire-resistant layer obtained by the above does not exhibit sufficient fire-resistant performance, whereas the fire-resistant wire having a two-layer fire-resistant layer obtained by thinly coating in two steps is thin. It can be seen that, like a fire resistant electric wire having a fire resistant layer composed of a rubber layer having a single layer structure and a fire resistant reinforcing layer wound with a mica sheet, it has excellent fire resistant performance.

A silicone rubber composition suitable for forming a fire resistant layer in the fire resistant electric wire of the present invention is 15 parts by weight or less of zinc borate as a flame retardant and 35 parts by weight of silicone oil per 100 parts by weight of silicone rubber. Parts or less and 25 parts by weight or less of stearic acid, and 250 parts by weight or less of powdered mica having a particle size of 50 μm or more are kneading processability, extrusion processability, and insulation and resistance to high temperatures. It can be seen that it is preferable in terms of voltage property.

[0034]

The fire resistant electric wire of the present invention has a two-layer fire resistant layer made of a silicone rubber composition containing a flame retardant, silicone oil and stearic acid and filled with powdered mica. Even with the core wire used, it has advanced insulation characteristics that meet the fire resistance certification standard of the Fire Department Notification No. 7,
In addition to having excellent high temperature withstand voltage characteristics, there is no need to provide a fire resistant reinforcing layer made of mica sheet,
Not only the production efficiency of the electric wire is greatly improved, but also the flexibility of the electric wire is high and the workability is greatly improved.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a structure of a fireproof electric wire according to a conventional technique.

[Explanation of symbols]

1 Fireproof electric wire 2 conductors 3 Fireproof layer 3a rubber layer 3b rubber layer 4 insulating layers 5 sheath

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Claims (2)

(57) [Claims] 1. A fire-resistant layer composed of a double rubber layer formed of silicone rubber containing a flame retardant, silicone oil, and stearic acid and filled with powdered mica on a linear conductor, and an insulating layer composed of a synthetic resin. And the fireproof electric wire
, The first flame retardant is zinc borate and silicone rubber 1
15 parts by weight or less with respect to 00 parts by weight, Steari
25 parts by weight of acid per 100 parts by weight of silicone rubber
Blended below, powder mica having a diameter of 50 μm or more
250 parts by weight for 100 parts by weight of silicone rubber
Compounded below and silicone oil is silicone rubber 1
A fire resistant electric wire characterized by being mixed in an amount of 35 parts by weight or less with respect to 00 parts by weight . 2. A sheath layer is formed on an insulating layer made of synthetic resin.
The fireproof electric wire according to claim 1, which is provided.