JP3821425B2 - Refractory wire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refractory electric wire having required fire resistance performance and electrical characteristics against high heat and flame in an emergency such as a fire.
[0002]
[Prior art]
The wire / cable, which is a general term for fireproof wires specified in the standards of the Fire Department Notification No. 10 of 1997, satisfies the specified fireproof performance, and has the structure specified in the Electrical Appliance and Material Control Law and the Electrical Equipment Technical Standards Act. It is said that it satisfies the dimensions and electrical / mechanical characteristics.
[0003]
FIG. 3 is a cross-sectional view schematically showing a part of a conventional fireproof electric wire described in JP-A-11-345524. In this case, the refractory wire 1 is provided with a refractory layer 3 and an insulator 4 on a conductor 2 such as a stranded copper wire to form an insulated core 5, and a sheath 6 is provided on the insulated core 5. .
[0004]
The refractory layer 3 is formed by winding a plurality of glass mica tapes on the conductor 2 (wrapping winding) or wrapping vertically. Glass mica tape is made by using inorganic glass tape as a base material (lining material) and affixing soft laminated mica foil on one side. The laminated mica foil faces the conductor 2 and multiple sheets are stacked. Winding. The insulator 4 is typically formed by coating an ethylene resin composition such as polyethylene or a vinyl chloride resin onto the refractory layer 3. A sheath 6 is formed by coating a polyolefin resin or a vinyl chloride resin on the insulating core 5 formed as described above.
[0005]
[Problems to be solved by the invention]
By the way, there are the following problems in common with the fireproof wire 1 described in the publication shown in FIG. 3 and other conventional fireproof wires.
[0006]
First, after forming a refractory layer 3 by wrapping a plurality of glass mica tapes on the conductor 2 and extruding a molten resin such as polyethylene onto the refractory layer 3 when the insulator 4 is molded, That is, the lower refractory layer 3 is deformed. If the refractory layer 3 is deformed, it will be unsatisfactory due to the influence of the prescribed electrical characteristics. In order to prevent the deformation of the refractory layer 3 due to such resin pressure, it is conceivable to wind the glass mica tape tightly to increase the tape tension. However, when the tension of the glass mica tape is increased, the glass fiber at the end of the tape flutters up and becomes “blemish” indicated by reference numeral 3a in FIG. 3 and enters the inside of the insulator 4, which also causes a decrease in electrical characteristics. Become.
[0007]
One is that during the molding of the insulator 4 by extruding polyethylene molten resin onto the refractory layer 3, the gas present in the glass mica tape of the refractory layer 3 expands due to the heat of the molten resin, and the insulator 4. It is an effect of affecting electrical characteristics such as insulation by entering inside and remaining as “voids”. As a measure for preventing the generation of voids, generally, immediately after the polyethylene molten resin is extruded, a cooling process is performed in which the insulator 4 is formed by solidification by water cooling. However, if the thickness dimension of the insulator 4 exceeds 2.5 mm, it takes a considerable time for the cooling to be completed throughout the thickness of the insulator 4. Therefore, there is a problem that generation of voids cannot be sufficiently suppressed.
[0008]
Furthermore, since the fireproof layer 3 made of glass mica tape is pressed and wound with polyester tape (not shown) from the top as in the conventional example of FIG. 3 in particular, the stripping process of the wire terminal is performed at the wiring site. The work to peel off the polyester tape during the work to be performed increases.
[0009]
Therefore, the object of the present invention is to effectively suppress the generation of voids caused by the expansion of the gas in the glass mica tape forming the refractory layer and the gas in the refractory layer and entering the insulator. An object of the present invention is to provide a refractory electric wire that satisfies the required fire resistance performance and electrical characteristics and eliminates the labor of stripping the tape that holds and winds the glass mica tape during the stripping process.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a refractory wire according to claim 1 according to the present invention includes a conductor 11, a refractory layer 12 provided by winding a glass mica tape on the conductor 11, and an extrusion molding on the refractory layer 12. An insulating wire core 15 is formed by the insulator 13 provided as described above, and a laminated tape composed of an inner layer and an outer layer having two different melting points is different in melting point from the insulator 13. An inner layer faces the fireproof layer 12, and an outer layer having a low melting point substantially the same as or lower than that of the insulator 13 faces the insulator 13, and the laminate tape shielding layer 14 is wound on the fireproof layer 12. It is characterized by being formed.
[0011]
With the above configuration, the laminate tape shielding layer 14 provided by being wound around the refractory layer 12 functions as follows.
(1) When the laminate tape is wrapped with a suitable tape tension on the fireproof layer 12 of the glass mica tape, the fireproof layer 12 is not deformed by the resin pressure during extrusion molding of the insulator 13, and the fireproof is expanded by resin heat. The pressure of the gas in the layer 12 does not lift the tape itself. As a result, it is possible to prevent the glass fiber chip of the fireproof layer 12 from entering the insulator 13, and to suppress the expanded gas from entering the insulator 13 to generate voids, thereby suppressing the deterioration of electrical characteristics. It is done. On the other hand, when the laminated tape is wound vertically, the tape tension is insufficient, so that the effect like the wrap winding cannot be expected.
(2) Since the melting point of the outer layer of the laminate tape is substantially the same as or lower than that of the facing insulator 13, the outer layer is melted by the extrusion resin heat of the insulator 13 and integrated with the inner surface of the insulator 13. To fuse. At that time, the melted outer layer is fused and sealed by wrapping, and the inner layer having a melting point higher than that of the insulator 13 remains without being melted. That is, the entire laminate tape shielding layer 14 has a cylindrical shape as if the outer layer is melted and coated on the inner layer, and the gas in the refractory layer 12 expands and tries to enter the insulator 13. Thus, the cylindrical laminated tape shielding layer 14 is integrally fused to the inside of the insulator 13 to prevent it from becoming a barrier, and the generation of voids in the insulator 13 can be effectively suppressed.
(3) As in (2) above, the laminate tape shielding layer 14 is formed into a cylindrical shape and integrated into the inside of the insulator 13 to become a barrier, so that during the work of performing stripping processing of the wire terminal at the wiring site, When the insulator 13 is peeled, the laminate tape shielding layer 14 is also peeled at the same time. Therefore, it is not necessary to peel the laminate tape shielding layer 14 again after the insulator 13 is peeled off, thereby saving labor. That is, since the labor of peeling off like a conventional press-wound tape can be saved, the work efficiency is improved.
[0012]
Moreover, the fireproof electric wire according to claim 2 is characterized in that the laminate tape shielding layer 14 has a polyester layer as an inner layer and a polyethylene layer as an outer layer.
[0013]
In this case, as a specific example of the material of the inner layer and the outer layer constituting the laminate tape shielding layer 14 according to claim 1, the inner layer is made of polyester higher than the melting point of the insulator 13, and the outer layer is substantially equal to the melting point of the insulator 13. The same or less polyethylene is used. The material of the insulator 13 is generally made of an ethylene resin composition. Therefore, the outer layer polyethylene of the same material is melted by the resin heat during the extrusion molding of the insulator 13 and is integrally fused to the inner surface of the insulator 13. Thereby, the laminated tape shielding layer 14 is formed into a cylindrical shape in which the outer polyethylene layer is coated on the inner polyester layer.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a refractory wire according to the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a cross-sectional view showing a refractory wire 10 according to the present embodiment. A refractory layer 12 is formed on a conductor 11 such as a copper stranded wire. As described in the conventional example of FIG. 3, this refractory layer 12 is made of a soft laminated mica foil with an inorganic glass tape as a backing material. And a plurality of such glass mica tapes are preferably wrapped and overlapped, preferably with the laminated mica foil surface facing the conductor 11 side.
[0016]
Further, as shown in the enlarged partial sectional view of FIG. 2, the laminate tape shielding layer 14 is provided by winding the laminate tape as the gist of the present invention around the surface which is the outermost layer of the glass mica tape forming the fireproof layer 12. ing. This laminate tape shielding layer 14 is made by laminating polyester and polyethylene materials filmed or the like on the front and back surfaces to form a laminate tape. The polyester layer is the inner layer and faces the fireproof layer 12, and the polyethylene layer is the outer layer. Then, it is formed by wrapping on the refractory layer 12 so as to face the insulator 13 provided in the next step.
[0017]
Insulator 13 is extruded and coated on the outer polyethylene layer of laminate tape shielding layer 14. Generally, polyethylene, which is an ethylene-based resin composition, is frequently used as the material of the insulator 13, and in this example, a polyethylene resin is used as the insulator 13, and a polyethylene layer of the same material having substantially the same or lower melting point is used. Numerous good results to be described later can be obtained by using the outer layer of the laminate tape shielding layer 14.
[0018]
As described above, the insulation core 15 is formed by providing the fireproof layer 12, the laminate tape shielding layer 14, and the insulator 13 on the conductor 11. As shown in FIGS. 1 and 2, the present embodiment shows a single core refractory wire 10 in which a plastic sheath 16 such as a polyolefin resin is extruded and coated on an insulating wire core 15. On the other hand, a plurality of the insulating wire cores 15 are bundled by being twisted together, filled with inclusions between the plurality of wire cores, wound with pressing tape, and the sheath 16 is extruded thereon. Thus, a fireproof cable can be obtained.
[0019]
In the refractory electric wire 10 of the present embodiment, the insulated wire core 15 is provided and operates as follows.
[0020]
As the refractory layer 12 provided on the conductor 11, a plurality of glass mica tapes can be wrapped tightly and the tape tension can be increased. When the insulator 13 is provided on the refractory layer 12 through the laminate tape shielding layer 14, the refractory layer 12 tends to be deformed by the resin pressure during the extrusion molding of the polyethylene molten resin, but the refractory layer 12 is tightly wound. Therefore, even if the resin pressure of the insulator 13 works together with the laminate tape shielding layer 14 interposed, it does not deform. By preventing the refractory layer 12 from being deformed, the prescribed electrical characteristics can be satisfied.
[0021]
By the way, when the refractory layer 12 is tightly wound, it is effective for preventing deformation. On the other hand, when the refractory layer 12 is tightly wound and the tape tension is increased, the glass fiber may be generated from the end surface of the glass mica tape. Even if glass fiber cracks are generated from the refractory layer 12, the laminate tape shielding layer 14 suppresses the glass fiber cracks from entering the insulator 13, so that the Deterioration of electrical characteristics can be prevented by preventing invasion.
[0022]
As described above, the laminate tape shielding layer 14 formed by winding the laminate tape on the fireproof layer 12 has sufficient tape tension by wrapping. At the same time, even if the gas in the refractory layer 12 expands due to the resin heat during the extrusion of the insulator 13, the tape itself does not rise. Thereby, it can suppress that the expanded gas penetrate | invades into the insulator 13 and becomes a void.
[0023]
When the insulator 13 is provided by extruding a polyethylene molten resin on the laminate tape shielding layer 14, the laminate tape shielding layer 14 acts as follows. During the extrusion of the molten polyethylene resin, the polyethylene layer which is the outer layer of the laminate tape shielding layer 14 is melted by the resin heat and united with the insulator 13. It is as if the laminated tape shielding layer 14 was coated with an outer polyethylene layer on the inner polyester layer. Also, at that time, the outer outer polyethylene layer flows into the wrap-wrapped tape winding and is sealed by sealing, and the outer polyethylene layer is coated without gaps over the entire inner polyester layer that does not melt. It becomes. The cylindrical laminated tape shielding layer 14 is interposed between the refractory layer 12 and the insulator 13.
[0024]
Thus, while the polyethylene molten resin is extruded and the insulator 13 is covered and molded, the gas in the refractory layer 12 expands due to the heat of the resin, and it goes out of the layer and enters the insulator 13 to generate voids. The laminate tape shielding layer 14 having the cylindrical shape as described above serves as a barrier to prevent it.
[0025]
On the other hand, in the refractory electric wire 10 of the present embodiment, the following effects are brought about at the time of construction work such as stripping of the electric wire terminal at the wiring site. In order to make the conductor 11 exposed in preparation for electrical connection, the outermost sheath 16 to the innermost refractory layer 12 are stripped in order. At the time of such stepping work, since the laminate tape shielding layer 14 adheres to the inside of the insulator 13 when it is peeled off, the laminate tape shielding layer 14 is peeled off again after the insulator 13 is peeled off. Can be omitted. This is because during extrusion molding of the insulator 13, the polyethylene layer of the outer layer of the laminate tape shielding layer 14 is fused by the heat of the molten resin so as to form a cylindrical shape and be integrated with the insulator 13.
[0026]
In the refractory wire 10 of the present embodiment, an example in which polyethylene and polyester are used as the material of the inner and outer layers forming the laminate tape shielding layer 14 is shown, but the technical idea according to the present invention is satisfied. For example, other materials can be used. That is, the outer layer is made of a material having a melting point substantially the same as or lower than that of the insulator 13, and the outer layer needs to be melted and integrated by the resin heat during the extrusion of the insulator 13. Further, it is desirable that the inner layer is made of a material having a melting point higher than that of the insulator 13 and remains without being melted even by resin heat during the extrusion molding of the insulator 13.
[0027]
【The invention's effect】
As described above, the refractory wire according to claim 1 of the present invention has the following effects.
(1) When a laminate tape is wrapped with a suitable tape tension on a refractory layer of glass mica tape, the refractory layer is not deformed by the resin pressure during extrusion molding of the insulator, and the refractory layer expanded by resin heat The tape itself is not lifted by the gas pressure. As a result, it is possible to prevent invasion of the glass fiber in the refractory layer into the insulator, and it is possible to suppress the expanded gas from entering the insulator and generating voids, thereby suppressing deterioration in electrical characteristics. On the other hand, when the laminated tape is wound vertically, the tape tension is insufficient, so that the effect like the wrap winding cannot be expected.
(2) Since the melting point of the outer layer of the laminate tape is substantially the same as or lower than that of the facing insulator, the outer layer is melted by the extrusion resin heat of the insulator and is integrally fused to the inner surface of the insulator. To do. At that time, the melted outer layer is fused and sealed with a tape winding by wrapping, and the inner layer having a melting point higher than that of the insulator remains without being melted, so that the entire laminated tape shielding layer is as if the outer layer is placed on the inner layer. The tube is melted and coated, and the gas in the refractory layer expands and attempts to enter the insulator. The cylindrical laminated tape shielding layer is fused together inside the insulator. Therefore, it becomes a barrier and prevents it, and the generation of voids in the insulator can be effectively suppressed.
(3) The laminate tape shielding layer is formed into a cylindrical shape and integrated inside the insulator to become a barrier, so that when stripping the insulator at the wiring site, the insulator is peeled off and laminated together with it. The tape shielding layer is also peeled off at the same time, eliminating the need to peel off the laminated tape shielding layer after the insulation has been peeled off, saving the work and saving the trouble of peeling off like a conventional press-wound tape. So work efficiency is improved.
[0028]
In addition, as a specific example of the material of the inner layer and the outer layer constituting the laminated tape shielding layer, the refractory electric wire according to claim 2 uses a polyester having a higher melting point than the insulator for the inner layer, and the melting point of the insulator is substantially equal to the melting point of the insulator. The same or less polyethylene is used. Since the insulator is generally made of an ethylene-based resin composition, when an insulator of such a material is extruded, the outer layer polyethylene of the laminate tape shielding layer of the same material is melted together by the resin heat, and is formed on the inner surface of the insulator. Fusing together. That is, the laminated tape shielding layer has a cylindrical shape in which an outer polyethylene layer is coated on an inner polyester layer, and the effect described in claim 1 becomes more remarkable.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a refractory wire according to the present invention.
FIG. 2 is an enlarged cross-sectional view showing a main part of the present embodiment.
FIG. 3 is a cross-sectional view showing a conventional refractory electric wire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Refractory wire 11 Conductor 12 Refractory layer 13 Insulator 14 Laminate tape shielding layer 15 Insulated wire core 16 Sheath

Claims (2)

A refractory wire in which an insulation core is formed by a conductor, a refractory layer provided by wrapping a glass mica tape on the conductor, and an insulator provided by extrusion molding on the refractory layer,
A laminated tape consisting of two layers, an inner layer and an outer layer, having different melting points, has an inner layer having a melting point higher than that of the insulator facing the refractory layer, and an outer layer having a melting point substantially equal to or lower than that of the insulator. A fireproof electric wire characterized in that a laminate tape shielding layer is formed by facing a body and winding on the fireproof layer. The fireproof electric wire according to claim 1, wherein the laminated tape shielding layer has a polyester layer as an inner layer and a polyethylene layer as an outer layer.

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