JPH0411298Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to the improvement of fireproof electric wires. It is necessary to ensure that the starting devices of various firefighting equipment installed in buildings, electric motors, receivers of automatic fire alarm equipment, guide lights, indicator lights indicating emergency exits, etc. are activated at the same time as a fire occurs. The electric wires used as circuit wiring for each of the above-mentioned facilities are required to be able to withstand high heat even in the event of a fire. In recent years, the basic structure of such fire-resistant wires is to have a fire-resistant layer mainly made of mica on the conductor, an insulating layer such as polyethylene on top of that, and a flame-retardant sheath on the outside. However, conventionally, soft laminated mica has been exclusively used for the fireproof layer of such fire-resistant electric wires, and backing materials such as glass cloth, glass thread, and plastic film are used as a means of coating electric wires with soft laminated mica. It was customary to attach them with an adhesive such as silicone, polyester, or epoxy, and then attach them vertically or wrap them around them. However, when such fire-resistant wires are heated from room temperature to 840 degrees Celsius for 30 minutes in case of a fire, the wires are made of insulators such as polyethylene and vinyl chloride, and the sheath is made of vinyl chloride and flame-retardant polyethylene. is thermally decomposed to generate halogen gas (mainly hydrochloric acid gas), and the above-mentioned adhesive also decomposes in the fireproof layer, creating gaps between the mica layers. As a result of the generated halogen gas (hydrochloric acid gas) penetrating through the spaces between these mica layers, the insulation resistance tends to decrease more than necessary.In particular, unfired hard mica has traditionally been thin and thin. However, recently it has become possible to make thin pieces of this type, which require a relatively small amount of adhesive and reduce the drop in insulation resistance. This idea was made in view of the above-mentioned circumstances, and was created by wrapping mica tape, which is made by bonding fine mica (unfired hard mica) with synthetic resin to a backing material that uses plastic in part or all, as a fireproof layer. By constructing the wire with a longitudinally spliced coating, it was possible to obtain a fire-resistant electric wire that eliminates the above-mentioned defects. That is, since this invention uses unfired mica, when the temperature reaches a high temperature of 500 to 600 degrees Celsius due to a fire, crystallization water is released, the mica swells up, and the mica flakes tend to separate. This is so-called calcined mica, which is heated and fired at approximately 800℃ in advance, and has a temperature of 500 to 600℃.
This works more effectively than if it doesn't swell just because the temperature has reached ℃. Therefore, the unfired hard mica that forms the fireproof layer begins to expand at temperatures above 500°C, and the adhesive that bonds the mica and backing material decomposes and burns out, or the backing material that uses plastic for part or all of it begins to expand. Hydrochloric acid generated by the thermal decomposition of vinyl chloride used as an insulator or sheath, fills the gaps inside the refractory layer that occur when the material is burnt out, and releases crystal water. Gas intrusion can be reduced. To explain this invention with reference to drawings, the fire-resistant electric wire of this invention is made by twisting wire cores with a conductor 1, a fire-resistant layer 2 and an insulating layer 3 with, for example, three intervening strips, and providing an outer sheath 4 as shown in Fig. 1. In particular, the fireproof layer 2 is made of a mica tape bonded with a backing material made partly or entirely of unfired hard mica and plastic, for example, as shown in FIG. Individually or in combination, a sheet made of fine mica flakes made of fired hard mica and a backing material 6 partially or entirely made of plastic such as polyethylene or nylon are attached with an adhesive (e.g. silicone adhesive) The refractory layer 2 is formed by wrapping or longitudinally covering the conductor 1. The types of backing materials include plastic films such as polyethylene and polyester, plastic cloths such as polyester, acrylic, poval, human silk, and cotton, nonwoven fabrics of these plastics, and glass-plastic mixed fabrics, such as nonwoven fabrics made of plastic and glass. Glass thread added vertically, or glass thread added to the warp.
Possible fabrics include cloth using plastic thread as the weft or a mixed fabric of glass thread and plastic thread. Next, an example of this invention will be described. Example ^A tape (A
tape) and a tape (B
Prepare a piece of annealed copper wire with a diameter of 1 mm, with the mica side facing the conductor side, first cover it with one piece of B tape vertically, then wrap one piece of A tape on top of it. The wire was coated with polyethylene insulating coating to a thickness of 0.8 mm, and the wire cores were twisted together with 7-fiber plastic yarn interposed, and then coated with vinyl chloride to a thickness of 1.5 mm to obtain a fire-resistant electric wire of this invention. The results of a comparative test between the electric wire of the above example and the electric wire of the following comparative example (conventional product) are as follows. Comparative example: Soft laminated mica foil with a thickness of approximately 100μ is
ECD450 ^-1/0 with 60 threads/25.4mm, weft with ECD900 ^-1/0
The fireproof electric wire was constructed in the same manner as in the example except that it was made of 30 wires/25.4mm plain-woven glass cloth pasted with a silicone adhesive.

[Table] As can be seen from the above comparative test, this invention uses unfired hard mica as the fireproof layer, so
Since it has better insulation than conventional wires even in high-temperature conditions such as those encountered in fires, it can be used as a fire-resistant wire that functions safely.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the refractory electric wire of this invention, and FIG. 2 is a longitudinal sectional view showing an example of the tape used for the fire-resistant layer of the refractory electric wire of this invention. 1... Conductor, 2... Fireproof layer, 3... Insulating layer, 4
. . . External covering, 5. Paper made from fine mica flakes, 6. Backing material partially or entirely made of plastic.

Claims (1)

[Scope of utility model registration request] In fireproof wires that have a fireproof layer, an insulating layer, and an outer covering on the conductor, the fireproof layer is wrapped with mica tape made by bonding unfired hard mica to a backing material that uses plastic in part or all. A fire-resistant electric wire characterized by being composed of a vertically spliced coating.