JPS639955Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Technical Field of the Invention) The present invention relates to improvements in flame-retardant cables. (Technical background of the invention and its problems) Conventionally, when improving the flame retardance of cables, organic halogen flame retardants and antimony trioxide were mixed with halogen-containing polymers such as polyvinyl chloride and polychloroprene, and polyolefins. is used as a sheath. However, there is a problem in that the sheath decomposes during combustion and generates hydrogen halide gas, which has an adverse effect on the human body and equipment. Recently, there has been a desire to realize flame-retardant cables that do not contain halogens, and attempts have generally been made to fill polyolefin with a large amount of hydrated alumina as a sheath material. Various issues can be raised. (1) Mechanical strength decreases when filled in large quantities. (2) Electrical characteristics will deteriorate if filled in large quantities.
(It also absorbs moisture easily, making it unsuitable for use in high temperature and high humidity environments.) (3) Processability and crosslinking properties deteriorate. (4) If the amount added is small, flame retardancy will not improve. (Purpose of the invention) The present invention was devised in view of the above situation, and the purpose is to provide a flame-retardant cable that can improve flame retardancy without impairing the physical properties of the insulation and sheath material. . (Summary of the invention) The flame-retardant cable of the invention has a tape layer mainly composed of an inorganic material on an insulated wire core, and protection made by adding 100 to 300 parts by weight of metal oxide hydrate to 100 parts by weight of polyolefin. The above objective is achieved by sequentially providing a tape layer containing an inorganic material as a main component, and further coating the outside with a flame-retardant sheath layer that does not contain halogen. The insulator used in the present invention may be a commonly used insulating polyolefin such as polyethylene or crosslinked polyethylene, or a polyolefin prepared by adding an appropriate amount of a metal hydrate using a Banbury mixer or the like. Further, as the restraining tape, tapes mainly composed of inorganic materials that do not deform even when exposed to flame, such as glass tape, ceramic tape, copper tape, etc. can be used. Furthermore, the protective layer may be made of polyolefin such as ethylene/propylene rubber or ethylene/vinyl acetate copolymer.
Add 100 to 300 parts by weight of a metal hydrate such as hydrated alumina or magnesium hydroxide to 100 parts by weight, mix with a Banbury mixer or mixing roll, and wrap the mixture into a tape or extrusion coating. can do. The reason why the amount of metal hydrate was defined as 100 to 300 parts by weight is that if it is less than 100 parts by weight, the flame retardance will be insufficient, and if it exceeds 300 parts by weight, the mechanical properties and extrusion processability will be poor. be. In addition, a flame-retardant sheath that does not contain halogen can be obtained by adding at least 100 parts by weight of a metal hydrate to 100 parts by weight of a polyolefin such as polyethylene, ethylene/propylene copolymer, or ethylene/vinyl acetate copolymer. A composition with an index of 25 or higher is used. (Embodiment of the invention) Hereinafter, an embodiment of the flame-retardant cable of the invention will be described with reference to the drawings. The figure shows a cross-sectional view of a 7-strand cable, in which the outer periphery of each conductor 1 is coated with an insulator 2, and then the insulator 2
They are twisted together with an interposer 3 inserted between them, and an internal restraining tape 4, a protective layer 5, an external restraining tape 4', and a non-halogen flame-retardant sheath 6 are sequentially provided on the outer periphery thereof. For cables with the above structure, the nominal cross-sectional area
A 2.0mm ² conductor is coated with an insulator with a coating thickness of 0.8mm,
Seven strands of these are twisted together with an intervening material, and when an internal restraining tape is used, a glass tape is wound around the outer periphery of the stranded wires, and a protective layer is extruded and coated on this outer periphery, and when an external restraining tape is used, a glass tape is wrapped around the strands. The cable was wound, and a sheath was extruded around the outer periphery of the cable to obtain a specified flame-retardant cable. The compositions of these insulators, tapes, protective layers, and sheaths are shown in the table. Next, five test samples were taken from arbitrary locations on the insulator, the intervening material, and the sheath, and their oxygen index and mechanical strength were examined, and the results are also shown in the table. Furthermore, a flame retardant test is performed on the wire sample, but the flame retardant test here is
IE ³ std383VFT is used, and in this test, a specified number of wire samples are laid vertically on a metal tray, twisted and fired vertically, and the wire samples are placed on the top of the tray during the test period (20 minutes) or after the burner is extinguished. Passing the test is determined by the fact that the fire does not spread up to 1.8m.

【table】

[Table] (Effects of the invention) As described above, the flame-retardant cable of the invention has a structure in which a protective layer filled with a large amount of metal hydrate is sandwiched between the insulator and the sheath using inner and outer restraining tapes. It has good flame retardancy, does not impair the extrusion processability of insulation and sheathing, and is a non-halogen type, so it has the advantage of not generating gas that can adversely affect the human body or equipment when burned.

[Brief explanation of the drawing]

The figure is a diagram showing a cross-sectional view of a flame-retardant cable according to the present invention. 1...conductor, 2...insulator, 3...intervening, 4,4'...
Pressure tape, 5...protective layer, 6...non-halogen flame retardant sheath.

Claims (1)

[Scope of utility model registration request] A tape layer mainly composed of inorganic material on the insulated wire core,
A protective layer made by adding 100 to 300 parts by weight of a metal oxide hydrate to 100 parts by weight of polyolefin and a tape layer mainly composed of an inorganic material are sequentially provided, and a flame-retardant sheath that does not contain halogen is provided on the outside. A flame-retardant cable characterized by being coated with a layer.