JPH0430692B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a halogen-free flame-retardant cable, and in particular, uses so-called halogen-free materials that do not contain halogen elements for the insulator, sheath, and other cable components, and makes the cable structure resistant. The present invention relates to a flame-retardant cable that does not generate toxic gases in the event of a fire, generates little smoke during combustion, and prevents insulators from melting and flowing out. <Conventional technology> Conventional general cables use polyethylene (PE), cross-linked polyethylene (XLPE), etc. as insulators, and multi-core cables use polypropylene, polyester, jute, kraft, etc. as intervening materials. Paper etc. are used. In particular, when making cables flame retardant, the above insulators and sheath parts may be made of polyvinyl chloride, polychloroprene rubber, chlorosulfonated
Use halogen-containing materials such as PE rubber and chlorinated PE, and mix antimony trioxide with them, or use polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate (EEA), ethylene propylene, etc. (EP) A flame retardant resin such as rubber is used, and flame retardance is imparted by mixing a chlorine-based or bromine-based flame retardant with the above-mentioned antimony trioxide. For this reason, with conventional cables of this type,
When heated to high temperatures in the event of a fire, combustion of the sheath itself is suppressed as much as possible in the flame-retardant sheath part, but if the base resin or flame retardant itself contains halogen elements, hydrogen halide gas and halogen A large amount of toxic gas such as gas is generated, and a large amount of smoke is also generated. Therefore, there are problems with safety and the like, making it unsuitable for use in places where high safety is required, such as subway stations, underground malls, ships, and nuclear power plants. Furthermore, since hydrogen kerogen gas is a highly corrosive gas, it can corrode conductors and surrounding metals, which can significantly impair functions such as automatic control. In addition, internal components such as insulators such as polyethylene and cross-linked polyethylene, and intervening materials inside the cable core will melt when exposed to combustion flames, etc.
When it flows as drips and reaches the surface of the cable, it turns into gas due to the high temperature environment and is immediately ignited, causing serious problems such as the cable itself becoming a combustion source and further aggravating the fire. For this reason, for flame-retardant cables that are intended to be more disaster-free, it is necessary to use so-called non-halogen materials that do not contain halogen elements when burning them. As a flame retardant method that does not rely on halogen elements, a method has already been proposed in which a large amount of metal hydrate is added to the base material of rubber or plastic, but the amount of metal hydrate added increases. , there are problems such as deterioration of mechanical properties. Furthermore, in order to improve the heat resistance of insulators, sheaths, etc., it is necessary to crosslink them, but in the case of electron beam crosslinking, if a large amount of metal hydrate is included as mentioned above, the electron beam will not pass through. It may not be possible to use it due to its poor properties and crosslinking efficiency. Furthermore, in the case of organic peroxide crosslinking, a high-temperature, high-pressure atmosphere such as steam or gas is required, which tends to cause deformation of the core inside the cable, making continuous production difficult in the case of multi-core cables. Furthermore, in the case of silane crosslinking, if a large amount of flame retardant is added to the silane grafted resin, the crosslinking reaction will proceed during kneading, making molding difficult and making it impossible to obtain a good appearance. Therefore, when formulating a mixture for cables, it is necessary to consider the balance of various properties of the cable. In other words, there is a certain limit to the improvement of flame retardancy only by adjusting the blend of flame retardants and the like. Therefore, in order to make the cable even more flame-retardant, it is necessary to make the materials themselves such as the insulator and sheath more flame-retardant, and at the same time, from the perspective of the cable structure, it is necessary to prevent molten drip material from reaching the cable surface. It is necessary to have a structure that prevents leakage, does not lose its shape due to collapse or the like even in the event of a fire, and cuts off the supply of oxygen to the inside of the core. In particular, as mentioned above, when the insulator, sheath, etc. must be made of halogen-free rubber or plastic materials to make the cable halogen-free, it is inevitable to use halogen-containing rubbers, plastics, or even halogen-based materials. The flame retardant structure of the cable is also important because the flame retardancy is more likely to deteriorate than when a flame retardant is used. <Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to
In addition to using non-halogen rubber and plastic for the sheath and other constituent materials, we also use a non-halogen element-based flame retardant, and especially for the sheath, we select a blending range that is reasonable for the mixture, and we use silane crosslinking to Heat resistance is also provided, and the cable structure is made into a flame-retardant structure using a frame barrier layer, a barrier protection layer, a carbonized tape layer, etc., making it flame retardant and so-called clean with less halogen gas and smoke generation. The aim is to provide disaster prevention cables that are designed for disaster prevention. <Means for solving the problems> The flame-retardant cable of the present invention basically consists of an insulated wire core with an insulator made of rubber or plastic (excluding those containing halogen elements) on the conductor. or to the outside of the insulated wire core bundle made by twisting these wires, a nonflammable inorganic tape material mainly made of ceramic, or a metal tape material, or an organic material with an oxygen index value of 35 or more is sequentially applied. A flame-retardant tape material, or at least two of these tape materials stacked together by lap wrapping, to protect the above-mentioned insulator and intervening material from heat caused by a fire, etc., and a metal A polyolefin resin mixture consisting of 100-X parts by weight of polyolefin resin (excluding those containing halogen elements) to which 50 to 200 parts by weight of hydrate has been added, and 5 to 40 parts by weight of carbon black or red phosphorus. X parts by weight of a silane-grafted polyolefin resin to which 2/50 parts by weight of a red phosphorus flame retardant has been added (where X is 5 to 5 parts by weight)
80) and a silane-grafted polyolefin resin mixture (excluding those containing halogen elements). Further, if necessary, a carbonized tape layer that is carbonized by heating is provided inside the frame barrier layer, or a barrier protection layer that protects the frame barrier layer is provided outside the carbonized tape layer. The flame-retardant cable of the present invention will be described in more detail with reference to the drawings, as shown in FIGS. 1 to 4. In these cables, 1 is a conductor and 2 is an insulator, forming an insulated wire core 3. 4 is an intervening layer, 5 is a frame barrier layer provided on this cable core,
6 is a carbonized tape layer provided inside the frame barrier layer 5 and carbonized by heating; 7 is a barrier protection layer provided outside the frame barrier layer 5; and 8 is a sheath. The insulator 2 of the cable is made of so-called non-halogen rubber, plastic, etc. that does not contain halogen elements.
For example, PE, crosslinked PE, natural rubber, butyl rubber, silicone rubber, ethylene propylene rubber (EPM),
Ethylene propylene diene elastomer (EPDM), ethylene-vinyl acetate copolymer, ethylene and ethyl acrylate copolymer, ethylene and α-olefin copolymer, ethylene acrylic elastomer, hydrogenated styrene butadiene elastomer, and these It consists of a blend or the like, or something made flame retardant by adding a non-halogen element based flame retardant. For example, when using XLPE (crosslinked polyethylene) for this insulator 2,
To crosslink polyethylene, organic peroxides such as DCP (dicumyl peroxide), 2,5-
Dimethyl-2,5-di(t-butylperoxine)
Chemical crosslinking methods such as a method using hexane or the so-called silane crosslinking method using a silane coupling agent such as vinyl alkoxysilane, or an electron beam crosslinking method can be employed. The above-mentioned intervention material 4 is jute, paper, non-moisture-absorbing treated paper, flame-retardant treated paper, flame-retardant polypropylene (PP),
Made of PP yarn, polyethylene terephthalate film, etc. The frame barrier layer 5 is a layer for protecting the insulator 2, the interposer 4, etc. of the wire core bundle from fire in the event of a fire, and is made of a nonflammable inorganic tape material mainly made of ceramic, or a metal tape material. ,
Alternatively, it is a flame retardant tape material mainly consisting of an organic material having an oxygen index value of 35 or more, or a superposition of at least two types of tape materials among these. Examples of inorganic tape materials include mica mylar tape, mica glass tape, mica paper mixed tape, asbestos tape, mica paper laminated tape, silicone or alkylene varnished glass tape, alumina/silica fused thread-proofing tape (kao wool, ceramic fiber), etc. Such)
and glass fiber composites, alumina, and glass laminate tapes. Examples of metal tape materials include copper (Cu), iron (Fe), stainless steel (SUS), brass, aluminum (Ai),
Examples include tapes such as aluminum and Mylar laminated tape. Further, flame-retardant tapes mainly made of organic materials with an oxygen index value of 35 or higher include, for example, polyetheretherketone (PEEK), polyimide resin, flame-retardant rubberized cloth tape, polyethersulfone, polyetherimide polysulfone, polycarbonate, Examples include phenolic resin and aromatic polyester. Furthermore, the above inorganic tape,
It is also possible to use a combination of two or more metal tapes and tapes mainly made of organic materials with an oxygen index value of 35 or more. As for the actual coating method, for example, in the case of inorganic tape material or organic flame retardant tape material, 1 to 5 pieces of tape with a thickness of 0.05 to 0.2 mm are wound in a 1/5 to 1/2 wrap. , or thickness 0.03~ for metal tape material
It is formed by winding 1 to 3 pieces of one or two types of tape in a 1/5 to 1/2 lap of 0.2 mm thick. The carbonized tape layer 6 is made of kraft paper, acrylic fiber cloth, human silk cloth, natural cellulose fiber, or a cloth tape obtained by impregnating these with silicone varnish, archite varnish, etc., and is applied by lap winding in the same manner as the frame barrier layer. Note that this carbonized tape layer 6 is omitted in the frames shown in FIGS. 3 and 4. The barrier protection layer 7 that protects the frame barrier layer 5 is formed by winding a tape made of, for example, inexpensive asbestos, glass, ceramic fiber, or a composite thereof. In addition, Figure 2,
This layer is omitted in FIG. On the other hand, the sheath 8 is made of halogen-free polyolefin resin such as PE, ethylene, etc.
α-olefin copolymers, EVA, EEA, ethylene acrylic elastomers, ethylene propylene copolymers, ethylene propylene diene elastomers, etc., or at least two of these.
Metal hydrates, such as aluminum oxide hydrate (AI ₂
O ₃ , 3H ₂ O), hydrates of magnesium oxide (MgO, H ₂ O), basic magnesium and calcium hydroxide, or these metal hydrates with fatty acid silane coupling agents, phosphate esters, etc. A silane prepared by mixing a silane-grafted polyolefin resin and carbon black or a red phosphorus flame retardant with a red phosphorus component of 2 to 50% by weight to a polyolefin resin mixture that has been surface-treated by Formed from a grafted polyolefin resin mixture (excluding those containing halogen elements). Here, the blending amount is 50 to 200 parts by weight of the metal hydrate per 100-X parts by weight of the polyolefin resin, and X parts by weight of the silane-grafted polyolefin resin (however,
X is 5 to 40 parts by weight of carbon black or 2 to 50 parts by weight of the above-mentioned red phosphorus flame retardant.
The silane-grafted polyolefin-based resin mixture and the metal hydrate polyolefin-based resin mixture have resin components, that is, a polyolefin resin and a silane-grafted polyolefin resin.
Mix to make 100 parts by weight. That is, 20 to 95 parts by weight of polyolefin resin, 50 to 200 parts by weight of metal hydrate.
The reason for the parts by weight is that if the polyolefin resin is less than 20 parts by weight, extrusion processability is poor, if it is more than 95 parts by weight, almost no degree of crosslinking can be obtained, and if the metal hydrate is less than 50 parts by weight, This is because sufficient flame retardancy cannot be obtained, and if it exceeds 200 parts by weight, processability deteriorates, so an optimal range with a good balance between flame retardancy, processability, and crosslinking was selected. Also, 5 to 80 parts by weight of silane grafted polyolefin resin, 5 to 40 parts by weight of carbon black, and 2 to 50 parts by weight of red phosphorus flame retardant.
The reason for using parts by weight is that if the amount of the silane-grafted polyolefin resin is too large, processability will be poor, and if it is too small, the desired degree of crosslinking cannot be obtained. The reason for adding a predetermined amount of carbon black and red phosphorus flame retardant to the silane-grafted polyolefin resin is to keep the viscosity at the same level as the aforementioned polyolefin resin mixture. Here, in the event of a fire, metal hydrates suppress temperature rise through a mechanism involving an endothermic reaction that releases crystal water, carbon black itself remains carbonized, and red phosphorus flame retardants do so due to their dehydration reaction. , has the effect of dehydrating polyolefin resin and promoting carbonization of the resin. <Function> In this way, by using flame retardants and base rubbers and plastics that do not contain halogen elements, they are flame retardant, do not generate toxic gases, are highly safe, and are resistant to corrosion. There is no fear. In addition, since the frame barrier layer 5 has a structure made of an inorganic tape material, a metal tape material, an organic flame-retardant tape material, or a combination thereof, synergistic effects such as heat resistance, flame retardance, and airtightness of these tapes can be obtained. Therefore, the layer 5 itself has good heat resistance and is not easily damaged even in the event of a fire, which effectively cuts off heat transfer and air supply to the inside of the cable core. The inside of the core is well protected. Further, the carbonized tape layer 6 immediately below this layer 5 is also carbonized extremely well. Therefore, due to the temperature rise of the cable,
Even if the insulator 2 inside the core melts, the carbonized tape layer 6 forms a kind of unglazed wall due to the carbonization.
Together with the interaction with the resin, it almost completely prevents the resin from seeping out. Furthermore, the barrier protection layer 7 provided on the frame barrier layer 5 strongly protects and reinforces the frame barrier layer 5 against mechanical external forces, etc., and also has low heat transfer properties due to the material, so it can prevent fires. In such cases, thermal protection of the barrier layer 5 serves to suppress the rise in temperature of the sheath 8. Further, since the sheath 8 is cross-linked with silane, the heat resistance and cold resistance of the sheath 8 itself are improved. Furthermore, since carbon black and, if necessary, a red phosphorus flame retardant are mixed into the sheath, carbonization occurs smoothly in the event of a fire, and the inside of the core is protected. Note that other additives such as anti-aging agents, lubricants, coupling agents for treating fillers, catalysts for promoting crosslinking, etc. may be added to the insulator 2, the interposer 4, and the sheath 8, if necessary. Furthermore, although the above description has been made regarding multi-core cables, the present invention is of course applicable to single-core cables as well. <Example> Next, each example (No.
1 to 24) are shown in Table 1. In addition, comparative examples (Nos. 1 to 4) are shown for comparison. Further, in the silane crosslinked sheath of the present invention, Examples (Nos. 25 to 34) were prepared with various formulations as shown in Table 2. Regarding this, comparative examples (Nos. 5 to 10) were also produced.

【table】

【table】

【table】

[Table] Processed products, ＊＊＊＊ Untreated products.

【table】

[Table] Rippin.
Each example (No. 1 to 2) in Table 1 and Table 2 above
34), the cable according to the present invention generates little smoke and does not generate toxic and corrosive gases such as hydrogen chloride gas. Moreover, it is also found that it has sufficient flame retardancy. In addition, the properties of the sheath are also excellent. On the other hand, comparative examples (No. 1 to
10) Conventional cables have poor flame retardancy, generate a lot of smoke, and when hydrogen chloride gas is generated, the concentration is dangerous to the human body.
The concentration was sufficient to corrode the contacts of surrounding electrical equipment. Furthermore, the sheath also had poor extrudability and was unsatisfactory. <Effects of the Invention> According to the present invention, as is clear from the above description, non-halogen rubber or brass is used for the insulator, sheath, and other constituent materials, and the sheath is cross-linked with silane. , and in terms of cable structure, outside the insulated wire core or outside the insulated wire core bundle made by twisting these wires together,
A non-flammable inorganic tape material mainly made of ceramic, etc., a metal tape material, a flame-retardant tape material mainly made of an organic material with an oxygen index value of 35 or more, or a combination of at least two types of tape materials. If necessary, a barrier protection layer made of asbestos, glass, etc. tape is provided on the outside of this layer, or a carbonized tape layer that is carbonized by heating is provided on the inside of the frame barrier layer. Therefore, it is possible to provide a flame-retardant cable that has excellent flame retardancy and heat resistance, does not generate toxic gases, and is clean with a small amount of smoke when burned. In particular, because it uses silane crosslinking, there is no need for large-scale crosslinking equipment, making it highly economical.
Further, by employing the flame barrier layer, the burden of flame retardancy on the sheath is reduced, so that good processability with excellent mechanical properties can be obtained. Further, by protecting the sheath, the frame barrier layer, etc., it is possible to use an insulator that emphasizes its original electrical properties.

[Brief explanation of drawings]

1 to 4 are longitudinal cross-sectional views showing each embodiment of the flame-retardant cable according to the present invention. DESCRIPTION OF SYMBOLS 1... Conductor, 2... Insulator, 5... Frame barrier layer, 6... Carbonized tape layer, 7... Barrier protection layer, 8... Sheath.

Claims (1)

[Scope of Claims] 1. Outside an insulated wire core with an insulator of rubber or plastic (excluding those containing halogen elements) applied to a conductor, or outside an insulated wire core made by twisting these materials together. On the other hand, non-flammable inorganic tape materials mainly made of ceramics, metal tape materials, flame-retardant tape materials mainly made of organic materials with an oxygen index value of 35 or more, or at least two types of tape materials among these. A flame barrier layer formed by overlapping the above insulators and the intervening material from heating in the event of a fire, etc., and a polyolefin resin 100-100 containing 50 to 200 parts by weight of a metal hydrate. A polyolefin resin mixture consisting of X parts by weight (excluding those containing halogen elements) and 5 to 40 parts by weight of carbon black or 2 to 50 parts by weight of red phosphorus component.
Parts by weight of silane-grafted polyolefin resin added with parts by weight of red phosphorus flame retardant (However,
1. A flame-retardant cable comprising a silane crosslinked sheath made of a mixture of a silane-grafted polyolefin resin mixture (excluding those containing a halogen element) and a silane-grafted polyolefin resin mixture (where X is 5 to 80). 2. The flame-retardant cable according to claim 1, wherein 5 to 40 parts by weight of carbon black is mixed into the polyolefin resin mixture. 3. The flame retardant according to claim 1 or 2, wherein a red phosphorus flame retardant containing 2 to 50 parts by weight of red phosphorus is mixed into the polyolefin resin mixture. sex cable. 4 A carbonized tape layer that is carbonized by heating is provided inside the frame barrier layer, so that in the event of a fire, etc., the carbonized layer is formed to prevent the melted insulators and intervening material from flowing out. A flame-retardant cable according to claim 1, 2, or 2. 5 Claims characterized in that a barrier protection layer for protecting the frame barrier layer is provided on the outside of the frame barrier layer to mechanically or thermally protect the frame barrier layer in the event of a fire, etc. The flame-retardant cable according to item 1, 2, 3, or 4.