JPS6338804B2 - - Google Patents

Description

[Detailed description of the invention]

Generally, rubber and plastic wires and cables are coated with flammable materials such as polyethylene, cross-linked polyethylene, and soft polyvinyl chloride, and if these wires and cables catch fire, the wires and cables will spread, causing significant fire damage. There is a fear.
In order to prevent this, a method of applying a fire spread preventive agent to the electric wire cable is widely adopted. However, if the cable to be treated to prevent the spread of fire is a thick one for high voltage or ultra-high voltage, it is better to wrap it with flame-retardant tape rather than applying a fire-spread preventive agent because it will not be installed in close proximity. is easy to enforce. Traditionally, tape with an adhesive layer or self-adhesive tape has been used in this method, but in the case of tape with an adhesive layer, the flame retardance may be reduced due to the adhesive layer, or the tape may not be suitable for use. There is a problem that if it gets stuck, it cannot be removed easily, and in the case of self-adhesive tape,
Chlorine-based rubber is often used unvulcanized, and the self-bonding properties of the tape change significantly over time, resulting in a loss of self-bonding properties during storage, and the unvulcanized tape may lose its strength. I had a problem with it deforming without any problems. The present invention has been made in consideration of the above points, and is made by blending a chlorine-based rubbery polymer with an ethylene-vinyl acetate copolymer, and adding a vulcanizing agent for the chlorine-based rubbery polymer to produce a chlorine-based rubbery polymer. By vulcanization, it is possible to provide a self-bonding flame retardant tape which has no deterioration in flame retardancy, is strong, and shows no change in self-bonding properties over time. The tape of the present invention comprises a mixture of a chlorinated rubbery polymer and an ethylene vinyl acetate copolymer, an inorganic filler,
It consists of rubber vulcanizing agents such as metal oxides and sulfur compounds, organic flame retardants, anti-aging agents, etc. When based on polymers that do not contain halogens such as chlorine,
In order to impart flame retardancy, it is necessary to incorporate a large amount of flame retardant, which significantly reduces the strength of the tape, so it is necessary to use a chlorine-based polymer. Furthermore, in order to sufficiently follow the bending of the cable and to make it easier to wrap the cable, it is better for the tape itself to be highly flexible and elastic. need to be used. used. As the chlorinated rubbery polymer, rubbery polymers with sufficient flexibility such as chloroprene, chlorsulfonated polyethylene, epichlorohydrin rubber, and crystalline chlorinated polyethylene are preferred, especially when chlorinated polyethylene is used. This is more desirable because the self-fusion property is further improved. The purpose of the blend of ethylene vinyl acetate copolymer is to maintain self-fusing properties even when the chlorine-based rubbery polymer is vulcanized. If a chlorine-based rubber-like polymer is used alone, although it self-fuses when vulcanized, there are problems such as vulcanization progressing during storage and loss of self-fusing properties, and a lack of strength that may cause the tape to deform. There was a problem where the tape broke after being wrapped. Further, polyisobutylene or chroman resin is generally added to impart self-fusion properties, but these are undesirable because they significantly reduce flame retardancy. On the other hand, when an ethylene vinyl acetate copolymer is blended, sufficient self-fusion properties can be obtained without reducing flame retardancy. As the ethylene-vinyl acetate copolymer, one having a vinyl acetate content of 30% to 85% and a melt index of 10 or more is used in order to impart sufficient self-fusing properties. In addition, the mixing ratio of the chlorine-based rubbery polymer and the ethylene-vinyl acetate copolymer is such that when the ratio of the chlorine-based rubbery polymer is in the range of 30% to 70% by weight relative to the sum of both, the present invention can achieve the purpose of i.e. 30
If it is less than 70% by weight, sufficient strength cannot be obtained;
If it exceeds this value, sufficient self-bonding properties cannot be obtained. If necessary, an inorganic filler is blended, and as the inorganic filler, those normally used as fillers for rubber, such as clay, talc, aluminum hydroxide, and calcium carbonate, are used. Further, organic flame retardants, anti-aging agents, etc., which are generally widely used, can be used as needed. It is preferable that these compounding agents give the tape flame retardancy of 30 or more, preferably 35 or more in terms of oxygen index. Vulcanizing agents include zinc oxide, magnesium oxide, metal oxides such as lead oxide, sulfur compounds such as ethylene thiourea, etc.
A vulcanizing agent that is effective for chlorinated rubbery polymers is used. Further, vulcanizing agents such as peroxide which are effective for ethylene-vinyl acetate copolymers are undesirable because they reduce self-fusion properties. In order to examine the effects of the present invention, tapes of various formulations were prepared, wrapped around a 10 mm diameter glass rod, left to stand for 1 hour, then cut open with a knife to determine whether the tape could be peeled off or not to determine self-adhesiveness. 6kv more
-150mm ² CV cable wrapped with 1.0mm thick tape twice in a 1/2 wrap was subjected to a vertical combustion test on an oven tray as specified in IEEE383 to examine its effectiveness in preventing the spread of fire. As a result, as shown in Table 1, it was found that the tape of the present invention had excellent self-bonding properties and had a good fire spread prevention effect.

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Claims (1)

[Scope of Claims] 1. A chlorine-based rubbery polymer and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 30 to 85% and a melt index of 10 or more in a proportion of the chlorine-based rubbery polymer. 30 to 70% by weight, and the chlorine-based rubbery polymer is vulcanized and the ethylene-vinyl acetate copolymer is not vulcanized. Self-fusing tape. 2. The self-fusing tape for preventing the spread of fire in electric wires and cables according to claim 1, wherein the chlorinated rubbery polymer is chlorinated polyethylene.