JPH0576726B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of the Invention] The present invention relates to a flame-retardant tape for protecting cables, and more particularly, to a flame-retardant tape for protecting cables, which has good flame retardancy, does not generate toxic gas in the event of a fire, and does not corrode electric wires. This invention relates to flame retardant tape for protecting cables. [Background of the Invention] Cables such as communication cables buried in underground tunnels, etc., can have a great impact on communication if they burn in the event of a fire accident in the tunnel, so recently it has been Flame retardancy has become an urgent need. It is difficult to make the cable itself flame retardant since the cable sheath is made of polyethylene, and therefore it has been made flame retardant by wrapping the cable with a flame retardant tape. This type of flame retardant tape for protecting cables is
As shown in the figure, the tape has a structure in which a rubber layer 3 is formed on one side of a base fabric 1 with an adhesive layer 2 interposed therebetween, and an adhesive layer 4 is formed on the opposite side of the base fabric 1. are doing. In order to make a tape having such a structure flame retardant, the following methods have been conventionally employed. The rubber layer 3 is an olefin polymer.
A method of blending a halogen-containing polymer or copolymerizing with the halogen-containing polymer to make it flame retardant; adding a halogen-based flame retardant to the rubber layer 3; adding a halogen-based flame retardant to the rubber layer 3; A method of adding inorganic flame retardants, in which a combination of phosphorus, antimony, zircon, etc., and inorganic flame retardants are added. As mentioned above, various methods of making tape flame retardant have been studied, but first, as shown in ~ above, flame retardant adding a halogen-containing flame retardant or using a halogen-containing polymer has flame retardant properties. Although it is good, it has the disadvantage that it generates halogen gas when burned. This halogen-based gas is known to have the drawback of not only being toxic to the human body, but also corroding electric wires, and there is a need for a method of making tape flame-retardant without using halogen-based compounds. As a flame retardant method that does not contain such halogen compounds, there is a method of adding the above-mentioned inorganic flame retardant, such as aluminum hydroxide, to the rubber layer 3. However, if the inorganic flame retardant is added to a high level in order to obtain the desired flame retardancy, the processability and physical properties of the tape will significantly deteriorate, making it impossible to use the tape. The disadvantage was that it could no longer be provided for. Therefore, when adding an inorganic flame retardant, there is no other way than to sacrifice flame retardancy to some extent and lower the filling amount to a processable range. [Summary of the invention] The present invention has been made in view of the above points, and
The object of the present invention is to provide a flame-retardant tape for cable protection that uses an inorganic flame retardant and has good flame retardancy and workability. Therefore, the flame retardant tape for cable protection according to the present invention is a flame retardant tape for cable protection in which a rubber layer is formed on one side of a base fabric, and the rubber layer is made of ethylene propylene diene monomer (hereinafter referred to as EPDM). ) and butyl rubber from 95 to 50:5 to
It is characterized in that 150 parts by weight or less of aluminum hydroxide and 200 to 600 parts by weight of magnesium hydroxide are blended with 100 parts by weight of a rubber base blended at a weight ratio of 50. According to the flame retardant tape for cable protection according to the present invention, a blend of EPDM and butyl rubber is used as the base rubber, and a mixture of aluminum hydroxide and magnesium hydroxide is added as an inorganic flame retardant. Because
Compared to conventional cable protection flame retardant tapes using inorganic flame retardants, this tape has the advantage that it can be made into a tape with good flame retardancy without impairing processability and physical properties. [Specific Description of the Invention] The present invention will be described in more detail. The basic structure of the flame retardant tape for cable protection according to the present invention is the same as that of the conventional tape shown in FIG. 1, and therefore will be described below with reference to FIG. The flame retardant tape for cable protection according to the present invention includes:
As is clear from FIG. 1, a rubber layer 3 is laminated on one side of the base fabric 1 via an adhesive layer 2, and an adhesive layer 4 for winding and pasting the cable on the other side. is formed. The base fabric 1 is not limited in the present invention, and may be a base fabric conventionally used in this type of flame retardant tape, such as glass cloth. A rubber layer 3 is formed on one side of the base fabric 1, and the glue layer 2 for bonding the rubber layer 3 and the base fabric 1 is capable of bonding the base fabric 1 and the rubber layer 3 together. It can be anything. Usually, the same rubber as the material of the rubber layer 3 or a similar rubber is used. In the present invention, the base material of the rubber layer 3 is a mixture of EPDM and butyl rubber, which is different from the conventional method. EPDM is a rubber with good weather resistance and has been conventionally used in this type of tape, but it has the disadvantage that processability and physical properties are significantly reduced when it is highly loaded with inorganic flame retardants. Therefore, in the present invention, EPDM: butyl rubber = 95~
They are blended at a weight ratio of 50:5 to 50 to ensure that processability and physical properties do not deteriorate even when the inorganic flame retardant is highly charged. If the amount of butyl rubber mentioned above is less than 5, the effect of adding butyl rubber will not appear in terms of processability, and on the other hand, if it exceeds 50,
There is a risk that the weather resistance, which is a characteristic of EPDM, may be impaired. Aluminum hydroxide and magnesium hydroxide are used as flame retardants to be mixed into such a rubber base material. This aluminum hydroxide is a rubber base material.
150 parts by weight or less is added per 100 parts, while magnesium hydroxide is added in an amount of 200 to 600 parts by weight. This is because if the amount of aluminum hydroxide added as a flame retardant exceeds 150 parts by weight, workability (roll workability) may be reduced. Compared to aluminum hydroxide, magnesium hydroxide does not significantly reduce workability even when it is highly filled. Therefore
Although it is highly loaded at 200 to 600 parts by weight, if the amount of magnesium hydroxide added is less than 200 parts by weight, there is a risk that the flame retardant improvement effect will be small, whereas if it exceeds 600 parts by weight, There is a risk that the rubber layer may burst in the event of a fire. It is of course possible to optionally add conventional additives such as a vulcanizing agent, a heating accelerator, and a processing aid to such a rubber layer 3. FIG. 2 is a sectional view of a second configuration example of the flame retardant tape for cable protection of the present invention. A metal foil layer 6 is provided on the adhesive layer 5. This metal foil layer 6 is provided to prevent the burning material from falling when the tape is burned and to improve the flame retardancy of the tape. Since the tape is wound around cables, etc., such metal foil is required to have malleability and plasticity, but as long as it satisfies these conditions, it is basically It can be anything. For example, aluminum foil can be used. Next, examples of the present invention will be described. Example 1 A flame-retardant tape for cable protection having a rubber layer having the composition shown in Table 1 below and having the structure shown in FIG. 1 was manufactured, and its oxygen index was measured according to JISK7201.
Tapes with an oxygen index of 40 or higher can be put to practical use.

[Table] FIG. 3 shows the changes in the oxygen index of Examples 1 to 3 described above. In the figure, ○ indicates a graph of changes in oxygen index when varying amounts of the aluminum hydroxide/magnesium hydroxide mixed inorganic flame retardant according to the present invention are added, and A, B, and C are examples, respectively. Values corresponding to 1, 2, and 3 are shown. For comparison, the change in oxygen index when varying the amount of aluminum hydroxide added to 100 parts by weight of EPDM is also shown in the same figure. In the figure, ● indicates the change in the oxygen index of the conventional flame-retardant tape. As is clear from FIG. 3, the flame retardant tape according to the present invention can be filled with a higher flame retardant than the conventional tape, and while the oxygen index of the conventional tape is 57.5 as the upper limit, the flame retardant tape according to the present invention In the tape by
Can exceed 80. In addition, in order to compare the physical properties of the tape, the tensile strength and adhesive strength were measured using JIS Z 1524 and JIS
The tapes described in Example 3 and Comparative Example 3 were each measured using C-2107. The results are shown in Table 2.

〔Effect of the invention〕

As explained above, the flame retardant tape for cable protection according to the present invention has the advantage that it can be highly filled with a flame retardant, so that flame retardance can be improved without impairing the tape physical properties and processability. There is. Furthermore, the flame retardants to be filled are aluminum hydroxide and magnesium hydroxide, and since they do not contain halogen, they do not generate toxic gases when burned, and since the aluminum hydroxide and magnesium hydroxide water are hydrated compounds, It also has the advantage of significantly suppressing smoke generation.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a flame-retardant tape for cable protection, FIG. 2 is a cross-sectional view of a specific example of the flame-retardant tape for cable protection according to the present invention, and FIG. 3 is a cross-sectional view showing the structure of a flame-retardant tape for cable protection according to the present invention. FIG. 2 is a diagram showing the relationship between Examples 1, 2, and 3 of flame retardants for flame retardant tapes and oxygen index. 1...Base fabric, 3...Rubber layer, 5...Metal foil.

Claims (1)

[Claims] 1. In a flame retardant tape for cable protection in which a rubber layer is formed on one side of a base fabric, the rubber layer is
Contains 150 parts by weight or less of aluminum hydroxide and 200 to 600 parts by weight of magnesium hydroxide to 100 parts by weight of a rubber base material blended with ethylene propylene diene monomer and butyl rubber at a weight ratio of 95 to 50:5 to 50. A flame-retardant tape for protecting cables.