JP3201085B2 - Injection type fireproof cable connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable connection, and more particularly, to a cable connection having an injection-type refractory layer.

[0002]

2. Description of the Related Art An example in which fire-resistant cables specified in the Fire Service Agency Notification No. 7 are connected in a straight line will be described with reference to cross-sectional views of FIGS. In the cross-sectional views of FIGS. 3 and 4 showing the configuration of the straight connection portion of the fireproof cable,
The ends of the refractory cables 1a and 1b are stripped to expose the respective cable conductors 11a and 11b,
These are butted in the straight connection conductor tube 2 and are compressed and connected. Next, a fire-resistant tape is wrapped around the straight connection conductor tube 2 and the cable conductors 11a and 11b connected in this manner, over the fire-resistant layer 3 of the same material as the cable fire-resistant layers 12a and 12b, between the cable fire-resistant layers 12a and 12b. To form. Further, as shown in FIG. 4, a polyethylene tape is provided thereon with a cable cross-linked polyethylene insulator 13a, 1.
3b to form an insulating layer, which is then cross-linked to cover the insulating layer 4 such as cross-linked polyethylene;
On this, the connection part protection layer 5 is provided with the cable sheaths 14a,
The straight connection portion is formed over the area b. As the above-mentioned fire-resistant tape, a tape obtained by attaching laminated mica to a glass cloth is generally used.

[0003]

As described above, the fire-resistant tape is wound around the cable conductors 11a and 11b and the straight connection conductor tube 2 to form the fire-resistant layer 3. The fire-resistant tape is made of mica and glass cloth. It is difficult to wind the tape when it is wound around a place where the tape itself does not stretch and has many irregularities, and if it is applied to a T-shaped branch connection as shown in FIG. 1, it becomes impossible to wind the tape. That is, the branch connection pipe 6 constituting the T-shaped branch connection portion
Consists of three sides of branch conductor connection pipes 6a, 6b, 6c,
The refractory tape cannot be wound around the branch point 61 which is the center of the conductor.

[0004] The present invention has been made in view of such a point, and a novel injection type fire-resistant cable connection body which can easily form a fire-resistant layer provided on a conductor of a cable connection portion or a conductor connection pipe. The purpose is to provide.

[0005]

According to the present invention, an injection type refractory layer comprises a copolymer of ethylene and a carboxyl group-containing monomer or a derivative thereof alone, an ethylene-alkyl acrylate copolymer alone, or a blend of these with a polyolefin. 100 parts by weight, metal hydroxide 150
An injectable refractory layer having an oxygen index of 40 or more on a conductor at a cable connection portion or on a sleeve at a cable connection portion. It is an injection type fireproof cable connection body characterized by having provided. The carboxyl group content or the acrylic acid content in the polymer alone or in the blended polymer is 40% by weight or more.

[0006]

[Function] Ethylene and carboxyl group-containing monomer
Is a copolymer with its derivative and ethylene-acrylic acid
Alkyl copolymers are polymers that themselves have flame retardancy
However, when used in combination with metal hydroxide, flame retardancy is further improved.
And melts when exposed to high temperatures during a fire
The carbonized layer is less likely to drip due to
It is easy to form and excellent fire resistance is exhibited .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The injection type refractory layer of the present invention must have an oxygen index of 40 or more. This is because if it is less than this value, it is not possible to provide the fire resistance performance aimed at by the present invention.

The polymer applicable to the present invention is preferably a copolymer of ethylene and a carboxyl group-containing monomer or a derivative thereof, or an ethylene-alkyl acrylate copolymer, and specifically, an ethylene-vinyl acetate copolymer. And ethylene-methyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene-acrylate copolymer and the like. These may be used alone or in combination
Good. These polymers were exposed to high temperatures during a fire
Even in the case, dripping by melting is unlikely to occur.
Excellent flame retardancy when used in combination with metal hydroxides described below
And has a carbonized layer forming property. These polymers and other
Polyolefins such as polyethylene, ethylene butene
Copolymer and ethylene propylene copolymer.
Can also be.

In the present invention, 150 to 300 parts by weight of a metal hydroxide such as aluminum hydroxide, magnesium hydroxide, hydrotalcite, basic magnesium carbonate and calcium aluminate is mixed with 100 parts by weight of the polymer. If the mixing amount of the metal hydroxide is less than the above specified value, the fire resistance performance aimed at by the present invention is not obtained, and if it exceeds the above specified value, the workability of injection molding is significantly reduced. . Since these metal hydroxides are decomposed while releasing water of crystallization at the temperature at the time of fire, the formation of a carbonized layer by the decomposition of the polymer component is effectively performed.

According to the present invention, the refractory layer formed during combustion is strengthened by using at least one of calcium carbonate, talc, clay and calcium silicate in combination with the metal hydroxide, and the refractory performance is greatly improved. It was found that it could be improved. This is considered to have a carbonization promoting effect upon decomposition of the polymer. Such carbonization promoting action
Is recognized, based on 100 parts by weight of the polymer,
It is necessary to mix at least 10 parts by weight. Hereinafter, specific examples of the mixing ratio of the material forming the refractory layer will be described. (The amount is in parts by weight.)

Example 1 Ethylene vinyl acetate copolymer 100 [Melt index (190 ° C.) = 10, vinyl acetate content 60% by weight] Magnesium hydroxide (average particle size 0.8 μm, oleic acid treatment) 250 Talc 30 Stearin Acid 3 FEF carbon 5

Example 2 Ethylene-acrylate copolymer 100 (Mouni viscosity ML1 + 4 100 ° C. = 1.6, acrylate content 59% by weight) Aluminum hydroxide (average particle size 2 μm, stearic acid treatment) 230 silica Calcium acid salt 40 stearic acid 3 FEF carbon 5

Comparative Example 1 Ethylene propylene rubber 100 (Mouni viscosity ML1 + 4 100 ° C. = 10) Aluminum hydroxide (average particle size 2 μm, stearic acid treatment) 200 Talc 40 Stearic acid 3 FEF carbon 5

Comparative Example 2 Ethylene vinyl acetate copolymer 100 [Melt index (190 ° C.) = 10, vinyl acetate content 10% by weight] Magnesium hydroxide (average particle size 0.8 μm, oleic acid treatment) 120 Talc 30 Stearin Acid 3 FEF carbon 5

Comparative Example 3 Ethylene vinyl acetate copolymer 100 [Melt index (190 ° C.) = 10, vinyl acetate content 60% by weight] Magnesium hydroxide (average particle size 0.8 μm, oleic acid treatment) 250 Talc 5 Stearin Acid 3 FEF carbon 5

A refractory layer was formed based on the compounding ratios shown in Examples 1 and 2 and Comparative Examples 1 to 3. That is, a sample was formed on the refractory layer of the branch connection unit shown in FIG. That is, the branch connection pipe 6 for branch connection of the cable is
The T-shaped branch conductor connection pipes 6a, 6b, and 6c are used. A so-called injection mold connection method is used on the outer periphery of the connection pipe, and the mixture is injected into a mold using an injection molding machine or a compression injection machine. After the mixture hardens, the mold is removed to form the refractory layer 7. Further, an insulating layer 8 made of polyethylene or the like is formed on this in advance at a factory. And
The branch connection of the fireproof cable is performed on site using this branch connection unit.

Conductor size 200 mm ² , 6.6 kV crosslinked polyethylene insulated trunk cable and conductor size 60 mm
^In a 2,6.6 kV cross-linked polyethylene insulated T-type branch connection unit, an injection type refractory layer 7 was coated on a conductor to a thickness of 3 mm, and a branch unit insulator 8 was provided thereon. Table 1 shows the oxygen index and fire resistance test results of each example.

[0018]

[Table 1]

Using the branch connection unit formed with the injection type refractory layer of Examples 1 and 2 and connecting portion protection layer 5 provided thereon as shown in FIG.
Test of fire temperature curve (exposure test, 4.4kV3
At 0 minutes, with a maximum temperature of 840 ° C), the fire resistance specified in the Fire and Disaster Management Agency Notification No. 7 No. 3 (immediately after reaching 840 ° C)
MΩ · km or more).

On the other hand, Comparative Example 1 using an unspecified polymer and Comparative Example 2 in which the amount of metal hydroxide mixed was less than the limit value
In the case of Comparative Example 3 in which the amount of talc and the amount of talc were less than the limit value, all were short-circuited during the fire resistance test for 30 minutes, and were rejected.

[0021]

As described above, the injection-type fire-resistant cable connecting body of the present invention can be molded integrally and integrally on a conductor having irregularities or a branch connection conductor. It will be improved. In addition, especially in the case of a branch connection portion or the like, a fire-resistant tape could not be conventionally wound around a branch point of a branch conductor, and a complete fire-resistant layer could not be formed. The fireproof layer of the branch connection can be easily formed,
The effect of reducing the on-site work and obtaining a cable connector having a reliable fireproof layer is extremely large.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an injection type fire-resistant cable branch connection unit according to one embodiment of the present invention;

FIG. 2 is a sectional view when a branch connection unit is formed using the branch connection unit of FIG. 1;

FIG. 3 is a cross-sectional view showing a configuration of a conventional fire-resistant cable straight-line connection unit.

FIG. 4 is a cross-sectional view when a straight connection portion is formed using the straight connection unit of FIG. 3;

[Explanation of symbols]

 1a, 1b Fireproof cable 3 Fireproof layer 4 Insulation layer 5 Connection protection layer 6 Branch connection pipe 11a, 11b Cable conductor 12a, 12b Cable fireproof layer 13a, 13b Cable cross-linked polyethylene insulator 14a, 14b Cable sheath

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08L 23/00 C08L 23/00 23/08 23/08 (72) Inventor Katsuo Moriya 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture (72) Inventor Yasuyuki Sasaki 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture "Inside the Hidaka Factory, Hitachi, Ltd." (58) Investigator (Int .Cl. ⁷ , DB name) H02G 15/08 C08K 3/22 C08K 3/26 C08K 3/34 C08K 23/00 C08K 23/08

Claims (1)

(57) [Claims] An injection-type refractory layer is composed of a copolymer of ethylene and a carboxyl group-containing monomer or a derivative thereof alone, an ethylene-alkyl acrylate copolymer alone, or a blend of these and a polyolefin in 100 parts by weight of metal water. Oxygen index of 150 to 300 parts by weight, further mixed with calcium carbonate, talc, clay, 10% by weight or more of calcium silicate, on the conductor of the cable connection portion or on the sleeve of the cable connection portion.
An injectable refractory cable connection, comprising zero or more injectable refractory layers.