JPH0127398Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a heat-shrinkable tube, and in particular,
For example, the present invention relates to a heat-shrinkable tube for insulation shielding used as an insulated connection part of a rubber/plastic insulated power cable.

Conventionally, an example of the insulated connection part of a rubber/plastic insulated power cable is shown in Figure 1.
The insulating shielding layer 5 was formed by cutting edges with slits 6. That is, the connecting portions of both conductors 1 and 1' to be connected are covered and connected with the internal semiconducting layer 2,
Both cable insulators 3 shaped like sharpened pencils
The concave portion between them is filled with a connecting portion reinforcing insulating layer 4, and the insulating shielding layer 5 is further formed with slits 6 on the outer periphery.
The edges were cut and covered. However,
The method for forming it was to wind a semi-dynamic tape and an insulating tape for a reinforcing insulating layer, heat and press them, and fuse them together.

However, conventional connections made by this method have the following problems. That is, (a) When each tape is wound, heated and pressurized as described above, and fused and integrated, the tip of the insulating shielding layer 5 forming the slit 6 is deformed, and the tip of the insulating shield layer 5 is deformed. Since the electric field becomes larger, the formed connection becomes more likely to break from its tip.

(b) When manufacturing the slits 6 in the insulating shielding layer 5, it is difficult to make them coaxially concentric. Therefore, disturbances in the electric field are likely to occur.

The purpose of the present invention is to solve the above-mentioned problems and provide a heat-shrinkable tube for an insulating connection part that can form an electrically stable insulating shielding layer.

As an embodiment of the heat-shrinkable tube of the present invention is shown in FIG. 2, one region 8 in the longitudinal direction has a volume resistivity of 10 ⁷ to 10 ¹² Ω-cm over the entire circumference;
It is characterized in that it is made of a material with a dielectric constant of 10 or more, and that both other regions 7 adjacent to the region 8 are made of a material with a volume resistivity of 10 ⁵ Ω-cm or less over the entire circumference. shall be.

That is, both of the other regions 7 are made of a semiconductive material with a volume resistivity of 10 ⁵ Ω-cm or less, such as a conventionally obtained ethylene copolymer and conductive carbon. A conductive material such as a composition to which black is added to impart semiconductivity can be used.

Moreover, the volume resistivity of the area 8 is 10 ⁷ ~
It is made of a material with a high resistance of 10 ¹² Ω-cm and a high dielectric constant of 10 or more, and is obtained by blending one or more of the following fillers with a rubber or plastic base. It will be done. That is, fillers include titanium compounds such as titanium dioxide and barium titanate, silicon carbide, zinc oxide, tin oxide, iron, copper,
Metal powder such as aluminum or nickel, carbon black, etc. are used.

Examples of the base rubber/plastic include ethylene-propylene rubber, ethylene-propylene-diene copolymer, butadiene rubber, acrylonitrile rubber, fluorocarbon rubber, urethane rubber, styrene-butadiene rubber, silicone rubber, chlorosulfonated polyethylene, Butyl rubber, chloroprene rubber, nitrile rubber, chlorinated polyethylene, polyvinyl chloride, ethylene-α-olefin-diene terpolymer, low-density polyethylene, high-density polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate copolymer, etc. One type or a blend of two or more types can be used.

Further, a vulcanizing agent, a vulcanization accelerator, an antioxidant, and a processing aid may be used as necessary.

Next, when an insulating connection portion is formed using the product according to the embodiment of the present invention as shown in FIG. 3, the following effects can be obtained.

(a) The breakdown value does not decrease due to deformation of the semiconducting layer 5 (see FIG. 1) forming the slit 6 as in the conventional case, and the characteristics of the insulating connection portion are improved.

(ro) The shape is no different from the normal straight connection part (3rd
(see figure), making it very easy to manufacture.

(a) Compared to conventional insulated connections, it has the advantage of being able to be constructed in a shorter time.

Next, an example of the method for manufacturing the heat-shrinkable tube of the present invention will be described. A semiconductive material and a high-resistance, high-permittivity material having the above-mentioned characteristics are each formed into a 0.3 mm thick film using an inflation film forming machine. These films were crosslinked by irradiating them with a 10 Mrad electron beam, and then stretched. Using both films after stretching, arrange each film so that it has the desired shape and inner diameter of the high-resistance and high-permittivity layer, wrap it overlappingly, and then heat and integrate it into one heat-shrinkable tube. was manufactured.

The reasons why the above-mentioned conventional problems can be solved by using the heat-shrinkable tube of the present invention are as follows: (1) Since the shape is made in advance, the desired shape can be obtained more easily than by wrapping tape around the mold. .

(2) Crosslinking treatment is performed to create a heat-shrinkable tube, resulting in a semi-crosslinked state, which makes it difficult for the material to flow when heated and pressurized. etc.

The present invention will be further described below with reference to embodiments.

Example 1 Ethylene-ethyl acrylate (product name: DPDJ- manufactured by Nippon Unicar Co., Ltd.
6169) 100 parts by weight, 50 parts by weight of conductive carbon black (acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.), 0.2 parts by weight of antioxidant (trade name Nokrac 300 manufactured by Ouchi Shinko Kagaku Co., Ltd.), and crosslinking agent. A composition containing 1.0 part by weight of dicumyl peroxide was used.

On the other hand, as a material for forming a high-resistance, high-permittivity layer material, i.e., a region 8 in the center shown in Figure 2, ethylene-ethyl acrylate (product name: DPDJ-6169, manufactured by Nippon Unica Co., Ltd.) is used in an amount of 100 parts by weight. ,
A composition was used in which 150 parts by weight of silicon carbide, 0.2 parts by weight of an antioxidant (trade name Nokrac 300, manufactured by Ouchi Shinko Kagaku Co., Ltd.), and 1.0 parts by weight of dicumyl peroxide, a crosslinking agent, were added.

Heat-shrinkable tubes having the following dimensions were manufactured using cross-linked stretched films made of both of these compositions in each region 7 and 8, respectively.

Tube inner diameter: 105 mmφ Thickness of tube side wall: 2 mm Width of the high-resistance, high-permittivity layer, that is, the area 8 at the center: 140 mm The characteristics of this heat-shrinkable tube were as follows.

(1) Shrinkage rate...40% (2) Volume resistivity of semiconducting layer 7...2 x 10 ² Ω-cm (3) Volume resistivity of high resistance high dielectric constant layer 8... 7 x 10 ⁸ Ω -cm (4) Similarly, the dielectric constant of layer 8... 30 heat-shrinkable tubes are 154KVCV cable 600
It was used as an insulating shielding layer (corresponding to reference numeral 5 in FIG. 1) of an insulated connection of mm ² (see FIG. 3) to form a connection. The molding method is as follows.

After connecting the conductors 1 and 1' with a compression sleeve (not shown), a semiconductive tape was wound around the conductor connection to form an internal semiconductive layer 2, which was then heated and formed. Next, a connection reinforcing insulator layer 5 is formed by extrusion,
The high-resistance, high-dielectric-constant layer 8, that is, the high-resistance high-dielectric-constant layer 8, of the heat-shrinkable tube of this embodiment is inserted on its periphery so as to be located exactly on the connection portion of the conductors 1, 1'.
Finally, this was heat-shrinked and fused and integrated onto the insulating layer.

When the formed insulated connection part was subjected to a breakdown test, the breakdown value was 720 KV, which was good, and the workability was also good.

Example 2 Ethylene-propylene rubber (product name: EP-21, manufactured by Japan Synthetic Rubber Co., Ltd.) 100% was used as the semiconductive layer material, that is, the molding material for both areas 7 shown in FIG.
A composition was used in which 60 parts by weight of conductive carbon black (Acetylene Black manufactured by Denki Kagaku Kogyo Co., Ltd.) and 0.25 parts by weight of an antioxidant (trade name Nokrac 300 manufactured by Ouchi Shinko Kagaku Co., Ltd.) were added to the parts by weight. there was.

On the other hand, as a material for forming the high-resistance and high-permittivity layer material, i.e., the central area 8 shown in Figure 2, 100 parts by weight of ethylene-propylene rubber (product name EP-21 manufactured by Japan Synthetic Rubber Co., Ltd.) was used. , silicon carbide
200 parts by weight, 5 parts by weight of conductive carbon black (product name: KETSUCHING BRATSU EC, manufactured by Lion Akzo Co., Ltd.), and 0.25 parts by weight of an antioxidant (product name: NOCRATSUKU 300, manufactured by Ouchi Shinko Kagaku Co., Ltd.) was used. .

A heat-shrinkable tube having the same shape as in Example 1 was manufactured by using cross-linked stretched films made of both of these compositions in each region 7 and 8, respectively.

The characteristics of this heat-shrinkable tube were as follows.

(1) Shrinkage rate...40% (2) Volume resistivity of semiconducting layer 7...3 x 10 ³ Ω-cm (3) Volume resistivity of high resistance high dielectric constant layer 8... 5 x 10 ⁸ Ω -cm (4) Similarly, the dielectric constant of layer 8... 40 heat-shrinkable tubes and 154KVCV cables 600
The connection was formed in the same manner as in Example 1, using it as an insulating shielding layer (corresponding to reference numeral 5 in FIG. 1) for an insulated connection of mm ² (see FIG. 3).

When the obtained insulated connection part was subjected to an electrical test in the same manner as in Example 1, it was found that the breakdown was 750 KV, which was good, and the workability was also good.

Comparative Example Based on the conventional method, as shown in FIG.
Edge cutting parts were provided at intervals of 2 mm between 6 slits. The electrical test result of the connection part of 154CV cable ^600mm2 was destructive at 440KV.

As described above, as an effect of the present invention, by using the heat-shrinkable tube of the present invention, a cable connection part with excellent electrical properties and good workability can be obtained, and the present invention is industrially useful. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a conventional insulated connection part in a rubber-plastic insulated power cable, FIG. 2 is a perspective view of an example of the present invention, and FIG. FIG. 3 is a longitudinal cross-sectional view showing an insulated connection part constructed using an example product. 1, 1'...Conductor, 2...Inner semiconducting layer, 3...
...Cable insulator, 4... Connection reinforcing insulator layer,
5... Connecting portion external semiconducting layer, 6... Slit portion,
7...Semiconducting layer, 8...High resistance and high dielectric constant layer.

Claims (1)

[Scope of utility model registration request] In a heat-shrinkable tube, one area in the longitudinal direction has a volume resistivity of 10 ⁷ to 10 ¹² Ω over the entire circumference.
-cm, is made of a material with a dielectric constant of 10 or more, and both other areas adjacent to this area are made of a material with a volume resistivity of 10 ⁵ Ω-cm or less over the entire circumference. Features a heat-shrinkable tube.