JP5491838B2 - Power cable - Google Patents

Description

  The present invention relates to a power cable.

  A high voltage power cable of 3.3 kV or higher generally has a cross-linked polyethylene insulator layer and an external semiconductive layer on the outside of the conductor. Among the external semiconductive layers of the above power cable, those that can be peeled off from the insulator layer for facilitating the end treatment are called free stripping type semiconductive layers and are usually 3.3 to 33 kV power cables. Has been applied. The external semiconductive layer is required to have peelability as well as appropriate adhesion to the insulator layer.

  As such a free stripping type external semiconductive layer, for example, a composition obtained by extruding a composition in which conductive carbon black and an antioxidant are added to a specific resin material including an ethylene vinyl acetate copolymer or the like. Is known (Patent Document 1 below).

Japanese Patent Publication No. 63-32204

  However, even when the external semiconductive layer is formed using the composition described in Patent Document 1, the external semiconductive layer may not be easily peeled from the insulator layer. For this reason, the room for improvement was still left about the composition for external semiconductive layers from a viewpoint of performing the terminal process of an electric power cable efficiently.

  This invention is made | formed in view of the said situation, and it aims at providing the electric power cable which can perform a terminal process efficiently.

  In order to solve the above-mentioned problems, the present inventor has intensively studied focusing on an antioxidant, particularly an imidazole compound, added to the composition for forming an external semiconductive layer. As a result, the present inventors insulated the imidazole compound, although the external semiconducting layer cannot be easily peeled off from the insulating layer only by using the imidazole compound as an antioxidant added to the composition for forming the outer semiconducting layer. Surprisingly, it was found that the external semiconductive layer can be easily peeled off from the insulator layer by adding it to the composition for forming the body layer, and the present invention has been completed.

That is, the present invention relates to an insulator layer comprising a conductor and a resin composition for an insulator layer containing polyethylene, and then cross-linked. The insulator layer surrounds the conductor, and an outer semiconductive layer containing a polymer and a conductive material. An external semiconductive layer formed by extruding the resin composition so as to cover the insulator layer and then crosslinking, and both the resin composition for the insulator layer and the resin composition for the external semiconductive layer. An imidazole compound is included , and the resin composition for an insulator layer is blended in a proportion of 0.02 to 0.3 parts by mass with respect to 100 parts by mass of the polyethylene, In the resin composition for a semiconductive layer, the imidazole compound is blended at a ratio of 0.02 to 0.3 parts by mass with respect to 100 parts by mass of the polymer .

According to this power cable, since both the resin composition for an insulator layer and the resin composition for an external semiconductive layer contain an imidazole compound, the external semiconductive layer can be easily separated from the insulator layer. Terminal processing can be performed efficiently. In this case, as compared with the case where the imidazole compound is contained within the above range, moderate adhesion to the insulator layer tends to be imparted. Furthermore, in this case, there is a tendency that moderate adhesion is imparted to the insulator layer as compared with the case where the imidazole compound is contained within the above range.

  The power cable may further include an internal semiconductive layer provided between the conductor and the insulator. This power cable is particularly useful, for example, for high voltages of 3-6 kV. That is, even if this power cable is used for such a high voltage application, it is possible to suppress dielectric breakdown of the insulator layer.

  ADVANTAGE OF THE INVENTION According to this invention, the power cable which can perform a terminal process efficiently is provided.

It is a partial side view which shows one Embodiment of the power cable of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

  FIG. 1 is a cross-sectional view showing an embodiment of a power cable according to the present invention. As shown in FIG. 1, the power cable 10 includes a conductor 1, an internal semiconductive layer 2 covering the conductor 1, an insulator layer 3 covering the internal semiconductive layer 2, and an external covering the insulator layer 3. A semiconductive layer 4. Here, the insulator layer 3 surrounds the conductor 1, is formed by extrusion molding of a resin composition for insulator layer containing polyethylene, and is cross-linked. The outer semiconductive layer 4 is a so-called free stripping type. It is a semiconductive layer, and is formed by extruding a resin composition for an external semiconductive layer containing a polymer and a conductive substance so as to cover the insulator layer 3 and then crosslinking. Both the resin composition for an insulator layer and the resin composition for an external semiconductive layer contain an imidazole compound. The power cable 10 may further include a shielding layer, a pressing tape layer, and a sheath (not shown) outside the external semiconductive layer 4. The thickness of the insulating layer 3 is, for example, 3 to 10 mm, and the thickness of the external semiconductive layer 4 is, for example, 0.2 to 2 mm. The power cable 10 is particularly useful for high voltage applications where the operating voltage is 3.3 to 33 kV.

According to this power cable 10, since the imidazole compound is contained in both the resin composition for the insulator layer and the resin composition for the external semiconductive layer, the external semiconductive layer 4 is peeled from the insulator layer 3. Can be easily performed, and terminal processing can be performed efficiently.
Moreover, since the power cable 10 includes the internal semiconductive layer 2, even if it is used for a high voltage of 3 to 6 kV, for example, the dielectric breakdown of the insulator layer 3 can be suppressed.

  Next, a method for manufacturing the power cable 10 will be described.

  That is, first, a conductor 1, a resin composition for an outer semiconductive layer containing a polymer, a conductive material, and an imidazole compound, a resin composition for an insulator layer containing polyethylene and an imidazole compound, and an inner semiconductive layer A resin composition is prepared.

(conductor)
As the conductor 1, a metal wire such as a copper wire, a copper alloy wire, or an aluminum wire can be used. Also, the conductor 1 can be made by plating the surface of the metal wire with tin, silver or the like. The conductor 1 can be a single wire or a stranded wire.

(Resin composition for external semiconductive layer)
As described above, the resin composition for the external semiconductive layer includes a polymer, a conductive material, and an imidazole compound.

  As the polymer, an ethylene polymer is usually used. An ethylene polymer means a polymer containing ethylene as a repeating unit. Examples of such ethylene polymers include polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer, and ethylene-ethyl methacrylate copolymer. , Ethylene-1-butene copolymer, ethylene-α olefin copolymer, and ethylene-propylene diene rubber (EPDM). These can be used alone or in combination of two or more.

  Among these, EVA is preferable from the viewpoint of improving the extrusion processability. Here, the EVA content in the polymer is preferably 81% by mass to 100% by mass in order to increase the adhesion to the insulator layer 4 or increase the carbon content.

  As the conductive material, carbon black is usually used. Examples of the carbon black include acetylene black, furnace black, ketjen black, and thermal black. Above all, carbon black is acetylene black, there are few impurities, it does not deteriorate the electrical properties of the polymer, and it does not form large aggregates, and it is an electrical defect at the interface between the polymer and the conductive material. This is preferable because no protrusion is generated.

  The conductive material is more preferably blended at a ratio of 60 to 80 parts by mass with respect to 100 parts by mass of the polymer. In this case, stable electrical resistance (conductivity) can be maintained even when the temperature of the power cable 10 rises.

  Examples of the imidazole compound include 2-mercaptobenzimidazole and 2-methylmercaptobenzimidazole.

  The imidazole compound is preferably blended at a ratio of 0.02 to 0.30 parts by mass with respect to 100 parts by mass of the polymer, and more preferably at a ratio of 0.05 to 0.20 parts by mass. preferable. In this case, compared with the case where the imidazole compound is contained within the above range, moderate adhesion to the insulator layer 3 tends to be imparted.

  In addition, when bridge | crosslinking of the resin composition for external semiconductive layers is performed with a heat | fever, the resin composition for external semiconductive layers may further contain a crosslinking agent. Examples of such a crosslinking agent include dicumyl peroxide.

(Resin composition for insulator layer)
As described above, the resin composition for the insulator layer contains polyethylene and an imidazole compound.

  As the polyethylene, low density polyethylene is usually used, but high density polyethylene or the like may be used.

  As the imidazole compound, the same compounds as described above can be used.

  The imidazole compound is preferably blended at a ratio of 0.02 to 0.30 parts by mass with respect to 100 parts by mass of polyethylene, more preferably at a ratio of 0.05 to 0.2 parts by mass. preferable. In this case, compared with the case where the imidazole compound is contained within the above range, moderate adhesion to the external semiconductive layer 4 and the insulator layer 3 containing the imidazole compound tends to be imparted. .

  Further, from the viewpoint of improving the adhesion between the external semiconductive layer 4 and the insulator layer 3, the blending ratio of the imidazole compound in the resin composition for the insulator layer is the same as that in the resin composition for the external semiconductive layer. It is preferable to do as follows according to the blending ratio of the imidazole compound.

  That is, when the blending ratio of the imidazole compound in the resin composition for the external semiconductive layer is 0.02 to 0.05 parts by mass with respect to 100 parts by mass of the polymer, The mixing ratio of the imidazole compound is preferably 0.02 to 0.30 parts by mass with respect to 100 parts by mass of polyethylene.

  In addition, when the blending ratio of the imidazole compound in the resin composition for the external semiconductive layer is larger than 0.05 parts by mass and 0.15 parts by mass or less with respect to 100 parts by mass of the polymer, the resin for the insulator layer The blending ratio of the imidazole compound in the composition is preferably 0.02 to 0.20 parts by mass with respect to 100 parts by mass of polyethylene.

  Furthermore, when the blending ratio of the imidazole compound in the resin composition for the external semiconductive layer is greater than 0.15 parts by mass and less than 0.25 parts by mass with respect to 100 parts by mass of the polymer, the resin for the insulator layer The blending ratio of the imidazole compound in the composition is preferably 0.02 to 0.20 parts by mass with respect to 100 parts by mass of polyethylene.

  Furthermore, when the blending ratio of the imidazole compound in the resin composition for the external semiconductive layer is greater than 0.25 parts by mass and equal to or less than 0.30 parts by mass with respect to 100 parts by mass of the polymer, The blending ratio of the imidazole compound in the resin composition is preferably 0.02 to 0.05 parts by mass with respect to 100 parts by mass of polyethylene.

  In addition, when bridge | crosslinking of the resin composition for insulator layers is performed with a heat | fever, the resin composition for insulator layers may further contain a crosslinking agent. Examples of such a crosslinking agent include dicumyl peroxide.

(Resin composition for internal semiconductive layer)
The resin composition for the inner semiconductive layer includes a polymer, a conductive material, and an antiaging agent. As a polymer and an electroconductive substance, the thing similar to the polymer and electroconductive substance of the resin composition for external semiconductive layers can be used.

  As an anti-aging agent, an anti-aging agent different from an imidazole compound, for example, a hindered phenol type such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 4 Thiobisphenols such as 4,4'-thiobis- (6-tert-butyl-3-methylphenol), phosphites, phosphorous tris (nonylphenyl) such as tris (mixture- and-nonyl-phenyl) phosphite, Dilauryl thiodipropionate, distearyl thiodipropionate, distearyl-β, β-thiodibutyrate, lauryl stearyl thiodipropionate, sulfur-containing ester compounds, amyl-thioglycolate, 1,1 '-Thiobis- (2-naphthol), hydrazine derivatives and the like can be used. By using such an anti-aging agent, the adhesion between the internal semiconductive layer 2 and the insulator layer 3 can be improved.

  Next, the above three kinds of compositions are extruded on the conductor 1 at a temperature that does not crosslink (for example, about 120 ° C.) by coextrusion molding to form a three-layer laminate, and then introduced into a cross-linked cylinder. Then, pressurization and heating (200 ° C., about 15 atm = about 1.5 MPa) is performed to crosslink the resin composition for the insulator layer and the resin composition for the inner and outer semiconductive layers.

  In this way, the inner semiconductive layer 2, the insulator layer 3, and the outer semiconductive layer 4 are formed on the conductor 1, and the power cable 10 is obtained.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Examples 1 to 16)
First, a resin composition for an external semiconductive layer and a resin composition for an insulator layer were prepared.

The resin composition for an external semiconductive layer was obtained by blending a polymer, a conductive material, a crosslinking agent, and an antiaging agent with the compositions shown in Tables 1 and 2 , and kneading at 120 ° C. The resin composition for forming an insulator layer was obtained by blending a polymer and an antioxidant with the compositions shown in Tables 1-2 and kneading at 120 ° C. In Tables 1 and 2 , the following components were specifically used as the components. Moreover, the unit of the numerical value of Tables 1-2 is a mass part.
(1) Polymer 1
EVA: EV260 (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.)
(2) Conductive substance acetylene black: Denka Black (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.)
(3) Cross-linking agent dicumyl peroxide: Park mill D (manufactured by NOF Corporation)
(4) Anti-aging agent 2-mercaptobenzimidazole: NOCRACK MB (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
(5) Polymer 2
Low density polyethylene (LDPE): UBEC530 (manufactured by Ube Maruzen Polyethylene Co., Ltd.)

  Then, the resin composition for the outer semiconductive layer and the resin composition for the insulator layer are put into a two-layer extruder, and two layers are simultaneously extruded at 120 ° C. to form a two-layer laminate. A conductor (diameter 12 mm) was coated with a laminate of layers. At this time, the resin composition for the external semiconductive layer is extruded so that the thickness after crosslinking is 1 mm, and the resin composition for forming the insulator layer is 3 mm thick. Extruded.

  Next, following the extrusion, the laminate is introduced into a cross-linked cylinder and heated under pressure (200 ° C., about 15 atm = about 1.5 MPa, about 1 to 2 minutes) to form a resin composition for an external semiconductive layer and an insulator. The resin composition for the layer was subjected to crosslinking treatment. Thus, a power cable was obtained.

Then, from the obtained power cable, the external semiconductive layer and the insulator layer are approximately 150 mm in length in the longitudinal direction of the power cable, and the strip shape having a width of 12.5 mm with the external semiconductive layer adhered to the insulator layer. And an exfoliation test of the external semiconductive layer with respect to the insulator layer was performed. In the peel test, for the strip-shaped sample, the external semiconductive layer was pulled from the insulator layer, and the force when peeled was measured as the peel force. The results are shown in Tables 1-2 . In addition, in Tables 1-2 , when peeling was not able to be performed, it indicated as "non-peeling".

From the results shown in Tables 1 and 2 , in the power cables of Examples 1 to 16, it was possible to easily peel the external semiconductive layer from the insulator layer .

  From this, it was confirmed that according to the power cable of the present invention, terminal processing can be performed efficiently.

DESCRIPTION OF SYMBOLS 1 ... Conductor, 2 ... Internal semiconductive layer, 3 ... Insulator layer, 4 ... External semiconductive layer, 10 ... Power cable.

Claims (2)

Conductors,
An insulating layer that is formed by extruding a resin composition for an insulating layer containing polyethylene and is crosslinked, and surrounds the conductor;
An external semiconductive layer formed by extruding a resin composition for an external semiconductive layer containing a polymer and a conductive material so as to cover the insulator layer, and then crosslinking,
Both the resin composition for an insulator layer and the resin composition for an external semiconductive layer contain an imidazole compound ,
In the resin composition for an insulator layer, the imidazole compound is blended at a ratio of 0.02 to 0.3 parts by mass with respect to 100 parts by mass of the polyethylene,
The external semiconductive layer resin composition contains the imidazole compound in a proportion of 0.02 to 0.3 parts by mass with respect to 100 parts by mass of the polymer .
Power cable characterized by The power cable according to claim 1, further comprising an internal semiconductive layer provided between the conductor and the insulator.

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