JP5367480B2 - Power cable - Google Patents

Description

The present invention relates to a power cable .

There is an insulated wire whose outer periphery is covered with an insulator. There are also known power cables in which this insulated wire is a power line core and this is covered with a sheath, and power cables in which this insulated wire is a power line core and a plurality of bundles are covered with a sheath. Furthermore, there are double-line power cables in which a plurality of these insulated wires and single-line power cables are bundled.
Hereinafter, in the present invention, the term “power line core” is used to include an insulated wire.

  In addition, recycled material mixing that mixes recycled material (cross-linked polyolefin waste) used for insulation of insulated wires and cables, etc. so that it can be thermoplasticized, and non-recycled polyolefin resin (for example, virgin material) A technique for forming an insulator again with a resin is known (see, for example, Patent Document 1).

  Further, in order to identify a plurality of power line cores of the power cable, there is a method of applying a paint to the surface of the insulator and coloring it. Further, there is a method in which a pigment is mixed with an insulating material to color all the insulators. Furthermore, it has also been proposed that the insulator is made into two layers and only the outer layer is colored by mixing a pigment with the insulating material of the outer layer (see, for example, Patent Document 2).

JP 2006-66262 A JP 2002-324443 A

  By the way, since the colored material such as the waste material added with carbon black is mixed in the recycled material mixed resin, the recycled material mixed resin becomes black. For this reason, when the recycled material mixed resin is used, it is difficult to identify all the insulators by coloring them.

  Therefore, it is conceivable to use two layers of insulators, color only the outer layer, and use a recycled material mixed resin for the inner layer. However, if the thickness of the outer layer is thin, the color becomes unclear due to the effect that the inner layer is colored with a pigment such as carbon black, and the discrimination is reduced. For this reason, there is a possibility that the identification of the power line core may be misidentified in a manhole or a building where the connection work of the power cable is performed.

The subject of this invention is improving the discriminability of the power cable in which the insulator was formed with the recycled material mixed resin.

The invention according to claim 1 is a power cable having a plurality of power line cores composed of a conductor and an insulator covering the conductor, wherein the insulator is formed of a recycled material mixed resin provided on an outer peripheral portion of the conductor. The first insulating layer formed and a second insulating layer having a different color from the first insulating layer provided on the outer periphery of the first insulating layer, and the second insulating layer of at least one power line core is The second insulating layer of the other power line core is a color other than red, and the red second insulating layer is thicker than the second insulating layers of other colors.
The red second insulating layer may have a thickness of 0.15 mm or more.
Further, the thickness of the second insulating layer of a color other than red may be 0.10 mm or more.

ADVANTAGE OF THE INVENTION According to this invention, a power cable with favorable discrimination can be provided.

It is sectional drawing which shows 1 A of electric power cables which concern on the 1st Embodiment of this invention. It is sectional drawing which shows the power cable 1B which concerns on the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
[First Embodiment]
FIG. 1 is a cross-sectional view showing a power cable 1A according to the first embodiment of the present invention. As shown in FIG. 1, the power cable 1 </ b> A is generally configured by a power line core 10 and a sheath 20 that covers the power line core 10.
The power line core 10 includes a conductor 11 and an insulator 12 that covers the conductor 11. For the conductor 11, for example, a copper wire, an aluminum wire or the like can be used.
For the sheath 20, for example, vinyl chloride or the like can be used.

  The insulator 12 includes an inner layer 13 (first insulating layer) and an identification layer 14 (second insulating layer). The inner layer 13 forms most part of the insulator 12. For the inner layer 13, a recycled material mixed resin obtained by mixing a recycled material obtained by regenerating a crosslinked polyolefin (system) waste material so as to be thermoplasticized and a polyolefin (system) resin that is not a recycled material is used.

  The cross-linked polyolefin (system) waste material is a waste material of the cross-linked polyolefin (system) resin. Examples of the cross-linked polyolefin (system) waste include coating waste of wiring materials such as wire coating waste, pipes for water supply, hot water supply, indoor heating, and various foams discarded as general waste. . Regardless of the age of the collected waste, there is no problem even if it is extremely deteriorated.

Here, the term “polyolefin (based) resin” is used to mean including polyolefin resin and polyolefin based resin.
Examples of the polyolefin resin include high density polyethylene, linear low density polyethylene, low density polyethylene, and polypropylene.
Examples of the polyolefin resin include ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid ester copolymer, ethylene- (meth) acrylic acid copolymer, and the like.

  The cross-linked polyolefin resin is obtained by cross-linking one or more resins selected from polyolefin resins or polyolefin resins. The cross-linked polyolefin (based) resin may be obtained by any cross-linking method. For example, a cross-linked polyolefin resin using a cross-linking agent such as an organic peroxide or a silane compound, a cross-linked one using an electron beam, or the like can be used. .

Here, an example of a method for regenerating the crosslinked polyolefin (system) waste material so that it can be thermoplasticized into a recycled material will be described.
First, the cross-linked polyolefin (system) waste material is put into the same-direction meshing twin-screw extruder, and the cross-linking is cut (thermoplastic treatment) to obtain a recycled material.

  The gel fraction of the recycled material that has been subjected to the thermoplastic treatment is preferably 40% or less, and more preferably 10% or less. Here, the gel fraction is a ratio of the mass of the sample that remains without being dissolved in the heated xylene to the mass of the original sample. The gel fraction can be measured by “4.25 degree of crosslinking” in JIS C 3005.

By performing the thermoplastic treatment under the appropriate conditions with the same-direction meshing twin screw extruder, the gel fraction of the recycled material can be reduced to 40% or less. A preferable processing temperature is 250 ° C. to 400 ° C., and a preferable shear rate is 200 sec ⁻¹ or more. Here, the shear rate is a numerical value obtained by dividing the peripheral speed (mm / s) of the outermost peripheral part of the screw element of the same-direction meshing twin-screw extruder by the clearance (mm) between the screw and the barrel.

  Next, the obtained recycled material is mixed with a polyolefin (based) resin that is not a recycled material to obtain a recycled material mixed resin. The mixing ratio of the recycled material is 50% by mass or less, preferably 40% by mass or less of the total resin amount. However, 0 mass% is not included.

  As the polyolefin (based) resin that is not a recycled material, various resins can be used as long as they have not been cross-linked, but a resin that has never been molded after production (so-called virgin material) is preferable. Used for. As the polyolefin (based) resin that is not a recycled material, one kind or a mixture of two or more kinds of polyolefin resins or polyolefin resins can be used. Among these, it is preferable to use high density polyethylene, linear low density polyethylene, and low density polyethylene.

  The identification layer 14 is formed outside the inner layer 13. The identification layer 14 is made of a polyolefin (based) resin (hereinafter referred to as an identification resin) colored in red, white, green, blue, or the like. Here, white means an achromatic color or a saturation of 2 or less and a lightness of 7 or more in the Munsell color system (JIS Z 8721, a method for displaying colors by three attributes). Similarly, red means hue R, lightness 3 or more and saturation 8 or more, green means hue G, lightness 4 or more and saturation 6 or more, and blue means hue B, lightness 4 or more and saturation 6 or more.

  The polyolefin (based) resin used for the identification layer 14 may be any material as long as the intended color clearly appears.

  The thickness of the identification layer 14 is preferably 0.10 mm or more. The inner layer 13 made of the recycled material mixed resin is often black as a whole. For this reason, when the thickness of the identification layer 14 is less than 0.10 mm, the color of the identification layer 14 becomes unclear due to the influence of the color of the inner inner layer 13.

  Furthermore, the thickness of the identification layer 14 is preferably thicker than 0.10 mm depending on the color of the identification layer 14. For example, if the identification layer 14 is red, the thickness is preferably 0.15 mm or more. When the thickness of the identification layer 14 is 0.10 mm or more for other colors, the color is clear. However, when the identification layer 14 is red, the thickness of the identification layer 14 is less than 0.15 mm. The red color of the identification layer 14 is unclear. By setting the thickness of the red identification layer 14 to 0.15 mm or more, the red color can be made clear.

  Additives used to form a normal insulating layer can be used for the recycled material mixed resin and the identifying resin. Specifically, an appropriate amount of a crosslinking agent, a crosslinking aid, an antioxidant, an ultraviolet absorber, and the like can be added as necessary.

  The above recycled material mixed resin is put into the hopper of the first extruder, the identifying resin is put into the hopper of the second extruder, and both are connected by a crosshead. The recycled material mixed resin and the identifying resin are It is extruded around the conductor 11 and cross-linked. What is necessary is just to select a normal crosslinking method suitably as a crosslinking method. For example, “peroxide crosslinking method” in which an organic peroxide is added to the recycled material mixed resin and the identifying resin and extruded around the conductor 11, and the silane compound is added to the recycled material mixed resin and the identified resin. Examples include a “silane crosslinking method” in which a crosslinking aid is added and extruded around the conductor 11 and then crosslinked with moisture, an “electron beam crosslinking method” by electron beam irradiation, and the like.

  As described above, the power line core 10 in which the insulator 12 including the inner layer 13 and the identification layer 14 is formed on the outer peripheral portion of the conductor 11 is formed. Thereafter, the power cable 1 </ b> A is completed by covering the power line core 10 with the sheath 20.

  In the power cable 1A manufactured in this way, since the identification layer 14 is provided only on the surface of the insulator 12, most of the inner layer 13 can be formed, and more recycled material can be used.

  In the above embodiment, the insulator 12 is directly formed on the outer peripheral portion of the conductor 11, but another layer such as a semiconductive layer may be formed between the conductor 10 and the insulator 12.

[Second Embodiment]
FIG. 2 is a sectional view showing a power cable 1B according to the second embodiment of the present invention. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is omitted.
The power cable 1B is formed by individually covering four power line cores 10B, 10W, 10G, and 10R with a sheath 20. The identification layer 14B of the power line core 10B is colored blue, the identification layer 14W of the power line core 10W is white, the identification layer 14G of the power line core 10G is green, and the identification layer 14R of the power line core 10R is colored red.

In the present embodiment, the red identification layer 14R is thicker than the other color identification layers 14B, 14W, and 14G. The thickness of the identification layers 14B, 14W, and 14G is preferably 0.10 mm or more. In addition, the thickness of the identification layer 14R is preferably 0.05 mm or more thicker than the thickness of the identification layers 14B, 14W, and 14G. By making the thickness of the identification layer 14R 0.05 mm or more thicker than the thickness of the identification layers 14B, 14W, and 14G, the red color discrimination can be made comparable to other colors. Specifically, it is preferable that the identification layers 14B, 14W, and 14G have a thickness of 0.10 mm and the identification layer 14R has a thickness of 0.15 mm.
Hereinafter, examples of the present invention will be described in more detail.

(Recycled materials)
A cross-linked polyethylene electric wire for outdoor use was selected from the removed insulated electric wire, and further, a cross-linked waste material mainly selected by organic peroxide was selected and pulverized to 10 mm or less. Note that, even after sorting, the wire covering waste material slightly cross-linked by a method other than the organic peroxide cross-linking is also mixed.
The above-mentioned cross-linked polyethylene wire covering waste material was put into a co-directional meshing type twin screw extruder, and subjected to a thermoplastic treatment at a processing temperature of 300 ° C. and a shear rate of 2200 to 2300 sec ⁻¹ to obtain a recycled material.

(Measurement of gel fraction of recycled material)
The gel fraction was measured in accordance with a conventional method by placing a sample in heated xylene, measuring the mass of the sample that remained without being dissolved, and determining the ratio of this to the mass of the sample before the test as the gel fraction. The specific method was based on “4.25 degree of crosslinking” in JIS C 3005. The measurement results are as shown in Table 1.
(Polyolefin (based) resin (virgin material) that is not recycled)
Polyethylene resin (NUCG 9301, manufactured by Dow Chemical Co., Ltd.) was used.
(Recycled material mixed resin)
The recycled material and the virgin material were mixed to obtain a recycled material mixed resin. In Examples 1, 2, 6, 7, 8, and Comparative Examples 1 and 3, 50 parts by mass of the virgin material was mixed with 50 parts by mass of the recycled material. In Examples 3, 4, 5 and Comparative Example 2, 70 parts by mass of virgin material was mixed with 30 parts by mass of recycled material.

(Identification resin)
As a pigment for the virgin material, 10 parts by mass of PEM F940587R (red), PEM F172W (white) and PEM F387G (green) manufactured by Dainichi Seika Kogyo Co., Ltd. are respectively mixed with 100 parts by mass of the virgin material. A green identifying resin was obtained.

(Manufacture of power cables)
A recycled material mixed resin, a silane solution (A-171, manufactured by Nihon Unicar), and a catalyst master batch (Moldex CM846, manufactured by Apco Corporation) were charged into a hopper of a 120 mm diameter single screw extruder. The input amount of the silane liquid was 2.3 parts by mass with respect to 100 parts by mass of the regenerated material mixed resin, and the input amount of the catalyst master batch was 5 parts by mass with respect to 100 parts by mass of the regenerated material mixed resin. The mixing zone was set to 180 ° C. or lower, the graft reaction zone was set to 220 ° C. or lower, and the screw rotation speed was set to 10 rpm.
Further, an identification resin was put into a hopper of a 50 mm diameter single screw extruder connected to the above extruder by a cross head.

Next, the recycled material mixed resin is extruded to a thickness of 1 mm on the outer periphery of a copper conductor having a cross-sectional area of 14 mm ² , and the identification resin is extruded to the outer periphery of the recycled material mixed resin to have the thickness shown in Table 1. It was.
Then, the manufactured insulated wire was immersed in an 80 degreeC warm water bath for 24 hours, and the crosslinking process was performed.

(Vividness evaluation)
It was evaluated by the Munsell color system (JIS Z 8721 color display method-color display by three attributes). The evaluation criteria were set at a level that would not cause misidentification of the power line core even in places where temporary lighting was performed with incandescent lamps in manholes or buildings where cable connection work was performed.
Specifically, it was judged by visual comparison with a vertical section of a Munsell color solid. For red, a lightness of 3 or more and a saturation of 8 or more was “good”, and a lightness of 2 or less or a saturation of 7 or less was “bad”. For green, a lightness of 4 or more and a saturation of 6 or more was “good”, and a lightness of 3 or less or a saturation of 5 or less was “bad”. For white, an achromatic color or a saturation of 2 or less, a brightness of 7 or more was “good”, and a brightness of 6 or less was “bad”. The evaluation results are shown in Table 1.

When the color of the identification layer was white or green, the sharpness was poor when the thickness of the identification layer was 0.05 mm (Comparative Examples 2 and 3). On the other hand, when the thickness of the identification layer was 0.10 mm or more, the sharpness was good (Examples 3 to 8).
On the other hand, when the color of the identification layer was red, the sharpness was poor even when the thickness of the identification layer was 0.10 mm. When the thickness of the identification layer was 0.15 mm or more, the sharpness was good (Examples 1 and 2).

  As described above, by making the thickness of the identification layer 0.10 mm or more, the sharpness of the identification layer can be improved. Furthermore, when the identification layer is red, the sharpness of the identification layer can be improved by setting the thickness to 0.15 mm or more. For this reason, it is possible to reduce the possibility of misidentification of the power line core in a manhole or building where the power cable connection work is performed.

  In the above embodiment, the red, white, and green identification layers have been described. However, the present invention is not limited to this, and the thickness of the identification layer is not less than 0.10 mm for blue and other colors (except for red). By doing so, the sharpness of the identification layer can be improved.

1A, 1B Power cable 10, 10B, 10W, 10G, 10R Power line core 11 Conductor 12 Insulator 13 Inner layer 14, 14B, 14W, 14G, 14R Identification layer 20 Sheath

Claims (3)

In a power cable having a plurality of power lines consisting of a conductor and an insulator covering the conductor,
The insulator includes a first insulating layer provided on the outer peripheral portion of the conductor and formed of a recycled material mixed resin, and a second color different from the first insulating layer provided on the outer peripheral portion of the first insulating layer. Consisting of an insulating layer,
The second insulating layer of at least one power line core is red, the second insulating layer of the other power line core is a color other than red, and the red second insulating layer is a second insulating layer of another color A power cable characterized by being thicker than.   The power cable according to claim 1, wherein the red second insulating layer has a thickness of 0.15 mm or more.   The power cable according to claim 1 or 2, wherein a thickness of the second insulating layer of a color other than red is 0.10 mm or more.

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