JP2018045885A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of obtaining high insulation properties and high flame retardancy and achieving reduction in a diameter in an insulated wire.SOLUTION: An insulated wire has a conductor and a coating layer arranged on the outer periphery of the conductor, where the coating layer has a semiconductive layer which is arranged on the outer periphery of the conductor, and is formed of a polymer composition containing a conductive agent and having volume resistivity of 1×10Ωcm or less, a high electric insulating layer which is arranged on the outer periphery of the semiconductive layer and is formed of a polymer composition having volume resistivity of 1×10Ωcm or more, and a flame retardant layer which is arranged on the outer periphery of the high electric insulation layer and is formed of a polymer composition containing a flame retardant, where each thickness of the high electric insulating layer and the semiconductive layer is thinner than a thickness of the flame retardant layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an insulated wire.

  Insulated wires used as wiring for railway vehicles, automobiles, and the like are required not only to have insulation properties but also to have flame resistance that is difficult to burn in the event of a fire. Therefore, a flame retardant is mix | blended with the coating layer of an insulated wire. For example, Patent Document 1 discloses an insulated wire in which a coating layer is formed by laminating a flame retardant layer containing a flame retardant on the outer periphery of an insulating layer having an insulating property.

JP 2010-97881 A

  In recent years, for example, from the viewpoint of weight reduction, the diameter of an insulated wire is required to be reduced. However, it is not easy to obtain a high insulating property and high flame retardancy and to reduce the diameter.

  One object of the present invention is to provide a technique capable of obtaining high insulation and high flame retardancy and reducing the diameter of an insulated wire.

According to one aspect of the invention,
Conductors,
A coating layer disposed on the outer periphery of the conductor;
Have
The coating layer is
A semiconductive layer formed of a polymer composition (A) disposed on the outer periphery of the conductor and containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less;
A high electrical insulating layer formed of a polymer composition (B) disposed on the outer periphery of the semiconductive layer and having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more;
A flame retardant layer formed of a polymer composition (C) including at least a flame retardant disposed on an outer periphery of the high electrical insulating layer;
Have
An insulated wire is provided in which the high electrical insulating layer and the semiconductive layer are thinner than the flame retardant layer, respectively.

  ADVANTAGE OF THE INVENTION According to this invention, in an insulated wire, high insulation and high flame retardance can be obtained, and diameter reduction can be achieved.

It is sectional drawing perpendicular | vertical to the length direction of the insulated wire which concerns on one Embodiment of this invention. It is sectional drawing perpendicular | vertical to the length direction of the insulated wire which concerns on other embodiment. It is sectional drawing perpendicular | vertical to the length direction of the conventional insulated wire.

  The inventors of the present invention have studied the structure of an insulated wire that can achieve high insulation and high flame retardancy and can be reduced in diameter.

  First, the conventional wire structure will be described, and the concept of the wire structure in the embodiment of the present invention will be described. FIG. 3 is a cross-sectional view perpendicular to the length direction of a conventional insulated wire.

  The insulated wire 200 having a conventional structure includes a conductor 210, an insulating layer 220 disposed on the outer periphery of the conductor 210, and a flame retardant layer 230 disposed on the outer periphery of the insulating layer 220 and blended with a flame retardant.

  In the insulated wire 200 having a conventional structure, the polymer composition forming the insulating layer 220 is provided with a certain amount of flame retardant additive (for example, for imparting a certain amount of flame resistance to the insulating layer 220 itself (for example, Inorganic fillers such as calcium carbonate and clay).

The insulating property of the polymer composition forming the insulating layer 220 is lower than the insulating property of the base polymer of the polymer composition due to the blending of flame retardant additives and the like. For example, when polyethylene is used as the base polymer of the polymer composition forming the insulating layer 220, a volume resistivity of the base polymer on the order of about 1 × 10 ¹⁶ Ωcm can be obtained. When the flame retardant additive or the like is blended in the polymer composition, the volume resistivity of the polymer composition forming the insulating layer 220 is reduced to an order of about 1 × 10 ¹⁴ Ωcm, for example.

  The present inventors studied to make the flame retardant layer 230 thinner in order to reduce the diameter of the insulated wire 200. However, the high flame resistance of the insulated wire 200 cannot be obtained simply by thinning the flame retardant layer 230 (without changing the thickness of the insulating layer 220).

  Therefore, it was studied to make the insulating layer 220 thin. However, high insulation of the insulated wire 200 cannot be obtained simply by making the insulating layer 220 thin. For this reason, the amount of the flame retardant additive and the like added to the insulating layer 220 is suppressed, and the insulating property of the polymer composition forming the insulating layer 220 is brought close to the high insulating property of the base polymer, thereby achieving a desired level. It was studied to reduce the thickness of the insulating layer 220 required to obtain insulation.

  However, the conductor 210 has a twisted wire structure in which strands are twisted and has irregularities on the surface. For this reason, the insulating layer 220 is easily broken due to electric field concentration caused by unevenness on the surface of the conductor 210, and it is necessary to make the insulating layer 220 thick to some extent in order to improve withstand voltage characteristics. Can not.

  Therefore, while using an insulating layer in which the amount of flame retardant additives and the like is suppressed, a semiconductive layer containing a conductive agent is provided inside the insulating layer (on the conductor side) and immediately above the conductor. The arranged new structure was examined. The insulating layer in which the blending amount of the flame retardant additive or the like is suppressed is referred to as a “high electrical insulating layer”.

  According to such a structure, by using a high electrical insulating layer in which the blending amount of the flame retardant additive or the like is suppressed and the insulating property is increased (decrease in insulating property is suppressed), a desired electrical insulation layer is used. The thickness of the high electrical insulation layer for obtaining insulation can be reduced. In addition, the semiconductive layer functions as an uneven relief layer by covering the unevenness of the conductor surface, and the high electrical insulating layer disposed on the semiconductive layer can be thinned. Further, as the high electrical insulating layer that is easy to burn can be made thinner, the thickness of the flame retardant layer for obtaining desired flame retardance can also be reduced.

  The volume resistivity of the polymer composition forming the high electrical insulation layer is controlled by the volume resistivity of the polymer composition forming the original insulation layer 220 by suppressing the amount of the flame retardant additive and the like. Compared to, for example, it can be greatly improved to about 100 times. For this reason, it can be said that it is easier to make the insulating layer thinner while improving the volume resistivity while obtaining the desired insulating property than to make the flame retardant layer thinner.

  In this way, an electric wire structure that can achieve high insulation and high flame retardancy and can be reduced in diameter can be obtained.

  As a thin insulated wire to which such a wire structure is preferably applied, for example, one having an outer diameter (diameter) of 7 mm or less is assumed. The insulation of the insulated wire is evaluated by, for example, a direct current stability test as described later. The flame retardancy of an insulated wire is evaluated by, for example, a VFT test or a VTFT test as described later. Although the use of an insulated wire is not specifically limited, For example, a railway vehicle use, a motor vehicle use, a medical use, etc. are mentioned.

  Next, with reference to FIG. 1, the insulated wire 100 by one Embodiment of this invention is demonstrated. FIG. 1 is a cross-sectional view perpendicular to the length direction showing an example of the structure of the insulated wire 100.

<Configuration of insulated wire>
The insulated wire 100 includes a conductor 110 and a coating layer 120 disposed on the outer periphery of the conductor 110.

〔conductor〕
As the conductor 110, for example, a stranded wire in which a plurality of strands (metal wires) are twisted together can be used. As an element wire, an aluminum wire, a gold wire, a silver wire, etc. other than a copper wire and a copper alloy wire can be used, for example, and the thing which gave metal plating, such as tin and nickel, to the perimeter may be used. The outer diameter (diameter) of the conductor 110 is, for example, not less than 1 mm and not more than 6 mm. The outer diameter (diameter) of a strand is 0.1 mm or more and 0.5 mm or less, for example. The material, structure, dimensions, and the like of the conductor 110 can be appropriately selected according to the characteristics required for the conductor 110 in the insulated wire 100.

(Coating layer)
The covering layer 120 is disposed on the outer periphery of the semiconductive layer 130 disposed on the outer periphery of the conductor 110, the high electrical insulating layer 140 disposed on the outer periphery of the semiconductive layer 130, and the outer periphery of the high electrical insulating layer 140. It has a laminated structure 160 in which a flame retardant layer 150 is laminated.

(Semiconductive layer)
The semiconductive layer 130 is formed from a polymer composition (A) containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less. The semiconductive layer 130 is formed by, for example, extruding the polymer composition (A) onto the outer periphery of the conductor 110.

  Examples of the base polymer used in the polymer composition (A) include a polyolefin resin. As the polyolefin resin, for example, a polyethylene resin or the like can be used. Examples of the polyethylene resin include polyethylenes such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), and ethylene-ethyl acrylate. Copolymer, ethylene-methyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-butene copolymer, ethylene-butene-hexene terpolymer, ethylene-propylene-diene terpolymer (EPDM) ), Ethylene-octene copolymer (EOR), ethylene-propylene copolymer (EPR), ethylene-styrene copolymer, styrene-butadiene copolymer, and those modified with an acid such as maleic acid, etc. Can be used. A polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The base polymer used in the polymer composition (A) preferably contains, for example, EVA. EVA is preferable because it has a high filler receptivity, so it is easy to add a conductive agent, and the resin itself has a certain degree of flame retardancy. The EVA VA amount is preferably 15% or more from the viewpoint of filler acceptability, for example, and preferably 80% or less from the viewpoint of manufacturability such as adhesion.

  Examples of the conductive agent used in the polymer composition (A) include carbon black and carbon nanotubes. Preferably, for example, carbon black can be used. As carbon black, for example, furnace black, channel black, acetylene black, thermal black and the like can be used. Preferably, acetylene black can be used because high conductivity can be imparted in a small amount. A conductive agent may be used individually by 1 type, and may use 2 or more types together.

The blending amount of the conductive agent is not particularly limited as long as the volume resistivity of the polymer composition (A) forming the semiconductive layer 130 is 1 × 10 ⁹ Ωcm or less. For example, the compounding amount of carbon black with respect to 100 parts by mass of the base polymer is 30 parts by mass or more. Note that, for example, the mechanical properties of the semiconductive layer 130 may be deteriorated and the elongation rate may be lowered, so that the blending amount of the conductive agent is preferably not excessive. For example, the blending amount of carbon black with respect to 100 parts by mass of the base polymer is 150 parts by mass or less.

  The semiconductive layer 130 is preferably composed of a crosslinked polymer composition (A) in order to improve heat resistance. Examples of the crosslinking method include irradiation crosslinking, chemical crosslinking, and silane crosslinking. The polymer composition (A) may contain a crosslinking aid or a crosslinking agent in order to achieve good crosslinking. As will be described later, since the cross-linking of the high electrical insulating layer 140 is preferably irradiation cross-linking, the semiconductive layer is formed simultaneously with the irradiation cross-linking of the high electrical insulating layer 140, that is, in the same process as that of the high electrical insulating layer 140. It is efficient to crosslink 130 by irradiation.

  In addition, when the semiconductive layer 130 is comprised by the crosslinked polymer composition (A), the volume resistivity of a polymer composition (A) shows the volume resistivity of a crosslinked polymer composition (A). .

  The polymer composition (A) is within the range that does not impair the properties of the semiconductive layer 130, and, if necessary, other additives such as flame retardants, antioxidants, copper damage inhibitors, reinforcing agents, process oils, etc. It may contain.

(High electrical insulation layer)
The high electrical insulating layer 140 is formed from a polymer composition (B) having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more. The high electrical insulating layer 140 is formed, for example, by extruding the polymer composition (B) onto the outer periphery of the semiconductive layer 130.

Examples of the base polymer used in the polymer composition (B) include a polymer having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more, such as a polyolefin resin. As the polyolefin resin, for example, polyethylene such as LDPE, LLDPE, and HDPE can be used. A polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The base polymer used in the polymer composition (B) preferably contains, for example, polyethylene. Polyethylene is preferable because volume resistivity can be improved by crosslinking. As polyethylene, any of LDPE, LLDPE, and HDPE may be used. From the viewpoint of easy crosslinking, LDPE may be used.

  The high electrical insulating layer 140 is preferably composed of a crosslinked polymer composition (B) in order to improve the volume resistivity. Examples of the crosslinking method include irradiation crosslinking, chemical crosslinking, and silane crosslinking. The polymer composition (B) may contain a crosslinking aid or a crosslinking agent in order to achieve good crosslinking. However, irradiation crosslinking that does not require the addition of an additive is preferable from the viewpoint of not lowering the electrical insulation.

  When the high electrical insulating layer 140 is composed of a crosslinked polymer composition (B), the volume resistivity of the polymer composition (B) is the volume resistivity of the crosslinked polymer composition (B). Show.

Although it is preferable that the polymer composition (B) does not contain as much an additive as possible from the viewpoint of suppressing a decrease in volume resistivity, the volume resistivity can be maintained at 1 × 10 ¹⁶ Ωcm or more as necessary. In addition, various additives may be contained. Examples of the additive include an antioxidant and a copper damage inhibitor.

  From the viewpoint of suppressing the decrease in volume resistivity of the polymer composition (B), for example, calcium carbonate, clay, talc, silica, wollastonite, zeolite, diatomaceous earth, silica sand, pumice powder, slate It is preferable that inorganic fillers such as powder, alumina, aluminum sulfate, barium sulfate, lithopone, calcium sulfate, and molybdenum disulfide, and flame retardants such as metal hydroxides are not contained in the polymer composition (B).

(Flame retardant layer)
The flame retardant layer 150 is formed from a polymer composition (C) containing a flame retardant. The flame retardant layer 150 is formed by, for example, extruding the polymer composition (C) on the outer periphery of the high electrical insulating layer 140.

  Examples of the base polymer used in the polymer composition (C) include polyolefin resins. As the polyolefin resin, for example, a polyethylene resin or the like can be used. Examples of the polyethylene resin include polyethylene such as LDPE, LLDPE, HDPE, EVA, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-butene copolymer, Ethylene-butene-hexene terpolymer, ethylene-propylene-diene terpolymer (EPDM), ethylene-octene copolymer (EOR), ethylene-propylene copolymer (EPR), ethylene-styrene copolymer Polymers, styrene-butadiene copolymers, and those modified with an acid such as maleic acid can be used. A polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  The base polymer used in the polymer composition (C) preferably contains, for example, EVA. EVA is preferable because it has a high filler receptivity, so that it is easy to add a flame retardant, and the resin itself has a certain degree of flame retardancy. For example, the EVA VA content is preferably 15% or more from the viewpoint of filler acceptability, and is preferably 60% or less from the viewpoint of suppressing a decrease in low-temperature properties, for example.

  The flame retardant used in the polymer composition (C) is preferably a non-halogen flame retardant because it does not generate a toxic gas, and for example, a metal hydroxide can be used. Examples of the metal hydroxide that can be used include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and a metal hydroxide in which nickel is dissolved in these. A flame retardant may be used individually by 1 type and may use 2 or more types together.

  From the viewpoint of controlling the mechanical properties (balance between tensile strength and elongation) of the flame retardant layer 150, the flame retardant is a silane coupling agent, a titanate coupling agent, a fatty acid such as stearic acid, or a fatty acid salt such as stearate. The surface treatment is preferably performed with a fatty acid metal such as calcium stearate.

  It is preferable that the compounding quantity of a flame retardant is 100 to 250 mass parts with respect to 100 mass parts of base polymers. There exists a possibility that desired high flame retardance may not be acquired as a compounding quantity is less than 100 mass parts. If the blending amount exceeds 250 parts by mass, the mechanical properties of the flame retardant layer 150 may be reduced, and the elongation may be reduced.

  The flame retardant layer 150 is preferably composed of a crosslinked polymer composition (C) in order to improve flame retardancy and heat resistance. Examples of the crosslinking method include irradiation crosslinking, chemical crosslinking, and silane crosslinking. The polymer composition (C) may contain a crosslinking aid or a crosslinking agent in order to achieve good crosslinking. In addition, since the crosslinking of the high electrical insulating layer 140 is preferably irradiation crosslinking, the flame retardant layer 150 is also radiation crosslinked at the same time as the irradiation crosslinking of the high electrical insulating layer 140, that is, in the same process as the irradiation crosslinking of the high electrical insulating layer 140. Is efficient.

The flame retardant layer 150 is, for example, an electrical insulating layer having a volume resistivity of about 1 × 10 ¹⁴ Ωcm (1 × 10 ¹³ Ωcm or more, or 1 × 10 ¹⁴ Ωcm or more) of the polymer composition (C). When the flame retardant layer 150 is composed of a crosslinked polymer composition (C), the volume resistivity of the polymer composition (C) indicates the volume resistivity of the crosslinked polymer composition (C). .

  As long as the polymer composition (C) does not impair the properties of the flame retardant layer 150, other additives such as antioxidants, copper damage inhibitors, lubricants, inorganic fillers, compatibilizers are used as necessary. , Stabilizers, carbon black, colorants and the like.

(Laminated structure of coating layer)
Next, the laminated structure 160 of the semiconductive layer 130, the high electrical insulating layer 140, and the flame retardant layer 150 in the coating layer 120 will be further described.

  The high electrical insulating layer 140 is configured to be thinner than the flame retardant layer 150. As a result, the flammability of the laminated structure 160 caused by the high electrical insulating layer 140 can be easily suppressed by the flame retardant layer 150 to obtain high flame resistance, and the laminated structure 160 is thinned to reduce the diameter of the insulated wire 100. Can be planned. In addition, the flame retardant layer 150 can be made thinner as the high electrical insulating layer 140 that is easy to burn is made thinner.

In order to make the high electrical insulation layer 140 thin while obtaining high insulation, the volume resistivity of the polymer composition (B) forming the high electrical insulation layer 140 is preferably 1 × 10 ¹⁶ Ωcm or more, more preferably 1 × 10 ¹⁷ Ωcm or more. The upper limit of the volume resistivity of the polymer composition (B) is not particularly limited.

  From the viewpoint of reducing the diameter while obtaining high flame retardancy, the thickness of the high electrical insulating layer 140 is more preferably ½ or less of the thickness of the flame retardant layer 150. More preferably, it is 1/3 or less.

The semiconductive layer 130 is disposed immediately above the conductor 110 (in contact with the conductor 110), and functions as an unevenness reducing layer that suppresses electric field concentration by covering the unevenness of the surface of the conductor 110. As a result, the high electrical insulating layer 140 disposed on the semiconductive layer 130 can be thinned. In order to increase the conductivity of the semiconductive layer 130, the volume resistivity of the polymer composition (A) forming the semiconductive layer 130 is preferably 1 × 10 ⁹ Ωcm or less. The lower limit of the volume resistivity of the polymer composition (A) is not particularly limited.

  The semiconductive layer 130 only needs to cover the unevenness of the surface of the conductor 110 (it is sufficient that the concave portion is filled and the surface is smoothed), and the thickness of the semiconductive layer 130 is set to a desired thickness. Can do. Here, the thickness of the semiconductive layer 130 is expressed as the thickness on the convex part (the thinnest part) of the twist of the surface of the conductor 110, that is, the thickness outside the outer diameter of the conductor 110.

  If the semiconductive layer 130 is too thick, the diameter reduction and the flame retardance are hindered. For this reason, the thickness of the semiconductive layer 130 is preferably thinner than the flame retardant layer 150, more preferably ½ or less of the thickness of the flame retardant layer 150, and the thickness of the flame retardant layer 150 is More preferably, it is 1/3 or less.

  From the viewpoint of reducing the diameter while obtaining high flame retardancy, the thickness of the laminated portion of the semiconductive layer 130 and the high electrical insulation layer 140, that is, the thickness of the semiconductive layer 130 and the thickness of the high electrical insulation layer 140 Is more preferably thinner than the thickness of the flame retardant layer 150, and more preferably 2/3 or less of the thickness of the flame retardant layer 150.

  The high electrical insulation layer 140 is preferably 80% or more, more preferably 90% or more, more preferably 95% or more of the voltage applied in the thickness direction of the laminated portion of the high electrical insulation layer 140 and the flame retardant layer 150. It is good that it is configured to share.

  Thereby, the voltage applied to the flame retardant layer 150 can be kept relatively low. The flame retardant layer 150 includes a large amount of additives such as a flame retardant, and the insulating property is more easily destroyed than the high electrical insulating layer 140. By keeping the voltage applied to the flame retardant layer 150 low, high insulation of the insulated wire 100 can be obtained.

In order to make the high electrical insulation layer 140 thin while making the high electrical insulation layer 140 share a voltage of 80% or more applied to the laminated portion of the high electrical insulation layer 140 and the flame retardant layer 150, The volume resistivity of the polymer composition (B) to be formed is preferably 1 × 10 ¹⁶ Ωcm or more, more preferably 1 × 10 ¹⁷ Ωcm or more.

  Further, in order to make the high electrical insulation layer 140 thin while allowing the high electrical insulation layer 140 to share a voltage of 80% or more applied to the laminated portion of the high electrical insulation layer 140 and the flame retardant layer 150, the high electrical insulation layer 140 is configured to be thin. The volume resistivity of the polymer composition (B) forming 140 is preferably 10 times or more, more preferably 50 times or more, more preferably the volume resistivity of the polymer composition (C) forming the flame retardant layer 150. Is preferably 100 times or more.

  From the viewpoint of a thin insulated wire, the outer diameter (diameter) of the insulated wire 100 is preferably 7 mm or less. The rated voltage (AC) of the insulated wire 100 is 3600 V or less, for example. Note that the small diameter also has an advantage that the semiconductive layer 130, the high electrical insulating layer 140, and the flame retardant layer 150 are easily cross-linked simultaneously by irradiation cross-linking.

  The upper limit of the thickness of the semiconductive layer 130 (on the convex portion of the twist of the surface of the conductor 110, that is, the thickness of the thinnest portion) is preferably, for example, 0.10 mm or less from the viewpoint of reducing the diameter. . The lower limit of the thickness of the semiconductive layer 130 is not particularly limited as long as the unevenness on the surface of the conductor 110 can be covered. However, for example, the thickness uniformity of the semiconductive layer 130 is improved and stable withstand voltage characteristics are obtained. From the viewpoint of obtaining, it is preferably 0.05 mm or more. In addition, it is preferable that the thickness of the portion filling the concave portion on the concave portion of the twist of the surface of the conductor 110 is not less than ½ of the outer diameter of the strand.

  The upper limit of the thickness of the high electrical insulating layer 140 is, for example, preferably 0.15 mm or less, and more preferably 0.10 mm or less, from the viewpoint of reducing the diameter. Note that the lower limit of the thickness of the high electrical insulation layer 140 is not particularly limited as long as desired insulation can be obtained. For example, the thickness of the high electrical insulation layer 140 can be increased by increasing the uniformity of the thickness, thereby providing stable insulation. From the viewpoint of obtaining, it is preferably 0.05 mm or more.

  About the upper limit of the thickness of the flame-resistant layer 150, it is preferable that it is 0.30 mm or less from a viewpoint of diameter reduction, for example. The lower limit of the thickness of the flame retardant layer 150 is not particularly limited as long as it is a thickness that provides flame retardancy according to the thickness of the high electrical insulating layer 140 (and the semiconductive layer 130). From the viewpoint of increasing the uniformity of the thickness of the flame retardant layer 150 and obtaining stable flame retardancy, the thickness is preferably 0.10 mm or more.

  From the viewpoint of reducing the diameter, it is preferable that no other layer is disposed between the semiconductive layer 130 and the high electrical insulating layer 140. That is, the high electrical insulating layer 140 is preferably disposed immediately above the semiconductive layer 130 (in contact with the semiconductive layer 130). Further, it is preferable that no other layer is disposed between the high electrical insulating layer 140 and the flame retardant layer 150. That is, it is preferable that the flame retardant layer 150 is disposed immediately above the high electrical insulation layer 140 (in contact with the high electrical insulation layer 140). Further, it is preferable that no other layer is disposed on the outer periphery of the flame retardant layer 150. That is, the flame retardant layer 150 is preferably the outermost layer of the covering layer 120, that is, the insulated wire 100.

  The semiconductive layer 130, the high electrical insulating layer 140, and the flame retardant layer 150 are preferably formed on the outer periphery of the conductor 110 by coextrusion. As a result, dust in the atmosphere that causes electric field concentration adheres to the boundary surface between the semiconductive layer 130 and the high electrical insulation layer 140 and the boundary surface between the high electrical insulation layer 140 and the flame retardant layer 150. Can be suppressed.

  Note that the semiconductive layer 130 may have a stacked structure of a plurality of semiconductive layers (sub-semiconductive layers) as necessary. Moreover, the high electrical insulating layer 140 may be configured by a stacked structure of a plurality of insulating layers (sub-insulating layers) as necessary. Moreover, the flame retardant layer 150 may be configured by a laminated structure of a plurality of flame retardant layers (sub flame retardant layers) as necessary.

  As described above, according to the present embodiment, the insulated wire can achieve high insulation and high flame retardancy and can be reduced in diameter.

  In addition, the insulated wire by embodiment is not restricted to use with an insulated wire single-piece | unit, You may use it in combination with another member as needed, such as using for the core of a cable.

<Other Embodiments of the Present Invention>
As mentioned above, although one embodiment of the present invention has been exemplarily and specifically described, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist thereof. For example, the following other embodiments are possible.

  With reference to FIG. 2, the insulated wire 100 by other embodiment is demonstrated. FIG. 2 is a cross-sectional view perpendicular to the length direction showing an example of the structure of an insulated wire 100 according to another embodiment.

  In another embodiment, the covering layer 120 disposed on the outer periphery of the conductor 110 includes the semiconductive layer 130, the flame retardant layer 150a disposed on the outer periphery of the semiconductive layer 130, and the outer periphery of the flame retardant layer 150a. A high electrical insulating layer 140 (on the outer periphery of the semiconductive layer 130 via the flame retardant layer 150a), and a flame retardant layer 150b disposed on the outer periphery of the high electrical insulating layer 140. A stacked structure 160 is stacked. The flame retardant layer 150 a and the flame retardant layer 150 b constitute the entire flame retardant layer 150.

  That is, in another embodiment, in addition to the flame retardant layer 150b disposed on the outside (opposite side of the conductor 110) of the high electrical insulation layer 140, the flame retardant layer 150 is disposed on the inside (conductor 110). The flame retardant layer 150a is disposed on the side). The flame retardant layer 150 a is formed from a polymer composition containing a flame retardant, similarly to the flame retardant layer 150 b, and is formed, for example, by extruding the polymer composition on the outer periphery of the semiconductive layer 130. For example, in order to further improve the flame retardancy, the flame retardant layer 150 having such a configuration may be used as necessary.

  Thus, the flame retardant layer 150 may be configured to be disposed only on the outside of the high electrical insulating layer 140, or may be configured to be disposed on both the outside and inside of the high electrical insulating layer 140. . However, in order to enhance the flame retardancy of the insulated wire 100, the flame retardant layer 150 is preferably disposed at least on the outer side (outer periphery) of the high electrical insulating layer 140.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

[Production of insulated wires]
As Examples 1 to 3 and Comparative Examples 1 to 3, insulated wires having the laminated structure shown in FIG. 1 were produced as follows.

  A polymer composition (A) that forms a semiconductive layer, a polymer composition (B) that forms a high electrical insulating layer, and a polymer composition (C) that forms a flame retardant layer were prepared. The formulations of the polymer compositions (A) to (C) are shown in Tables 1 to 3, respectively.

  A conductor having an outer diameter of 1.23 mm (a twist of 37 tin-plated copper strands having an outer diameter of 0.18 mm) was prepared. A polymer composition (A), a polymer composition (B), and a polymer composition (C) are simultaneously extruded on the outer periphery of the conductor, and crosslinked by electron beam irradiation so that a semiconductive layer and a high electrical insulating layer are obtained. And the flame-resistant layer was formed and the insulated wire was produced.

  In the insulated wires of Examples 1 to 3 and Comparative Examples 1 to 3, the thicknesses of the semiconductive layer, the high electrical insulating layer, and the flame retardant layer were varied. In Comparative Example 1, no semiconductive layer was formed. Table 4 shows the thickness of each layer and the total coating thickness.

[Evaluation of insulated wires]
For the insulated wires of Examples 1 to 3 and Comparative Examples 1 to 3, the insulating properties (electric properties) and flame retardancy were evaluated as follows. The evaluation results are shown in Table 4.

(DC stability test)
The electrical characteristics of the insulated wire, that is, the insulation reliability, was evaluated by a direct current stability test in which a direct current of 300 V was applied in an aqueous solution of 3% NaCl at 85 ° C. according to EN50305.6.7. Those that do not short-circuit in 10 days, that is, those in which the time until short-circuiting is 240 hours or more are passed (O), and those that are short-circuited in less than 10 days, that is, the time until short-circuiting is less than 240 hours Things were rejected (x).

(Flame retardance)
The flame retardancy of the insulated wire was evaluated by the vertical combustion test (VFT test and VTFT test) shown below.

  A VFT test was performed in accordance with a vertical flame propagation for a single insulated wire or cable specified in EN60332-1-2. Specifically, an insulated wire having a length of 600 mm was held vertically, and a flame was applied to the insulated wire for 60 seconds. After removing the flame, the fire extinguished within 60 seconds was accepted (◯), and the fire extinguished within 60 seconds was rejected (x).

  A VTFT test was conducted in accordance with a multi-cable cable vertical combustion test (Flame propagation (bunched cables)) defined in EN50266-2-4. Specifically, seven insulated wires with a total length of 3.5 m are twisted to form one bundle, 11 bundles are arranged vertically at equal intervals, burned for 20 minutes, and after self-extinguishing, the carbonization length from the lower end is measured. . If the carbonization length was 2.5 m or less, it was judged as pass (◯), and if the carbonization length was over 2.5 m, it was judged as failure (x).

(Comprehensive evaluation)
For the insulated wires that passed both the direct current stability test and the flame retardancy, the overall evaluation was passed (O), and for the other insulated wires, the overall evaluation was rejected (X).

<Example 1 to Example 3>
In Example 1, the thickness of the semiconductive layer is 0.10 mm, the thickness of the high electrical insulating layer is 0.11 mm, and the thickness of the flame retardant layer is 0.29 mm. In Example 2, the thickness of the semiconductive layer is 0.05 mm, the thickness of the high electrical insulating layer is 0.15 mm, and the thickness of the flame retardant layer is 0.30 mm. In Example 3, the thickness of the semiconductive layer is 0.10 mm, the thickness of the high electrical insulating layer is 0.08 mm, and the thickness of the flame retardant layer is 0.29 mm.

  In Example 1 to Example 3, the thickness of the high electrical insulating layer is thinner than the thickness of the flame retardant layer, and the thickness of the semiconductive layer is thinner than the thickness of the flame retardant layer. Compatibility and narrow diameter. In addition, since the semiconductive layer is formed, good insulating properties are obtained.

  The thickness of the high electrical insulation layer is 1/2 or less of the thickness of the flame retardant layer in Examples 1 to 3, and is 1/3 or less of the thickness of the flame retardant layer in Example 3. . In Examples 1 to 3, the thickness of the semiconductive layer is ½ or less of the thickness of the flame retardant layer, and in Example 2 is １ ／ or less of the thickness of the flame retardant layer. The sum of the thickness of the semiconductive layer and the thickness of the high electrical insulating layer is thinner than the thickness of the flame retardant layer in Examples 1 to 3, and the thickness of the flame retardant layer in Examples 2 and 3. 2/3 or less. In Example 3, the thickness of the high electrical insulating layer is thinner than the thickness of the semiconductive layer.

<Comparative Examples 1 to 3>
In Comparative Example 1, the semiconductive layer is not formed, the thickness of the high electrical insulating layer is 0.11 mm, and the thickness of the flame retardant layer is 0.4 mm. In Comparative Example 2, the thickness of the semiconductive layer is 0.10 mm, the thickness of the high electrical insulating layer is 0.20 mm, and the thickness of the flame retardant layer is 0.20 mm. In Comparative Example 3, the thickness of the semiconductive layer is 0.20 mm, the thickness of the high electrical insulating layer is 0.10 mm, and the thickness of the flame retardant layer is 0.20 mm.

  In Comparative Example 1, although the high electrical insulating layer is thin and the flame retardancy is good, the insulating property is unacceptable because the semiconductive layer is not formed.

  Although Comparative Example 2 and Comparative Example 3 passed the insulation because a semiconductive layer was formed, Comparative Example 2 had a thickness of the high electrical insulating layer equal to the thickness of the flame retardant layer. In Example 3, the thickness of the semiconductive layer is equal to the thickness of the flame retardant layer, and the flame retardancy is rejected.

The thickness of each layer is the same as in Example 1, and the polymer composition (A) for forming the semiconductive layer, the polymer composition (B) for forming the high electrical insulating layer, and the polymer for forming the flame retardant layer are used. Insulated wires of other examples in which the composition (C) is mixed in various ways are also produced, and the same characteristics as those of the above-described examples 1 to 3 are also obtained for these examples. For example, an insulated wire having a high electrical insulation layer using a polymer composition (B) having a volume resistivity of the order of 10 ¹⁶ Ωcm is produced, and the polymer composition (B) is 1 × 10 ¹⁶ Ωcm or more. Those having a volume resistivity of 5 can be used. In addition, for example, an insulated wire having a semiconductive layer using a polymer composition (A) on the order of a volume resistivity of 10 ⁸ Ωcm is manufactured, and the polymer composition (A) is 1 × 10 ⁹ Ωcm or less. Those having a volume resistivity of 5 can be used.

  As mentioned above, although this invention was demonstrated along embodiment, this invention is not restrict | limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

(Appendix 1)
Conductors,
A coating layer disposed on the outer periphery of the conductor;
Have
The coating layer is
A semiconductive layer formed of a polymer composition (A) disposed on the outer periphery of the conductor and containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less;
A high electrical insulating layer formed of a polymer composition (B) disposed on the outer periphery of the semiconductive layer and having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more;
A flame retardant layer formed of a polymer composition (C) including at least a flame retardant disposed on an outer periphery of the high electrical insulating layer;
Have
The high electric insulation layer and the semiconductive layer are insulated wires that are thinner than the flame retardant layer, respectively.

(Appendix 2)
The thickness of the high electrical insulating layer is more preferably 1/2 or less of the thickness of the flame retardant layer, and further preferably 1/3 or less of the thickness of the flame retardant layer. Insulated wire.

(Appendix 3)
The thickness of the semiconductive layer is more preferably 1/2 or less of the thickness of the flame retardant layer, and further preferably 1/3 or less of the thickness of the flame retardant layer. Insulated wires.

(Appendix 4)
The sum of the thickness of the semiconductive layer and the thickness of the high electrical insulating layer is preferably smaller than the thickness of the flame retardant layer, more preferably 2/3 or less of the thickness of the flame retardant layer. The insulated wire as described in any one of -3.

(Appendix 5)
The high electrical insulation layer is preferably 80% or more, more preferably 90% or more, more preferably 95% or more of the voltage applied in the thickness direction of the laminated portion of the high electrical insulation layer and the flame retardant layer. The insulated wire according to any one of supplementary notes 1-4,

(Appendix 6)
The polymer composition (B) is an insulated wire according to any one of appendices 1 to 5 having a volume resistivity of 1 × 10 ¹⁷ Ωcm or more.

(Appendix 7)
The volume resistivity of the polymer composition (B) forming the high electrical insulating layer is preferably 10 times or more, more preferably, the volume resistivity of the polymer composition (C) forming the flame retardant layer. The insulated wire according to any one of supplementary notes 1 to 6, which is 50 times or more, more preferably 100 times or more.

(Appendix 8)
The insulated wire according to any one of supplementary notes 1 to 7, wherein an outer diameter of the insulated wire is 7 mm or less.

(Appendix 9)
The thickness of the said semiconductive layer is an insulated wire as described in any one of the additional remarks 1-8 which is 0.10 mm or less.

(Appendix 10)
The insulated wire according to any one of supplementary notes 1 to 9, wherein the thickness of the high electrical insulating layer is preferably 0.15 mm or less, more preferably 0.10 mm or less.

(Appendix 11)
The thickness of the said flame-resistant layer is an insulated wire as described in any one of the additional remarks 1-10 which are 0.30 mm or less.

(Appendix 12)
The insulated wire according to any one of supplementary notes 1 to 11, wherein the semiconductive layer is disposed immediately above the conductor (in contact with the conductor).

(Appendix 13)
The insulated wire according to any one of appendices 1 to 12, wherein the high electrical insulating layer is disposed immediately above the semiconductive layer (in contact with the semiconductive layer).

(Appendix 14)
14. The insulated wire according to any one of supplementary notes 1 to 13, wherein the flame retardant layer is further disposed between the semiconductive layer and the high electrical insulating layer.

(Appendix 15)
The insulated flame according to any one of supplementary notes 1 to 14, wherein the flame retardant layer is disposed immediately above the high electrical insulation layer (in contact with the high electrical insulation layer).

(Appendix 16)
The said flame-retardant layer is an insulated wire according to any one of appendices 1 to 15, which is the outermost layer of the insulated wire.

(Appendix 17)
The insulated conductor according to any one of appendices 1 to 16, wherein the conductor is a stranded wire in which a plurality of strands are twisted together.

(Appendix 18)
The flame retardant layer according to any one of appendices 1 to 17, wherein the polymer composition (C) is an electrical insulating layer having a volume resistivity of 1 × 10 ¹³ Ωcm or more or 1 × 10 ¹⁴ Ωcm or more. Insulated wire.

100 Insulated wire 110 Conductor 120 Cover layer 130 Semiconductive layer 140 High electrical insulation layers 150, 150a, 150b Flame retardant layer 160 Laminated structure

Claims (3)

Conductors,
A coating layer disposed on the outer periphery of the conductor;
Have
The coating layer is
A semiconductive layer formed of a polymer composition (A) disposed on the outer periphery of the conductor and containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less;
A high electrical insulating layer formed of a polymer composition (B) disposed on the outer periphery of the semiconductive layer and having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more;
A flame retardant layer formed of a polymer composition (C) including at least a flame retardant disposed on an outer periphery of the high electrical insulating layer;
Have
The high electric insulation layer and the semiconductive layer are insulated wires that are thinner than the flame retardant layer, respectively.   2. The insulated wire according to claim 1, wherein a thickness of the high electrical insulating layer is ½ or less of a thickness of the flame retardant layer.   The insulated wire according to claim 1 or 2, wherein a thickness of the semiconductive layer is ½ or less of a thickness of the flame retardant layer.

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