JP6761587B2 - Insulated electric wires for railway vehicles - Google Patents

Description

The present invention relates to an insulated electric wire for a railway vehicle.

Insulated electric wires used as wiring for railway vehicles and automobiles are required to have not only insulating properties but also flame retardancy that makes them hard to burn in the event of a fire. Therefore, a flame retardant is blended in the coating layer of the insulated wire. For example, Patent Document 1 discloses an insulated wire in which a flame retardant layer containing a flame retardant is laminated on the outer periphery of an insulating layer having an insulating property to form a coating layer.

JP-A-2010-97881

In recent years, for example, from the viewpoint of weight reduction, it has been required to reduce the diameter of an insulated electric wire. However, it is not easy to obtain high insulation 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 electric wire for a railway vehicle.

According to one aspect of the invention
With the conductor
A coating layer arranged on the outer circumference of the conductor and
Have,
The coating layer is
A semi-conductive layer arranged on the outer periphery of the conductor and formed of the polymer composition (A) containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less,
A highly electrically insulating layer formed of the polymer composition (B) arranged on the outer periphery of the semi-conductive layer and having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more.
A flame retardant layer formed of the polymer composition (C) arranged at least on the outer periphery of the highly electrically insulating layer and containing a flame retardant, and
Have,
An insulated wire for a railway vehicle is provided in which the thicknesses of the highly electrically insulating layer and the semi-conductive layer are thinner than the thickness of the flame-retardant layer, respectively.

According to the present invention, it is possible to obtain high insulation and high flame retardancy and reduce the diameter of an insulated electric wire for a railway vehicle.

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

The present inventors have studied the structure of an insulated wire that can obtain high insulation and high flame retardancy and can reduce the diameter.

First, the conventional electric wire structure will be described, and the concept of the electric 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 the conventional insulated wire.

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

In the insulated wire 200 of the conventional structure, the polymer composition forming the insulating layer 220 is provided with an additive having (for example) flame retardancy (for example, to some extent) in order to impart a certain degree of flame retardancy to the insulating layer 220 itself. Inorganic fillers such as calcium carbonate and clay) are blended.

The insulating property of the polymer composition forming the insulating layer 220 is lower than that of the base polymer of the polymer composition due to the addition 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, the volume resistivity of the base polymer on the order of, for example, about 1 × 10 ¹⁶ Ωcm can be obtained. By adding a flame-retardant additive or the like to the polymer composition, the volume resistivity of the polymer composition forming the insulating layer 220 is reduced to the order of, for example, about 1 × 10 ¹⁴ Ωcm.

The present inventors have studied to make the flame-retardant layer 230 thinner in order to reduce the diameter of the insulated wire 200. However, simply thinning the flame-retardant layer 230 (without changing the thickness of the insulating layer 220) makes it impossible to obtain the high flame retardancy of the insulated wire 200.

Therefore, it was examined to make the insulating layer 220 thinner. However, simply thinning the insulating layer 220 makes it impossible to obtain the high insulating properties of the insulated wire 200. Therefore, it is desired to suppress the blending amount of the flame-retardant additive or the like to the insulating layer 220 and bring the insulating property of the polymer composition forming the insulating layer 220 closer to the high insulating property of the base polymer. It was examined to reduce the thickness of the insulating layer 220 required to obtain the insulating property.

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

Therefore, an insulating layer in which the amount of a flame-retardant additive or the like is suppressed is used, and a semi-conductive layer in which a conductive agent is blended is formed inside the insulating layer (on the conductor side) and directly above the conductor. We examined the new structure that was placed. An insulating layer in which the amount of a flame-retardant additive or the like is suppressed is referred to as a "high electrical insulating layer".

According to such a structure, it is desired to use a highly electrically insulating layer in which the blending amount of a flame-retardant additive or the like is suppressed and the insulating property is enhanced (the decrease in the insulating property is suppressed). The thickness of the highly electrically insulating layer for obtaining insulation can be reduced. Further, the semi-conductive layer functions as an unevenness-relieving layer by covering the unevenness of the conductor surface, and the highly electrically insulating layer arranged on the semi-conductive layer can be thinned. Further, as the highly electrically insulating layer that is easily combusted can be made thinner, the thickness of the flame-retardant layer for obtaining desired flame retardancy can be made thinner.

The volume resistivity of the polymer composition forming the high electrical insulating layer is the same as the volume resistivity of the polymer composition forming the original insulating layer 220 by suppressing the blending amount of the flame-retardant additive or the like. Compared with this, it can be significantly improved, for example, about 100 times. Therefore, it can be said that it is easier to thin the insulating layer while obtaining the desired insulating property by improving the volume resistivity as compared with thinning the flame-retardant layer.

In this way, an electric wire structure capable of obtaining high insulation and high flame retardancy and reducing the diameter can be obtained.

As a small-diameter 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 an insulated wire is evaluated, for example, by a DC 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. Insulated electric wires are used for railway vehicles.

Next, the insulated wire 100 according to the embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a cross-sectional view perpendicular to the length direction showing an example of the structure of the insulated wire 100.

<Structure of insulated wire>
The insulated wire 100 has a conductor 110 and a coating layer 120 arranged 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 can be used. As the strands, for example, in addition to copper wire and copper alloy wire, aluminum wire, gold wire, silver wire and the like can be used, and those having metal plating such as tin or nickel on the outer periphery may be used. The outer diameter (diameter) of the conductor 110 is, for example, 1 mm or more and 6 mm or less. The outer diameter (diameter) of the wire is, for example, 0.1 mm or more and 0.5 mm or less. The material, structure, dimensions, etc. 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 coating layer 120 is arranged on the semiconductive layer 130 arranged on the outer periphery of the conductor 110, the highly electrically insulating layer 140 arranged on the outer periphery of the semiconductive layer 130, and the outer periphery of the highly electrically insulating layer 140. It has a laminated structure 160 in which a flame-retardant layer 150 is laminated.

(Semi-conductive layer)
The semi-conductive layer 130 is formed from the polymer composition (A) containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less. The semi-conductive layer 130 is formed, for example, by 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 polyolefin resins and the like. As the polyolefin resin, for example, a polyethylene-based resin or the like can be used. Examples of the polyethylene-based resin include polyethylene 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. Copolymers, ethylene-methylacrylate copolymers, ethylene-glycidyl methacrylate copolymers, ethylene-butene copolymers, ethylene-butene-hexene ternary copolymers, ethylene-propylene-diene ternary copolymers (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. One type of polyolefin resin may be used alone, or two or more types may be used in combination.

The base polymer used in the polymer composition (A) preferably contains, for example, EVA. EVA is preferable because it has a high filler acceptability, so that a conductive agent can be easily added, and the resin itself has a certain degree of flame retardancy. The amount of VA of EVA is preferably, for example, 15% or more from the viewpoint of filler acceptability, and is 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, and preferably, for example, carbon black can be used. As the carbon black, for example, furnace black, channel black, acetylene black, thermal black and the like can be used, and preferably, acetylene black can be used because high conductivity can be imparted with a small amount. One type of conductive agent may be used alone, or two or more types may be used in combination.

The blending amount of the conductive agent is not particularly limited as long as the volume resistivity of the polymer composition (A) forming the semi-conductive layer 130 is 1 × 10 ⁹ Ωcm or less. For example, the blending amount of carbon black with respect to 100 parts by mass of the base polymer is 30 parts by mass or more. For example, the mechanical properties of the semi-conductive layer 130 may deteriorate and the elongation rate may decrease. Therefore, it is preferable that the amount of the conductive agent blended does not become 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 semi-conductive layer 130 is preferably composed of the crosslinked polymer composition (A) in order to improve heat resistance. Examples of the crosslinking method include irradiation crosslinking, chemical crosslinking, silane crosslinking and the like. The polymer composition (A) may contain a cross-linking aid or a cross-linking agent in order to carry out cross-linking well. As will be described later, since the cross-linking of the high electrical insulation layer 140 is preferably irradiation cross-linking, the semi-conductive layer is formed at the same time as the irradiation cross-linking of the high electrical insulation layer 140, that is, in the same process as the irradiation cross-linking of the high electrical insulation layer 140. It is efficient that 130 is also irradiated and crosslinked.

When the semi-conductive layer 130 is composed of the crosslinked polymer composition (A), the volume resistivity of the polymer composition (A) indicates the volume resistivity of the crosslinked polymer composition (A). ..

The polymer composition (A) may contain other additives such as flame retardant, antioxidant, copper damage inhibitor, reinforcing agent, process oil and the like, if necessary, as long as the characteristics of the semiconductive layer 130 are not impaired. May be contained.

(High electrical insulation layer)
The high electrical insulating layer 140 is formed from the 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 polymers having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more, such as polyolefin resin. As the polyolefin resin, for example, polyethylene such as LDPE, LLDPE, HDPE can be used. One type of polyolefin resin may be used alone, or two or more types may be used in combination.

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

The high electrical insulating layer 140 is preferably composed of the crosslinked polymer composition (B) in order to improve the volume resistivity. Examples of the crosslinking method include irradiation crosslinking, chemical crosslinking, silane crosslinking and the like. The polymer composition (B) may contain a cross-linking aid or a cross-linking agent in order to carry out cross-linking well. However, from the viewpoint of not lowering the electrical insulation property, irradiation cross-linking that does not require the addition of additives is preferable.

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

The polymer composition (B) is preferably free of additives as much as possible from the viewpoint of suppressing a decrease in volume resistivity, but is required as long as the volume resistivity can be maintained at 1 × 10 ¹⁶ Ωcm or more. Therefore, various additives may be contained. Examples of the additive include an antioxidant, a copper damage inhibitor, and the like.

From the viewpoint of suppressing the decrease in the volumetric resistance of the polymer composition (B), for example, calcium carbonate, clay, talc, silica, wollastonite (wollastonite), zeolite, diatomaceous soil, silica sand, pebbles, slate It is preferable that the polymer composition (B) does not contain an inorganic filler such as powder, alumina, aluminum sulfate, barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, or a flame retardant such as metal hydroxide.

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

Examples of the base polymer used in the polymer composition (C) include polyolefin resins and the like. As the polyolefin resin, for example, a polyethylene-based resin or the like can be used. Examples of the polyethylene-based resin include polyethylene such as LDPE, LLDPE, and HDPE, EVA, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, and ethylene-butene copolymer. Ethylene-butene-hexene ternary copolymer, ethylene-propylene-diene ternary copolymer (EPDM), ethylene-octene copolymer (EOR), ethylene-propylene copolymer (EPR), ethylene-styrene copolymer Combined products, styrene-butadiene copolymers, and those modified with an acid such as maleic acid can be used. One type of polyolefin resin may be used alone, or two or more types may be used in combination.

The base polymer used in the polymer composition (C) preferably contains, for example, EVA. EVA is preferable because it has a high filler acceptability, so that a flame retardant can be easily added, and the resin itself has a certain degree of flame retardancy. The amount of EVA VA 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.

As the flame retardant used in the polymer composition (C), a non-halogen flame retardant is preferable because it does not generate toxic gas, and for example, a metal hydroxide can be used. As the metal hydroxide, for example, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and a metal hydroxide in which nickel is dissolved in these can be used. One type of flame retardant may be used alone, or two or more types may be used in combination.

The flame retardant is a silane coupling agent, a titanate-based coupling agent, a fatty acid such as stearic acid, or a fatty acid salt such as stearic acid, from the viewpoint of controlling the mechanical properties (balance between tensile strength and elongation) of the flame retardant layer 150. , It is preferable that the surface is treated with a fatty acid metal such as calcium stearate.

The blending amount of the flame retardant is preferably 100 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the base polymer. If the blending amount is less than 100 parts by mass, the desired high flame retardancy may not be obtained. If the blending amount exceeds 250 parts by mass, the mechanical properties of the flame-retardant layer 150 may deteriorate and the elongation rate may decrease.

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, silane crosslinking and the like. The polymer composition (C) may contain a cross-linking aid or a cross-linking agent in order to carry out cross-linking well. Since the cross-linking of the high electrical insulation layer 140 is preferably irradiation cross-linking, the flame retardant layer 150 is also cross-linked at the same time as the irradiation cross-linking of the high electrical insulation layer 140, that is, in the same process as the irradiation cross-linking of the high electrical insulation layer 140. Is efficient.

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

The polymer composition (C) contains other additives such as antioxidants, copper damage inhibitors, lubricants, inorganic fillers, and compatibilizers, if necessary, as long as the characteristics of the flame retardant layer 150 are not impaired. , Stabilizer, carbon black, colorant and the like may be contained.

(Laminated structure of coating layer)
Next, the laminated structure 160 of the semi-conductive layer 130, the highly electrically insulating layer 140, and the flame-retardant layer 150 in the coating layer 120 will be further described.

The high electrical insulation layer 140 is thinner than the flame retardant layer 150. As a result, the combustibility 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 retardancy, while the laminated structure 160 is thinned to reduce the diameter of the insulated wire 100. Can be planned. As the highly electrically insulating layer 140, which is easily combusted, is made thinner, the flame-retardant layer 150 can be made thinner.

In order to make the high electrical insulating layer 140 thin while obtaining high insulating properties, the volume resistivity of the polymer composition (B) forming the high electrical insulating layer 140 is preferably 1 × 10 ¹⁶ Ωcm or more, more preferably. 1 x 10 ¹⁷ Ω cm 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 insulation layer 140 is more preferably 1/2 or less of the thickness of the flame retardant layer 150, and the thickness of the flame retardant layer 150. It is more preferably 1/3 or less of the diameter.

The semi-conductive layer 130 is arranged directly above the conductor 110 (in contact with the conductor 110), and functions as an unevenness relaxation layer that suppresses electric field concentration by covering the unevenness on the surface of the conductor 110. As a result, the highly electrically insulating layer 140 arranged on the semi-conductive layer 130 can be thinned. To increase the conductivity of the semiconductive layer 130, polymer composition for forming the semiconductive layer 130 volume resistivity of (A) is preferably not more than 1 × 10 ⁹ Ωcm. The lower limit of the volume resistivity of the polymer composition (A) is not particularly limited.

The semi-conductive layer 130 may cover the unevenness of the surface of the conductor 110 (the concave portion may be filled to smooth the surface), and the thickness of the semi-conductive layer 130 should be a desired thickness. Can be done. Here, the thickness of the semi-conductive layer 130 is expressed as the thickness on the convex portion (thinnest portion) of the twist on the surface of the conductor 110, that is, the thickness outside the outer diameter of the conductor 110.

If the semi-conductive layer 130 is too thick, it will hinder the diameter reduction and flame retardancy. Therefore, the thickness of the semi-conductive layer 130 is preferably thinner than the flame-retardant layer 150, more preferably 1/2 or less of the thickness of the flame-retardant layer 150, and the thickness of the flame-retardant layer 150. It is more preferably 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 highly electrically insulating layer 140, that is, the thickness of the semiconductive layer 130 and the thickness of the highly electrically insulating layer 140 The sum of the above is more preferably thinner than the thickness of the flame-retardant layer 150, and further 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, still 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.

As a result, the voltage applied to the flame retardant layer 150 can be kept relatively low. The flame-retardant layer 150 contains a large amount of additives such as a flame retardant, and its insulating property is more easily destroyed than that of the high-electrical insulating layer 140. By suppressing the voltage applied to the flame-retardant layer 150 to a low level, high insulation of the insulated wire 100 can be obtained.

In order to make the high electrical insulation layer 140 thin while sharing the voltage of 80% or more applied to the laminated portion of the high electrical insulation layer 140 and the flame retardant layer 150 to the high electrical insulation layer 140, the high electrical insulation layer 140 is provided. The volumetric resistance 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 sharing a voltage of 80% or more applied to the laminated portion of the high electrical insulation layer 140 and the flame retardant layer 150 to the high electrical insulation layer 140, the high electrical insulation layer is formed. The volume resistivity of the polymer composition (B) forming 140 is preferably 10 times or more, more preferably 50 times or more, more preferably more than the volume resistivity of the polymer composition (C) forming the flame retardant layer 150. Should be 100 times or more.

From the viewpoint of a small-diameter insulated wire, the outer diameter (diameter) of the insulated wire 100 is preferably 7 mm or less. The rated voltage (alternating current) of the insulated wire 100 is, for example, 3600 V or less. The small diameter also has the advantage that the semi-conductive layer 130, the highly electrically insulating layer 140, and the flame-retardant layer 150 can be easily crosslinked at the same time by irradiation crosslinking.

The upper limit of the thickness of the semi-conductive layer 130 (the thickness of the convex portion of the twist on the surface of the conductor 110, that is, the thinnest portion) is preferably 0.10 mm or less from the viewpoint of diameter reduction. .. The lower limit of the thickness of the semi-conductive layer 130 is not particularly limited as long as it can cover the unevenness of the surface of the conductor 110, but for example, the uniformity of the thickness of the semi-conductive layer 130 is improved to provide stable withstand voltage characteristics. From the viewpoint of obtaining, it is preferably 0.05 mm or more. The thickness of the portion of the twisted recess on the surface of the conductor 110 that fills the recess is preferably 1/2 or more of the outer diameter of the wire.

The upper limit of the thickness of the high electrical insulating layer 140 is preferably 0.15 mm or less, more preferably 0.10 mm or less, for example, from the viewpoint of reducing the diameter. The lower limit of the thickness of the high electric insulating layer 140 is not particularly limited as long as the desired insulating property can be obtained, but for example, the uniformity of the thickness of the high electric insulating layer 140 is enhanced to obtain stable insulating property. From the viewpoint of obtaining, it is preferably 0.05 mm or more.

The upper limit of the thickness of the flame-retardant layer 150 is preferably 0.30 mm or less, for example, from the viewpoint of reducing the diameter. The lower limit of the thickness of the flame-retardant layer 150 is not particularly limited as long as the thickness can obtain flame retardancy according to the thickness of the highly electrically insulating layer 140 (and the semi-conductive layer 130). From the viewpoint of increasing the uniformity of the thickness of the flame-retardant layer 150 and obtaining stable flame-retardant property, it is preferably 0.10 mm or more.

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

The semi-conductive layer 130, the highly electrically insulating layer 140, and the flame-retardant layer 150 are preferably formed on the outer periphery of the conductor 110 by simultaneous extrusion. As a result, dust in the atmosphere that causes electric field concentration adheres on the interface between the semiconductive layer 130 and the highly electrically insulating layer 140 and on the interface between the highly electrically insulating layer 140 and the flame retardant layer 150. Can be suppressed.

The semi-conductive layer 130 may be configured by a laminated structure of a plurality of semi-conductive layers (sub-semi-conductive layers), if necessary. Further, the high electrical insulating layer 140 may be composed of a laminated structure of a plurality of insulating layers (sub-insulating layers), if necessary. Further, the flame-retardant layer 150 may be composed of a laminated structure of a plurality of flame-retardant layers (sub-flame-retardant layers), if necessary.

As described above, according to the present embodiment, it is possible to obtain high insulation and high flame retardancy and reduce the diameter of the insulated wire.

The insulated wire according to the embodiment is not limited to the use of the insulated wire alone, and may be used in combination with other members as needed, such as being used for the core of a cable.

<Other Embodiments of the present invention>
Although one embodiment of the present invention has been described above in an exemplary and concrete manner, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the gist thereof. For example, other embodiments such as the following are also possible.

The insulated wire 100 according to another embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view perpendicular to the length direction showing an example of the structure of the insulated wire 100 according to another embodiment.

In another embodiment, the coating layer 120 arranged on the outer periphery of the conductor 110 is the semiconductive layer 130, the flame-retardant layer 150a arranged on the outer periphery of the semiconductive layer 130, and the outer periphery of the flame-retardant layer 150a. The highly electrically insulating layer 140 arranged above (arranged on the outer periphery of the semiconductive layer 130 via the flame retardant layer 150a) and the flame retardant layer 150b arranged on the outer periphery of the highly electrically insulating layer 140 It has a laminated structure 160 that is laminated. The flame-retardant layer 150a and the flame-retardant layer 150b constitute the entire flame-retardant layer 150.

That is, in another embodiment, the flame-retardant layer 150 is placed inside the high-electrical insulating layer 140 (conductor 110) in addition to the flame-retardant layer 150b arranged on the outside of the high-electrical insulating layer 140 (opposite to the conductor 110). It has a flame retardant layer 150a arranged on the side). Like the flame retardant layer 150b, the flame retardant layer 150a is formed from a polymer composition containing a flame retardant, and is formed, for example, by extruding the polymer composition onto the outer periphery of the semiconductive layer 130. If necessary, for example, in order to further enhance the flame retardancy, the flame retardant layer 150 having such a configuration may be used.

As described above, the flame retardant layer 150 may be arranged only on the outside of the high electric insulation layer 140, or may be arranged on both the outside and the inside of the high electric insulation layer 140. .. However, in order to enhance the flame retardancy of the insulated wire 100, it is preferable that the flame retardant layer 150 is arranged at least outside (on the outer circumference) of the high electrical insulating layer 140.

Next, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[Manufacturing of insulated wires]
As Examples 1 to 3 and Comparative Examples 1 to 3, an insulated wire having a laminated structure shown in FIG. 1 was produced as follows.

A polymer composition (A) for forming a semi-conductive layer, a polymer composition (B) for forming a highly electrically insulating layer, and a polymer composition (C) for forming a flame-retardant layer were prepared. The formulations of the polymer compositions (A) to (C) are shown in Tables 1 to 3, respectively.

As a conductor, a conductor having an outer diameter of 1.23 mm (37 twisted tin-plated copper strands having an outer diameter of 0.18 mm) was prepared. The polymer composition (A), the polymer composition (B), and the polymer composition (C) are simultaneously extruded on the outer periphery of the conductor and crosslinked by electron beam irradiation to form a semi-conductive layer and a highly electrically insulating layer. , And a flame-retardant layer was formed to produce an insulated electric wire.

In the insulated wires of Examples 1 to 3 and Comparative Examples 1 to 3, the thicknesses of the semi-conductive layer, the highly electrically insulating layer, and the flame-retardant layer were different. In Comparative Example 1, the semi-conductive layer was not formed. The thickness of each layer and the total coating thickness are shown in Table 4.

[Evaluation of insulated wires]
The insulating properties (electrical characteristics) and flame retardancy of the insulated wires of Examples 1 to 3 and Comparative Examples 1 to 3 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 DC stability test in which a direct current of 300 V was applied in a 3% NaCl aqueous solution at 85 ° C. according to EN50305.6.7. Those that did not short-circuit in 10 days, that is, those that took 240 hours or more to short-circuit were accepted (○), and those that short-circuited in less than 10 days, that is, those that took less than 240 hours to short-circuit were accepted. Those 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.

The VFT test was carried out according to the 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 the insulated wire was exposed to a flame for 60 seconds. Those that extinguished the fire within 60 seconds after removing the flame were evaluated as acceptable (○), and those that did not extinguish the fire within 60 seconds were evaluated as rejected (×).

The VTFT test was carried out according to the multi-row cable vertical combustion test (Blame propagation (bunched cables)) specified in EN50266-2-4. Specifically, seven insulated wires with a total length of 3.5 m were twisted into one bundle, 11 bundles were arranged vertically at equal intervals, burned for 20 minutes, self-extinguished, and then the carbonization length from the lower end was measured. .. If the carbonization length is 2.5 m or less, the result is acceptable (◯), and if the carbonization length exceeds 2.5 m, the result is rejected (x).

(Comprehensive evaluation)
For insulated wires that passed both the DC stability test and flame retardancy, the overall evaluation was passed (○), and for the others, the overall evaluation was rejected (×).

<Examples 1 to 3>
In Example 1, the thickness of the semi-conductive layer is 0.10 mm, the thickness of the highly electrically 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 semi-conductive layer is 0.05 mm, the thickness of the highly electrically 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 semi-conductive layer is 0.10 mm, the thickness of the highly electrically insulating layer is 0.08 mm, and the thickness of the flame-retardant layer is 0.29 mm.

In Examples 1 to 3, the thickness of the highly electrically insulating layer is thinner than the thickness of the flame-retardant layer, and the thickness of the semi-conductive layer is thinner than the thickness of the flame-retardant layer. Both sex and diameter reduction are compatible. Further, since the semi-conductive layer is formed, good insulating properties are obtained.

The thickness of the high electrical insulating layer is 1/2 or less of the thickness of the flame-retardant layer in Examples 1 to 3, and 1/3 or less of the thickness of the flame-retardant layer in Example 3. .. The thickness of the semi-conductive layer is ½ or less of the thickness of the flame-retardant layer in Examples 1 to 3, and 3/4 or less of the thickness of the flame-retardant layer in Example 2. The sum of the thickness of the semi-conductive layer and the thickness of the highly electrically 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. It is less than 2/3 of. In Example 3, the thickness of the highly electrically insulating layer is thinner than the thickness of the semiconductive layer.

<Comparative Examples 1 to 3>
In Comparative Example 1, the semi-conductive layer is not formed, the thickness of the highly electrically 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 semi-conductive layer is 0.10 mm, the thickness of the highly electrically 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 semi-conductive layer is 0.20 mm, the thickness of the highly electrically insulating layer is 0.10 mm, and the thickness of the flame-retardant layer is 0.20 mm.

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

In Comparative Example 2 and Comparative Example 3, the insulation property was passed because the semi-conductive layer was formed, but in Comparative Example 2, the thickness of the highly electrically insulating layer was equal to the thickness of the flame-retardant layer, and the comparison was made. In Example 3, the thickness of the semi-conductive layer is equal to the thickness of the flame-retardant layer, so that the flame retardancy is rejected.

The thickness of each layer is the same as in Example 1, and the polymer composition (A) forming the semi-conductive layer, the polymer composition (B) forming the highly electrically insulating layer, and the polymer forming the flame-retardant layer. Insulated electric wires of other examples having different formulations of the composition (C) are also produced, and the same characteristics as those of Examples 1 to 3 described above are obtained for these. For example, an insulated wire having a highly electrically insulating layer using a polymer composition (B) on the order of 10 ¹⁶ Ωcm in volume resistivity is produced, and the polymer composition (B) is 1 × 10 ¹⁶ Ωcm or more. Those having a volume resistivity of can be used. Also for example, to prepare a insulated wire volume resistivity with a semiconducting layer used 10 ⁸ [Omega] cm polymer composition of the order of the (A), as the polymer composition ^{(A), 1 × 10 9} Ωcm or less Those having a volume resistivity of can be used.

Although the present invention has been described above according to the embodiments, the present invention is not limited thereto. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

<Preferable Aspect of the Present Invention>
Hereinafter, preferred embodiments of the present invention will be added.

(Appendix 1)
With the conductor
A coating layer arranged on the outer circumference of the conductor and
Have,
The coating layer is
A semi-conductive layer arranged on the outer periphery of the conductor and formed of the polymer composition (A) containing a conductive agent and having a volume resistivity of 1 × 10 ⁹ Ωcm or less,
A highly electrically insulating layer formed of the polymer composition (B) arranged on the outer periphery of the semi-conductive layer and having a volume resistivity of 1 × 10 ¹⁶ Ωcm or more.
A flame retardant layer formed of the polymer composition (C) arranged at least on the outer periphery of the highly electrically insulating layer and containing a flame retardant, and
Have,
An insulated wire in which the thickness of the highly electrically insulating layer and the semiconductive layer are thinner than the thickness of the flame-retardant layer, respectively.

(Appendix 2)
The thickness of the highly electrically 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 semi-conductive 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 4)
The sum of the thickness of the semi-conductive layer and the thickness of the highly electrically insulating layer is preferably thinner than the thickness of the flame-retardant layer, and more preferably 2/3 or less of the thickness of the flame-retardant layer. The insulated wire according to any one of 3 to 3.

(Appendix 5)
The highly electrically insulating layer preferably has a voltage applied in the thickness direction of the laminated portion of the highly electrically insulating layer and the flame retardant layer of preferably 80% or more, more preferably 90% or more, still more preferably 95% or more. The insulated wire according to any one of Supplementary note 1 to 4, which shares the above.

(Appendix 6)
The insulated wire according to any one of Appendix 1 to 5, wherein the polymer composition (B) has a volume resistivity of 1 × 10 ¹⁷ Ωcm or more.

(Appendix 7)
The volume resistivity of the polymer composition (B) forming the highly electrically insulating layer is preferably 10 times or more, more preferably 10 times or more, the volume resistivity of the polymer composition (C) forming the flame-retardant layer. The insulated wire according to any one of Supplementary note 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 note 1 to 7, wherein the outer diameter of the insulated wire is 7 mm or less.

(Appendix 9)
The insulated wire according to any one of Supplementary note 1 to 8, wherein the thickness of the semi-conductive layer is 0.10 mm or less.

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

(Appendix 11)
The insulated wire according to any one of Appendix 1 to 10, wherein the flame-retardant layer has a thickness of 0.30 mm or less.

(Appendix 12)
The insulated wire according to any one of Supplementary note 1 to 11, wherein the semi-conductive layer is arranged directly above the conductor (in contact with the conductor).

(Appendix 13)
The insulated wire according to any one of Supplementary note 1 to 12, wherein the highly electrically insulating layer is arranged directly above the semi-conductive layer (in contact with the semi-conductive layer).

(Appendix 14)
The insulated wire according to any one of Supplementary note 1 to 13, wherein the flame-retardant layer is further arranged between the semi-conductive layer and the highly electrically insulating layer.

(Appendix 15)
The insulated wire according to any one of Supplementary note 1 to 14, wherein the flame-retardant layer is arranged directly above the high-electrical insulating layer (in contact with the high-electrical insulating layer).

(Appendix 16)
The insulated wire according to any one of Supplementary note 1 to 15, wherein the flame-retardant layer is the outermost layer of the insulated wire.

(Appendix 17)
The insulated wire according to any one of Supplementary note 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 Supplementary note 1 to 17, wherein the polymer composition (C) is an electrically 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 Coating layer 130 Semi-conductive layer 140 Highly electrical insulating layer 150, 150a, 150b Flame-retardant layer 160 Laminated structure

Claims (2)

With the conductor
A coating layer arranged on the outer circumference of the conductor and
Have,
The coating layer is
A semiconductive layer formed of a polymer composition (A) having a 1 × 10 ⁹ Ωcm or less of the volume resistivity comprise disposed conductive agent on the straight of the conductor,
Wherein a high electric insulating layer formed of a polymer composition having a straight is above the arrangement 1 × 10 ¹⁶ Ωcm or more volume resistivity of the semiconductive layer (B),
A flame retardant layer formed of the polymer composition (C) arranged at least on the outer periphery of the highly electrically insulating layer and containing a flame retardant, and
Have,
The thickness of the highly electrically insulating layer and the semi-conductive layer are thinner than the thickness of the flame-retardant layer, respectively.
The thickness of the semi-conductive layer is ½ or less of the thickness of the flame-retardant layer. Insulated electric wire for railway vehicles. The insulated wire for a railway vehicle according to claim 1, wherein the thickness of the highly electrically insulating layer is ½ or less of the thickness of the flame-retardant layer.

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