Multi-core cable

Abstract

The present disclosure provides a multi-core cable from which an outer sheath can be easily removed. A multi-core cable is provided with: a core part formed by twisting a plurality of electric wires; a release layer that covers the core part; and an outer skin covering the mold release layer, the tensile strength of the mold release layer being 10 MPa or more and 38 MPa or less, and the mold release layer being bonded to the outer skin.

Description

Technical Field

[0001] The present disclosure relates to a multi-core cable. Background Art

[0002] Patent Document 1 discloses a multi-core cable having: a core portion formed by twisting a plurality of core insulated wires; and a sheath layer covering the outer periphery of the core portion.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-109756

[0006] In order to connect the wires of a multi-core cable to a device, etc., the outer sheath covering the entire wires is conventionally removed by pulling the outer sheath along the length direction of the multi-core cable at the end of the multi-core cable. From the viewpoint of improving workability, it is required that the outer sheath of the multi-core cable can be easily removed. Summary of the invention

[0007] Therefore, an object of the present disclosure is to provide a multi-core cable whose outer sheath can be easily removed.

[0008] The multi-core cable disclosed herein comprises: a core formed by twisting a plurality of electric wires; a release layer covering the core; and a sheath covering the release layer, wherein the tensile strength of the release layer is 10 MPa to 38 MPa, and the release layer is bonded to the sheath.

[0009] Effects of the Invention

[0010] The present disclosure can provide a multi-core cable whose outer sheath can be easily removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a cross-sectional view of a multi-core cable according to one embodiment of the present disclosure, taken along a plane perpendicular to the longitudinal direction.

[0012] Figure 2 This is an explanatory diagram of a fiber having a core-sheath structure.

[0013] Figure 3 It is an explanatory diagram of the operation of removing the outer sheath at the end of the multi-core cable.

[0014] Description of Reference Numerals

[0015] 10: Multi-core cable

[0016] 10A: End

[0017] 11: Wires

[0018] 110: Core

[0019] 110A: Outer surface

[0020] 11A: Conductor

[0021] 11B: Insulator

[0022] 11C: Conductor wire

[0023] 111: First Wire

[0024] 111A: First conductor

[0025] 111B: First insulator

[0026] 111C: First conductor wire

[0027] 112: Second wire

[0028] 112A: Second conductor

[0029] 112B: Second insulator

[0030] 112C: Second conductor wire

[0031] 1120: twisted pair wire

[0032] 12: Release layer

[0033] 12A: Noodle

[0034] 13: Skin

[0035] 131: First Skin

[0036] 131A: Noodle

[0037] 132: Second skin

[0038] 14: Coating layer

[0039] 141: First coating layer

[0040] 142: Second coating layer

[0041] 20: Fiber

[0042] 21: Core

[0043] 22: Sheath

[0044] 31: Incision

[0045] 32: Hollow arrow

[0046] L13: Length. DETAILED DESCRIPTION

[0047] Hereinafter, specific implementation modes will be described.

[0048] [Description of Embodiments of the Present Disclosure]

[0049] First, the embodiments of the present disclosure will be described by way of example. In the following description, the same reference numerals are given to the same or corresponding elements, and the same description thereof will not be repeated.

[0050] (1) A multi-core cable according to one embodiment of the present disclosure includes: a core portion formed by twisting a plurality of electric wires; a release layer covering the core portion; and a sheath covering the release layer, wherein the tensile strength of the release layer is 10 MPa to 38 MPa, and the release layer is bonded to the sheath.

[0051] By setting the tensile strength of the release layer to 38 MPa or less, when the outer sheath to be removed is stretched in the longitudinal direction of the multi-core cable, the release layer can be easily cut, and the outer sheath can be easily removed.

[0052] By setting the tensile strength of the release layer to 10 MPa or more, it is possible to prevent the material such as the tape of the release layer from being cut during the production of the release layer, thereby improving the productivity of the multi-core cable.

[0053] Since the release layer is bonded to the outer skin, when removing the outer skin, the release layer and the outer skin can be peeled off from the core part as a whole, so that the outer skin can be easily removed.

[0054] (2) In the above (1), the difference between the melting temperature of the material contained in the surface of the release layer in contact with the outer skin and the melting temperature of the material contained in the surface of the outer skin in contact with the release layer may be 60° C. or less.

[0055] By setting the difference in melting temperature between the material contained in the surface of the release layer in contact with the outer skin and the material contained in the surface of the outer skin in contact with the release layer to less than 60°C, when the outer skin is extruded onto the release layer, the surface of the release layer in contact with the outer skin is melted, thereby making it easy to bond the release layer to the outer skin.

[0056] (3) In the above (1) or (2), the release layer may contain a plurality of materials, and the difference between the melting point of at least a portion of the material contained in the surface of the release layer in contact with the outer skin and the melting point of the material contained in the surface of the outer skin in contact with the release layer is 60°C or less.

[0057] By setting the difference between the melting temperature of at least a part of the material contained in the surface of the release layer in contact with the outer skin and the melting temperature of the material contained in the surface of the outer skin in contact with the release layer to 60°C or less, at least a part of the surface of the release layer in contact with the outer skin can be melted when the outer skin is extruded on the release layer. Therefore, when the outer skin is extruded, at least a part of the release layer can be bonded to the outer skin.

[0058] (4) In any one of the above (1) to (3), the release layer may include a nonwoven fabric.

[0059] By including the nonwoven fabric in the release layer, the release layer can be easily broken when removing the outer skin, thereby making it easy to remove the outer skin. In addition, by including the nonwoven fabric in the release layer, it is possible to prevent the generation of fine debris caused by tearing the release layer when removing the outer skin.

[0060] (5) In the above (4), the nonwoven fabric may include fibers having a core-sheath structure, wherein the core-sheath structure has a core and a sheath disposed outside the core.

[0061] The fibers contained in the nonwoven fabric have a core-sheath structure, and thus by selecting the materials of the core and the sheath, fibers that can meet the properties required of the fibers and the nonwoven fabric can be produced. For example, by using different materials for the core and the sheath, the properties of the fibers and the nonwoven fabric containing the fibers can be easily controlled.

[0062] [Details of the embodiments of the present disclosure]

[0063] Hereinafter, a specific example of a multi-core cable of an embodiment of the present disclosure (hereinafter, referred to as "this embodiment") is described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, but is shown by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0064] In this specification, the names of components may be described by adding "first", "second", etc., such as the first electric wire and the second electric wire. "First", "second", etc. are only recorded to distinguish the components and prevent confusion during description, and do not indicate the arrangement, priority, etc. Therefore, when there is no particular concern about confusion and the description is summarized, it can be recorded as "electric wire".

[0065] [Multi-core cable]

[0066] Figure 1 A schematic diagram of a cross section perpendicular to the length direction of the multi-core cable of this embodiment is shown in FIG. Figure 1 In the diagram, the length of the multi-core cable is along the Z axis, which is the axis perpendicular to the paper. Figure 1 , a cross section at an XY plane perpendicular to the Z axis is shown. Figure 1 This is a diagram schematically shown for the purpose of explanation, and the number and structure of the electric wires included in the multi-core cable of this embodiment are not limited to this form.

[0067] like Figure 1 As shown, the multi-core cable 10 of the present embodiment includes a core 110 formed by twisting a plurality of electric wires 11 , a release layer 12 covering the core 110 , and a sheath 13 covering the release layer 12 .

[0068] Each member included in the multi-core cable of this embodiment will be described.

[0069] (1) Core

[0070] The core 110 has a structure in which a plurality of electric wires 11 are twisted together.

[0071] (1-1) About electric wires

[0072] The electric wire 11 included in the core 110 may include a conductor 11A and an insulator 11B covering the conductor 11A.

[0073] (1-1-1) Conductor

[0074] The conductor 11A may be a stranded wire formed by twisting a plurality of conductor wires 11C.

[0075] For example, Figure 1 As shown, the first conductor 111A may be a stranded wire of a plurality of first conductor wires 111C. In addition, the second conductor 112A may also be a stranded wire of a plurality of second conductor wires 112C. Figure 1 In FIG. 1 , the first conductor wire 111C is shown as a circle, but the circle may be a twisted wire of a plurality of first conductor wires 111C or a single first conductor wire 111C. Figure 1 In FIG. 1 , regarding the second conductor wire 112C, a plurality of second conductor wires 112C are collectively shown by a single circle.

[0076] The material of the conductor 11A is not particularly limited, but, for example, a copper alloy or copper can be used. The conductor may or may not be plated.

[0077] (1-1-2) Insulator

[0078] like Figure 1 As shown, the insulator 11B may cover the outer surface of the conductor 11A.

[0079] (Resin material)

[0080] The insulator 11B may include a resin material. The resin material is not particularly limited, but for example, one or more resins selected from fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE), polyolefin resins such as polyethylene and polypropylene, and copolymers of olefins and comonomers (ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-methyl acrylate copolymer (EMA)) can be used. The resin of the insulator may be cross-linked or not.

[0081] (additive)

[0082] Insulator 11B may contain one or more additives selected from flame retardants, antioxidants, anti-degradation agents, acid absorbers, colorants, crosslinking agents, crosslinking aids, processing aids, fillers, lubricants, etc. in addition to the above-mentioned resin material.

[0083] (1-2) Regarding the structure of the electric wire in the core

[0084] The configuration of the plurality of electric wires 11 included in the core 110 of the multi-core cable 10 of this embodiment is not particularly limited. The plurality of electric wires 11 included in the core 110 may have any number or combination of electric wires 11 depending on the application of the multi-core cable 10 and the like.

[0085] For example, Figure 1 The illustrated multi-core cable 10 has a core 110 such that the core 110 may include two first electric wires 111 and two second electric wires 112 as the plurality of electric wires 11 .

[0086] The first electric wire 111 and the second electric wire 112 may have the same structure as the electric wire 11. Figure 1 As shown, the first electric wire 111 has a first conductor 111A as the conductor 11A and a first insulator 111B as the insulator 11B. The second electric wire 112 has a second conductor 112A as the conductor 11A and a second insulator 112B as the insulator 11B. The respective components are as described above.

[0087] The two second electric wires 112 may also be provided as a twisted pair of electric wires 1120 that are twisted in advance. Figure 1 In the case of the multi-core cable 10 , the twisted pair electric wires 1120 and the two first electric wires 111 are twisted together to form the core portion 110 .

[0088] By making the second electric wire 112 a twisted pair, degradation and attenuation of the transmitted signal can be suppressed. In addition, by making the second electric wire 112 a twisted pair, two wires can be handled together during wiring, thereby improving wiring workability.

[0089] The twisted pair electric wire 1120 may further include a coating layer 14 covering the two twisted second electric wires 112. The coating layer 14 may be composed of one layer, two layers of the first coating layer 141 and the second coating layer 142, or three or more layers.

[0090] The material of the coating layer 14 is not particularly limited, and for example, the same material as that of the insulator 11B may be used, or a material different from that of the insulator 11B may be used.

[0091] As the material of the first covering layer 141, for example, one or more selected from thermoplastic polyurethane elastomer, EVA, EEA, etc. can be used. As the material of the second covering layer 142, for example, thermoplastic polyurethane elastomer, etc. can be used.

[0092] The covering layer 14 may have a structure formed by winding a tape, or may be a resin tube formed by extrusion.

[0093] The twisted pair electric wire 1120 may have no coating layer 14 and may have a configuration in which the two second electric wires 112 are exposed.

[0094] (2) Release layer

[0095] The release layer 12 may be configured to cover the core 110 and directly contact the outer surface 110A of the core 110 .

[0096] The release layer 12 may have a structure such as a nonwoven fabric in a strip shape wound around the core 110. The strip may be, for example, spirally wound around the core 110. In this case, the angle of the spirally wound strip may be, for example, set to 25 degrees or more and 40 degrees or less, based on the central axis of the multi-core cable 10 along the longitudinal direction (0 degrees). The overlapping width of the strip may be, for example, set to 1 / 3 or more and 1 / 2 or less of the strip width.

[0097] The removal of the outer sheath 13 in the multi-core cable 10 can be performed, for example, by the following first step and second step. Figure 3 As shown, in the first process, a cut 31 reaching the release layer 12 can be made in the outer skin 13 at the end 10A of the multi-core cable 10. Then, in the second process, the outer skin 13 can be stretched and removed along the hollow arrow 32, that is, along the length direction of the multi-core cable 10.

[0098] In the first step, by selecting a length L13 corresponding to the distance from the end 10A of the multi-core cable 10 to the position where the cut 31 is made, the length L13 of the sheath 13 to be removed, that is, the length of the core 110 to be exposed can be selected.

[0099] Conventionally, for example, when the length L13 of the outer sheath 13 to be removed is 400 mm or more, the incision 31 is cut in the first step so that the length L13 of the outer sheath 13 to be removed each time is about 100 mm, and the first step and the second step are repeated, thereby removing the outer sheath 13 of the desired length. However, from the viewpoint of improving productivity, a multi-core cable 10 is required in which the outer sheath 13 can be completely removed by performing the first step and the second step once even if the length L13 of the outer sheath 13 to be removed is 400 mm or more. Therefore, in this specification, a multi-core cable from which the outer sheath can be easily removed refers to a multi-core cable from which the outer sheath 13 of the multi-core cable 10 having a length L13 of 400 mm along the longitudinal direction can be completely removed.

[0100] Therefore, the inventors of the present invention studied a multi-core cable 10 that can easily remove the outer sheath 13 along the length direction even if the length L13 of the outer sheath 13 to be removed is 400 mm or more. In the process of studying, the inventors of the present invention studied a configuration in which the release layer 12 is arranged between the core 110 and the outer sheath 13.

[0101] However, if the release layer 12 is disposed between the core 110 and the sheath 13, and the sheath 13 having a length L13 of 400 mm or more is to be removed at one time at the end 10A along the length direction of the multi-core cable 10, the release layer 12 may be stacked and blocked between the sheath 13 and the core 110. Furthermore, since the release layer 12 is blocked between the sheath 13 and the core 110, more force is required to pull the sheath 13, and removal of the sheath 13 may become difficult.

[0102] The inventors of the present invention studied the reason why the release layer 12 is blocked between the outer skin 13 and the core 110 when the outer skin 13 is removed. The results showed that the release layer 12 is not bonded to the outer skin 13 when the release layer 12 is blocked between the outer skin 13 and the core 110.

[0103] Therefore, in the multi-core cable 10 of the present embodiment, the release layer 12 can be bonded to the outer skin 13. Since the release layer 12 is bonded to the outer skin 13, when removing the outer skin 13, the release layer 12 and the outer skin 13 can be peeled off from the core 110 as a whole, so that the outer skin 13 can be easily removed. The adhesion of the release layer 12 to the outer skin 13 can be confirmed in any cross section perpendicular to the longitudinal direction of the multi-core cable 10, and when at least a part of the interface between the release layer 12 and the outer skin 13 is bonded, it can be determined that they are bonded.

[0104] The melting temperatures T12 and T13 of the material contained in surface 12A of release layer 12 in contact with outer skin 13 and surface 131A of outer skin 13 in contact with release layer 12 may be selected so that release layer 12 adheres to outer skin 13 .

[0105] Melting temperature T12 and melting temperature T13 may be the same, or T12<T13. Melting temperature T12 and melting temperature T13 may also be T12>T13. As long as the difference between melting temperature T12 and melting temperature T13 is about 60°C or less, the release layer 12 can be bonded to the outer skin 13.

[0106] Surface 12A of release layer 12 in contact with outer skin 13 and surface 131A of outer skin 13 in contact with release layer 12 have a certain thickness, and thus can be respectively referred to as a layer of release layer 12 in contact with outer skin 13 and a layer of outer skin 13 in contact with release layer 12 .

[0107] exist Figure 1 In the multi-core cable 10 shown, for example, the melting temperature of the release layer 12 is set as the melting temperature T12, and the melting temperature of the first outer sheath 131 is set as the melting temperature T13, and the melting temperatures can be compared.

[0108] The melting temperature refers to the peak temperature of the first endothermic peak that appears when the material to be evaluated is heated from room temperature (25° C.) at a heating rate of 10° C. / min by DSC (Differential Scanning Calorimetry).

[0109] The difference between the melting temperature T12 of the material contained in the surface 12A of the release layer 12 in contact with the outer skin 13 and the melting temperature T13 of the material contained in the surface 131A of the outer skin 13 in contact with the release layer 12 can be set to 60° C. or less.

[0110] By setting the difference between melting temperature T12 and melting temperature T13 to 60° C. or less, when the outer skin 13 is extruded on the release layer 12 , the release layer 12 is melted near the surface 12A in contact with the outer skin 13 , thereby making it easy to bond the release layer 12 to the outer skin 13 .

[0111] The difference between the melting temperature T12 and the melting temperature T13 may be 50° C. or less.

[0112] Therefore, the difference between the melting temperature T12 and the melting temperature T13 may be set to 0°C or higher and 60°C or lower, or may be set to 0°C or higher and 50°C or lower.

[0113] When release layer 12 includes a plurality of materials, the difference between melting temperature T121 of at least a portion of the material contained in surface 12A of release layer 12 in contact with outer skin 13 and melting temperature T13 of the material contained in surface 131A of outer skin 13 in contact with release layer 12 may be set to 60° C. or less.

[0114] By setting the difference between the melting temperature T121 and the melting temperature T13 to 60° C. or less, at least a portion of the surface 12A of the release layer 12 in contact with the outer skin 13 can be melted when the outer skin 13 is extruded onto the release layer 12. Therefore, when the outer skin 13 is extruded onto the release layer 12, at least a portion of the release layer 12 can be bonded to the outer skin 13.

[0115] The difference between the melting temperature T121 and the melting temperature T13 may be 50° C. or less.

[0116] Therefore, the difference between the melting temperature T121 and the melting temperature T13 may be set to 0°C or higher and 60°C or lower, or may be set to 0°C or higher and 50°C or lower.

[0117] The tensile strength of the release layer 12 can be set to 38 MPa or less. When the sheath 13 to be removed is stretched along the length direction of the multi-core cable 10, the release layer 12 can be easily cut and the sheath 13 can be easily removed.

[0118] The tensile strength of the release layer 12 may be 15 MPa or less. When the tensile strength of the release layer 12 is 15 MPa or less, the release layer 12 can be cut more easily, and the outer skin 13 can be removed more easily.

[0119] The tensile strength of the release layer 12 may be set to 10 MPa or more. By setting the tensile strength of the release layer 12 to 10 MPa or more, the tape of the release layer 12 is prevented from being cut during the production of the release layer 12, thereby improving the productivity of the multi-core cable.

[0120] Therefore, the tensile strength of the release layer 12 may be, for example, 10 MPa or more and 38 MPa or less.

[0121] The material of the release layer 12 is not particularly limited, and for example, the release layer 12 may include one or more resins selected from polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene and polypropylene, and the like.

[0122] The release layer 12 may be a nonwoven fabric of fibers containing a resin or the like, or a tape having a base material of a resin or the like.

[0123] As described above, the release layer 12 may include, for example, nonwoven fabric. When the release layer 12 includes nonwoven fabric, the release layer 12 can be easily torn when removing the outer skin 13, so that the outer skin 13 can be easily removed. In addition, when the release layer 12 includes nonwoven fabric, it is possible to prevent the generation of fine debris caused by tearing of the release layer 12 when removing the outer skin 13.

[0124] In the case where the release layer 12 comprises a nonwoven fabric, as Figure 2 As shown, the nonwoven fabric may include fibers 20 having a core-sheath structure, wherein the core-sheath structure includes a core 21 and a sheath 22 disposed outside the core 21. The core 21 and the sheath 22 may be made of the same material or different materials. Figure 2 This is a perspective view showing a portion of the fiber 20 having a core-sheath structure in a cross section viewed along a plane passing through the central axis.

[0125] The fibers contained in the nonwoven fabric have a core-sheath structure, and thus fibers that satisfy the properties required of the fibers and the nonwoven fabric can be produced by selecting the materials of the core 21 and the sheath 22. For example, by using different materials for the core 21 and the sheath 22, the properties of the fibers 20 and the nonwoven fabric containing the fibers 20 can be easily controlled.

[0126] For example, the fibers 20 can be formed to have a low melting temperature by using a material having a relatively high melting temperature such as polyethylene terephthalate for the core 21 and a material having a relatively low melting temperature such as polyethylene for the sheath 22. Therefore, the nonwoven fabric including the fibers 20 can also have a low melting temperature.

[0127] (3) Skin

[0128] The outer skin 13 may be configured to cover the release layer 12 and directly contact the release layer 12 .

[0129] Since the multi-core cable 10 has the outer sheath 13 , the electric wires 11 included in the core 110 are protected and the durability is improved.

[0130] (Resin material)

[0131] The outer skin 13 may include a resin material. The resin material is not particularly limited, but for example, polyolefin resins such as polyethylene and ethylene-vinyl acetate copolymer (EVA), polyurethane elastomers (polyurethane resins) such as thermoplastic polyurethane elastomer (TPU), polyester elastomers, or a composition formed by mixing at least two of them can be used.

[0132] like Figure 1 As shown, the outer skin 13 may also include a plurality of layers, such as a first outer skin 131 and a second outer skin 132, starting from a position close to the core 110. The outer skin 13 is not limited to Figure 1 The two-layer structure shown in the figure may be one layer or may include more than three layers. The first outer skin 131 and the second outer skin 132 may be made of different materials or the same material.

[0133] The materials of the first outer skin 131 and the second outer skin 132 are not particularly limited, and the resin materials described as the material of the outer skin 13 may be included.

[0134] The first outer skin 131 may contain, as a resin material, at least one selected from, for example, a polyurethane resin and a polyolefin-based resin.

[0135] The second sheath 132 may contain, for example, polyurethane resin having excellent wear resistance as a resin material. The second sheath 132 is configured to include the outer surface of the multi-core cable 10 , so the durability of the multi-core cable 10 can be improved by containing polyurethane resin as a resin material.

[0136] (additive)

[0137] In addition to the above-mentioned resin material, the outer skin 13 may contain one or more additives selected from flame retardants, antioxidants, anti-degradation agents, acid absorbers, colorants, crosslinking agents, crosslinking aids, processing aids, fillers, lubricants, and the like.

[0138] [Example]

[0139] Hereinafter, specific examples will be given for description, but the present invention is not limited to these examples.

[0140] (Evaluation method)

[0141] First, a method for evaluating electric wires produced in the following experimental examples will be described.

[0142] (1) Processability test

[0143] like Figure 3As shown, at the end 10A of the multi-core cable 10, a cut 31 reaching the release layer 12 is made at a position 408 mm away from the end 10A (first step). Next, as shown by the hollow arrow 32, the outer sheath 13 is stretched along the length direction of the multi-core cable 10 and the outer sheath 13 is removed (second step).

[0144] When the outer skin on the end side can be removed by the second step, the evaluation is A. When the outer skin on the end side cannot be removed by the second step, the evaluation is B.

[0145] (2) Melting temperature

[0146] The melting temperatures of the release layer 12 and the first outer skin 131 were evaluated by heating from room temperature (25° C.) at a heating rate of 10° C. / min using DSC. The peak temperature of the first endothermic peak in the obtained DSC curve was defined as the melting temperature.

[0147] (3) Tensile strength

[0148] The tensile strength of the nonwoven fabric used for the release layer 12 was measured using a tensile testing machine in accordance with JIS L 1913 (2010).

[0149] (Regarding the manufacturing conditions of multi-core cables)

[0150] Hereinafter, the multi-core cable in each experimental example will be described.

[0151] Experimental Examples 1 and 2 are embodiments, and Experimental Example 3 is a comparative example.

[0152] [Experimental Example 1, Experimental Example 2]

[0153] Make a cross section perpendicular to the length direction with Figure 1 The multi-core cable 10 shown is a multi-core cable of the same structure.

[0154] The column of composition in Table 1 shows the materials used for the release layer, the first outer skin, and the second outer skin.

[0155] The release layer 12 is formed by spirally winding a nonwoven fabric tape using fibers having a core-sheath structure in which the core is polyethylene terephthalate and the sheath covering the core is polyethylene around the core 110. In Experimental Example 2, the first outer skin and the second outer skin are the same, and the outer skin of the thermoplastic polyurethane elastomer has one layer.

[0156] The evaluation results of the tensile strength and melting temperature (T12, T121) of the release layer 12 and the melting temperature (T13) of the first outer skin 131 are also shown in the composition column of Table 1. The melting temperatures T12 and T121 of the release layer 12 are the melting temperatures of the polyethylene used for the sheath.

[0157] When the cross section of the obtained multi-core cable was observed, it was confirmed that the release layer 12 was adhered to the outer sheath 13 .

[0158] Table 1 shows the evaluation results.

[0159] [Experimental Example 3]

[0160] A multi-core cable was produced and evaluated under the same conditions as in Experimental Example 1 except that the materials of the release layer 12 and the first outer sheath 131 were changed.

[0161] [Table 1]

[0162]

Claims

1. A multi-core cable having: The core is made by twisting multiple wires together; a release layer covering the core; and An outer skin, covering the release layer, The tensile strength of the release layer is 10 MPa or more and 38 MPa or less. The release layer is bonded to the outer skin.

2. The multi-core cable according to claim 1, wherein: The difference between the melting temperature of the material contained in the surface of the release layer in contact with the outer skin and the melting temperature of the material contained in the surface of the outer skin in contact with the release layer is 60° C. or less.

3. The multi-core cable according to claim 1, wherein: The release layer comprises a variety of materials, The difference between the melting temperature of at least a part of the material contained in the surface of the release layer in contact with the outer skin and the melting temperature of the material contained in the surface of the outer skin in contact with the release layer is 60° C. or less.

4. The multi-core cable according to claim 1 or 2, wherein: The release layer comprises a nonwoven fabric.

5. The multi-core cable according to claim 4, wherein: The nonwoven fabric includes fibers having a core-sheath structure, wherein the core-sheath structure has a core and a sheath disposed outside the core.

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