Multi-core cable

Abstract

To provide a multi-core cable excellent in peeling properties of an outer peripheral coating layer even without arranging press winding between a plurality of coated wires and the outer peripheral coating layer.SOLUTION: A multi-core cable includes a plurality of coated wires having a powdery lubricant arranged on the surface and an outer peripheral coating layer covering the outer surfaces of the plurality of coated wires. The outer surfaces of the plurality of coated wires contact the peripheral coating layer through the powdery lubricant, and the coverage of the outer surfaces of the plurality of coated wires with the powdery lubricant is 15% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to multi-core cables. [Background technology]

[0002] Patent Document 1 discloses a coated wire characterized by having a coating resin around a plurality of electric wires or cables that are wrapped with electric wire / cable securing tape. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Utility Model Registration No. 3065274 Publication [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventionally, multi-core cables containing multiple insulated wires have been used. In multi-core cables, a tape-like material called a retaining wrap is spirally wound around the outer circumference of the multiple insulated wires, and the retaining wrap is placed between the multiple insulated wires and the outer coating layer (for example, Patent Document 1).

[0005] However, in multi-core cables where a retaining winding is placed between multiple insulated wires and the outer coating, moisture and other substances could penetrate the multi-core cable from the ends of the cable through the gap between the retaining winding and the insulated wires, or by traveling along the retaining winding. Therefore, it is conceivable to configure the cable so that the multiple insulated wires and the outer coating are in direct contact without a retaining winding. However, in this case, problems such as a decrease in the peeling characteristics when stripping the outer coating were encountered. For this reason, there was a need for a multi-core cable with excellent peeling characteristics of the outer coating even when a retaining winding is not placed between the multiple insulated wires and the outer coating.

[0006] Therefore, the present disclosure aims to provide a multi-core cable with excellent peeling characteristics of the outer coating layer, even when a retaining winding is not placed between the multiple coated wires and the outer coating layer. [Means for solving the problem]

[0007] The multi-core cable of this disclosure comprises multiple insulated wires on which a powdered lubricant is disposed on the surface, It has an outer covering layer that covers the outer surface of the plurality of insulated wires, The outer surfaces of the plurality of insulated wires and the outer coating layer are in contact with each other via the powdered lubricant. The coating rate of the outer surface of the multiple insulated wires by the aforementioned powdered lubricant is 15% or more. [Effects of the Invention]

[0008] According to this disclosure, even when a retaining winding is not placed between multiple insulated wires and the outer coating layer, a multi-core cable with excellent peeling characteristics of the outer coating layer can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional view perpendicular to the longitudinal direction of a multi-core cable according to one aspect of the present disclosure. [Figure 2] Figure 2 shows another example of a cross-sectional view perpendicular to the longitudinal direction of a multi-core cable according to one aspect of the present disclosure. [Figure 3] Figure 3 shows another example of a cross-sectional view perpendicular to the longitudinal direction of a multi-core cable according to one aspect of the present disclosure. [Figure 4] Figure 4 shows another example of a cross-sectional view perpendicular to the longitudinal direction of a multi-core cable according to one aspect of the present disclosure. [Figure 5A] Figure 5A is an explanatory diagram illustrating another example of the configuration of twisted-pair signal lines in a multi-core cable according to one aspect of the present disclosure. [Figure 5B] Figure 5B is an explanatory diagram illustrating another example of the configuration of twisted-pair signal lines in a multi-core cable according to one aspect of this disclosure. [Figure 6] Figure 6 is an explanatory diagram of the twist pitch. [Figure 7A] FIG. 7A is an explanatory diagram of a method for evaluating the coverage rate of the outer surfaces of a plurality of coated electric wires with a powdery lubricant. [Figure 7B] FIG. 7B is an explanatory diagram of a method for evaluating the coverage rate of the outer surfaces of a plurality of coated electric wires with a powdery lubricant. [Figure 8] FIG. 8 is an explanatory diagram of a method for evaluating adhesion in an experimental example. [Figure 9] FIG. 9 is an explanatory diagram of a flexure resistance test in an experimental example.

Embodiments for Carrying Out the Invention

[0010] The embodiments for carrying out the invention will be described below.

[0011] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0012] (1) A multi-core cable according to one aspect of the present disclosure includes a plurality of coated electric wires having a powdery lubricant disposed on their surfaces, an outer peripheral coating layer covering the outer surfaces of the plurality of coated electric wires, and the outer surfaces of the plurality of coated electric wires and the outer peripheral coating layer are in contact with each other via the powdery lubricant, and the coverage rate of the outer surfaces of the plurality of coated electric wires with the powdery lubricant is 15% or more.

[0013] By adopting a structure in which the outer surfaces of the plurality of coated electric wires and the outer peripheral coating layer are in contact with each other via a powdery lubricant, it is possible to suppress the intrusion of water into the multi-core cable as compared with the case where a constricting wrap is disposed on the outer surfaces of the plurality of coated electric wires.

[0014] By placing a powdered lubricant on the outer surface of multiple insulated wires and ensuring that the coating rate of the powdered lubricant on the outer surface of the multiple insulated wires is 15% or more, the outer coating layer can be easily peeled off from the multiple insulated wires. For example, the outer coating layer can be easily removed at the end of a multi-core cable using a wire stripper, resulting in a multi-core cable with excellent peelability and processability. Furthermore, by ensuring a coating rate of 15% or more, the force applied from the outer coating layer to the multiple insulated wires when the multi-core cable is bent can be suppressed, thereby improving its bending resistance.

[0015] (2) The coverage rate may be 25% or more and 70% or less.

[0016] By increasing the coverage rate to 25% or more, peelability, processability, and flexibility can be improved in particular.

[0017] By limiting the coverage to 70% or less, when a portion of the outer covering layer is removed at the end of a multi-core cable to connect it to equipment, the scattering of powdered lubricant into the surrounding area can be sufficiently suppressed.

[0018] (3) The plurality of insulated wires may include power lines and twisted signal wires.

[0019] Power lines can be used, for example, to supply power to connected equipment, and twisted signal lines can be used, for example, to transmit signals between devices. Since these functions are often required of multi-core cables, multiple insulated wires can be made into a multi-core cable that can be used for connecting various types of equipment by having both power lines and twisted signal lines.

[0020] (4) The plurality of insulated wires may include twisted wires.

[0021] By including twisted-pair wires in a multi-core cable, it can be made into a highly versatile multi-core cable that can be used for various applications.

[0022] (5) The powdered lubricant may contain talc.

[0023] The inclusion of talc in the powdered lubricant particularly enhances the peeling properties of the outer coating layer.

[0024] (6) The outer peripheral coating layer may have a first outer peripheral coating layer arranged on the side of the plurality of coated wires and a second outer peripheral coating layer that covers the outer surface of the first outer peripheral coating layer.

[0025] By constructing the outer covering layer from multiple layers, the properties such as the modulus of elasticity can be selected for each layer of the outer covering layer, making it easy to adjust and select properties such as the adhesion between multiple covered wires and the outer covering layer, and the bending resistance of multi-core cables.

[0026] [Details of the embodiments of this disclosure] A specific example of a multi-core cable according to one embodiment of this disclosure (hereinafter referred to as "this embodiment") will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to be shown in the claims, with all modifications within the meaning and scope of the claims being equivalent. (1) Examples of multi-core cable configurations First, an example of the configuration of the multi-core cable in this embodiment will be explained based on Figures 1 to 5B.

[0027] For the sake of brevity, the symbols for the lengths of each part of the power line 12, signal line 13, and twisted signal line 130 are shown in Figure 1, the symbols for the lengths of each part of the electric wire 21 and twisted electric wire 210 are shown in Figure 2, and the symbols for the lengths of each part of the power line 31 are shown in Figure 3.

[0028] As shown in Figures 1 to 4, the multi-core cable of this embodiment has a plurality of insulated wires 11 on which a powdered lubricant 15 is arranged on the surface, and an outer peripheral coating layer 16 that covers the outer surface of the plurality of insulated wires 11. In Figures 1 to 4, the Z-axis direction perpendicular to the plane of the paper corresponds to the longitudinal direction of the multi-core cables 10 to 40, the insulated wires 11, the cores 100 to 400, etc., and the XY plane formed by the X and Y axes is a plane perpendicular to the longitudinal direction of the multi-core cables 10 to 40, etc. <Figure 1 Configuration> Figure 1 shows a cross-sectional view of the multi-core cable 10 of this embodiment in a plane perpendicular to the longitudinal direction.

[0029] As shown in Figure 1, the multi-core cable 10 of this embodiment can have, for example, two power lines 12 and a twisted signal line 130 formed by twisting two signal lines 13 together, as insulated wires 11. That is, multiple insulated wires 11 can include, for example, power lines 12 and twisted signal lines 130.

[0030] The power line 12 can be used, for example, to supply power to connected equipment, and the twisted signal line 130 can be used, for example, to transmit signals between equipment. Since these functions are often required of multi-core cables, multiple insulated wires 11 can be made into a multi-core cable applicable to various equipment by having power lines 12 and twisted signal lines 130.

[0031] The insulated power wires 12 and twisted signal wires 130 of the multi-core cable 10 can be twisted together to form a core 100. When twisting together the insulated wires that make up the core 100, the direction of twisting is not particularly limited and they may be twisted in either a counterclockwise or clockwise direction. The same applies to the following cores 200 to 400.

[0032] The multiple insulated wires in the multi-core cable of this embodiment are not limited to the configuration example shown in Figure 1, and can have any number of insulated wires of any configuration depending on the equipment to which the multi-core cable is connected. Other configuration examples of the multiple insulated wires in the multi-core cable of this embodiment are described below. <Configuration of Figure 2> Figure 2 shows a cross-sectional view of a multi-core cable 20 in a plane perpendicular to the longitudinal direction, representing another configuration example of this embodiment.

[0033] For example, the multi-core cable 20 shown in Figure 2 has, as insulated wires 11, two power lines 12 and a paired signal wire 130 formed by twisting together two signal lines 13, as well as a paired wire 210 formed by twisting together two wires 21. In other words, in the multi-core cable 20, multiple insulated wires 11 include the paired wire 210. In the multi-core cable 20 shown in Figure 2, the core 200 includes the paired wire 210, and the power lines 12, the paired signal wires 130, and the paired wire 210 are twisted together.

[0034] By including twisted-pair wires 210 in the multi-core cable 20, a highly versatile multi-core cable can be made that can be used for various applications.

[0035] In the multi-core cables 10 and 20 shown in Figures 1 and 2, there is only one pair of twisted signal wires 130. However, the number of pairs of twisted signal wires 130 in a multi-core cable is not particularly limited and may be two or more.

[0036] For example, the twisted-pair electric wire 210 in Figure 2 can be replaced with a twisted-pair signal wire 130, resulting in a multi-core cable containing two sets of twisted-pair signal wires.

[0037] As described above, when there are two sets of twisted signal wires 130, it is preferable that one of the two power lines 12 is in contact with both sets of twisted signal wires 130, and the other of the two power lines 12 is in contact with both sets of twisted signal wires 130. Furthermore, it is preferable to provide an air gap between the two power lines 12 and the two sets of twisted signal wires 130 so that they do not come into contact with each other, in order to improve the bending resistance of the multicore cable. That is, in the multicore cable 20 shown in Figure 2, it is preferable to arrange each wire in the same way as when the twisted wires 210 are replaced with twisted signal wires 130.

[0038] In this specification, "flexibility" refers to the characteristic that the internal insulated wires are less likely to break even when a multi-core cable is repeatedly bent. <Configuration of Figure 3> Multi-core cables can also contain three or more power lines.

[0039] The multi-core cable 30 shown in Figure 3 has two power lines 12 and two additional power lines 31. When distinguishing between the two types of power lines in Figure 3, power line 12 is called the first power line and power line 31 is called the second power line.

[0040] When a multi-core cable contains three or more power lines, it may be composed only of power lines with the same outer diameter as the first conductor and the power lines, as described later. However, as shown in the multi-core cable 30 in Figure 3, it is also possible to use a combination of power lines with different outer diameters as the first conductor and the power lines.

[0041] Furthermore, the two second power lines do not need to be twisted together; they can be twisted together with other insulated wires to form a Core 300.

[0042] In the multi-core cable 30 shown in Figure 3, the core 300 includes multiple insulated wires 11, two first power lines 12, two second power lines 31, and a paired signal wire 130, with the power lines 12, power lines 31, and paired signal wire 130 being twisted together. <Configuration of Figure 4> As shown in the multi-core cable 40 in Figure 4, the electric wire 21 can also be a single wire instead of a twisted-pair electric wire 210. In the multi-core cable 40 shown in Figure 4, the core 400 contains the electric wire 21, and the two power lines 12, the twisted-pair signal lines 130, and the electric wire 21 are twisted together. <Other> The core twist pitch is not particularly limited, but it is preferably, for example, 10 to 25 times the outer diameter of the core.

[0043] This is because setting the core twist pitch to 10 times or more the core's outer diameter reduces surface irregularities, allowing the cross-section perpendicular to the longitudinal direction of the multi-core cable containing the core to approach a perfect circle. Furthermore, setting the core twist pitch to 25 times or less the core's outer diameter significantly enhances the flexibility of the multi-core cable containing the core, resulting in superior handling during wiring and other operations.

[0044] The outer diameter of the core refers to the diameter of the core in a cross-section perpendicular to the longitudinal direction of the multi-core cable. Therefore, the outer diameters of cores 100 to 400 shown in Figures 1 to 4 are outer diameter D100, outer diameter D200, outer diameter D300, and outer diameter D400. However, since the outer diameter of the core may vary slightly depending on the measurement cross-section, it is preferable to use the average value of the outer diameters measured in multiple cross-sections.

[0045] Therefore, the outer diameter of the core can be measured and calculated by the following procedure. At three measurement cross-sections arranged along the longitudinal direction of the multi-core cable, the length of the core's major axis is measured using a dimensional measuring instrument such as a micrometer. The distance between each measurement cross-section is set to 1m along the longitudinal direction of the multi-core cable. The average value of the length of the core's major axis measured at the three measurement cross-sections can then be used as the outer diameter of the core of the multi-core cable. The outer diameter of twisted signal wires and twisted electric wires, which are stranded wires made by twisting together multiple insulated wires, can be measured in the same manner.

[0046] The core twist pitch refers to the length over which the insulated wires constituting the core are twisted once. This length refers to the length along the central axis of the core. The core twist pitch can be measured in the same way as the twist pitch of the paired signal wires, which will be described later, so the explanation is omitted here. (2) Regarding each component of a multi-core cable Next, we will explain the individual components of a multi-core cable. (2-1) Power lines For example, as shown in Figure 1, the power line 12 has a first conductor 121 and a first insulating layer 122 covering the outer surface of the first conductor 121. Similarly, the power line 31 shown in Figure 3 also has a first conductor 311 and a first insulating layer 312 covering the outer surface of the first conductor 311.

[0047] Power lines 12 and 31 can be used, for example, to transmit power and control signals from an electronic control unit (ECU) to the outside of the vehicle. For example, power lines can be used to control an electric parking brake (EPB), which has a motor that drives the brake caliper. Power lines can also be used as power supply lines or control lines in a damper control system that modifies the hydraulic characteristics of the suspension.

[0048] The following explanation will use power line 12 as an example, but power line 31 can be configured in a similar manner. (First conductor) The first conductor 121 can be constructed by twisting together multiple strands of wire. The strands can be made of copper or a copper alloy. In addition to copper and copper alloys, the strands can also be made of materials with predetermined conductivity and flexibility, such as tin-plated soft copper wire or soft copper wire. The strands may also be made of hard copper wire. The cross-sectional area of ​​the first conductor 121 is not particularly limited, but for example, 1.0 mm². 2 3.0mm or more 2 The following is preferable. The first conductor 121 may also have multiple conductors 1211, which are made by twisting together multiple strands of wire, as shown in Figure 1. When the first conductor 121 has multiple conductors 1211, it is preferable that the sum of their cross-sectional areas satisfies the above range. Even in the case of the power line 31 shown in Figure 3, the first conductor 311 may also have multiple conductors 3111, which are made by twisting together multiple strands of wire.

[0049] The cross-sectional area of ​​the first conductor 121 is 3.0 mm². 2 By doing the following, the cross-sectional area of ​​the power line 12 can be reduced, and the cross-sectional area of ​​the multi-core cable 10 can also be reduced. As a result, the outer diameter of the multi-core cable 10 can be reduced, making it thinner.

[0050] Furthermore, the cross-sectional area of ​​the first conductor 121 is 1.0 mm². 2 By doing so, resistance when power is supplied can be suppressed. (First insulating layer) The first insulating layer 122 may contain a composition including a resin material, which is a synthetic resin, and can cover the first conductor 121 by being laminated on the outer circumference of the first conductor 121. The average thickness of the first insulating layer 122 is not particularly limited, but can be, for example, 0.1 mm or more and 0.5 mm or less. Here, "average thickness" refers to the average value of the thickness measured at any ten points. The same definition will be used below when referring to "average thickness" for other components, etc.

[0051] The main component resin of the first insulating layer 122, i.e., the resin present in the largest mass percentage, is not particularly limited as long as it has insulating properties, but from the viewpoint of improving flexibility at low temperatures, a copolymer of ethylene and an α-olefin having a carbonyl group is preferred. The content of the α-olefin having a carbonyl group in the main component resin is preferably 14% by mass or more, and more preferably 15% by mass or more. Furthermore, the content of the α-olefin having a carbonyl group is preferably 46% by mass or less, and more preferably 30% by mass or less. A content of α-olefin having a carbonyl group of 14% by mass or more is preferred because it can particularly improve flexibility at low temperatures. Furthermore, a content of α-olefin having a carbonyl group of 46% by mass or less is preferred because it can improve the mechanical properties such as the strength of the first insulating layer 122.

[0052] The α-olefin having a carbonyl group preferably contains one or more selected from the following: alkyl (meth)acrylates such as methyl (meth)acrylate and ethyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated acids such as (meth)acrylic acid, crotonic acid, maleic acid, and itaconic acid; vinyl ketones such as methyl vinyl ketone and phenyl vinyl ketone; and (meth)acrylamide. Among these, one or more selected from alkyl (meth)acrylates and vinyl esters are more preferred, and one or more selected from ethyl acrylate and vinyl acetate are even more preferred.

[0053] Examples of the main component resins mentioned above include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), and ethylene-butyl acrylate copolymer (EBA), with one or more selected from EVA and EEA being preferred among these.

[0054] The first insulating layer 122 may contain resins other than the main component resin described above.

[0055] The content of other resins in the resin material is preferably 60% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less. Furthermore, the first insulating layer 122 does not need to contain other resins.

[0056] The resin material contained in the first insulating layer 122 is not limited to the above example, and for example, the same resin material as in the case of the second insulating layer 132 described later can also be used.

[0057] The first insulating layer 122 may contain additives such as flame retardants, flame retardant aids, antioxidants, lubricants, colorants, reflective agents, opacifiers, processing stabilizers, and plasticizers.

[0058] Examples of the above-mentioned flame retardants include brominated flame retardants, halogenated flame retardants such as chlorine-based flame retardants, and non-halogenated flame retardants such as metal hydroxides, nitrogen-based flame retardants, and phosphorus-based flame retardants. Flame retardants can be used individually or in combination of two or more types.

[0059] Examples of brominated flame retardants include decabromodiphenylethane. Examples of chlorinated flame retardants include chlorinated paraffin, chlorinated polyethylene, chlorinated polyphenol, and perchlorpentacyclodecane. Examples of metal hydroxides include magnesium hydroxide and aluminum hydroxide. Examples of nitrogen-based flame retardants include melamine cyanurate, triazine, isocyanurate, urea, and guanidine. Examples of phosphorus-based flame retardants include metal phosphinates, phosphaphenanthrene, melamine phosphate, ammonium phosphate, phosphate esters, and polyphosphazene.

[0060] As for flame retardants, non-halogen-based flame retardants are preferred from the viewpoint of reducing environmental impact, and metal hydroxides, nitrogen-based flame retardants, and phosphorus-based flame retardants are more preferred.

[0061] When the first insulating layer 122 contains a flame retardant, the amount of flame retardant in the first insulating layer 122 is preferably 10 parts by mass or more, and more preferably 50 parts by mass or more, per 100 parts by mass of resin material. On the other hand, the amount of flame retardant is preferably 200 parts by mass or less, and more preferably 130 parts by mass or less, per 100 parts by mass of resin material. By setting the amount of flame retardant to 10 parts by mass or more per 100 parts by mass of resin material, a particularly sufficient flame retardant effect can be provided. Furthermore, by setting the amount of flame retardant to 200 parts by mass or less per 100 parts by mass of resin material, the extrusion molding of the first insulating layer 122 can be carried out particularly easily, and mechanical properties such as elongation and tensile strength can be improved.

[0062] The resin material of the first insulating layer 122 may or may not be crosslinked, but it is preferable that it be crosslinked. Methods for crosslinking the resin material of the first insulating layer 122 include irradiation with ionizing radiation, using a thermal crosslinking agent, and using a silane graftomer, with irradiation with ionizing radiation being preferred. Furthermore, to promote crosslinking, it is preferable to add a silane coupling agent to the composition forming the first insulating layer 122.

[0063] Furthermore, the first insulating layer 122 may be composed of multiple layers. (Outer diameter) The outer diameter D12 of the power line 12 is not particularly limited, but it is preferably 1.8 mm or more and 3.4 mm or less. By setting the outer diameter D12 of the power line 12 to 1.8 mm or more, the outer diameter D121 of the first conductor 121 and the thickness of the first insulating layer 122 can be sufficiently secured. This suppresses resistance when power is supplied and improves the durability of the power line. By setting the outer diameter D12 of the power line 12 to 3.4 mm or less, the power line 12 can be made thinner, and the multi-core cable can also be made thinner. This improves the handling when wiring multi-core cables, etc.

[0064] The outer diameter of the power line 12 can be measured in accordance with JIS C 3005 (2014). Specifically, the outer diameter of the power line can be measured at two or more points in the same plane perpendicular to the central axis (wire axis) of the power line, and the average value of these measurements can be taken as the outer diameter of the power line.

[0065] Furthermore, when measuring the outer diameter of a power line at two or more locations in the same plane perpendicular to the central axis of the power line, that is, within a single cross-section perpendicular to the central axis of the power line, the outer diameter will be measured along the diameter of the power line. When performing the above measurement, it is preferable to select the measurement locations such that the angles between the multiple diameters of the power line being measured are approximately equal. Specifically, for example, the outer diameter of the power line can be measured along two orthogonal diameters in a plane perpendicular to the central axis of the power line being measured, and the average value can be used as the outer diameter of the power line. The outer diameter of other insulated wires such as signal wires and electric wires, and the outer diameter of the conductors of each insulated wire can be measured in the same manner.

[0066] (2-2) Signal wires, twisted signal wires The signal wire 13 comprises a second conductor 131 and a second insulating layer 132 covering the outer surface of the second conductor 131. The outer diameter D131 of the second conductor 131 is preferably smaller than the outer diameter D121 of the first conductor 121. As described above, the signal wires 13 can be twisted together in pairs to form a paired signal wire 130. The two signal wires 13 twisted together along their longitudinal direction can be the same size and made of the same material.

[0067] (2-2-1) Signal Line The signal lines 13 can be used to transmit signals from sensors or to transmit control signals from the ECU. The two signal lines 13 can be used, for example, for wiring an anti-lock brake system (ABS). Each of the two signal lines 13 can be used, for example, to connect a differential wheel speed sensor to the vehicle's ECU. The two signal lines 13 may also be used to transmit other signals. (Second conductor) The second conductor 131 can be constructed by twisting together multiple strands of wire. The second conductor 131 may have one conductor made by twisting together multiple strands of wire, as shown in Figure 1, for example, or it may have multiple such conductors.

[0068] Specifically, for example, as shown in the signal line 13 in Figure 1, the second conductor 131 may be composed of a single conductor. Alternatively, as shown in the signal line 53 of the twisted-pair signal line 530A in Figure 5A, the second conductor 531 may have multiple conductors 5311. In the case of the signal line 53 shown in Figure 5A, it is preferable that the multiple conductors 5311 of the second conductor 531 are twisted together. The twisted-pair signal line 530A and signal line 53 shown in Figure 5A can be constructed in the same way as the other twisted-pair signal lines 130 and signal line 13, except that the configuration of the second conductor 531 is different. The twisted-pair signal line 530A may further have a second insulating layer 532 covering the second conductor 531, similar to the case of signal line 13.

[0069] The second conductor 131 may be made of the same material as the conductor constituting the first conductor 121 described above, or it may be made of a different material. The cross-sectional area of ​​the second conductor 131 is not particularly limited, but for example, 0.13 mm² 2 0.5mm or more 2 The following is possible. When the second conductor 531 has multiple conductors 5311, as shown in the signal line 53 in Figure 5A described above, it is preferable that the sum of the cross-sectional areas of the multiple conductors 5311 of the second conductor 531 satisfies the above range. (Second insulating layer) The material of the second insulating layer 132 is not particularly limited, but it may contain a resin material. As the resin material, 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), as well as polyester resins such as polyethylene terephthalate (PET), and polyolefin resins such as polyethylene and polypropylene, can be used.

[0070] The resin component of the second insulating layer 132 may or may not be crosslinked, but it is preferable that it be crosslinked. Methods for crosslinking the resin material of the second insulating layer 132 include irradiation with ionizing radiation, using a thermal crosslinking agent, and using a silane graftomer, with irradiation with ionizing radiation being preferred. In addition, to promote crosslinking, the composition forming the second insulating layer 132 may contain a silane coupling agent.

[0071] The second insulating layer 132 may further contain additives such as flame retardants, flame retardant enhancers, antioxidants, lubricants, colorants, reflective agents, opacifiers, processing stabilizers, and plasticizers. (Outer diameter) The outer diameter D13 of the signal wire 13 is not particularly limited, but it is preferably 1.00 mm or more and 2.20 mm or less. By setting the outer diameter D13 of the signal wire 13 to 1.00 mm or more, the bending rigidity of the signal wire 13 is particularly increased, improving workability when wiring the signal wire 13. By setting the outer diameter D13 of the signal wire 13 to 2.20 mm or less, the diameter of the signal wire 13 can be reduced, and the diameter of the multi-core cable can also be reduced. (2-2-2) Twisted-pair signal wires (Twist pitch of paired signal wires) The twist pitch of the twisted signal wire 130 is not particularly limited, but it is preferably 20 to 80 times the outer diameter D13 of the signal wire 13, and more preferably 25 to 70 times. By setting the twist pitch of the twisted signal wire 130 to 20 times or more the outer diameter D13 of the signal wire 13, the surface irregularities of the twisted signal wire can be reduced, making processing easier. Furthermore, by setting the twist pitch of the twisted signal wire 130 to 80 times or less the outer diameter D13 of the signal wire 13, the signal quality of the signal transmitted by the twisted signal wire can be improved.

[0072] The twist pitch of the twisted signal wire 130 refers to the length over which the signal wires 13 constituting the twisted signal wire 130 are twisted once. The length in question refers to the length along the central axis of the twisted signal wire 130.

[0073] Here, one signal wire 13 constituting the twisted signal wire 130 is designated as the first signal wire 13A, and the other signal wire as the second signal wire 13B. Figure 6 shows a side view of the twisted signal wire 130. On the side of the twisted signal wire 130, the first signal wire 13A and the second signal wire 13B appear in sequence repeatedly. As shown in Figure 6, on the side of the twisted signal wire 130, for the same cable, for example, the second signal wire 13B, the length along the central axis CA when it is twisted once becomes the twist pitch Pt of the twisted signal wire 130.

[0074] The twist pitch can be measured, for example, by the method described in JIS C 3002 (1992). Although the example given here is that of a 130 twisted signal wire, the twist pitch of the core has a similar meaning and can be evaluated in the same way as the twisted signal wire.

[0075] Furthermore, the outer diameter D130 of the twisted signal wire 130 can be approximately the same size as the outer diameter D12 of the power wire 12. (covering layer) The twisted signal wire may also have a covering layer 54 that covers the two twisted signal wires 13, as shown in the twisted signal wire 530B in Figure 5B. The covering layer 54 may consist of one layer, or it may consist of two layers, a first covering layer 541 and a second covering layer 542. As shown in Figure 5B, the first covering layer 541 can be arranged to cover the outer circumference of the two signal wires, and the second covering layer 542 can be arranged to cover the outer surface of the first covering layer 541.

[0076] The material of the coating layer 54 is not particularly limited; for example, the same material as the second insulating layer 132 may be used, or a different material may be used.

[0077] For the first coating layer 541, one or more materials selected from, for example, thermoplastic polyurethane elastomer, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), etc., can be suitably used. For the second coating layer 542, for example, thermoplastic polyurethane elastomer, etc., can be suitably used.

[0078] The coating layer 54 may be formed by wrapping tape around it, or it may be an extruded resin tube.

[0079] (2-3) Electric wires, twisted wires As shown in the multi-core cable 20 of Figure 2, the multi-core cable of this embodiment may also have a twisted pair wire 210 formed by twisting two wires 21 together. Furthermore, as shown in the multi-core cable 40 of Figure 4, the multi-core cable of this embodiment may also have a single wire 21.

[0080] The electric wire 21 may have a third conductor 211 and a third insulating layer 212 covering the outer surface of the third conductor 211. The outer diameter D211 of the third conductor 211 is preferably smaller than the outer diameter D121 of the first conductor 121 (see Figure 1). The electric wire 21 may have the same dimensions, such as outer diameter, and material as the signal wire 13.

[0081] (2-3-1) Electric wire The electric wire 21 can be used as a power supply line to electronic equipment to transmit signals from sensors, control signals from an ECU, etc. The electric wire 21 can also be used as a ground wire.

[0082] The third conductor 211 can be constructed by twisting together multiple strands of wire. The third conductor 211 may have one conductor made by twisting together multiple strands of wire, as shown in Figure 2, for example, or it may have multiple such conductors. When the third conductor 211 has multiple conductors, it is preferable that these multiple conductors are twisted together.

[0083] The third conductor 211 may be made of the same material as the conductors constituting the first conductor 121 and the second conductor 131, or it may be made of a different material. The cross-sectional area of ​​the third conductor 211 is not particularly limited, but for example, 0.13 mm². 2 0.5mm or more 2 The following is possible. Furthermore, if the third conductor 211 has multiple conductors, it is preferable that the sum of the cross-sectional areas of the multiple conductors in the third conductor 211 satisfies the above range.

[0084] (Third insulating layer) The material of the third insulating layer 212 is not particularly limited, but the third insulating layer 212 may contain, for example, a resin material similar to that described for the second insulating layer 132. Furthermore, the third insulating layer 212 may contain various additives as needed. Since suitably usable resin materials and the like have already been described for the second insulating layer 132, a further explanation is omitted here. (Outer diameter) The outer diameter D21 of the electric wire 21 is not particularly limited, but it is preferably 1.00 mm or more and 2.20 mm or less. By setting the outer diameter D21 of the electric wire 21 to 1.00 mm or more, the bending rigidity of the electric wire 21 is particularly increased, improving workability when wiring the electric wire 21. By setting the outer diameter D21 of the electric wire 21 to 2.20 mm or less, the electric wire 21 can be made thinner, and multi-core cables can also be made thinner.

[0085] (2-3-2) Stranded-pair wire (Twisting pitch of twisted wires) The twist pitch of the two wires 21 in the twisted wire pair 210 is not particularly limited, but it is preferably 20 to 70 times the outer diameter D21 of the wire 21, and more preferably 25 to 66 times. This is because setting the twist pitch of the twisted wire pair 210 to 20 times or more the outer diameter D21 of the wire 21 reduces surface irregularities of the twisted wire pair, making processing easier. Furthermore, setting the twist pitch of the twisted wire pair to 70 times or less the outer diameter D21 of the wire 21 improves the signal quality of the signal transmitted by the twisted wire pair. It also improves the flexibility of the twisted wire pair.

[0086] Furthermore, the outer diameter D210 of the twisted-pair wire 210 can be approximately the same size as the outer diameter D12 of the power line 12.

[0087] (2-4) Regarding the size of each part The size of the insulated wires in a multi-core cable can be selected according to the configuration and application of the multi-core cable, and is not particularly limited, but it is preferable that the following relationships be satisfied, for example.

[0088] In multi-core cables having power lines 12 and twisted signal lines 130, as shown in Figures 1 to 4, it is preferable that the following relationships are satisfied: The outer diameter D12 of the power line 12 is preferably approximately equal to the outer diameter D130 of the twisted signal line 130. Furthermore, it is preferable that the outer diameter D12 of the power line 12 is larger than the outer diameter D13 of the signal line 13.

[0089] When a multi-core cable 30, as shown in Figure 3, contains two types of power lines with different outer diameters, it is preferable that the following relationship is satisfied.

[0090] The outer diameter D31 of the second power line, power line 31, is preferably smaller than the outer diameter D12 of the first power line, power line 12. Furthermore, the outer diameter D31 of the second power line, power line 31, is preferably smaller than the outer diameter D130 of the twisted signal wire 130 and larger than the outer diameter D13 of the signal wire 13.

[0091] The outer diameter D311 of the first conductor 311 of the second power line, power line 31, is preferably smaller than the outer diameter D121 of the first conductor 121 of the first power line, power line 12. Furthermore, the outer diameter D311 of the first conductor 311 of the second power line, power line 31, is preferably larger than the outer diameter D131 of the second conductor 131 of the signal line 13.

[0092] When a multi-core cable 40, as shown in Figure 4, includes electric wires, it is preferable that the following relationship is satisfied: The outer diameter D21 of the electric wire 21 is preferably smaller than the outer diameter D12 of the power line 12. Also, the outer diameter D21 of the electric wire 21 may be the same as or different from the outer diameter D13 of the signal line 13.

[0093] The outer diameter D211 of the third conductor 211 of the electric wire 21 is preferably smaller than the outer diameter D121 of the first conductor 121 of the power line 12. Alternatively, the outer diameter D211 of the third conductor 211 may be the same as the outer diameter D131 of the second conductor 131.

[0094] (3) Outer coating layer The multi-core cable of this embodiment may have an outer covering layer 16 that covers the outer surface of the core. In this case, the outer covering layer 16 can be arranged to completely cover the core.

[0095] The material of the outer periphery coating layer 16 is not particularly limited, but can be made of, for example, a polyolefin resin such as polyethylene or ethylene-vinyl acetate copolymer (EVA), a polyurethane elastomer (polyurethane resin), a polyester elastomer, or a composition formed by mixing at least two of these.

[0096] For polyethylene, for example, "Solumer" (product name, manufactured by SK Global Chemical Co., LTD) is commercially available, and for EVA, for example, "Evaflex" (product name, manufactured by Mitsui DuPont Polychemical Co., Ltd.) is commercially available, and various grades of commercially available products can be selected and used as appropriate.

[0097] Furthermore, as the material for the outer periphery coating layer 16, for example, a crosslinked or non-crosslinked thermoplastic polyurethane (TPU) with excellent abrasion resistance can be used. Due to its excellent heat resistance, crosslinked thermoplastic polyurethane can be suitably used as the material for the outer periphery coating layer 16. Examples of thermoplastic polyurethanes that are commercially available include "Elastran" (trade name, manufactured by BASF) and "Milactran" (trade name, manufactured by Tosoh Corporation), and various grades of commercially available products can be appropriately selected and used.

[0098] The outer coating layer 16 may contain various additives as needed. These additives may include, for example, inorganic substances such as flame retardants. When inorganic substances such as flame retardants are incorporated into the resin material of the outer coating layer 16, the proportion of these additives is not particularly limited. For example, it is preferable to add 12 parts by mass or less of the inorganic substance such as a flame retardant per 100 parts by mass of the resin material, and more preferably 10 parts by mass or less.

[0099] Examples of inorganic substances to be added include one or more selected from antimony trioxide, aluminum hydroxide, magnesium hydroxide, and talc.

[0100] The outer periphery coating layer 16 may also have a first outer periphery coating layer 161 arranged on the side of the multiple insulated electric wires 11, and a second outer periphery coating layer 162 covering the outer surface of the first outer periphery coating layer 161. In this case, the first outer periphery coating layer 161 and the second outer periphery coating layer 162 may be made of different materials or the same material.

[0101] By composing the outer covering layer 16 from multiple layers, the properties such as the modulus of elasticity can be selected for each layer of the outer covering layer 16, making it easy to adjust and select properties such as the adhesion between multiple covered wires 11 and the outer covering layer, and the bending resistance of multi-core cables.

[0102] The materials for the first outer peripheral coating layer 161 and the second outer peripheral coating layer 162 are not particularly limited, and for example, the materials described above for the outer peripheral coating layer 16 can be used.

[0103] As the material for the first outer peripheral coating layer 161, one or more types selected from polyurethane resin and polyolefin resin can be suitably used.

[0104] A polyurethane resin with excellent abrasion resistance can be suitably used as the material for the second outer covering layer 162. Since the second outer covering layer 162 is located on the outside of the multi-core cable, using polyurethane resin as the material for the second outer covering layer 162 can particularly enhance the durability of the multi-core cable.

[0105] The first outer periphery coating layer 161 and the second outer periphery coating layer 162 may each contain the inorganic substances described above.

[0106] The material of the outer peripheral coating layer 16, for example, the material of the first outer peripheral coating layer 161, can fill at least a portion of the region A surrounded by multiple insulated electric wires 11, but the region A may also include portions that are not filled with the material of the outer peripheral coating layer 16 and are voids. (4) Powdered lubricant The multi-core cable 10 of this embodiment may have a powdered lubricant 15 on the surface of multiple insulated wires 11. The powdered lubricant 15 can be placed on the entire surface of the multiple insulated wires 11, but it may also be placed on the outer surface of the core 100, for example, and not on the inner surface of the core 100.

[0107] Furthermore, the outer surfaces of multiple insulated wires 11 and the outer coating layer 16 can come into contact via the powdered lubricant 15. In other words, a configuration can be achieved in which no retaining windings or the like are placed between the multiple insulated wires 11 and the outer coating layer 16. Therefore, in the parts where the multiple insulated wires 11 and the outer coating layer 16 come into contact via the powdered lubricant 15, the multiple insulated wires 11, the powdered lubricant 15, and the outer coating layer 16 are continuously stacked in that order. Note that the powdered lubricant 15 does not need to completely cover the outer surfaces of the multiple insulated wires 11. Therefore, a part of the outer surface of the multiple insulated wires 11 may be in direct contact with the outer coating layer 16.

[0108] By creating a structure in which the outer surfaces of multiple insulated wires 11 and the outer covering layer 16 are in contact via a powdered lubricant 15, water intrusion into the multi-core cable 10 can be suppressed compared to the case where a retaining winding is placed on the outer surfaces of multiple insulated wires 11.

[0109] The material of the powdered lubricant is not particularly limited, but the powdered lubricant 15 may include, for example, talc. The powdered lubricant 15 can also be composed of talc.

[0110] The inclusion of talc in the powdered lubricant 15 particularly enhances the peeling properties of the outer coating layer 16.

[0111] The coverage rate of the outer surface of the multiple insulated wires 11 by the powdered lubricant 15 is not particularly limited, but is preferably 15% or more, more preferably 25% or more, and even more preferably 30% or more.

[0112] By placing powdered lubricant 15 on the outer surface of multiple insulated wires 11 and ensuring that the coverage rate of the outer surface of the multiple insulated wires 11 by the powdered lubricant 15 is 15% or more, the outer coating layer 16 can be easily peeled off from the multiple insulated wires 11. For this reason, for example, the outer coating layer can be easily removed with a wire stripper at the end of a multi-core cable, resulting in a multi-core cable with excellent peeling characteristics and processability. Furthermore, by ensuring a coverage rate of 15% or more, the force applied from the outer coating layer to the multiple insulated wires when the multi-core cable is bent can be suppressed, thereby improving its bending resistance.

[0113] In this specification, peelability means that the outer coating layer can be easily peeled off from multiple insulated wires. Processability means that the ends of multi-core cables can be easily processed, for example, that the outer coating layer can be easily peeled off.

[0114] By setting the above coating ratio to 25% or more, peelability, processability, and flexibility can be improved in particular.

[0115] There is no particular upper limit to the coverage rate of the outer surfaces of multiple insulated wires 11 with the powdered lubricant 15, and the outer surfaces of multiple insulated wires 11 may be completely covered with the powdered lubricant 15, so it can be 100% or less.

[0116] However, if the coverage rate of the outer surface of multiple insulated wires 11 by the powdered lubricant 15 is too high, the powdered lubricant 15 may scatter into the surrounding area when a portion of the outer coating layer 16 is removed at the end of the multi-core cable 10 in order to connect the multi-core cable 10 to equipment, etc. For this reason, it is preferable that the coverage rate of the outer surface of multiple insulated wires 11 by the powdered lubricant 15 be 70% or less, and more preferably 60% or less. By setting the coverage rate of the outer surface of multiple insulated wires 11 to 70% or less, it is possible to sufficiently suppress the scattering of the powdered lubricant 15 into the surrounding area when a portion of the outer coating layer 16 is removed at the end of the multi-core cable 10 in order to connect the multi-core cable 10 to equipment, etc.

[0117] The coverage ratio of the outer surface of multiple insulated wires 11 by the above-mentioned powdered lubricant 15 can be calculated, for example, by the following procedure.

[0118] First, as shown in Figure 7A, the multi-core cable 70 to be evaluated can be divided into two parts along a plane passing through the central axis, that is, a plane containing the center O of the end face in the longitudinal direction. In the case of the multi-core cable 70 shown in Figure 7A, the multi-core cable 70 is divided into two parts along the straight line B, into a first member 70A and a second member 70B.

[0119] Figure 7B shows the divided surface of the first member 70A after the core 700 has been removed. The first member 70A, from which the core 700 has been removed, is composed of an outer peripheral coating layer 16, and powdered lubricant is attached to the area 71 where the core 700 was removed. The area ratio of the powdered lubricant within a measurement area 711 selected such that the width L711 of the area 71 where the core 700 was removed is equal to the length of the twist pitch of the core 700 can be calculated. The area ratio of the powdered lubricant within the measurement area 711 can be obtained, for example, by imaging the measurement area 711 with an imaging device such as a camera, binarizing the obtained image, calculating the area of ​​the area corresponding to the powdered lubricant, and dividing it by the area of ​​the measurement area 711.

[0120] It is preferable to perform the above evaluation on five or more samples of the multi-core cable to be evaluated, and to use the average value of the evaluation results of the evaluated samples as the coating rate of the outer surface of the multiple insulated wires 11 of the multi-core cable by the powdered lubricant 15. There is no particular upper limit to the number of samples to be evaluated, but it is preferable to keep it to 50 samples or less, taking into consideration the efficiency of the evaluation.

[0121] Although embodiments have been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. [Examples]

[0122] The present invention will be described with specific examples below, but it is not limited to these examples. (Evaluation method) First, we will explain the evaluation method for the multi-core cables fabricated in the following experimental example. (1) Length of each part (1-1) Outer diameter of conductor and insulated wire The outer diameters of conductors and insulated wires were measured in accordance with JIS C 3005 (2014). Specifically, the outer diameter was measured along two perpendicular diameters in a plane perpendicular to the central axis of the conductor or insulated wire, and the average value was taken as the outer diameter of the conductor or insulated wire. (1-2) Core outer diameter The outer diameter of the core was measured and calculated using the following procedure: The major axis length of the core was measured with a micrometer at three measurement cross-sections arranged along the longitudinal direction of the multi-core cable. The distance between each measurement cross-section was set to 1 m along the longitudinal direction of the multi-core cable. The average of the major axis lengths of the core measured at the three measurement cross-sections was then defined as the outer diameter of the core of the multi-core cable. (2) Coverage The coverage ratio of the outer surface of multiple insulated wires 11 by the powdered lubricant 15 was calculated using the following procedure.

[0123] First, as shown in Figure 7A, the multi-core cable 70 to be evaluated was divided into two parts along a plane passing through the central axis, that is, a plane containing the center O of the end face in the longitudinal direction. In the case of the multi-core cable 70 shown in Figure 7A, the multi-core cable 70 is divided into two parts along the straight line B, into a first member 70A and a second member 70B.

[0124] Figure 7B shows the divided surface of the first member 70A after the core 700 has been removed. The first member 70A, from which the core 700 has been removed, is composed of an outer peripheral coating layer 16, and powdered lubricant is attached to the area 71 where the core 700 was removed. The area ratio of the powdered lubricant within a measurement area 711 selected such that the width L711 of the area 71 where the core 700 was removed is equal to the length of the twist pitch of the core 700 can be calculated. The area ratio of the powdered lubricant within the measurement area 711 was obtained by imaging the measurement area 711 with an imaging device, binarizing the obtained image, calculating the area of ​​the area corresponding to the powdered lubricant, and dividing it by the area of ​​the measurement area 711.

[0125] For the same multi-core cable in the experimental example, the above evaluation was performed on 10 samples, and the average of the evaluation results from the 10 samples was taken as the coating rate of the outer surface of the multiple insulated wires 11 with the powdered lubricant 15 in the multi-core cable in the experimental example. The evaluation results are shown in the "Coating Rate" column of Table 1. (3) Adhesion Test The adhesion strength was evaluated in accordance with JASO D 625-2. Specifically, the adhesion strength was measured using a measuring jig 81 provided with through holes that only allow the core 800, which consists of multiple insulated wires as shown in Figure 8, to pass through. The above adhesion strength refers to the adhesion strength between the core and the outer coating layer.

[0126] First, the outer sheathing layer 16 of the multi-core cable 80 to be evaluated was removed, except for a portion, to expose the core 800. At this time, as shown in Figure 8, the outer sheathing layer 16 was left in such a way that the length L80 of the remaining portion along the longitudinal direction of the multi-core cable 80 was 50 mm.

[0127] Then, the exposed core 800 was inserted into the through-hole of the measuring jig 81. As a result, the multi-core cable 80 is set in the measuring jig 81, as shown in Figure 8.

[0128] Next, with the measuring jig 81 fixed, the multi-core cable 80 was pulled at a speed of 250 mm / min along arrow C in Figure 8. Then, the outer covering layer 16 peeled off from the core 800, and the magnitude of the force applied when the core 800 passed through the through hole of the measuring jig 81 and moved downwards from the measuring jig 81 was measured. The magnitude of the measured force represents the adhesion force per 50 mm length of the outer covering layer 16.

[0129] For the same experimental example of a multi-core cable, the above evaluation was performed on 10 samples, and the average value of the adhesion force of the 10 samples was taken as the adhesion force of the multi-core cable.

[0130] When the adhesion force is 100N or less, the outer coating layer can be easily peeled off from multiple coated wires, meaning it is a multi-core cable with excellent peeling characteristics. (4) Processability (4-1) Rating 1 In each experimental example, when attempting to strip 50 mm of the outer coating layer from the end of a multi-core cable using a wire stripper with a constant force, a score of 0 was given if the outer coating layer could not be stripped, and 1 was given if it could be stripped.

[0131] Then, for the multi-core cable in the same experimental example, the above evaluation was performed on 10 samples, and the evaluation was given as A if the sum of the evaluation results of the 10 samples was 7 points or more and 10 points or less, B if it was 3 points or more and 6 points or less, and C if it was 2 points or less.

[0132] If the evaluation result for Evaluation 1 is A, it means that the outer coating layer can be easily peeled off from multiple coated wires, i.e., it is a multi-core cable with excellent peeling characteristics and processability, with peeling characteristics decreasing in the order of B and C. (4-2) Rating 2 At the end of each multi-core cable prepared in the experiment, the outer coating layer was stripped by 50 mm using a wire stripper. If the insulating layer of the insulated wires constituting the core stretched longitudinally, resulting in a misalignment of 1 mm or more between the conductor tip and the insulating layer tip, a score of 0 was given. A score of 0 was also given if the outer coating layer could not be stripped. A score of 1 was given if no such misalignment occurred in any of the insulated wires constituting the core, or if the misalignment was less than 1 mm.

[0133] Then, for the multi-core cable in the same experimental example, the above evaluation was performed on 10 samples, and the evaluation was given as A if the sum of the evaluation results of the 10 samples was 7 points or more and 10 points or less, B if it was 3 points or more and 6 points or less, and C if it was 2 points or less.

[0134] If the evaluation result for Evaluation 2 is A, it means that the multi-core cable can be attached to equipment and other devices without any problems after the outer sheathing layer has been removed, and the likelihood of defects increases in the order of B and C. (4-3) Rating 3 At the end of each multi-core cable prepared in the experimental example, the outer coating layer was stripped by 50 mm using a wire stripper. If the total weight of the powdered lubricant scattered around, the outer coating layer, and the powdered lubricant adhering to the core and removed by tapping each component with a fingertip was 0.01 g or more, a score of 0 was given. If the total weight of the powdered lubricant was less than 0.01 g, a score of 1 was given. In this evaluation, if the outer coating layer could not be stripped, it was to be cut and removed using a razor or similar tool.

[0135] Then, for the multi-core cable in the same experimental example, the above evaluation was performed on 10 samples, and the evaluation was given as A if the sum of the evaluation results of the 10 samples was 7 points or more and 10 points or less, B if it was 3 points or more and 6 points or less, and C if it was 2 points or less.

[0136] If the evaluation result for Evaluation 3 is A, it means that when the outer coating layer is peeled off, almost no powdery lubricant is scattered into the surrounding area, indicating that it is a multi-core cable with excellent processability. Processability decreases in the order of B and C. (5) Flexural resistance test The multi-core cables obtained in the following experimental examples were subjected to bending resistance tests using a method conforming to JIS C 6851 (2006) (Test Method for Optical Fiber Characteristics).

[0137] Specifically, as shown in Figure 9, the multi-core cable 90 to be evaluated was placed vertically between two 60mm diameter first mandrels 911 and second mandrel 912, which were arranged horizontally and parallel to each other. The upper end of the multi-core cable 90 was then bent horizontally by 90° so that it abutted against the upper side of the first mandrel 911, and then bent horizontally by 90° so that it abutted against the upper side of the second mandrel 912. This process was repeated in a -30°C constant temperature bath. This repetition was performed while measuring the resistance values ​​of all two power lines 12 and two signal lines 13 in the multi-core cable 10 shown in Figure 1, which was prepared in the following experimental example. The number of bends until the resistance increased to more than 10 times the initial resistance value was used as the index value for the bending resistance test. In the above bending resistance test, one bend was defined as bending the multi-core cable 90 to the right in Figure 9, then bending it to the left, and then bending it back to the right.

[0138] The index value of the flexural resistance test, i.e., the number of flexions, indicates superior flexural resistance.

[0139] A rating was given for 6 million or more flexion cycles, a rating of B for 4 million to less than 6 million flexion cycles, and a rating of C for less than 4 million flexion cycles.

[0140] It means that when the evaluation of the flexure resistance test is A, it is the most excellent in flexure resistance, and the evaluation decreases in the order of B and C. (6) Evaluation Regarding the evaluation 1 to evaluation 3 of the workability and the flexure resistance, when the evaluation is A for each, 2 points are given, when the evaluation is B, 1 point is given, and when the evaluation is C, 0 point is given.

[0141] Then, when the total of the evaluation points for the evaluation 1 to evaluation 3 of the workability and the flexure resistance is 8 points, the evaluation is A, when it is 5 points or more and 7 points or less, the evaluation is B, and when it is 4 points or less, the evaluation is C.

[0142] When the above evaluation is A, it means that it is the most excellent in the peeling property, workability, and flexure resistance, and the properties decrease in the order of B and C. When the evaluation is A or B, it can be said that it is a multi-core cable having practically sufficient performance in terms of the peeling property, workability, and flexure resistance. (Experimental Example) Hereinafter, the experimental conditions will be described. Experimental Examples 3 to Experimental Example 9 are examples, and Experimental Examples 1 and Experimental Example 2 are comparative examples. [Experimental Example 1] The multi-core cable 10 shown in FIG. 1 was manufactured and evaluated. The manufactured multi-core cable 10 has, as the covered electric wire 11, two power lines 12 and a twisted signal line 130 including two signal lines 13. The power line 12 and the twisted signal line 130 are twisted together to form the core 100.

[0143] The power line 12 includes a first conductor 121 formed by twisting seven conductor 1211. The conductor 1211 is formed by twisting 50 copper alloy wires, the outer diameter D121 of the first conductor 121 is 2.0 mm, and the cross-sectional area is 1.8 mm 2 It was. Crosslinked polyethylene was used for the first insulating layer 122. The outer diameter D12 of the power line 12 was 2.6 mm.

[0144] The twisted signal line 130 is formed by twisting two signal lines 13 including a second conductor 131. The second conductor 131 is formed by twisting 40 copper alloy wires, the outer diameter D131 of the second conductor 131 is 0.58 mm, and the cross-sectional area is 0.2 mm 2The second insulating layer 132 was made of cross-linked polyethylene. The outer diameter D13 of the signal wire 13 was 1.4 mm.

[0145] The core 100 is formed by twisting the two power lines 12 and the twisted signal line 130 together along their longitudinal direction. The outer diameter D100 of the core was 5.8 mm. A powdered lubricant 15, which is talc, was applied to the outer surface of the core 100. As a result, the powdered lubricant 15 is present on the surfaces of multiple insulated wires 11.

[0146] Then, an outer covering layer 16 was arranged to cover the outer surface of the core 100, which consists of multiple insulated wires 11. The outer surface of the multiple insulated wires 11 and the outer covering layer 16 are in contact via a powdered lubricant 15.

[0147] The outer periphery coating layer 16 was formed by a first outer periphery coating layer 161 made of cross-linked polyethylene and a second outer periphery coating layer 162 made of cross-linked polyurethane, which was arranged to cover the outer surface of the first outer periphery coating layer 161. The outer diameter of the outer periphery coating layer 16 was 8.0 mm.

[0148] The multi-core cables obtained were evaluated as described above. The evaluation results are shown in Table 1. [Experimental Examples 2-9] A multi-core cable was fabricated and evaluated in the same manner as in Experimental Example 1, except that the amount of powdered lubricant applied to the outer surface of multiple insulated wires 11 was changed.

[0149] The evaluation results are shown in Table 1.

[0150] [Table 1] As shown in Table 1, there is a correlation between the coating rate of the outer surface of multiple insulated wires 11 with the powdered lubricant 15 and the adhesion force. It was confirmed that the adhesion force can be significantly reduced to 100N or less by setting the coating rate to 15% or more. In other words, it was confirmed that a multi-core cable with excellent peeling characteristics of the outer coating layer can be made even when a retaining winding is not placed between the multiple insulated wires and the outer coating layer.

[0151] Furthermore, it was confirmed that by setting the coating ratio to 15% or more, processability and bending resistance also improved, resulting in an evaluation of A or B. This is thought to be because setting the coating ratio to 15% or more makes it easier to peel the outer coating layer from the multiple insulated wires, and also suppresses the force applied from the outer coating layer to the multiple insulated wires when the multi-core cable is bent.

[0152] Furthermore, by increasing the coverage rate to 25% or more, peeling characteristics and bending resistance can be further improved. By increasing the coverage rate to 70% or less, when removing a portion of the outer covering layer at the end of a multi-core cable to connect it to equipment, the scattering of powdered lubricant into the surrounding area can be sufficiently suppressed. [Explanation of Symbols]

[0153] 10, 20, 30, 40, 70, 80, 90 multi-core cables 100, 200, 300, 400, 700, 800 cores D100, D200, D300, D400 Core outer diameter 11 Insulated wires 12 Power lines (Power line 1) D12 Outer diameter of power line 121 First Conductor D121 Outer diameter of the first conductor 1211 Conductor 122 First insulating layer 13 signal lines D13 Outer diameter of signal wire 130 twisted pair signal wires D130 Outer diameter of twisted signal wire 131 Second Conductor D131 Outer diameter of the second conductor 132 Second insulating layer 13A First signal line 13B Second signal line CA center axis Pt twist pitch 15. Powdered lubricant 16 Outer coating layer 161 First outer coating layer 162 Second outer coating layer 21 Electric wire D21 Outer diameter of electric wire 210 stranded wire 211 Third conductor D211 Outer diameter of the third conductor 212 Third insulating layer 31 Power lines (Second power line) D31 Outer diameter of power line 311 First conductor D311 Outer diameter of the first conductor 3111 Conductor 312 First insulating layer Area A 53 Signal Line 531 Second conductor 5311 Conductor 532 Second insulating layer 530A twisted pair signal wire 530B twisted pair signal wire 54 Covering layer 541 1st coating layer 542 Second coating layer 70A First component 70B Second component 71 areas 711 Measurement area O center B straight line 81 Measuring fixture C arrow 911 First Mandrel 912 Second Mandrel

Claims

1. Multiple insulated wires with a powdered lubricant on their surface, It has an outer covering layer that covers the outer surface of the plurality of insulated wires, The aforementioned plurality of insulated wires include power lines and twisted signal wires, The power line and the twisted signal line are twisted together to form a core. The outer surfaces of the plurality of insulated wires and the outer coating layer are in contact with each other via the powdered lubricant. The coating rate of the outer surface of the plurality of insulated wires by the aforementioned powdered lubricant is 25% or more and 70% or less. A multi-core cable in which the powdered lubricant is disposed on the outer surface of the core and not on the inner surface of the core.

2. The multi-core cable according to claim 1, wherein the plurality of insulated wires include twisted-pair wires.

3. The multi-core cable according to claim 1 or claim 2, wherein the powdered lubricant contains talc.

4. The multi-core cable according to any one of claims 1 to 3, wherein the outer covering layer comprises a first outer covering layer arranged on the side of the plurality of covered electric wires and a second outer covering layer covering the outer surface of the first outer covering layer.

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