Communication cable

Abstract

Communication cable (1), comprising: a conductor (2); an insulating coating (3) covering the outer circumference of the conductor (2); and a magnetic coating layer (8) covering the outside of the insulating coating (3), wherein the magnetic cladding layer (8) contains a magnetic material, and the magnetic material has a particle shape with an average particle diameter of not more than 50 µm and an aspect ratio of at least 1.5 and not more than 4, wherein the average particle diameter is the D50 value of the equivalent circular diameter when observed by electron microscopy, and the magnetic cladding layer (8) contains no magnetic additive with an aspect ratio greater than 4 apart from unavoidable impurities.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a communication cable. TECHNICAL BACKGROUND

[0002] In communication cables used in automobiles and the like, there are cases where a shielding layer is provided on the outer surface of a core wire to suppress the penetration of noise from outside and the radiation of noise to the outside. An example of such a shielding layer is a shielding layer covering the outer periphery of a core wire using a material in which a powdered magnetic material is dispersed in a high polymer material.

[0003] For example, Patent Document 1 discloses a magnetic shielding cable provided with a magnetic shielding layer formed by a layer of magnetic powder sandwiched between coating film layers. As a specific configuration of the cable, a form of cable is disclosed that includes a central conductor, an insulating layer covering the periphery of the central conductor, an electromagnetic shielding layer covering the periphery of the insulating layer, an inner coating layer covering the periphery of the electromagnetic shielding layer, a magnetic shielding layer covering the periphery of the inner coating layer, and an outer coating layer covering the periphery of the magnetic shielding layer. The magnetic shielding layer is formed by a layer of magnetic powder sandwiched between coating film layers.The magnetic shielding layer is designed as a braided shielding layer or a side-wound shielding layer with stranded copper or copper alloy wires. When using a communication cable in a high-frequency band of 1 GHz or more, as in the above form, there are many cases where a shielding body made of a metal material, such as a metal braid, is provided, and a shielding layer containing a powdered magnetic material is provided outside it.

[0004] DE 698 14 500 T2 discloses a shielding layer for shielding magnetism and radio waves and for absorbing radio waves, as well as a method for producing the same.

[0005] US Pat. No. 6,765,144 B1 discloses an arrangement for shielding an implanted medical device from the effects of radiofrequency radiation and for emitting magnetic resonance signals during magnetic resonance imaging. The arrangement comprises an implanted medical device and a magnetic shield made of nanomagnetic material arranged between the medical device and the radiofrequency radiation.

[0006] JP 2006 - 93 416 A discloses an electromagnetic wave noise suppression film comprising a base substance containing a binder and electromagnetic wave absorbing particles having an aspect ratio of 5 or less, and a composite layer which is an integrated body of a part of the binder and a magnetic substance. PREVIOUSLY KNOWN TECHNICAL DOCUMENTSPATENT DOCUMENTS Patent document 1: JP 2016 - 197 509 A Patent document 2: JP 2016 - 201 272 A Patent document 3: JP H11 - 86 641 A Patent document 4: JP 2004 - 311 600 A OVERVIEW OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In communication cables, there are many cases where part of a coating layer of the outer peripheral portion is removed, for example, to connect an end portion to an external member such as a terminal. In such cases, when a shielding layer made of a material obtained by mixing a powdered magnetic material with a polymer material is provided as the coating layer, when the shielding layer is removed, the particles of the magnetic material form a powdery substance (scaling) with the high polymer material, which tends to exfoliate and disperse. If such a scale is generated and adheres to the constituent parts, such as a conductor, of the communication cable or an external member to be connected, the electrical connection and the physical connection between the communication cable and the external member may be impaired.In particular, when the communication cable has a shielding body formed of a metal braid and a coating layer containing a magnetic material provided on the outer periphery thereof, debris originating from the coating layer is likely to be kept in a state where it clogs the mesh of the braid structure of the shielding body and is likely to seriously impair the connection between the communication cable and the external member.

[0008] In view of the above, an object of the present invention is to provide a communication cable provided with a coating layer containing a powdery magnetic material and capable of suppressing the occurrence of a powdery substance containing a magnetic material in the processing of the coating layer. MEANS FOR SOLVING THE TASK

[0009] A communication cable according to the present disclosure is a communication cable including a conductor, an insulating coating covering the outer periphery of the conductor, and a magnetic coating layer covering the outside of the insulating coating, and the magnetic coating layer includes a magnetic material having a particulate shape with an average particle diameter of not more than 50 μm and an aspect ratio of not more than 4. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0010] The communication cable according to the present disclosure is a communication cable provided with a coating layer containing a powdery magnetic material and capable of suppressing the occurrence of a powdery substance containing a magnetic material during processing of the coating layer. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a cross-sectional view showing a configuration of a communication cable according to an embodiment of the present disclosure. Fig. 2 is a side view showing an end portion of the communication cable. EMBODIMENTS OF THE INVENTION

[0011] First, an embodiment of the present disclosure will be described.

[0012] A communication cable according to the present disclosure is a communication cable including a conductor, an insulating coating covering the outer periphery of the conductor, and a magnetic coating layer covering the outside of the insulating coating, and the magnetic coating layer includes a magnetic material having a particulate shape with an average particle diameter of not more than 50 μm and an aspect ratio of not more than 4.

[0013] The communication cable includes a magnetic sheath layer containing a magnetic material on the outer periphery of the core wire, in which the insulating coating is provided on the outer periphery of the conductor. By absorbing electromagnetic waves that cause noise, the magnetic sheath layer exhibits noise-shielding properties, and the penetration of noise from outside and the emission of noise to the outside can be suppressed. Since the magnetic material contained in the magnetic sheath layer has a particle shape with an average particle diameter of no more than 50 μm and an aspect ratio of no more than 4, the occurrence of a powdery substance containing a magnetic material can be suppressed when the magnetic sheath layer is processed, e.g.by removing the magnetic coating layer at the end portion of the communication cable. As a result, it is unlikely that a situation will occur in which the generated powdery substance disperses or flakes off and adheres to the components of the communication cable, such as a conductor, or to an external element, thereby impairing the electrical connection and the physical connection between the communication cable and the external element.

[0014] Preferably, the aspect ratio of the magnetic material is not greater than 2. This can particularly effectively suppress the occurrence of the powdery substance during the processing of the magnetic cladding layer.

[0015] Preferably, the magnetic material in the magnetic cladding layer is dispersed in a polymer material, containing at least 350 parts by mass and at most 750 parts by mass of the magnetic material per 100 parts by mass of the polymer material. Accordingly, the occurrence of the powdery substance from the magnetic cladding layer can be effectively suppressed while simultaneously sufficiently maintaining the noise shielding effect of the magnetic cladding layer.

[0016] Preferably, a braid layer in the form of a braided body made of metal strands is interposed between the insulating coating and the magnetic sheath layer. Accordingly, the noise shielding performance of the communication cable can be further improved by the braid layer. Since the braid layer is located within the magnetic sheath layer, if the powdery substance occurs during processing of the magnetic sheath layer, it will clog the mesh of the braided body, making it difficult to remove the powdery substance. Since the particle diameter and aspect ratio of the magnetic material contained in the magnetic sheath layer are limited to a predetermined upper limit or less, the occurrence of the powdery substance is suppressed, so that even in the presence of a braid layer, such a situation is unlikely to occur.

[0017] In this case, it is preferable that the communication cable includes an exposed braid portion in which the magnetic sheath layer has been removed and the braid layer is exposed. Such an exposed braid portion can be formed by removing the layer provided outside the braid layer, including the magnetic sheath layer, at the terminal or the like of the communication cable, and can be used for connection to an external member such as a terminal. When removing the magnetic sheath layer, processing such as cutting the magnetic sheath layer is required.Since the possibility of the powdery substance leaking out of the magnetic cladding layer, resulting in dispersion and peeling of the powdery substance at the time of processing, is suppressed, it is unlikely that a situation will occur where the powdery substance clogs the mesh of the braid layer and impairs the connection with the external element using the exposed part of the braid.

[0018] In this case, it is preferable that the communication cable further includes an exposed conductor portion in which the magnetic sheath layer, braid layer, and insulating coating are all removed, leaving the conductor exposed. Since the appearance of the powdery substance from the magnetic sheath layer is suppressed, the powdery substance is unlikely to adhere to the surface of the conductor and interfere with the connection when connecting the exposed portion of the conductor to an external element such as a terminal.

[0019] Preferably, the communication cable further includes an outer sheath layer covering an outer periphery of the magnetic sheath layer and containing no magnetic material. Accordingly, the magnetic sheath layer can be physically protected by the outer sheath layer, making it easy to maintain a high noise shielding effect by the magnetic sheath layer. Furthermore, by providing the outer sheath layer, dispersion and detachment of the powdery substance from the magnetic sheath layer during processing of the magnetic sheath layer can be effectively suppressed.

[0020] In this case, it is preferable that the magnetic cladding layer and the outer cladding layer each contain polymer materials that are compatible with each other. Accordingly, the outer cladding layer can further enhance the effect of suppressing dispersion and detachment of the powdery substance from the magnetic cladding layer.

[0021] Hereinafter, a communication cable according to an embodiment of the present disclosure will be described in detail. Overall structure of the communication cable

[0022] Fig. 1 shows a cross-sectional view of a communication cable 1 according to an embodiment of the present disclosure along a line perpendicular to the axial direction. Fig. 2 a side view of the structure of an end section of the communication cable 1.

[0023] The communication cable 1 is designed as a coaxial cable. Specifically, the communication cable 1 is provided with a core wire 4 having a conductor 2 and an insulating coating 3 covering the outer periphery of the conductor 2. A metal foil 5 and a braided layer 6 formed as a braided body or braided body of metal strands are provided as a metallic shielding layer 7 on the outer periphery of the core wire 4. The metal foil 5 covers the outer periphery of the core wire 4, and the braided layer 6 covers the outer periphery of the metal foil 5. A magnetic sheath layer 8 containing a magnetic material is provided on the outer periphery of the metallic shielding layer 7. Furthermore, an outer sheath layer 9 containing no magnetic material is provided on the outer periphery of the magnetic sheath layer 8.As will be described in detail later, in the communication cable 1 according to the present embodiment, the particle diameter and the aspect ratio of the magnetic material contained in the magnetic coating layer 8 are limited to a predetermined upper limit or less.

[0024] Preferably, an exposed portion 10 comprising an exposed braid portion 11 and an exposed conductor portion 12 is provided at at least one of the two ends of the communication cable 1. At the exposed braid portion 11, the outer sheath layer 9 and the magnetic sheath layer 8 have been removed, and the braid layer 6 is exposed. The exposed conductor portion 12 is located on the front end side of the communication cable 1 and is adjacent to the exposed braid portion 11. In the exposed conductor portion 12, the braid layer 6, the metal foil 5 and the insulating coating 3 of the core wire 4, as well as the outer sheath layer 9 and the magnetic sheath layer 8 are removed, and the conductor 2 constituting the core wire 4 is exposed. Since the exposed portion 10 is formed at the end of the communication cable 1, the communication cable 1 can be electrically connected to an external element, such asa terminal. The braid layer 6 exposed at the exposed braid portion 11 can be connected to an outer conductor terminal, and the conductor 2 exposed at the exposed conductor portion 12 can be connected, for example, to an inner conductor terminal. The exposed braid portion 11 can be formed, for example, by cutting the entire circumference of the outer covering layer 9 and the magnetic covering layer 8 at a portion near the end of the communication cable 1 and removing it by pulling out a portion on the front end side of the communication cable 1 relative to the cutting position. By removing a portion on the front end side of the exposed braid layer 6 and further removing the metal foil 5 and the insulating coating 3 at the same location, the exposed conductor portion 12 can be formed.Accordingly, the exposed portion 10 in which the conductor 2 and the braid layer 6 are adjacent to each other and exposed in a step-like manner is formed at the end portion of the communication cable 1.

[0025] The above-described communication cable 1, which is configured as a coaxial cable in which the metallic shielding layer 7 and the magnetic covering layer 8 are provided on the outer periphery of the core wire 4, can be suitably used for transmitting high-frequency signals of 1 GHz or higher. However, the communication cable according to the present disclosure is not limited to the above configuration as long as the magnetic covering layer 8 covers the outer periphery of the core wire 4, and any configuration can be adopted depending on the communication frequency or usage. The magnetic covering layer 8 can cover the outer periphery of the core wire 4 directly or via another layer such as the metallic shielding layer 7.

[0026] Although a single insulated wire is used as the core wire 4 as an example in the above aspect, multiple insulated wires may also be used. Specifically, a core wire may be configured such that a pair of insulated wires are twisted together or wired in parallel to transmit different or differential signals. If the influence of noise is not so significant, only the metal foil 5 or the braid layer 6 may be arranged as the metallic shield layer 7, or the metallic shield layer 7 may be omitted. As the metallic shield layer 7, a shape other than the metal foil 5 and the braid layer 6, for example, a horizontally wound wire, may also be used. If the need for the function of protecting the magnetic cladding layer 8 or the like is not so great, the outer cladding layer 9 may also be omitted.Although the described layers are each in direct contact with the outer peripheries of the inner layers of the components in the above form, the communication cable 1 may also include other layers as components than those described above. The components of the coaxial cable-type communication cable 1 shown above are described in detail below. core wire

[0027] The core wire 4 of the communication cable 1 transmits electrical signals and includes a conductor 2 and an insulating coating 3 covering the outer periphery of the conductor 2. The materials from which the conductor 2 and the insulating coating 3 are formed are not particularly limited.

[0028] Although various metallic materials can be used as the material for the conductor 2, a copper alloy is preferable due to its high conductivity. Although the conductor 2 may be formed as a single wire, it is preferable for the conductor 2 to be a twisted wire formed by twisting multiple strands (e.g., seven) together in order to improve flexibility during bending. In this case, after the strands are twisted together, they may also be compressed and formed into a compressed and twisted wire. When the conductor 2 is formed as a twisted wire, the twisted wire may be composed of a single type or two or more types of strands.

[0029] The insulating coating 3 preferably contains an insulating polymer material as the main component. Examples of the polymer material are polyolefins such as polyethylene and polypropylene, halogen-based polymers such as polyvinyl chloride, engineering plastics such as polystyrene, polytetrafluoroethylene, and polyphenylene sulfide, as well as various elastomers and rubber. In order to improve communication properties, it is preferable to use a polymer material with low molecular polarity. In particular, it is preferable to use a non-polar polymer material such as a polyolefin, e.g., polypropylene. As the polymer material, only a single type of polymer material may be used, or two or more types of polymer materials may be used in combination by mixing, layering, or the like. The polymer material may be crosslinked or foamed. The insulating coating 3 may optionally contain, in addition to the polymer material, an additive such as, for example,a flame retardant. However, it is preferable that the insulating coating 3 does not contain an additive of a magnetic material, such as that contained in the magnetic cladding layer 8.

[0030] The diameter of the conductor 2 and the thickness of the insulating coating 3 are not subject to any particular restrictions. The conductor cross-sectional area is, for example, in the range of 0.05 mm 2 up to 1.0 mm 2 . Furthermore, the thickness of the insulating coating 3 can be, for example, between 0.1 mm and 0.5 mm. Metallic shielding layer

[0031] The metallic shielding layer 7 is provided between the core wire 4 and the magnetic cladding layer 8 and has a two-layer structure in which the metal foil 5 and the braid layer 6 are layered.

[0032] The metal foil 5 is formed as a thin film of a metallic material. The type of metal from which the metal foil 5 is formed is not particularly limited, and examples include copper, a copper alloy, aluminum, and an aluminum alloy. The metal foil 5 may be formed of a single metal or of two or more metals superimposed on one another. The metal foil 5 may also be formed by a metal layer bonded to the base material, e.g., a polymer film, by vapor deposition, coating, adhesion, or the like, or by an independent thin metal film. To improve noise shielding, it is preferable that the metal foil 5 be arranged perpendicular to the core wire 4.

[0033] The braid layer 6 is formed as a braided body composed of a plurality of metal strands alternately intertwined to form a hollow cylindrical shape. Examples of metal strands constituting the braid layer 6 include metal materials such as copper, a copper alloy, aluminum, and an aluminum alloy, or those in which the surface of these metal materials is coated with tin or the like.

[0034] The metallic shielding layer 7 constitutes an outer conductor in the coaxial cable structure and plays a role in shielding the noise penetrating the core wire 4 and the noise emanating from the core wire 4 through electrostatic shielding. As will be described later, the magnetic sheath layer 8 in the communication cable 1 also has a noise shielding effect. However, when the communication cable 1 is used for high-frequency communication of 1 GHz or more, the influence of noise tends to be very large. For this reason, the metallic shielding layer 7, together with the magnetic sheath layer 8, can effectively suppress the influence of noise. Since the metallic foil 5 and the braid layer 6 are used together as the metallic shielding layer 7, the noise shielding effect can be improved.The order in which the metal foil 5 and the braid layer 6 are layered is not particularly limited, but it is preferable to arrange the metal foil 5 on the inside and the braid layer 6 on the outside, for example, for the reason of reducing signal loss. Magnetic coating layer

[0035] The magnetic cladding layer 8 covers the outer periphery of the core wire 4. In the present embodiment, the magnetic cladding layer 8 covers the outer periphery of the core wire 4 with the metallic shielding layer 7 interposed therebetween.

[0036] The magnetic sheath layer 8 contains a particulate magnetic material. The magnetic material contained in the magnetic sheath layer 8 is preferably a ferromagnetic material, and more preferably a metal or a metal compound having soft magnetic properties. Since a magnetic material, particularly a soft magnetic material, is contained in the magnetic sheath layer 8, excellent noise shielding of the communication cable 1 can be achieved. In other words, it is possible to suppress a phenomenon in which noise from the outside of the communication cable 1 penetrates into the communication cable 1 and affects the signals transmitted in the core wire 4, and a phenomenon in which noise caused by the signals transmitted in the core wire 4 is radiated to the outside of the communication cable 1.This is because the high-frequency electromagnetic waves that can cause noise are absorbed and attenuated due to magnetic loss in the magnetic material of the magnetic cladding layer 8.

[0037] Examples of soft magnetic materials that exhibit high noise shielding properties in the high frequency range of 1 GHz or higher include iron (pure iron or iron with a small amount of carbon), silicon steel, Fe-Si-Al alloy (Sendust), magnetic stainless steel such as Fe-Cr-Al-Si alloy and Fe-Cr-Si alloy, Fe-Ni-based alloy (Permalloy), and ferrite. Among these, the use of an Fe-Si-Al alloy or ferrite is particularly preferable due to their particularly good shielding properties. The ferrite can be Ni-Zn-based ferrite, Mn-Zn-based ferrite, or the like. Only one type of magnetic material can be used, or two or more types of magnetic materials can be blended or mixed together, as appropriate.

[0038] In the magnetic cladding layer 8, the magnetic material has a particulate form and is dispersed in the matrix material. A non-magnetic dielectric is preferably used as the matrix material. From the viewpoint of ensuring flexibility and the like, it is preferable to use a polymer material such as a plastic material as the matrix material. Similar to the polymer material that forms the insulating coating 3 of the core wire 4, examples of the polymer material include polyolefins such as polyethylene and polypropylene, halogen-based polymers such as polyvinyl chloride, engineering plastics such as polystyrene, polytetrafluoroethylene, polyphenylene sulfide, various elastomers, and rubbers. Among these, polyolefins such as polypropylene or polyvinyl chloride are preferably used, which are excellent in, for example, insulation and heat resistance. It may be used if necessary.A single type of polymer material or two or more types of polymer materials blended by mixing or layering may be used. The polymer material may be cross-linked or foamed. The polymer material forming the magnetic cladding layer 8 may be identical to or different from the polymer material from which the insulating coating 3 of the core wire 4 is formed.

[0039] The magnetic cladding layer 8 may contain an additive, such as a flame retardant, in addition to the polymer material. The magnetic cladding layer 8 contains no magnetic additive with an aspect ratio greater than 4, except for unavoidable impurities. It is also preferable that the magnetic cladding layer 8 contains no non-magnetic additives with a particle diameter and aspect ratio greater than the upper limit described later with respect to magnetic materials, except for unavoidable impurities.

[0040] The average particle diameter (D50 value of the equivalent circular diameter when observed by electron microscopy) of the particles of the magnetic material contained in the magnetic cladding layer 8 is not more than 50 μm. If the particle diameter of the magnetic material is too large, a situation may easily occur in which the fabric of the composite material in which the magnetic material is dispersed in the matrix material becomes brittle, and the magnetic material and the matrix material form a powdery substance (deposits) and separate from the magnetic cladding layer 8. However, since the average particle diameter of the magnetic material is limited to not more than 50 μm, the affinity between the magnetic material and the matrix material is improved, and the bond between the magnetic material and the matrix material is strengthened.Accordingly, when the magnetic cladding layer 8 is subjected to processing such as cutting, the magnetic material and the matrix material are unlikely to form deposits, and the deposits formed are unlikely to detach from the magnetic cladding layer 8 and disperse or exfoliate. The magnetic material having an average particle diameter of not more than 50 μm also exhibits excellent noise shielding performance. In order to achieve a higher noise shielding effect and suppress the occurrence of deposits, the particle diameter of the magnetic material is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.Although it is preferable that the magnetic material is dispersed in the matrix material without secondary particles being formed by aggregation or the like, in the case of secondary particles being formed, it is preferable that the secondary particle diameter is not larger than the upper limit described above, just like the primary particle diameter.

[0041] The particle diameter of the magnetic material has no specific lower limit. However, to avoid saturating the scale suppression effect of fine particles or to ensure the handling of the magnetic material, the average particle diameter is preferably set to at least 0.5 µm. Preferably, the average particle diameter is set to at least 1 µm or at least 5 µm.

[0042] Furthermore, the aspect ratio of the magnetic material particles contained in the magnetic cladding layer 8 is not greater than 4. As the aspect ratio of the magnetic material particles increases, the specific surface area of ​​the magnetic material also increases, and the contact area of ​​the magnetic material with the matrix material becomes large. Accordingly, during processing of the magnetic cladding layer 8 made of the matrix material containing the magnetic material, deposits are formed, and these deposits are easily scattered and exfoliated. However, if the aspect ratio of the magnetic material is limited to not more than 4 so that the specific surface area is small, deposits are unlikely to be formed during processing.In order to further improve the effect of suppressing deposits, the aspect ratio of the magnetic material is preferably set to not more than 3, and more preferably not more than 2.

[0043] Since the higher the aspect ratio, the greater the noise shielding effect of the magnetic cladding layer 8, the greater the aspect ratio of the particles of the magnetic material is, therefore, at least 1.5. As described above, the aspect ratio of the magnetic material is preferably set to not more than 2, particularly to enhance the scale suppression effect during the processing of the magnetic cladding layer 8, but when the priority is on improving the noise shielding effect, the aspect ratio may be set to more than 2. That is, the aspect ratio of the magnetic material can be selected in the range of not more than 4, depending on the required level for suppressing the occurrence of scale and shielding noise.

[0044] As described above, by using the magnetic material having particles with an average particle diameter of not more than 50 μm and an aspect ratio of not more than 4 as the material contained in the magnetic cladding layer 8, it is possible to suppress debris that disperses and peels off when the magnetic cladding layer 8 is subjected to mechanical processing such as cutting. When debris containing the magnetic material oozes out from the magnetic cladding layer 8, disperses, and peels off, there is a possibility that these debris may adhere to other components of the communication cable 1 or to external elements connected to the communication cable 1, such as a terminal, and impair the electrical connection and physical connection between the communication cable 1 and the external element.Even if the debris attached to any part of the communication cable 1 can be visually confirmed, the influence of the debris on the connection between the communication cable 1 and the external element can be ignored if the amount of debris occurrence is suppressed to such an extent that the exfoliation of the debris from the communication cable 1 is not visible. However, if a large amount of debris occurs and the amount of debris on the communication cable 1 reaches such an extent that the debris cannot remain on the surface of the communication cable 1 and falls off from the communication cable 1, the debris may have a significant impact on the connection between the communication cable 1 and the external element.

[0045] If deposits are present at a location where an electrical connection is formed, such as between the conductor 2 and the inner conductor terminal or between the braid layer 6 and the outer conductor terminal, the deposits may cause an increase in electrical resistance, and the connection may become loose. In addition, the physical connection may become unstable due to deposits located between the members in contact with each other. As the occurrence of deposits becomes more frequent, the material forming the deposits is lost from the magnetic cladding layer 8, which may lead to an adverse effect such as a reduction in workability when connecting the magnetic cladding layer 8 to the external member.If the occurrence of scale from the magnetic cladding layer 8 and the dispersion and exfoliation of the scale are suppressed, the above-described adverse effects due to scale can be prevented, and proper electrical connection and physical connection as well as processability at the time of connecting the communication cable 1 to the external member can be ensured.

[0046] In particular, when the communication cable 1 is configured such that the braid layer 6 is provided within the magnetic sheath layer 8 as described above, debris originating from the magnetic sheath layer 8 adheres to the braid layer 6 in a state of clogging its mesh and tends to be held in this state by the braid layer 6. However, by limiting the particle diameter and aspect ratio of the magnetic material in the magnetic sheath layer 8, the occurrence of debris is suppressed, so that the adhesion of the debris to the braid layer 6 can be effectively suppressed.As described above, as a result of performing the processing for removing the magnetic coating layer 8 at the terminal portion of the communication cable 1, the exposed braid portion 11 is formed, and the exposed braid layer 6 is connected to the terminal or the like. In the processing for forming the exposed braid portion 11, the debris from the magnetic coating layer 8 is unlikely to adhere to the exposed braid layer 6, so proper connection between the braid layer 6 and the terminal or the like is possible. Similarly, for the exposed conductor portion 12, since the attachment of the debris is suppressed, proper connection to the terminal or the like can be achieved.

[0047] In the magnetic cladding layer 8, the content of the magnetic material is not particularly limited, but in order to improve the noise shielding effect, the content may be set to at least 350 parts by mass per 100 parts by mass of the matrix material. On the other hand, in order to effectively suppress deposits from the magnetic cladding layer 8, the content may be set to not more than 750 parts by mass.

[0048] To improve noise shielding, the thickness of the magnetic sheath layer 8 can also be set to at least 0.2 mm. On the other hand, to avoid excessively increasing the diameter of the communication cable 1, the thickness must be 0.5 mm or less. The magnetic sheath layer 8 can also be formed by stacking multiple types of layers containing different types and amounts of magnetic material.

[0049] The degree of noise shielding provided by the magnetic cladding layer 8 can be adjusted by parameters such as the type, particle diameter, aspect ratio, density, and the like of the magnetic material to be used. The noise shielding effect can be evaluated in terms of the noise level when a signal is input to the communication cable 1, and as shown in the examples (described later), the parameters related to the magnetic material to be used can be selected so that the noise level is -100 dB or less, and further -110 dB or less. Outer sheath layer

[0050] An outer sheath layer 9 is a layer covering the outer periphery of the magnetic sheath layer 8 and exposed at the outer periphery of the entire communication cable 1. The outer sheath layer 9 contains no magnetic material except for unavoidable impurities.

[0051] The outer cladding layer 9 preferably contains a polymer material as its main component. Similar to the matrix material constituting the magnetic cladding layer 8, specific examples of the polymer material may include polyolefins such as polyethylene and polypropylene; halogen-based polymers such as polyvinyl chloride; engineering plastics such as polystyrene, polytetrafluoroethylene, and polyphenylene sulfide; various elastomers and rubbers. In view of excellent insulation and heat resistance, a polyolefin such as polypropylene or polyvinyl chloride is preferable. A single type of polymer material, or two or more types of polymer materials blended by blending, layering, or the like, may be used. The polymer material may be crosslinked or foamed. The magnetic cladding layer 8 may contain, in addition to the polymer material, an additive such as a flame retardant.

[0052] The polymer material from which the outer cladding layer 9 is formed can be identical to or different from the matrix material from which the magnetic cladding layer 8 is formed. Preferably, the polymer material forming the outer cladding layer 9 and the matrix material forming the magnetic cladding layer 8 are compatible with each other. Preferably, the two materials are formed from the same type of polymer material. Even more preferred is if the outer cladding layer 9 is formed from the same material as the magnetic cladding layer 8, with the difference that the material does not contain the magnetic material. If the magnetic cladding layer 8 is formed from a material in which the magnetic material is dispersed in the polypropylene, the outer cladding layer 9 can, for example, be formed from polypropylene that does not contain any magnetic material.

[0053] The outer cladding layer 9 functions to physically protect the magnetic cladding layer 8 and the components within the magnetic cladding layer 8 from contact with external substances and the like. Furthermore, there are some cases where the hardness of the magnetic cladding layer 8 increases due to the magnetic material contained therein, and damage such as cracks and breakages are likely to occur. In such cases, because the outer cladding layer 9 covers the magnetic cladding layer 8, even if damage such as cracks and breakages occur in the magnetic cladding layer 8, a case in which the damage progresses and forms a larger gap can be avoided.Accordingly, a situation where a gap is formed in a surface of the magnetic cladding layer 8 is unlikely to occur because the damage worsens and the electromagnetic wave escapes through the gap, thereby deteriorating the noise shielding property of the magnetic cladding layer 8. Since the magnetic cladding layer 8 is covered by the outer cladding layer 9, during processing of the magnetic cladding layer 8, cases where deposits originate from the magnetic cladding layer 8 and spread outward can be effectively avoided.When the polymer material constituting the outer cladding layer 9 is compatible and identical with the matrix material of the magnetic cladding layer 8, the contact between the outer cladding layer 9 and the magnetic cladding layer 8 becomes closer, and the effect of suppressing the occurrence and dispersion of the deposits from the magnetic cladding layer 8 due to the outer cladding layer 9 is particularly improved.

[0054] The thickness of the outer sheath layer 9 is not particularly limited, but in view of the particular improvement of the protective performance with respect to the magnetic sheath layer 8 and the effect of suppressing the dispersion of deposits, the thickness may be at least 0.1 mm. Further, the thickness of the outer sheath layer 9 may be equal to or greater than the thickness of the magnetic sheath layer 8. On the other hand, in order to avoid excessively increasing the diameter of the communication cable 1, the thickness of the outer sheath layer 9 may be 0.5 mm or less. Furthermore, the thickness of the outer sheath layer 9 may be twice that of the magnetic sheath layer 8 or less. Examples

[0055] Examples are described below. Note that the present invention is not limited to these examples. In the present examples, property evaluations are conducted at room temperature and in the atmosphere. Preparation of samples

[0056] A core wire was obtained by forming an insulating coating on the outer circumference of a conductor consisting of a twisted copper alloy wire using molded cross-linked polypropylene. The conductor cross-sectional area was set to 0.22 mm 2 and the thickness of the insulating layer was set at 0.195 mm. The outer diameter of the core wire was 0.85 mm.

[0057] A copper foil was arranged vertically on the outer periphery of the core wire as a metal foil. A braid layer was also formed on the outer periphery of the copper foil. The braid layer was formed as a single braid of tinned, annealed copper wire (TA wire).

[0058] A magnetic cladding layer was formed on the outer periphery of the mesh layer. A material obtained by mixing powder of the magnetic material with polypropylene, which serves as the matrix material, was extrusion-molded to a thickness of 0.25 mm. As shown in Table 1, the type, average particle diameter, aspect ratio, and content of the magnetic material were selected for each of Samples A1 to A6 and B1 to B3. For all samples, the outer diameter in the state where the magnetic cladding layer was formed was 2.7 mm.

[0059] Furthermore, for each of the samples, polypropylene, which does not contain any magnetic material, was extrusion-molded around the outer periphery of the magnetic sheath layer to form an outer sheath layer, thus completing a communication cable. The thickness of the outer sheath layer was set to 0.25 mm. The total diameter of the communication cable was 3.2 mm. Rating(1) Detachment property

[0060] The peeling properties of the manufactured communication cables were evaluated to estimate the extent of deposits occurring at the time of processing the magnetic sheath layer. Specifically, first, the outer sheath layer and the magnetic sheath layer were removed from the outer periphery of the braid layer to form the exposed braid portion at the end portion of each of the communication cables. Further, at a portion on the terminal side of the exposed braid portion, the braid layer, the copper foil, and the insulating coating were removed from the outer periphery of the conductor to form the exposed conductor portion. Through the above processing, the exposed portion in which the braid layer and the conductor were exposed in a stepped manner was formed at the end portion of the communication cable, as shown in Fig. 2 shown.

[0061] As described above, after the exposed portion was formed at the end portion of the communication cable, the exposed portion and its surroundings were visually inspected. If no debris originating from the magnetic sheath layer was attached to the communication cable or fell off the communication cable was found, the detachment property was rated as very high (+A). If debris was observed on the braid layer or conductor of the exposed portion, but the amount of debris formed was small and no debris fell off the communication cable was found, the detachment property was rated as high (A). If the amount of debris on the braid layer or conductor reached the extent that the debris fell off instead of remaining on the communication cable, the detachment property was rated as low (B). (2) Noise shielding capacity

[0062] The communication performance of the communication cable was evaluated by the noise level according to IEC 62153-4. During the measurement, the noise level at a signal input of 1.5 GHz was measured using a network analyzer for each of the communication cables according to the samples prepared as above. Results

[0063] Table 1 shows the compositions of the magnetic materials contained in the magnetic cladding layer and the evaluation results of the peeling properties and noise level for each of samples A1 to A6 and B1 to B3. In the table, the average particle diameter of the magnetic material indicates the D50 value of the equivalent circular diameter when observed by electron microscopy, and the content of the magnetic material is expressed in parts by mass per 100 parts by mass of the matrix material (polypropylene). [Table 1] Sample No. A1 A2 A3 A4 A5 A6 B1 B2 B3 Magnetic material in magnetic coating layer type Ni-Zn-Fernt Ni-Zn ferrite Ni-Zn ferrite Ni-Zn ferrite Ni-Zn ferrite Fe-Si-Al alloy Mn-Zn ferrite Fe-Si-Al alloy Fe-Si-Al alloy Average particle diameter 0,8 µm 12 µm 20 µm 12µm 20 µm 5 µm 60 µm 25 µm 45 µm Aspect ratio 2 2 2 3 4 2 2 5 5 Contents 700 pieces 700 pieces 700 pieces 700 pieces 700 pieces 700 pieces 700 pieces 330 pieces 330 pieces Detachment property A+ A+ A+ A A A+ B B B Noise level -110 dB -112 dB -115 dB -115 dB -115 dB -106 dB -109dB -107 dB -107 dB

[0064] According to Table 1, samples A1 to A6, in which the magnetic material in the magnetic cladding layer has a particle shape with an average particle diameter of no more than 50 μm and an aspect ratio of no more than 4, exhibit high peeling properties (A or A+) in both cases where the magnetic material is made of ferrite and Fe-Si-Al alloy. This means that the occurrence of deposits from the magnetic cladding layer is suppressed during terminal processing. In addition, the measured noise level is -105 dB or less, and high noise shielding is achieved by the magnetic cladding layer.

[0065] In contrast to these samples A1 to A6, sample B1, with an average particle diameter of the magnetic material of more than 50 μm, and samples B2 and B3, with an aspect ratio of more than 4, exhibit low detachment properties (B). That is, a large amount of debris originates from the magnetic coating layer, causing the debris to fall off the communication cable. In particular, for samples B2 and B3, which have a larger aspect ratio than samples A1 to A6, a large amount of debris was generated during terminal processing, even though the magnetic material content was reduced to half or less.In this way, by comparing the peeling properties of samples A1 to A6 and samples B1 to B3, it is confirmed that when particles with an average particle diameter of not more than 50 μm and an aspect ratio of not more than 4 are used as the magnetic material contained in the magnetic cladding layer, the occurrence of deposits during the processing of the magnetic cladding layer is suppressed.

[0066] Furthermore, comparing samples A2 to A5, samples A2 and A3 with a magnetic material aspect ratio of 3 or higher exhibit higher release properties (A+) compared to samples A4 and A5 with an aspect ratio of 2, and the occurrence of magnetic cladding layer deposits is greatly suppressed. This shows that in the range where the aspect ratio is not greater than 4, reducing the aspect ratio makes it possible to particularly effectively suppress the occurrence of magnetic cladding layer deposits. Although the particle diameters of the magnetic materials in samples A1 to A3 are different, all samples exhibit particularly high release properties (A+). LIST OF REFERENCE SYMBOLS 1 communication cable 2 conductors 3 Insulating coating 4 core wire 5 metal foil 6 braid layer 7 Metallic shielding layer 8 Magnetic coating layer 9 Outer sheath layer 10 Exposed section 11 Exposed braid section 12 Exposed conductor section

Claims

[1] Communication cable (1), comprising: a conductor (2); an insulating coating (3) covering the outer circumference of the conductor (2); and a magnetic coating layer (8) covering the outside of the insulating coating (3), wherein the magnetic cladding layer (8) contains a magnetic material, and the magnetic material has a particle shape with an average particle diameter of not more than 50 µm and an aspect ratio of at least 1.5 and not more than 4, wherein the average particle diameter is the D50 value of the equivalent circular diameter when observed by electron microscopy, and the magnetic cladding layer (8) contains no magnetic additive with an aspect ratio greater than 4 apart from unavoidable impurities. [2] Communication cable (1) according to claim 1, wherein the aspect ratio of the magnetic material is not greater than 2, and the magnetic cladding layer (8) contains no magnetic additive with an aspect ratio greater than 2 apart from unavoidable impurities. [3] Communication cable (1) according to claim 1 or 2, wherein in the magnetic cladding layer (8) the magnetic material is dispersed in a polymer material, and at least 350 parts by mass and at most 750 parts by mass of the magnetic material are contained per 100 parts by mass of the polymer material. [4] Communication cable (1) according to one of claims 1 to 3, further comprising: a braid layer (6) formed from a braided body of metal strands between the insulating coating (3) and the magnetic sheath layer (8). [5] Communication cable (1) according to claim 4, further comprising: an exposed braid section (11) in which the magnetic sheath layer (8) has been removed and the braid layer (6) is exposed. [6] Communication cable (1) according to claim 5, further comprising: an exposed conductor section (12) in which the magnetic sheath layer (8), the braid layer (6) and the insulating coating (3) have been removed and the conductor (2) is exposed. [7] Communication cable (1) according to one of claims 1 to 6, further comprising: an outer cladding layer (9) covering the outer periphery of the magnetic cladding layer (8) and containing no magnetic material. [8] A communication cable (1) according to claim 7, wherein the magnetic sheath layer (8) and the outer sheath layer (9) each contain polymer materials that are compatible with each other. [9] Communication cable (1) according to one of claims 1 to 8, wherein the average particle diameter of the magnetic material is not more than 15 µm.

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