Outdoor communication cable

Abstract

To provide an outdoor communication cable that is capable of retaining its outer form and is usable even under high-temperature environments.SOLUTION: An outdoor communication cable includes a cable core comprising insulated wires, a first sheath layer covering the cable core, and a second sheath layer that is disposed adjacent to the first sheath layer and covers the first sheath layer. The second sheath layer includes a metal laminate tape layer and an outermost layer that contains a heat-resistant resin composition and covers the metal laminate tape layer. The outermost layer has a Shore A hardness of 80 or more and 100 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an outdoor communication cable.

Background Art

[0002] Communication cables such as LAN (Local Area Network) cables are used for connecting various devices, such as between servers, between a server and a switch, and between a server and a personal computer. In recent years, communication cables suitable for high-speed data communication have been demanded. As such communication cables, cables with various structures have been developed. For example, a communication cable having a structure in which an inner sheath layer, a shielding layer, and an outer sheath layer are sequentially laminated on the outside of a cable core including a plurality of insulated electric wires has also been put into practical use (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a LAN twisted pair cable having an aggregate including a plurality of twisted pairs, a flame-retardant layer disposed on the outer periphery of the aggregate, and an outer sheath disposed on the outer periphery of the flame-retardant layer. The outer sheath in the LAN twisted pair cable described in Patent Document 1 is made of vinyl chloride resin, polyethylene resin, or the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in smelters and the like, the number of cases where surveillance cameras are installed outdoors as a security measure has been increasing. In smelters and the like, wiring may also be done in places where high-temperature environments occur. In this case, it is conceivable to use a heat-resistant resin such as a heat-resistant polyolefin resin as the material for the outer covering of the LAN twisted pair cable described in Patent Document 1. However, when such a heat-resistant resin is used, there is a risk that the external appearance shape may become defective.

[0006] Therefore, an object of the present invention is to provide an outdoor communication cable that can maintain its external appearance shape and can be used even in a high-temperature environment.

Means for Solving the Problems

[0007] According to one aspect of the present invention for solving the above problems, a cable core including insulated electric wires, a first outer covering layer covering the cable core, a second outer covering layer disposed adjacent to the first outer covering layer and covering the first outer covering layer, and having the second outer covering layer a metal laminate tape layer, an outermost layer including a heat-resistant resin composition and covering the metal laminate tape layer, and including the Shore A hardness of the outermost layer is 80 or more and 100 or less, an outdoor communication cable is provided.

Effects of the Invention

[0008] According to the present invention, an outdoor communication cable that can maintain its external appearance shape and can be used even in a high-temperature environment can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Modes for Carrying Out the Invention

[0010] Hereinafter, with reference to the attached drawings, an outdoor communication cable according to an embodiment of the present invention will be described. The outdoor communication cable of this embodiment (hereinafter, also simply referred to as "communication cable") is a communication cable composed of a so-called LAN (Local Area Network) twisted pair cable.

[0011] (Configuration of Outdoor Communication Cable) FIG. 1 is a cross-sectional view of an outdoor communication cable 10 according to an embodiment of the present invention.

[0012] As shown in FIG. 1, the outdoor communication cable 10 has a cable core 20, a first outer sheath layer 30, and a second outer sheath layer 40. In addition to the above configuration, the outdoor communication cable 10 may further have a wrapping layer 50 and a shielding layer 60. In this embodiment, the outdoor communication cable 10 has a cable core 20, a wrapping layer 50, a shielding layer 60, a first outer sheath layer 30, and a second outer sheath layer 40.

[0013] The cable core 20 has a plurality of twisted pairs 21. The number of twisted pairs 21 is not particularly limited as long as it is plural. In this embodiment, the number of twisted pairs 21 is four. Each twisted pair 21 has a configuration in which a plurality of (two in this embodiment) insulated wires 22 are twisted together in a certain direction. The insulated wire 22 has a conductor 23 and an insulating layer 24 covering the conductor 23.

[0014] The conductor 23 is a wire formed of a conductive metal material. The diameter of the conductor 23 is, for example, in the range of 0.5 mm or more and 0.6 mm or less.

[0015] The insulating layer 24 covers the conductor 23. The material of the insulating layer 24 is not particularly limited as long as it has insulating properties, and is, for example, a resin. From the viewpoint of improving the high-frequency electrical characteristics of the outdoor communication cable 10, the insulating layer 24 preferably contains a fluororesin composition. Examples of the fluororesin contained in the fluororesin composition include fluorinated ethylene-propylene copolymer (FEP; tetrafluoroethylene-hexafluoropropylene copolymer), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE). The insulating layer 24 is preferably composed of a fluorinated ethylene-propylene copolymer (FEP). The melt flow rate (test method: ASTM D2116, test temperature: 372 °C) of the resin (e.g., fluororesin) constituting the insulating layer is not particularly limited, but is preferably 20 g / 10 min or more and 45 g / 10 min or less. When the melt flow rate is less than 20 g / 10 min, the extrusion processability may deteriorate. On the other hand, when the melt flow rate exceeds 45 g / 10 min, the variation in the outer diameter may increase. The thickness of the insulating layer 24 is not particularly limited. The thickness of the insulating layer 24 is, for example, in the range of 0.2 mm or more and 0.3 mm or less.

[0016] The winding layer 50 covers the cable core 20. The winding layer 50 keeps the distance between the conductor 23 of the cable core 20 and the shielding layer 60 constant. The type of the winding layer 50 is not particularly limited as long as it can exhibit the above functions. For example, the winding layer 50 may be composed of a polyester non-woven tape or an extrusion coating layer (inner coating layer). Note that the winding layer 50 may not be provided.

[0017] When the winding layer 50 is made of a polyester non-woven fabric tape, the winding method of the polyester non-woven fabric tape is not particularly limited. The polyester non-woven fabric tape may be wound horizontally or may be attached vertically. In the present embodiment, the winding method of the polyester non-woven fabric tape is horizontal winding. Specifically, the polyester non-woven fabric tape is wound in a spiral while being overlapped with a tape wound around the side edge portion of the tape first.

[0018] When the winding layer 50 is composed of an extrusion coating layer, the winding layer 50 may be, for example, a layer obtained by extrusion coating polyethylene. At this time, the thickness of the extrusion coating layer is, for example, in the range of 0.2 mm or more and 0.4 mm or less. When the extrusion coating layer is formed as the winding layer 50, the distance between the cable core 20 and the first metal laminate tape layer 61 described later is likely to be constant, and the high-frequency electrical characteristics of the outdoor communication cable 10 and the like are likely to be good.

[0019] The shielding layer 60 is disposed between the cable core 20 and the first outer covering layer 30. The shielding layer 60 mainly protects the cable core 20 and blocks electromagnetic waves from the outside. In the present embodiment, the shielding layer 60 covers the winding layer 50. The shielding layer 60 has a first metal laminate tape layer 61 and a braided wire 62. Note that the shielding layer 60 may not be disposed.

[0020] The first metal laminate tape layer 61 covers the winding layer 50. The first metal laminate tape layer 61 blocks electromagnetic waves from the outside. The first metal laminate tape layer 61 is composed of a metal laminate tape. Examples of the metal laminate tape include an Al / PET tape in which an aluminum foil (Al) is attached to a polyethylene terephthalate resin substrate (PET). In the present embodiment, the metal laminate tape of the first metal laminate tape layer 61 is an Al / PET tape. The winding method of the first metal laminate tape layer 61 is not particularly limited. The first metal laminate tape layer 61 may be wound horizontally or may be attached vertically.

[0021] The braided wire 62 covers the first metal laminate tape layer 61. The braided wire 62 blocks external electromagnetic waves and also blocks the leakage of electromagnetic waves from the inside. The strands constituting the braided wire 62 are, for example, tinned soft copper wires with an outer diameter of 0.1 mm.

[0022] The first outer sheath layer 30 covers the cable core 20. The first outer sheath layer 30, together with the second outer sheath layer 40 described later, protects the cable core 20. In the present embodiment, since there are a winding layer 50 and a shielding layer 60 between the cable core 20 and the first outer sheath layer 30, the first outer sheath layer 30 covers the shielding layer 60 (braided wire 62). The first outer sheath layer 30 preferably contains a heat-resistant resin composition from the viewpoint of improving the heat resistance of the outdoor communication cable 10. For example, the first outer sheath layer 30 is preferably a solidified product of a thermoplastic resin composition having heat resistance. In the present specification, the heat-resistant resin composition means a resin composition that satisfies the physical properties specified in Table 1 below in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581. The tensile speed of the tensile test is 200 mm / min.

Table 1

[0023] Examples of the heat-resistant resin composition include a heat-resistant polyvinyl chloride resin composition and a heat-resistant polyolefin resin composition. The heat-resistant polyvinyl chloride resin composition and the heat-resistant polyolefin resin composition will be described separately later. In the present embodiment, the first outer sheath layer 30 is composed of a heat-resistant polyvinyl chloride resin composition or a heat-resistant polyolefin resin composition. The thickness of the first outer sheath layer 30 is not particularly limited. The thickness of the first outer sheath layer 30 is, for example, in the range of 0.3 to 1.0 mm.

[0024] The second outer covering layer 40 is disposed adjacent to the first outer covering layer 30 and covers the first outer covering layer 30. Together with the above-described first outer covering layer 30, the second outer covering layer 40 protects the cable core 20 from impacts, friction, ultraviolet rays, moisture, etc. applied to the outdoor communication cable 10 when used outdoors or indoors. The second outer covering layer 40 contains a heat-resistant resin composition from the viewpoint of improving the heat resistance of the outdoor communication cable 10. In the present embodiment, the second outer covering layer 40 has a drain wire 41, a second metal laminate tape layer (referred to as "metal laminate tape layer" in the claims) 42, and an outermost layer 43.

[0025] The drain wire 41 functions as an earth wire. The drain wire 41 is, for example, a tinned soft copper wire within the range of an outer diameter of 0.2 to 0.5 mm.

[0026] The second metal laminate tape layer 42 covers the drain wire 41. The second metal laminate tape layer 42 blocks moisture from the outside. The second metal laminate tape layer 42 is composed of a metal laminate tape. Examples of the metal laminate tape include an Al / PE tape in which an aluminum foil (Al) is attached to a polyethylene resin substrate (PE), and an Al / PET tape in which an aluminum foil (Al) is attached to a polyethylene terephthalate resin substrate (PET). In the Al / PET tape, it is preferable that an adhesive layer is formed on the surface (the surface on the outermost layer 43 side) opposite to the surface to which the aluminum foil (Al) of the polyethylene terephthalate resin substrate (PET) is attached. The type of the adhesive constituting the adhesive layer is not particularly limited, but an adhesive having a strong adhesive force to the heat-resistant polyvinyl chloride resin composition is preferable. Examples of the adhesive having a strong adhesive force to the heat-resistant polyvinyl chloride resin composition include polyester-based adhesives. As will be described later, when the outermost layer 43 contains a heat-resistant polyolefin resin composition, by using an Al / PE tape as the second metal laminate tape layer 42, the adhesion between the polyethylene resin substrate (PE) of the second metal laminate tape layer 42 and the outermost layer 43 can be improved. Further, when the outermost layer 43 contains a heat-resistant polyvinyl chloride resin composition, by using an Al / PET / adhesive layer tape as the second metal laminate tape layer 42, the adhesion between the adhesive layer (for example, a polyester-based adhesive layer) of the second metal laminate tape layer 42 and the outermost layer 43 can be improved. In the present embodiment, the metal laminate tape of the second metal laminate tape layer 42 is an Al / PE tape or an Al / PET / adhesive layer tape. The winding method of the second metal laminate tape layer 42 is not particularly limited. The second metal laminate tape layer 42 may be wound horizontally or attached vertically.

[0027] The outermost layer 43 covers the second metal laminate tape layer 42. The outermost layer 43 contains a heat-resistant resin composition from the viewpoint of improving the heat resistance of the outdoor communication cable 10. For example, the outermost layer 43 is a solidified product of a heat-resistant thermoplastic resin composition. As described above, in this specification, the heat-resistant resin composition means a resin composition that satisfies the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581. The tensile speed of the tensile test is performed at 200 mm / min. Examples of the heat-resistant resin composition include a heat-resistant polyvinyl chloride resin composition and a heat-resistant polyolefin resin composition. In the present embodiment, the outermost layer 43 is composed of a heat-resistant polyvinyl chloride resin composition or a heat-resistant polyolefin resin composition. The heat-resistant resin composition constituting the outermost layer 43 may be of the same type as or different from the heat-resistant resin composition constituting the first outer coating layer 30. Preferably, the type of the heat-resistant resin composition constituting the outermost layer 43 is the same as that of the heat-resistant resin composition constituting the first outer coating layer 30. That is, when the first outer coating layer 30 contains a heat-resistant polyolefin resin composition, the outermost layer 43 preferably contains a heat-resistant polyolefin resin composition. At this time, the composition of the heat-resistant polyolefin resin composition constituting the first outer coating layer 30 may be the same as or different from the composition of the heat-resistant polyolefin resin composition constituting the outermost layer 43. Also, when the first outer coating layer 30 contains a heat-resistant polyvinyl chloride resin composition, the outermost layer 43 preferably contains a heat-resistant polyvinyl chloride resin composition. At this time, the composition of the heat-resistant polyvinyl chloride resin composition constituting the first outer coating layer 30 may be the same as or different from the composition of the heat-resistant polyvinyl chloride resin composition constituting the outermost layer 43. The thickness of the outermost layer 43 is, for example, in the range of 1.0 to 2.0 mm. When the thickness of the outermost layer 43 is less than 1.0 mm, the strength cannot be maintained. On the other hand, when the thickness of the outermost layer 43 exceeds 2.0 mm, the cost becomes high.

[0028] The shore hardness (shore A hardness) measured using indenter type A in accordance with JIS K 7215:1986 (Test method for durometer hardness of plastics) of the outermost layer 43 is 80 or more and 100 or less. When the shore A hardness of the outermost layer 43 is less than 80, appearance defects will occur due to external factors such as shaking and vibration during extrusion processing. At the same time, the adhesion of the outermost layer 43 to the second metal laminate tape layer 42 will also decrease. On the other hand, when the shore A hardness of the outermost layer 43 exceeds 100, extrusion processing becomes difficult. Note that the shore A hardness represents the shore hardness when using indenter type A in the durometer hardness test method. Also, when the shore A hardness exceeds 90, indenter type A is used. The Shore A hardness of the outermost layer 43 can be adjusted by changing the composition of the heat-resistant resin composition that constitutes the outermost layer 43. For example, the Shore A hardness of the outermost layer 43 may be adjusted by changing the ratio of the heat-resistant resin to the flame retardant.

[0029] The heat-resistant polyolefin resin composition that constitutes the outermost layer 43 and / or the first outer coating layer 30 contains a polyolefin resin (PO). The polyolefin resin is not particularly limited as long as it is a resin composed of a polymer obtained by polymerizing or copolymerizing a compound having an ethylenic unsaturated bond. Known polyolefin resins used in heat-resistant resin compositions can be used as the polyolefin resin. Examples of the polyolefin resin include resins composed of polymers such as polyethylene, polypropylene, ethylene-α-olefin copolymers, polyolefin copolymers having an acid copolymer component or an acid ester copolymer component, rubbers or elastomers (excluding ethylene rubber) of these polymers, and styrenic elastomers. The content of the polyolefin resin in the heat-resistant polyolefin resin composition is preferably in the range of 10% by mass or more and 90% by mass or less. If the content of the polyolefin resin is not within the above range, the effects of the appearance shape and adhesion may not be obtained.

[0030] The polyolefin resin is preferable because it has high receptivity to various inorganic fillers such as metal hydrates and can maintain mechanical strength even when a large amount of inorganic filler is blended. In addition, these polyolefin resins can suppress a decrease in withstand voltage, particularly withstand voltage characteristics at high temperatures, while ensuring heat resistance. The polyolefin resin may be used alone or in combination of two or more.

[0031] Polyethylene is not particularly limited as long as it is a polymer containing an ethylene component as a constituent component. Examples of polyethylene include a homopolymer consisting only of ethylene, a copolymer of ethylene and an α-olefin (excluding propylene) of 5 mol% or less, and a copolymer of ethylene and a non-olefin of 1 mol% or less having only carbon, oxygen, and hydrogen atoms in the functional group. As the α-olefin and non-olefin, known ones conventionally used as copolymer components of polyethylene can be used. Examples of polyethylene that can be used in the present invention include high-density polyethylene (HDPE), low-density polyethylene (LDPE), ultra-high molecular weight polyethylene (UHMW-PE), linear low-density polyethylene (LLDPE), and very low-density polyethylene (VLDPE). Polyethylene, linear low-density polyethylene, and low-density polyethylene are preferred. Polyethylene may be used alone or in combination of two or more.

[0032] Polypropylene is not particularly limited as long as it is a polymer containing propylene as a constituent component. Examples of polypropylene include, in addition to a homopolymer of propylene, ethylene-propylene copolymers such as random polypropylene and block polypropylene as copolymers. Here, "random polypropylene" refers to a copolymer of propylene and ethylene having an ethylene component content of 1 to 5% by mass. Also, "block polypropylene" refers to a composition containing a homopolypropylene and an ethylene-propylene copolymer, having an ethylene component content of about 5 to 15% by mass, and in which the ethylene component and the propylene component exist as independent components. Polypropylene may be used alone or in combination of two or more. Examples of ethylene-α-olefin copolymers include copolymers of ethylene and α-olefins having 3 to 12 carbon atoms (excluding those included in polyethylene and polypropylene).

[0033] The ethylene-α-olefin copolymer is preferably a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms (excluding those contained in polyethylene and polypropylene). Examples of the ethylene-α-olefin copolymer include ethylene-propylene copolymers (excluding those contained in polypropylene), ethylene-butylene copolymers, and ethylene-α-olefin copolymers synthesized in the presence of a single-site catalyst. The ethylene-α-olefin copolymer may be used alone or in combination of two or more.

[0034] Examples of the acid copolymer component or acid ester copolymer component in the polyolefin copolymer having an acid copolymer component or acid ester copolymer component include carboxylic acid compounds such as (meth)acrylic acid, and acid ester compounds such as vinyl acetate and alkyl (meth)acrylate.

[0035] Here, the number of carbon atoms of the alkyl group of the alkyl (meth)acrylate is preferably in the range of 1 to 12. Examples of the alkyl group of the alkyl (meth)acrylate include methyl group, ethyl group, propyl group, butyl group, and hexyl group. Examples of the polyolefin copolymer having an acid copolymer component or acid ester copolymer component (excluding those contained in polyethylene) include ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid alkyl copolymer. The polyolefin copolymer having an acid copolymer component or acid ester copolymer component (excluding those contained in polyethylene) is preferably ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, or ethylene-butyl acrylate copolymer, and more preferably ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer from the viewpoints of the acceptability of the inorganic filler and heat resistance. The polyolefin copolymer having an acid copolymer component or acid ester copolymer component may be used alone or in combination of two or more.

[0036] A styrenic elastomer is a polymer having an aromatic vinyl compound as a constituent in the molecule. In the present embodiment, if the polymer contains an ethylene constituent in the molecule and also contains an aromatic vinyl compound constituent, it is classified as a styrenic elastomer. Examples of styrenic elastomers include compounds composed of block copolymers and random copolymers of a conjugated diene compound and an aromatic vinyl compound, or hydrogenated products thereof. Examples of the constituent of the aromatic vinyl compound in the polymer include styrene, p-(tert-butyl)styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, and vinyltoluene. The constituent of the aromatic vinyl compound in the polymer is preferably a styrene constituent. The constituent of the aromatic vinyl compound may be used alone or in combination of two or more.

[0037] The constituent of the conjugated diene compound is preferably a butadiene constituent. The constituent of the conjugated diene compound may be used alone or in combination of two or more. Further, as the styrenic elastomer, an elastomer composed of a polymer containing a constituent of an aromatic vinyl compound other than styrene and not containing a styrene constituent may be used by the same production method.

[0038] In the styrenic elastomer, the content of the styrene constituent is preferably 30% or more. If the content of the styrene constituent is too small, the oil resistance may decrease or the abrasion resistance may decrease. Examples of the styrenic elastomer include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), hydrogenated SIS, hydrogenated styrene-butadiene rubber (HSBR), and hydrogenated acrylonitrile-butadiene rubber (HNBR). As the styrenic elastomer, commercially available products can be used. Examples of commercially available products of the styrenic elastomer include Septon 4077, Septon 4055, Septon 8105 (all manufactured by Kuraray Co., Ltd.), Dynaron 1320P, Dynaron 4600P, 6200P, 8601P, 9901P (all manufactured by JSR Corporation).

[0039] The polyolefin resin may be acid-modified. For example, as the styrenic elastomer, those partially or entirely modified with an unsaturated carboxylic acid or those not modified at all can be used. The acid used for acid modification is not particularly limited. Examples of the acid used for acid modification include unsaturated carboxylic acids or their derivatives. Examples of the unsaturated carboxylic acid include maleic acid, itaconic acid, and fumaric acid. Examples of the derivative of the unsaturated carboxylic acid include maleic acid monoester, maleic acid diester, maleic anhydride, itaconic acid monoester, itaconic acid diester, itaconic anhydride, fumaric acid monoester, fumaric acid diester, and fumaric anhydride. As the derivative of the unsaturated carboxylic acid, maleic acid and maleic anhydride are preferable. The amount of acid modification is in the range of 0.1 to 7% by mass per molecule of the acid-modified polyolefin resin.

[0040] The heat-resistant polyvinyl chloride resin composition constituting the outermost layer 43 and / or the first coating layer 30 contains (A) polyvinyl chloride resin (PVC), (B) plasticizers ((B1) trimellitic acid-based plasticizers, (B2) pyromellitic acid-based plasticizers), (C) fillers, and (D) stabilizers.

[0041] (A) Polyvinyl chloride resin (PVC) The polyvinyl chloride resin is a homopolymer or copolymer of vinyl chloride and is not particularly limited as long as it is a vinyl chloride-based resin generally used for wire coating. The polyvinyl chloride resin may be a partially cross-linked resin. Also, a polymer blend of polyvinyl chloride resins, for example, a polymer blend composed of polyvinyl chloride resin and polyvinylidene chloride, may be used. Among these, a vinyl chloride homopolymer is preferred. Monomers copolymerizable with vinyl chloride are not particularly limited. Examples of monomers copolymerizable with vinyl chloride include ethylene, propylene, acrylonitrile, vinyl acetate, maleic acid or its ester, acrylic acid or its ester, methacrylic acid or its ester, vinylidene chloride, and the like.

[0042] (B) Plasticizers The heat-resistant polyvinyl chloride resin composition preferably contains, as plasticizers, (B1) trimellitic acid-based plasticizers and (B2) pyromellitic acid-based plasticizers. Examples of trimellitic acid-based plasticizers include alkyl trimellitates. Examples of pyromellitic acid-based plasticizers include alkyl pyromellitates. The alkyl groups constituting these alkyl esters are not particularly limited, but are alkyl groups having 1 or more carbon atoms, preferably 2 to 20 carbon atoms. The alkyl group may be either a linear alkyl or a branched alkyl.

[0043] Trimellitic acid and pyromellitic acid each have three and four carboxyl groups, respectively. These carboxyl groups react with an alcohol to form an alkyl ester. Therefore, generally, trimellitic acid alkyl esters and pyromellitic acid alkyl esters used as plasticizers both have a plurality of alkyl esters in one molecule. These plurality of alkyl esters may be the same or different. Also, the hydrogen constituting the alkyl group may be substituted. The substituent is not particularly limited and may be, for example, various functional groups or halogen elements. Examples of trimellitic acid alkyl esters include tri-(2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, tri-n-nonyl trimellitate, tri-n-decyl trimellitate, tri-iso-octyl trimellitate, tri-iso-nonyl trimellitate, tri-iso-decyl trimellitate, trimellitic acid·mixed linear alkyl, etc. Trimellitic acid·mixed linear alkyl has a plurality of types of linear alkyl groups (for example, a combination of two or three types of normal octyl group, normal nonyl group, normal decyl group) in one molecule. Examples of pyromellitic acid alkyl esters include tetra-(2-ethylhexyl) pyromellitate, tetra-n-octyl pyromellitate, tetra-n-nonyl pyromellitate, tetra-n-decyl pyromellitate, tetra-iso-octyl pyromellitate, tetra-iso-nonyl pyromellitate, tetra-iso-decyl pyromellitate, pyromellitic acid·mixed linear alkyl, etc. Pyromellitic acid·mixed linear alkyl has a plurality of types of linear alkyl groups (for example, a combination of 2 to 4 types of normal octyl group, normal nonyl group, normal decyl group) in one molecule.

[0044] The blending amount of the total plasticizer is preferably 55 to 65 parts by mass with respect to 100 parts by mass of the polyvinyl chloride resin. When the blending amount of the plasticizer is less than 55 parts by mass, the polyvinyl chloride resin composition is too hard and lacks flexibility. On the other hand, when the blending amount of the plasticizer exceeds 65 parts by mass, the polyvinyl chloride resin composition is too soft and easily deformed.

[0045] In this embodiment, an alkyl trimellitate and an alkyl pyromellitate are mixed and used. At this time, a combination of an alkyl trimellitate using only a linear alkyl group and an alkyl pyromellitate using an alkyl group having a side chain is preferable. From this viewpoint, the alkyl trimellitate is preferably, for example, tri-n-octyl trimellitate or mixed linear alkyl trimellitate. On the other hand, the alkyl pyromellitate is preferably, for example, tetra-(2-ethylhexyl) pyromellitate, tetra-isooctyl pyromellitate, tetra-isononyl pyromellitate, or tetra-isodecyl pyromellitate. The ratio of the trimellitic acid-based plasticizer (alkyl trimellitate) to the pyromellitic acid-based plasticizer (alkyl pyromellitate) is not particularly limited, but is preferably "0.8:1.0" to "1.2:1.0", and more preferably "0.95:1.0" to "1.05:1.0".

[0046] (C) Filler The filler is not particularly limited, and may be, for example, an inorganic filler. Examples of the inorganic filler include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zinc oxide, zeolite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, carbon fiber, and the like. Among these, calcium carbonate is preferable. During the production of the heat-resistant polyvinyl chloride resin composition and during use at high temperatures, calcium carbonate adsorbs and captures free ions, improving the electrical properties of the outdoor communication cable 10. If free ions remain in the heat-resistant polyvinyl chloride resin composition, the electrical insulation may decrease. The content of calcium carbonate is preferably 15 to 25 parts by mass with respect to 100 parts by mass of the polyvinyl chloride resin.

[0047] (D) Stabilizer In this embodiment, the heat-resistant polyvinyl chloride resin composition also contains a stabilizer. The stabilizer is not particularly limited, and examples thereof include barium-zinc-based (hereinafter referred to as Ba-Zn-based) stabilizers and calcium-zinc-based (hereinafter referred to as Ca-Zn-based) stabilizers. These stabilizers can be used in the form of organic acid compounds (such as stearates). The blending amount of the stabilizer is not particularly limited, but it is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the polyvinyl chloride resin. If the blending amount of the stabilizer is less than 1 part by mass, the heat stability of the resulting polyvinyl chloride resin composition deteriorates. On the other hand, if the blending amount exceeds 15 parts by mass, the mechanical properties deteriorate.

[0048] The heat-resistant polyolefin resin composition and the heat-resistant polyvinyl chloride resin composition may contain a flame retardant substance in addition to the above configuration. Examples of the flame retardant substance include antimony compounds (e.g., antimony trioxide (Sb 2 O 3 )), metal hydroxides (e.g., magnesium hydroxide), phosphorus-based flame retardants, nitrogen-containing compound flame retardants such as melamine-based and guanidine-based, inorganic compound flame retardants such as borates and molybdenum compounds, and halogen-based flame retardants. For example, the heat-resistant polyolefin resin composition may contain 20% by mass or more and 80% by mass or less of magnesium hydroxide. Further, the heat-resistant polyvinyl chloride resin composition may contain more than 0% by mass and 10% by mass or less of antimony trioxide.

[0049] In addition to the above configuration, the heat-resistant polyolefin resin composition and the heat-resistant polyvinyl chloride resin composition may further contain additives such as ultraviolet absorbers, antioxidants, antistatic agents, light stabilizers, carbon black, and colorants.

[0050] (Effect) As described above, according to the present invention, the outdoor communication cable 10 has a Shore A hardness of the second outer coating layer 40 of 80 or more and 100 or less, so that the appearance shape and the adhesion are good, and it is also suitable for use in a high-temperature environment.

Example

[0051] Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples in any way, and the embodiments can be changed without departing from the spirit of the present invention.

[0052] 1. Production of Outdoor Communication Cable · Cable 1 (Example 1) A single wire with an outer diameter of 0.565 mm was prepared as a conductor. A fluororesin composition containing fluorinated ethylene - propylene copolymer (FEP) was extruded from the die of an extruder to coat the conductor with an insulating layer, obtaining an insulated wire. Two insulated wires were twisted together to form a pair - twisted wire, and four pair - twisted wires were twisted together to obtain a cable core. A polyester non - woven fabric tape was wound horizontally around the cable core to form a pressed winding layer. An Al / PET tape (the first metal laminate tape layer) was wound horizontally on the pressed winding layer, and further, a tinned soft copper wire with an outer diameter of 0.1 mm was braided on it to form a shielding layer. A heat - resistant polyvinyl chloride resin composition was extruded from the die of an extruder to form a first outer covering layer with a thickness of 0.4 mm around the shielding layer. The heat - resistant polyvinyl chloride resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581. An Al / PE tape (the second metal laminate tape layer) was attached longitudinally on the first outer covering layer, and further, a heat - resistant polyolefin resin composition containing low - density polyethylene (LDPE) and magnesium hydroxide as a flame - retardant substance was extruded from the die of an extruder to form an outermost layer with a thickness of 1.3 mm, obtaining Cable 1. At this time, the Shore A hardness of the outermost layer measured in accordance with JIS K 7215:1986 (Plastic Durometer Hardness Test Method) was 80. The heat - resistant polyolefin resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0053] · Cable 2 (Example 2) Cable 2 was obtained in the same manner as cable 1, except that the Al / PE tape (the second metal laminate tape layer) was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 80.

[0054] · Cable 3 (Example 3) Cable 3 was obtained in the same manner as cable 1, except that the content ratio of low-density polyethylene and the flame retardant in the heat-resistant polyolefin resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 90. Also, the heat-resistant polyolefin resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0055] · Cable 4 (Example 4) Cable 4 was obtained in the same manner as cable 3, except that the Al / PE tape (the second metal laminate tape layer) was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 90.

[0056] · Cable 5 (Example 5) Cable 5 was obtained in the same manner as cable 1, except that the content ratio of low-density polyethylene and the flame retardant in the heat-resistant polyolefin resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 100. Also, the heat-resistant polyolefin resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0057] · Cable 6 (Example 6) Cable 6 was obtained in the same manner as cable 5, except that the Al / PE tape (the second metal laminate tape layer) was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 100.

[0058] · Cable 7 (Comparative Example 1) Cable 7 was obtained in the same manner as Cable 1, except that the content ratio of low-density polyethylene and the flame retardant in the heat-resistant polyolefin resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 78. Also, the heat-resistant polyolefin resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0059] · Cable 8 (Comparative Example 2) Cable 8 was obtained in the same manner as Cable 7, except that the Al / PE tape (the second metal laminate tape layer) was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 78.

[0060] · Cable 9 (Example 7) Cable 9 was obtained in the same manner as Cable 1, except that an Al / PET / polyester-based adhesive layer tape was vertically attached instead of the Al / PE tape as the second metal laminate tape layer, and a heat-resistant polyvinyl chloride resin composition containing polyvinyl chloride and magnesium hydroxide as the flame retardant was used instead of the heat-resistant polyolefin resin composition as the resin composition for forming the outermost layer. At this time, the Shore A hardness of the outermost layer measured by the method described above was 80. Also, the heat-resistant polyvinyl chloride resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0061] · Cable 10 (Example 8) Cable 10 was obtained in the same manner as Cable 9, except that the Al / PET / adhesive layer tape (the second metal laminate tape layer) was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 80.

[0062] · Cable 11 (Example 9) A cable 11 was obtained in the same manner as cable 9, except that the content ratio of polyvinyl chloride and the flame retardant in the heat-resistant polyvinyl chloride resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 90. Also, the heat-resistant polyvinyl chloride resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0063] · Cable 12 (Example 10) A cable 12 was obtained in the same manner as cable 11, except that the Al / PET / adhesive layer tape (second metal laminate tape layer) with an adhesive layer formed was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 90.

[0064] · Cable 13 (Example 11) A cable 13 was obtained in the same manner as cable 9, except that the content ratio of polyvinyl chloride and the flame retardant in the heat-resistant polyvinyl chloride resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 100. Also, the heat-resistant polyvinyl chloride resin composition satisfied all the physical properties specified in Table 1 above in all heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0065] · Cable 14 (Example 12) A cable 14 was obtained in the same manner as cable 13, except that the Al / PET / adhesive layer tape (second metal laminate tape layer) with an adhesive layer formed was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 100.

[0066] · Cable 15 (Comparative Example 3) Cable 15 was obtained in the same manner as cable 9, except that the content ratio of polyvinyl chloride and the flame retardant substance in the heat-resistant polyvinyl chloride resin composition for forming the outermost layer was changed. At this time, the Shore A hardness of the outermost layer measured by the method described above was 78. Also, the heat-resistant polyvinyl chloride resin composition satisfied all the physical properties specified in Table 1 above in all the heat resistance tests at 80°C, 90°C, 105°C, and 125°C according to UL1581.

[0067] · Cable 16 (Comparative Example 4) Cable 16 was obtained in the same manner as cable 15, except that the Al / PET / adhesive layer tape (the second metal laminate tape layer) having an adhesive layer formed thereon was wound horizontally. At this time, the Shore A hardness of the outermost layer measured by the method described above was 78.

[0068] 2. Evaluation of Cables · Evaluation of Appearance Shape For each cable after production, it was visually confirmed whether there was any abnormality in the appearance. The visual results were evaluated according to the following criteria. (Evaluation Criteria) ○: The appearance shape was smooth. ×: The appearance shape was not smooth.

[0069] · Evaluation of Adhesion The second metal laminate tape layer and the outermost layer were cut out from each cable to obtain strip-shaped samples (width 1 cm, length approximately 20 cm). Then, the second metal laminate tape layer was partially peeled off from the outermost layer, and the adhesive force when peeling the outermost layer and the second metal laminate tape layer at a tensile speed of 100 mm / min was measured. The measurement results were evaluated according to the following criteria. (Evaluation Criteria) ○: 9.8 N / 10 mm or more ×: Less than 9.8 N / 10 mm · Evaluation of Electrical Characteristics under Heat Cycle The return loss margin under heat cycle was measured in a manner compliant with TIA Cat5e Permanent Link. Specifically, after leaving the cable in an atmosphere at -20°C for 1 hour, the return loss margin of the cable was measured. Next, after leaving the same cable in an atmosphere at +20°C for 1 hour, the same measurement was performed on the cable. Next, after leaving the same cable in an atmosphere at +125°C for 1 hour, the same measurement was performed on the cable. Next, after leaving the same cable in an atmosphere at +20°C for 1 hour, the same measurement was performed on the cable. The above combination of measurements was repeated 5 times. The measurement results were evaluated according to the following criteria. (Evaluation Criteria) ○: The return loss margin is 0 dB or more in all measurements ×: The return loss margin is less than 0 dB in any of the measurements

[0070] 2. Evaluation Results For each cable, based on the results of the evaluation of the external appearance shape, the adhesion, and the electrical characteristics under heat cycle, a comprehensive evaluation was performed as follows. Evaluation Criteria 〇: Pass in all three evaluations ×: Fail in any of the three evaluations

[0071] Table 2 shows the results of the evaluation of the external appearance shape, the adhesion, and the electrical characteristics under heat cycle, and the comprehensive evaluation.

[0072]

Table 2

[0073] As shown in Table 2, in Cables 1 to 6 and 9 to 14 according to the examples where the Shore A hardness of the second outer sheath is 80 or more and 100 or less, the appearance shape, adhesion, and electrical characteristics under heat cycle were good. This is presumably because the Shore A hardness of the second outer sheath was within a predetermined range and thus not affected by external factors. On the other hand, in Cables 7, 8, 15, and 16 according to the comparative examples where the Shore A hardness of the second outer sheath is less than 80 (78), the appearance shape, adhesion, and electrical characteristics under heat cycle were poor. This is presumably because the low Shore A hardness caused the cables to be affected by external factors during molding.

Industrial Applicability

[0074] The outdoor communication cable of the present invention is useful in various fields as a communication cable that can be used outdoors.

Explanation of Symbols

[0075] 10 Outdoor communication cable 20 Cable core 21 Twisted pair 22 Insulated wire 23 Conductor 24 Insulation layer 30 First outer sheath 40 Second outer sheath 41 Drain wire 42 Second metal laminate tape layer 43 Outermost layer 50 Winding layer 60 Shielding layer 61 First metal laminate tape layer 62 Braided wire

Claims

1. a cable core including an insulated wire; a first jacket layer covering the cable core; a second jacket layer disposed adjacent to the first jacket layer and covering the first jacket layer; having The second jacket layer is A metal laminate tape layer; an outermost layer that contains a heat-resistant resin composition and covers the metal laminate tape layer; Including, The Shore A hardness of the outermost layer is 80 or more and 100 or less. Outdoor communication cable.

2. 2. The outdoor communication cable according to claim 1, 2. An outdoor communication cable, wherein the heat-resistant resin composition is a heat-resistant polyolefin resin composition or a heat-resistant polyvinyl chloride composition.

3. 2. The outdoor communication cable according to claim 1, 13. An outdoor communication cable, comprising: a shielding layer disposed between said cable core and said first jacket layer.

4. 2. The outdoor communication cable according to claim 1, The insulated wire includes a conductor and an insulating layer covering the conductor, 13. An outdoor communication cable, wherein the insulating layer contains a fluororesin composition.

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