JPH10321053A - cable - Google Patents

Abstract

(57) [Abstract] [Problem] Used for automobiles, robots, electronic devices, etc.
An object of the present invention is to provide a cable which is excellent in air-tightness and water-tightness at a connection portion with a terminal connected to a terminal, can prevent corrosion of a cable conductor and performance degradation of connected equipment parts, and is particularly excellent in water resistance. SOLUTION: In a cable provided with a coating layer on the outside of a multi-core stranded wire in which a plurality of insulated conductors are twisted, at least the outermost layer of the coating layer is (a) 20 to 95% by weight of a thermoplastic polyester elastomer and (b) ) A cable formed of a resin composition containing 80 to 5% by weight of a styrene- (ethylene-propylene) -based block copolymer as a base resin, and having been subjected to a cross-linking treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable used for automobiles, robots, electronic devices, and the like, and more particularly, to a cable having excellent mechanical properties and flexibility. A cable suitable for being molded with a thermoplastic resin such as polybutylene terephthalate (hereinafter also referred to as PBT) resin or polyamide resin in order to keep the connection portion airtight or watertight after being connected to a terminal or the like. Things.

[0002]

2. Description of the Related Art Thermoplastic polyurethane-based compositions having good mechanical properties and flexibility are used as insulating coating materials for cables used in automobiles, robots, electronic equipment and the like. Then, after molding, the thermoplastic polyurethane composition has heat resistance by crosslinking treatment by irradiation with ionizing radiation,
Chemical resistance and water resistance may be improved. When connecting a component such as a sensor or an electrode terminal to such a cable, the connection portion and the surrounding area thereof are formed airtight or watertight with a resin mold (molded body) for protection. In order to secure airtightness and watertightness with a resin mold as described above, PBT resin or polyamide resin is often used as a mold material because of ease of molding and excellent mechanical strength.

[0003]

However, depending on the selection of the covering material of the cable and the molding material, the difference in the heat shrinkage between the materials causes the formation of the cable in the heating and cooling process during the terminal processing or use. There is a gap at the body interface,
There is a problem that moisture infiltrates from a gap generated at the interface. If moisture invades from the gap created at the interface, the conductors of the cable will corrode and the performance of the connected equipment parts will deteriorate, and other problems will occur.Therefore, various seals are required to maintain airtightness and watertightness. Countermeasures are required. For this reason, the workability at the time of terminal processing becomes extremely complicated, and the work required a high degree of skill.

In order to solve such a problem, it is conceivable that the covering material of the cable is made of the same or similar material as the molding material in consideration of the adhesiveness with the mold material. Has poor moldability as a cable covering material, and also has a problem in flexibility required for electric wires. In addition, even if the coating material has satisfactory initial adhesion to the molding material, air-tightness and water-tightness are impaired in the heat shock test, and materials that exhibit characteristic deterioration in the water resistance test are practical in the long term. Not a target. An object of the present invention is to maintain the air-tightness and water-tightness of the interface between a cable and a molded body for a long period of time without taking any special sealing measures for maintaining air-tightness and water-tightness. An object of the present invention is to provide a cable that can prevent corrosion of a conductor and performance degradation of connected equipment parts and has excellent water resistance.

[0005]

The present inventors have made intensive studies to achieve the above object, and as a result, as a base resin of a coating material, a single component, which has little adhesion to a molding material, has little adhesion. The inventors have found that by using a styrene-based elastomer in combination with a thermoplastic polyester elastomer, it is possible to obtain an adhesive property that greatly exceeds the adhesive strength of the thermoplastic polyester elastomer alone, and completed the present invention. That is, in the present invention, (1) In a cable provided with a coating layer on the outside of a multi-core stranded wire in which a plurality of insulated conductors are twisted, at least the outermost layer of the coating layer is made of (a) a thermoplastic polyester elastomer 20 (B) a cable formed of a resin composition containing 80 to 5% by weight of a styrene- (ethylene-propylene) -based block copolymer as a base resin and (b) a cross-linked cable; (2) The cable according to (1), wherein the coating layer includes two layers, and a resin composition containing a thermoplastic polyurethane as a base resin is used for an inner layer thereof. (3) The coating layer includes two layers. And an inner layer having a density of 0.86 to 0.90 g / cm3, selected from the group consisting of ethylene / α-olefin copolymer and ethylene / vinyl acetate copolymer. Both base one - characterized by using a resin composition to scan resin according to (1) cable, is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the cable of the present invention, one or more coating layers may be provided on a multifilamentary stranded wire obtained by twisting insulated conductors. When a plurality of layers are formed, they may be coated by simultaneous extrusion, or the next outer layer may be sequentially coated after the inner layer is coated. At this time, at least the outermost layer of the coating layer is (a) a thermoplastic polyester elastomer 20 to
It is formed from a resin composition containing 95% by weight and (b) 80 to 5% by weight of an ethylene- (ethylene-propylene) -based block copolymer as a base resin.

An embodiment of the present invention will be described below. FIG. 1 is a schematic sectional view showing an embodiment of a cable according to the present invention, wherein 1 is a multi-core stranded wire, and the multi-core stranded wire 1 is a conductor (for example, 20 tinned soft copper wires having an outer diameter of 0.18 mmφ are stranded). A plurality of (two in FIG. 1) insulated conductors having an insulating layer 1b made of polyethylene, polyvinyl chloride, or the like are provided on a stranded wire conductor 1a having a conductor diameter of 1 mmφ. ing. 2 is a coating layer covering the multi-core stranded wire 1,
The coating layer 2 is a layer obtained by appropriately cross-linking a resin composition containing the above (a) and (b) as a base resin.

The coating layer provided on the outer side of the multi-core stranded wire is preferably a multilayer of two or more layers in order to increase the roundness of the cable cross section. FIG. A plurality of coating layers 2 (two layers in FIG. 2) for covering the wire 1 are provided, and the inner layer 2a is a resin composition containing a thermoplastic polyurethane as a base resin, or a density of 0.86 to 0.90 g /
It can be formed of a resin composition containing at least one selected from the group consisting of an ethylene / α-olefin copolymer and an ethylene / vinyl acetate copolymer having a base resin of cm 3. This inner layer may be an appropriately crosslinked layer.
The outer layer 2b of the coating layer is composed of a layer obtained by appropriately cross-linking the resin composition using the above (a) and (b) as a base resin. In the cable of the present invention, since the outermost layer of the coating layer provided on the multifilamentary stranded wire is formed by a crosslinked body of a specific resin composition, the cable coating material and the molding material (molded body) at the cable end portion Air-tightness at the interface between the cable and the molding material (molded product), which results in receiving a high temperature and a high pressure when molding the resin at the end of the cable, or as a result of repeated heating and cooling during use, The problem of poor watertightness is solved.

[0009] The base resin in the resin composition constituting at least the outermost layer of the coating layer of the cable of the present invention is the aforementioned (a)
And (b) as main components. The thermoplastic polyester elastomer (a) used in the present invention is a thermoplastic elastomer having flexibility, and includes a hard segment composed of a crystalline polyester such as polybutylene terephthalate and a polyoxymethylene such as polytetramethylene ether glycol. Glycol,
Alternatively, it is a block copolymer with a soft segment comprising a polyester glycol such as polycaprolactone glycol. Examples of such a thermoplastic polyester elastomer include “Hytrel” (trade name, manufactured by Toray Dupont), “Perprene” (trade name, manufactured by Toyobo Co., Ltd.), “Arnitel” (trade name, manufactured by Akzo), and the like. Is commercially available and can be appropriately selected from various grades of commercially available products.

The styrene- (ethylene-propylene) block copolymer (b) used in the present invention comprises a polystyrene block (S) and an ethylene-propylene elastomer block (EP) having a flexible polyolefin structure.
It is a block copolymer based on two types, a diblock type and a triblock type consisting of a terminal styrene block. At room temperature, it has excellent rubber elasticity,
It is a resin with excellent oil resistance, heat resistance and low temperature characteristics. As such a product, for example, “Septon” (trade name, manufactured by Kuraray Co., Ltd.) is commercially available and can be appropriately selected from various grades of commercially available products. S- used in the present invention
The EP block copolymer by itself has almost no adhesive strength to an injection molding material such as a PBT resin or a polyamide resin at all. However, by compounding within a specific compounding amount range with the thermoplastic polyester elastomer,
It exhibits surprising adhesion, which is far greater than the adhesion of thermoplastic polyester elastomers alone to molding materials.

The amount of component (a) in the base resin of the resin composition used in the present invention is in the range of 20 to 95% by weight, preferably 40 to 60% by weight. When the amount of the component (a) is within this range, the adhesiveness between the outermost layer of the cable and the molding material is good, and not only water tightness and air tightness can be ensured, but also good water resistance. The blending amount of the component (b) in the base resin is 80 to 5% by weight, preferably 60 to 40%.
% By weight. When the amount exceeds 80% by weight,
The adhesive strength between the outermost layer of the cable and a molding material such as a PBT resin or a polyamide resin is greatly reduced, and water tightness and air tightness cannot be maintained. On the other hand, when the compounding amount is less than 5% by weight, not only the adhesive strength between the outermost layer of the cable and the molding material is low, but also the water resistance is reduced and the watertightness and airtightness are impaired. In addition, (a) + (b)
Other resin components such as thermoplastic elastomers (thermoplastic polyurethane, polyamide elastomer, etc.) and ethylene copolymers (ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, etc.) are blended within a range not to impair the properties of the above. be able to.

It is preferable that the coating layer provided on the outside of the multi-core stranded wire is a multilayer of two or more layers in order to increase the roundness of the cable cross section. Of the multilayer coating layer, the coating material of the inner layer is:
It is selected in consideration of the adhesion to the outermost coating layer, etc.
In particular, a thermoplastic polyurethane composition having a density of 0.86
A resin composition comprising a base resin of any one of an ethylene / α-olefin copolymer and an ethylene / vinyl acetate copolymer having a weight of 0.99 g / cm 3 or a mixture thereof is preferred.

When a thermoplastic polyurethane resin composition is used as the inner layer coating material, it is possible to improve the repetitive flexibility of the cable. Examples of the type of thermoplastic polyurethane resin serving as a base resin include polyester-based urethane resins (adipate, caprolactone-based, and polycarbonate-based) and polyetherether-based urethane resins, and polyether-based resins in terms of water resistance and mold resistance. Urethane resins are preferred.

The coating material for the inner layer has a density of 0.8.
It is preferable to use a resin composition containing at least one selected from the group consisting of an ethylene / α-olefin copolymer and an ethylene / vinyl acetate copolymer having a weight of 6 to 0.90 g / cm 3 as a base resin. With these resins,
A cable can be formed at low cost while maintaining the airtightness between the inner layer and the outer layer and the repeated bending characteristics. The ethylene / α-olefin copolymer is composed of ethylene and propylene,
-Butene, 4-methyl-1-pentene, 1-hexene,
1-octene, 1-decene, a copolymer with at least one kind of α-olefin such as 1-dodecene,
From the viewpoint of elasticity, in the present invention, the density is 0.86 to 0.86.
It is preferably 0.90 g / cm3.

Further, the ethylene / vinyl acetate copolymer which can be used for the inner layer of the coating layer preferably has a vinyl acetate content of 10 to 30% by weight from the viewpoint of crosslinkability and elasticity. The ethylene / α-olefin copolymer and the ethylene / vinyl acetate copolymer can be used alone or as a mixture of both. The heat resistance of the resin composition constituting the inner layer can be improved by crosslinking, and when molding with a resin having a high melting point, such as polybutylene terephthalate or polyamide, the resin composition is preferably crosslinked. The heat resistance and rubber elasticity can be improved by crosslinking the coating layer, and as a result, the elastic repulsive force of the cable insulating layer, that is, the air-tightness and water-tightness of the interface with the molded body molded into the terminal in order to improve the restoring force. Is improved.

As a method for crosslinking the coating layer, a conventionally known crosslinking method using ionizing radiation or a chemical crosslinking method can be adopted, but from the viewpoint of productivity, a crosslinking method using irradiation with ionizing radiation such as an electron beam is preferable. . The dose of the electron beam is 1 to 30
Mrad is appropriate. In the case of the chemical crosslinking method,
Using a resin composition containing an organic peroxide as a crosslinking agent, crosslinking is completed by heat treatment after extrusion molding.

The resin composition used for the outermost layer of the coating layer is as follows:
The heat resistance, chemical resistance, and water resistance can be further improved by appropriately crosslinking, but the gel fraction is 5%.
At ５０50%, the improvement in adhesiveness and heat resistance is most recognized. If the amount is less than 5% by weight, the effect of crosslinking such as melting of the cable coating layer in a high temperature atmosphere of 200 ° C. or more is not recognized. If the content exceeds 50% by weight, the adhesiveness, which is the object of the present invention, is reduced, resulting in impaired airtightness and watertightness.

The resin composition constituting the coating layer of the cable according to the present invention contains various additives generally used in insulated wires and cables, such as antioxidants, metal deactivators, and flame retardants. , Dispersants, colorants, fillers,
A lubricant and the like can be appropriately compounded within a range that does not impair the purpose of the present invention. In particular, the addition of a flame retardant is indispensable for automotive applications.

Examples of the antioxidant include amines such as 4,4'-dioctyl diphenylamine, N, N'-diphenyl-p-phenylenediamine, and a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline. -Based antioxidant, pentaerythrityl-tetrakis (3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate),
Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4)
Phenolic antioxidants such as -hydroxybenzyl) benzene, bis (2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl) sulfide, 2-mercaptobenzimidazole and the like Examples thereof include zinc salts and sulfur-based antioxidants such as pentaerythritol-tetrakis (3-lauryl-thiopropionate).

Examples of the metal deactivator include N, N'-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, 3- (N-salicyloyl) amino-1, 2,4-triazole, 2,2′-oxamidobis- (ethyl 3-((3,5-di-t-butyl-
4-hydroxyphenyl) propionate) and the like.

As the flame retardant, tetrabromobisphenol A (TBA), decabromodiphenyl oxide (DBDPO), octabromodiphenyl ether (O
BDPE), hexabromocyclododecane (HBC
D), bistribromophenoxyethane (BTBP)
E), halogens such as tribromophenol (TBP), ethylenebistetrabromophthalimide, TBA / polycarbonate oligomer, ★ brominated polystyrene, ★ brominated epoxy, ethylenebispentabromodiphenyl, chlorinated paraffin, dodecachlorocyclooctane, etc. Inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, phosphoric acid compounds, polyphosphate compounds,
And phosphorus-based flame retardants such as red phosphorus compounds. Examples of the flame retardant aid and filler include carbon, clay, zinc oxide, tin oxide, magnesium oxide, molybdenum oxide, antimony trioxide, silica, talc, calcium carbonate, magnesium carbonate, zinc borate and the like.

[0022]

【Example】

(Examples 1 to 13, Comparative Examples 1 and 2) Conductor (conductor diameter 1 mm)
φ tinned soft copper stranded wire Composition: 20 / 0.18mm
On top of φ), low-density polyethylene was extrusion-coated so as to have an outer diameter of 1.7 mm, and irradiated with an electron beam having an acceleration voltage of 500 keV and a dose of 20 Mrad to obtain an insulated conductor having a crosslinked polyethylene insulating layer. A multi-core stranded wire was prepared by twisting two of these insulated conductors. Then, using a 40 mmφ extruder (L / D = 25) on the multi-core stranded wire, a die temperature of 180 ° C., and then to a feeder side C3 = 170 ° C.
Resin of any of (A) thermoplastic polyurethane, (B) ethylene-vinyl acetate copolymer, and (C) ethylene-α olefin copolymer shown in the table under the conditions of C2 = 160 ° C. and C1 = 150 ° C. Was extruded to an outer diameter of 4.2 mm to form an inner coating layer, and the outer layer resin composition shown in Table 2 was further coated thereon with the same outer layer as an outer diameter of 5.0 mm. Extrusion coated under conditions. Next, after extrusion coating, the coating layer was cross-linked by irradiating an electron beam with an acceleration voltage of 750 keV and the irradiation dose shown in the table, to obtain a cable having two coating layers as shown in FIG. In Example 13, the inner coating layer was formed of the same material as the outer coating material.

Various characteristics of the obtained cables were evaluated by the following test methods, and the results are shown in Tables 1 to 3. 1) Gel fraction of the outer layer Only the outer layer was collected from the cable, and it was heated at 110 ° C with xylene.
Extract for 24 hours, dry thoroughly and weigh. The weight remaining after melting was defined as a gel content and expressed as a percentage of the weight before solvent extraction.

2) Peel strength from PBT resin or polyamide resin and presence or absence of residue after peeling a) The coating layer of a cable of a predetermined length is divided into two in the longitudinal direction, the insulated conductor is removed, and The circular coating layer was set in a mold, and c) PBT resin or polyamide (PA) resin (nylon 12) was injected into the mold to perform resin molding on the coating layer. The obtained resin molded body was subjected to a peel test. In the peeling test, the cable coating layer was peeled off from the resin molded body at an angle of 90 degrees at a speed of 50 mm / min, and the maximum strength at that time was measured. It was observed whether it was.
The case where the coating material was destroyed by cohesive force and remained on the surface of the molded body was evaluated as ○, the case where a small amount of the coating material remained, and the case where it did not remain as ×.

3) Airtightness of Terminal As shown in FIG. 3, the covering layers 2 and 1b of the cable were removed to expose the conductor 1a, and the electrode terminal 5 was connected to the end. Next, the connection portion and the vicinity thereof were covered with a resin molded body 4 by molding (injection molding) using PBT resin. About this cable, 120 degreeC x 1 hour, -40
C. × 1 hour as one cycle, 100 cycles, 50 cycles
A zero cycle heat shock test was performed. Thereafter, compressed air of 2 atm was injected from the terminal opposite to the resin molded body side, and immersed in water to check for leakage from the resin molded body side, and airtightness was confirmed by the presence or absence of bubbles. The test was performed on 5 samples, and when all the samples passed, the results were evaluated as ○,
When any of the samples was rejected, it was evaluated as x.

4) Water resistance From the cable sample, only the outer skin was cut in half and collected.
I punched it with an 8-inch dumbbell. The punched sample was polished so that the surface became smooth and immersed in hot water at 90 ° C. for 240 hours. The immersed sample is subjected to a tensile test at a constant speed type tensile tester at a distance of 20 mm between the marked lines and at a pulling speed of 500 mm / min. Tensile strength at break (TS) and elongation at break (El)
Was measured. The TS and El before hot water immersion were set to 10
It was expressed as a percentage assuming 0%. 5) Airtightness after immersion The sample before the heat shock test prepared in 3) was immersed in hot water under the same conditions as in 4), and then the same airtightness test as in 3) was performed. The number of tests was 3, and was evaluated as ○ when all the samples passed, and × when at least one of them failed.

6) Heat resistance A metal rod having the same diameter (5.0 mmφ) as the cable sample
It was left at 200 ° C. for 30 minutes while being wound for more than one turn.
After being taken out and sufficiently cooled at room temperature, it was visually confirmed that there was no crack or melting on the cable surface. Perform a three-sample test, and if all samples have no melting or cracks,
When even one sample melted or cracked, it was evaluated as x.

The following components were used as the components shown in Tables 1 to 3. (01) Polyester elastomer manufactured by Toray Dupont, trade name: Hytrel 2300X
06 (02) SEPS manufactured by Kuraray Co., Ltd., trade name: Septon 2063 (styrene content 13% by weight, hardness 34 (JIS-A) (03) SEPS manufactured by Kuraray Co., Ltd., trade name: Septon 2002 (styrene content 30 wt. %, Hardness 80 (JIS-A) (04) SEP Kuraray Co., Ltd., trade name: Septon 1001 (styrene content 35% by weight, hardness 80 (JIS-A) (05) pentaerythrityl-tetrakis (3- ( 3,
5-Di-t-butyl-4-hydroxyphenyl) propionate) Ciba Geigy Co., Ltd., trade name: Irganox 101
0 (06) Ethylene bispentabromophenyl Albemarle Co., Ltd., trade name: Cytex 8010

(A) Thermoplastic polyurethane resin (elastomer) manufactured by Nippon Miractran Co., Ltd., trade name: E-385PNA
T (B) Ethylene / vinyl acetate copolymer Mitsui-Dupont Polychemical Co., Ltd., trade name: Evaflex V527-4 (vinyl acetate content 17% by weight, MFR 0.8 g / 10 min., Density 0.
94 g / cm3 (C) Ethylene / α-olefin copolymer Dow Chemical Co., Ltd., trade name: Engage CL8
003 (α-olefin (octene) content 18% by weight,
MFR 1 g / 10 min. , Density 0.89g / cm3

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

From the results shown in Tables 1 to 3, the outermost layer of the coating layer was formed of a resin composition containing (a) 20 to 95% by weight of a polyester elastomer and (b) 80 to 5% by weight of SEPS or SEP as a base resin. It can be seen that the cable of the example of the present invention has excellent adhesiveness between the cable covering material and the molded article, maintains the airtightness of the cable end, and has sufficient water resistance. In particular, when the outermost layer is formed of a resin composition containing (a) component (40-60% by weight) and (b) component (60-40% by weight) as a base resin, the adhesiveness is extremely good. When the crosslinking treatment is performed so that the fraction becomes 5 to 50% by weight, it can be seen that heat resistance is sufficient in addition to the above effects.

On the other hand, as can be seen from the results of the comparative examples shown in Table 3, in Comparative Example 1 in which the component (b) is out of the range specified in the present invention, the PBT resin and the polyamide resin were used. Adhesion is reduced and sufficient airtightness cannot be obtained (Comparative Example 1). In the case of less than the specified range, that is, in Comparative Example 2 in which only the component (a) was used, the adhesiveness to the mold material was not so high as in the example, so that the airtightness as the initial characteristics was obtained. When the number of cycles increases, not only the airtightness is lost, but also the water resistance is extremely poor, and the airtightness cannot be maintained after immersion in hot water.

[0035]

The cable of the present invention comprises (a) 20 to 95% by weight of a thermoplastic polyester elastomer and (b)
The terminal portion of the cable is made of PBT since it is formed of a resin composition containing 5-80% by weight of a styrene- (ethylene-propylene) -based block copolymer as a base resin.
When molding with a thermoplastic resin such as a resin or polyamide resin, the cable covering material and the molding material are firmly adhered to each other, so that the cable and the molded body can be bonded without any special sealing measures. Air-tightness and water-tightness of the interface are maintained for a long time,
Corrosion of the conductor of the insulated wire inside the cable and deterioration of the performance of connected equipment parts can be prevented. Furthermore, since the cable of the present invention has a coating material having extremely excellent water resistance, heat resistance, and extruding properties, it is stable over time as a wiring cable for automobiles, robots, electronic devices, and the like. Can be used.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a cable according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the cable of the present invention.

FIG. 3 is an explanatory view showing an embodiment of a terminal portion of the cable of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-core stranded wire 1a Conductor 1b Insulating layer 2 Coating layer 2a Inner layer 2b Outer layer 3 Cable 4 Resin molding 5 Electrode terminal

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01B 3/42 H01B 3/42 E 7/28 7/28 E // C08L 53/00 C08L 53/00 67/02 67/02 (72) Inventor Ryoji Ohno 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd.

Claims (3)

[Claims] 1. A cable having a coating layer provided on the outside of a multifilamentary stranded wire obtained by twisting a plurality of insulated conductors, wherein at least the outermost layer of the coating layer comprises (a) 20 to 95% by weight of a thermoplastic polyester elastomer and ( b) 80 to 5% by weight of a styrene- (ethylene-propylene) block copolymer
A cable formed of a resin composition having a base resin as a base resin and subjected to a crosslinking treatment. 2. The cable according to claim 1, wherein said coating layer comprises two layers, and a resin composition containing thermoplastic polyurethane as a base resin is used for an inner layer thereof. 3. The coating layer is composed of two layers, and the inner layer has an ethylene • density of 0.86 to 0.90 g / cm 3.
2. The cable according to claim 1, wherein a resin composition comprising at least one base resin selected from the group consisting of an α-olefin copolymer and an ethylene / vinyl acetate copolymer is used.