Rubber-coated cable and manufacturing method thereof

Abstract

Provided are a rubber-coated cable and a method for manufacturing the same, the rubber-coated cable being provided with a core formed by twisting a plurality of electric wires in which a conductor is coated with an insulating layer, and a coating layer provided on the core, the coating layer being formed from a crosslinked product of an elastomer resin composition, the elastomer resin composition includes a mixture of a chlorine-based rubber and an ethylene-based copolymer, carbon black as a reinforcing agent, and a plasticizer, the chlorine-based rubber being selected from at least one of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. The ethylene-based copolymer is selected from at least one of an ethylene-alpha-olefin copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, a modified product of these copolymers, and a terpolymer of two monomers constituting these copolymers and other monomers, the maximum static friction coefficient between the coating layers is less than 1.0, the hardness is less than 85, and the thickness of the coating layers is less than 10 [mu] m. The weight ratio of the chlorine-based rubber to the ethylene-based copolymer is 70: 30 to 80: 20.

Description

[0001] This invention is a divisional application of the Chinese invention application with application number 201810130010.5, application date February 8, 2018, and invention name “Sheath Material and Cable”. Technical Field

[0002] The invention relates to a sheath material and a cable. Background Art

[0003] The cable comprises an electric wire and a coating layer (sheath layer) arranged on the outer periphery of the electric wire. The electric wire comprises a conductor and an insulating layer arranged on the outer periphery of the conductor, and the coating layer (sheath layer) is arranged on the outer periphery of the insulating layer. Thus, the coating layer (sheath layer) is arranged on the outermost periphery of the cable and is formed of an electrical insulating material mainly made of rubber or resin.

[0004] For example, Patent Document 1 discloses a wire covering resin composition containing a styrene-based thermoplastic elastomer, an ethylene-α-olefin resin, a silicone oil having a viscosity of 100 cs or less, a paraffin-based oil, and a fatty acid amide that is solid at room temperature.

[0005] Patent Document 2 discloses a technique for improving the sliding property between the insulating layer and the sheath layer or the insulating layer by adding silicone powder to a flame-retardant resin composition of at least one of the insulating layer or the sheath layer on the outer periphery of the conductor of a flat cable.

[0006] In addition, Patent Document 3 provides the following technology, namely: in a multi-core cable constructed by twisting insulating core wires (which are formed by covering the outer periphery of the conductor with a thermoplastic resin as an insulator), the thermoplastic resin contains a polyester elastomer, and a bending- and torsion-resistant cable is provided by containing 0.5 to 3.0 wt% of an organic high-molecular-weight silicone polymer.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2001-31903

[0010] Patent Document 2: Japanese Patent Application Publication No. 2003-7144

[0011] Patent Document 3: Japanese Patent Application Publication No. 2008-218061 Summary of the invention

[0012] Problems to be solved by the invention

[0013] As described above, since the coating (sheath) of the cable is a layer disposed on the outermost circumference of the cable, when the friction resistance is high, such as in the case of a rubber coating (sheath), wiring becomes difficult due to (1) contact between cables, (2) contact between cables and other objects, etc. In particular, in a cabtire cable used as a movable part cable to move with a connected device, when the friction resistance of the coating (sheath) is high, there are problems such as cable wrinkling, kinking and bending of the wires (core wires) inside the cable, and disconnection of the conductor inside the wire due to (1) contact between cables, (2) contact between cables and other objects.

[0014] In order to solve such problems, the above-mentioned silicone powder addition technology and silicone polymer mixing technology have been studied for the purpose of reducing the friction resistance of the coating layer (jacket layer), but they are still insufficient from the viewpoint of sliding property and mechanical characteristics.

[0015] An object of the present invention is to provide a sheath material and a cable having flexible mechanical properties that can be easily bent while maintaining slidability.

[0016] Means of solving problems

[0017] (1) A sheath material according to one aspect of the present invention is formed from a crosslinked product of an elastomeric resin composition, wherein the elastomeric resin composition comprises a mixture of a chlorinated rubber and an ethylene copolymer, wherein the chlorinated rubber is selected from at least one of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene, and the ethylene copolymer is selected from at least one of ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, modified products of these copolymers, and terpolymers of two monomers constituting these copolymers with other monomers, wherein the maximum static friction coefficient between the crosslinked products is less than 1.0, and the hardness measured by a type A durometer is less than 85.

[0018] For example, the weight ratio of the chlorine-based rubber to the ethylene-based copolymer is 40:60 to 80:20.

[0019] For example, the chlorine-based rubber is chlorinated polyethylene, and the ethylene-based copolymer is ethylene-vinyl acetate copolymer.

[0020] (2) According to another aspect of the present invention, the cable comprises a conductor, an insulating layer disposed around the conductor, and a coating layer disposed around the insulating layer; the coating layer is formed of a crosslinked product of an elastomeric resin composition, the elastomeric resin composition comprising a mixture of a chlorinated rubber and an ethylene copolymer, the chlorinated rubber being at least one selected from polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene, the ethylene copolymer being at least one selected from ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, modified products of these copolymers, and terpolymers of two monomers constituting these copolymers with other monomers, wherein the maximum static friction coefficient between the coating layers is less than 1.0, and the hardness measured by a type A durometer is less than 85.

[0021] For example, the weight ratio of the chlorine-based rubber to the ethylene-based copolymer is 40:60 to 80:20.

[0022] For example, the chlorine-based rubber is chlorinated polyethylene, and the ethylene-based copolymer is ethylene-vinyl acetate copolymer.

[0023] Effects of the Invention

[0024] By using the sheath material (electrical wire coating insulator) or the electric wire coating elastomer resin composition according to one aspect of the present invention as a cable coating layer, the slidability and mechanical properties of the cable can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a diagram showing a cable according to one embodiment of the present invention.

[0026] Figure 2 This is a diagram showing a method for measuring the maximum static friction coefficient.

[0027] Reference numerals

[0028] 2: electric wire, 3: coating (sheath), 21: conductor, 22: insulating layer, PL1: plate to which the cable is fixed, PL2: plate to which the cable is fixed, angle θ. DETAILED DESCRIPTION

[0029] 1. Elastomer resin composition

[0030] The elastomer resin composition (elastomer resin composition for wire coating) of the present embodiment contains chlorine rubber (chlorine polymer) and ethylene copolymer as base polymers. The weight ratio of chlorine rubber to ethylene copolymer is 40:60 to 80:20. The following materials can be used as chlorine rubber and ethylene copolymer.

[0031] 1.1 Chlorine rubber

[0032] As the chlorine-based rubber, for example, chlorinated polyethylene, chlorosulfonated polyethylene, chloroprene rubber, etc. can be used.

[0033] Chlorinated polyethylene can be obtained, for example, by preparing a powdered linear polyethylene (from high density to low density) into an aqueous suspension and blowing chlorine gas into the system at a temperature near the crystalline melting point of the raw polyethylene. Chlorinated polyethylene is obtained by a non-uniform system reaction, and its crystallinity can be controlled from amorphous rubber-like materials to semi-crystalline and crystalline plastic-like materials. Chlorinated polyethylene is a thermoplastic elastomer with a wide range of properties.

[0034] Chlorosulfonated polyethylene can be prepared, for example, by dissolving raw polyethylene in a solvent and subjecting the resulting polyethylene to chlorination and chlorosulfonation.

[0035] Chloroprene rubber refers to dry (solid) rubber, and is roughly divided into sulfur-modified and non-sulfur-modified types due to differences in molecular weight, uniformity, and types of stability regulators during polymerization.

[0036] Thus, by using chlorinated rubber, oil resistance can be improved, thereby preventing cable deterioration due to adhesion of oil such as machine oil.

[0037] The chlorine content of the chlorosulfonated polyethylene and the chlorinated polyethylene is preferably 30 to 40 wt%. The chlorine content refers to the mass % concentration of chlorine in the chlorosulfonated polyethylene or the chlorinated polyethylene. In addition, the chlorosulfonated polyethylene and the chlorinated polyethylene are preferably non-crystalline materials.

[0038] When chlorine content is less than 30wt%, there is a tendency that oil resistance decreases. In addition, when using chlorosulfonated polyethylene or chlorinated polyethylene with crystallization, there is a tendency that the addition of the plasticizer (oil) for regulating rubber hardness increases. In this way, if the addition of the plasticizer (oil) increases, tensile strength will be reduced. And, thus, there is also a problem of plasticizer (oil) overflowing during use. In addition, when chlorine content exceeds 40wt%, it becomes a property similar to polyvinyl chloride and becomes too hard. In addition, as described below, the compatibility with ethylene copolymer is reduced. Thus, there is a risk that the mechanical properties represented by tensile strength decrease.

[0039] 1.2 Ethylene copolymers

[0040] As the ethylene-based copolymer, there can be used ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, ethylene-acrylate copolymer, etc. These copolymers crystallize in a temperature range of about 25 to 60°C.

[0041] Ethylene-vinyl acetate copolymer (EVA for short) is a copolymer of ethylene and vinyl acetate (VA for short).

[0042] Ethylene-alpha olefin copolymers are copolymers of ethylene and alpha olefins.

[0043] Ethylene-acrylate copolymer is a copolymer of ethylene and acrylate. As acrylate, esterification materials of acrylic acid and alcohol can be cited, and as ethylene-acrylate copolymer, ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA) and the like can be used.

[0044] In addition, ethylene copolymers modified by polar functional groups can be used. Examples of polar functional groups include epoxy groups, carboxyl groups, and maleic anhydride groups. For example, ethylene-α-olefin copolymers modified by maleic anhydride groups can be used.

[0045] In addition, terpolymers of two monomers constituting copolymers such as ethylene-vinyl acetate copolymers, ethylene-α-olefin copolymers, and ethylene-acrylate copolymers and other monomers can be used. For example, terpolymers of ethylene, acrylate, and other monomers can be used. Examples of such terpolymers include ethylene-maleic anhydride-methyl acrylate copolymers and ethylene-maleic anhydride-ethyl acrylate copolymers.

[0046] Thus, by using a mixture of chlorinated rubber and ethylene copolymer as the base polymer, the maximum static friction coefficient can be reduced without significantly reducing the mechanical properties and oil resistance. In this case, similar to the case of adding silicone powder or the like to reduce the friction resistance of the base polymer itself to impart sliding properties, the friction resistance does not increase sharply with the use time, and the sliding properties can be maintained for a long time, which is useful.

[0047] Furthermore, as shown in the examples described below, when the weight ratio of chlorinated rubber to ethylene copolymer is 40:60 to 80:20, excellent properties are obtained. In addition, when ethylene-vinyl acetate copolymer is used as the ethylene copolymer, it has a little polarity and its compatibility with chlorinated rubber is increased. Thus, in this embodiment, for example, the compatibility is excellent compared to a mixed organic high molecular weight silicone polymer, and as a result, the mechanical properties can be improved.

[0048] In addition, the softness of the ethylene-vinyl acetate copolymer can be adjusted by adjusting the amount of vinyl acetate. It is particularly preferred that the amount of vinyl acetate in the ethylene-vinyl acetate copolymer is 25 to 35 wt%. When the amount of vinyl acetate is less than 25 wt%, it is slightly hard, and when it exceeds 35 wt%, its properties are similar to those of rubber, so the friction resistance tends to increase. The amount of vinyl acetate (vinyl acetate content) refers to the mass % concentration of vinyl acetate in the ethylene-vinyl acetate copolymer.

[0049] Various additives may be added to the above-mentioned base polymer as required. The additives will be described below.

[0050] 1.3 Cross-linking agent

[0051] In order to improve the heat resistance and oil resistance of the base polymer and improve the mechanical properties, it is preferred to crosslink the base polymer by adding sulfur compounds, organic peroxides, utilizing electron beam irradiation, silane grafting water crosslinking, etc. In the present embodiment, since ethylene polymers are used, it is preferred to crosslink by electron beam irradiation and organic peroxides. In order to improve the degree of crosslinking, it is particularly preferred to crosslink by organic peroxides. As a crosslinking agent, for example, organic peroxides such as 1,3-bis(2-tert-butylperoxyisopropyl)benzene and diisopropylbenzene peroxide (DCP) can be used. Further, in order to improve the degree of crosslinking, crosslinking aids such as triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and multifunctional monomers such as trimethylolpropane trimethacrylate (TMPT) can be used simultaneously. In addition, as a crosslinking aid, sulfur compounds such as ethylene thiourea, dibenzothiazole disulfide, and trimethylthiourea can also be used.

[0052] 1.4 Stabilizer

[0053] In order to suppress the degradation of the base polymer, a stabilizer may be used. Examples of the stabilizer include lead stabilizers such as tribasic lead sulfate, tin compounds, epoxy stabilizers, hydrotalcite, and Ca / Zn stabilizers.

[0054] In this embodiment, since the base polymer contains chlorinated rubber, it is particularly preferred to add a stabilizer that can capture hydrogen chloride. As such a stabilizer, hydrotalcite compounds, epoxy soybean oil, etc. can be used. By adding such a stabilizer, hydrogen chloride generated at high temperatures during processing or use can be captured.

[0055] 1.5 Reinforcement Materials

[0056] In order to improve the mechanical strength of the base polymer, a reinforcing agent may be used. As the reinforcing agent, carbon black may be used.

[0057] 1.6 Antioxidants

[0058] In order to inhibit the oxidation of the polymer, an amine antioxidant can be used. As an amine antioxidant, for example, diphenylamine compounds, quinoline compounds, etc. can be used. As diphenylamine compounds, diphenylamine derivatives (manufactured by Kawaguchi Chemical Industry Co., Ltd., ANTAGE DDA (trade name)) and the like can be listed. In addition, as quinoline compounds, 2,2,4-trimethyl-1,2-dihydroquinoline polymers (trade name: NOCRAC 224; JIS abbreviation TMDQ) and the like can be listed. These amine antioxidants can be used alone or in combination of two or more. In particular, diphenylamine compounds and quinoline compounds are suitable for capturing free radicals.

[0059] 1.7 Other additives

[0060] As other additives, flame retardants, lubricants, surfactants, softeners, plasticizers, inorganic fillers, compatibilizers, metal chelating agents (copper damage inhibitors), ultraviolet absorbers, light stabilizers, colorants, etc. can be used.

[0061] 2. Sheath material

[0062] The sheath material (electrical wire coating insulator) of the present embodiment is a crosslinked product of the above-mentioned elastomer resin composition (electrical wire coating elastomer resin composition). The above-mentioned elastomer resin composition is cured by crosslinking to become a sheath material.

[0063] For example, the elastomer resin composition is kneaded, extruded and coated around a core formed of an electric wire using an extruder, and then crosslinked to form a sheath material around the core. Kneading and extrusion can be performed using conventional equipment.

[0064] 3. Cable structure

[0065] Figure 1 It is a figure which shows the cable of this embodiment. Figure 1 (a) is a stereoscopic diagram showing the internal structure of the cable. Figure 1 (b) is a cross-sectional view.

[0066] like Figure 1 As shown, the cable of this embodiment has a plurality of ( Figure 1 The core is obtained by twisting 20 (20 in the figure) electric wires 2, and a coating layer (sheath layer) 3 is formed on the outer periphery thereof. The electric wire (core wire) 2 includes a conductor 21 and an insulating layer 22 covering the conductor 21. A spacer (not shown) or the like may be provided on the outer periphery of the core, and a coating layer (sheath layer) 3 may be provided on the outer periphery thereof.

[0067] The conductor 21 is formed of a conductive material such as copper or copper alloy (eg, tinned annealed copper wire) and has a predetermined conductor cross-sectional area. The conductor diameter of the conductor 21 is not particularly limited, and an optimal value can be appropriately selected according to the application.

[0068] As the material of the insulating layer 22, materials commonly used in cables can be used. As the insulating layer 22, for example, an ethylene-propylene rubber mixture can be used. In addition, as the insulating layer 22, a fluororesin (for example, ethylene-tetrafluoroethylene copolymer (ETFE) etc.) can be used. Fluororesin has excellent mechanical strength and sliding properties, and can reduce thickness. Thus, it is possible to achieve a thinner diameter of the cable.

[0069] The coating layer (sheath layer) 3 is formed of the above-mentioned elastomer resin composition. Specifically, it is composed of a sheath material which is a cross-linked product of the above-mentioned elastomer resin composition.

[0070] 4. Cable manufacturing method

[0071] Next, a method for manufacturing the cable according to the present embodiment will be described.

[0072] First, a plurality of electric wires 2 are prepared in which the conductor 21 is coated with the insulating layer 22. The plurality of electric wires 2 prepared are twisted to form a core (insulated electric wire). Next, the elastomer resin composition is extruded and coated around the core using an extruder or the like.

[0073] Next, the elastomer resin composition coated on the core is crosslinked (for example, by high-pressure steam at a predetermined temperature), thereby crosslinking the elastomer resin composition to form a coating layer (sheath layer) 3 on the outer periphery of the core. Thus, the cable of this embodiment is obtained. It should be noted that, here, the cable having a plurality of electric wires 2 is described, but in the case of a cable having a single electric wire 2, the coating layer (sheath layer) 3 can also be coated in the same manner.

[0074] Here, the maximum static friction coefficient between the insulators (insulating material, crosslinked product of the elastomer resin composition) constituting the above-mentioned coating layer (sheath layer) 3 is less than 1.0. In addition, the rubber hardness of the insulator constituting the above-mentioned coating layer (sheath layer) 3 measured by a type A durometer is less than 85.

[0075] Thus, according to this embodiment, an insulator formed by an elastomeric resin composition having a mixture of chlorine-based rubber and ethylene-based copolymer in a predetermined weight ratio as a base polymer is used as a coating layer (sheath layer) of a cable, thereby improving the sliding property and mechanical properties of the cable. Specifically, the maximum static friction coefficient between cables can be made lower than 1.0, which can improve the sliding property of the cable. Thus, the resistance during (1) contact between cables and (2) contact between cables and other objects is reduced, thereby simplifying the wiring of the cable. Furthermore, the rubber hardness of the coating layer (sheath layer) of the cable measured by a type A durometer can be made lower than 85, which can improve the mechanical properties. Specifically, the cable can be made easy to bend and become soft, making the wiring of the cable easy.

[0076] In particular, the sheath material formed by the elastomer resin composition of the present embodiment can not only maintain sliding properties, but also has a soft mechanical property that is easy to bend. Even when used as a coating layer (sheath layer) of a rubber-coated cable for a movable part cable that moves with a connected machine, it is possible to suppress the wrinkling of the cable. The "wrinkling" refers to the state in which the sheath material is twisted due to friction resistance generated by the contact between cables or the contact between cables and other objects, and the twisted wires (core wires) are tangled, resulting in a chaotic configuration. When the wires are operated in such a disordered state, the wires are unreasonably bent, and the core wires are twisted and buckled. According to the sheath material formed by the elastomer resin composition of the present embodiment, the above-mentioned wrinkling can be suppressed, the knotting and bending of the wires (core wires) inside the cable can be suppressed, and the disconnection of the conductor inside the wire can be avoided, thereby improving the characteristics of the cable.

[0077] Example

[0078] Hereinafter, the elastomer resin composition according to the present embodiment, the insulator obtained by crosslinking the elastomer resin composition, and the cable using the elastomer resin composition and the insulator are further described in detail with reference to examples. It should be noted that the present invention is not limited to the following examples.

[0079] The elastomer resin composition of each example was prepared by the following method and conditions.

[0080] Core Formation Steps:

[0081] First, prepare a plurality of tinned soft copper wires twisted together to form a 2.5 mm outer diameter and a 3.5 mm cross-sectional area. 2The conductor is coated with an insulating layer mixture by extrusion on the outer periphery of the conductor. As the mixture, an ethylene-propylene rubber copolymer mixture is used, and a thickness of 2.5 mm is extruded on the outer periphery of the conductor. Next, the mixture on the outer periphery of the conductor is cross-linked to obtain an electric wire (core wire). 20 of the electric wires (core wires) are twisted together with a spacer, and a single-sided rubber release cloth tape is wound thereon so that the rubber release surface is on the sheath side to obtain a core.

[0082] Mixing steps:

[0083] A mixed polymer of chlorinated rubber and ethylene copolymer as a base polymer and various additives (see Table 1) were put into a 55L Japan Moriyama kneader for kneading to obtain a compound. The kneaded compound was put into an extruder and extruded into a rope shape. The extruded material was water-cooled and then formed into pellets.

[0084] It should be noted that the following substances were used as base polymers (chlorinated rubber, ethylene copolymer) and additives. Specific trade names (manufacturing company names) are also shown in Table 1. In addition, the weight ratio of chlorinated rubber to ethylene copolymer and the amount of additives added are shown in Table 1. The amount of each additive is part by mass based on 100 parts by mass of the base polymer.

[0085] Chlorinated rubber…Chloroprene rubber, chlorosulfonated polyethylene (the chlorine content of chlorosulfonated polyethylene is 40 wt%), chlorinated polyethylene (the chlorine content of chlorinated polyethylene is 40 wt%)

[0086] Ethylene copolymers: ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers (the amount of vinyl acetate in the ethylene-vinyl acetate copolymer is 28 wt%), ethylene-acrylate copolymers (e.g., ethylene-ethyl acrylate copolymers)

[0087] Crosslinking agent…Dicumyl peroxide (DCP)

[0088] Crosslinking aid…Multifunctional monomer (trimethylolpropane trimethacrylate (TMPT))

[0089] Crosslinking aid…Vulcanization accelerator (ethylene thiourea)

[0090] Inorganic fillers…zinc oxide, magnesium oxide, talc

[0091] Stabilizers…epoxidized soybean oil, hydrotalcite compounds

[0092] Plasticizers…stearic acid, DINP (diisononyl phthalate), naphthenic processing oil

[0093] Antioxidants…Amine antioxidants 1, 2

[0094] Reinforcement agent…Carbon black

[0095] Extrusion steps:

[0096] The above compound (elastomer resin composition) was extrusion coated on the outer circumference of the core at a thickness of 2.8 mm, and lead was extrusion coated at the same time to form an intermediate of the cable.

[0097] Cross-linking steps:

[0098] The intermediate was wound on a drum and heated with saturated steam at 150°C for 120 minutes to crosslink the compound (elastomer resin composition) on the periphery of the core, thereby coating the periphery of the core with a sheath material. The lead remaining on the periphery of the sheath material was stripped off to obtain a cable with an outer diameter of 29 mm.

[0099] Table 1

[0100]

[0101] evaluate:

[0102] The cables were evaluated according to the tests and standards shown below.

[0103] (1) Tensile test

[0104] The prepared cables were subjected to a tensile test according to IEC60811-1-1. SE4 specified in IEC60254-1 issued by the International Electrical Standards Council was applied, and a tensile strength of 10 MPa or more was considered acceptable. In addition, a breaking elongation of 300% or more was considered acceptable.

[0105] (2) Durometer A hardness test

[0106] The sheath material is stripped from the cable and the surface roughness is smoothed by grinding. Three or less sheath materials are stacked so that the total thickness is 6 mm or more as a sample. The sample is measured using a type A durometer (rubber durometer) based on JIS K6253. A durometer A hardness of less than 85 is considered acceptable.

[0107] (3) Oil resistance

[0108] The prepared cables were subjected to an oil resistance test based on IEC60811-2-1. SE4 specified in IEC60254-1 issued by the International Electrical Standards Council was applied, and IRM902 oil was used as the impregnation oil. After immersion at an oil temperature of 100°C for a specified time, the residual tensile strength and residual elongation at break were evaluated. The test was qualified if the residual tensile strength and residual elongation at break were both 60% or more.

[0109] (4) Maximum static friction coefficient

[0110] For the prepared cables, the maximum static friction coefficient was obtained by the tilt method. Figure 2 This is a diagram showing the method of determining the maximum static friction coefficient. Figure 2 As shown in the stereogram of (a), two cables are fixed on a rectangular plate in parallel with a predetermined direction (e.g., the direction in which the long side of the plate extends). The outer diameter of the cable is 29 mm, the weight is 650 g, and the length is 50 cm. A sheath material 3 is arranged on the outer periphery of the cable. Two sets of such plates are prepared. Next, Figure 2 As shown in the cross section of (b), the plates (PL1, PL2) with cables (sheath materials) fixed thereto are stacked so that the cables are in contact with each other in a vertical state. After fixing the first end of the plate PL1 located at the lower side, the second end is raised so that the plate PL1 gradually tilts from the horizontal, and the angle θ at which the plate PL2 located at the upper side starts to slide is measured. The tanθ value is taken as the maximum static friction coefficient between the cables (sheath materials), and a value less than 1.0 is considered acceptable.

[0111] (5) Comprehensive judgment

[0112] Those who meet all of the above (1) to (4) are considered qualified.

[0113] The above evaluation results are shown in Table 2.

[0114] Table 2

[0115]

[0116] In the present embodiment, for Examples 1 to 6 shown in Table 1, the maximum static friction coefficient between the cables is insufficient, and it can be confirmed that the cable wrinkling can be suppressed. In particular, in the rubber-coated cable as the cable for the movable part, the rubber-coated cable can suppress the cable wrinkling even when it contacts with a metal material such as a reel, which has a higher possibility of contact, compared with the contact between the rubber-coated cables.

[0117] In addition, the frictional resistance of the cable changes according to the weight of the cable, the objects it contacts, etc., so it is difficult to find the best material, but the maximum static friction coefficient between the cables is used as a reference, which is easy to judge the frictional resistance of the cable and can be widely used. In addition, according to the above-mentioned inclination method, the maximum static friction coefficient can be easily obtained.

[0118] Furthermore, for Examples 1 to 6, the rubber hardness measured by the A-type durometer was less than 85, which confirmed that the cable was easy to bend. In particular, in the rubber-coated cable as a cable for a movable part, since the cable is easy to bend, the force to move the cable can be reduced, and the motor load when winding the cable can be reduced.

[0119] The above-mentioned Examples 1 to 6 have better maximum static friction coefficient and hardness than Comparative Examples 1 to 4, and also have better properties such as oil resistance, tensile strength, and elongation at break. In Examples 1 to 6, the weight ratio of chlorinated rubber to ethylene copolymer is 40:60 to 80:20. Using the base polymer in such a mixing ratio, a sheath material with good properties can be obtained.

[0120] It should be noted that in the above embodiments and examples, the cross-sectional shape of the cable is a perfect circle or a substantially perfect circle (refer to Figure 1 ) is used as an example to explain the sheath material, but the cross-sectional shape of the cable is not limited to the above. For example, the above sheath material can also be applied to the coating layer of a flat cable.

[0121] Thus, the friction coefficient of the cable with different shapes can be measured by using a simulated cable with the sheath material stripped off. For example, a simulated cable with a cylindrical shape substantially the same as the cable described in (4) above is used, and the sheath material is stripped off from the flat cable on the entire or a part of the outer circumference thereof and fixed to the simulated cable. For example, the friction coefficient is measured by using a cable adjusted to an outer diameter of 29 mm, a weight of 650 g, and a length of 50 cm.

[0122] Therefore, the present invention is not limited to the above-described embodiment and examples, and various modifications can be made without departing from the spirit and scope of the present invention.

[0123] Next, one aspect of the present invention based on the above-described embodiment is added.

[0124] Appendix 1: An elastomeric resin composition, comprising a mixture of a chlorinated rubber and an ethylene copolymer; the chlorinated rubber is selected from at least one of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene, and the ethylene copolymer is selected from at least one of ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, modified products of these copolymers, and terpolymers of two monomers constituting these copolymers and other monomers; wherein the weight ratio of the chlorinated rubber to the ethylene copolymer is 40:60 to 80:20.

[0125] Appendix 2: According to the elastomer resin composition described in Appendix 1, the chlorine-based rubber is chlorinated polyethylene, and the ethylene-based copolymer is ethylene-vinyl acetate copolymer.

[0126] Appendix 3: The elastomer resin composition according to Appendix 1, wherein the maximum static friction coefficient between crosslinked products of the elastomer resin composition is less than 1.0, and the rubber hardness measured by a type A durometer is less than 85.

Claims

1. A rubber-coated cable comprising a core and a coating layer provided on the core, wherein the core is formed by twisting a plurality of electric wires having an insulating layer coated on a conductor, The coating layer is formed of a cross-linked product of an elastomer resin composition, The elastomer resin composition comprises a mixture of chlorine-based rubber and ethylene-based copolymer, and further contains carbon black and a plasticizer as a reinforcing agent. The chlorinated rubber is selected from at least one of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. The ethylene-based copolymer is at least one selected from ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, modified products of these copolymers, and terpolymers of two monomers constituting these copolymers and other monomers, For the coating layer, the maximum static friction coefficient between the coating layers obtained by the tilt method is less than 1.0, and the hardness measured by the A-type durometer is less than 85, The weight ratio of the chlorine-based rubber to the ethylene-based copolymer is 70:30 to 80:

20.

2. The rubber-coated cable according to claim 1, wherein the chlorine-based rubber is chlorinated polyethylene, and the ethylene-based copolymer is ethylene-vinyl acetate copolymer. 3 . The rubber-coated cable according to claim 1 , wherein the core is formed by twisting a plurality of electric wires coated with the insulating layer on the conductor and winding a single-sided rubber release cloth tape thereon. 4 . The rubber-coated cable according to claim 3 , wherein the rubber release surface of the single-sided rubber release cloth tape is located on the coating layer side.

5. The rubber-coated cable according to claim 1, wherein the maximum static friction coefficient between the coating layers obtained by the tilt method is obtained by the following method 1: Method 1: Prepare two rubber-coated cables, fix the two rubber-coated cables on a rectangular plate in parallel to a predetermined direction, and prepare two sets of plates on which the rubber-coated cables are fixed; the outer diameter of the rubber-coated cable is 29 mm, the weight is 650 g, and the length is 50 cm; The two sets of plates fixing the rubber-coated cables are overlapped so that the rubber-coated cables are in vertical contact with each other; after fixing the first end of the plate arranged on the lower side, the second end of the plate arranged on the lower side is raised so that the plate arranged on the lower side gradually tilts from the horizontal, and the angle θ at which the plate arranged on the upper side starts to slide is measured, and the tanθ value is used as the maximum static friction coefficient between the coating layers.

6. A method for manufacturing a rubber-coated cable, comprising: The process of forming a core by twisting a plurality of electric wires covered with an insulating layer on the conductor. A process of forming a coating layer on the core by extrusion, A step of forming lead on the outer periphery of the coating layer and cross-linking the coating layer; In the manufacturing method of the rubber-coated cable, The coating layer is formed of a cross-linked product of an elastomer resin composition, The elastomer resin composition comprises a mixture of chlorine-based rubber and ethylene-based copolymer, and further contains carbon black and a plasticizer as a reinforcing agent. The chlorinated rubber is selected from at least one of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. The ethylene-based copolymer is at least one selected from ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, modified products of these copolymers, and terpolymers of two monomers constituting these copolymers and other monomers, For the coating layer, the maximum static friction coefficient between the coating layers obtained by the tilt method is lower than 1.0, the hardness measured by a type A durometer is lower than 85, and the weight ratio of the chlorine-based rubber to the ethylene-based copolymer is 70:30 to 80:

20.

7. The method for manufacturing a rubber-coated cable according to claim 6, wherein in the step of manufacturing the core, a plurality of electric wires on which the insulating layer is coated on the conductor are twisted together, and a single-sided rubber release cloth tape is wound thereon to manufacture the core.

8. The method for manufacturing a rubber-coated cable according to claim 7, wherein in the process of manufacturing the core, a plurality of electric wires coated with the insulating layer on the conductor are twisted together, and the single-sided rubber release cloth tape is wound thereon so that its rubber release surface is on the coating layer side, thereby manufacturing the core.

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