JP6975378B2 - Sheath material and cable - Google Patents

Description

The present invention relates to a sheath material and a cable.

The cable includes an insulated wire and a sheath layer provided on the outer periphery of the insulated wire. The insulated wire has a conductor and an insulating layer provided on the outer periphery of the conductor, and the sheath layer is provided on the outer periphery of the insulating layer. As described above, the sheath layer is arranged on the outermost periphery of the cable and is made of an electrically insulating material mainly made of rubber or resin.

For example, Patent Document 1 describes a resin composition for coating an insulated electric wire, which comprises 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 which is solid at room temperature. Is disclosed.

Further, in Patent Document 2, by adding a silicone powder to the flame-retardant resin composition of at least one of the insulating layer or the sheath layer on the outer periphery of the conductor of the flat cable, the slipperiness between the insulating layer and the sheath layer or the insulating layer is described. The technology to improve is disclosed.

Further, Patent Document 3 describes in a multi-core cable configured by twisting an insulating core wire having an insulating core coated with a thermoplastic resin as an insulator on the outer periphery of a conductor, the thermoplastic resin being made of a polyester elastomer and having an organic high molecular weight. A technique for providing a bending / twist resistant cable by containing 0.5 to 3.0% by mass of a silicone polymer is disclosed.

Japanese Unexamined Patent Publication No. 2001-31903 Japanese Unexamined Patent Publication No. 2003-7144 Japanese Unexamined Patent Publication No. 2008-218061

As described above, since the sheath layer of the cable is a layer arranged on the outermost circumference of the cable, for example, when the frictional resistance is large such as a rubber sheath layer, (1) contact between cables, (2) Wiring becomes difficult due to contact between the cable and other articles. In particular, in a cabtire cable that is a cable for moving parts that is used while being moved together with connecting devices, if the frictional resistance of the sheath layer is large, (1) contact between the cables, (2) the cable and other articles The contact may cause the cable to swell, causing the conductor inside the insulated wire inside the cable to kink and buckle, causing the conductor inside the insulated wire to break.

On the other hand, for the purpose of reducing the frictional resistance of the sheath layer, the technology of adding silicone powder and the technology of blending silicone polymer are being studied as described above, but the frictional resistance may become extremely large with the usage time of the cable. , It was not enough from the viewpoint of maintaining the slipperiness.

Although it is conceivable to use a polymer having excellent slidability typified by fluororesin, fluororesin is not suitable for application to cables that are required to be flexible.

It is an object of the present invention to provide a sheath material or cable having flexibility while maintaining slipperiness.

[1] The sheath material according to one aspect of the present invention comprises an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, and a copolymer of these and another monomer. It is composed of a crosslinked product consisting of an elastomer resin composition containing a mixture of at least one type of ethylene-based copolymer selected from the ternary copolymer and chlorinated polyethylene as a base polymer, and is maximally stationary between the crosslinked products. A sheath material having a friction coefficient of less than 1.0 and a hardness of less than 85 as measured by an A-type polymer.
[2] In the sheath material according to [1], the chlorine content of the chlorinated polyethylene is 25% by mass or more and 40% by mass or less.
[3] In the sheath material according to [1] or [2], the sheath material has a mass ratio of the chlorinated polyethylene to the ethylene-based copolymer of 50:50 to 90:10.
[4] In the sheath material according to [3], the ethylene-based copolymer is a sheath material which is an ethylene-vinyl acetate copolymer.
[5] A conductor, an insulating layer provided around the conductor, and a sheath layer provided around the insulating layer are provided, and the sheath layer is a polyethylene-α-olefin copolymer or ethylene-vinyl acetate. At least one type of ethylene-based copolymer selected from polymers, ethylene-acrylic acid ester copolymers, and ternary copolymers of these copolymers and other monomers, and chlorinated polyethylene. A cable comprising a crosslinked product consisting of an elastomeric resin composition containing the mixture as a base polymer, having a maximum static friction coefficient of less than 1.0 between the crosslinked products and a hardness of less than 85 as measured by an A-type durometer. be.
[6] In the cable according to [5], the chlorine content of the chlorinated polyethylene is 25% by mass or more and 40% by mass or less.
[7] In the cable according to [5] or [6], the mass ratio of the chlorinated polyethylene to the ethylene-based copolymer is 50:50 to 90:10. [8] In the cable according to [7], the ethylene-based copolymer is a cable which is an ethylene-vinyl acetate copolymer.

"Waviness" is a state in which the sheath layer is twisted due to frictional resistance caused by contact between cables or contact between cables and other articles, and the cable core composed of twisted insulated wires is loosened and the arrangement is disturbed. It means that it becomes. When the insulated wire is operated in a disordered state in this way, the insulated wire is forcibly bent, and the conductor inside the insulated wire is kinked and buckled. Therefore, we thought that if the frictional resistance of the cable was small, we could suppress the "waviness", and as a result of examining the maximum value of the frictional resistance of the cable surface that suppresses the "waviness" of the cable, the maximum static friction coefficient between the sheath layers was 1.0. It was found that if it is less than, the "waviness" of the cable can be suppressed.

Further, even if the maximum coefficient of static friction between the sheath layers is less than 1.0, if the sheath layer is hard, the cable is difficult to bend and the cable wiring work becomes difficult. Therefore, a flexible cable was realized by setting the hardness measured by the A type durometer of the sheath layer to less than 85.

Although chlorinated polyethylene can satisfy the bendability required for cables, it cannot achieve a maximum static friction coefficient of less than 1.0 between sheath layers by chlorinated polyethylene alone because of its high frictional resistance. Therefore, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, and copolymers thereof having crystals at 25 ° C to 60 ° C, which is the assumed temperature range for cables, and their copolymers. By using a mixture of at least one ethylene-based copolymer selected from a ternary copolymer of a polymer and another monomer and chlorinated polyethylene, the sheath is used without significantly reducing the bendability. It was found that the maximum static friction coefficient between the layers can be lowered and the slipperiness can be maintained.

According to the present invention, it is possible to provide a sheath material or a cable having flexibility while maintaining slipperiness.

It is a figure which shows the cable of one Embodiment of this invention. It is a figure which shows the measuring method of the maximum static friction coefficient.

(Embodiment)
<Elastomer resin composition>
The elastomer resin composition of the present embodiment contains, as a base polymer, an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, and these copolymers and other monomers. It contains a mixture of at least one kind of ethylene-based copolymer selected from the ternary copolymers of the above and chlorinated polyethylene. This is because by using such a mixture, the maximum coefficient of static friction between the crosslinked products can be reduced without significantly reducing the flexibility. Further, as the chlorinated polyethylene or the ethylene-based copolymer, the following materials can be used.

(Chlorinated polyethylene)
Chlorinated polyethylene can be obtained, for example, by suspending powdered linear polyethylene (from high density to low density) as an aqueous suspension and blowing chlorine gas into the system at a temperature near the crystal melting point of the raw material polyethylene. Since the chlorinated polyethylene is obtained by a heterogeneous reaction, the crystallinity can be controlled from an amorphous rubber-like one to a semi-crystalline or crystalline plastic-like monomer. Chlorinated polyethylene is a thermoplastic elastomer with a wide range of properties. By using chlorinated polyethylene, the flexibility required for the cable can be satisfied.

Further, by using chlorinated polyethylene, oil resistance can be improved. As a result, deterioration of the cable due to oil such as machine oil can be suppressed.

The chlorine content of the chlorinated polyethylene is preferably 40% by mass or less. The chlorine content is the mass% concentration of chlorine in chlorinated polyethylene. Further, the chlorinated polyethylene preferably has no crystals.

On the other hand, if the chlorine content exceeds 40% by mass, the properties are similar to those of polyvinyl chloride, and the chlorine content becomes too hard. In addition, the compatibility with the ethylene-based copolymer, which will be described later, is reduced. Therefore, the tensile strength may decrease. On the other hand, the chlorine content of the chlorinated polyethylene is preferably 25% by mass or more and 40% by mass or less. When the chlorine content is less than 25% by mass, the oil resistance tends to decrease. More preferably, the chlorine content of the chlorinated polyethylene is 30% by mass or more and 40% by mass or less, and 35% by mass or more and 40% by mass or less.

(Ethylene copolymer)
As the ethylene-based copolymer, an ethylene-vinyl acetate copolymer, an ethylene-α-olefin copolymer, an ethylene-acrylic acid ester copolymer, or the like is preferably used. These have crystals in a temperature range of about 25 ° C. or higher and 60 ° C. or lower. By using a mixture of these ethylene-based copolymers and chlorinated polyethylene, the maximum coefficient of static friction between the crosslinked products can be set to less than 1.0 without significantly reducing the bendability.

Ethylene-vinyl acetate copolymer (EVA) is a copolymer of ethylene and vinyl acetate.

The ethylene-α-olefin copolymer is a copolymer of ethylene and α-olefin.

The ethylene-acrylic acid ester copolymer is a copolymer of ethylene and acrylic acid ester. Examples of the acrylic acid ester include those obtained by esterifying acrylic acid and alcohol, and examples of the ethylene-acrylic acid ester copolymer include an ethylene-methyl acrylate copolymer (EMA) and an ethylene-ethyl acrylate copolymer (EEA). ), Ethylene-butyl acrylate copolymer (EBA) and the like can be used. Further, it may be manufactured by a different method such as a graft polymer.

Further, the ethylene-vinyl acetate copolymer, the ethylene-α-olefin copolymer, and the ethylene-acrylic acid ester copolymer may be modified products. For example, it may be modified with a polar functional group. Examples of the polar functional group include an epoxy group, a carboxyl group, and a maleic anhydride group. For example, an ethylene-α-olefin copolymer modified with maleic anhydride can be used.

In addition, using ternary copolymerization of two types of monomers constituting the copolymers of ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer and ethylene-acrylic acid ester copolymer, and other monomers. It is also good. For example, a ternary copolymer of ethylene, acrylic acid ester and other monomers may be used. Examples of such a ternary copolymer include ethylene-maleic anhydride-methyl acrylate copolymer, ethylene-maleic anhydride-ethyl acrylate copolymer and the like.

As described above, by using a mixture of chlorinated polyethylene and the above ethylene-based copolymer as the base polymer, the maximum coefficient of static friction between the crosslinked products can be lowered without significantly reducing the bendability. In this case, in order to reduce the frictional resistance of the base polymer itself, the frictional resistance does not become extremely large with the usage time of the cable, as in the case of imparting slipperiness by adding silicone powder, etc., and the slipperiness is maintained. It can be and is useful.

Then, as shown in Examples described later, the characteristics are excellent when the mass ratio of the chlorinated polyethylene and the ethylene-based copolymer is 50:50 to 90:10. More preferably, it is 70:30 to 90:10. This is because when the mixing ratio of the ethylene-based copolymer is less than 10, the maximum coefficient of static friction becomes large, and when the mixing ratio of the ethylene-based copolymer exceeds 50, it becomes too hard.

Further, when an ethylene-vinyl acetate copolymer is used as the ethylene-based copolymer, it has a slight polarity and the compatibility with chlorinated polyethylene is increased. As described above, in the present embodiment, the compatibility is better than that in the case of blending, for example, an organic high molecular weight silicone polymer, and as a result, mechanical properties such as tensile strength can be improved.

Further, the softness of the ethylene-vinyl acetate copolymer can be adjusted by adjusting the vinyl acetate content. In particular, the vinyl acetate content of the ethylene-vinyl acetate copolymer is preferably 25 to 35% by mass. If the vinyl acetate content is less than 25% by mass, it is slightly hard, and if it exceeds 35% by mass, it approaches rubber-like properties, so that the frictional resistance tends to increase. The vinyl acetate content is the mass% concentration of vinyl acetate in the ethylene-vinyl acetate copolymer.

Various additives can be added to the base polymer as needed. The additives will be described below.

(Crosslinking agent)
In order to improve the heat resistance and oil resistance of the base polymer and also to improve the mechanical properties such as tensile strength, the base polymer is made by adding sulfur compounds and organic peroxides, electron beam irradiation, silane graft water cross-linking, etc. Cross-linking is preferred. A silanol condensation catalyst masterbatch supplemented with a silanol condensation catalyst can also be used . The cross-linking agent, for example, 1,3-bis (2-t-butylperoxy isopropyl) benzene, can be used organic peroxides such as dicumyl peroxide (DCP). In addition, cross-linking aids such as polyfunctional monomers such as triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and trimethylolpropane trimethacrylate (TMPT) may be used in combination to increase the degree of cross-linking. Further, as the cross-linking aid, for example, a sulfur compound such as ethylene thiourea, dibenzothiazyl disulfide, or trimethylthiourea may be used.

(Stabilizer)
Stabilizers may be used to prevent deterioration of the base polymer. Examples of the stabilizer include lead-based stabilizers such as tribasic lead sulfate, tin compounds, epoxy-based stabilizers, hydrotalcites, and Ca / Zn-based stabilizers.

In particular, in the present embodiment, it is preferable to add a stabilizer that traps hydrogen chloride to the base polymer because it contains chlorinated polyethylene. As such a stabilizer, a hydrotalcite-like compound, epoxidized soybean oil, or the like can be used. By adding such a stabilizer, hydrogen chloride generated when the temperature becomes high during processing or use can be captured.

(Reinforcing material)
Reinforcing agents may be used to improve mechanical properties such as tensile strength of the base polymer. Carbon black can be used as the reinforcing agent.

(Antioxidant)
In order to suppress the oxidation of the polymer, an amine-based antioxidant may be used. As the amine-based antioxidant, for example, a diphenylamine-based compound, a quinoline-based compound, or the like may be used. Examples of the diphenylamine compound include a diphenylamine derivative (manufactured by Kawaguchi Chemical Industry Co., Ltd., Antage DDA (trade name)). Examples of the quinoline compound include 2,2,4-trimethyl1,2-dihydroquinoline polymer (trade name: Nocrack 224; JIS abbreviation TMDQ). These amine-based antioxidants can be used alone or in a blend of two or more. In particular, diphenylamine-based compounds and quinoline-based compounds are suitable for radical capture.

(Other additives)
Other additives include flame retardants, lubricants, surfactants, softeners, plasticizers, inorganic fillers, compatibilizers, metal chelating agents (copper damage inhibitors), UV absorbers, light stabilizers, colorants, etc. May be used.

<Sheath material>
The sheath material of the present embodiment means a crosslinked product of the above elastomer resin composition. The elastomer resin composition becomes a sheath material by being crosslinked. There is a method of performing the cross-linking process by applying energy such as heat or electron beam after covering the cable, but all of them require large-scale equipment and a large amount of energy. On the other hand, the silane cross-linking method is a large-scale facility because the cross-linking is promoted by the action of water after the sheath layer is formed by chemically binding the silane coupling agent to the polymer molecule which is the sheath layer in advance. It is possible to manufacture cables with excellent environmental and economic efficiency without requiring a large amount of energy.

It may be heated to promote the cross-linking reaction, and for the specific cross-linking method, the location and conditions (humidity, temperature, time, etc.) such as storage in a steam room, indoors and outdoors of a building, or a constant temperature room are used. It doesn't matter.

The sheath material of the present embodiment has a maximum coefficient of static friction between crosslinked products of less than 1.0. It was found that if the maximum coefficient of static friction between the crosslinked objects is less than 1.0, the swell of the cable can be suppressed not only by the contact between the cables but also by the contact with a metal material such as a reel that the cable is likely to contact. Is. More preferably, the maximum coefficient of static friction between the crosslinked products is 0.4 or more and 0.9 or less, 0.4 or more and 0.7 or less, and 0.4 or more and 0.6 or less.

The sheath material of the present embodiment has a hardness of less than 85 as measured by an A type durometer. More preferably, the hardness measured by the A type durometer is 74 or more and 83 or less, and 74 or more and 80 or less. This is to realize a cable that is easier to bend.

For example, the elastomer resin composition is kneaded, and the elastomer resin composition is extruded and covered around a cable core made of an insulated wire using an extruder or the like, and then crosslinked to be applied to the outer periphery of the cable core. Form a sheath material. A regular device can be used for kneading and extrusion.

<Cable configuration>
FIG. 1 is a diagram showing a cable of the present embodiment. FIG. 1 is a cross-sectional view of a cable.

As shown in FIG. 1, the cable of the present embodiment has a cable core in which a plurality of (four in FIG. 1) insulated wires 2 are twisted, and a sheath layer 3 is formed on the outer periphery thereof. The insulated wire 2 has a conductor 21 and an insulating layer 22 that covers the conductor 21. An interposition (not shown) or the like may be provided on the outer periphery of the cable core, and the sheath layer 3 may be provided on the outer periphery thereof.

The conductor 21 is formed of, for example, a conductive material such as copper or a copper alloy (eg, tin-plated annealed copper wire) and has a predetermined conductor cross-sectional area. The conductor diameter of the conductor 21 is not particularly limited, and an optimum value is appropriately selected according to the intended use.

As the material of the insulating layer 22, a material generally used for a cable can be used. As the insulating layer 22, for example, an ethylene-propylene rubber admixture can be used. Further, a fluororesin (for example, ethylene-tetrafluoroethylene copolymer (ETFE) or the like) may be used as the insulating layer 22. Fluororesin has excellent mechanical properties such as tensile strength and slidability, and can be reduced in thickness. This makes it possible to reduce the diameter of the cable.

The sheath layer 3 is made of the above-mentioned elastomer resin composition. Specifically, it is composed of a sheath material which is a crosslinked product of the above-mentioned elastomer resin composition.

The cable of the present embodiment is suitable for a cable for moving parts, and can be used for a cabtire cable, a cable for a robot, a medical cable, and various flexible cables.

<Cable manufacturing method>
Next, a method for manufacturing the cable according to the present embodiment will be described.

First, a plurality of insulated wires 2 in which the conductor 21 is covered with the insulating layer 22 are prepared. A plurality of prepared insulated wires 2 are twisted together to form a cable core. Next, the elastomer resin composition is extruded and coated around the cable core using an extrusion molding machine or the like.

Next, the elastomer resin composition covering the cable core is subjected to a cross-linking treatment (for example, treatment with high-pressure steam at a predetermined temperature) to cross-link the elastomer resin composition to form a sheath layer 3 on the outer periphery of the cable core. As a result, the cable of the present embodiment is obtained. Here, a cable having a plurality of insulated wires 2 has been described, but a cable having one insulated wire 2 can also be covered with the sheath layer 3 in the same manner.

Here, the insulator (crosslinked product of the elastomer resin composition) constituting the sheath layer 3 has a maximum static friction coefficient of less than 1.0 between the crosslinked products. Further, the crosslinked product constituting the sheath layer 3 has a hardness of less than 85 as measured by an A type durometer.

As described above, according to the present embodiment, as the base polymer, a crosslinked product made of an elastomer resin composition having a mixture of chlorinated polyethylene and an ethylene-based copolymer in a predetermined mass ratio is formed in the sheath layer of the cable. Since it is used, the slipperiness and bendability of the cable can be improved. Specifically, the maximum coefficient of static friction between crosslinked objects can be set to less than 1.0, and the slipperiness of the cable can be improved. As a result, resistance at the time of (1) contact between cables and (2) contact between the cable and other articles is reduced, and cable wiring becomes easy. Further, the hardness measured by the A type durometer of the sheath layer of the cable can be set to less than 85, and as a result, the cable can be easily bent and the wiring of the cable becomes easy.

In particular, since the sheath material made of the elastomer resin composition of the present embodiment has flexibility while maintaining slipperiness, it is a cabtire cable which is a cable for moving parts used while being moved together with a connecting device. Even when it is used as a sheath layer, it is possible to suppress the undulation of the cable that occurs when the cable is used repeatedly. When the insulated wire is operated in a disordered state in this way, the insulated wire is bent unreasonably, and the conductor inside the insulated wire is kinked and buckled. According to the sheath material made of the elastomer resin composition of the present embodiment, by suppressing the swell, the kink and buckling of the conductor inside the insulated wire inside the cable are suppressed, and the disconnection of the conductor inside the insulated wire is avoided. It is possible to improve the characteristics of the cable.

Hereinafter, the elastomer resin composition of the present embodiment and the cable using the elastomer resin composition will be described in more detail with reference to Examples. The present invention is not subject to any restrictions according to the following examples.

The elastomeric resin compositions of each example were prepared under the following methods and conditions.

[Elastomer resin composition]
(Silane graft pretreatment)
The mixture of chlorinated polyethylene and the ethylene-based copolymer used for the graft treatment was pretreated as follows. A powdered chlorinated polyethylene was kneaded using an 8-inch roll machine, and a stabilizer, a lubricant, and a peroxide were added thereto. As the kneading conditions, the roll surface temperature was 100 ° C., and all the additives were kneaded into the chlorinated polyethylene and then kneaded for 5 minutes. After kneading the additive, a sheet was prepared and pelletized into a shape of about 5 mm square.

(Silane graft treatment)
The graft treatment was carried out by using a single-screw extruder (L / D = 25) having a screw diameter of 40 mm. The screw had a full flight shape and a compression ratio of 2.0, and the die was extruded into a strand shape using a strand extrusion die (hole diameter φ5 mm, number of holes 3). The set temperature was set to cylinder 1: 80 ° C., cylinder 2: 200 ° C., head: 200 ° C. in order from the hopper side, and the screw rotation speed was set to 20 rpm (extrusion amount about 120 g / min). Silane graft pretreated pellets of a mixture of chlorinated polyethylene and an ethylene-based copolymer were sufficiently impregnated with silane in a plastic bag. The pellet was extruded by supplying it from the extruder hopper. Strands of a mixture of extruded silane graft chlorinated polyethylene and an ethylene-based copolymer were water-cooled by passing through a water tank having a length of 150 cm and then pelletized.

(Addition of filler to the mixture of silane graft chlorinated polyethylene and ethylene-based copolymer)
A plasticizer, an antioxidant, carbon black, and a lubricant were added to the mixture of the silane graft chlorinated polyethylene and the ethylene-based copolymer using an 8-inch roll machine, and the mixture was kneaded. As for the kneading conditions, the roll surface temperature was 100 ° C., and after all the additives were added, kneading was performed for 5 minutes. The kneaded sheet was pelletized into a shape of about 5 mm square.

(Preparation of silanol condensation catalyst masterbatch)
A mixture of chlorinated polyethylene and an ethylene-based copolymer and a silanol condensation catalyst were kneaded using an 8-inch roll machine at a roll surface temperature of 100 ° C. First, chlorinated polyethylene was kneaded into a roll, then a catalyst was added, and then kneading was performed for 3 minutes. The kneaded sheet was pelletized into a shape of about 5 mm square.

[Cable manufacturing and cross-linking]
Insulation made by extruding and coating a mixture of ethylene-propylene rubber copolymer with a thickness of 0.5 mm on a conductor with a conductor cross-sectional area of 0.3 mm ^{2 and an outer diameter of 0.7 mm, which is made by twisting multiple tin-plated annealed copper wires.} A cable core made by twisting four electric wires, and a dry blend of pellets of a mixture of silane graft chlorinated polyethylene with a filler and an ethylene-based copolymer and pellets of a silanol condensation catalyst masterbatch with a screw diameter of 20 mm. A cable having a finished outer diameter of about 6.8 mm was produced by extrusion-coating to a thickness of 1.2 mm using a shaft extruder (L / D = 25). The set temperature is from the hopper side to cylinder 1: 120 ° C, cylinder 2: 130 ° C, head: 130 ° C, neck: 130 ° C, die: 130 ° C, screw rotation speed 20 rpm, screw full flight shape, compression ratio 2 The one of .0 was used. The manufactured cable was crosslinked by storing it in a constant temperature and humidity chamber having a temperature of 50 ° C. and a relative humidity of 95% for 24 hours.

In the above embodiment, a roll machine or an extruder was used to achieve the kneading / grafting reaction, but other than this, the kneading and reaction equipment generally used such as a kneader, a mixer, and an autoclave are particularly limited. However, these kneading and graft reaction conditions (temperature, time) are not limited to the above range. Similarly, in the manufacture of the above cable, the extruder, cable core, and cross-linking conditions are not limited in any way.

Further, when the sheet after kneading is pelletized, a pellet adhesion inhibitor may be sprinkled, and when the pellet of the mixture is impregnated with silane, talc or the like may be sprinkled to prevent mutual adhesion of the pellets. .. Further, the kneading conditions for the silane graft pretreatment are not particularly limited, and should be set in consideration of sufficient dispersion of the additive in the chlorinated polyethylene without thermally decomposing the peroxide. It's fine.

The silanol condensation catalyst includes group II such as magnesium and calcium, group VIII such as cobalt and iron, elements and metal compounds such as tin, zinc and titanium, metal salts of octylic acid or adipic acid, and amine compounds. Examples include acid. More specifically, dioctyltin dineodecanoate, dibutyltin dilaurirate, dibutyltin diacetate, dibutyltin dioctaate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, cobalt naphthenate, Inorganic acids such as ethylamine, dibutylamine, hexylamine, pyridine, sulfuric acid and hydrochloric acid, and organic acids such as toluenesulfonic acid, acetic acid, stearic acid and maleic acid are used.

(evaluation)
Cables were evaluated according to the tests and criteria shown below.
(1) Tensile test The manufactured cable was subjected to a tensile test in accordance with IEC60811-1-1. A tensile strength of 10 MPa or more was accepted so as to conform to SE4 specified in IEC60254-1 issued by the International Electrotechnical Commission. In addition, those with a breaking elongation of 300% or more were regarded as acceptable.
(2) Durometer A hardness (hardness measured by A type durometer) test The sheath layer was peeled off from the cable, and the unevenness of the surface was smoothed by polishing. Three or less sheath layers were laminated so that the total thickness was 6 mm or more, and used as a sample. This sample was measured using an A type durometer (rubber hardness tester) based on JIS K 6253. A durometer A hardness of less than 85 was regarded as acceptable.
(3) Oil resistance The manufactured cable was subjected to an oil resistance test in accordance with IEC60811-2-1. IRM902 oil is used as the immersion oil so as to comply with SE4 specified in IEC60254-1 issued by the International Electrotechnical Commission, and after immersion at an oil temperature of 100 ° C. and an immersion time of 24 hours, the tensile strength The residual ratio and the tensile elongation residual ratio were evaluated. Those with a tensile strength residual ratio and a tensile elongation residual ratio of 60% or more were regarded as acceptable.
(4) Maximum static friction coefficient The maximum static friction coefficient was obtained for the manufactured cable by the tilting method. FIG. 2 is a diagram showing a method of measuring the maximum static friction coefficient. As shown in the perspective view of FIG. 2A, two cables are fixed to the rectangular plate in parallel in a predetermined direction (for example, the extending direction of the long side of the plate). The outer diameter of the cable is 29 mm, its own weight is 650 g, and its length is 50 cm. A sheath material 3 is arranged on the outer periphery of the cable. Prepare two sets of such boards. Next, as shown in the cross-sectional view of FIG. 2B, the plates (PL1 and PL2) to which the cables (sheath material) are fixed are superposed so that the cables are in contact with each other in an orthogonal state. Then, after fixing the first end of the plate PL1 installed on the lower side, the second end is lifted so that the plate PL1 gradually inclines from the horizontal, and the angle θ at which the plate PL2 installed on the upper side starts to slide is measured. do. The value of tan θ was taken as the maximum coefficient of static friction between cables (between crosslinked objects), and less than 1.0 was regarded as acceptable.
(5) Comprehensive judgment Those satisfying all of the above (1) to (4) were regarded as acceptable.

In Tables 1 to 3, ML indicates the Mooney viscosity (minimum value) 4 minutes after preheating at 121 ° C., and MFR indicates the melt mass flow rate at 190 ° C. under a 2.16 kg load.

The evaluation results are shown in Tables 1 to 3.

In this example, in Examples 1 to 8 shown in Tables 1 and 2, the maximum static friction coefficient between the cables is less than 1.0, and it can be confirmed that the swell of the cables can be suppressed. In particular, in a cabtire cable which is a cable for moving parts, swelling of the cable can be suppressed not only when the cabtire cable comes into contact with the cable but also when the cabtire cable comes into contact with a metal material such as a reel which is likely to come into contact with the cabtire cable.

In addition, it was difficult to find the optimum material because the frictional resistance of the cable changes depending on the weight of the cable and the articles that come into contact with it. The frictional resistance can be easily and universally determined. Further, with the inclination method described above, the maximum coefficient of static friction can be easily obtained.

Further, in Examples 1 to 8, the hardness measured by the A type durometer is less than 85, and it can be confirmed that the cable is easily bent. In particular, in the case of a cable for moving parts that is used while moving together with connected devices, the easy bending of the cable can reduce the force for moving the cable and reduce the load on the motor such as winding the cable. ..

In Examples 1 to 7, the maximum static friction coefficient and the durometer A hardness can be obtained better than those in Comparative Examples 1 to 7, and the characteristics such as oil resistance, tensile strength, and elongation at break are also good. Met. In Examples 1 to 8, the mass ratio of the chlorinated polyethylene to the ethylene-based copolymer is 50:50 to 90:10, and by using a base polymer having such a mixing ratio, the characteristics are good. The sheath material could be obtained. Among them, Examples 1 to 7 have a higher residual tensile strength after oil immersion than Example 8, and Examples 1 to 7 are superior to Example 8 in terms of oil resistance. You can see that.

It is presumed that there are two factors that cause such a difference in oil resistance. One of the factors seems to be the chlorine content of chlorinated polyethylene. When the chlorine content of chlorinated polyethylene is low, the polarity of the polymer decreases, so it is considered that the affinity with oil increases and the tensile strength after immersion in oil decreases. On the other hand, when the chlorine content is high, the aggregation energy between chlorine atoms increases, so that the rigidity of the polymer increases, the elongation at break (dextability) decreases, and the hardness is considered to have increased excessively, and chlorinated polyethylene and ethylene. -It is considered that the difference in polymer polarity of the vinyl acetate copolymer became large and the compatibility between the polymers decreased, so that the ductility decreased.

The second factor is the mixing ratio of chlorinated polyethylene. When the mixing ratio of chlorinated polyethylene increases, the properties as rubber become remarkable and the slipperiness decreases, and conversely, when the mixing ratio of ethylene-vinyl acetate copolymer increases, the amount of crystals in the mixed polymer increases and thus ductility. It is considered that the amount of chlorine in the mixed polymer is reduced and the oil resistance is also lowered, in addition to the decrease in hardness and the increase in hardness.

In Comparative Example 1, since the chlorine content of the chlorinated polyethylene was high, the durometer A hardness was 85, which was unacceptable.

In Comparative Example 2, since the amount of the ethylene-vinyl acetate copolymer added was small, the maximum static friction coefficient was 1.2, which was unacceptable.

In Comparative Example 3, since the amount of the ethylene-vinyl acetate copolymer added was large, the durometer A hardness was 86, which was unacceptable.

In the above-described embodiments and examples, a sheath layer having a cable cross-sectional shape of a perfect circle or a substantially perfect circle (see FIG. 1) has been described as an example, but the cross-sectional shape of the cable is limited to the above. It's not something. For example, the sheath material may be applied to a flat cable.

As described above, the coefficient of friction when the shape of the cable is different can be measured by using a pseudo cable to which the stripped sheath material is attached. For example, using a columnar pseudo-cable similar to the cable described in (4) above, the sheath layer of the flat cable is stripped off all or part of the outer circumference thereof and fixed to the pseudo-cable, for example, outside. The coefficient of friction can be measured using a cable adjusted to have a diameter of 29 mm, a weight of 650 g, and a length of 50 cm.

As described above, the present invention is not limited to the above embodiments and examples, and can be variously modified without departing from the gist thereof.

2 Insulated wire 3 Sheath layer 4 Cable 21 Conductor 22 Insulated layer PL1 Cable fixed plate PL2 Cable fixed plate θ Angle

Claims (4)

Et styrene - consists mixture crosslinked product of elastomeric resin composition comprising as the base polymer of the ethylene copolymer of acrylic acid ester copolymer, a silane-grafted chlorinated polyethylene, the maximum static between the crosslinked product friction coefficient is less than 1.0, der less than hardness 85, measured by the a type durometer is, the chlorine content of said chlorinated polyethylene, Ru der less 40 wt% to 25 wt%, the sheath material. In the sheath material according to claim 1,
A sheath material having a mass ratio of the chlorinated polyethylene to the ethylene-based copolymer of 50:50 to 90:10. With the conductor
An insulating layer provided around the conductor and
A sheath layer provided around the insulating layer is provided.
The sheath layer, et styrene - consists mixture crosslinked product of elastomeric resin composition comprising as the base polymer of the ethylene copolymer of acrylic acid ester copolymer, a silane-grafted chlorinated polyethylene, the cross-linking maximum static frictional coefficient between the object is less than 1.0, der less than hardness 85, measured by the a type durometer is, the chlorine content of said chlorinated polyethylene, der than 40 wt% to 25 wt% Cable. In the cable according to claim 3,
A cable having a mass ratio of the chlorinated polyethylene to the ethylene-based copolymer of 50:50 to 90:10.

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