Chlorine-based rubber composition, electric wire, and cable

Abstract

To provide a chlorine-based rubber composition capable of reducing adhesiveness, and to provide an electric wire and a cable.SOLUTION: A chlorine-based rubber composition comprising: a base polymer containing a chlorine-based rubber; and a silicone lubricant to which an acrylic group is grafted, wherein a content of the silicone lubricant is 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the base polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chlorine-based rubber composition, an electric wire, and a cable. [Background technology]

[0002] Rubber materials are primarily used as covering materials for wires and cables, especially for mobile applications where flexibility and durability are required, and chlorinated rubber is known as a high-performance material with excellent flame retardancy and oil resistance. For rubber covering materials, not just chlorinated rubber, there is a strong need to reduce the tackiness (adhesion) of the surface of wire and cable covering materials for ease of application and stable handling.

[0003] For example, Patent Document 1 (JP 2023-121558 A) discloses a silane-crosslinked rubber composition, which is a silane-crosslinked product of a silane-grafted rubber composition in which a base polymer, which is a mixture of chlorinated polyethylene and an ethylene copolymer resin, is grafted with a silane coupling agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-121558 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the desired adhesive improvement effect is often not achieved.

[0006] The present invention has been made in view of the above, and an object of the present invention is to provide a chlorine-based rubber composition, an electric wire, and a cable that can reduce tackiness.

[0007] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0008] A chlorine-based rubber composition according to one embodiment of the present invention comprises a base polymer containing a chlorine-based rubber and a silicone lubricant having an acrylic group grafted thereon, and the content of the silicone lubricant is 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the base polymer. [Effects of the Invention]

[0009] One aspect of the present invention can provide a chlorine-based rubber composition, an electric wire, and a cable that can reduce tackiness. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional schematic diagram of an electric wire and a cable. [Figure 2] FIG. 2 is a schematic diagram of the cable extrusion process. [Figure 3] FIG. 3 is a schematic diagram of the friction coefficient measurement. DETAILED DESCRIPTION OF THE INVENTION

[0011] To reduce the tackiness (adhesion) of the surface of wire and cable coating materials, it is thought that adding crystallinity to rubber molecules or blending in crystalline resins is effective. However, adding crystalline components impairs the flexibility that is an inherent characteristic of rubber materials, so while adding a strong lubricant such as a silicone compound is effective, it has poor compatibility, particularly with chlorine-based rubber materials, making it difficult to fully disperse it in the composition.

[0012] Because lubricants simply having a silicone backbone are not sufficiently compatible with chlorine-based rubber compositions, the inventors of this application investigated the use of a compound in which an acrylic group has been graft-polymerized onto a silicone backbone, as a lubricant that has both a silicone backbone and a polar group. Furthermore, they investigated the practical effect of reducing tack in wire and cable coating materials and the impact of excessive lubrication on actual wire and cable manufacturing. As a result, they found the range of amounts in which a compound in which an acrylic group has been graft-polymerized onto a silicone backbone can be added to chlorine-based rubber compositions.

[0013] Hereinafter, the embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are used to designate components having the same functions, and repeated explanations thereof will be omitted. In the following embodiments, the explanations of the same or similar parts will not be repeated unless particularly necessary.

[0014] <<Chlorine-based rubber composition>> A chlorine-based rubber composition according to one embodiment will now be described. The chlorine-based rubber composition according to this embodiment contains a base polymer and a silicone lubricant.

[0015] The chlorine-based rubber composition of this embodiment can be used for covering electric wires or cables.

[0016] <Base polymer> The base polymer according to this embodiment includes a chlorine-based rubber. Examples of the chlorine-based rubber include, but are not limited to, chlorinated polyethylene, polychloroprene, and chlorosulfonated polyethylene. The chlorine-based rubber is preferably at least one selected from chlorinated polyethylene, polychloroprene, and chlorosulfonated polyethylene. The chlorine-based rubber is preferably chlorinated polyethylene. From the viewpoint of improving abrasion resistance, it is preferable to use crystalline grade chlorinated polyethylene. The chlorine content of the chlorinated polyethylene is preferably 20% by mass or more and 45% by mass or less. The Mooney viscosity of the chlorinated polyethylene is preferably 120 or less. From the viewpoint of a balance between flame retardancy and flexibility, the chlorine content of the chlorinated polyethylene is more preferably 25% by mass or more and 40% by mass or less. Furthermore, the Mooney viscosity of the chlorinated polyethylene is more preferably 90 or less.

[0017] The base polymer may further contain a polymer other than chlorine-based rubber. Examples of the polymer other than chlorine-based rubber include ethylene-based copolymers. Examples of ethylene-based copolymers include ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, and modified products or mixtures thereof. Since the vinyl acetate group, which is a polar group, of ethylene-vinyl acetate copolymers exhibits high compatibility with the chlorine in the chlorine-based rubber molecules, the ethylene-vinyl acetate copolymer is preferably used as the ethylene-based copolymer.

[0018] The melting point of the ethylene copolymer is, for example, 70°C or higher. The melting point of the ethylene copolymer is preferably 80°C or higher, and more preferably 85°C or higher. The physical properties of the ethylene copolymer resin are not limited, but for example, the melt mass flow rate (MFR) is 6g / 10min or lower. With regard to the physical properties of the ethylene copolymer resin, it is preferable that it is 1g / 10min or lower from the viewpoint of improving abrasion resistance.

[0019] The base polymer preferably has a crosslinked structure. The base polymer preferably has a silane crosslinked structure. The silane crosslinked structure can be formed by silane crosslinking the base polymer using a silane coupling agent. Examples of the silane coupling agent include general-purpose silane coupling agents that have both an organic functional group such as a vinyl group, a methacrylic group, an acrylic group, a styryl group, an amino group, or an epoxy group and an alkoxy group such as a methoxy group or an ethoxy group. Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, p-styryltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, Examples of suitable silane coupling agents include propyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and mixtures thereof. However, the silane coupling agent may be an alkoxy oligomer as long as it has both the aforementioned organic functional group and an alkoxy group, and is not limited to the above compounds.

[0020] <Silicone lubricant> In this embodiment, a silicone lubricant grafted with an acrylic group is added. By adding a silicone lubricant grafted with an acrylic group, the tackiness of the chlorine-based rubber composition can be more reliably reduced. In other words, sufficient lubricity can be imparted to the chlorine-based rubber composition. This can improve the effect of dissipating stress applied to the chlorine-based rubber composition during wear. As a result, the wear resistance of the chlorine-based rubber composition can be improved.

[0021] In this embodiment, the content of the acrylic group-grafted silicone lubricant is 0.5 parts by mass or more per 100 parts by mass of the base polymer. This makes it possible to more reliably improve the lubricity of the chlorine-based rubber composition. As a result, it is possible to improve the abrasion resistance of the chlorine-based rubber composition. In this embodiment, the content of the acrylic group-grafted silicone lubricant is 5 parts by mass or less per 100 parts by mass of the base polymer. This makes it possible to prevent a decrease in supply stability during extrusion of the electric wire / cable coating. The content of the acrylic group-grafted silicone lubricant is preferably 1 part by mass or more and 5 parts by mass or less per 100 parts by mass of the base polymer. This makes it possible to further improve the abrasion resistance of the chlorine-based rubber composition.

[0022] <Additives> The chlorine-based rubber composition of the present embodiment may further contain various additives, such as organic peroxides, hydrogen chloride scavengers, plasticizers, lubricants, reinforcing agents, fillers, flame retardants, and other additives, provided that the additives do not impair the effects of the present invention.

[0023] The organic peroxide can be used to graft silane. Examples of organic peroxides include, but are not limited to, dicumyl peroxide, 1,1-di(t-butylperoxy)cyclohexane, t-butylperoxyisopropyl carbonate, t-amylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide, di-t-amyl peroxide, 1,1-di(t-amylperoxy)cyclohexane, and t-butylperoxy-2-ethylhexyl carbonate. These can be used alone or in combination of two or more.

[0024] Hydrogen chloride scavengers can efficiently capture hydrogen chloride that may be generated from chlorine-based rubber, and examples of hydrogen chloride scavengers include epoxy group-containing compounds, hydrotalcites, lead-containing compounds such as tribasic lead sulfate, tin-containing compounds, and metal soaps.

[0025] Furthermore, adding an antioxidant or a silanol condensation catalyst to the silane-grafted rubber composition can improve heat resistance and promote the crosslinking reaction. Because antioxidants and silanol condensation catalysts can inhibit the silane-grafting reaction and cause molding defects, they are preferably mixed with the silane-grafted rubber composition during final molding (extrusion coating of the conductor or cable core in the case of electric wires and cables).

[0026] Particularly, examples of silanol condensation catalysts include elements and metal compounds of Group II elements such as magnesium and calcium, Group VIII elements such as cobalt and iron, tin, zinc, titanium, etc., metal salts of octylic acid or adipic acid, amine compounds, acids, etc. More specific examples include dioctyltin dineodecanoate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctaate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, cobalt naphthenate, ethylamine, dibutylamine, hexylamine, pyridine, inorganic acids such as sulfuric acid, and hydrochloric acid, and organic acids such as toluenesulfonic acid, acetic acid, stearic acid, and maleic acid.

[0027] The silanol condensation catalyst is preferably an octyltin compound, which is a tin-based compound with high catalytic activity and does not contain dibutyltin, which is considered to have a relatively large environmental impact. The octyltin compound is added to the chlorine-containing rubber composition in the form of a masterbatch in which the octyltin compound is mixed with a polymer. The masterbatch can chemically bond the silane coupling agent molecules by the action of moisture.

[0028] Examples of plasticizers include phthalic acid-based plasticizers such as bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and diundecyl phthalate, adipic acid-based plasticizers such as bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, and bis(2-butoxyethyl) adipate, polyester-based plasticizers, phosphoric acid-based plasticizers, epoxy-based plasticizers, and trimellitic acid-based plasticizers. These may be used alone or in combination of two or more.

[0029] In addition to the silicone lubricant grafted with an acrylic group, for example, fatty acid amide-based lubricants, zinc stearate, silicone, hydrocarbon-based lubricants, ester-based lubricants, alcohol-based lubricants, metal soap-based lubricants, etc. may be added.

[0030] Examples of the reinforcing agent include carbon black, silica, etc. The reinforcing agent is preferably carbon black.

[0031] Examples of fillers include diatomaceous earth, calcined diatomaceous earth, quartz, cristobalite, kaolinite, kaolin clay, calcined clay, talc, muscovite, wollastonite, serpentine, pyrophyllite, calcium carbonate, barium sulfate, titanium oxide, magnesium carbonate, dolomite, and aluminum oxide.

[0032] Examples of the flame retardant include metal hydroxides, halogen-based, phosphorus-based, and antimony-based flame retardants.

[0033] <Method of manufacturing chlorine-based rubber composition> An example of a method for kneading and producing a chlorine-containing rubber composition and a method for producing an electric wire or cable using the chlorine-containing rubber composition is shown below. The following composition material blend, kneading conditions, and electric wire or cable production conditions are not intended to limit the scope of the invention.

[0034] The method for producing the chlorine-based rubber composition according to the present embodiment includes, for example, kneading a silane coupling agent and various additives into a mixed base polymer of chlorinated polyethylene and ethylene-vinyl acetate copolymer, which is the chlorine-based rubber, followed by silane grafting and further crosslinking.

[0035] In order to achieve the above-mentioned kneading and grafting treatment, any commonly used kneading or reaction apparatus such as a roll mill, an extruder, a mixer, or an autoclave may be used other than a kneader, and the kneading and grafting conditions are not limited to those described above.

[0036] <Electric wire> Next, the electric wire according to this embodiment will be described. The electric wire 10 according to this embodiment has a conductor 9 and an insulating layer 11 that covers and protects the conductor 9. As shown in FIG. 1, for example, this electric wire can be an electric wire 10 in which the outer periphery of the conductor 9 is covered with the insulating layer 11. The insulating layer 11 is preferably made of the chlorine-based rubber composition described above. This can reduce the tackiness (adhesion) of the surface of the electric wire 10.

[0037] The conductor 9 may be any commonly used metal wire, such as copper wire, copper alloy wire, aluminum wire, gold wire, or silver wire. Alternatively, a metal wire plated with a metal such as nickel may be used as the conductor 9. Furthermore, a twisted conductor made by twisting metal wires may also be used as the conductor 9.

[0038] Fig. 2 is a diagram showing a schematic configuration of an example of an extruder for producing an electric wire according to this embodiment. As shown in Fig. 2, the extruder 1 includes a cylinder 5, a screw 3 rotatably provided within the cylinder 5, a hopper 2 for supplying material into the cylinder 5, and a crosshead 7. The extruder 1 also includes a neck 6 between the crosshead 7 and the screw 3. The extruder 1 also includes a breaker plate 4 between the neck 6 and the screw 3. The crosshead 7 has a die 8. A conductor 9 passing through the crosshead 7 is coated with an insulating layer within the crosshead 7, passes through the die 8, and is drawn out from the crosshead 7 as an electric wire 10.

[0039] <Cable> A cross-sectional view of a cable according to one embodiment of the present invention is shown in Fig. 1. As shown in Fig. 1, cable 13 has conductor 9, insulating layer 11, and coating layer 12. Cable 13 has three electric wires 10. The three electric wires 10 are twisted together.

[0040] The conductor 9 can be made of the same material as the conductor 9 of the above-described electric wire 10. The insulating layer 11 can be made of the same material as the insulating layer 11 of the above-described electric wire 10.

[0041] The insulating layer 11 is not particularly limited as long as it is made of an insulating material that is normally used for cables, such as an ethylene-propylene copolymer blend, polyvinyl chloride, fluororesin, cross-linked polyethylene, natural rubber, or synthetic rubber.

[0042] The covering layer 12 is preferably formed of the chlorine-based rubber composition described in the present embodiment above, which can reduce tackiness (adhesion) on the surface of the cable 13. The cable 13 can be manufactured by using an extruder to cover the outer periphery of the insulating layer 11 formed on the conductor 9 with the chlorine-based rubber composition described above.

[0043] The cable 13 in this embodiment can be produced using the extruder 1 used to produce the electric wire 10. A cable 13 having a covering layer 12 made of a chlorine-based rubber composition can be produced using the extruder 1 in the same manner as in the above-described method for producing the electric wire 10, except that the conductor 9 is replaced with the electric wire 10.

[0044] The cable 13 obtained in this way is, for example, the cable 13 having the configuration shown in FIG. 1, and in particular, in the case of a multi-core cable, it has a conductor cross-sectional area of ​​38 mm 2 as specified in the Electrical Appliance and Material Safety Law (Appendix 1) and JIS C3327. 2 It is preferable to have an electric wire of about the same size. [Example]

[0045] The following embodiments are examples in which the chlorine-based rubber composition according to the present invention is used in the wire insulator or cable sheath to produce electric wires and cables, in order to facilitate understanding of the present invention. There are no limitations on the type or structure of the conductor, or the structure or use of the electric wire or cable, such as the application of an interposed or semiconductive layer, a holding tape, a shielding braid, or a reinforcing layer.

[0046] (Mixing silane coupling agents and various additives) Chlorinated polyethylene, ethylene-vinyl acetate copolymer, silane coupling agent, organic peroxide, hydrogen chloride scavenger, plasticizer, lubricant, reinforcing agent, filler, and flame retardant were loaded into a 25 L pressure kneader (kneader tank temperature controlled at 100°C) and kneaded under pressure for 10 minutes at a rotor speed of 10 rpm. Dissolving the organic peroxide in the silane coupling agent beforehand can improve the dispersibility of the organic peroxide in the polymer. Furthermore, impregnating the reinforcing agent or other filler with the silane coupling agent during loading reduces the adsorption of the silane coupling agent to the kneader tank. Furthermore, adding the ethylene-vinyl acetate copolymer toward the end of the kneading process increases the viscosity of the material during additive kneading, improving additive dispersibility. These conditions are merely examples and are not limiting.

[0047] (Silane grafting treatment) After the kneading, the material is heated to 180°C using the same equipment (a 25 L pressure kneader with the kneader tank temperature controlled at 100°C) while kneading at a rotor speed of 30 rpm. This operation can be performed continuously without discharging the material after the kneading. After reaching 180°C, the rotation speed is reduced and the material is isothermally kneaded for 3 minutes and 30 seconds to dynamically graft the silane coupling agent onto the polymer. After grafting is complete, the material is quickly discharged into the hopper of a single-screw extruder, extruded into a strand, water-cooled, and pelletized to produce pellets of the silane graft composition. The granulation method is not limited to the above; for example, pellets can be produced using a hot-cut device without water cooling. A release agent can also be used to prevent adhesion between pellets. The release agent can be of any composition or form, such as powder, liquid, or mist. However, for economic reasons, it is effective to use talc, for example.

[0048] (Kneading of silanol condensation catalyst masterbatch) The polymer (a hydrogen chloride scavenger can be used if chlorinated rubber is included), antioxidant, and silanol condensation catalyst are placed in the same 25 L pressure kneader (kneader tank temperature controlled at 100°C) as above, and kneaded under pressure for 10 minutes at a rotation speed of 10 rpm. The polymer may be the same chlorinated polyethylene and ethylene vinyl acetate copolymer as the main material, but is not particularly limited. As with the silane grafting treatment described above, the kneaded material is granulated into pellets, and a release agent may be used to prevent the pellets from sticking together.

[0049] (Cable manufacturing and cross-linking) Furthermore, cables were manufactured using the prepared compounds and crosslinked as follows.

[0050] Conductor cross section of 38mm, consisting of multiple strands of tin-plated annealed copper wire 2A cable was fabricated by extrusion coating a conductor (outer diameter 9.1 mm) with an ethylene-propylene rubber copolymer blend as an insulator to a thickness of 1.2 mm, crosslinking the wires, and twisting three of the resulting cores into a cable core. A silane graft composition and masterbatch pellets were dry-blended in the proportions shown in Table 1 and extruded to a thickness of 3.0 mm using a single-screw extruder with a screw diameter of 90 mm to fabricate the cable (finished outer diameter approximately 31 mm). After fabrication, the cable was stored in a saturated steam atmosphere at 60°C for 24 hours to undergo a crosslinking treatment.

[0051] To achieve the above-mentioned kneading and grafting treatment, any commonly used kneading or reaction device such as a roll mill, extruder, mixer, or autoclave may be used other than a kneader, and the kneading and grafting conditions are not limited to those described above. Similarly, cable production is also an example, and the extruder, cable core, cable structure, and crosslinking conditions are not limited to those described above.

[0052] More specifically, the silane graft composition, masterbatch, and cable were produced using the equipment, cable structure, cable production extrusion conditions, and material formulation shown in Figures 1 and 2 and Tables 1 and 2. The crosslinked cables were evaluated for their properties as shown below.

[0053] [Table 1] *1 Resonac, *2 Mitsui Dow Polychemical, *3 Shin-Etsu Chemical, *4 NOF, *5 Nissin Chemical Industry Chaline R-175S, *6 Nippon Steel Carbon HTC#S (arithmetic mean particle size 68nm)

[0054] [Table 2]

[0055] (1) Adhesion between sheath materials (coefficient of static friction) After crosslinking, the cable sheath was stripped and ground from the inside (insulator side) to prepare rectangular test pieces a14 (1 mm thick, 100 mm long, and 15 mm wide) and b15 (1 mm thick, 10 mm long, and 10 mm wide). As shown in Figure 3, test piece b15 was attached with double-sided tape to a stainless steel plate 16 (weight 0.066 N), one end of which was connected to a push-pull gauge 18, so that the top surface of test piece a14 was in contact with test piece b15. The bottom surface of test piece a14 was also attached with double-sided tape to the flat surface of a work mat. A weight 17 (weight 2 N) was placed on the stainless steel plate 16, and the push-pull gauge 18 was moved at a speed of approximately 500 mm / min for a distance of at least 50 mm without vibrating. The maximum stress (= static friction force) when the stainless steel plate 16 began to move was measured, and the static friction coefficient was calculated using the following equation.

[0056] Using a rubber composition sheath that did not contain an acrylic-grafted silicone lubricant as a comparison, those that had a static friction coefficient reduction rate of less than 5% were deemed to have an insufficient adhesion-reducing effect (marked × in Table 1), those that had a reduction of 5% to 10% were deemed to have an adhesion-reducing effect (marked ○ in Table 1), and those that had a reduction of 10% or more were deemed to have an especially excellent adhesion-reducing effect (marked ◎ in Table 1), with ○ and ◎ being deemed to have passed. Coefficient of static friction = static friction force [N] / 2.066 [N] Reduction rate of static friction coefficient [%] = {(μ0-μ1) / μ0} x 100 where μ0 is the static friction coefficient of the comparison sheath, μ1 is the static friction coefficient of the sheath in question

[0057] (2) Wear resistance (grinding wheel wear volume) Measurements were carried out using the crosslinked cable according to the method specified in JIS C 3005. The weight mass was 5 kg, and the grinding wheel disc rotation speed was 750 rpm. Evaluation was carried out by calculating the depth of the worn area of ​​the cable sheath after the abrasion test using a micrometer using the following formula. A rubber composition sheath containing no acrylic-grafted silicone lubricant was used as a comparison. A reduction in wear depth of less than 2% compared to this was deemed insufficient (marked × in Table 1), a reduction of 2% to less than 10% was deemed effective (marked ○ in Table 1), and a reduction of 10% or more was deemed particularly excellent (marked ◎ in Table 1). ○ and ◎ were deemed pass. Abrasion depth [mm] = Cable outer diameter before test [mm] - Cable thickness at the abraded part after test [mm] Wear depth reduction rate [%] = {(x0-x1) / x0} x 100 where x0 is the wear depth of the comparison sheath, and x1 is the wear depth of the sheath in question.

[0058] (3) Cable extrusion workability (material supply stability) The stability of feeding a dry blend of silane graft composition and masterbatch pellets from a hopper into an extruder was evaluated. Those in which the pellets loaded into the hopper were automatically transported by the screw were rated as good (marked ○ in Table 1), while those in which the amount of pellets transported by the screw was unstable and automatic feeding was difficult due to pellet blocking in the hopper or insufficient engagement by the screw due to excessive lubricity were rated as poor (marked × in Table 1). ○ was rated as passed, and × was rated as failed.

[0059] (4) Overall Judgment In the above (1) to (2), if the reduction rate for both comparisons was acceptable (marked with ○ or ◎ in Table 1), it was deemed to have passed, and if either one was insufficient (marked with × in Table 1), it was deemed to have failed.

[0060] The examples showed that the static friction coefficient and wear depth decreased with the addition of acrylic-grafted silicone lubricant. Furthermore, it was found that adding 2.5 parts by mass of acrylic-grafted silicone lubricant significantly reduced the static friction coefficient, and adding 5 parts by mass also significantly reduced the wear depth. It was also confirmed that stable automatic supply of pellets was possible during cable extrusion under all of the example conditions.

[0061] Comparative Example 2 showed that adding too little acrylic-grafted silicone lubricant resulted in insufficient reductions in both the static friction coefficient and wear depth, while Comparative Example 3 showed that adding too much acrylic-grafted silicone lubricant resulted in pellet surfaces that were too slippery, resulting in poor screw penetration and making stable automatic feeding difficult.

[0062] From the above, it was found that in order to achieve both the effect of reducing the static friction coefficient and wear depth and cable extrusion workability, it is necessary to ensure that the amount of acrylic-grafted silicone lubricant added does not deviate from the range of 0.5 to 5 parts by mass.

[0063] According to this invention, by adding a silicone-acrylic lubricant to a chlorine-based rubber composition, it is possible to reduce the coefficient of friction between the components and improve abrasion resistance. Furthermore, by optimizing the amount added, it is possible to prevent excessive surface lubrication, while also achieving compatibility with the extrusion workability of electric wires and cables. This is believed to contribute to improving the mutual adhesion problem, which is particularly problematic with rubber-coated electric wires and cables, and to expanding into applications where abrasion resistance is highly required.

[0064] The present invention has been described using the above-mentioned embodiments and examples, but the present invention is not limited to the above-mentioned embodiments and examples and can be modified in various ways without departing from the spirit of the invention. [Explanation of symbols]

[0065] 1. Extruder 2 Hopper 3 screws 4 Breaker Plate 5 cylinders 6 Neck 7 Crosshead 8 dice 9 Conductors 10 Electric wire 11 Insulating layer 12 Covering layer 13 Cable 14 Test piece a 15 Test piece b 16 SUS board 17 Weights 18 Push-pull gauge

Claims

1. The lubricant comprises a base polymer containing a chlorine-based rubber and a silicone lubricant having an acrylic group grafted thereon, The chlorine-based rubber composition has a content of the silicone lubricant of 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the base polymer.

2. In claim 1, The chlorine-based rubber composition, wherein the chlorine-based rubber is chlorinated polyethylene.

3. In claim 1, The chlorine-based rubber composition, wherein the base polymer further contains an ethylene vinyl acetate copolymer.

4. In claim 1, The base polymer is graft-polymerized with a silane coupling agent.

5. In claim 4, The chlorine-based rubber composition further comprises a hydrogen chloride scavenger, a plasticizer, and carbon black.

6. In claim 4, The silane coupling agent is a chlorine-based rubber composition containing a methacryl group as an organic functional group.

7. In claim 4, Furthermore, the present invention includes a masterbatch in which an octyltin compound is mixed with a polymer as a silanol condensation catalyst, The masterbatch is a chlorine-based rubber composition that chemically bonds between molecules of the silane coupling agent by the action of moisture.

8. A conductor and an insulating layer covering the outer periphery of the conductor, An electric wire, wherein the insulating layer is made of the chlorine-based rubber composition according to any one of claims 1 to 7.

9. The cable includes a conductor, an insulating layer covering the outer periphery of the conductor, and a covering layer covering the periphery of the insulating layer, A cable, wherein the covering layer is made of the chlorine-based rubber composition according to any one of claims 1 to 7.

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