Cables and wires

Abstract

The present invention aims to achieve a high level of balanced flame retardancy, heat resistance, and resilience in a cable. A method for solving the problem of the present invention relates to a cable comprising a conductor, an insulating layer covering the conductor, and a sheath covering the insulating layer, wherein the sheath is formed from a flame-retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C), and a flame retardant (D), wherein the base polymer (A) comprises chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate ester, a lactone, and a carbonate ester, the stabilizer (C) comprises hydrotalcite (c1) and a metal soap (c2), and the flame retardant (D) comprises at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

Description

Technical Field

[0001] The present invention relates to cables and wires. Background Art

[0002] Cables are constructed by applying an insulating layer around a conductor, for example, and then applying a sheath (so-called a sheath) around an electric wire. The sheath is formed from a resin composition primarily composed of rubber and resin. For example, a soft vinyl chloride resin composition (soft PVC) blended with a flame retardant is used as this resin composition.

[0003] Resin compositions require different properties depending on the cable's intended use. For example, cables used in factory automation (FA) robots require flame retardancy, heat resistance, and resilience. In particular, FA robots have recently become multi-jointed and multi-axis, and the cables used are subject to repeated bending as the equipment moves, necessitating high resilience. Resilience refers to the ability of a cable to return to its original shape after being bent.

[0004] However, when soft PVC is used for the outer layer, the outer layer has low resilience, which may cause the cable to break during operation of the FA robot. Therefore, for cables requiring resilience, a resin composition in which an ether-based polyurethane thermoplastic elastomer (hereinafter also referred to as TPU) is blended with soft PVC has been proposed (see, for example, Patent Document 1). TPU can impart resilience to the outer layer.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-91975 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, even when TPU is added to the outer layer, it's sometimes difficult to achieve a high level of balanced flame retardancy, heat resistance, and resilience. Specifically, large amounts of flame retardants are sometimes added to the outer layer to achieve high flame retardancy. This large amount of flame retardant can cause the TPU's hard segments to collapse, compromising TPU's inherent heat resistance. On the other hand, reducing the amount of flame retardant added to achieve the heat resistance provided by TPU can sometimes fail to achieve the desired flame retardancy. Thus, when using TPU, while high resilience can sometimes be achieved, it's difficult to achieve both flame retardancy and heat resistance at both high and low levels.

[0010] Furthermore, the outer skin layer is required to have cold resistance such that it exhibits appropriate elasticity even in a low-temperature environment. However, when TPU is blended, sufficient cold resistance may not be obtained.

[0011] An object of the present invention is to provide a technology for achieving flame retardancy, heat resistance, resilience, and cold resistance in a cable at a high and balanced level.

[0012] Methods for solving problems

[0013] According to one aspect of the present invention, there is provided a cable including a conductor, an insulating layer covering the conductor, and an outer sheath covering the insulating layer.

[0014] The outer skin layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D).

[0015] The base polymer (A) comprises a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, a lactone-based, and a carbonate-based elastomer.

[0016] The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2),

[0017] The flame retardant (D) contains at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

[0018] According to another aspect of the present invention, there is provided an electric wire including a conductor and an insulating layer covering the conductor.

[0019] The insulating layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D).

[0020] The base polymer (A) comprises a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, a lactone-based, and a carbonate-based elastomer.

[0021] The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2),

[0022] The flame retardant (D) contains at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

[0023] Effects of the Invention

[0024] According to the present invention, it is possible to provide a cable with flame retardancy, heat resistance, resilience, and cold resistance at a high and balanced level. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a cross-sectional view perpendicular to the longitudinal direction of a cable according to one embodiment of the present invention.

[0026] Explanation of symbols

[0027] 1: cable, 10: wire, 11: conductor, 12: insulation layer, 13: shielding layer, 14: outer layer (sheath). DETAILED DESCRIPTION

[0028] <Knowledge of the present inventors>

[0029] As mentioned above, when TPU is mixed with soft PVC, large amounts of additives such as flame retardants can enter the TPU, reducing heat resistance. Furthermore, mixing soft PVC with TPU sometimes fails to achieve the desired cold resistance. Therefore, the present inventors have investigated alternative components to PVC as base polymers, as well as the types of plasticizers, stabilizers, and flame retardants that can be added thereto.

[0030] As a result, they found that it is preferable to use chlorinated polyethylene (hereinafter also referred to as CPE) and TPU together as the base polymer from the viewpoint of achieving flame retardancy, heat resistance, resilience, and cold resistance at a high level and in a balanced manner.

[0031] Furthermore, as stabilizers, hydrotalcite and metal soaps are preferred because they can be selectively dispersed in CPE. As flame retardants, at least one of metal hydroxides, brominated flame retardants, amorphous silica, and antimony trioxide is preferred because they can be selectively dispersed in CPE.

[0032] In addition, on the other hand, in order to improve the heat resistance of the outer layer, TPU has also been studied, and the results show that among TPU, adipic acid ester, lactone and carbonate TPU are preferred. Generally speaking, TPU is obtained by the reaction of polyols, diols and isocyanates, and has a hard rigid hard segment and a soft soft segment. TPU includes polyester TPU using polyester polyol as a polyol and polyether TPU using polyether polyol as a polyol. According to the research of the present inventors, from the viewpoint of heat resistance, polyester TPU is desired. In addition, it is known that polyester TPU exists in many types according to the type of polyester polyol, but from the viewpoint of each characteristic, adipic acid ester, lactone and carbonate are desired.

[0033] This material combination allows additives such as stabilizers and flame retardants to be selectively dispersed in CPE. This allows the respective properties of CPE and TPU to be utilized, while also suppressing the reduction in heat resistance caused by the addition of large amounts of additives and improving cold resistance. As a result, flame retardancy, heat resistance, resilience, and cold resistance can be achieved at a high and balanced level.

[0034] The present invention is proposed based on the above-mentioned knowledge.

[0035] <One embodiment of the present invention>

[0036] Hereinafter, a cable according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 This is a cross-sectional view perpendicular to the longitudinal direction of a cable according to one embodiment of the present invention. In addition, in this specification, a numerical range expressed using "to" means a range including the numerical values described before and after "to" as the lower limit and the upper limit.

[0037] (Flame-retardant resin composition)

[0038] First, the flame-retardant resin composition forming the outer sheath layer of the cable will be described.

[0039] The flame retardant resin composition of the present embodiment comprises a base polymer (A), a plasticizer (B), a stabilizer (C), a flame retardant (D), and other additives as needed. Specifically, the base polymer (A) comprises chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate ester, a lactone ester, and a carbonate ester. The stabilizer (C) comprises hydrotalcite (c1) and a metal soap (c2). The flame retardant (D) comprises at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

[0040] Hereinafter, each component contained in the flame-retardant resin composition will be described in detail.

[0041] (Base polymer (A))

[0042] In the present embodiment, as the base polymer (A), a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, a lactone-based, and a carbonate-based elastomer are used.

[0043] The chlorinated polyethylene (a1) is a component that contributes to improving the flame retardancy and cold resistance of the outer skin layer. The chlorinated polyethylene (a1) is obtained by blowing chlorine gas into an aqueous suspension obtained by suspending and dispersing the raw material polyethylene in water.

[0044] The chlorine content of CPE (a1) is not particularly limited, but is preferably 20% or more, more preferably 20% to 45%, from the viewpoint of improving cold resistance and flame retardancy. Furthermore, CPE (a1) may be used in combination with multiple CPEs having different chlorine contents.

[0045] The polyurethane thermoplastic elastomer (a2) is a component that primarily imparts resilience to the outer skin layer. The polyurethane thermoplastic elastomer (a2) of this embodiment is an adipate-based, lactone-based, or carbonate-based TPU. An adipate-based TPU is a TPU obtained by reacting an adipic acid-based polyester polyol with a diol and an isocyanate. A lactone-based TPU is a TPU obtained by, for example, reacting a caprolactam-based polyester polyol with a diol and an isocyanate. A carbonate-based TPU is a TPU obtained by, for example, reacting a carbonate compound-based polyester polyol with a diol and an isocyanate.

[0046] Examples of the diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerol ether, 2-monoglycerol ether, dimer alcohol, and hydrogenated dimer alcohol.

[0047] As isocyanate, known components can be used. For example, aliphatic diisocyanates such as hexamethylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, and m-tetramethylxylylene diisocyanate can be mentioned. In addition, alicyclic diisocyanates such as isophorone diisocyanate, cyclohexane-1,4-diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isopropyldicyclohexyl-4,4'-diisocyanate, and norbornane diisocyanate can be mentioned. Further examples include aromatic diisocyanates such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, toluene diisocyanate, and tetramethylxylylene diisocyanate.

[0048] From the perspective of heat resistance of the outer skin layer, TPU (a2) is not particularly limited as long as it is an adipate-based, lactone-based, or carbonate-based type. From the perspective of adjusting the hardness of the outer skin layer, an adipate-based type is preferred. Adipate-based types are not only excellent in adjusting hardness but also have superior affinity with the polyvinyl chloride resin (a1) compared to lactone-based and carbonate-based types. They facilitate the formation of the phase structure described below in the flame-retardant resin composition constituting the outer skin layer, enabling more stable and high-level performance of various properties. This is because adipate-based TPUs have a structure derived from adipic acid, so even when added with additives, the hydrogen bonding and urethane bonding strength of the hard segment are not significantly impaired, making it easier to maintain high properties.

[0049] The hardness of the adipate-based TPU (a2) is not particularly limited, but from the viewpoint of the balance between the resilience and heat resistance of the skin layer, the Shore A hardness is preferably 80A to 95A, more preferably 80A to 90A.

[0050] In addition, polymer components other than the above-mentioned components (a1) and (a2) may be appropriately blended into the base polymer (A) within a range that does not impair the properties of the outer skin layer. For example, polyvinyl chloride resins, ethylene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, styrene-based elastomers, ethylene-α-olefin copolymers, ethylene-acrylate copolymers, acrylic resins, or modified forms thereof can be used. Among them, polyvinyl chloride resins (a3) (hereinafter also referred to as PVC (a3)) are preferred from the viewpoint of excellent affinity with CPE (a1) and TPU (a2) and achieving higher levels of various properties.

[0051] As the polyvinyl chloride resin (a3), in addition to homopolymers of vinyl chloride, copolymers of vinyl chloride with other copolymerizable monomers can be used. Examples of such copolymers include copolymers of vinyl chloride with ethylene or with vinyl acetate. Furthermore, partially cross-linked compounds can be used as PVC (a3).

[0052] The average degree of polymerization of the polyvinyl chloride resin (a3) is not particularly limited, but is preferably 1000 to 3800, more preferably 1300 to 2500. By setting the average degree of polymerization to 1000 or more, the outer skin layer can obtain high heat resistance. On the other hand, if the average degree of polymerization is excessively increased, there is a concern that the molding processability of the flame retardant resin composition will decrease. By setting the average degree of polymerization to 3800 or less, the heat resistance of the outer skin layer can be improved without damaging the molding processability. In addition, as PVC (a3), multiple compounds with different average degrees of polymerization may also be used in combination.

[0053] (Plasticizer (B))

[0054] Plasticizer (B) is a component that imparts flexibility to the outer skin. As plasticizer (B), known components such as trimellitic acid ester, phthalic acid ester, adipic acid polyester can be used. Wherein, trimellitic acid ester does not damage the various characteristics of the outer skin, so it is preferred. Compared with phthalic acid ester, trimellitic acid ester can maintain the heat resistance of the outer skin higher. In addition, compared with adipic acid polyester, the outer skin will not be sticky, so the operability of the cable can be improved. Trimellitic acid ester can be used alone, or it can be used in combination with, for example, adipic acid polyester, etc., within the range of not damaging the characteristics of the outer skin.

[0055] As trimellitic acid esters, for example, tri(2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, tri-mixed alkyl trimellitate, tri-isononyl trimellitate, etc. can be used.

[0056] (Stabilizer (C))

[0057] Stabilizer (C) acts as a heat stabilizer to suppress the degradation of CPE (a1) and PVC (a3) when the flame retardant resin composition is prepared, and is a component that stabilizes the phase structure of the flame retardant resin composition. In the present embodiment, in the case of CPE (a1) or in the case of using PVC (a3), hydrotalcite (c1) and metal soap (c2) are used from the viewpoint of selectively dispersing them in the two. As hydrotalcite (c1) and metal soap (c2), as long as they have excellent compatibility with CPE (a1) and PVC (a3), there is no particular limitation, and known components can be used. As metal soap (c2), for example, components formed by fatty acids such as stearic acid, lauric acid, and caprylic acid and metals such as calcium and zinc can be used.

[0058] Furthermore, the stabilizer (C) may contain a stabilizing agent as an ingredient other than the above. The stabilizing agent is a component that acts only on the polyvinyl chloride resin (a1), regardless of whether it is added to the TPU (a2). Examples of stabilizing agents that can be used in appropriate amounts include dibenzoylmethane, stearylbenzoylmethane, and metal salts thereof, polyols, trishydroxyethyl isocyanate, silica, calcium carbonate, antioxidants, talc, and clay, as needed.

[0059] (Flame retardant (D))

[0060] The flame retardant (D) is a component that imparts flame retardancy to the outer skin layer. In this embodiment, from the perspective of dispersing the additive in the chlorinated polyethylene (a1), or when using a polyvinyl chloride resin (a3), from the perspective of selectively dispersing the additive in both CPE (a1) and PVC (a3), the flame retardant (D) is at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

[0061] As the metal hydroxide (d1), for example, magnesium hydroxide and aluminum hydroxide can be used. Among them, aluminum hydroxide is particularly preferred. In the case of magnesium hydroxide, the alkalinity in the flame retardant resin composition increases, so there is a concern that the urethane bond force, hydrogen bond force, ester bond force, etc. in the hard segment of TPU are weakened, and the heat resistance of TPU is impaired. In this regard, according to aluminum hydroxide, the alkalinity can be maintained high without excessively increasing the heat resistance. In addition, the metal hydroxide (d1) may not be surface treated, and a surface treatment such as silane treatment may also be applied. From the viewpoint of dispersibility, the average particle size of the metal hydroxide (d1) is preferably 5 μm or less. The lower limit is not particularly limited, for example, it is 0.2 μm.

[0062] As the brominated flame retardant (d2), for example, decabromodiphenyl ether, decabromodiphenyl ethane, etc. can be used. From the viewpoint of dispersibility, the average particle size of the brominated flame retardant (d2) is preferably 10 μm or less. The lower limit is not particularly limited, but is, for example, 2 μm.

[0063] The amorphous silica (d3) preferably has an average particle size of 5 μm or less from the viewpoint of dispersibility. The lower limit is not particularly limited, but is, for example, 0.01 μm.

[0064] From the viewpoint of dispersibility, the average particle size of antimony trioxide (d4) is preferably 5 μm or less. The lower limit is not particularly limited, but is, for example, 0.5 μm.

[0065] (Other additives)

[0066] The flame retardant resin composition may contain other additives in addition to components (A) to (D), such as crosslinking aids, antioxidants (thermal aging inhibitors), copper corrosion inhibitors, lubricants, and processing aids.

[0067] Specifically, examples of the crosslinking aid include trimethylolpropane trimethacrylate (TMPT), triallyl isocyanurate, triallyl cyanurate, N,N′-m-phenylene bismaleimide, ethylene glycol dimethacrylate, zinc acrylate, and zinc methacrylate.

[0068] Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants. Examples of copper corrosion inhibitors include N-(2H-1,2,4-triazol-5-yl)salicylamide, dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], and 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionhydrazide. More preferably, 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionhydrazide can be used.

[0069] Examples of the lubricant include hydrocarbon-based lubricants, fatty acid-based lubricants, fatty acid amide-based lubricants, ester-based lubricants, and alcohol-based lubricants.

[0070] Examples of the processing aid include ricinoleic acid, stearic acid, palmitic acid, lauric acid, or salts or esters thereof, and polymethyl methacrylate.

[0071] (Phase Structure)

[0072] In the flame-retardant resin composition of this embodiment, the chlorinated polyethylene (a1) and TPU (a2) form a sea-island structure or unstable dispersion by dispersing one component in the other. Furthermore, the stabilizer (C) and flame retardant (D) are more selectively dispersed in the CPE (a1) than in the TPU (a2), thereby reducing the amount of additives incorporated into the TPU (a2). This can suppress the reduction in urethane and hydrogen bonding strengths in the (a2) component. Consequently, the inherent properties of the (a2) component can be maintained at a high level.

[0073] Furthermore, when a polyvinyl chloride resin (a3) is further added as the base polymer (A), a clear sea-island structure tends to be less formed compared to when CPE (a1) and TPU (a2) are used. Furthermore, it was confirmed that the degree of selective dispersion of the additive in CPE (a1) and PVC (a3) tends to decrease compared to TPU (a2). Furthermore, it was confirmed that the combined use of PVC (a3) enables the stable and balanced achievement of various properties at a high level. The mechanism for achieving these properties is not yet clear, but it is speculated that the high compatibility between chlorinated polyethylene (a1) and polyvinyl chloride resin (a3) allows the formation of a finer and more specific phase structure by mixing these three components.

[0074] (Content ratio)

[0075] The content ratios of the components in the resin composition are as follows.

[0076] First, when using chlorinated polyethylene (a1) and TPU (a2) as the base polymer (A), it is preferable to set the following content ratio.

[0077] The base polymer (A) preferably contains 6 to 620 parts by mass of TPU, more preferably 15 to 200 parts by mass, per 100 parts by mass of the chlorinated polyethylene (a1). By mixing in such a ratio, the aforementioned phase structure is easily formed, and the desired properties are easily obtained.

[0078] The content of the chlorinated polyethylene (a1) in the flame-retardant resin composition is preferably 2% to 60%. By adding the component (a1) at such a ratio, the outer skin layer can achieve various properties at a higher level of balance.

[0079] The content of plasticizer (B) is not particularly limited. However, if the content is too low, when CPE (a1) and TPU (a2) are mixed, there is a concern that not only will the recovery be reduced, resulting in an inability to achieve a balanced balance of properties, but also that moldability and cold resistance may be reduced. Furthermore, if the content is too high, there is a concern that the tackiness of the outer skin layer may increase, leading to a decrease in moldability and flame retardancy. From the perspective of achieving a high level of balanced properties in the outer skin layer, the content of plasticizer (B) is preferably 2 to 60 parts by mass per 100 parts by mass of CPE (a1).

[0080] The content of stabilizer (C) is not particularly limited. Compared with hydrotalcite (c1), metal soap (c2) is easy to reduce the hydrogen bond force and urethane bond force in the hard segment of TPU (a2), thereby damaging the heat resistance of the outer skin layer. Therefore, from the perspective of stabilizing chlorinated polyethylene (a1) and maintaining high heat resistance, it is better to reduce the content of metal soap (c2). On the other hand, in order to ensure the effect brought by stabilizer (C), it is better to increase the content of hydrotalcite (c1). Specifically, it is preferred that the content of metal soap (c2) is less than 1.6 parts by mass relative to 100 parts by mass of chlorinated polyethylene (a1), and the content of hydrotalcite (c1) is more than 4 times the content of metal soap (c2). In addition, the lower limit of the content of metal soap (c2) is not particularly limited. If it is too little, the flame retardant resin composition is colored, or its characteristics are reduced. Therefore, it is preferably set to more than 0.01 parts by mass. The content of the hydrotalcite (c1) is not particularly limited, but is preferably 10 to 120 parts by mass relative to 100 parts by mass of CPE (a1). The total content of the stabilizer (C) is preferably 2 to 20 parts by mass.

[0081] The content of the flame retardant (D) is not particularly limited, but the total content of (d1) to (d4) is preferably 1 to 70 parts by mass per 100 parts by mass of the chlorinated polyethylene (a1). Furthermore, the content of each of (d1) to (d4) is not particularly limited as long as the total amount is within the above range, but is preferably within the following ranges: (d1) is 0 to 50 parts by mass, (d2) is 0 to 50 parts by mass, (d3) is 0 to 40 parts by mass, and (d4) is 0 to 50 parts by mass.

[0082] Next, when using chlorinated polyethylene (a1), TPU (a2) and polyvinyl chloride resin (a3) as the base polymer (A), it is preferable to set it as the following content ratio.

[0083] The base polymer (A) preferably contains 20 to 1700 parts by mass of TPU (a2) and 3 to 900 parts by mass of polyvinyl chloride resin (a3) per 100 parts by mass of chlorinated polyethylene (a1). More preferably, the base polymer (A) contains 30 to 1700 parts by mass of TPU (a2) and 4 to 900 parts by mass of PVC (a3).

[0084] When a compound other than the polyvinyl chloride resin (a3) is used as another polymer, the amount thereof added may be within the same range as that of PVC (a3).

[0085] The content of the chlorinated polyethylene (a1) in the flame-retardant resin composition is preferably 2% to 60%. By adding the component (a1) at such a ratio, the outer skin layer can achieve various properties at a higher level of balance.

[0086] Relative to 100 parts by mass of chlorinated polyethylene (a1), the content of each of the plasticizer (B), stabilizer (C) and flame retardant (D) is preferably in the following range. That is, the content of the plasticizer (B) is preferably 2 to 600 parts by mass, the stabilizer (C) is 5 to 150 parts by mass, and the flame retardant (D) is 5 to 350 parts by mass. The content of the metal soap (c2) is preferably 1 to 21 parts by mass. The content of the hydrotalcite (c1) is preferably 4 times or more of the content of the metal soap (c2), preferably 10 to 120 parts by mass. In addition, for the components (d1) to (d4) of the flame retardant (D), it is preferred that (d1) is 0 to 100 parts by mass, (d2) is 0 to 50 parts by mass, (d3) is 0 to 50 parts by mass, and (d4) is 0 to 100 parts by mass.

[0087] (Preparation of flame-retardant resin composition)

[0088] The flame-retardant resin composition is preferably prepared by mixing the above-mentioned (A) to (D) and other additives as needed, and melt-kneading them. Kneading is preferably carried out using a known kneading apparatus such as a Banbury mixer, a batch kneader such as a pressure kneader, or a continuous kneader such as a twin-screw extruder.

[0089] Specifically, chlorinated polyethylene (a1), a plasticizer (B), a stabilizer (C), and a flame retardant (D) are first kneaded to obtain CPE particles. The resulting CPE particles are then mixed with TPU (a2) and melt-kneaded. This allows the TPU (a2) to be dispersed in the CPE mixture, or the CPE mixture to be dispersed in the TPU (a2), to form a flame-retardant resin composition. By pre-mixing the CPE particles in the flame-retardant resin composition, the incorporation of additives into the TPU (a2) phase can be reduced. This allows the heat resistance of the outer skin layer to be maintained at a higher level.

[0090] When using polyvinyl chloride resin (a3), it is preferable to mix it with CPE (a1) and form it into pellets before mixing with TPU (a2). Alternatively, a powdered product of CPE (a1) in which a plasticizer (B) is compatible with PVC (a3) and a stabilizer (C) is dispersed may be mixed, or TPU (a2) may be mixed and kneaded into pellets obtained by melt-kneading these. In this case, the formation of lumps when CPE (a1) and plasticizer (B) come into contact can be appropriately suppressed, thereby improving the supply efficiency of the material.

[0091] Furthermore, even when the various materials are mixed and melt-kneaded, CPE (a1) and PVC (a3) melt at lower temperatures than TPU (a2), so various additives are more easily dispersed in the (a1) and (a3) components than in the (a2) component. However, as described above, by pre-preparing the CPE particles, the incorporation of additives into the (a2) component can be further reduced.

[0092] (cable)

[0093] Next, for the cable of this embodiment, use Figure 1 Provide explanation. Figure 1 This is a cross-sectional view perpendicular to the longitudinal direction of a cable according to one embodiment of the present invention.

[0094] like Figure 1 As shown, the cable 1 of this embodiment includes an electric wire 10 having an insulating layer 12 formed around a conductor 11 , a shield layer 13 provided around the electric wire 10 , and an outer layer 14 (sheath 14 ) formed around the shield layer 13 .

[0095] (conductor)

[0096] As the conductor 11, in addition to commonly used metal wires such as copper wire and copper alloy wire, aluminum wire, gold wire, silver wire, etc. can be used. Furthermore, as the conductor 11, a conductor in which the periphery of the metal wire is plated with a metal such as tin or nickel can be used. Furthermore, as the conductor 11, a twisted wire formed by twisting metal wires can be used.

[0097] (Insulation layer)

[0098] Insulating layer 12 is provided around conductor 11. Insulating layer 12 can be formed from a mixture containing conventionally known materials, such as fluororesins, polyester resins, high-density polyethylene, flame retardants, antioxidants, etc., or from the flame-retardant resin composition used to form the outer skin layer. The thickness of insulating layer 12 is not particularly limited, but is preferably 0.1 mm to 1.5 mm, for example.

[0099] (Shielding layer)

[0100] The shield layer 13 is provided around a twisted wire formed by twisting a plurality of electric wires 10. The shield layer 13 is formed of a braided structure obtained by braiding a plurality of metal wires such as annealed copper wires, for example.

[0101] (cortex)

[0102] The outer skin layer 14 is formed from the flame-retardant resin composition and is provided around the shield layer 13. The thickness of the outer skin layer 14 is not particularly limited, but is preferably 0.1 mm to 1.4 mm from the viewpoint of achieving various properties at a high level and in a balanced manner.

[0103] To improve the oil resistance of the outer skin layer 14 and the flame extinguishing stability during combustion, the flame-retardant resin composition may be cross-linked. The cross-linking method is not particularly limited, and electron beam cross-linking, for example, can be employed. When electron beam cross-linking is employed, the extruded flame-retardant resin composition is preferably cross-linked by irradiating the composition with electron beams at a dose of 0.5 to 30 Mrad.

[0104] (Cable Manufacturing Method)

[0105] First, a conductor 11 is prepared. Using an extruder, for example, a flame-retardant resin composition is extruded around the conductor 11 to form an insulating layer 12 of a predetermined thickness, thereby producing an electric wire 10. Subsequently, multiple electric wires 10 are twisted together, and a braiding machine is used to form a shielding layer 13 around the twisted wires. Next, using an extruder, a flame-retardant resin composition is extruded around the shielding layer 13 to form an outer sheath 14 of a predetermined thickness. This allows the production of the cable 1 of this embodiment.

[0106] <Effects of the present embodiment>

[0107] According to this embodiment, one or more of the following effects are achieved.

[0108] According to the cable 1 of this embodiment, the flame-retardant resin composition forming the outer sheath layer 14 includes, as a base polymer (A), a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, lactone-based, and carbonate-based elastomer. Furthermore, the composition includes, as stabilizers (C), hydrotalcite (c1) and a metal soap (c2), and as flame retardants (D), at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4). Components (C) and (D) are more selectively dispersed in the chlorinated polyethylene (a1) than in the TPU (a2), thus reducing the incorporation of additives into the TPU (a2). Consequently, the reduction in urethane and hydrogen bonding strengths in the (a2) component due to the incorporation of additives can be suppressed. As a result, the resilience provided by component (a2) can be achieved while maintaining the high heat resistance of the outer sheath layer 14. Furthermore, since at least one component (a2) selected from the group consisting of an adipate ester, a lactone, and a carbonate ester is used as the TPU, the heat resistance of the outer skin layer 14 can be maintained at a higher level. Furthermore, the combination of the plasticizer (B) and the stabilizer (C) allows the inherent properties of the components (a1) and (a2) to be maintained at a high level without significant impairment. Furthermore, the flame retardant (D) can enhance the flame retardancy of the outer skin layer 14. Therefore, the cable 1 of this embodiment can achieve a high and balanced level of resilience, heat resistance, flame retardancy, and cold resistance.

[0109] Specifically, the cable 1 of this embodiment has high flame retardancy, sufficient to pass the vertical flame retardancy test VW-1 specified in the UL1581 flame retardancy standard. Furthermore, it has high heat resistance, meeting the 105°C rating specified in the UL standard. Furthermore, it has high resilience, allowing it to withstand breakage when used as a cable for factory automation robots. Furthermore, it exhibits high cold resistance, remaining intact even at -50°C in the embrittlement test described below.

[0110] Furthermore, the flame-retardant resin composition can achieve flame retardancy, heat resistance, resilience, and cold resistance at a higher level in a balanced and stable manner by further comprising a polyvinyl chloride resin (a3) as the base polymer (A).

[0111] The TPU (a2) is preferably an adipate-based TPU. Adipate-based TPUs can appropriately adjust the hardness of the skin layer compared to lactone-based and carbonate-based TPUs.

[0112] The plasticizer (B) is preferably a trimellitic acid ester. The trimellitic acid ester can maintain high heat resistance of the outer skin layer.

[0113] Furthermore, the content of the plasticizer (B) is preferably 2 to 60 parts by mass per 100 parts by mass of CPE (a1). When used in combination with PVC (a3), the content is preferably 2 to 600 parts by mass per 100 parts by mass of CPE (a1). By adopting such a content, the heat resistance, flame retardancy, and resilience of the outer skin layer can be maintained at higher levels.

[0114] Furthermore, the content of the flame retardant (D) is preferably 1 to 70 parts by mass per 100 parts by mass of CPE (a1). When used in combination with PVC (a3), the content is preferably 5 to 350 parts by mass per 100 parts by mass of CPE (a1). By adopting such a content, the heat resistance, flame retardancy, and resilience of the outer skin layer can be maintained at higher levels.

[0115] Furthermore, it is preferred that the content of hydrotalcite (c1) is at least four times the content of metal soap (c2), that the content of metal soap (c2) is 1.6 parts by mass or less per 100 parts by mass of CPE (a1), and that the content of hydrotalcite (c1) is 10 to 120 parts by mass. When PVC (a3) is used in combination, it is preferred that the content of metal soap (c2) is 21 parts by mass or less per 100 parts by mass of CPE (a1), and that the content of hydrotalcite (c1) is 10 to 120 parts by mass. This can suppress the decrease in hydrogen bonding and urethane bonding of TPU (a2), and maintain high heat resistance of the outer skin layer 14.

[0116] Furthermore, according to the cable 1 of this embodiment, since TPU (a2) is blended into the outer skin layer 14, oil resistance and cold resistance can be improved compared to the case where only PVC is blended.

[0117] The content of the chlorinated polyethylene (a1) in the flame-retardant resin composition is preferably 2% to 60%. By containing the component (a1) at such a ratio, the outer skin layer 14 can achieve various properties at a higher level of balance.

[0118] The chlorine content of the chlorinated polyethylene (a1) is preferably 20% or more. Such chlorinated polyethylene (a1) has an excellent balance between flame retardancy and cold resistance, and thus the outer skin layer 14 can achieve various properties at a higher level of balance.

[0119] In this embodiment, since the two components (a1) and (a2) of the base polymer (A) are used together to form a polymer alloy, the surface of the outer skin layer 14 can be provided with desired irregularities, thereby reducing the surface friction resistance of the cable 1 .

[0120] In addition, in this embodiment, the flame retardant resin composition is used for the outer sheath layer of the cable, but the present invention is not limited thereto. For example, the flame retardant resin composition can also be used for the insulation layer of the electric wire.

[0121] Example

[0122] Next, the present invention will be described in further detail based on examples, but the present invention is not limited to these examples.

[0123] Materials

[0124] In this embodiment, the materials used for the flame-retardant resin composition for the outer skin layer are as follows.

[0125] As the chlorinated polyethylene (a1), the following were used.

[0126] Chlorinated polyethylene 1 (product name "Elaslen 352GB", manufactured by Showa Denko K.K., chlorine content: 34% to 37%)

[0127] Chlorinated polyethylene 2 (product name "Elaslen 301A", manufactured by Showa Denko K.K., chlorine content 30% to 33%)

[0128] Chlorinated polyethylene 3 (product name "Elaslen 401A", manufactured by Showa Denko K.K., chlorine content: 38% to 41%)

[0129] As the adipate-type polyurethane thermoplastic elastomer (a2), the following were used.

[0130] Adipate-type TPU1 (product name "P25MRWJE", manufactured by Miractran Co., Ltd., Japan, Shore A hardness 90)

[0131] As polymer components other than the above-mentioned components (a1) and (a2), the following were used.

[0132] As the polyvinyl chloride resin (a3), the following were used.

[0133] Polyvinyl chloride resin 1 (product name "TH-1700", manufactured by Taiyo Vinyl Chloride Co., Ltd., average degree of polymerization 1600-1800)

[0134] Furthermore, as components other than the component (a3), the following were used.

[0135] Ethylene-vinyl chloride copolymer (product name "TE-1300", manufactured by Sekisui Chemical Co., Ltd.)

[0136] Styrene-based elastomer (product name "SOES1606", manufactured by Asahi Kasei Chemicals Corporation)

[0137] Ethylene-α-olefin copolymer (product name "TAFMER DF540", manufactured by Mitsui Chemicals, Inc.)

[0138] Modified ethylene-α-olefin copolymer (product name "TAFMER MH7020", manufactured by Mitsui Chemicals, Inc.)

[0139] Ethylene-vinyl acetate copolymer EVA1 (product name "45LX", manufactured by Mitsui DuPont Polychemicals, Ltd.)

[0140] Ethylene-vinyl acetate copolymer EVA2 (product name "Levapren 500", manufactured by LANXESS Corporation)

[0141] Ethylene-ethyl acrylate copolymer EEA (product name "REXPEARL 1150", manufactured by Mitsubishi Chemical Corporation)

[0142] Acrylic resin (polymethyl methacrylate resin PMMA) (product name "METABLEN P1050", manufactured by Mitsubishi Chemical Corporation)

[0143] As the plasticizer (B), the following were used.

[0144] Tris(2-ethylhexyl) trimellitate (TOTM) (product name "T08", manufactured by Kao Corporation)

[0145] Trioctyl trimellitate (n-TOTM) (product name "N08", manufactured by Kao Corporation)

[0146] Adipic acid polyester (product name "P1030", manufactured by ADEKA Corporation)

[0147] As the hydrotalcite (c1) of the stabilizer (C), the following was used.

[0148] Hydrotalcite (product name "HT-1", manufactured by Sakai Chemical Co., Ltd.)

[0149] As the metal soap (c2) of the stabilizer (C), the following were used.

[0150] Zinc stearate (product name "SZ-P", manufactured by Sakai Chemical Co., Ltd.)

[0151] Calcium stearate (product name "SC-P", manufactured by Sakai Chemical Co., Ltd.)

[0152] As other components of the stabilizer (C), the following substances were used.

[0153] Stabilizing agents (including β-diketone, etc.)

[0154] As the metal hydroxide (d1) of the flame retardant (D), the following were used.

[0155] Untreated aluminum hydroxide (product name "BF013", manufactured by Nippon Light Metal Co., Ltd.)

[0156] Silane-treated aluminum hydroxide (product name "BF013STV", manufactured by Nippon Light Metal Co., Ltd.)

[0157] As the brominated flame retardant (d2) of the flame retardant (D), the following were used.

[0158] Brominated flame retardant (decabromodiphenylethane, product name "Saytex 8010", manufactured by Albemarle Corporation, average particle size 5.6 μm)

[0159] As the amorphous silica (d3) of the flame retardant (D), the following were used.

[0160] Amorphous silica (product name "SIDISTAR 120U", manufactured by Elkem Co., Ltd., average particle size 0.15 μm)

[0161] As antimony trioxide (d4) of the flame retardant (D), the following were used.

[0162] Antimony trioxide (product name "NANO200", manufactured by Changde Chenzhou Company, average particle size 0.8μm)

[0163] As other additives, the following substances were used.

[0164] Cross-linking aid (trimethylolpropane trimethacrylate, product name "TMPT", manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0165] Burnt clay (product name "SP#33", manufactured by BASF)

[0166] Black colorant (product name "NBP2425", manufactured by Nichihiro VICS Co., Ltd.)

[0167] White colorant (product name "Titanium White R820", manufactured by Ishihara Sangyo Co., Ltd.)

[0168] Antioxidant (product name "AO-26", manufactured by ADEKA Co., Ltd.)

[0169] <Example 1>

[0170] First, a conductor, a resin composition for forming an insulating layer, and a flame-retardant resin composition for forming an outer layer are prepared.

[0171] As the conductor, a 28AWG (19 / 0.08) TA conductor was used.

[0172] As the resin composition for forming the insulating layer, a composition containing ETFE (ethylene tetrafluoride-ethylene copolymer) as a fluororesin was used.

[0173] The flame-retardant resin composition for forming the outer skin layer was prepared by mixing and kneading the above materials to obtain the composition shown in Table 1 below. Specifically, 100 parts by mass of chlorinated polyethylene 1 and 41.8 parts by mass of adipate-type TPU 1 as the base polymer (A), 30.0 parts by mass of TOTM as the plasticizer (B), 11.66 parts by mass of hydrotalcite (c1) as the stabilizer (C), 1.14 parts by mass of zinc stearate as the metal soap (c2), 1.2 parts by mass of a stabilizing aid, 5.0 parts by mass of untreated aluminum hydroxide (d1) and 8.0 parts by mass of antimony trioxide (d4) as the flame retardant (D), and other additives, including 1.0 part by mass of a crosslinking aid, 5.2 parts by mass of calcined clay, 3.5 parts by mass of a black colorant, and 0.5 parts by mass of a white colorant, totaling 209.0 parts by mass, were kneaded to prepare the flame-retardant resin composition of Example 1. In Example 1, the flame-retardant resin composition was prepared so that the ratio of the chlorinated polyethylene (a1) to the total amount ((a1) / total amount) was 0.48. The flame-retardant resin composition was prepared by melt-kneading at a take-off temperature of 165°C using a pressure kneader, cutting into strands, and then drying at 80°C for 2 hours.

[0174] Next, a 40 mm extruder for wire manufacturing was used to extrude a resin composition for forming an insulating layer around the conductor to form an insulating layer with a thickness of 0.2 mm. Thus, an electric wire was obtained. Five electric wires were then twisted together, and a braiding machine was used to twist rayon and polyester tape (1 / 4 turn) (right-hand twist) around them to form a shielding layer. Next, a 65 mm single-shaft extruder for wire manufacturing was used to extrude a flame-retardant resin composition around the shielding layer by a tube extrusion method to form an outer skin layer with a thickness of 1 mm. Thus, the cable of Example 1 was produced.

[0175] [Table 1]

[0176]

[0177] <Examples 2 to 6>

[0178] In Examples 2 to 6, cables were produced in the same manner as in Example 1 except that the types and blending amounts of the components (A) to (D) were appropriately changed as shown in Table 1.

[0179] Comparative Examples 1 to 3

[0180] In Comparative Examples 1 and 2, as shown in Table 1, cables were produced in the same manner as in Example 1, except that chlorinated polyethylene (a1) was not used, and adipate-based TPU (a2) and polyvinyl chloride resin (a3) were used. Furthermore, in Comparative Example 3, a cable was produced in the same manner as in Example 1, except that chlorinated polyethylene (a1) and flame retardant (D) were not used.

[0181] <Examples 7 to 17>

[0182] In Examples 7 to 17, cables were produced in the same manner as in Example 1 except that chlorinated polyethylene (a1), adipate-based TPU (a2), and polyvinyl chloride resin (a3) were used and the contents of the components were appropriately changed as shown in Table 2 below.

[0183] <Examples 18 to 22>

[0184] In Examples 18 to 22, cables were produced in the same manner as in Example 1, except that the other polymer component was changed to the polymers described in Table 2 instead of the polyvinyl chloride resin (a3).

[0185] [Table 2]

[0186]

[0187] <Evaluation>

[0188] The heat resistance, flame retardancy, resilience, and cold resistance of the cables produced in Examples 1 to 22 and Comparative Examples 1 to 3 were evaluated. Each evaluation was performed as follows.

[0189] (Heat resistance)

[0190] Heat resistance was evaluated using a test in accordance with UL1581. Specifically, samples (approximately 100 mm in length) containing only the outer sheath layer of the manufactured cable were prepared and exposed in a 136°C Girth oven for 168 hours. The initial tensile strength and elongation were compared with those after exposure. The tensile strength retention (%) and elongation retention (%) were then calculated using the following formulas. A tensile strength retention of 70% or greater and an elongation retention of 45% or greater were considered "passed." A failure to meet either or both of these criteria was considered "failed."

[0191] Tensile strength retention (%) = 100 × (tensile strength after exposure) / (initial tensile strength)

[0192] Residual elongation (%) = 100 × (elongation after exposure) / (initial elongation)

[0193] (Flame retardancy)

[0194] Flame retardancy was evaluated using tests in accordance with UL 1581. Specifically, the vertical flame retardancy test VW-1 specified in UL 1581 was performed three times on the manufactured cable (approximately 500 mm in length). A cable meeting the criteria all three times was deemed "passed," while a cable failing to meet the criteria even once was deemed "failed."

[0195] (Resilience)

[0196] Resilience is evaluated by the following method. First, the outer cortex collected by each cable is punched into a dumbbell shape to obtain a test piece. Then, using a tensile testing machine, the test piece is stretched to 100% with a line spacing of 25mm and a pulling speed of 200mm / minute. The testing machine is then stopped and the dumbbell is disengaged. After measuring 10 seconds, how much (X value) the line spacing of 25mm has stretched. And, the degree of recovery (Y) is calculated by the following formula. In the present embodiment, the Y value is set to be qualified if it is more than 84, and unqualified if it is less than 84. In addition, because the degree of recovery Y shows a certain degree of correlation with the repulsion elastic modulus, it is confirmed as an index of resilience.

[0197] Y=-4*X+200

[0198] (cold resistance)

[0199] Cold resistance was evaluated using the following test. Specifically, the outer sheath was removed from the manufactured cable to obtain a sample, which was then subjected to a fracture test using a brittleness tester. In this example, samples that did not break even at -50°C were considered "passed," while samples that broke at temperatures above -50°C were considered "failed."

[0200] <Evaluation Results>

[0201] The evaluation results of the heat resistance, flame retardancy, and recovery properties of the cables are summarized in Tables 1 and 2.

[0202] In Comparative Examples 1 and 2, the recovery property and cold resistance were found to be reduced due to the absence of the chlorinated polyethylene (a1). In Comparative Example 3, the flame retardancy was also found to be reduced due to the absence of the flame retardant (D).

[0203] In contrast, Examples 1 to 6 confirmed that heat resistance, flame retardancy, resilience, and cold resistance were achieved at a high and balanced level. Specifically, it was confirmed that various properties could be improved by blending a chlorinated polyethylene (a1) having a chlorine content of 20% or more so as to have a content ratio in the flame-retardant resin composition within a range of 2% to 60%.

[0204] In Examples 7 to 17, it was confirmed that the use of the chlorinated polyethylene (a1), the adipate-based TPU (a2), and the polyvinyl chloride resin (a3) allowed various properties to be obtained more stably and at a higher level than in Example 1 and the like.

[0205] Furthermore, Examples 18 to 22 confirmed that even ethylene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, styrene-based elastomers, ethylene-α-olefin copolymers, ethylene-acrylate copolymers, acrylic resins, or modified forms thereof other than the polyvinyl chloride resin (a3) can achieve various properties at a high level and in a balanced manner, similar to the polyvinyl chloride resin (a3).

[0206] As described above, by using the above-described combination of the base polymer (A), plasticizer (B), plasticizer (C), and flame retardant (D), the outer sheath layer can achieve a high level of balanced heat resistance, flame retardancy, resilience, and cold resistance. Cables having such outer sheath layers can be used as factory automation (FA) robot cables.

[0207] <Preferred Embodiments of the Invention>

[0208] Hereinafter, preferred embodiments of the present invention will be described in addition.

[0209] [Note 1]

[0210] One embodiment of the present invention relates to a cable including a conductor, an insulating layer covering the conductor, and an outer layer covering the insulating layer.

[0211] The outer skin layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D).

[0212] The base polymer (A) comprises a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, a lactone-based, and a carbonate-based elastomer.

[0213] The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2),

[0214] The flame retardant (D) contains at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

[0215] [Note 2]

[0216] According to Supplementary Note 1, the base polymer (A) preferably contains 6 parts by mass or more and 620 parts by mass or less of the polyurethane thermoplastic elastomer (a2) per 100 parts by mass of the chlorinated polyethylene (a1).

[0217] [Note 3]

[0218] According to Supplementary Note 2, the content of the chlorinated polyethylene (a1) in the flame-retardant resin composition is preferably 2% to 60%.

[0219] [Note 4]

[0220] According to any one of Supplements 1 to 3, the content of the hydrotalcite (c1) is preferably 4 times or more the content of the metal soap (c2), and the content of the metal soap (c2) is preferably 1.6 parts by mass or less per 100 parts by mass of the chlorinated polyethylene (a1).

[0221] [Note 5]

[0222] According to any one of Supplements 1 to 4, the content of the plasticizer (B) is preferably 2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the chlorinated polyethylene (a1).

[0223] [Note 6]

[0224] According to any one of Supplementary Notes 1 to 5, the content of the stabilizer (C) is preferably 2 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the chlorinated polyethylene (a1).

[0225] [Note 7]

[0226] According to any one of Supplements 1 to 6, the content of the flame retardant (D) is preferably 1 part by mass or more and 70 parts by mass or less based on 100 parts by mass of the chlorinated polyethylene (a1).

[0227] [Note 8]

[0228] According to Supplementary Note 1, the base polymer (A) preferably further comprises a polyvinyl chloride resin (a3), and preferably comprises 20 parts by mass to 1700 parts by mass of the polyurethane thermoplastic elastomer (a2) and 3 parts by mass to 900 parts by mass of the polyvinyl chloride resin (a3) per 100 parts by mass of the chlorinated polyethylene (a1).

[0229] [Note 9]

[0230] According to Supplementary Note 8, the content of the chlorinated polyethylene (a1) in the flame-retardant resin composition is preferably 2% to 60%.

[0231] [Note 10]

[0232] According to Supplementary Note 8 or 9, the content of the hydrotalcite (c1) is preferably 4 times or more the content of the metal soap (c2), and the content of the metal soap (c2) is preferably 21 parts by mass or less per 100 parts by mass of the chlorinated polyethylene (a1).

[0233] [Note 11]

[0234] According to any one of Supplementary Notes 8 to 10, the content of the plasticizer (B) is preferably 2 parts by mass or more and 600 parts by mass or less based on 100 parts by mass of the chlorinated polyethylene (a1).

[0235] [Note 12]

[0236] According to any one of Supplementary Notes 8 to 11, the content of the stabilizer (C) is preferably 5 parts by mass or more and 150 parts by mass or less based on 100 parts by mass of the chlorinated polyethylene (a1).

[0237] [Note 13]

[0238] According to any one of Supplementary Notes 8 to 12, the content of the flame retardant (D) is preferably 5 parts by mass or more and 350 parts by mass or less based on 100 parts by mass of the chlorinated polyethylene (a1).

[0239] [Note 14]

[0240] According to any one of Supplementary Notes 1 to 13, the chlorine content of the chlorinated polyethylene (a1) is preferably 20% or more.

[0241] [Note 15]

[0242] According to any one of Appendixes 1 to 14, the polyurethane thermoplastic elastomer (a2) is preferably an adipate-based elastomer.

[0243] [Note 16]

[0244] According to any one of Appendixes 1 to 15, it is preferred that the plasticizer (B) contains trimellitic acid ester.

[0245] [Note 17]

[0246] According to any one of Supplementary Notes 1 to 16, it is preferred that the thickness of the skin layer is 0.1 mm or more and 1.4 mm or less.

[0247] [Note 18]

[0248] According to any one of Supplementary Notes 1 to 17, it is preferred that the average degree of polymerization of the polyvinyl chloride resin (a3) is 1,000 to 3,800.

[0249] [Note 19]

[0250] According to any one of Supplementary Notes 1 to 18, the polyurethane thermoplastic elastomer (a2) preferably has a Shore A hardness of 80A to 95A.

[0251] [Note 20]

[0252] Another aspect of the present invention relates to an electric wire including a conductor and an insulating layer covering the periphery of the conductor.

[0253] The insulating layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D).

[0254] The base polymer (A) comprises a chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of an adipate-based, a lactone-based, and a carbonate-based elastomer.

[0255] The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2),

[0256] The flame retardant (D) contains at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silica (d3), and antimony trioxide (d4).

Claims

1. A cable comprising a conductor, an insulating layer covering the conductor, and an outer layer covering the insulating layer. The outer skin layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D), The base polymer (A) comprises chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of adipate-based, lactone-based, and carbonate-based elastomers. The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2), The flame retardant (D) comprises at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silicon dioxide (d3), and antimony trioxide (d4). The base polymer (A) further contains a polyvinyl chloride resin (a3), and contains 164.00 parts by mass or more and 1700 parts by mass or less of the polyurethane thermoplastic elastomer (a2) and 3 parts by mass or more and 233.33 parts by mass or less of the polyvinyl chloride resin (a3) per 100 parts by mass of the chlorinated polyethylene (a1). 2 . The cable according to claim 1 , wherein the polyurethane thermoplastic elastomer (a2) is an adipate-based elastomer. 3 . The cable according to claim 1 , wherein the plasticizer (B) comprises trimellitic acid ester. The cable according to claim 1 or 2, wherein the chlorine content of the chlorinated polyethylene (a1) is 20% or more. The cable according to claim 1 or 2, wherein the thickness of the outer skin layer is not less than 0.1 mm and not more than 1.4 mm.

6. An electric wire comprising a conductor and an insulating layer covering the periphery of the conductor. The insulating layer is formed of a flame retardant resin composition comprising a base polymer (A), a plasticizer (B), a stabilizer (C) and a flame retardant (D), The base polymer (A) comprises chlorinated polyethylene (a1) and at least one polyurethane thermoplastic elastomer (a2) selected from the group consisting of adipate-based, lactone-based, and carbonate-based elastomers. The stabilizer (C) comprises hydrotalcite (c1) and metal soap (c2), The flame retardant (D) comprises at least one of a metal hydroxide (d1), a brominated flame retardant (d2), amorphous silicon dioxide (d3), and antimony trioxide (d4). The base polymer (A) further contains a polyvinyl chloride resin (a3), and contains 164.00 parts by mass or more and 1700 parts by mass or less of the polyurethane thermoplastic elastomer (a2) and 3 parts by mass or more and 233.33 parts by mass or less of the polyvinyl chloride resin (a3) per 100 parts by mass of the chlorinated polyethylene (a1).

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