Resin composition, resin coating material, insulated wire, automotive wire harness, and method for manufacturing insulated wire for automotive wire harness

Abstract

A resin composition including the following components (A) and (B) and containing the following component (C) and / or the following component (D): (A) a low-density polyethylene resin, (B) an ethylene / vinyl acetate copolymer resin, (C) a thioether compound, and (D) a fluororubber. The content of the component (A) and the content of the component (B) are 5-40 parts by mass and 60-95 parts by mass, respectively, per 100 parts by mass of the sum of the components (A) and (B). The total content of the components (C) and (D) is 0.05-1 part by mass per 100 parts by mass of the sum of the components (A) and (B). In the component (B), the proportion of vinyl acetate units is 40 mass% or less.

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a resin coating material, an insulated wire, an automotive wire harness, and a method for producing an insulated wire used in an automotive wire harness. [Background technology]

[0002] Flame-retardant insulated wires are widely used in various home appliances, office automation equipment, etc. Insulated wires used in automobiles and other applications are also required to have various properties, such as flame retardancy, heat resistance, flexibility, and mechanical properties. To date, many studies have been conducted on resin compositions that, when used as a coating material for conductors, can provide insulated wires with flame retardancy, heat resistance, flexibility, and mechanical properties, and many reports have been published. As a resin composition for forming an insulated wire having such desired properties, resins such as polyethylene and ethylene-vinyl acetate copolymer are widely used.

[0003] For example, Patent Document 1 describes that a flame-retardant electric wire having excellent flame retardancy, water resistance, and oil resistance can be obtained by using a resin composition containing an ethylene-vinyl acetate copolymer having a vinyl acetate content within a specific range, a bromine-based flame retardant, an epoxy compound, and antimony trioxide as a coating material for a conductor and crosslinking the resin composition.

[0004] Patent Document 2 describes a resin composition that can be used as a coating material for a conductor to obtain an insulated wire having an insulating layer with excellent flexibility, oil resistance, and mechanical strength. This resin composition has a density within a specific range and contains a copolymer of an unsaturated hydrocarbon having 4 or more carbon atoms and ethylene, a copolymer of an acrylic acid ester and ethylene or a copolymer of a methacrylic acid ester and ethylene, a flame retardant, and a cross-linking aid in specific amounts.

[0005] Patent Document 3 describes a halogen-free, flame-retardant resin composition for use in forming an insulating coating on an insulated electric wire, which exhibits excellent flame retardancy, heat resistance, cold resistance (low-temperature characteristics), and oil resistance, as well as excellent mechanical strength such as tensile mechanical properties and abrasion resistance, all of which are well-balanced. This resin composition contains, per 100 parts by mass of polyolefin resin, 100 to 250 parts by mass of a metal hydroxide and 1 to 20% by mass of a silicone oil having a viscosity of 3000 mPa·s or less at 25°C. The polyolefin resin contains 30 to 85% by mass of polyethylene having a melting point (Tm) measured by DSC method of 120 to 130°C and a density of 0.925 to 0.945, 10 to 60% by mass of ethylene-vinyl acetate copolymer (EVA), and 5 to 30% by mass of a maleic anhydride-modified ethylene-α-olefin copolymer having a melting point measured by DSC method of 60°C or less.

[0006] Patent Document 4 describes an insulated wire and cable made of a halogen-free flame-retardant resin composition that is flame-retardant and has excellent oil and fuel resistance and external damage resistance. This halogen-free flame-retardant resin composition contains, as a base polymer, 60 to 70 mass% of linear low-density polyethylene, 10 mass% or more of an ethylene-vinyl acetate copolymer having a melt flow rate (MFR) of 100 or more, and 10 to 20 mass% of a maleic acid-modified polyolefin, and further comprises a metal hydroxide and carbon black added in an amount of 150 to 220 mass parts per 100 mass parts of the base polymer, the metal hydroxide and the carbon black being added in a ratio of 15:1 to 100:1 (metal hydroxide:carbon black), and the composition is crosslinked.

[0007] Patent Document 5 describes an in-vehicle electric wire / cable that has high heat resistance and flexibility, as well as excellent mechanical strength, abrasion resistance, and flame retardancy. This in-vehicle electric wire / cable has as its covering material a resin composition obtained by adding a combination of two specific antioxidants and a specific brominated flame retardant to an ethylene-based copolymer containing an ethylene-ethyl acrylate copolymer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-111920 [Patent Document 2] International Publication No. 2018 / 074233 [Patent Document 3] International Publication No. 2016 / 175076 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-038869 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-164114 Summary of the Invention [Problem to be solved by the invention]

[0009] When polyethylene and ethylene-vinyl acetate copolymer are used in combination as the base resin for the insulation material of electric wires, the ethylene-vinyl acetate copolymer incorporates a vinyl acetate (polar molecule) component into its polymer structure, so increasing the proportion of ethylene-vinyl acetate copolymer in the base resin improves adhesion to metals. This improves adhesion to conductors and allows for greater flexibility in handling and processing of insulated electric wires. However, improving adhesion to metal increases contact wear with the metal die during extrusion, increasing friction between the inside of the die and the coating material. As a result, die scum (rubbing debris) is more likely to form at the tip of the die. The accumulation of die scum can impair the appearance of the finished product (surface roughness) and manufacturability (yield due to bumps and protrusions). Furthermore, if the adhesive strength between the resin coating and the conductor is too high, the conductor strands may be pulled out irregularly or may break during the wire stripping process, resulting in poor wire stripping performance. Conversely, if the adhesive strength between the resin coating and the conductor is too low, shrinkage back occurs after wire stripping due to the shrinkage of the insulator, exposing the conductor at the end, making the exposed area susceptible to moisture and other contaminants, which may cause electrical problems.

[0010] On the other hand, increasing the proportion of polyethylene in the base resin can improve the abrasion resistance of the wire. However, polyethylene has a high degree of crystallinity, and this degree increases as the density increases. Therefore, increasing the proportion of polyethylene in the base resin or using high-density polyethylene makes it easier for other low-molecular-weight components to migrate to the surface (bleeding, blooming). This increases the risk of contamination on the production line.

[0011] In view of the above circumstances, an object of the present invention is to provide a resin composition that, when used to form an insulating coating (resin coating layer) for an insulated wire, can improve the ability to form a coating around a conductor, give the resulting insulated wire an excellent appearance, and achieve desired excellent properties suitable for the insulated wire, including flame retardancy and mechanical properties. Another object of the present invention is to provide a resin coating material using the resin composition, an insulated wire whose insulating coating comprises the resin coating, an automotive wire harness including the insulated wire, and a method for producing an insulated wire for use in an automotive wire harness. [Means for solving the problem]

[0012] As a result of investigations aimed at solving the above problems, the present inventors have found that by blending specific amounts of at least one of a thioether compound and a fluororubber in a resin composition for an insulating coating material (resin coating material) that uses a combination of a low-density polyethylene resin and an ethylene-vinyl acetate copolymer as the base resin, foreign matter such as resin residue (so-called "die resin") is less likely to be generated at the extrusion die outlet during the formation of an insulating coating by extrusion coating, bleeding is suppressed in subsequent processes, and contamination of the production line (guide pulleys, etc.) is prevented, and the resulting resin coating material also has excellent flame retardancy and mechanical strength. Based on these findings, further investigations led to the completion of the present invention.

[0013] That is, the above problems were solved by the following means. <1> The composition contains the following components (A) and (B) and at least one of the following components (C) and (D), (A) low-density polyethylene resin, (B) ethylene-vinyl acetate copolymer resin, (C) thioether compounds, (D) fluororubber, the content of component (A) is 5 to 40 parts by mass and the content of component (B) is 60 to 95 parts by mass, relative to 100 parts by mass of the total content of components (A) and (B); and the total content of components (C) and (D) is 0.05 to 1 part by mass, relative to 100 parts by mass of the total content of components (A) and (B); A resin composition, wherein the proportion of vinyl acetate in component (B) is 40 mass % or less. <2> The proportion of vinyl acetate in the component (B) is 7% by mass or more. <1> The resin composition according to claim 1. <3> the content of the component (C) is 0.7 parts by mass or less and the content of the component (D) is 1 part by mass or less, relative to 100 parts by mass of the total content of the components (A) and (B); <1> or <2> The resin composition according to claim 1. <4> The content of the component (A) is more than 20 parts by mass and 40 parts by mass or less, the content of the component (B) is 60 parts by mass or more and less than 80 parts by mass, and the content of the component (C) is 0.5 parts by mass or less relative to 100 parts by mass of the total content of the components (A) and (B), <1> ~ <3> The resin composition according to any one of the preceding claims. <5> In a total of 100 parts by mass of the components (A) and (B), the content of the component (A) is 5 parts by mass or more and 20 parts by mass or less, the content of the component (B) is 80 parts by mass or more and 95 parts by mass or less, and the total content of the components (C) and (D) is 0.5 to 1 part by mass relative to a total of 100 parts by mass of the components (A) and (B), <1> ~ <3> The resin composition according to any one of the preceding claims. <6> The VA value calculated by the following formula is 15 or more, and the total content of the components (C) and (D) is 0.5 to 1 part by mass relative to 100 parts by mass of the total content of the components (A) and (B), <1> ~ <5> The resin composition according to any one of the preceding claims. VA value = [content (parts by mass) of component (B) in 100 parts by mass of the total content of components (A) and (B)] × [proportion (% by mass) of vinyl acetate in component (B)] / 100 <7> The resin composition contains at least one of a flame retardant, an antioxidant, a processing aid, and a crosslinking aid in addition to the components (A) to (D). <1> ~ <6> The resin composition according to any one of the preceding claims. <8> The above-mentioned wire harness for automobiles <1> ~ <7> The resin composition according to any one of the preceding claims. <9> The aforementioned <1> ~ <8> 2. A resin coating material obtained by crosslinking the resin composition according to any one of the preceding items. <10> The insulating film is <9> An insulated wire having the resin coating material according to claim 1. <11> The aforementioned <10> 10. An automotive wire harness comprising the insulated wire according to claim 9. <12> On the conductor, <1> ~ <8> 1. A method for producing an insulated wire used in an automobile wiring harness, comprising the steps of extrusion coating the resin composition according to any one of the above items 1 to 4 to form a layer of the resin composition, and irradiating the layer of the resin composition with an electron beam of 80 to 250 kGy.

[0014] In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after it as the lower and upper limits. [Effects of the Invention]

[0015] When used to form an insulating coating (resin coating layer) for an insulated electric wire, the resin composition of the present invention can improve the ability to form a coating around the conductor, resulting in an insulated electric wire with excellent appearance and achieving the desired excellent flame retardancy and mechanical properties suitable for the insulated electric wire. When used as a constituent material for the insulating coating of an insulated electric wire, the resin coating material of the present invention contributes to improving the productivity of the insulated electric wire and also enables the production of an insulated electric wire with excellent appearance and the desired excellent flame retardancy and mechanical properties. The automotive wire harness of the present invention has an insulated electric wire that constitutes the automotive wire harness, and the insulated electric wire has the above-described resin coating material in its insulating coating, resulting in excellent productivity, excellent appearance, and excellent flame retardancy and mechanical properties. The method for producing an insulated electric wire for use in an automotive wire harness of the present invention can produce an insulated electric wire with the above-described excellent properties or advantages while suppressing contamination of the production line (guide pulleys, etc.). DETAILED DESCRIPTION OF THE INVENTION

[0016] [Resin composition] The resin composition of the present invention contains (A) a low-density polyethylene resin (also referred to as component (A)), (B) an ethylene-vinyl acetate copolymer resin (also referred to as component (B)), and at least one of a thioether compound (C) (also referred to as component (C)) and a fluororubber (D) (also referred to as component (D)). Components (A) to (D) and the optional components described below may each be used alone or in combination of two or more. The components contained in the resin composition of the present invention will be described below.

[0017] <(A) Low-density polyethylene resin> The resin composition of the present invention contains (A) a low-density polyethylene resin as a resin component constituting the base resin. In the present invention, the term "low-density polyethylene resin" refers to a polyethylene resin having a density of 0.929 g / cm. 3 It refers to the following polyethylene resins. For example, "low density polyethylene (LDPE)" and "very low density polyethylene (VLDPE)" are included. The low-density polyethylene resin used in the present invention preferably has a density range of 0.870 to 0.929 g / cm 3 and more preferably, the density range is 0.910 to 0.929 cm 3 The density of polyethylene can be determined in accordance with JIS K 7112.

[0018] The content of component (A) in the resin composition of the present invention is 5 to 40 parts by mass per 100 parts by mass of the total content of components (A) and (B). From the viewpoint of adjusting the adhesion between the resin coating material and the conductor to an appropriate level, the content of component (A) per 100 parts by mass of the total content of components (A) and (B) is preferably 10 to 35 parts by mass, more preferably 15 to 30 parts by mass. Furthermore, increasing the proportion of (B) ethylene-vinyl acetate copolymer in the resin composition can improve the flexibility and flame retardancy of the coating material. Particularly in the field of automotive applications, further improvements in the flexibility of coating materials are required in view of the increasing current capacity, ease of wiring management, and space savings of hybrid and electric vehicles that have been developed in recent years. Therefore, from the viewpoint of imparting flexibility to an insulated electric wire formed by coating a conductor with the resin composition, the component (A) is preferably contained in an amount of 5 to 20 parts by mass, more preferably 5 to 10 parts by mass, per 100 parts by mass of the total content of components (A) and (B). Furthermore, from the viewpoint of imparting abrasion resistance to an insulated electric wire formed by coating a conductor with the resin composition, the component (A) is preferably contained in an amount of 20 to 40 parts by mass, more preferably 30 to 40 parts by mass.

[0019] The melt flow rate (MFR) of the component (A) used in the present invention is preferably 0.1 to 20 g / 10 min (load 2.16 kg, temperature 190° C.), more preferably 0.2 to 10 g / 10 min. By setting the melt flow rate of component (A) within the above preferred range, the load on the kneading equipment and extruder can be further reduced during preparation of the resin composition and during production of the insulated wire or wire harness, and the dispersibility of each component in the resin composition can also be further improved. The melt flow rate (MFR) can be measured using an extrusion type plastometer (melt indexer) specified in JIS K6760 as a testing machine, by a method conforming to JIS K7210.

[0020] Furthermore, the component (A) used in the present invention may be, for example, a high-pressure radical (high-pressure) low-density polyethylene or a metallocene-catalyzed linear low-density polyethylene. For the polyethylene, see, for example, the description in Japanese Patent Application No. 2016-072380. The component (A) used in the present invention may also be a modified polyethylene (for example, an acid-modified polyethylene).

[0021] The polyethylene used in the present invention can be synthesized by a conventional method, or a commercially available product can be used. Specific examples of commercially available products include Petrothene 180R, Petrothene 170R, and Petrothene 173R manufactured by Tosoh Corporation, Sumikathene F218-0, Sumikathene F200, and Sumikathene G401 manufactured by Sumitomo Chemical Co., Ltd., Novatec LF443, Novatec LF280H, and Novatec LF448K1 manufactured by Japan Polyethylene Co., Ltd., NUC-9060 and ENGAGE-8100 manufactured by NUC Corporation, and NUCG-5130 manufactured by Dow Estramers (all trade names).

[0022] <(B) Ethylene-vinyl acetate copolymer resin> The resin composition of the present invention contains component (A) and (B) an ethylene-vinyl acetate copolymer resin as resin components constituting the base resin. In the resin composition of the present invention, the content of component (B) is 60 to 95 parts by mass per 100 parts by mass of the total content of components (A) and (B). From the viewpoint of improving the adhesion between the resin coating material and the conductor, the content of component (B) is preferably 65 to 90 parts by mass, more preferably 70 to 85 parts by mass. In particular, from the viewpoint of imparting flexibility to an insulated wire obtained by coating a conductor with the resin composition, the content of component (B) is preferably 80 to 95 parts by mass, more preferably 90 to 95 parts by mass, per 100 parts by mass of the total content of components (A) and (B). Furthermore, from the viewpoint of imparting abrasion resistance to an insulated wire obtained by coating a conductor with the resin composition, the content of component (B) is preferably 60 to 80 parts by mass, more preferably 60 to 70 parts by mass. The polymerization form of the ethylene-vinyl acetate copolymer used in the present invention may be any of block, random and graft.

[0023] The content of the vinyl acetate component constituting component (B) is 40% by mass or less. From the viewpoint of adjusting the adhesion between the resin coating material and the conductor to an appropriate level, the content of the vinyl acetate component is preferably 30% by mass or less, and more preferably 20% by mass or less. From the same viewpoint as above, the content of the vinyl acetate component is preferably 7% by mass or more, and more preferably 9% by mass or more. By keeping the content of the vinyl acetate component within the above range, the resin coating material produced using the resin composition of the present invention can acquire sufficient mechanical properties such as tensile strength and tensile elongation, and further improve the flame retardancy of the insulated wire.

[0024] Furthermore, from the viewpoint of imparting the desired adhesive strength between the resin coating material and the conductor, the VA value calculated by the following formula is preferably 7 to 30, more preferably 8 to 28, even more preferably 10 to 25, and also preferably 10 to 20. VA value = [content (parts by mass) of component (B) in 100 parts by mass of the total content of components (A) and (B)] × [proportion (% by mass) of vinyl acetate in component (B)] / 100

[0025] The melt flow rate (MFR) of the component (B) used in the present invention is preferably 0.1 to 10 g / 10 min (load 2.16 kg, temperature 190° C.), more preferably 0.5 to 5 g / 10 min. By setting the melt flow rate of component (B) within the above preferred range, the load on the kneading equipment and extruder can be further reduced during preparation of the resin composition and production of the insulated wire or wire harness, and the dispersibility of each component in the resin composition can be further improved. The melt flow rate (MFR) can be determined in the same manner as described above.

[0026] The ethylene-vinyl acetate copolymer (B) used in the present invention can be synthesized by a conventional method, or a commercially available product may be used, such as Evaflex V5961, Evaflex V5274, and Evaflex EV170 (all trade names) manufactured by DuPont-Mitsui Polychemicals Co., Ltd.

[0027] The total content of the components (A) and (B) in the resin composition of the present invention is preferably 7 to 80 mass %, more preferably 10 to 75 mass %, and even more preferably 20 to 70 mass %, from the viewpoints of improving the adhesion between the resin coating material and the conductor and imparting flexibility and abrasion resistance. The total content of the components (A) and (B) in the resin composition is also preferably 30 to 80 mass %, also preferably 40 to 75 mass parts, and also preferably 50 to 75 mass parts.

[0028] <(C) Thioether compound and (D) fluororubber> The resin composition of the present invention contains a specific amount of at least one of (C) a thioether compound and (D) a fluororubber, which allows the adhesion between the conductor and the resin coating material to be controlled when the resin composition is applied around the conductor, thereby improving film formability during coating (when manufacturing the electric wire) and processability of the electric wire after coating. In the resin composition of the present invention, the total content of components (C) and (D) is 0.05 to 1 part by mass relative to 100 parts by mass of the total content of components (A) and (B). From the viewpoint of adjusting the adhesion between the resin coating material and the conductor to an appropriate level, the total content of components (C) and (D) is preferably 0.1 to 1.0 part by mass, but may also be 0.1 to 0.8 part by mass, or may be 0.1 to 0.5 part by mass. In the present invention, the "total content of components (C) and (D)" means the content of either component (C) or (D) contained in the resin composition when the resin composition contains only one of the components, and means the total content of components (C) and (D) when the resin composition contains both components (C) and (D). The resin composition of the present invention preferably contains only one of components (C) and (D). When the resin composition of the present invention contains component (C) but does not contain component (D), the content of component (C) is 0.05 to 1 part by mass per 100 parts by mass of the total content of components (A) and (B). In this case, the content of component (C) is preferably 0.1 to 1 part by mass per 100 parts by mass of the total content of components (A) and (B). When the resin composition of the present invention contains component (D) but does not contain component (C), the content of component (D) is 0.05 to 1 part by mass per 100 parts by mass of the total content of components (A) and (B). In this case, the content of component (D) is preferably 0.1 to 1 part by mass per 100 parts by mass of the total content of components (A) and (B).

[0029] ((C) Thioether Compounds) Component (C) that can be used in the present invention is not particularly limited as long as it is a compound having a thioether bond, but it is preferable that the melting point of the compound be 60° C. or less. Examples of such thioether compounds include thioether-based antioxidants (antioxidants having a thioether bond) that are used as antioxidants for wire coating materials. Examples include dilauryl 3,3'-thiodipropionate (melting point: 40 to 42°C), dimyristyl 3,3'-thiodipropionate (melting point: 48 to 53°C), distearyl 3,3'-thiodipropionate (melting point: 65 to 67°C), and 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate] (melting point: 46 to 52°C, also known as 2,2-bis[[3-(dodecylthio)-1-oxopropyloxy]methyl]-1,3-propanediyl bis[3-(dodecylthio)propionic acid]). Among these, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate] is preferred from the viewpoint of long-term thermal stability and improved resistance to extraction. The resin composition of the present invention may contain a commercially available thioether antioxidant, such as Adekastab AO-412S (trade name, manufactured by ADEKA Corporation).

[0030] ((D) Fluorine rubber) Component (D) that can be used in the present invention includes homopolymer or copolymer rubbers containing fluorine atoms in the main chain or side chain. Fluorine rubbers are usually obtained by (co)polymerizing fluorine atom-containing monomers. Examples of such component (D) include, but are not limited to, copolymer rubbers of fluorine-containing monomers such as perfluorohydrocarbons such as tetrafluoroethylene and hexafluoropropylene, and partially fluorinated hydrocarbons (e.g., vinylidene fluoride), as well as copolymer rubbers of these perfluorohydrocarbons and / or fluorine-containing monomers with hydrocarbons such as ethylene and / or propylene. Specific examples include tetrafluoroethylene-propylene copolymer rubber (FEPM), tetrafluoroethylene-fluorinated (e.g., hexafluoro)propylene copolymer rubber, tetrafluoroethylene-perfluorovinyl ether copolymer rubber (FFKM), and vinylidene fluoride rubber (FKM, e.g., vinylidene fluoride-hexafluoropropylene copolymer rubber). Further examples include the above-mentioned copolymer rubbers of perfluorohydrocarbons and / or fluorine-containing monomers with chloroprene and / or chlorosulfonated polyethylene. Among these fluororubbers, tetrafluoroethylene-propylene copolymer rubber and vinylidene fluoride-hexafluoropropylene copolymer rubber are preferred, and tetrafluoroethylene-propylene copolymer rubber is more preferred. The resin composition of the present invention may contain commercially available fluororubber, such as Viton FreeFlow 10 (trade name, manufactured by Chemours).

[0031] In particular, when the content of component (A) is 5 to 20 parts by mass and the content of component (B) is 80 to 95 parts by mass, the total content of components (C) and (D) in the resin composition is preferably 0.5 to 1 part by mass, more preferably 0.7 to 1 part by mass, per 100 parts by mass of the total content of components (A) and (B), in order to suppress the adhesion between a resin coating material made of the resin composition and a conductor. In this case, it is preferable that the resin composition contains only one of components (C) and (D). Furthermore, when the resin composition contains more than 20 parts by mass and not more than 40 parts by mass of component (A) and (B) in a total of 100 parts by mass, and the resin composition contains at least 60 parts by mass and less than 80 parts by mass of component (B), the resin composition contains preferably not more than 1 part by mass, more preferably not more than 0.8 parts by mass, even more preferably not more than 0.6 parts by mass, and even more preferably not more than 0.5 parts by mass of component (D) in a total of 100 parts by mass of components (A) and (B), from the viewpoint of suppressing adhesion between a resin coating material made of the resin composition and a conductor and suppressing bleeding and blooming (hereinafter collectively referred to simply as "bleeding"). In this case, the resin composition preferably does not contain component (C) and contains at least 0.3 parts by mass of component (D). Similarly, when the content of component (A) is more than 20 parts by mass and not more than 40 parts by mass and the content of component (B) is 60 parts by mass or more and less than 80 parts by mass, the content of component (C) is preferably not more than 0.7 parts by mass, more preferably not more than 0.5 parts by mass, and even more preferably not more than 0.3 parts by mass, based on 100 parts by mass of the total content of components (A) and (B) in the resin composition. In this case, it is also preferable that the composition does not contain component (D) and contains 0.1 part by mass or more of component (C).

[0032] When the VA value is 15 or more, the total content of components (C) and (D) contained in the resin composition is preferably 0.5 to 1 part by mass, more preferably 0.7 to 1 part by mass, per 100 parts by mass of the total content of components (A) and (B), from the viewpoint of suppressing the adhesive strength between the resin coating material made of the resin composition and the conductor. In this case, the VA value is preferably 30 or less, more preferably 28 or less.

[0033] <Other ingredients> In addition to the above components, the resin composition of the present invention may contain other components such as the following flame retardants, antioxidants, processing aids, and crosslinking aids, as long as the effects of the present invention are not impaired.

[0034] <Flame retardant> The present invention can contain a flame retardant to the extent that the effects of the present invention are not impaired. Examples of such flame retardants include bromine-based flame retardants and antimony-based flame retardants. The present invention preferably contains at least one of a bromine-based flame retardant or an antimony-based flame retardant, and more preferably contains both a bromine-based flame retardant and an antimony-based flame retardant. Furthermore, the mixing ratio of the bromine-based flame retardant and the antimony-based flame retardant is preferably within a range such that the molar ratio of bromine element to antimony element contained in the resin composition is 2 to 5 times the molar amount of bromine element. In other words, it is preferable to contain a bromine-based flame retardant whose molar amount is 2 to 5 times the molar amount of antimony-based flame retardant. When the resin composition of the present invention contains a flame retardant, it preferably contains a total amount of 33 to 45 parts by mass of the flame retardant per 100 parts by mass of the total content of components (A) and (B).

[0035] (Brominated flame retardants) The brominated flame retardant used in the present invention is preferably a bromine-containing compound. That is, the resin composition of the present invention preferably contains a bromine-containing compound as a flame retardant. Examples of brominated flame retardants that can be used include brominated N,N'-ethylenebisphthalimide or compounds derived therefrom (collectively referred to as "brominated N,N'-ethylenebisphthalimide compounds"), N,N'-bis(bromophenyl)terephthalamide or compounds derived therefrom (collectively referred to as "N,N'-bis(bromophenyl)terephthalamide compounds"), brominated bisphenol or compounds derived therefrom (collectively referred to as "brominated bisphenol compounds"), and 1,2-bis(bromophenyl)alkanes and other organic bromine-containing flame retardants. Among these, for example, brominated N,N'-ethylenebisphthalimide and / or 1,2-bis(bromophenyl)ethane are preferably used. By using brominated N,N'-ethylenebisphthalimide and / or 1,2-bis(bromophenyl)alkyl, preferably 1,2-bis(pentabromophenyl)ethane, as a flame retardant, it is possible to form a resin coating material that hardly causes bleeding. The brominated flame retardant used in the resin composition of the present invention may be a commercially available brominated flame retardant, such as Cytex 8010 (trade name, manufactured by Albemarle).

[0036] When the resin composition of the present invention contains a brominated flame retardant, it preferably contains 15 to 35 parts by mass of the brominated flame retardant per 100 parts by mass of the total content of components (A) and (B).

[0037] (Antimony-based flame retardant) Examples of antimony-based flame retardants include antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate. Antimony reacts with chlorine (halogen), and the generated gas is thought to block oxygen, promoting the formation of a carbonized layer and trapping free radicals (stopping the pyrolysis chain reaction). Among these, in the present invention, it is preferable to add antimony trioxide from the viewpoint of forming a more stable carbonized layer. In the present invention, commercially available antimony trioxide may be used, for example, PATOX-C (trade name, manufactured by Nippon Seiko Co., Ltd.).

[0038] When the resin composition of the present invention contains an antimony-based flame retardant, it preferably contains 5 to 15 parts by mass of the antimony-based flame retardant per 100 parts by mass of the total content of components (A) and (B).

[0039] (Other flame retardants) The resin composition of the present invention may contain, in addition to the above-mentioned bromine-based flame retardant and antimony-based flame retardant, a flame retardant that can be commonly used in the insulating coating of an insulated electric wire. Examples of such flame retardants include metal hydroxides (hydroxide-based flame retardants) such as magnesium hydroxide and aluminum hydroxide. When the resin composition of the present invention contains a hydroxide-based flame retardant, its amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by mass of the total content of components (A) and (B).

[0040] <Antioxidants> The resin composition of the present invention may contain an antioxidant, such as a phenol compound (phenol-based antioxidant) or an imidazole compound (imidazole-based antioxidant). When the resin composition of the present invention contains an antioxidant, it preferably contains 2 to 6 parts by mass in total of the antioxidant per 100 parts by mass of the total content of components (A) and (B).

[0041] (phenolic antioxidant) Examples of the phenolic antioxidant that can be used in the resin composition of the present invention include triethylene glycol-bis(3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate), 1,6-hexanediol-bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), pentaerythrityl-tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, Examples include tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate and isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. Among these, from the viewpoint of imparting high heat resistance to automotive wire harnesses, those having two or more 3,5-di-t-butyl-4-hydroxyphenyl groups or 3,5-di-t-butyl-4-hydroxybenzyl groups are preferred, and tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate and pentaerythrityl-tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) are particularly preferred. In the present invention, commercially available phenolic antioxidants may be used, such as Irganox 1010 (trade name, manufactured by BASF).

[0042] When the resin composition of the present invention contains a phenolic antioxidant, it preferably contains 0.5 to 2 parts by mass of the phenolic antioxidant per 100 parts by mass of the total content of components (A) and (B).

[0043] (imidazole antioxidant) Examples of imidazole-based antioxidants that can be used in the resin composition of the present invention include 2-sulfanylbenzimidazole, 2-sulfanylmethylbenzimidazole, 4-sulfanylmethylbenzimidazole, 5-sulfanylmethylbenzimidazole, and zinc salts thereof, with 2-sulfanylbenzimidazole and its zinc salt being preferred. In the present invention, commercially available imidazole antioxidants may be used, such as Nocrac MBZ (trade name, manufactured by Ouchi Shinko Chemical Co., Ltd.).

[0044] When the resin composition of the present invention contains an imidazole-based antioxidant, it preferably contains 1 to 4 parts by mass of the imidazole-based antioxidant per 100 parts by mass of the total content of components (A) and (B).

[0045] <Processing aids> The resin composition of the present invention preferably contains a processing aid, and a preferred example of the processing aid is a metal soap (lubricant). Examples of metal soaps (lubricants) that can be used in the resin composition of the present invention include calcium stearate, zinc stearate, and magnesium stearate. In the present invention, commercially available metal soaps may be used, such as Shinaka Red ZS-101 (trade name, manufactured by Shinagawa Kako Co., Ltd.).

[0046] When the resin composition of the present invention contains a metal soap, it is preferable that the metal soap be contained in an amount of 0.5 to 2 parts by mass per 100 parts by mass of the total content of components (A) and (B).

[0047] <Crosslinking aid> The resin composition of the present invention preferably contains a crosslinking aid. Examples of the crosslinking aid include polyfunctional compounds, and preferred are compounds having two or more (preferably three or more, more preferably three to six) ethylenically unsaturated bonds (carbon-carbon double bonds) in the molecule. Specific examples of the crosslinking aid include (meth)acrylate compounds such as polypropylene glycol diacrylate and trimethylolpropane triacrylate, allyl compounds such as triallyl cyanurate, maleimide compounds, and divinyl compounds. In the present invention, a commercially available crosslinking aid may be used, for example, Ogmont T200 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). The resin composition of the present invention preferably contains 1 to 4 parts by mass of a crosslinking aid relative to 100 parts by mass of the total content of components (A) and (B).

[0048] <Additives> The resin composition of the present invention can contain various additives, such as copper inhibitors, ultraviolet absorbers, dispersants, plasticizers, fillers, and pigments, as needed, within the range that does not impair the effects of the present invention. Examples of such additives include zinc compounds. Specific examples of zinc compounds include zinc sulfide and zinc oxide.

[0049] [Method of producing resin composition] The resin composition of the present invention can be obtained by blending the above-mentioned components (A) to (D) and, if necessary, the above-mentioned optional components, and melt-kneading them in a commonly used kneading device such as a batch kneader, a roll, a kneader, a Banbury mixer, or the like, or a twin-screw extruder.

[0050] [Insulated wire] The insulated wire of the present invention has a layer made of a resin coating material obtained by crosslinking the resin composition of the present invention on the surface of a conductor (including a conductor bundle and a fiber core). The insulated wire of the present invention may have an intermediate layer or a shielding layer between the conductor and the layer made of the resin coating material.

[0051] When the cross-sectional area of ​​the insulated wire of the present invention is 2 sq (JIS standard) or less, from the viewpoint of imparting abrasion resistance to the insulated wire, it is preferable to incorporate a large amount of the polyethylene resin (component (A)) into the resin composition of the present invention, which is the coating material. Specifically, the content of component (A) is preferably 20 to 40 parts by mass, more preferably 30 to 40 parts by mass, per 100 parts by mass of the total content of components (A) and (B) in the resin composition of the present invention. Furthermore, when the content of component (A) in the base resin is within the above range, from the viewpoint of suppressing bleeding, it is preferable to limit the amount of the thioether compound (component (C)) and use the fluororubber (component (D)) as the main component to control the adhesion between the wire coating material and the conductor. Furthermore, when the cross-sectional area of ​​the insulated wire of the present invention is 3 sq or more, from the viewpoint of imparting flexibility to the insulated wire, it is preferable to blend a large amount of ethylene-vinyl acetate copolymer (B) into the resin composition of the present invention, which is a coating material. Specifically, the content of component (B) in the resin composition of the present invention is preferably 80 to 95 parts by mass, more preferably 90 to 95 parts by mass, per 100 parts by mass of the total content of components (A) and (B).

[0052] [Automotive Wire Harnesses] The automotive wiring harness of the present invention includes the insulated wire of the present invention. The resin composition of the present invention has excellent appearance, flame retardancy, and mechanical properties. Therefore, a wiring harness incorporating an insulated wire having a layer made of a resin coating material crosslinked from the resin composition of the present invention can be suitably used in automobiles. Hereinafter, the automotive wire harness may be simply referred to as a "wire harness."

[0053] [Manufacturing method for insulated wires used in automotive wiring harnesses] The insulated wire used in the automotive wiring harness of the present invention can be obtained by extrusion coating the resin composition of the present invention onto a conductor to form a resin composition layer, and then irradiating the resin composition layer with an electron beam of 80 to 250 kGy. This electron beam irradiation causes a crosslinking reaction in the resin composition layer, forming a resin coating material layer.

[0054] The conductor may be a single wire or a twisted wire, and may be a bare wire or a tin-plated or enamel-coated wire. Examples of metal materials for forming the conductor include soft copper, copper alloys, and aluminum. The thickness of the resin coating material formed around the conductor is not particularly limited, but is usually about 0.15 to 5 mm. The conductor diameter, conductor material, and coating layer thickness are not particularly limited and are determined appropriately depending on the purpose and application. The crosslinking reaction by electron beam irradiation can be carried out using conventional methods and conditions, and is not limited thereto. The electron beam irradiation conditions are preferably a dose of 50 to 450 kGy, more preferably 80 to 250 kGy, even more preferably 80 to 200 kGy, and particularly preferably 80 to 160 kGy. The acceleration voltage is preferably 300 to 3000 keV, more preferably 500 to 2500 keV. Furthermore, a multilayer structure may be used in which an intermediate layer or a shielding layer is provided between a conductor and a covering layer, or between covering layers.

[0055] The conditions for extrusion molding the resin composition of the present invention are not particularly limited as long as the resin composition of the present invention can be extruded. However, the extrusion temperature (at the head) is preferably 100 to 230°C, more preferably 120 to 200°C, in order to reduce the load on the extruder (extrusion molding machine) and ensure shape retention. Other conditions for extrusion molding can be appropriately set depending on the purpose. The screw configuration of the extruder is not particularly limited, and a normal full-flight screw, double-flight screw, tip double-flight screw, Maddock screw, etc. can be used.

[0056] The shape and material of the conductor may be any shape and material (copper, aluminum, etc.) that are generally used for insulated wires in automotive wire harnesses. The thickness of the resin coating layer is not particularly limited. When the resin composition of the present invention is used, there is an advantage that an insulated wire having excellent flexibility, hardness, degree of crosslinking, flame retardancy, cold resistance, and heat resistance can be obtained even if the thickness of the resin coating layer is thin. [Example]

[0057] The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited to these.

[0058] [Examples 1 to 8 and Comparative Examples 1 to 9] The materials used to prepare the resin compositions of Examples 1 to 8 and Comparative Examples 1 to 9 are shown in Tables 1 and 2 below. Details of the materials used are as follows. Note that (1) to (18) below correspond to (1) to (18) in Tables 1 and 2 below.

[0059] <Materials used> (Component (A): Polyethylene (PE) resin) (1): NUC-9060 (product name), manufactured by NUC, density 0.923g / cm 3 (2): NUCG-5130 (trade name), manufactured by Dow Elastomers, density 0.923 g / cm 3 (3): ENGAGE-8100 (product name), manufactured by NUC, density 0.870 g / cm 3 (4): HI-ZEX-5305E (product name), manufactured by Prime Polymer Co., Ltd., density 0.950 g / cm 3 (5): Adtex L6100M (product name), manufactured by Japan Polyolefins Co., Ltd., density 0.920 g / cm 3 , maleic acid modified

[0060] (Component (B): vinyl acetate copolymer resin) (6): Evaflex V5961 (trade name), manufactured by Mitsui DuPont Polychemicals, vinyl acetate content: 9% by mass (7): Evaflex V5274 (product name), manufactured by Mitsui DuPont Polychemicals Vinyl acetate content: 17% by mass (8): Evaflex EV170 (trade name), manufactured by Mitsui DuPont Polychemicals, vinyl acetate content: 33% by mass (9): Evaflex EV40LX (trade name), manufactured by Mitsui DuPont Polychemicals, vinyl acetate content: 41% by mass (10): Evaflex EV45LX (trade name), manufactured by Mitsui DuPont Polychemicals, vinyl acetate content: 46% by mass

[0061] (Component (C): Thioether compound) (11): 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate], Adeka Stab AO-412S (trade name), manufactured by ADEKA Corporation

[0062] (Component (D): Fluorine rubber) (12): Viton FreeFlow10 (product name), manufactured by Chemours

[0063] (Flame retardant) (13): 1,2-bis(pentabromophenyl)ethane, Cytex 8010 (trade name), manufactured by Albemarle (14): Antimony trioxide, PATOX-C (trade name), manufactured by Nihon Seiko Co., Ltd.

[0064] (antioxidant) (15): Pentaerythrityl tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), a phenolic antioxidant, Irganox 1010 (trade name), manufactured by BASF (16): Imidazole antioxidant, zinc salt of 2-sulfanylbenzimidazole, Nocrac MBZ (trade name), manufactured by Ouchi Shinko Chemical Co., Ltd.

[0065] (processing aids) (17): Zinc stearate, Sinaka Red ZS-101 (trade name), manufactured by Shinagawa Chemical Industry Co., Ltd.

[0066] (Crosslinking aid) (18): Trimethylolpropane trimethacrylate, Ogmont T200 (trade name), manufactured by Shin-Nakamura Chemical Co., Ltd.

[0067] <Production of Resin Composition Pellets> According to the compositions shown in Tables 1 and 2 below, the mixtures were melt-kneaded at 180°C using a 1.7 liter Banbury mixer, and the mixtures were discharged and granulated through an extruder to obtain resin composition pellets of Examples 1 to 8 and Comparative Examples 1 to 9.

[0068] <Insulated wire manufacturing> Each resin composition pellet obtained above was extrusion coated onto a conductor using an extruder set at a temperature of 130 to 190°C. The formed resin composition layer was subjected to a cross-linking reaction by electron beam irradiation. 2 An insulated wire was obtained, which had a 0.7 mm thick insulating coating around a copper conductor with a circular cross section (≒3 sq). The crosslinking by electron beam was carried out under the conditions of an acceleration voltage of 800 keV and a dose of 160 kGy.

[0069] [Performance evaluation] The insulated wires manufactured as described above were subjected to the following performance evaluations.

[0070] <Surface smoothness> The surface smoothness (extrusion appearance) of each insulated wire was measured as follows. Using a laser microscope (LASER MICROSCOPE VK-X250, manufactured by KEYENCE Corporation), the surface of each insulated wire was measured along its length under conditions of a stylus tip curvature radius of 2 μm and a static measuring force of 0.75 mN at the stylus average position. Each measurement was performed three times (N=3), and the average value was taken as the arithmetic mean roughness Ra (μm). The calculated arithmetic mean roughness Ra was evaluated according to the following criteria. Evaluations A and B were considered acceptable. -Evaluation criteria- A: Ra is less than 2 μm B: Ra is 2 μm or more and less than 3 μm C: Ra is 3 μm or more

[0071] <Extrusion processability> After 5,000 m of extrusion molding onto the conductor under the conditions described above, the resin residue (die deposits and pitting residue) accumulated at the extrusion nozzle and the resin residue adhering to the insulated wire were evaluated according to the following criteria. Evaluations of A and B were deemed acceptable. The resin residue adhering to the insulated wire obtained by extrusion molding was removed sequentially using an air gun. The air gun used (product name: AG45, manufactured by Kurita Manufacturing Co., Ltd.) had a tip diameter of φ2.0 and an air pressure of 0.5 MPa. -Evaluation criteria- A: At the time of producing 5000m, no resin residue accumulated or adhered to the extrusion nozzle or insulated wire. B: At the time of producing 5000 m, resin residue accumulated at the extrusion outlet, but no resin residue was found adhering to the insulated wire after spraying with an air gun. C: At the time of producing 5000 m, resin residue accumulated at the extrusion outlet, and after being sprayed with an air gun, adhesion of resin residue to the insulated wire was observed.

[0072] <Breeding> An insulated wire precursor (length: 200 mm) extruded and coated with a resin composition was kept at 40°C for 1 hour before electron beam irradiation. A SUS304 round bar (φ20 × 300 mm, hereinafter also referred to as the "SUS bar") was moved back and forth 10 times (1 round trip: 200 mm × 2 times) in the longitudinal direction of the insulated wire precursor, perpendicular to the longitudinal direction of the insulated wire precursor, so as to be in contact with the surface of the insulated wire precursor (surface of the resin composition layer). The amount of deposits from each insulated wire adhering to the SUS304 round bar (adhesion of bleed components to the surface of the insulated wire) was evaluated. The adhesion of bleed components was visually observed, and a rating of A or B was considered acceptable. -Evaluation criteria- A: There was absolutely no adhesion of bleeding components. B: The adhesion area of ​​the bleeding component was less than half of the contact area between the insulated wire precursor and the SUS rod. C: The adhesion area of ​​the bleeding component was more than half of the contact area between the insulated wire precursor and the SUS rod.

[0073] <Adhesion> The adhesion strength between the insulating coating layer and the conductor was measured by a method conforming to the Society of Automotive Engineers of Japan standard JASO D618. The insulating coating was removed from the tip of a 75 mm insulated wire to expose the conductor, and the conductor was pulled at a pulling speed of 250 mm / min at room temperature (23°C). The maximum tensile force required for the resin coating to fall off the conductor was measured. The measurement results were evaluated according to the following criteria. A rating of A or B was considered a pass. -Evaluation criteria- A: Maximum tensile force is 10N or more and less than 40N B: Maximum tensile force is 40N or more and less than 80N C1: Maximum tensile force is less than 10N C2: Maximum tensile force is 80N or more

[0074] <Flame retardancy> An inclined flame test was conducted based on the International Organization for Standardization (ISO) 19642. A 600 mm long wire sample was cut from each insulated wire and supported at an angle of approximately 45 degrees to the horizontal. Using a 10 mm diameter Bunsen burner, the tip of a 50 mm reducing flame was applied to a point 500 ± 5 mm from the top of the sample for 30 seconds or until the conductor was exposed. The flame was then gently removed, and the afterflame time was measured and evaluated according to the following criteria. A rating of A or B was considered a pass. -Evaluation criteria- A: Afterflame time is less than 5 seconds B: Afterflame time is between 5 seconds and 30 seconds C: Afterflame time is 30 seconds or more

[0075] <Tensile properties> The coating material of the insulated wire was sampled and evaluated according to the following criteria based on Japanese Industrial Standard (JIS) K7161. The conductor was removed from each insulated wire to prepare a tubular sample, and the tensile strength (breaking strength, MPa) and breaking elongation (%) were measured with a gripping distance of 60 mm, a gauge length of 20 mm, and a pulling speed of 200 mm / min (room temperature, 23°C). The term "breaking elongation (%)" refers to the increase in the gauge length at the time the sample broke, expressed as a percentage of the initial gauge length. Therefore, a breaking elongation of 100% means that the gauge length had doubled. The measured tensile strength and breaking elongation were evaluated according to the following evaluation criteria. A rating of A or B was considered acceptable. -Evaluation criteria- A: Tensile strength of 20 MPa or more and elongation at break of 400% or more B: Tensile strength 15 MPa or more and less than 20 MPa, and / or elongation at break 300% or more and less than 400% C: Tensile strength less than 15 MPa and / or elongation at break less than 300%

[0076] The results obtained are summarized in the following Tables 1 and 2. The amounts blended in the tables below are in parts by mass (mass ratio).

[0077] TIFF0007813769000001.tif100170

[0078] TIFF0007813769000002.tif108170

[0079] The content of each component in the table is in parts by mass. Blank spaces and "-" indicate that the corresponding component is not included.

[0080] As can be seen from Table 2, the insulated wires using resin compositions that do not satisfy the requirements of the present invention failed in at least three evaluation items. In contrast, as is clear from Table 1, the insulated wires produced using the resin compositions of the present invention passed all evaluation criteria, demonstrating that the resin compositions of the present invention can be suitably used as resin coating layers for insulated wires.

[0081] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. The composition contains the following components (A) and (B) and at least one of the following components (C) and (D): (A) a low-density polyethylene resin; (B) ethylene-vinyl acetate copolymer resin, (C) a thioether compound, (D) fluororubber, the content of component (A) is 5 to 40 parts by mass and the content of component (B) is 60 to 95 parts by mass, based on 100 parts by mass of the total content of components (A) and (B); and the total content of components (C) and (D) is 0.05 to 1 part by mass, based on 100 parts by mass of the total content of components (A) and (B); An insulating resin composition, wherein the proportion of vinyl acetate in component (B) is 40 mass % or less.

2. 2. The insulating resin composition according to claim 1, wherein the proportion of the vinyl acetate component in the component (B) is 7% by mass or more.

3. 3. The insulating resin composition according to claim 1, wherein the content of component (C) is 0.7 parts by mass or less and the content of component (D) is 1 part by mass or less, relative to 100 parts by mass of the total content of components (A) and (B).

4. The insulating resin composition according to any one of claims 1 to 3, wherein, out of a total of 100 parts by mass of the components (A) and (B), the content of the component (A) is more than 20 parts by mass and 40 parts by mass or less, the content of the component (B) is 60 parts by mass or more and less than 80 parts by mass, and the content of the component (C) is 0.5 parts by mass or less relative to a total of 100 parts by mass of the components (A) and (B).

5. The insulating resin composition according to any one of claims 1 to 3, wherein, in a total of 100 parts by mass of the components (A) and (B), the content of the component (A) is 5 parts by mass or more and 20 parts by mass or less, the content of the component (B) is 80 parts by mass or more and 95 parts by mass or less, and the total content of the components (C) and (D) is 0.5 to 1 part by mass relative to a total of 100 parts by mass of the components (A) and (B).

6. 6. The insulating resin composition according to claim 1, wherein the VA value calculated by the following formula is 15 or more, and the total content of the components (C) and (D) is 0.5 to 1 part by mass relative to 100 parts by mass of the total content of the components (A) and (B). VA value = [content (parts by mass) of component (B) per 100 parts by mass of the total content of components (A) and (B)] × [proportion (% by mass) of vinyl acetate in component (B)] / 100

7. The insulating resin composition according to any one of claims 1 to 6, wherein the insulating resin composition contains at least one of a flame retardant, an antioxidant, a processing aid, and a crosslinking aid in addition to the components (A) to (D).

8. The insulating resin composition according to any one of claims 1 to 7, which is used for an automobile wire harness.

9. A resin coating material obtained by crosslinking the insulating resin composition according to any one of claims 1 to 8.

10. An insulated wire, wherein the insulating coating comprises the resin coating material according to claim 9.

11. A wiring harness for an automobile, comprising the insulated wire according to claim 10.

12. A method for producing an insulated wire used for an automotive wire harness, comprising the steps of extrusion coating the insulating resin composition according to any one of claims 1 to 8 onto a conductor to provide a layer of the resin composition, and irradiating the layer of the resin composition with an electron beam of 80 to 250 kGy.

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