Resin composition, resin-coated material, insulated wire, automotive wiring harness, and method for manufacturing an insulated wire for an automotive wiring harness

Abstract

A resin composition contains the following components (A) and (B), and contains at least one of the following components (C) and (D). (A) Low-density polyethylene resin, (B) ethylene-vinyl acetate copolymer resin, (C) thioether compound, (D) fluororubber. In 100 parts by mass of the total content of components (A) and (B), 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; with respect to 100 parts by mass of the total content of components (A) and (B), the total content of components (C) and (D) is 0.05 to 1 part by mass, and the proportion of the vinyl acetate component in component (B) is 40% by mass or less.

Description

Technical Field

[0001] The present invention relates to a resin composition, a resin-coated material, an insulated wire, an automotive wiring harness, and a method for manufacturing an insulated wire for an automotive wiring harness. Background Art

[0002] Insulated wires having flame retardancy are widely used in various household appliances, OA equipment, etc. In addition, insulated wires used in automobiles and the like are also required to have various properties such as flame retardancy, heat resistance, flexibility (flexibility), and mechanical properties. So far, many resin compositions for insulated wires that achieve flame retardancy, heat resistance, flexibility (flexibility), and mechanical properties through the coated material used as a conductor have been studied and reported.

[0003] As a resin composition constituting an insulated wire having such desired properties, resins such as polyethylene or ethylene-vinyl acetate copolymer are widely used.

[0004] For example, Patent Document 1 describes the following: 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 is used as a coated material for a conductor, and by crosslinking it, a flame-retardant wire having excellent flame retardancy, water resistance, and oil resistance is obtained.

[0005] Patent Document 2 describes a resin composition that, when used as a coated material for a conductor, can obtain an insulated wire having an insulating layer with excellent flexibility, oil resistance, and mechanical strength. The resin composition contains a copolymer of an unsaturated hydrocarbon having 4 or more carbon atoms and ethylene, a copolymer of an acrylate and ethylene, or a copolymer of a methacrylate and ethylene, a flame retardant, and a crosslinking aid, each in a specific amount and within a specific density range.

[0006] Patent Document 3 describes a halogen-free flame-retardant resin composition for forming an insulating coating of an insulated wire. The insulated wire has excellent flame retardancy, heat resistance, cold resistance (low-temperature characteristics), and oil resistance, and also has excellent mechanical strengths such as tensile mechanical properties and abrasion resistance, and these properties are balanced at a high level. In this resin composition, per 100 parts by mass of the polyolefin resin, 100 parts by mass or more and 250 parts by mass or less of a metal hydroxide are contained, and 1% by mass or more and 20% by mass or less of a silicone oil having a viscosity of 3000 mPa·s or less at 25°C is contained; the above polyolefin resin contains: 30% by mass or more and 85% by mass or less of polyethylene having a melting point (Tm) of 120°C or more and 130°C or less and a density of 0.925 or more and 0.945 or less based on the DSC method, 10% by mass or more and 60% by mass or less of an ethylene-vinyl acetate copolymer (EVA), and 5% by mass or more and 30% by mass or less of a maleic anhydride-modified ethylene α-olefin copolymer having a melting point of 60°C or less based on the DSC method.

[0007] Patent Document 4 describes an insulated wire and a cable using a halogen-free flame-retardant resin composition having flame retardancy and excellent oil / fuel resistance and impact resistance. In this halogen-free flame-retardant resin composition, 60 to 70% by mass of linear low-density polyethylene, 10% by mass or more of an ethylene-vinyl acetate copolymer having a melt flow rate (MFR) of 100 or more, and 10 to 20% by mass of a maleic acid-modified polyolefin are contained as base polymers. In addition, it is composed of a metal hydroxide added in a proportion of 150 to 220 parts by mass relative to 100 parts by mass of the above base polymers and carbon black, and the addition ratio of the above metal hydroxide and the above carbon black (metal hydroxide: carbon black) is 15:1 to 100:1, and it is crosslinked.

[0008] Patent Document 5 describes an in-vehicle wire / cable having high heat resistance and flexibility, and excellent mechanical strength, abrasion resistance, and flame retardancy. This in-vehicle wire / cable has a resin composition as a coating material, and the resin composition is obtained by adding specific two kinds of antioxidants and a specific bromine-based flame retardant to an ethylene-based copolymer containing an ethylene-ethyl acrylate copolymer in combination.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-111920

[0012] Patent Document 2: International Publication No. 2018 / 074233 Pamphlet

[0013] Patent Document 3: International Publication No. 2016 / 175076 Pamphlet

[0014] Patent Document 4: Japanese Patent Application Laid-Open No. 2015-038869

[0015] Patent Document 5: Japanese Patent Application Laid-Open No. 2015-164114 Summary of the Invention

[0016] Problems to be Solved by the Invention

[0017] As a base resin for a coating material constituting an electric wire, when polyethylene and ethylene-vinyl acetate copolymer are used in combination, since the ethylene-vinyl acetate copolymer introduces a vinyl acetate (polar molecule) component into the polymer structure, the adhesion to metal is improved by increasing the proportion of the ethylene-vinyl acetate copolymer in the base resin. Therefore, the adhesion to the conductor can be improved, and the freedom in the use and processing of the insulated electric wire can be enhanced.

[0018] However, the improvement in the adhesion to metal increases the contact wear with the metal die during extrusion processing and increases the friction between the inside of the die and the coating material. As a result, it is easy to generate eye discharge-like accumulations (abrasion residues) at the tip of the die. If the eye discharge-like accumulations (die residues) accumulate, it may damage the appearance of the manufactured product (surface roughness) and the manufacturability (yield rate due to nodules or protrusions, etc.).

[0019] In addition, if the adhesion between the resin coating material and the conductor is high, in the wire stripping process, the strands of the conductor will be irregularly pulled out or the strands will break, resulting in a decrease in the stripability. On the contrary, if the adhesion between the resin coating material and the conductor is low, after wire stripping, a shrink back phenomenon will occur as the insulator shrinks, and the conductor at the end portion will be exposed. Moisture and the like can easily penetrate into the exposed portion, which may cause electrical failures.

[0020] On the other hand, increasing the proportion of polyethylene in the base resin can improve the abrasion resistance of the electric wire. On the one hand, polyethylene has a large crystallinity, and the higher the density, the larger the crystallinity. Therefore, if the proportion of polyethylene in the base resin is increased or high-density polyethylene is used, other low-molecular components become more likely to migrate to the surface layer (bleed-out, blooming). Therefore, the risk of contamination of the production line increases.

[0021] In view of the above situation, the object of the present invention is to provide a resin composition which, when used to form an insulating film (resin coating layer) of an insulated wire, can improve the film-forming property around the conductor, can make the obtained insulated wire have an excellent appearance, and can also achieve excellent properties desired for insulated wires in terms of flame retardancy and mechanical properties. Another object of the present invention is to provide a resin coating material using the above resin composition, an insulated wire having an insulating film of the resin coating material, an automotive wire harness having the insulated wire, and a method for manufacturing an insulated wire for an automotive wire harness.

[0022] Means for Solving the Problem

[0023] The inventors of the present invention conducted research to solve the above problems and found that in a resin composition for an insulating coating material (resin coating material) that combines low-density polyethylene resin and ethylene-vinyl acetate copolymer as base resins, by mixing at least one of a thioether compound and fluororubber in a specific amount, when forming an insulating film by extrusion coating, it is difficult to generate foreign matters such as resin residues (substances so-called "eye discharge-like build-up") at the extrusion port of the extrusion die, and it is also possible to suppress overflow in subsequent processes to prevent contamination of the production line (guide wheels, etc.). In addition, the obtained resin coating material also has excellent flame retardancy and mechanical strength. The present invention was completed through further repeated research based on these technical ideas.

[0024] That is, the above problems are solved by the following means.

[0025] <1>

[0026] A resin composition containing the following components (A) and (B), and containing at least one of the following components (C) and (D),

[0027] (A) Low-density polyethylene resin,

[0028] (B) Ethylene-vinyl acetate copolymer resin,

[0029] (C) Thioether compound,

[0030] (D) Fluororubber,

[0031] In 100 parts by mass of the total content of components (A) and (B), 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), the total content of components (C) and (D) is 0.05 to 1 part by mass.

[0032] The proportion of the vinyl acetate component in component (B) is 40% by mass or less.

[0033] <2>

[0034] The resin composition as described in <1> above, wherein the proportion of the vinyl acetate component in the component (B) is 7% by mass or more.

[0035] <3>

[0036] The resin composition as described in <1> or <2> above, wherein, based on 100 parts by mass of the total content of the components (A) and (B), the content of the component (C) is 0.7 part by mass or less, and the content of the component (D) is 1 part by mass or less.

[0037] <4>

[0038] The resin composition as described in any one of <1> to <3> above, wherein, in 100 parts by mass of the total content 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, and the content of the component (B) is 60 parts by mass or more and less than 80 parts by mass; based on 100 parts by mass of the total content of the components (A) and (B), the content of the component (C) is 0.5 part by mass or less.

[0039] <5>

[0040] The resin composition as described in any one of <1> to <3> above, wherein, in 100 parts by mass of the total content 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, and the content of the component (B) is 80 parts by mass or more and 95 parts by mass or less; based on 100 parts by mass of the total content of the components (A) and (B), the total content of the components (C) and (D) is 0.5 to 1 part by mass.

[0041] <6>

[0042] The resin composition as described in any one of <1> to <5> above, wherein the VA value calculated by the following formula is 15 or more, and based on 100 parts by mass of the total content of the components (A) and (B), the total content of the components (C) and (D) is 0.5 to 1 part by mass.

[0043] VA value = [content of component (B) (parts by mass) in 100 parts by mass of the total content of components (A) and (B)] × [proportion of vinyl acetate component in component (B) (% by mass)] / 100

[0044] <7>

[0045] The resin composition as described in any one of <1> to <6> above, wherein, in addition to containing the components (A) to (D), the resin composition further contains at least one of a flame retardant, an antioxidant, a processing aid, and a crosslinking aid.

[0046] <8>

[0047] The resin composition according to any one of <1> to <7> above is used for automotive wire harnesses.

[0048] <9>

[0049] A resin coating material obtained by crosslinking the resin composition according to any one of <1> to <8> above.

[0050] <10>

[0051] An insulated wire, wherein the insulating film has the resin coating material according to <9> above.

[0052] <11>

[0053] An automotive wire harness having the insulated wire according to <10> above.

[0054] <12>

[0055] A method for manufacturing an insulated wire for an automotive wire harness, comprising the following steps: extruding and coating the resin composition according to any one of <1> to <8> above on a conductor to form a layer of the resin composition, and irradiating the layer of the resin composition with electron beams of 80 to 250 kGy.

[0056] In the present invention, the numerical range indicated by "~" means a range including the numerical values described before and after as the lower limit value and the upper limit value.

[0057] Effects of the Invention

[0058] By forming the insulating film (resin coating material layer) of the insulated wire, the resin composition of the present invention can improve the film-forming property around the conductor, can make the obtained insulated wire have excellent appearance, and can also achieve excellent properties desired for insulated wires in terms of flame retardancy and mechanical properties. By using the resin coating material of the present invention as a constituent material of the insulating film of the insulated wire, it can contribute to the improvement of the productivity of the insulated wire. In addition, an insulated wire having excellent appearance and showing excellent properties desired in terms of flame retardancy and mechanical properties can be obtained. In the automotive wire harness of the present invention, the insulated wire constituting the automotive wire harness has the above resin coating material on its insulating film, has excellent productivity, excellent appearance, and excellent flame retardancy and mechanical properties. According to the method for manufacturing an insulated wire for an automotive wire harness of the present invention, contamination of the production line (such as guide wheels) can be suppressed, and an insulated wire having the above excellent properties or advantages can be obtained. Detailed Embodiments

[0059] [Resin Composition]

[0060] 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 contains at least one of a thioether compound (C) (also referred to as component (C)) and a fluororubber (D) (also referred to as component (D)).

[0061] Each of components (A) to (D) and any of the components described later can be used alone as each component, or two or more thereof can be used in combination.

[0062] Hereinafter, the components contained in the resin composition of the present invention will be described.

[0063] <(A) Low-density polyethylene resin>

[0064] 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 "low-density polyethylene resin" refers to a polyethylene resin having a density of 0.929 g / cm 3 as follows. For example, "low-density polyethylene (LDPE)", "ultra-low-density polyethylene (VLDPE)", etc. can be cited.

[0065] The preferred density range of the low-density polyethylene resin used in the present invention is 0.870 to 0.929 g / cm 3 , and the more preferred density range is 0.910 to 0.929 g / cm 3 . It should be noted that the density of polyethylene can be determined according to JIS K 7112.

[0066] The content of component (A) contained in the resin composition of the present invention is 5 to 40 parts by mass in 100 parts by mass of the total content of components (A) and (B). From the aspect of adjusting the adhesion between the resin coating material and the conductor to an appropriate level, the content of component (A) in 100 parts by mass of the total content of components (A) and (B) is preferably 10 to 35 parts by mass, and more preferably 15 to 30 parts by mass.

[0067] In addition, by increasing the proportion of the (B) ethylene-vinyl acetate copolymer contained in the resin composition, the flexibility and flame retardancy of the coating material can be improved. Especially in the field of automotive applications, in view of the increasing current in hybrid vehicles and electric vehicles developed in recent years, ease of wiring processing, and space saving, etc., further improvement in the flexibility of the coating material is required. Therefore, in terms of making the insulated wire formed by coating the conductor with this resin composition flexible, in 100 parts by mass of the total content of components (A) and (B), it is preferably to contain 5 to 20 parts by mass of component (A), and more preferably 5 to 10 parts by mass. In addition, in terms of imparting abrasion resistance to the insulated wire formed by coating the conductor with this resin composition, the content of the above-mentioned component (A) is preferably 20 to 40 parts by mass, and more preferably 30 to 40 parts by mass.

[0068] In addition, the melt flow rate (Melt Flow Rate; MFR) of component (A) used in the present invention is preferably 0.1 to 20 g / 10 minutes (load 2.16 kg, temperature 190 °C), and more preferably 0.2 to 10 g / 10 minutes.

[0069] By making the melt flow rate of component (A) within the above-mentioned preferred range, the load on the kneading machine or extruder can be further suppressed during the preparation of the resin composition, during the production of the insulated wire or the harness, and in addition, the dispersibility of each component in the resin composition can be further improved.

[0070] The melt flow rate (MFR) can be measured by the method according to JIS K7210 using an extrusion plastometer (melt flow index measuring instrument) specified in JIS K6760 as the test machine.

[0071] In addition, the component (A) used in the present invention can be, for example, low-density polyethylene by the high-pressure free radical method (high-pressure method), or metallocene-catalyzed linear low-density polyethylene. As this polyethylene, for example, the description in Japanese Patent Application No. 2016-072380 can be referred to. The component (A) used in the present invention can be a modified product of polyethylene (for example, an acid-modified product).

[0072] The polyethylene used in the present invention can be synthesized by a conventional method or commercially available products can be used. Specific examples of commercially available products include, for example, 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 Corporation; NUC-9060 and ENGAGE-8100 manufactured by NUC Corporation; NUCG-5130 manufactured by Dow Elastomer Company (all are trade names), etc.

[0073] <(B) Ethylene-vinyl acetate copolymer resin>

[0074] The resin composition of the present invention contains component (A) and (B) ethylene-vinyl acetate copolymer resin as resin components constituting the base resin together. Regarding the resin composition of the present invention, in 100 parts by mass of the total content of component (A) and (B), the content of component (B) is 60 to 95 parts by mass. From the aspect 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.

[0075] In particular, from the aspect of making the insulated wire formed by coating the conductor with this resin composition flexible, in 100 parts by mass of the total content of component (A) and (B), the content of component (B) is preferably 80 to 95 parts by mass, more preferably 90 to 95 parts by mass. In addition, from the aspect of imparting abrasion resistance to the insulated wire formed by coating the conductor with this resin composition, the content of the above-mentioned component (B) is preferably 60 to 80 parts by mass, more preferably 60 to 70 parts by mass.

[0076] It should be noted that the polymerization form of the ethylene-vinyl acetate copolymer used in the present invention can be any one of block, random, and graft.

[0077] In component (B), the content ratio of the vinyl acetate component in component (B) is 40% by mass or less. From the aspect of adjusting the adhesion between the resin-coated material and the conductor to an appropriate level, the content ratio of the vinyl acetate component is preferably 30% by mass or less, more preferably 20% by mass or less. In addition, from the same aspect as above, the content ratio of the vinyl acetate component is preferably 7% by mass or more, more preferably 9% by mass or more. By making the content ratio of the vinyl acetate component within the above range, the resin-coated material made of the resin composition of the present invention can obtain sufficient mechanical properties such as tensile strength and elongation at break, and can further improve the flame retardancy of the insulated wire.

[0078] In addition, from the aspect of imparting a desired adhesion force between the resin-coated material and the conductor, the VA value calculated by the following formula is preferably 7 to 30, more preferably 8 to 28, further preferably 10 to 25, and also preferably 10 to 20.

[0079] VA value = [content of component (B) (parts by mass) in 100 parts by mass of the total content of components (A) and (B)] × [proportion of vinyl acetate component in component (B) (% by mass)] / 100

[0080] The melt flow rate (MFR) of component (B) used in the present invention is preferably 0.1 to 10 g / 10 minutes (load 2.16 kg, temperature 190 °C), more preferably 0.5 to 5 g / 10 minutes.

[0081] By making the melt flow rate of component (B) within the above preferred range, the load on the kneading machine or extruder can be further suppressed during the preparation of the resin composition, during the production of the insulated wire or wire harness, and the dispersibility of each component in the resin composition can be further improved.

[0082] The melt flow rate (MFR) can be determined in the same manner as above.

[0083] The ethylene-vinyl acetate copolymer (B) 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 EVAFLEX V5961, EVAFLEX V5274, and EVAFLEX EV170 (all are trade names) manufactured by Mitsui DuPont Polymer Chemical Co., Ltd.

[0084] Regarding the total content of the above components (A) and (B) in the resin composition of the present invention, from the aspects of improving the adhesion between the resin coating material and the conductor, as well as imparting flexibility and abrasion resistance, it is preferably 7 to 80% by mass, more preferably 10 to 75% by mass, and further preferably 20 to 70% by mass. In addition, the total content of the above components (A) and (B) in the resin composition is also preferably 30 to 80% by mass, also preferably 40 to 75 parts by mass, and also preferably 50 to 75 parts by mass.

[0085] <(C) Thioether compound and (D) Fluororubber>

[0086] The resin composition of the present invention contains at least one of a specific amount of (C) thioether compound and (D) fluororubber. Thereby, when the resin composition is coated around the conductor, the adhesion force between the conductor and the resin coating material can be controlled, and the film-forming property during coating (during wire manufacturing) and the processability of the coated wire can be improved.

[0087] In the resin composition of the present invention, relative to 100 parts by mass of the total content of the above components (A) and (B), the total content of components (C) and (D) is 0.05 to 1 part by mass. From the aspect 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, and it can also be 0.1 to 0.8 part by mass, and it can also be 0.1 to 0.5 part by mass.

[0088] In the present invention, regarding "the total content of components (C) and (D)", when the resin composition contains only any one of components (C) and (D), it refers to the content of the one component contained in the resin composition; when both components (C) and (D) are included, it refers to the total content of components (C) and (D). The resin composition of the present invention preferably contains only any one of components (C) and (D).

[0089] When the resin composition of the present invention contains component (C) and does not contain component (D), relative to 100 parts by mass of the total content of the above components (A) and (B), the content of component (C) is 0.05 to 1 part by mass. In this case, relative to 100 parts by mass of the total content of the above components (A) and (B), the content of component (C) is preferably 0.1 to 1 part by mass.

[0090] In addition, when the resin composition of the present invention contains component (D) and does not contain component (C), relative to 100 parts by mass of the total content of the above components (A) and (B), the content of component (D) is 0.05 to 1 part by mass. In this case, relative to 100 parts by mass of the total content of the above components (A) and (B), the content of component (D) is preferably 0.1 to 1 part by mass.

[0091] ((C) Thioether compound)

[0092] Regarding the component (C) that can be used in the present invention, as long as it is a compound having a thioether bond, it can be used without particular limitation, but preferably its melting point is 60 °C or lower. As such thioether compounds, thioether-based antioxidants (antioxidants having a thioether bond) used as antioxidants for wire coatings can be cited. For example, dilauryl 3,3'-thiodipropionate (melting point: 40 - 42 °C), dimyristyl 3,3'-thiodipropionate (melting point: 48 - 53 °C), distearyl 3,3'-thiodipropionate (melting point: 65 - 67 °C), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate] (melting point: 46 - 52 °C, alias: bis[3-(dodecylthio)propanoic acid] 2,2-bis[[3-(dodecylthio)-1-oxopropyl]oxy]methyl]-1,3-propanediyl), etc. Among these, from the aspect of improving long-term thermal stability and extraction resistance, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate] is preferred.

[0093] The resin composition of the present invention can use commercially available thioether-based antioxidants. As commercially available products, for example, ADKSTAB AO-412S (trade name, manufactured by ADEKA Corporation) can be cited.

[0094] ((D) Fluororubber)

[0095] As the component (D) that can be used in the present invention, rubbers that are homopolymers or copolymers containing fluorine atoms in the main chain or side chain can be cited. Fluororubbers are usually obtained by (co)polymerizing monomers containing fluorine atoms.

[0096] As such a component (D), there is no particular limitation, but copolymers of perfluorohydrocarbons such as tetrafluoroethylene and hexafluoropropylene and partially fluorinated hydrocarbons (e.g., vinylidene fluoride), and copolymers of these perfluorohydrocarbons and / or fluorinated monomers with hydrocarbons such as ethylene and / or propylene can be cited.

[0097] Specifically, tetrafluoroethylene-propylene copolymer rubber (FEPM), tetrafluoroethylene-fluorinated (e.g., hexafluoro) propylene copolymer rubber, tetrafluoroethylene-perfluorovinyl ether copolymer rubber (FFKM), vinylidene fluoride rubber (FKM, e.g., vinylidene fluoride-hexafluoropropylene copolymer rubber), etc. can be cited.

[0098] Copolymer rubbers of the above-mentioned perfluorohydrocarbons and / or fluorinated monomers with chloroprene and / or chlorosulfonated polyethylene can also be cited.

[0099] Among these fluororubbers, tetrafluoroethylene-propylene copolymer rubber and vinylidene fluoride-hexafluoropropylene copolymer rubber are preferred, and tetrafluoroethylene-propylene copolymer rubber is more preferred.

[0100] The resin composition of the present invention can use commercially available fluororubbers. As commercially available products, for example, Viton FreeFlow10 (trade name, manufactured by Chemours Company) can be cited.

[0101] In particular, in 100 parts by mass of the total content of components (A) and (B) in the resin composition, when the content of component (A) is 5 parts by mass or more and 20 parts by mass or less, and the content of component (B) is 80 parts by mass or more and 95 parts by mass or less, from the aspect of suppressing the adhesion force between the resin coating material composed of the resin composition and the conductor, 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, relative to 100 parts by mass of the total content of the above components (A) and (B). In this case, the resin composition preferably contains only any one of components (C) and (D).

[0102] In addition, in 100 parts by mass of the total content of components (A) and (B) in the resin composition, when the content of component (A) exceeds 20 parts by mass and is 40 parts by mass or less, and the content of component (B) is 60 parts by mass or more and less than 80 parts by mass, from the aspect of suppressing the adhesion force between the resin coating material composed of the resin composition and the conductor, and from the aspect of suppressing bleeding or blooming (hereinafter, they are simply collectively referred to as "bleeding"), the content of component (D) is preferably 1 part by mass or less, more preferably 0.8 part by mass or less, also preferably 0.6 part by mass or less, and also preferably 0.5 part by mass or less, relative to 100 parts by mass of the total content of the above components (A) and (B). In this case, it is preferred that the resin composition does not contain component (C) and contains 0.3 part by mass or more of component (D).

[0103] In addition, similarly to the above, in 100 parts by mass of the total content of components (A) and (B) in the resin composition, when the content of component (A) exceeds 20 parts by mass and is 40 parts by mass or less, 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 0.7 part by mass or less, more preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less. In this case, it is preferred that component (D) is not contained and 0.1 part by mass or more of component (C) is contained.

[0104] In addition, when the VA value is 15 or more, from the aspect of suppressing the adhesion between the resin coating material composed of the resin composition and the conductor, 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, relative to 100 parts by mass of the total content of the above components (A) and (B). The VA value in this case is preferably 30 or less, more preferably 28 or less.

[0105] <Other components>

[0106] The resin composition of the present invention may also contain other components such as the following flame retardants, antioxidants, processing aids, crosslinking aids, etc. within the range that does not impair the effects of the present invention in addition to the above components.

[0107] <Flame retardant>

[0108] The present invention may contain a flame retardant within the range that does not impair the effects achieved by the present invention. Examples of such flame retardants include bromine-based flame retardants and antimony-based flame retardants. The present invention preferably contains at least any one of a bromine-based flame retardant and an antimony-based flame retardant, and more preferably contains both a bromine-based flame retardant and an antimony-based flame retardant. In addition, regarding the mixing ratio of the bromine-based flame retardant and the antimony-based flame retardant, in terms of the molar ratio of bromine element to antimony element, it is preferably within the range of an amount of bromine that is 2 to 5 times the molar amount of antimony element contained in the resin composition. That is, relative to the molar content of the antimony-based flame retardant, it is preferably to contain a bromine-based flame retardant with a bromine amount of 2 to 5 times the molar amount.

[0109] When the resin composition of the present invention contains a flame retardant, it is preferably to contain 33 to 45 parts by mass of the flame retardant in total relative to 100 parts by mass of the total content of components (A) and (B).

[0110] (Bromine-based flame retardant)

[0111] The bromine-based 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 bromine-based flame retardants include N,N'-ethylene bisphthalimide bromide or compounds derived therefrom (collectively referred to as "N,N'-ethylene bisphthalimide bromide compounds"), N,N'-bis(bromophenyl)terephthalamide or compounds derived therefrom (collectively referred to as "N,N'-bis(bromophenyl)terephthalamide compounds"), brominated bisphenols or compounds derived therefrom (collectively referred to as "brominated bisphenol compounds"), and organic bromine-containing flame retardants such as 1,2-bis(bromophenyl)alkane. Among them, for example, it is preferred to use N,N'-ethylene bisphthalimide bromide and / or 1,2-bis(bromophenyl)ethane.

[0112] By using N,N'-ethylene bisphthalimide bromide and / or 1,2-bis(bromophenyl)alkane, preferably using 1,2-bis(pentabromophenyl)ethane as a flame retardant, a resin coating material that substantially does not produce overflow can be formed.

[0113] As the bromine-based flame retardant for the resin composition of the present invention, commercially available bromine-based flame retardants can be used. As commercially available products, for example, SAYTEX 8010 (trade name, manufactured by Albemarle Corporation) can be cited.

[0114] When the resin composition of the present invention contains a bromine-based flame retardant, it is preferably contained in an amount of 15 to 35 parts by mass with respect to 100 parts by mass of the total content of components (A) and (B).

[0115] (Antimony-based flame retardant)

[0116] As the antimony-based flame retardant, for example, antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate can be cited. It is considered that antimony reacts with chlorine (halogen), and since the generated gas shields oxygen, the formation of a carbonized layer is promoted, and free radicals are captured (thermal decomposition chain reaction stopping action). Among them, from the aspect of forming a more stable carbonized layer, antimony trioxide is preferably contained in the present invention.

[0117] Commercially available antimony trioxide can be used in the present invention. As commercially available products, for example, PATOX-C (trade name, manufactured by Nippon Seiko Co., Ltd.) can be cited.

[0118] When the resin composition of the present invention contains an antimony-based flame retardant, it is preferably contained in an amount of 5 to 15 parts by mass with respect to 100 parts by mass of the total content of components (A) and (B).

[0119] (Other flame retardants)

[0120] In addition to the above-mentioned bromine-based flame retardant and antimony-based flame retardant, the resin composition of the present invention may also contain a flame retardant that can generally be used for the insulating coating of insulated wires. As such a flame retardant, for example, metal hydroxides such as magnesium hydroxide and aluminum hydroxide (hydroxide-based flame retardants) can be cited. When the resin composition of the present invention contains a hydroxide-based flame retardant, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, with respect to 100 parts by mass of the total content of components (A) and (B).

[0121]

[0122] The resin composition of the present invention may contain an antioxidant. As such an antioxidant, for example, phenolic compounds (phenolic antioxidants) and imidazole compounds (imidazole antioxidants) can be cited.

[0123] When the resin composition of the present invention contains an antioxidant, it is preferably contained in an amount of 2 to 6 parts by mass in total based on 100 parts by mass of the total content of components (A) and (B).

[0124] (Phenolic antioxidant)

[0125] Examples of the phenolic antioxidant that can be used in the resin composition of the present invention include triethylene glycol-bis(3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate), 1,6-hexanediol-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), pentaerythritol-tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, etc. Among these, from the aspect of imparting high heat resistance to automotive wiring harnesses, substances having two or more 3,5-di-tert-butyl-4-hydroxyphenyl or 3,5-di-tert-butyl-4-hydroxybenzyl are preferred, and tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate and pentaerythritol-tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) are particularly preferred.

[0126] Commercially available phenolic antioxidants can be used in the present invention. As commercially available products, for example, Irganox 1010 (trade name, manufactured by BASF) can be cited.

[0127] When the resin composition of the present invention contains a phenolic antioxidant, it is preferably contained in an amount of 0.5 to 2 parts by mass based on 100 parts by mass of the total content of components (A) and (B).

[0128] (Imidazole antioxidant)

[0129] Examples of the imidazole antioxidant that can be used in the resin composition of the present invention include 2-thiobenzimidazole, 2-thiomethylbenzimidazole, 4-thiomethylbenzimidazole, 5-thiomethylbenzimidazole, and zinc salts thereof, etc. 2-thiobenzimidazole and its zinc salt are preferred.

[0130] Commercially available imidazole antioxidants can be used in the present invention. As commercially available products, for example, NOCRAC MBZ (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.) can be cited.

[0131] When the resin composition of the present invention contains an imidazole antioxidant, it is preferably contained in an amount of 1 to 4 parts by mass based on 100 parts by mass of the total content of components (A) and (B).

[0132] <Processing aid

[0133] The resin composition of the present invention preferably contains a processing aid. Preferred examples of the processing aid include metal soaps (lubricants).

[0134] Examples of the metal soap (lubricant) that can be used in the resin composition of the present invention include calcium stearate, zinc stearate, magnesium stearate, etc.

[0135] The present invention can use commercially available metal soaps. Examples of commercially available products include SHINACALEAD ZS-101 (trade name, manufactured by Shinagawa Chemical Co., Ltd.).

[0136] When the resin composition of the present invention contains a metal soap, it is preferably contained in an amount of 0.5 to 2 parts by mass relative to 100 parts by mass of the total content of components (A) and (B).

[0137] <Crosslinking aid

[0138] The resin composition of the present invention preferably contains a crosslinking aid. Examples of the crosslinking aid include polyfunctional compounds, and compounds having two or more (preferably three or more, more preferably 3 to 6) ethylenically unsaturated bonds (carbon-carbon double bonds) in the molecule are preferred.

[0139] 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, divinyl compounds, etc.

[0140] The present invention can use commercially available crosslinking aids. Examples of commercially available products include Ogmont T200 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0141] In the resin composition of the present invention, it is preferably contained in an amount of 1 to 4 parts by mass of the crosslinking aid relative to 100 parts by mass of the total content of components (A) and (B).

[0142] <Additive

[0143] In the resin composition of the present invention, various additives can be appropriately blended as necessary within the range not impairing the effects of the present invention, for example, copper inhibitors, ultraviolet absorbers, dispersants, plasticizers, fillers, pigments, etc. Examples of such additives include zinc compounds. Specific examples of the zinc compound include zinc sulfide and zinc oxide.

[0144] [Method for producing resin composition]

[0145] The resin composition of the present invention can be obtained by blending the above components (A) to (D) and, if necessary, any of the above components, and subjecting them to melt-kneading using a batch kneader such as a roll, kneader, Banbury mixer, or a commonly used kneading device such as a twin-screw extruder.

[0146] [Insulated wire]

[0147] The insulated wire of the present invention has a layer formed 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 wire). It should be noted that the insulated wire of the present invention may have an intermediate layer or a shielding layer between the layer formed of the conductor and the resin coating material.

[0148] When the cross-sectional area of the insulated wire of the present invention is 2 sq (square millimeters, JIS standard) or less, from the aspect of imparting abrasion resistance to the insulated wire, it is preferable to mix a large amount of the polyethylene resin of component (A) in the resin composition of the present invention as the film-forming material. Specifically, in 100 parts by mass of the total content of components (A) and (B) in the resin composition of the present invention, the content of component (A) is preferably 20 to 40 parts by mass, more preferably 30 to 40 parts by mass. In addition, when the content of component (A) in the base resin is within the above range, from the aspect of suppressing bleeding, it is preferable to suppress the mixing amount of the thioether compound of component (C) and use the fluororubber of component (D) as the main body, thereby controlling the adhesion between the wire coating material and the conductor.

[0149] In addition, when the cross-sectional area of the insulated wire of the present invention is 3 sq or more, from the aspect of imparting flexibility to the insulated wire, it is preferable to mix a large amount of the ethylene-vinyl acetate copolymer of component (B) in the resin composition of the present invention as the film-forming material. Specifically, in 100 parts by mass of the total content of components (A) and (B) in the resin composition of the present invention, the content of component (B) is preferably 80 to 95 parts by mass, more preferably 90 to 95 parts by mass.

[0150] [Automobile wiring harness]

[0151] The automobile wiring harness of the present invention has the insulated wire of the present invention. The resin composition of the present invention has excellent appearance and also has excellent flame retardancy and mechanical properties. Therefore, a wiring harness assembled with an insulated wire (the insulated wire having a layer formed of a resin coating material obtained by crosslinking the resin composition of the present invention) can be suitably used for automobile applications.

[0152] Hereinafter, the automobile wiring harness may sometimes be simply referred to as a "wiring harness".

[0153] [Method for manufacturing an insulated wire for an automobile wiring harness]

[0154] The insulated wire for automotive wiring harness of the present invention can be obtained through the following process: Extrude and coat the resin composition of the present invention on a conductor to form a layer of the resin composition, and irradiate the layer of the resin composition with electron beams of 80 to 250 kGy. Through this electron beam irradiation, a cross-linking reaction occurs in the layer of the resin composition to form a resin coating layer.

[0155] As the conductor, it can be a single wire or a stranded wire, and it can be a bare wire, or a wire coated with tin or enamel. As the metal material for forming the conductor, examples include soft copper, copper alloy, aluminum, etc. There is no particular limitation on the thickness of the layer formed by the resin coating material around the conductor, but it is usually about 0.15 to 5 mm.

[0156] There is no particular limitation on the conductor diameter, the material of the conductor, the thickness of the coating layer, etc., and they can be appropriately determined according to the purpose or use. The cross-linking reaction by electron beam irradiation can be carried out under normal methods and conditions without limitation. Regarding the irradiation conditions of the electron beam, the irradiation dose is preferably 50 to 450 kGy, more preferably 80 to 250 kGy, further preferably 80 to 200 kGy, and particularly preferably 80 to 160 kGy. In addition, the acceleration voltage is preferably 300 to 3000 keV, more preferably 500 to 2500 keV.

[0157] In addition, a multi-layer structure such as an intermediate layer or a shielding layer can also be provided between the conductor and the coating layer, or between the coating layers.

[0158] Regarding the conditions for extruding and molding the resin composition of the present invention, as long as the resin composition of the present invention can be extruded, there is no particular limitation. However, from the aspect of being able to reduce the load on the extruder (extrusion molding machine) and also ensure the shape maintainability, the extrusion temperature (head) is preferably 100 to 230 °C, more preferably 120 to 200 °C.

[0159] In addition, other conditions for extrusion molding can be appropriately set according to the purpose.

[0160] There is no particular limitation on the screw configuration of the extruder, and conventional full-thread screws, double-thread screws, front-end double-thread screws, Maddock screws, etc. can be used.

[0161] Regarding the shape and material of the conductor, any conductor can be used as long as it is the shape and material (such as copper, aluminum, etc.) commonly used for insulated wires in automotive wiring harnesses.

[0162] In addition, there is no particular limitation on the thickness of the resin coating layer. When using the resin composition of the present invention, it has the following advantages: Even if the thickness of the resin coating layer is thinned, an insulated wire with excellent flexibility, hardness, cross-linking degree, flame retardancy, cold resistance, and heat resistance can be obtained.

[0163] Example

[0164] The present invention will be further described in detail based on the following examples and comparative examples, but the present invention is not limited to these.

[0165] [Examples 1 to 8 and Comparative Examples 1 to 9]

[0166] The materials for preparing the resin compositions of Examples 1 to 8 and Comparative Examples 1 to 9 are shown in Tables 1 and 2 below. The details of the materials used are as described below. It should be noted that the following (1) to (18) correspond to (1) to (18) in Tables 1 and 2 below.

[0167] [Materials Used]

[0168] (Component (A): Polyethylene (PE) resin)

[0169] (1): NUC-9060 (trade name), manufactured by NUC Corporation, density 0.923 g / cm 3

[0170] (2): NUCG-5130 (trade name), manufactured by Dow Elastomer Company, density 0.923 g / cm 3

[0171] (3): ENGAGE-8100 (trade name), manufactured by NUC Corporation, density 0.870 g / cm 3

[0172] (4): HI-ZEX-5305E (trade name), manufactured by PRIME POLYMER Company, density 0.950 g / cm 3

[0173] (5): ADTEX L6100M (trade name), manufactured by Japan Polyolefins Co., Ltd., density 0.920 g / cm 3 , maleic acid modified

[0174] (Component (B): Vinyl acetate copolymer resin)

[0175] (6): EVAFLEX V5961 (trade name), manufactured by Mitsui DuPont Polychemicals Co., Ltd., content of vinyl acetate component: 9% by mass

[0176] (7): EVAFLEX V5274 (trade name), manufactured by Mitsui DuPont Polychemicals Co., Ltd.

[0177] Content of vinyl acetate component: 17% by mass

[0178] (8): EVAFLEX EV170 (trade name), manufactured by Mitsui DuPont Polychemical Co., Ltd., content of vinyl acetate component: 33% by mass

[0179] (9): EVAFLEX EV40LX (trade name), manufactured by Mitsui DuPont Polychemical Co., Ltd., content of vinyl acetate component: 41% by mass

[0180] (10): EVAFLEX EV45LX (trade name), manufactured by Mitsui DuPont Polychemical Co., Ltd., content of vinyl acetate component: 46% by mass

[0181] (Component (C): thioether compound)

[0182] (11): 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-dodecylthiopropionate], ADKSTAB AO-412S (trade name), manufactured by ADEKA Corporation

[0183] (Component (D): fluororubber)

[0184] (12): Viton FreeFlow10 (trade name), manufactured by Chemours Company

[0185] (Flame retardant)

[0186] (13): 1,2-bis(pentabromophenyl)ethane, SAYTEX 8010 (trade name), manufactured by Albemarle Corporation

[0187] (14): Antimony trioxide, PATOX-C (trade name), manufactured by Nippon Concentrates Co., Ltd.

[0188] (Antioxidant)

[0189] (15): Pentaerythritol-tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), phenolic antioxidant, Irganox1010 (trade name), manufactured by BASF Corporation

[0190] (16): Imidazole-based antioxidant, zinc salt of 2-sulfanylbenzimidazole, NOCRAC MBZ (trade name), manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0191] (Processing aid)

[0192] (17): Zinc stearate, SHINACALEAD ZS-101 (trade name), manufactured by Shinagawa Chemical Co., Ltd.

[0193] (Crosslinking aid)

[0194] (18): Trimethylolpropane trimethacrylate, Ogmont T200 (trade name), manufactured by Shin-Nakamura Chemical Co., Ltd.

[0195] <Manufacture of Resin Composition Pellets>

[0196] According to the compositions shown in Tables 1 and 2 below, melt-knead using a 1.7-liter Banbury mixer at 180 °C, discharge the mixture, and pelletize through an extruder to obtain the resin composition pellets of Examples 1 to 8 and Comparative Examples 1 to 9.

[0197] <Manufacture of Insulated Electric Wire>

[0198] Use an extruder with a temperature set at 130 - 190 °C to extrude and coat each of the above-obtained resin composition pellets onto a conductor. Crosslinking reaction occurs by irradiating the layer of the formed resin composition with electron beams. Thus, an insulated electric wire with an insulating film having a thickness of 0.7 mm is obtained around a conductor made of copper with a cross-sectional area of 3 mm 2 (≒3 sq) and a circular cross-section.

[0199] It should be noted that the crosslinking using electron beams is carried out under the conditions of an acceleration voltage of 800 keV and 160 kGy.

[0200] [Performance Evaluation]

[0201] Use each of the insulated electric wires manufactured as above for the following performance evaluation.

[0202] <Surface Smoothness>

[0203] The surface smoothness (extrusion appearance) of each insulated electric wire was measured as follows.

[0204] Use a laser microscope (LASER MICROSCOPE VK-X250, manufactured by KEYENCE Corporation) to measure the surface of each insulated electric wire along the length direction under the conditions of a stylus tip radius of curvature of 2 μm and a static measuring force at the average position of the stylus of 0.75 mN. The measurement is carried out 3 times (N = 3), and the average value is taken as the arithmetic mean roughness Ra (μm). Evaluate the calculated arithmetic mean roughness Ra according to the following criteria. It should be noted that evaluations A and B are considered qualified.

[0205] -Evaluation Criteria-

[0206] A: Ra is less than 2 μm

[0207] B: Ra is 2 μm or more and less than 3 μm

[0208] C: Ra is 3 μm or more

[0209] <Extrusion Processability>

[0210] When the conductor is extruded to a length of about 5000 m under the above conditions, the resin residue (mold residue, eye mucus-like accumulation) accumulated at the extrusion port and the resin residue attached to the insulated wire are evaluated using the following criteria. Evaluations A and B are considered qualified. It should be noted that the resin residue attached to the insulated wire obtained by extrusion molding is removed in sequence using an air gun. The air gun used (trade name: AG45, manufactured by Kurita Manufacturing Co., Ltd.) has a tip diameter of: Air pressure: 0.5MPa.

[0211] -Evaluation Criteria-

[0212] A: When 5000 m was manufactured, there was no accumulation or adhesion of resin residue at the extrusion outlet and the insulated wire.

[0213] B: When 5000 m was produced, resin slag was deposited at the extrusion outlet, but after spraying with an air gun, no adhesion of resin slag was observed on the insulated wire.

[0214] C: When 5000 m was produced, resin slag was accumulated at the extrusion outlet, and after spraying with an air gun, adhesion of resin slag was observed on the insulated wire.

[0215] <Overflow>

[0216] The insulated wire precursor (before electron beam irradiation) extruded and coated with the resin composition (length: 200 mm) was kept at 40°C for 1 hour. A SUS304 round rod ( Hereinafter, it is also referred to as "SUS rod". ) The amount of attachment from each insulated wire attached to the SUS304 round rod (attachment of the surface exudate component of the insulated wire) was evaluated by moving back and forth 10 times (1 round trip: 200 mm × 2 times) in the longitudinal direction of the insulated wire precursor in a positional relationship perpendicular to the longitudinal direction of the insulated wire precursor. It should be noted that evaluations A and B were set as qualified based on visual observation of the adhesion of the exudate component.

[0217] -Evaluation Criteria-

[0218] A: There is absolutely no adhesion of exudate.

[0219] B: The adhesion area of the oozing component is less than half of the contact area between the insulated wire precursor and the SUS rod.

[0220] C: The adhesion area of the oozing component is half or more of the contact area between the insulated wire precursor and the SUS rod.

[0221] <Close fit>

[0222] The adhesion force between the insulating coating and the conductor is measured by the method according to the Japan Automobile Manufacturers Association Standard JASO D618.

[0223] Among 75 mm of the insulated wire, the insulating coating is removed from the front end to 25 mm to expose the conductor. The pulling speed is set at 250 mm / min at room temperature (23°C), and the maximum pulling force until the resin coating peels off from the conductor is measured when the conductor is pulled. The measurement results are evaluated according to the following criteria. Note that evaluations A and B are considered qualified.

[0224] - Evaluation Criteria -

[0225] A: The maximum pulling force is 10 N or more and less than 40 N

[0226] B: The maximum pulling force is 40 N or more and less than 80 N

[0227] C1: The maximum pulling force is less than 10 N

[0228] C2: The maximum pulling force is 80 N or more

[0229] <Flame Retardancy>

[0230] According to the International Organization for Standardization (ISO) 19642, an inclined burning test is carried out. A wire specimen with a length of 600 mm cut from each insulated wire is prepared and supported with the specimen inclined at about 45 degrees with respect to the horizontal. Using a Bunsen burner with a diameter of 10 mm, the front end of the reducing flame of 50 mm is directed at a position 500 ± 5 mm from the upper end of the specimen for 30 seconds or until the conductor is exposed, and the afterglow time after the flame quietly extinguishes is measured and evaluated according to the following criteria. Note that evaluations A and B are considered qualified.

[0231] - Evaluation Criteria -

[0232] A: The afterglow time is less than 5 seconds

[0233] B: The afterglow time is 5 seconds or more and less than 30 seconds

[0234] C: The afterglow time is 30 seconds or more

[0235] <Tensile Properties>

[0236] The coating material of the insulated wire is taken and evaluated according to the following criteria based on the Japanese Industrial Standard (JIS) K7161.

[0237] Tubular samples with the conductors removed from each insulated wire were prepared, and the tensile strength (breaking strength, MPa) and elongation at break (%) were measured at a gripping distance of 60 mm, a distance between gauge marks of 20 mm, and a tensile speed of 200 mm / min (room temperature, 23 °C). It should be noted that the "elongation at break (%)" refers to the value expressed as a percentage of the increase in the distance between the gauge marks at the time of sample breakage relative to the initial distance between the gauge marks. Therefore, an elongation at break of 100% means that the distance between the gauge marks becomes twice as long. The measured tensile strength and elongation at break were evaluated according to the following evaluation criteria. It should be noted that evaluations A and B are considered qualified.

[0238] - Evaluation Criteria -

[0239] A: Tensile strength of 20 MPa or more and elongation at break of 400% or more

[0240] B: Tensile strength of 15 MPa or more and less than 20 MPa, and / or elongation at break of 300% or more and less than 400%

[0241] C: Tensile strength less than 15 MPa, and / or elongation at break less than 300%

[0242] The obtained results are shown together in Tables 1 and 2 below. The recorded blending amounts in the following tables are parts by mass (mass ratio).

[0243] Table 1

[0244]

[0245] Table 2

[0246]

[0247] <Notes to the Table>

[0248] The content of each component in the table is in parts by mass. Blank columns and "-" mean that the corresponding component is not included.

[0249] Table 2 shows that the insulated wires using resin compositions that do not meet the requirements of the present invention are unqualified in at least 3 evaluation items.

[0250] In contrast, as can be seen from Table 1, the insulated wires made using the resin composition of the present invention are qualified in all evaluation items. From this, it can be seen that the resin composition of the present invention can be suitably used as the resin coating layer of insulated wires.

[0251] Although the present invention and its embodiments have been described together, the applicant believes that, unless otherwise specified, the present invention is not intended to be limited to any details of the description and should be broadly interpreted without departing from the spirit and scope of the invention disclosed in the appended claims.

Claims

1. A resin composition comprising the following components (A) and (B), and containing the following component (C) or (D), (A) Low-density polyethylene resin, (B) Ethylene-vinyl acetate copolymer resin, (C) Sulfide compound, (D) Fluoroelastomer, In 100 parts by mass of the total content of components (A) and (B), the content of component (A) is 5 parts by mass to 40 parts by mass, and the content of component (B) is 60 parts by mass to 95 parts by mass; relative to 100 parts by mass of the total content of components (A) and (B), the content of component (C) or (D) is 0.05 parts by mass to 1 part by mass, The proportion of the vinyl acetate component in component (B) is 40% by mass or less.

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

3. The resin composition according to claim 1 or 2, wherein The VA value calculated by the following formula is 15 or more, and relative to 100 parts by mass of the total content of components (A) and (B), the content of component (C) or (D) is 0.5 parts by mass to 1 part by mass, VA value = [content of component (B) in 100 parts by mass of the total content of components (A) and (B) (parts by mass)] × [proportion of the vinyl acetate component in component (B) (% by mass)] / 100.

4. The resin composition according to claim 1 or 2, wherein, The said resin composition further contains at least one of a flame retardant, an antioxidant, a processing aid, and a crosslinking aid in addition to the said components (A) to (D).

5. The resin composition according to claim 1 or 2, which is used for automotive wiring harnesses.

6. A resin coating material obtained by crosslinking the resin composition according to any one of claims 1 to 5.

7. An insulated electric wire, wherein, The insulating film has the resin coating material according to claim 6.

8. An automotive wiring harness having the insulated wire according to claim 7.

9. A method for manufacturing an insulated wire for an automotive wiring harness, comprising the following steps: extruding and coating the resin composition according to any one of claims 1 to 5 on a conductor to form a layer of the resin composition, and irradiating the layer of the resin composition with electron beams of 80 kGy to 250 kGy.

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