JP2023090406A - Resin composition, coated wire and wire harness - Google Patents

Abstract

To provide a resin composition that suppresses discoloration due to irradiation with electron beams and the like during crosslinking treatment, and has sufficient heat-resistant durability, flame retardancy and bleeding resistance as a coating layer for a wire, and a coated wire and a wire harness each including the same.SOLUTION: A resin composition comprises an ethylene copolymer resin, a flame retardant, and an achromatic pigment with a refractive index of 2.0 or more. The ethylene copolymer resin has been crosslinked. Relative to 100 pts.mass of the ethylene copolymer resin, 30-80 pts.mass of a flame retardant and 1-15 pts.mass of the achromatic pigment are contained.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a resin composition, a coated electric wire and a wire harness.

Insulating materials for insulated wires used in wire harnesses in the engine compartment of automobiles are required to have a high degree of heat resistance and longevity, as well as excellent flexibility, abrasion resistance, flame retardancy, electrical insulation, and the like. Therefore, conventionally, insulated wires using polyvinyl chloride (PVC) or flame-retardant polyethylene crosslinked by irradiation with ionizing radiation such as accelerated electron beams have been widely used. It has been used appropriately.

In recent years, from the viewpoint of reducing the load on the global environment, it is desired to reduce the use of materials containing halogen elements. For this reason, Patent Document 1 discloses a non-halogen insulated wire using, as a coating layer, a crosslinked flame-retardant polyolefin resin mixed with magnesium hydroxide as a flame retardant.

JP 2008-117691 A

However, as in Patent Document 1, a relatively large amount of magnesium hydroxide is added in order to impart sufficient flame retardancy to the polyolefin resin, and as a result, deterioration of the polyolefin resin is accelerated. become. Also, in order to achieve both flame retardancy and heat resistance life, it is necessary to add a large amount of antioxidant. In this case, there is a problem that the antioxidant added in a large amount bleeds to the surface of the insulating layer of the electric wire, which lowers the workability in manufacturing the electric wire. On the other hand, there is also a problem that the resin composition is discolored after being irradiated with an accelerated electron beam or the like in order to crosslink the resin. Therefore, when a non-halogen flame-retardant resin composition is used as a material for a coating layer of an electric wire in which a cable is identified by the color of the insulating layer, the desired hue may not be obtained, making it difficult to identify the cable.

The present invention has been made in view of the problems of the prior art. An object of the present invention is to suppress discoloration due to irradiation with electron beams or the like during crosslinking treatment, and to provide a resin composition having sufficient heat resistance life, flame retardancy and bleeding resistance as a coating layer for electric wires, and a resin composition using the same. It is to provide a covered electric wire and a wire harness.

A resin composition according to an aspect of the present invention contains an ethylene copolymer resin, a flame retardant, and an achromatic pigment having a refractive index of 2.0 or more, and the ethylene copolymer resin is crosslinked. , containing 30 to 80 parts by weight of a flame retardant and 1 to 15 parts by weight of an achromatic pigment with respect to 100 parts by weight of an ethylene copolymer resin.

A coated wire according to another aspect of the present invention includes a conductor and a coating layer that coats the conductor and contains a resin composition.

A wire harness according to another aspect of the present invention includes a covered electric wire.

INDUSTRIAL APPLICABILITY According to the present invention, a resin composition that suppresses discoloration due to irradiation with an electron beam or the like during cross-linking treatment and has sufficient heat resistance life, flame retardancy and bleeding resistance as a coating layer for electric wires, and a coating using the same Electrical wires and wire harnesses can be provided.

It is a typical sectional view showing an example of a covering electric wire concerning this embodiment.

Hereinafter, the resin composition, coated electric wire, and wire harness according to the present embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

[Resin composition]
The resin composition according to this embodiment contains an ethylene copolymer resin, a flame retardant, and an achromatic pigment having a refractive index of 2.0 or more.

(ethylene copolymer resin)
The ethylene copolymer resin can be obtained by polymerizing an ethylene monomer and a comonomer other than the ethylene monomer. Ethylene copolymer resins are copolymers of ethylene monomers and greater than 5 mol % of olefinic monomers other than ethylene monomers, and copolymers of ethylene monomers and greater than 1 mol % of non-olefinic monomers. Examples of ethylene copolymer resins include ethylene-vinyl ester copolymers, ethylene-α,β-unsaturated carboxylic acid and/or alkyl ester copolymers thereof, ethylene-vinyl acetate copolymers (EVA), ethylene - methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-butyl acrylate copolymer (EBA), ethylene-vinyl acetate-ethyl acrylate A copolymer etc. can be mentioned. These ethylene copolymer resins may be used singly or in combination. Also, the ethylene copolymer resin may or may not be modified with maleic acid, maleic anhydride, or the like.

The comonomer content in the ethylene copolymer resin is not particularly limited, but is preferably 10% by mass or more, more preferably 15% by mass or more. By setting the comonomer content in the ethylene copolymer resin to 15% by mass or more, it is possible to exhibit sufficient flexibility and suppress the addition of additives for satisfying the intended heat resistance.

Although the content of ethylene contained in the ethylene copolymer resin is not particularly limited, it is preferably 85% by mass or less. By setting the content of ethylene contained in the ethylene copolymer resin to 85% by mass or less, the mechanical properties of the coated wire can be improved.

From the viewpoint of heat resistance, the ethylene copolymer resin is at least one of ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA) and ethylene-butyl acrylate copolymer (EBA). preferably contains one. From the viewpoint of heat resistance, the ethylene copolymer resin is more preferably ethylene-ethyl acrylate copolymer (EEA).

(Flame retardants)
The resin composition contains a flame retardant to improve flame retardancy. Flame retardants are desired to reduce the use of materials containing halogen elements from the viewpoint of suppressing the load on the global environment. Therefore, the organic flame retardant may contain, for example, at least one flame retardant selected from the group consisting of phosphorus flame retardants and nitrogen flame retardants. Moreover, the inorganic flame retardant may contain, for example, at least one of a metal hydrate flame retardant and an antimony flame retardant. From the viewpoint of achieving both flame retardancy and heat resistance life, metal hydrate flame retardants are preferred.

Metal hydrate flame retardants include compounds having hydroxyl groups or water of crystallization such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide, basic magnesium carbonate, hydrated aluminum silicate, and hydrated magnesium silicate, and combinations thereof. be able to. Among these, magnesium hydroxide or aluminum hydroxide is preferable, and magnesium hydroxide, particularly magnesium hydroxide surface-treated with a surface-treating agent described later, is more preferable.

The surface of the metal hydrate flame retardant may be coated with a surface treatment agent in order to facilitate good adhesion to the ethylene copolymer resin. Examples of surface treatment agents include higher aliphatic carboxylic acids having about 6 to 25 carbon atoms (lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, linoleic acid, etc.), and higher aliphatic carboxylic acids. Alkali metal salt or alkaline earth metal salt (lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, magnesium salt, sodium salt, potassium salt, calcium salt of linoleic acid, etc.), carbon number 6- Higher chain alcohols of about 30, higher fatty acid esters, and the like. These may be used in combination of multiple types.

When magnesium hydroxide is used as the flame retardant, the particle size of magnesium hydroxide is preferably 0.5 μm or more and 20 μm or less. The particle size of magnesium hydroxide is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less, from the viewpoint of excellent appearance when used as a coating layer for electric wires. Moreover, the particle size of magnesium hydroxide is preferably 0.5 μm or more from the viewpoint that secondary agglomeration is less likely to occur and mechanical properties are less likely to be deteriorated.

The content of the flame retardant in the resin composition is 30 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the ethylene copolymer resin. When the content of the flame retardant is 30 parts by mass or more, the flame retardancy of the resin composition can be improved. And it is preferable that the content of the flame retardant is 50 parts by mass or more. Moreover, when the content of the flame retardant is 80 parts by mass or less, sufficient heat resistance can be imparted to the resin composition. And it is preferable that the content of the flame retardant is 60 parts by mass or less.

(achromatic pigment)
The resin composition contains an achromatic pigment having a refractive index of 2.0 or more in order to suppress discoloration due to irradiation with electron beams or the like during cross-linking treatment. When the refractive index of the achromatic pigment is 2.0 or more, the resin composition is given sufficient hiding power, the amount of light reflected on the surface of the pigment in the resin composition is increased, and the cross-linking treatment is performed. Discoloration of the resin composition due to irradiation with electron beams or the like can be suppressed. In addition, since the refractive index of the achromatic pigment is 2.0 or more, the content of the achromatic pigment for the above purpose can be minimized. The refractive index of the achromatic pigment can be measured using an Abbe refractometer based on Japanese Industrial Standard JIS K0062:1992 (method for measuring refractive index of chemical products).

Examples of achromatic pigments having a refractive index of 2.0 or more include white pigments. Examples of the achromatic pigment having a refractive index of 2.0 or more include at least one selected from the group consisting of zinc oxide, titanium dioxide (anatase type, rutile type), barium sulfate, magnesium carbonate, calcium carbonate, silica and alumina. preferably contains one. Zinc oxide or titanium dioxide is more preferable as the achromatic pigment from the viewpoint of imparting sufficient hiding power to the resin composition.

Although the particle size of the achromatic pigment is not particularly limited, it is preferably 0.01 μm to 1 μm, for example, in consideration of dispersibility in the resin composition.

The content of the achromatic pigment in the resin composition is 1 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the ethylene copolymer resin. When the content of the achromatic pigment is 1 part by mass or more, it is possible to impart sufficient hiding power to the resin composition. In addition, since the content of the achromatic pigment is 15 parts by mass or less, aggregation of the achromatic pigment particles is prevented, the appearance of the electric wire is improved, and mechanical properties such as wear resistance are less likely to be adversely affected. . The content of the achromatic pigment is preferably 10 parts by mass or less.

When zinc oxide is used as the achromatic pigment, the content of zinc oxide is preferably 3 to 15 parts by mass, more preferably 3 to 10 parts by mass, with respect to 100 parts by mass of the ethylene copolymer resin. is more preferable.

When titanium dioxide is used as the achromatic pigment, the content of titanium dioxide is preferably 1 to 3 parts by mass with respect to 100 parts by mass of the ethylene copolymer resin.

(Other additives)
As additives, in addition to the above flame retardants and achromatic pigments, antioxidants, cross-linking agents, cross-linking aids, processing aids, plasticizers, metal deactivators, fillers, reinforcing agents, ultraviolet absorbers, stabilizers, agents, pigments, lubricants, dyes, coloring agents, antistatic agents and foaming agents.

In the resin composition of the present embodiment, the content of the flame retardant, the achromatic pigment and the other additives is 75 parts by mass or less when the content of the ethylene copolymer resin is 100 parts by mass. is preferred. By setting the content of the flame retardant, the achromatic pigment, and other additives to 75 parts by mass or less, the flexibility of the resin composition can be improved.

Examples of antioxidants include phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. In order to impart sufficient heat resistance to the resin composition as an antioxidant, an antioxidant such as hindered phenol that scavenges radicals and an antioxidant such as thioether that decomposes peroxides may be combined. Also, the content of the antioxidant is preferably 2 parts by mass or more and 5 parts by mass or less when the content of the ethylene copolymer resin is 100 parts by mass. When the content of the antioxidant is 2 parts by mass or more, sufficient heat resistance life can be provided. In addition, since the content of the antioxidant is 5 parts by mass or less, the antioxidant is suppressed from bleeding onto the surface of the insulating layer of the electric wire, and the workability at the time of manufacturing the electric wire is not adversely affected. can be done.

In this embodiment, the ethylene copolymer resin in the resin composition is crosslinked. By cross-linking the ethylene copolymer resin, the heat resistance of the resin composition can be improved. The method for cross-linking the ethylene copolymer resin is not particularly limited. For example, the ethylene copolymer resin may be cross-linked by irradiation with radiation, or the ethylene copolymer resin may be cross-linked by a cross-linking agent contained in the resin composition. may The ethylene copolymer resin is preferably radiation-crosslinked.

Radiation used for cross-linking may be, for example, gamma rays or electron beams. By irradiating the coating layer with radiation, radicals are generated in the molecules to form intermolecular crosslinks. Radiation irradiation conditions are not particularly limited, but for example, the acceleration voltage is 500 kV to 1000 kV and the irradiation dose is 100 kGy to 250 kGy.

For example, an organic peroxide or the like can be used as the cross-linking agent. Cross-linking agents include, for example, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5- di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, At least one selected from the group consisting of lauroyl peroxide, tert-butyl cumyl peroxide and the like may be used. A single cross-linking agent may be used alone, or a plurality of cross-linking agents may be used in combination. In addition, in the resin composition, the content of the cross-linking agent is preferably 0.05 to 0.10 parts by mass with respect to 100 parts by mass of the ethylene copolymer resin.

The resin composition may contain a cross-linking aid in addition to the cross-linking agent in order to improve the cross-linking efficiency. A polyfunctional compound can be used as a cross-linking aid. The cross-linking aid may be, for example, at least one compound selected from the group consisting of acrylate-based compounds, methacrylate-based compounds, allyl compounds, vinyl compounds, and the like. These polyfunctional compounds may be used alone or in combination. Among these compounds, it is preferable to use trimethylolpropane trimethacrylate because of its high affinity with the ethylene copolymer resin.

In addition, the content of the cross-linking aid in the resin composition is preferably 0.1 to 5 parts by mass, and 0.8 to 2 parts by mass with respect to 100 parts by mass of the ethylene copolymer resin. is more preferable. By setting it as such a range, the heat resistance of a resin composition, workability, and bleeding resistance can be improved more.

Examples of processing aids include petroleum oils such as paraffinic oils and naphthenic oils that are added to rubber materials and the like.

The resin composition is produced by melt-kneading the ethylene copolymer resin, the flame retardant, and the like, and the method can employ known means. For example, after pre-blending using a high-speed mixing device such as a Henschel mixer, the mixture is kneaded using a known kneader such as a Banbury mixer, a kneader, or a roll mill to crosslink the ethylene copolymer resin as described above. A resin composition can be obtained.

Regarding the appearance of the resin composition after cross-linking treatment, it is preferable that the color difference ΔE (difference between L*, a*, b*), which is a value obtained by colorimetric comparison with a reference sample before cross-linking treatment, is 10 or less. , 6 or less. The color difference ΔE in the resin composition after cross-linking treatment is 6 or less, so that the desired hue can be obtained in the resin composition, and the material of the coating film of the electric wire can identify the cable by the color of the insulating layer. can be used as

As described above, the resin composition contains an ethylene copolymer resin, a flame retardant, and an achromatic pigment having a refractive index of 2.0 or more. The ethylene copolymer resin is crosslinked and contains 30 to 80 parts by mass of a flame retardant and 1 to 15 parts by mass of an achromatic pigment with respect to 100 parts by mass of the ethylene copolymer resin. Therefore, the resin composition suppresses discoloration due to irradiation with electron beams or the like during cross-linking treatment, and has sufficient heat resistance life, flame retardancy, and bleeding resistance as a coating layer for electric wires.

[Coated wire]
FIG. 1 is a cross-sectional view showing an example of a coated wire 10 according to this embodiment. As shown in FIG. 1, a covered wire 10 of the present embodiment includes a conductor 11 and a covering layer 12 that covers the conductor 11 and contains the resin composition according to the above embodiment. The resin composition according to the above embodiment has sufficient heat resistance life, flame retardancy and bleeding resistance. Therefore, the covered wire 10 having such a covering layer 12 can be preferably used as the covered wire 10 for automobiles, for example.

The conductor 11 may be composed of only one strand, or may be a bundled strand composed of a plurality of strands bundled together. Moreover, the conductor 11 may be composed of only one twisted wire, or may be a composite twisted wire composed of a bundle of a plurality of bundled twisted wires. The configuration and size of the conductor 11 are preferably those specified in at least one of JASO D624 and ISO 6722-1.

Although the diameter of the conductor 11 is not particularly limited, it is preferably 4.0 mm or more, more preferably 5.0 mm or more. By setting the diameter of the conductor 11 as described above, the resistance of the conductor can be reduced and, for example, even a large-capacity battery can be charged in a short time. Although the diameter of the conductor 11 is not particularly limited, it is preferably 25 mm or less, more preferably 20 mm or less. By setting the diameter of the conductor 11 as described above, it is possible to easily route the covered electric wire 10 even in a narrow and short route.

Although the diameter of the wire is not particularly limited, it is preferably 0.1 mm or more, and more preferably 0.2 mm or more. By setting the diameter of the wire as described above, cutting of the wire can be suppressed. Although the diameter of the wire is not particularly limited, it is preferably 0.5 mm or less, more preferably 0.4 mm or less. By setting the wire diameter as described above, it is possible to facilitate wiring of the covered electric wire 10 even in a narrow and short path.

Although the material constituting the conductor 11 is not particularly limited, it is preferably at least one conductive metal material selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, and the like.

Although the thickness of the coating layer 12 is not particularly limited, it is preferably 0.5 mm or more, more preferably 0.65 mm or more. By setting the thickness of the coating layer 12 as described above, the conductor 11 can be effectively protected. The thickness of the coating layer 12 is not particularly limited, but is preferably 2.0 mm or less, more preferably 1.85 mm or less. By setting the thickness of the coating layer 12 as described above, the wiring of the coated wire 10 can be facilitated even in a narrow and short path.

The covered electric wire 10 may further include a shield layer covering the covering layer 12 and a sheath layer further covering the shield layer. The shield layer can prevent unnecessary emission of electromagnetic waves from the conductor 11 . The shield layer can be formed by weaving a conductive metal foil, a foil containing a metal, or a metal wire (metal conductor) in a mesh shape. The sheath layer can effectively protect and bind the shield layer. Although the sheath layer is not particularly limited, an olefin resin such as polyethylene may be used, or the resin composition according to the above embodiment may be used.

A known method can be used for covering the conductor 11 with the covering layer 12 . For example, the coating layer 12 can be formed by a general extrusion method. As the extruder used in the extrusion molding method, for example, a single-screw extruder or a twin-screw extruder having a screw, a breaker plate, a crosshead, a distributor, a nipple and a die can be used.

When producing the resin composition that constitutes the coating layer 12, an ethylene copolymer resin, a flame retardant, and an achromatic pigment are put into an extruder set to a temperature at which the resin is sufficiently melted. At this time, if necessary, other ingredients such as antioxidants and processing aids are also added to the extruder. Then, the resin composition is melted and kneaded by a screw, and a constant amount is supplied to the crosshead through a breaker plate. The melted resin composition flows onto the circumference of the nipple by means of a distributor, and is extruded by means of a die while covering the circumference of the conductor 11, thereby obtaining the coating layer 12 covering the circumference of the conductor 11. can.

As described above, in the covered electric wire 10 of the present embodiment, the covering layer 12 can be formed by extrusion molding in the same manner as in the general resin composition for electric wires. In order to improve the strength of the coating layer 12, after the coating layer 12 is formed on the outer periphery of the conductor 11, the resin composition may be crosslinked by a method such as irradiation with radiation as described above.

[Wire Harness]
A wire harness according to this embodiment includes a covered electric wire 10 . The resin composition according to the above embodiment has sufficient heat resistance life, flame retardancy and bleeding resistance. Therefore, the covered electric wire 10 having the covering layer 12 made of such a resin composition can be preferably used as a wire harness in the engine room of an automobile, for example.

EXAMPLES Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

A pure copper conductor (stranded wire) having a cross-sectional area of 3.0 mm ² was prepared as a metal conductor. Then, the conductor was coated with a resin composition having a formulation (unit: parts by mass) shown in Tables 1 and 2 to prepare a coated electric wire. Specifically, the conductor was coated with the resin composition at a temperature of about 140° C. to 180° C. using an extrusion coating apparatus for electric wire manufacturing having a screw diameter of 40 mm. The melt-kneading temperature of the resin composition and the temperature of the resin immediately after coming out of the extrusion coating apparatus were about 140°C. The extrusion coating apparatus was adjusted so that the standard thickness of the coating layer after coating was 0.65 mm. Further, the resin composition constituting the coating layer was crosslinked by electron beam irradiation under the conditions of 750 kV×160 kGy.

(ethylene copolymer resin)
ZE708 manufactured by Ube Maruzen Polyethylene Co., Ltd., ethylene-ethyl acrylate copolymer (EEA)

(Flame retardants)
Kisuma (registered trademark) 5AL manufactured by Kyowa Chemical Industry Co., Ltd., stearic acid surface-treated magnesium hydroxide, refractive index 1.57

(achromatic pigment)
(1) Zinc oxide Zinc oxide manufactured by Sakai Chemical Industry Co., Ltd., refractive index 2.00
(2) Titanium dioxide Typaque (registered trademark) CR-63 manufactured by Ishihara Sangyo Co., Ltd., refractive index 2.70
(3) Barium sulfate B-55 manufactured by Sakai Chemical Industry Co., Ltd., refractive index 1.63

(Inorganic layered compound)
BYK-Chemie CLOISITE® 20, clay, refractive index 1.57

(Antioxidant for olefin)
Combination of (1) and (2) below (1) Hindered phenol AO-60 manufactured by ADEKA Co., Ltd.
(2) Thioether Sumilizer (registered trademark) TP-D manufactured by Sumitomo Chemical Co., Ltd.

[evaluation]
The properties of Examples and Comparative Examples were evaluated by the following methods. Evaluation results are shown in Tables 1 and 2.

(Heat aging resistance)
An aging test was performed on the coated wire by heating at a temperature of 150° C. for 3000 hours. After that, the coated wire was wound around a mandrel having an outer diameter 1.5 times that of the coated wire, and it was confirmed that the conductor portion of the wrapped coated wire was not exposed. At that time, for those in which the conductor portion was not exposed, a voltage of 1000 V was applied between the conductor of the coated wire and the outer peripheral surface of the coating layer for 1 minute, and the presence or absence of dielectric breakdown in the coating layer was visually examined. A withstand voltage test was performed by As a result, the case where the dielectric breakdown did not occur and the withstand voltage test was performed for more than 400 hours was evaluated as "good", and the case where the time was 400 hours or less was evaluated as "failed".

(Flame retardance)
In accordance with JIS K7201-2:2007 (Plastics-Test method for flammability by oxygen index-Part 2: Test at room temperature), measure the oxygen index of a resin composition with a thickness of 3 mm that has undergone a cross-linking treatment. Flammability was evaluated. When the oxygen index (OI) was 22.5 or more, it was evaluated as "good", and when it was less than 22.5, it was evaluated as "poor".

(exterior)
Based on the L*a*b* color space of JIS Z8781, using a standard illuminant D65, a cross-linked resin composition with a thickness of 3 mm and a reference sample before cross-linking were colorimetrically compared. Appearance was evaluated by a certain color difference ΔE (difference between L*, a*, b*). When the color difference ΔE was 6 or less, it was evaluated as "Good", and when it exceeded 6, it was evaluated as "Bad".

(Bleed resistance)
After a heating test was performed on the covered wire at a temperature of 40° C. for 168 hours, the surface of the covering layer was touched with a finger to evaluate bleeding resistance. The case where stickiness due to bleeding material was not observed on the surface of the coating layer was evaluated as "good", and the case where stickiness was observed was evaluated as "poor".

As shown in Table 1, the resin compositions according to Examples 1 to 6 were excellent in heat aging resistance, flame retardancy, appearance and bleeding resistance. From these results, it is presumed that the resin compositions according to Examples 1 to 6 have sufficient heat resistance life, flame retardancy, and bleed resistance as coating layers for electric wires.

On the other hand, as shown in Table 2, the resin compositions according to Comparative Examples 1 to 3 were insufficient in at least one of heat aging resistance, flame retardancy and appearance. In Comparative Example 1, since no achromatic pigment was used, flame retardancy and appearance were rejected. In Comparative Example 2, the refractive index of the achromatic pigment was less than 2.0, so the appearance was rejected. In Comparative Example 3, an inorganic layered compound having a refractive index of 1.57 was used instead of the achromatic pigment, so the heat aging resistance, flame retardancy and appearance were rejected.

From these results, it can be seen that sufficient heat resistance life, flame retardancy, and bleed resistance can be obtained as a coating layer for an electric wire by blending a resin composition with a specific component and a specific composition.

Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications are possible within the scope of the gist of the present embodiment.

10 Covered Wire 11 Conductor 12 Coating Layer

Claims (9)

Containing an ethylene copolymer resin, a flame retardant, and an achromatic pigment having a refractive index of 2.0 or more,
The ethylene copolymer resin is crosslinked,
A resin composition containing 30 to 80 parts by mass of the flame retardant and 1 to 15 parts by mass of the achromatic pigment with respect to 100 parts by mass of the ethylene copolymer resin. The resin composition according to claim 1, wherein the flame retardant is magnesium hydroxide. 3. The resin composition according to claim 1, wherein said achromatic pigment contains at least one selected from zinc oxide and titanium dioxide. The resin composition according to any one of claims 1 to 3, wherein the achromatic pigment is zinc oxide, and contains 3 to 15 parts by mass of zinc oxide with respect to 100 parts by mass of the ethylene copolymer resin. thing. The resin composition according to any one of claims 1 to 3, wherein the achromatic pigment is titanium dioxide, and contains 1 to 3 parts by mass of titanium dioxide with respect to 100 parts by mass of the ethylene copolymer resin. thing. 5. The ethylene copolymer resin contains at least one selected from the group consisting of ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer and ethylene-butyl acrylate copolymer. The resin composition according to any one of. 7. The resin composition according to any one of claims 1 to 6, wherein a color difference ΔE between a sample after cross-linking treatment and a reference sample before cross-linking treatment is 6 or less. a conductor;
A coating layer that covers the conductor and contains the resin composition according to any one of claims 1 to 7;
covered wire. A wire harness comprising the covered electric wire according to claim 8 .

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