阅读说明：本技术 树脂组合物、护套电缆和线束 (Resin composition, sheathed cable, and wire harness ) 是由 泷皓宏 于 2021-04-29 设计创作，主要内容包括：树脂组合物包括树脂组分,该树脂组分包含乙烯-丙烯-二烯三元共聚物和乙烯丙烯酸酯橡胶中的至少一种以及乙烯-(甲基)丙烯酸酯共聚物。乙烯-(甲基)丙烯酸酯共聚物的含量相对于乙烯-丙烯-二烯三元共聚物和乙烯丙烯酸酯橡胶中的至少一种以及乙烯-(甲基)丙烯酸酯共聚物的总含量为35质量％以上且90质量％以下。树脂组合物的19％应变下的拉伸应力为2.0MPa以下,并且树脂组合物的断裂拉伸应力为10.3MPa以上。(The resin composition includes a resin component containing an ethylene- (meth) acrylate copolymer and at least one of an ethylene-propylene-diene terpolymer and an ethylene acrylate rubber. The content of the ethylene- (meth) acrylate copolymer is 35 mass% or more and 90 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The tensile stress at 19% strain of the resin composition is 2.0MPa or less, and the tensile stress at break of the resin composition is 10.3MPa or more.)

1. A resin composition comprising a resin component containing at least one of an ethylene-propylene-diene terpolymer and an ethylene acrylate rubber, and an ethylene- (meth) acrylate copolymer,

wherein the content of the ethylene- (meth) acrylate copolymer is 35% by mass or more and 90% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber,

the resin composition has a tensile stress at 19% strain of 2.0MPa or less, and

the resin composition has a tensile stress at break of 10.3MPa or more.

2. The resin composition according to claim 1, wherein a content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer is 24% by mass or more.

3. The resin composition according to claim 1 or 2, wherein the tensile stress at break of the ethylene- (meth) acrylate copolymer is 9MPa or more, and the flexural modulus of the ethylene- (meth) acrylate copolymer is 15MPa or less.

4. The resin composition according to any one of claims 1 to 3, further comprising a flame retardant in an amount of 80 parts by mass or less relative to 100 parts by mass of the resin component.

5. The resin composition according to any one of claims 1 to 4, having a heat resistance of 150 ℃ specified by JASO D624.

6. The resin composition according to any one of claims 1 to 5, wherein a content of the ethylene- (meth) acrylate copolymer is 40% by mass or more and 80% by mass or less with respect to a total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber.

7. The resin composition according to any one of claims 1 to 6, wherein a ratio of a weight average molecular weight to a number average molecular weight of the ethylene- (meth) acrylate copolymer is 5 or less.

8. The resin composition according to any one of claims 1 to 7, wherein a content of a (meth) acrylate contained in the ethylene- (meth) acrylate copolymer is 28% by mass or more and less than 30% by mass, a content of the ethylene- (meth) acrylate copolymer is 35% by mass or more and 80% by mass or less with respect to a total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber, and a ratio of a weight average molecular weight to a number average molecular weight of the ethylene- (meth) acrylate copolymer is 1 or more and 5 or less.

9. A jacketed cable, the jacketed cable comprising:

a conductor; and

a covering layer covering the conductor and including the resin composition according to any one of claims 1 to 8.

10. A wire harness comprising the sheathed cable according to claim 9.

Technical Field

The present invention relates to a resin composition, a sheathed cable and a wire harness.

Background

There is an increasing demand for an increase in battery capacity in order to increase the travel distance of the electric vehicle. In order to avoid an increase in charging time associated with an increase in battery capacity, it is necessary to increase the diameter of the conductor of the cable as a component of the wire harness. Since the volume of the battery increases as the capacity of the battery increases, the space occupied by the battery pack in the vehicle tends to increase. Therefore, the cable should be designed to be flexibly bent and routed in a narrow and short path.

Silicone rubber cables comprising conductors covered with a flexible silicone rubber insulation are commonly used in narrow and short paths. Silicone rubber is relatively expensive compared to commonly used insulating materials such as polyvinyl chloride, polypropylene and polyethylene. Further, in comparison with a manufacturing method of an insulating material that is generally used, it is necessary to additionally use a specific device to manufacture a silicone rubber cable, such as a hot air device for vulcanization after covering a conductor with silicone rubber by extrusion molding. Practical use cases do not always require the use of parts such as silicone rubber cables that are required to have a high level of heat resistance (200 ℃ x 10000 hours). Instead, various cables other than the silicone rubber cable are disclosed.

JP2008-84833a discloses a flexible non-halogen cable in which a conductor including a plurality of twisted wires is covered with an insulator. The wire has a diameter of 0.12mm to 0.31 mm. An insulator is obtained such that the resin component material and the metal hydroxide are mixed to form a sheath material, and the conductor is covered with the sheath material and then crosslinked to form a crosslinked resin composition. A resin composition material is obtained such that an ethylene copolymer as a main component containing oxygen in the molecular structure and containing 25 to 40 mass% of a vinyl monomer other than vinyl acetate is mixed together with an elastomer as a sub-component.

JP2016-173991a discloses a cable comprising a conductor composed of a plurality of conductive wires having a diameter of 0.15mm or more and 0.5mm or less, the periphery of the conductor being covered with an insulating resin containing a flame retardant. The insulating resin includes a copolymer A of an olefin and a comonomer having polarity, or a mixture of the copolymer A and a copolymer B of an olefin and an alpha-olefin. The ratio of the diameter of the cable to the diameter of the conductor is 1.15 or more and 1.40 or less, and the secant modulus in which the insulating resin is crosslinked is 10MPa or more and 50MPa or less.

Disclosure of Invention

The flexible non-halogen electric wire disclosed in JP2008-84833a and the cable disclosed in JP2016-173991a are each not sufficiently high in flexibility as compared with silicone rubber. As the thickness of the coated layer decreases and as the diameter of the conductor's wire decreases, the flexibility can increase. However, in view of the manufacturing cost, reduction of the wire diameter is not practical. Furthermore, the cover layer of the cable has strength and heat resistance in addition to flexibility.

In order to solve the above conventional problems, the present invention provides a resin composition having flexibility, strength and heat resistance sufficient for a covering layer of a cable, and provides a sheathed cable and a wire harness using the resin composition.

A resin composition according to an aspect of the present invention includes a resin component including an ethylene- (meth) acrylate copolymer and at least one of an ethylene-propylene-diene terpolymer and an ethylene acrylate rubber. The content of the ethylene- (meth) acrylate copolymer is 35 mass% or more and 90 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The tensile stress at 19% strain of the resin composition is 2.0MPa or less, and the tensile stress at break of the resin composition is 10.3MPa or more.

The content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer may be 24% by mass or more.

The tensile stress at break of the ethylene- (meth) acrylate copolymer may be 9MPa or more, and the flexural modulus of the ethylene- (meth) acrylate copolymer may be 15MPa or less.

The resin composition may further include 80 parts by mass or less of a flame retardant with respect to 100 parts by mass of the resin component.

The resin composition may have a heat resistance of 150 ℃ as defined in JASO D624.

The content of the ethylene- (meth) acrylate copolymer may be 40 mass% or more and 80 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber.

The ratio of the weight average molecular weight to the number average molecular weight of the ethylene- (meth) acrylate copolymer may be 5 or less.

The content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer may be 28% by mass or more and 30% by mass or less, the content of the ethylene- (meth) acrylate copolymer may be 35% by mass or more and 80% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber, and the ratio of the weight average molecular weight to the number average molecular weight of the ethylene- (meth) acrylate copolymer may be 1 or more and 5 or less.

A jacketed cable according to another aspect of the present invention includes a conductor and a covering layer covering the conductor and containing a resin component.

A wire harness according to still another aspect of the present invention includes a sheathed cable.

The present invention can provide a resin composition having flexibility, strength and heat resistance sufficient for a covering layer of a cable, and provide a sheathed cable and a wire harness using the resin composition.

Drawings

Fig. 1 is a schematic sectional view showing an example of a sheathed cable according to the present embodiment.

Detailed Description

The resin composition, the sheathed cable and the wire harness according to the present embodiment are described in detail below with reference to the drawings. The dimensional ratios of the elements in the drawings are exaggerated for illustrative purposes and are not necessarily drawn to scale.

[ resin composition ]

The resin composition contained in the covering layer of the jacketed cable is required to have high flexibility. It was found by the analysis that the sheathed cable had sufficient flexibility in actual use when the tensile stress at 19% strain of the resin composition was set to a predetermined value or less while, for example, taking into account the radius of the sheathed cable and the case where the sheathed cable was bent with a predetermined curvature. Therefore, the resin composition according to the present embodiment is configured such that the tensile stress at 19% strain is set to 2.0MPa or less. The flexibility of the resin composition can be improved by setting the tensile stress at 19% strain of the resin composition to 2.0MPa or less. The tensile stress at 19% strain is preferably 1.5MPa or less to approximate the flexibility of silicone rubber. Since the flexibility becomes higher as the tensile stress at 19% strain becomes smaller, the tensile stress at 19% strain may be set to 0.1MPa or more, and the lower limit of the tensile stress at 19% strain may be appropriately determined. The tensile stress at 19% strain can be measured according to JIS K7161-1:2014 (plastics-determination of tensile Property-part 1: general principle).

The resin composition preferably has a type a durometer hardness of 75 or less. Setting the type a durometer hardness of the resin composition to 75 or less can reduce the flexibility of the resin composition. The type A durometer hardness can be measured according to JIS K7215:1986 (test method for durometer hardness of plastics).

The resin composition contained in the covering layer of the jacketed cable is also required to have high hardness. The tensile stress at break of the resin composition is set to 10.3MPa or more. Setting the tensile stress at break of the resin composition to 10.3MPa or more can ensure sufficient strength when the resin composition is used for a covering layer of a jacketed cable. Since the strength of the resin composition is higher as the tensile stress at break is larger, the tensile stress at break may be set to 25MPa or less, or may be set to 20MPa or less, and the upper limit of the tensile stress at break may be appropriately determined. The tensile stress at break can be measured according to JIS K7161-1: 2014.

The resin composition contained in the covering layer of the jacketed cable is further required to have long-term heat resistance. The resin composition preferably has heat resistance of 150 ℃ specified in japanese automobile standards organization JASO D624. In particular, the elongation of the resin composition when heated at 150 ℃ for 10000 hours is preferably 100% or less. The resin composition having heat resistance as described above can be used for a covering layer of a sheathed cable in a high temperature environment including a case of use in an automobile.

(resin component)

The resin composition includes a resin component. The resin component contains an ethylene- (meth) acrylate copolymer and at least one of an ethylene-propylene-diene terpolymer (EPDM) and an ethylene acrylate rubber (AEM). As used herein, (meth) acrylate refers to at least one of acrylate and methacrylate.

(ethylene- (meth) acrylate copolymer)

The ethylene- (meth) acrylate copolymer is a copolymer obtained by polymerizing a monomer component containing ethylene with (meth) acrylate. An ethylene- (meth) acrylate copolymer can be obtained by polymerizing a monomer component containing ethylene with a (meth) acrylate.

The ethylene- (meth) acrylate copolymer can be obtained by a known polymerization reaction, and can be polymerized by tubular polymerization using a tubular polymerization reactor, or can be polymerized by autoclave polymerization using an autoclave polymerization reactor. In order to increase the tensile stress at 19% strain, the ethylene- (meth) acrylate copolymer is preferably polymerized by tubular polymerization.

The number average molecular weight Mn of the ethylene- (meth) acrylate copolymer may be, for example, 14000 or more, 15000 or more, 16000 or more, or 17000 or more. The number average molecular weight Mn of the ethylene- (meth) acrylate copolymer may be, for example, 22000 or less, 21000 or less or 20000 or less.

The weight average molecular weight Mw of the ethylene- (meth) acrylate copolymer may be, for example, 50000 or more, 60000 or more, or 70000 or more. The weight average molecular weight Mw of the ethylene- (meth) acrylate copolymer may be, for example, 120000 or less, 110000 or less, 100000 or less, or 90000 or less.

The ratio of Mw to Mn (Mw/Mn) of the ethylene- (meth) acrylate copolymer is preferably 1 or more and 6 or less. Setting the ratio Mw/Mn within this range can improve the tensile stress at break and the flexibility of the ethylene- (meth) acrylate copolymer. The Mw/Mn ratio may be 2 or more or 3 or more. The Mw/Mn ratio may be 5 or less.

For example, the (meth) acrylate includes at least one (meth) acrylate selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

Specific examples of the ethylene- (meth) acrylate copolymer include, but are not limited to, ethylene-methyl methacrylate copolymer (EMMA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA). These ethylene- (meth) acrylate copolymers may be used alone, or two or more of them may be used in combination. The ethylene- (meth) acrylate copolymer may, but need not, be modified with, for example, maleic acid and maleic anhydride. In order to secure heat resistance, the ethylene- (meth) acrylate copolymer is preferably at least one selected from the group consisting of ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA). In order to further improve the heat resistance, the ethylene- (meth) acrylate copolymer is more preferably at least one of an ethylene-methyl acrylate copolymer (EMA) and an ethylene-ethyl acrylate copolymer (EEA).

The ethylene- (meth) acrylate copolymer may include a small amount of ethylene and a monomer component other than (meth) acrylate. The total content of ethylene and (meth) acrylate ester contained in the ethylene- (meth) acrylate ester copolymer is preferably 80% by mass or more, more preferably 90% by mass or more. The total content of ethylene and (meth) acrylate contained in the ethylene- (meth) acrylate copolymer is more preferably 95% by mass or more.

The content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer is preferably 24% by mass or more. Setting the content of the (meth) acrylate to 24 mass% or more enables flexibility to be still exhibited with a small addition amount of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber, thereby reducing the addition amount of the additive sufficient to ensure the intended heat resistance. Since the addition amounts of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber can be reduced, the formability of the jacketed cable can be improved. The content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer is more preferably set to 28 mass% or more. The content of the (meth) acrylate contained in the ethylene- (meth) acrylate copolymer may be set to 40% by mass or less, or 35% by mass or less, and the upper limit of the content of the (meth) acrylate may be appropriately determined.

The ethylene content contained in the ethylene- (meth) acrylate copolymer is preferably, but not necessarily, set to 55% by mass or more and 75% by mass or less, and more preferably 65% by mass or more and 72% by mass or less. Setting the content of ethylene contained in the ethylene- (meth) acrylate copolymer to such a range can improve the mechanical characteristics of the sheathed cable as described below.

The ethylene- (meth) acrylate copolymer may have a flexural modulus (flexural elastic modulus) of 15MPa or less. The use of the ethylene- (meth) acrylate copolymer having such a flexural modulus can increase the possibility of improving the flexibility of the resin composition. The ethylene- (meth) acrylate copolymer may have a tensile stress at break of 9MPa or more. The flexural modulus of the ethylene- (meth) acrylate copolymer can be measured according to ISO178, ASTM D790 or JIS K7171: 2016. The tensile stress at break can be measured according to JIS K7161-1: 2014.

(ethylene-propylene-diene terpolymer)

Ethylene-propylene-diene terpolymers (EPDM) are rubbery copolymers of ethylene, propylene and a diene. The physical properties of the ethylene-propylene-diene terpolymer are controlled mainly by the amount of ethylene and the amount of diene. The lower the amount of ethylene, the lower the hardness (softer) and the greater the amount of diene, the lower the permanent compression strain. The content of ethylene contained in the ethylene-propylene-diene terpolymer is preferably, but not necessarily, set to 70 mass% or less in view of improvement in flexibility. The content of the diene contained in the ethylene-propylene-diene terpolymer is preferably, but not necessarily, set to 7 mass% or less in view of improvement in heat resistance. The content of diene set to 7 mass% or less as described above is also referred to as the amount of medium diene (amount of medium diene).

The ethylene-propylene-diene terpolymer may comprise oils such as mineral oil, paraffinic oil, and naphthenic oil. The Mooney viscosity of the ethylene-propylene-diene terpolymer is preferably 60ML (1+4) at 125 ℃ or less, wherein 60M means the Mooney viscosity and L means that the rotor has an L-shape, (1+4) means a preheating time of one minute and a rotor rotation time of four minutes, and 125 ℃ is a test temperature. The Mooney viscosity can be measured according to JIS K6300-1:2013 (rubber, unvulcanized-physical properties-part 1: Mooney viscosity and prevulcanized properties determined by means of a Mooney viscometer).

(ethylene acrylic acid ester rubber)

Ethylene acrylate rubber (AEM) is a rubbery copolymer of ethylene with ethyl acrylate or another acrylate. In view of flexibility, the shore a hardness of at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber is preferably, but not necessarily, set to 70 or less.

The resin component may contain a resin other than the ethylene- (meth) acrylate copolymer, the ethylene-propylene-diene terpolymer, and the ethylene acrylate rubber. The resin component may comprise, for example, a polyolefin. Polyolefins are polymers of olefin-containing monomers. The polyolefin may be a copolymer of an alpha olefin and an olefin other than the alpha olefin. The α -olefin may be at least one monomer selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. The polyolefin may be at least one resin selected from the group consisting of High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), polypropylene (PP), and ethylene-propylene block copolymer (EPBC).

The content of the resin component in the resin composition may be 50 mass% or more or 60 mass% or more. The content of the resin component in the resin composition may be 90% by mass or less, 80% by mass or less, or 70% by mass or less.

The total content of the ethylene- (meth) acrylate copolymer, the ethylene-propylene-diene terpolymer, and the ethylene acrylic rubber in the resin component may be 80 mass% or more or 90 mass% or more.

The content of the ethylene- (meth) acrylate copolymer is 35 mass% or more and 90 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. Setting the content of the ethylene- (meth) acrylate copolymer to 35% by mass or more can improve the heat resistance of the resin composition, and can further avoid deformation of an extrusion-molded article when the resin composition is extrusion-molded to manufacture a sheathed cable. The content of the ethylene- (meth) acrylate copolymer is preferably set to 40% by mass or more. Setting the content of the ethylene- (meth) acrylate copolymer to 90% by mass or less can improve flexibility and/or strength. The content of the ethylene- (meth) acrylate copolymer is preferably 80% by mass or less. That is, the content of the ethylene- (meth) acrylate copolymer is preferably 40 mass% or more and 80 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The content of the ethylene- (meth) acrylate copolymer is more preferably 70% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber.

The content of the (meth) acrylate in the ethylene- (meth) acrylate copolymer is preferably 24% by mass or more and 26% by mass or less, and the content of the ethylene- (meth) acrylate copolymer is preferably 35% by mass or more and 60% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber.

The content of the (meth) acrylate in the ethylene- (meth) acrylate copolymer is preferably 28% by mass or more and less than 30% by mass, the content of the ethylene- (meth) acrylate copolymer is preferably 71% by mass or more and 90% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber, and the Mw/Mn ratio of the ethylene- (meth) acrylate copolymer is preferably 5 or more and 10 or less. In this case, the content of the ethylene- (meth) acrylate copolymer may be 75 mass% or more, or may be 85 mass% or less, with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The ethylene- (meth) acrylate copolymer may have an Mw/Mn ratio of 6 or more. The ethylene- (meth) acrylate copolymer may have an Mw/Mn ratio of 9 or less or 8 or less.

The content of the (meth) acrylate in the ethylene- (meth) acrylate copolymer is preferably 28% by mass or more and less than 30% by mass, the content of the ethylene- (meth) acrylate copolymer is preferably 35% by mass or more and 80% by mass or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber, and the Mw/Mn ratio of the ethylene- (meth) acrylate copolymer is preferably 1 or more and 6 or less. In this case, the content of the ethylene- (meth) acrylate copolymer may be 40% by mass or more with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The ethylene- (meth) acrylate copolymer may have an Mw/Mn ratio of 2 or more or 3 or more. The ethylene- (meth) acrylate copolymer may have an Mw/Mn ratio of 5 or less.

(flame retardant)

The resin composition may include a flame retardant to improve flame retardancy. The resin composition preferably contains 80 parts by mass or less of a flame retardant with respect to 100 parts by mass of the resin component. Setting the content of the flame retardant to less than 80 parts by mass can improve the flexibility of the resin composition. In view of flexibility, the content of the flame retardant is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less, when the content of the resin component is 100 parts by mass. In view of flame retardancy, the content of the flame retardant is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 30 parts by mass or more, when the content of the resin component is 100 parts by mass.

The flame retardant may be of any type capable of imparting flame retardancy to the resin composition. For example, the flame retardant may include at least one of an organic flame retardant and an inorganic flame retardant. For example, the organic flame retardant may include at least one or more flame retardants selected from the group consisting of halogen flame retardants, phosphorus flame retardants, and nitrogen flame retardants. For example, the inorganic flame retardant may include at least one of a metal hydroxide and an antimony flame retardant. For example, the metal hydroxide may include at least one of magnesium hydroxide and aluminum hydroxide. For example, the antimony flame retardant may comprise antimony trioxide.

The halogen flame retardant is capable of trapping hydroxyl radicals which promote combustion of the thermoplastic and suppressing combustion of the resin composition. For example, the halogen flame retardant may be a compound in which at least one or more halogens are substituted with an organic compound. For example, the halogen flame retardant may include at least one or more flame retardants selected from the group consisting of fluorine flame retardants, chlorinated flame retardants, brominated flame retardants, and iodinated flame retardants. The halogen flame retardant is preferably a brominated flame retardant or a chlorinated flame retardant, and more preferably a brominated flame retardant.

The chlorinated flame retardant may include at least one flame retardant selected from the group consisting of chlorinated polyethylene, chlorinated paraffin, and perfluorocyclopentadecane.

The brominated flame retardant may include, for example, at least one flame retardant selected from the group consisting of: 1, 2-bis (bromophenyl) ethane, 1, 2-bis (pentabromophenyl) ethane, hexabromobenzene, ethylenebis-dibromonorbornanedicarboximide, ethylenebis-tetrabromophthalimide, tetrabromobisphenol S, tris (2, 3-dibromopropyl-1) isocyanurate, Hexabromocyclododecane (HBCD), octabromophenyl ether, tetrabromobisphenol A (TBA), TBA epoxy oligomer or polymer, TBA-bis (2, 3-dibromopropyl ether), decabromodiphenyl ether, polydibromophenylene ether, bis (tribromophenoxy) ethane, ethylenebis (pentabromophenyl), dibromoethyl-dibromocyclohexane, dibromoneopentyl glycol, tribromophenol allyl ether, tetradecbromodiphenoxybenzene, 2-bis (4-hydroxy-3, 5-dibromophenyl) propane, 2, 2-bis (4-hydroxyethoxy-3, 5-dibromophenyl) propane, pentabromophenol, pentabromotoluene, pentabromodiphenyl ether, hexabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether, octabromodiphenyl ether, dibromoneopentyl glycol tetracarbonate, bis (tribromophenyl) fumaramide, and N-methylhexabromoaniline.

For example, the phosphorus flame retardant may include at least one or more flame retardants selected from the group consisting of phosphate esters, condensed phosphate esters, cyclic phosphorus compounds, and red phosphorus.

For example, the nitrogen flame retardant may include at least one of a guanidinium urea flame retardant such as guanidinium urea phosphate or a melamine compound such as melamine cyanurate.

The flame retardant preferably includes a brominated flame retardant and an antimony flame retardant, and more preferably includes ethylene bis (pentabromophenyl) and antimony trioxide. The use of the flame retardant as described above in the resin composition according to the present embodiment can improve flame retardancy at a small content.

The content of the brominated flame retardant is preferably set in the range of 50 to 80 mass%, and more preferably in the range of 60 to 70 mass%, with respect to the total content of the flame retardants. The content of the antimony flame retardant is preferably set in the range of 20 to 50 mass%, and more preferably in the range of 30 to 40 mass%, with respect to the total content of the flame retardants. The ratio of the brominated flame retardant to the antimony flame retardant (brominated flame retardant/antimony flame retardant) is preferably set in the range of 1 to 4, and more preferably in the range of 3/2 to 7/3.

In the case where the resin composition of the present embodiment further includes an additive, the content of the additive is preferably 25 parts by mass or less when the content of the resin component is 100 parts by mass. Setting the content of the additive to 25 parts by mass or less can improve the flexibility of the resin composition.

The content of the flame retardant and the additive other than the flame retardant in the resin composition of the present embodiment is preferably less than 70 parts by mass when the content of the resin component is 100 parts by mass. Setting the content of the flame retardant and the additives other than the flame retardant to less than 70 parts by mass can improve the flexibility of the resin composition. The content of the flame retardant and the additive other than the flame retardant in the resin composition of the present embodiment is more preferably less than 60 parts by mass when the content of the resin component is 100 parts by mass.

Examples of the additives include crosslinking agents, crosslinking aids, antioxidants, processing aids, plasticizers, metal deactivators, fillers, reinforcing agents, UV absorbers, stabilizers, pigments, dyes, colorants, electrostatic agents, and foaming agents.

Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants and sulfur antioxidants.

Examples of processing aids include mineral oils such as paraffinic and naphthenic oils added to rubber materials.

The resin composition is prepared so that the above resin components are melt-kneaded, which can be carried out by a known method. For example, the resin composition can be obtained by premixing with a high-speed mixing device such as a Henschel mixer and kneading by a known kneader such as a Banbury mixer, a kneader and a roll mill.

The resin component in this embodiment may be crosslinked. Crosslinking the ethylene- (meth) acrylate copolymer, the ethylene-propylene-diene terpolymer, and the ethylene acrylate rubber can improve the heat resistance of the resin composition. Although the crosslinking method of the resin component may be appropriately determined, the resin component may be subjected to radiation to perform crosslinking, or the resin component may be crosslinked using a crosslinking agent contained in the resin composition. The resin component is preferably crosslinked by irradiation.

For example, the radiation used for crosslinking may be gamma rays or electron beams. Subjecting the cover layer to radiation generates free radicals in the molecules to form cross-links between the respective molecules.

The crosslinking agent used herein may be, for example, an organic peroxide. The crosslinking agent may be at least one selected from the group consisting of: dicumyl peroxide, di-t-butyl peroxide, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexyne-3, 1, 3-bis (t-butylperoxyisopropyl) benzene, 1-bis (t-butylperoxy) -3,3, 5-trimethylcyclohexane, n-butyl-4, 4-bis (t-butylperoxy) valerate, benzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, t-butyl benzoate, t-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and t-butylcumyl peroxide. The crosslinking agent may be used alone, or two or more of them may be used in combination. The content of the crosslinking agent in the resin composition is preferably set in the range of 0.05 parts by mass to 0.10 parts by mass with respect to 100 parts by mass of the resin component.

The resin composition may further include a crosslinking aid in addition to the crosslinking agent to improve crosslinking efficiency. Polyfunctional compounds can be used as crosslinking aids. The crosslinking assistant may be, for example, at least one compound selected from the group consisting of an acrylate compound, a methacrylate compound, an allyl compound, and a vinyl compound. These polyfunctional compounds may be used alone, or may be used in combination. The compound to be used is preferably trimethylolpropane trimethacrylate due to the high affinity of the resin component.

The content of the crosslinking assistant in the resin composition is preferably set in the range of 0.1 to 5 parts by mass, more preferably in the range of 0.8 to 2 parts by mass, relative to 100 parts by mass of the resin component. Setting the content of the crosslinking assistant to the above range can improve the heat resistance, processability and leakage resistance of the resin composition.

As described above, the resin composition includes the resin component including the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The content of the ethylene- (meth) acrylate copolymer is 35 mass% or more and 90 mass% or less with respect to the total content of the ethylene- (meth) acrylate copolymer and at least one of the ethylene-propylene-diene terpolymer and the ethylene acrylate rubber. The resin composition has a tensile stress at 19% strain of 2.0MPa or less and a tensile stress at break of 10.3MPa or more. The above resin composition can ensure sufficient flexibility, strength and heat resistance for a covering layer of a cable.

[ sheathed cable ]

Fig. 1 is a sectional view showing an example of a sheathed cable 10 according to the present embodiment. As shown in fig. 1, a jacketed cable 10 according to the present embodiment includes a conductor 11 and a covering layer 12, the covering layer 12 covering the conductor 11 and containing the resin composition according to the above-described embodiment. The resin composition according to the present embodiment has sufficient flexibility, strength, and heat resistance. The jacketed cable 10 including the cover layer 12 is suitable for use in, for example, automobiles.

The conductor 11 may be composed of a single wire, or may be a stranded wire including a plurality of wires bundled together. The conductor 11 may be composed of a single wire, or may be a composite stranded wire including a plurality of stranded wires bundled together. Conductor 11 preferably has a structure and dimensions specified by at least one of JASO D624 and ISO 6722-1.

The diameter of the conductor 11 is preferably, but not necessarily, set to 4.0mm or more, and more preferably 5.0mm or more. Setting the diameter of the conductor 11 to this size can reduce the resistance of the conductor 11 and shorten the charging time when, for example, the battery has a large capacity. The diameter of the conductor 11 is preferably, but not necessarily, set to 25mm or less, more preferably 20mm or less. Setting the diameter of the conductor 11 to this size can facilitate the routing of the sheathed cable 10 in a narrow and short path.

The diameter of the wire is preferably, but not necessarily, set to 0.1mm or more, and more preferably 0.2mm or more. Setting the diameter of the wire to this size can avoid the cutting of the wire. The diameter of the wire is preferably, but not necessarily, set to 0.5mm or less, and more preferably 0.4mm or less. Setting the diameter of the electric wire to this size can facilitate the wiring of the sheathed cable 10 in a narrow and short path.

The material for the conductor 11 is preferably, but not necessarily, at least one conductive metal material selected from, for example, copper, a copper alloy, aluminum, and an aluminum alloy.

The thickness of the cover layer 12 is preferably, but not necessarily, set to 0.5mm or more, more preferably 0.65mm or more. Setting the thickness of the covering layer 12 to this size can effectively protect the conductor 11. The thickness of the cover layer 12 is preferably, but not necessarily, set to 2.0mm or less, and more preferably 1.85mm or less. Setting the thickness of the covering layer 12 to this dimension can facilitate the routing of the sheathed cable 10 in a narrow and short path.

The jacketed cable 10 may also include a shield layer covering the cover layer 12 and a jacket layer further covering the shield layer. The shielding layer can prevent unnecessary electromagnetic waves from being emitted from the conductor 11. The shielding layer can be formed so that a conductive metal foil, a metal-containing foil, or a metal wire (metal conductor) is braided in a mesh shape. The sheath layer can effectively protect and bind the shielding layer. The sheath layer used herein may be, but need not be, an olefin resin such as polyethylene, or a resin composition according to the embodiment.

The conductor 11 may be covered by a cover layer 12 by a known method. For example, the cover layer 12 may be formed by a general extrusion molding method. The extruder used for the extrusion molding method may be a single screw extruder or a twin screw extruder having a screw, a breaker plate, a crosshead (crosshead), a distributor, a nozzle, and a die.

When manufactured, the resin composition for the cover layer 12 is put into an extruder set to a temperature sufficient to melt the resin. At the same time, other components such as flame retardants, antioxidants and processing aids are also placed in the extruder as needed. The resin composition is melted and kneaded by a screw, and a predetermined amount is supplied to a crosshead through a breaker plate. Then, the molten resin composition is flowed into the periphery of the nozzle through a dispenser and extruded through a die in a state of covering the outer periphery of the conductor 11 to obtain a covering layer 12 covering the outer periphery of the conductor 11.

Therefore, the sheathed cable 10 according to the present embodiment can be provided with the covering layer 12 by extrusion molding in a manner similar to a general resin composition for a cable. In order to improve the strength of the covering layer 12, after the covering layer 12 is formed on the outer periphery of the conductor 11, the resin composition may be crosslinked by the above-described method, for example, radiation.

[ Wiring harness ]

The wire harness according to the present embodiment includes a sheathed cable 10. The resin composition according to the above embodiment has sufficient flexibility, strength, and heat resistance. The sheathed cable 10 comprising the covering layer 12 of the resin composition as described above can be suitably used for, for example, a wiring harness of an automobile.

[ examples ]

The present embodiment is described in more detail below with reference to examples and comparative examples, but is not limited to these examples.

Preparation has a thickness of 3.0mm²A pure copper conductor (stranded wire) of a cross-sectional area is used as the metal conductor. The conductor was covered with a resin composition having a composition (unit: parts by mass) shown in tables 1 to 4 to manufacture a jacketed cable. The conductor is covered by an extrusion covering device for cable manufacture having a screw diameter of 40mm under temperature conditions of about 140 to 180 ℃. The melt kneading temperature for the resin composition and the resin temperature immediately after the extrusion coating apparatus was removed were about 140 ℃. The extrusion coating apparatus was controlled so that the standard of the thickness of the coating layer after being coated was 0.65 mm. The jacketed cable was crosslinked at 750kV × 160 kGy.

(resin component)

(1) Ethylene-ethyl acrylate copolymer (EEA)

Ethyl Acrylate (EA) content: 20% by mass

DPDJ-9169 manufactured by NUC Corporation

(2) Ethylene-ethyl acrylate copolymer (EEA)

Ethyl Acrylate (EA) content: 25% by mass

NUC-6570 manufactured by NUC Corporation

(3) Ethylene-ethyl acrylate copolymer (EEA)

Ethyl Acrylate (EA) content: 30% by mass

EX4227 manufactured by Ube-Maruzen Polyethylene Co, Ltd

(4) Ethylene-methyl acrylate copolymer (EMA)

Methyl Acrylate (MA) content: 20% by mass

Elvaloi (registered trademark) AC 1820 manufactured by Du Pont-Mitsui Polychemicals Co., Ltd

(5) Ethylene-methyl acrylate copolymer (EMA)

Methyl Acrylate (MA) content: 25% by mass

Elvaoi (registered trademark) AC 1125 manufactured by Du Pont-Mitsui Polychemicals Co., Ltd

(6) Ethylene-methyl acrylate copolymer (EMA)

Methyl Acrylate (MA) content: 29% by mass

LOTRYL (registered trademark) 29MA03 manufactured by Arkema Inc

(7) Ethylene-methyl acrylate copolymer (EMA)

Methyl Acrylate (MA) content: 29% by mass

LOTRYL (registered trademark) 29MA03T manufactured by Arkema Inc

(8) Ethylene-propylene-diene terpolymers (EPDM)

NORDEL (registered trademark) IP4760P manufactured by The Dow Company

(9) Ethylene acrylate rubber (AEM)

Vamac (registered trademark) VMX2122 manufactured by Du Pont co

The resin component 29MA03 was polymerized by autoclave polymerization, and the resin component 29MA03T was polymerized by tubular polymerization. The resin component 29MA03 had a number average molecular weight Mn of 15555 and a weight average molecular weight Mw of 108163. The Mw/Mn ratio was 6.954. The resin component 29MA03T had a number average molecular weight Mn of 18199 and a weight average molecular weight Mw of 70533. The Mw/Mn ratio was 3.876.

(flame retardant)

(1) Brominated flame retardants

Ethylenebis (pentabromophenyl): 30 parts by mass

SAYTEX (registered trademark) 8010 manufactured by Albemarle Corporation

(2) Antimony flame retardant

Antimony trioxide: 10 parts by mass

PATOX (registered trademark) M manufactured by Nippon Seiko Co., Ltd

The content of the brominated flame retardant was set to 75 mass% and the content of the antimony flame retardant was set to 25 mass% with respect to the entire flame retardant. The ratio of brominated flame retardant to antimony flame retardant (brominated flame retardant/antimony flame retardant) was prepared as 3.

(antioxidant)

(1) ADK STAB (registered trademark) AO-20 manufactured by ADEKA CORPORATION: 12 parts by mass

(2) ADK STAB (registered trademark) AO-412S manufactured by ADEKA CORPORATION: 12 parts by mass

(processing aid)

Trimethylolpropane trimethacrylate (TMPT) was manufactured by Shin-Nakamura Chemical Co., Ltd

[ evaluation ]

Each of examples and comparative examples was evaluated by the following methods. The evaluation results are shown in the tables.

(hardness)

The conductor is removed from the jacketed cable after the cross-linking treatment to obtain a covering layer. The obtained resin sheet obtained by profiling the resin composition contained in the covering layer to have a thickness of 6mm was measured by a type a durometer according to JIS K7215: 1986. A resin sheet having a hardness of 75 or less is rated B (pass), and a resin sheet having a hardness of more than 75 is rated C (fail).

(tensile stress at 19% Strain)

The conductor is removed from the jacketed cable after the cross-linking treatment to obtain a covering layer. The tensile stress at 19% strain of the resin composition contained in the covering layer was measured according to JIS K7161-1:2014 to evaluate flexibility. A test sample was prepared such that the resin composition was formed into a resin sheet having a thickness of 1m, and then punched out into a sheet having a thickness of 1m in JIS K6251: 2017 (determination of rubber, vulcanized or thermoplastic-tensile stress-strain properties) of the specified dumbbell No. 3 shape. The tensile stress at 19% strain is measured at room temperature (23 ℃) at a test speed of 200 mm/min. A test sample with a tensile stress at 19% strain of 1.5MPa or less was rated a (good), a test sample with a tensile stress at 19% strain of more than 1.5MPa and 2.0MPa or less was rated B (pass), and a test sample with a tensile stress at 19% strain of more than 2.0MPa was rated C (fail).

(tensile stress at break)

The conductor is removed from the jacketed cable after the cross-linking treatment to obtain a covering layer. The tensile stress at break of the resin composition contained in the covering layer was measured in accordance with JIS K7161-1:2014 to evaluate flexibility. A test sample was prepared such that the resin composition was formed into a resin sheet having a thickness of 1mm, and then punched out into a sheet of JIS K6251: 2017 (determination of rubber, vulcanized or thermoplastic-tensile stress-strain properties) of the specified dumbbell No. 3 shape. The tensile stress at break was measured at room temperature (23 ℃) at a test speed of 200 mm/min. A test specimen having a tensile stress at break of 10.3MPa or more was rated as B (pass), and a test specimen having a tensile stress at break of less than 10.3MPa was rated as C (fail). The tensile stress at break of the ethylene- (meth) acrylate copolymer was also independently measured by the same method as described above. The case with a tensile stress at break above 9MPa was rated as B (pass) and the case with a tensile stress at break less than 9MPa was rated as C (fail).

(Heat resistance)

The heat resistance of the resin composition after the crosslinking treatment was measured according to JASO D624. Specifically, the elongation of the test sample when heated for a predetermined time is substituted into the Arrhenius equation, and the temperature at which the elongation of the test sample when heated for 10000 hours is 100% is estimated. Test samples were prepared such that the resin composition was formed into a resin sheet having a thickness of 1mm, and then punched out into a sheet of JIS K6251: 2017, and a dumbbell shape. The test specimen for measurement was heated to 5000 hours under heating at 160 ℃ to 190 ℃ in accordance with JIS K7212:1999 (determination of thermal stability of plastics-thermoplastics-oven method). The test sample was then removed from the oven and allowed to stand at room temperature (23 ℃) for 12 hours. The elongation was measured at room temperature (23 ℃) at a test speed of 200 mm/min. The test sample was rated as B (passed) when the temperature at which the elongation was 100% was 150 ℃ or more, and rated as C (failed) when the temperature was below 150 ℃.

(flexural modulus)

A test piece was prepared such that the ethylene- (meth) acrylate copolymer was press-molded and punched out to a size specified in JIS K7171(ISO178) to have a thickness of 4.0 mm. The punched test piece was then compressed at room temperature (23 ℃) at a test speed of 2.0mm/min, and the flexural modulus (elastic flexural modulus) was calculated according to the calculation method specified in JIS K7171, clause 3.11. The test piece having a flexural modulus of 15MPa or less was rated as B (pass), and the test piece having a flexural modulus of more than 15MPa was rated as C (fail).

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

As shown in table 1, the resin compositions of examples 1 to 10 exhibited high tensile stress at 19% strain, high tensile stress at break, and high heat resistance. From the respective results, it can be estimated that the resin compositions of examples 1 to 10 have flexibility, strength and heat resistance sufficient for covering layers of cables. As shown in tables 2 and 4, the resin compositions of comparative examples 1 to 23 respectively had results in which at least one of flexibility, strength, and heat resistance was unsatisfactory. The test results show that preparing a resin composition consisting of specific components and a specific composition can produce flexibility, strength and heat resistance sufficient for a covering layer of a cable. The evaluation results of examples 5 to 10 shown in table 1 also show that the ethylene- (meth) acrylate copolymer can exhibit good effects with a content in a wide range of 40 to 80 parts by mass when obtained by tubular polymerization. The ethylene- (meth) acrylate copolymer can exhibit a better effect on tensile stress at 19% strain when having a content in the range of 40 parts by mass to 70 parts by mass.

It should be understood that the present embodiment described above is not intended to be limited to these descriptions, and various modifications may be made within the scope of the present embodiment.