Resin composition and coated wire

Abstract

To provide a resin composition which is excellent in flame retardancy and heat resistance, and can suppress moisture absorption and bleeding, without using a bromine-based flame retardant having a concern of an environmental regulation control.SOLUTION: A resin composition contains polyolefin, zeolite, an antioxidant, and a metal hydroxide, wherein the resin composition contains 0.1 pts.mass or more and 3.5 pts.mass or less of the zeolite with respect to 100 pts.mass of the polyolefin, and 1 pts.mass or more and 6.5 pts.mass or less of the antioxidant with respect to 100 pts.mass of the polyolefin, and a mass ratio of the zeolite to the antioxidant is 0.08 or more and 3 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin composition and a coated electric wire.

Background Art

[0002] Conventionally, it has been known to provide a coating layer formed of a resin composition containing a thermoplastic resin on a coated electric wire routed in an automobile. Further, a thermoplastic resin such as polyolefin is appropriately added with a flame retardant in order to impart flame retardancy suitable for practical use.

[0003] As a highly flame-retardant flame retardant, brominated flame retardants are known. Patent Document 1 discloses a resin composition containing a thermoplastic resin, a brominated flame retardant, and zeolite having a pore diameter of 8 Å or less.

[0004] On the other hand, as a flame retardant, non-brominated flame retardants such as metal hydroxides are also known. Patent Document 2 discloses a non-halogen electric wire in which a conductor is coated with a material containing a resin component and a metal hydroxide.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The resin composition described in Patent Document 1 maintains high flame retardancy and also has good heat resistance. However, among brominated flame retardants, there are substances regulated by environmental regulations such as polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE). Therefore, in the future, other brominated flame retardants may also be subject to environmental regulations. When environmental regulations are established, the use of resin compositions containing brominated flame retardants may be restricted.

[0007] Also, in the non-halogen wire described in Patent Document 2, in order to satisfy the flame retardancy equivalent to that of brominated flame retardants, it is necessary to fill a large amount of metal hydroxide. However, such metal hydroxides may accelerate the oxidative degradation of the resin component. Therefore, when a large amount of metal hydroxide is filled, the heat resistance of the resin composition may decrease.

[0008] The present invention has been made in view of the problems of such conventional technologies. The object of the present invention is to provide a resin composition and a coated wire that are excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using brominated flame retardants that are a concern in environmental regulations.

Means for Solving the Problems

[0009] The resin composition according to an aspect of the present invention contains a polyolefin, a zeolite, an antioxidant, and a metal hydroxide. The resin composition contains 0.1 part by mass or more and 3.5 parts by mass or less of zeolite with respect to 100 parts by mass of the polyolefin. The resin composition contains 1 part by mass or more and 6.5 parts by mass or less of the antioxidant with respect to 100 parts by mass of the polyolefin. The mass ratio of the zeolite to the antioxidant is 0.08 or more and 3 or less.

[0010] The coated wire according to another aspect of the present invention includes a conductor and a coating layer that coats the conductor and is formed of the above resin composition.

Effects of the Invention

[0011] According to the present invention, it is possible to provide a resin composition and a coated wire that are excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using brominated flame retardants that are a concern in environmental regulations.

Brief Description of the Drawings

[0012]

Figure 1

Mode for Carrying Out the Invention

[0013] 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.

[0014] [Resin Composition] The resin composition according to the present embodiment contains a polyolefin, a zeolite, an antioxidant, and a metal hydroxide. Hereinafter, each component will be described in detail.

[0015] (Polyolefin) Polyolefin is a resin obtained by polymerizing monomers of olefins or alkenes. The polyolefin may be, for example, a polymer obtained by polymerizing a monomer containing at least one of ethylene and propylene. Specifically, the polyolefin may contain at least one resin selected from the group consisting of, for example, polyethylene, ethylene copolymer, and polypropylene. Further, the polyolefin may be an olefin-based thermoplastic elastomer (TPO).

[0016] Polyethylene may contain at least one selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (VLDPE). Polyethylene may be a copolymer containing a small amount of comonomer. Polyethylene may be a homopolymer of an ethylene monomer, a copolymer of an ethylene monomer and an α-olefin monomer of 5 mol% or less, or a copolymer of an ethylene monomer and a non-olefin monomer of 1 mol% or less having only carbon, oxygen, or hydrogen atoms in the functional group.

[0017] The ethylene copolymer may be a polymer obtained by polymerizing two or more types of monomers. The ethylene copolymer may be a copolymer of an ethylene monomer and an olefin monomer other than the ethylene monomer in an amount exceeding 5 mol%, or a copolymer of an ethylene monomer and a non-olefin monomer in an amount exceeding 1 mol%. The ethylene copolymer may contain, for example, at least one selected from the group consisting of ethylene-butene copolymers, ethylene-octene copolymers, ethylene-vinyl ester copolymers, ethylene-α,β-unsaturated carboxylic acids, ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymers, ethylene-vinyl acetate copolymers (EVA), ethylene-methyl methacrylate copolymers (EMMA), ethylene-methyl acrylate copolymers (EMA), ethylene-ethyl acrylate copolymers (EEA), ethylene-butyl acrylate copolymers (EBA), and ethylene-vinyl acetate-ethyl acrylate copolymers.

[0018] Polypropylene may contain propylene as the main component and an α-olefin other than propylene. Here, the main component means that the propylene monomer accounts for 50% or more of the total monomers used for polymerizing polypropylene. Polypropylene may contain at least one of block copolymers and random copolymers. Polypropylene may contain at least one selected from the group consisting of propylene homopolymers, propylene-ethylene random copolymers, propylene-α-olefin random copolymers, and propylene·ethylene-α-olefin random copolymers.

[0019] The content of the polyolefin in the resin component contained in the resin composition may be 90% by mass or more, 95% by mass or more, 99% by mass or more, or 100% by mass.

[0020] The polyolefin may be crosslinked. By crosslinking the polyolefin, the mechanical properties of the resin composition can be improved. The polyolefin may contain, for example, at least one of polyethylene and ethylene copolymer. Such polyolefin is highly flexible and thus suitable for the coating layer of an electric wire.

[0021] (Zeolite) The resin composition contains zeolite. By adding zeolite to the resin composition, the heat resistance can be improved. Zeolite is a kind of aluminosilicate and can be represented by the general formula M x / n ·[(AlO2) x ·(SiO2) y ·zH2O. In the general formula, M is a cation with valence n, x + y is the number of tetrahedrons per unit cell, z is the number of moles of water, and y is a value larger than x. As cation species with valence 1, Li + , Na + , K + etc. can be mentioned. As cation species with valence 2, Ca 2+ , Mg 2+ , Ba 2+ etc. can be mentioned.

[0022] The resin composition contains 0.1 part by mass or more and 3.5 parts by mass or less of zeolite with respect to 100 parts by mass of the polyolefin. By setting the content of zeolite to 0.1 part by mass or more, the heat resistance can be improved. Also, by setting the content of zeolite to 3.5 parts by mass or less, moisture absorption by zeolite can be suppressed. The content of zeolite may be 0.3 part by mass or more, 0.5 part by mass or more, 1 part by mass or more, 1.5 parts by mass or more, 2 parts by mass or more, 2.5 parts by mass or more, or 3 parts by mass or more. Also, the content of zeolite may be 3 parts by mass or less, 2.5 parts by mass or less, 2 parts by mass or less, 1.5 parts by mass or less, 1 part by mass or less, 0.8 part by mass or less, or 0.5 part by mass or less.

[0023] Generally, zeolites are porous and have pores. Zeolites are known to have a molecular sieve effect and an ion exchange function because they can adsorb molecules smaller than the pore diameter, but molecules larger than the pore diameter cannot enter the pores. The pore diameter of zeolites is derived from the crystal structure of zeolites. The pore diameter of zeolites may be, for example, 1 Å or more and 10 Å or less. The pore diameter of zeolites may be 2 Å or more, 3 Å or more, 4 Å or more, 5 Å or more, 6 Å or more, 7 Å or more, or 8 Å or more. Also, the pore diameter of zeolites may be 9 Å or less, 8 Å or less, 7 Å or less, 6 Å or less, 5 Å or less, 4 Å or less, or 3 Å or less. The pore diameter of zeolites can be measured, for example, by the Horvath-Kawazoe method or the like.

[0024] The molar ratio of silica to alumina (SiO2 / Al2O3 ratio) in zeolites is not particularly limited. The silica / alumina ratio may be, for example, 1 or more and 10,000 or less. The silica / alumina ratio may be 2 or more, 5 or more, 20 or more, 80 or more, 500 or more, or 1000 or more. Also, the silica / alumina ratio may be 2000 or less, 1000 or less, 200 or less, 50 or less, 30 or less, 10 or less, or 4 or less.

[0025] The pore diameter of the zeolite is 6.5 Å or less, or the pore diameter of the zeolite is 6.6 Å or more and 9.0 Å or less, and the molar ratio of silica to alumina in the zeolite may be 10 or less. The resin composition containing such zeolites is particularly excellent in heat resistance.

[0026] Zeolites include natural zeolites, synthetic zeolites, and artificial zeolites. Natural zeolites are produced in nature and are often characterized by being inexpensive. Synthetic zeolites are made from highly pure chemical substances and are characterized by high purity. Artificial zeolites are made from unused resources such as coal ash as raw materials, and are characterized by being higher in purity compared to natural zeolites and less expensive compared to artificial zeolites. Among these, it is preferable that the zeolite is at least one of synthetic zeolites and artificial zeolites. These zeolites have a uniform structure compared to natural zeolites.

[0027] The structure of the zeolite is not particularly limited, and may be, for example, A-type, beta-type, MCM-22, ZSM-5, ferrierite, and mordenite.

[0028] The average particle size of the zeolite is not particularly limited, and may be 0.1 μm or more, 1 μm or more, or 5 μm or more. Also, the average particle size of the zeolite may be 50 μm or less, 30 μm or less, or 20 μm or less. The average particle size of the zeolite is a value calculated as the average value of the particle sizes of the particles observed in several to several tens of fields of view by observing the cross-section of the resin composition using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0029] The cation species of the zeolite is not particularly limited, and may be, for example, at least one selected from the group consisting of hydrogen ion (H + ), potassium ion (K + ), calcium ion (Ca 2+ ), and ammonium ion (NH4 + ).

[0030] (Antioxidant) The antioxidant suppresses the oxidative degradation of polyolefins and the like. As antioxidants, known antioxidants used in polyolefins can be used, such as radical chain inhibitors like phenolic antioxidants and amine antioxidants, peroxide decomposers like phosphorus-based antioxidants and sulfur-based antioxidants, and metal deactivators like hydrazine-based antioxidants and amine antioxidants. The antioxidant may be used alone or in combination of multiple types.

[0031] The resin composition contains 1 to 6.5 parts by mass of an antioxidant based on 100 parts by mass of polyolefin. By setting the content of the antioxidant to 1 part by mass or more, it is possible to suppress the degradation of polyolefins and the like due to oxidation. Also, by setting the content of the antioxidant to 6.5 parts by mass or less, bleed-out can be suppressed. Further, by setting the content of the antioxidant to 6.5 parts by mass or less, it is possible to suppress the antioxidant from reacting during the cross-linking treatment and reducing the cross-linking degree of the resin composition, or the smoke generation characteristics from deteriorating when the wire is energized. In this embodiment, since the heat resistance is improved by the addition of zeolite, it is expected that the effect can be exhibited with a smaller amount compared to the case of using the antioxidant alone. Also, the content of the antioxidant may be 6 parts by mass or less, 4 parts by mass or less, or 2 parts by mass or less.

[0032] The mass ratio of zeolite to the antioxidant (zeolite / antioxidant) is 0.08 or more and 3 or less. By setting the mass ratio of zeolite and the antioxidant within the above range, the heat resistance can be improved. The above mass ratio may be 0.1 or more, or 0.3 or more. Also, the above mass ratio may be 2 or less, 1 or less, or 0.7 or less.

[0033] (Metal hydroxide) The metal hydroxide functions as a flame retardant. Compared with brominated flame retardants, the metal hydroxide is less likely to be subject to environmental regulations. Therefore, in the resin composition according to this embodiment, the metal hydroxide is used as a flame retardant for the resin composition.

[0034] The metal hydroxide may contain at least one of a salt of a metal ion and a hydroxide ion and a hydrate of a metal oxide. The metal hydroxide may contain, for example, at least one selected from the group consisting of magnesium hydroxide (Mg(OH)2), aluminum hydroxide (Al(OH)3), calcium hydroxide (Ca(OH)2), basic magnesium carbonate (mMgCO3·Mg(OH)2·nH2O), hydrated aluminum silicate (aluminum silicate hydrate, Al2O3·3SiO2·nH2O), and hydrated magnesium silicate (magnesium silicate pentahydrate, Mg2Si3O8·5H2O). Specifically, the metal hydroxide may contain magnesium hydroxide.

[0035] These metal hydroxides are preferably surface-treated in consideration of their compatibility with the resin material, but can be used as long as the physical properties do not deteriorate without surface treatment. As the surface treatment of the metal hydroxide, it is preferably carried out using a silane coupling agent, a titanate coupling agent, a fatty acid such as stearic acid, or a metal salt of a fatty acid such as calcium stearate.

[0036] The resin composition may contain 40 to 130 parts by mass of the metal hydroxide with respect to 100 parts by mass of the polyolefin. In the resin composition according to the present embodiment, as described above, since the blending ratio of the zeolite and the antioxidant is optimized, the content of the metal hydroxide can be within the above range. Further, by setting the content of the metal hydroxide to 40 parts by mass or more, the flame retardancy can be further improved. Further, by setting the content of the metal hydroxide to 130 parts by mass or less, the hardness of the resin composition can be increased, so that the abrasion resistance can be improved. The content of the metal hydroxide may be 50 parts by mass or more, or 60 parts by mass or more. Further, the content of the metal hydroxide may be 120 parts by mass or less, 110 parts by mass or less, 100 parts by mass or less, 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, or 60 parts by mass or less.

[0037] The resin composition may not substantially contain a brominated flame retardant. A brominated flame retardant is an organic compound having at least one or more halogens, which can capture hydroxyl radicals and suppress the combustion of the resin composition. However, brominated flame retardants may be subject to future environmental regulations. If environmental regulations are enacted, the use of resin compositions containing brominated flame retardants may be restricted. Since the resin composition according to this embodiment contains a metal hydroxide, the resin composition has flame retardancy even if it does not substantially contain a brominated flame retardant. Note that the resin composition not substantially containing a brominated flame retardant means that the resin composition contains 1 part by mass or less of a brominated flame retardant with respect to 100 parts by mass of polyolefin. Note that the resin composition may contain 0.5 part by mass or less, or 0.1 part by mass or less of a brominated flame retardant with respect to 100 parts by mass of polyolefin.

[0038] In the resin composition of this embodiment, various additives can be appropriately blended within a range that does not interfere with the effects of this embodiment. Examples of the additives include crosslinking aids, flame retardant aids, metal deactivators, copper corrosion inhibitors, antioxidants, lubricants, fillers, reinforcing agents, ultraviolet absorbers, stabilizers, plasticizers, pigments, dyes, colorants, antistatic agents, foaming agents, and the like. The content of these additives is not particularly limited and can be appropriately determined according to the purpose.

[0039] The Shore D hardness of the resin composition may be less than 45. By setting the Shore D hardness of the resin composition to less than 45, the abrasion resistance of the resin composition can be improved. Note that the Shore D hardness of the resin composition is 0 or more, and may be 10 or more. The Shore D hardness of the resin composition can be measured according to JIS K7215:1986.

[0040] As described above, the resin composition according to this embodiment contains a polyolefin, a zeolite, an antioxidant, and a metal hydroxide. The resin composition contains 0.1 part by mass or more and 3.5 parts by mass or less of zeolite with respect to 100 parts by mass of the polyolefin. The resin composition contains 1 part by mass or more and 6.5 parts by mass or less of the antioxidant with respect to 100 parts by mass of the polyolefin. The mass ratio of the zeolite to the antioxidant is 0.08 or more and 3 or less.

[0041] Therefore, the resin composition according to this embodiment is excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using a brominated flame retardant that raises concerns about environmental regulations.

[0042] Since the resin composition according to this embodiment has the blending ratios of the zeolite and the antioxidant within a predetermined range, the time consumed by the antioxidant during heat treatment can be extended, and as a result, it is considered to have excellent heat resistance. In addition, since the resin composition according to this embodiment has the blending ratios of the zeolite and the antioxidant within a predetermined range, the addition amounts of the zeolite and the antioxidant can be kept low.

[0043] According to the resin composition according to this embodiment, it can also be used for a Flexible conductor and a thin-wall specification conforming to ISO19642, and it is also conceivable to achieve cost reduction by filling a large amount of filler.

[0044] [Coated electric wire] Next, the coated electric wire 1 according to this embodiment will be described with reference to FIG. 1. As shown in FIG. 1, the coated electric wire 1 according to this embodiment includes a conductor 2 and a coating layer 3 that coats the conductor 2 and is formed of the above resin composition. As described above, the resin composition according to the above embodiment is excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using a brominated flame retardant that raises concerns about environmental regulations. Therefore, the coated electric wire 1 can be preferably used, for example, as a coated electric wire 1 for automobiles.

[0045] The conductor 2 may be composed of only one strand wire, or may be formed by bundling a plurality of strand wires. The diameter of the conductor 2 and the diameter of the strand wire are not particularly limited and can be appropriately determined according to the application. The conductor 2 may be copper, aluminum, or an alloy containing these metals.

[0046] The resin composition for forming the coating layer 3 is produced by melt-kneading the above-described resin composition, and known means can be used for the method. For example, after pre-blending using a high-speed mixing device such as a Henschel mixer in advance, the resin composition can be obtained by kneading using a known kneader such as a Banbury mixer, a kneader, or a roll mill.

[0047] Known means can also be used for the method of coating the conductor 2 with the coating layer 3. For example, the coating layer 3 may be formed by a general extrusion molding method. The extruder used in the extrusion molding method may include, for example, a single-screw extruder or a twin-screw extruder. By extruding the molten resin and coating the outer periphery of the conductor 2 with the molten resin composition, the coating layer 3 that coats the outer periphery of the conductor 2 can be formed.

[0048] Thus, in the coated electric wire 1 of the present embodiment, the coating layer 3 can be formed by extrusion molding in the same manner as a general resin composition for electric wires. In addition, in order to improve the strength of the coating layer 3, after forming the coating layer 3 on the outer periphery of the conductor 2, the resin composition may be irradiated with radiation to crosslink the resin composition. As a result, the strength of the coating layer 3 can be improved.

[0049] As the radiation, for example, γ-rays or electron beams can be used as the radiation source. By irradiating the resin composition on the coating layer 3, radicals are generated in the molecule, and these radicals couple with each other to form intermolecular crosslinking bonds. As a result, it becomes possible to improve the strength of the coating layer 3. In addition, a crosslinking agent activated by radiation may be further blended in the coating layer 3 to further improve the strength of the coating layer 3.

[0050] Regarding the processing method of the resin composition, the kneading method of the resin composition, the coating method on the conductor 2, and the crosslinking method of the resin composition can be selected according to the purpose, and are not particularly limited.

[0051] As described above, the coated wire 1 according to the present embodiment includes a conductor 2 and a coating layer 3 that coats the conductor 2 and is formed of the above-described resin composition. The resin composition is excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using a brominated flame retardant that raises environmental regulatory concerns. Therefore, the coated wire 1 can be preferably used, for example, as a coated wire 1 for automobiles. Further, since the resin composition contains polyolefin, a coated wire 1 that is less expensive than a silicone rubber wire can be provided.

[0052] [Wire harness] Next, the wire harness according to the present embodiment will be described. The wire harness according to the present embodiment includes the above-described coated wire 1. The coating layer 3 of the coated wire 1 is formed of a resin composition, and the resin composition is excellent in flame retardancy and heat resistance and can suppress moisture absorption and bleeding without using a brominated flame retardant that raises environmental regulatory concerns. Therefore, the wire harness according to the present embodiment can be preferably used, for example, as a wire harness routed in a vehicle such as an electric vehicle.

Examples

[0053] Hereinafter, the resin composition according to the present embodiment will be described in more detail with reference to Examples and Comparative Examples, but the resin composition according to the present embodiment is not limited to these Examples.

[0054] The following materials were melt-kneaded in the compounding amounts (parts by mass) shown in the table using a resin mixer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) to prepare resin compositions for each example. The resin compositions were crosslinked under the conditions of 750 kV × 160 kGy.

[0055] [Polyolefin] ENGAGE (Registered Trademark) 7256 (manufactured by Dow), ethylene-butene copolymer, polyolefin elastomer

[0056] [Zeolite] (1) Type A zeolite, pore diameter 3 Å, SiO2 / Al2O3 = 2, cation species K + , Zeolam (Registered Trademark) A-3 (product model number) (manufactured by Tosoh Corporation) (2) Type A zeolite, pore diameter 4 Å, SiO2 / Al2O3 = 2, cation species Na + , Zeolam (Registered Trademark) A-4 (product model number) (manufactured by Tosoh Corporation) (3) Type A zeolite, pore diameter 5 Å, SiO2 / Al2O3 = 2, cation species Ca 2+ , Zeolam (Registered Trademark) A-5 (product model number) (manufactured by Tosoh Corporation) (4) ZSM-5 type zeolite, pore diameter 5.8 Å, SiO2 / Al2O3 = 40, cation species H + , HSZ (Registered Trademark) 840HOA (product model number) (manufactured by Tosoh Corporation) (5) ZSM-5 type zeolite, pore diameter 5.8 Å, SiO2 / Al2O3 = 1500, cation species H + , HSZ (Registered Trademark) 891HOA (product model number) (manufactured by Tosoh Corporation) (6) Beta type zeolite, pore diameter 6.5 Å, SiO2 / Al2O3 = 40, cation species H + , HSZ (Registered Trademark) 940HOA (product model number) (manufactured by Tosoh Corporation) (7) Y type zeolite, pore diameter 9.0 Å, SiO2 / Al2O3 = 5.5, cation species H + , HSZ (Registered Trademark) 320HOA (product model number) (manufactured by Tosoh Corporation) (8) Y type zeolite, pore diameter 9.0 Å, SiO2 / Al2O3 = 100, cation species H + , HSZ (Registered Trademark) 385HUA (product model number) (manufactured by Tosoh Corporation)

[0057] [Antioxidant] Irganox® 1010 (manufactured by BASF), pentaerythritol tetrakis[3-(3,5-di(tert-butyl)-4-hydroxyphenyl)propionate]

[0058] [Metal hydroxide] Magnesium hydroxide KISUMA® 5A (manufactured by Kyowa Chemical Industry Co., Ltd.) surface-treated with a higher fatty acid

[0059] [Evaluation] The flame retardancy, heat resistance, moisture absorption, bleedability, and hardness of the resin composition prepared as described above were evaluated as follows.

[0060] (Flame retardancy) In accordance with JIS K7201-2, the oxygen index of a 3 mm thick resin composition subjected to crosslinking treatment was measured for flame retardancy evaluation. When the oxygen index was 21.0 or higher, it was rated as "〇", and when it was less than 21.0, it was rated as "×".

[0061] (Heat resistance) After molding the crosslinked resin composition into a 1 mm thick resin sheet, it was punched out in the shape of dumbbell No. 3 specified in JIS K6251:2010. The punched dumbbell-shaped sheet was heated at 170 °C for 150 hours in accordance with JIS K7212:1999. The heated sheet was taken out of the oven and left at room temperature (about 23 °C) for 12 hours. Then, using the sheet cooled to room temperature as a test sample, a tensile test was carried out at a tensile speed of 200 mm / min at room temperature (23 °C). When the elongation rate of the test sample was 100% or more, the heat resistance was evaluated as "〇", and when the elongation rate of the test sample was less than 100%, it was evaluated as "×".

[0062] (Moisture absorption) Pellets were produced from the crosslinked resin composition, and the pellets were vacuum degassed at 40 °C using a vacuum dryer, and then left standing for 168 hours at room temperature (23 °C) and a humidity of 40% to 60%. The moisture content of this test sample was measured by Method A (anhydrous methanol extraction method) specified in JIS K7251:2002. When the moisture content was less than 1,500 ppm, it was evaluated as "〇", and when the moisture content was 1,500 ppm or more, it was evaluated as "×" for hygroscopicity.

[0063] (Bleedability) The resin composition was molded into a resin sheet with a thickness of 0.5 mm and a width of 50 mm, and cut into 200 mm lengths. This resin sheet was subjected to a crosslinking treatment, and the bleed on the resin sheet was wiped off using acetone. Then, it was left standing for 1,000 hours at room temperature (23 °C) and a humidity of 40% to 60%. Then, the bleed on the resin sheet was wiped off again using acetone. And the weight difference between the sample weight before the first wiping and the sample weight after the second wiping was determined as the bleed amount of the bleed that bled out on the resin sheet surface. The bleed amount was converted to the mass per unit area from the length and width of the resin sheet. When the bleed amount was less than 0.150 mg / cm 2 it was evaluated as "〇", and when the bleed amount was 0.150 mg / cm 2 or more, it was evaluated as "×" for bleedability.

[0064] (Hardness) After the crosslinked resin composition was molded into a resin sheet with a thickness of 2 mm, test samples were prepared by punching out to the sizes specified in JIS K7215:1986. And the punched test samples were stacked with three or more so that the thickness became 6 mm or more. The shore D hardness of this sample was measured using a type D durometer. When the shore D hardness was less than 45, it was evaluated as "〇", and when the shore D hardness was 45 or more, it was evaluated as "×" for hardness.

[0065]

Table 1

[0066]

Table 2

[0067]

Table 3

[0068] As shown in Table 1 and Table 2, the resin compositions according to Examples 1 to 19 were excellent in flame retardancy, heat resistance, hygroscopicity, and bleedability. Further, since the resin compositions according to Examples 1 to 18 contained 130 parts by mass or less of the metal hydroxide, the hardness was higher than that of the resin composition according to Example 19 containing 140 parts by mass of the metal hydroxide.

[0069] On the other hand, as shown in Table 3, sufficient heat resistance could not be obtained in the resin composition according to Comparative Example 1 that did not contain zeolite. Further, in the resin composition according to Comparative Example 2, since it contained 4 parts by mass of zeolite and the mass ratio of zeolite to the antioxidant was 4, the evaluation of hygroscopicity became "×". Further, in the resin composition according to Comparative Example 3, since the mass ratio of zeolite to the antioxidant was 0.07, the evaluation of bleedability became "×". Further, in the resin composition according to Comparative Example 4, similar to Comparative Example 2, since it contained 4 parts by mass of zeolite and the mass ratio of zeolite to the antioxidant was 4, the evaluation of hygroscopicity became "×". Further, in the resin composition according to Comparative Example 5, since magnesium hydroxide was not added, the evaluation of flame retardancy became "×".

[0070] As described above, although the present embodiment has been described, the present embodiment is not limited thereto, and various modifications are possible within the scope of the gist of the present embodiment.

Explanation of Signs

[0071] 1 Coated electric wire 2 Conductor 3 Coating layer

Claims

1. a polyolefin, a zeolite, an antioxidant, a metal hydroxide, a resin composition comprising: the resin composition contains 0.1 part by mass or more and 3.5 parts by mass or less of the zeolite with respect to 100 parts by mass of the polyolefin, the resin composition contains 1 part by mass or more and 6.5 parts by mass or less of the antioxidant with respect to 100 parts by mass of the polyolefin, a resin composition, wherein a mass ratio of the zeolite to the antioxidant is 0.08 or more and 3 or less.

2. The resin composition according to claim 1, wherein a pore diameter of the zeolite is 6.5 Å or less.

3. The resin composition according to claim 1, wherein the pore diameter of the zeolite is 6.6 Å or more and 9.0 Å or less, and a molar ratio of silica to alumina in the zeolite is 10 or less.

4. the polyolefin is crosslinked, The resin composition according to claim 1 or 2, wherein the polyolefin contains at least one of polyethylene and an ethylene copolymer.

5. the metal hydroxide contains magnesium hydroxide, The resin composition according to claim 1 or 2, wherein the resin composition contains 40 parts by mass or more and 130 parts by mass or less of the metal hydroxide with respect to 100 parts by mass of the polyolefin.

6. The resin composition according to claim 1 or 2, wherein a Shore D hardness of the resin composition is less than 45.

7. The resin composition according to claim 1 or 2, wherein the resin composition substantially does not contain a brominated flame retardant.

8. a conductor, a coating layer covering the conductor and formed of the resin composition according to claim 1 or 2, a coated electric wire comprising the same.

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