WO2013108329A1 - Flame-retardant electric wire/cable - Google Patents

Description

Flame retardant wire / cable

The embodiment of the present invention relates to an electric wire / cable that is halogen-free and excellent in flame retardancy and mechanical properties.

In recent years, in the field of electric wires and cables, in consideration of the environment, instead of a composition containing polyvinyl chloride (PVC) that generates harmful gases such as hydrogen halide during incineration or a halogen-based flame retardant, polyolefin has been used. 2. Description of the Related Art Electric wires and cables using a halogen-free composition made flame-retardant by adding a metal hydroxide such as aluminum hydroxide or magnesium hydroxide as a material for an insulator or a sheath have been widely used.

However, in such a halogen-free flame retardant composition, it is difficult to achieve both flame retardancy and mechanical properties (tensile strength, elongation, etc.), and a large amount of metal hydroxide is added to increase flame retardancy. However, if the amount of the metal hydroxide is decreased in order to obtain good mechanical properties, the flame retardancy becomes insufficient.

Therefore, various technologies have been proposed to solve such problems. For example, Patent Document 1 discloses an automotive electric wire in which a composition obtained by combining two specific types of polyolefin, two specific types of inorganic flame retardants such as huntite and hydromagnesite, is disclosed. Patent Document 2 discloses an electric wire / cable coated with a composition in which an olefin polymer is mixed with a metal oxide instead of a metal hydroxide and a specific metal salt that releases an incombustible gas during combustion. It is disclosed.

However, although some improvement is recognized in such a conventional technique, the effect is not sufficient, and an electric wire / cable having both sufficient flame retardancy and mechanical characteristics has not yet been obtained.

Japanese Patent Laid-Open No. 6-200089 JP 2010-1111760 A

An embodiment of the present invention aims to provide a wire / cable that is halogen-free and has both excellent flame retardancy and mechanical properties.

As a result of intensive research to achieve the above-mentioned object, the present inventors have found that a specific antioxidant and anti-aging agent, a specific cross-linking agent and a cross-linking aid are added to two specific ethylene copolymers. It has been found that a halogen-free flame-retardant resin composition that is remarkably excellent in flame retardancy can be obtained without adding a large amount of flame retardant by adding in combination with an agent.

The flame-retardant electric wire / cable of the embodiment of the present invention includes a coating made of a crosslinked body of a halogen-free flame-retardant resin composition on the outer periphery of the conductor. Halogen-free flame-retardant resin composition comprises an antioxidant for 100 parts by mass of polyolefin comprising 60 to 90% by mass of ethylene / propylene / diene copolymer and 10 to 40% by mass of ethylene / α-olefin copolymer. 0.1 to 5.0 parts by mass of bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide and 0.1 to 5.0 parts by mass of tetrakis- [Methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] containing methane and 0.1 to 5.0 parts by mass of 2-mercaptobenzimidazole as an antioxidant 1.0 to 4.0 parts by weight of dicumyl peroxide as a crosslinking agent, and 0.5 to 6.0 parts by weight of ethylene glycol as a crosslinking aid. Including a call dimethacrylate.

According to the embodiment of the present invention, a flame-retardant electric wire / cable that is halogen-free and has both excellent flame retardancy and excellent mechanical properties is provided.

It is a cross-sectional view which shows the flame-retardant electric wire and cable of one Embodiment. It is a cross-sectional view which shows the flame-retardant electric wire and cable of other embodiment.

Hereinafter, embodiments of the present invention will be described.

The halogen-free flame-retardant resin composition used for the flame-retardant electric wire / cable of the present invention will be described.

The halogen-free flame retardant resin composition contains polyolefin as a base polymer and contains a non-halogen flame retardant, as well as an antioxidant, an antioxidant, a crosslinking agent, and a crosslinking aid.

The base polymer polyolefin is a combination of an ethylene / propylene / diene copolymer (EPDM) and an ethylene / α-olefin copolymer. The ethylene / propylene / diene copolymer is obtained by copolymerizing ethylene and propylene with a non-conjugated polyene. Examples of the non-conjugated polyene include dicyclopentadiene, 1,4-hexadiene, ethylidene norbornene, and vinyl norbornene. The ethylene / α-olefin copolymers are propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1- Copolymerized with one or more α-olefins such as tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 4-methyl-1-pentene and the like It is. Any of these may be used alone or in combination of two or more.

For the purpose of the present invention, the ethylene / propylene / diene copolymer is ethylidene norbornene (ENB) as the third component, the Mooney viscosity ML _{1 + 4} (125 ° C.) is 30 or less, and the ethylene content is 60 It is preferable to use a material having a mass% or more. Specific examples of suitable commercially available ethylene / propylene / diene copolymers include, for example, JSR EP51 (trade name, manufactured by JSR Corporation; Mooney viscosity ML _{1 + 4} (125 ° C.) 23, ethylene content 67% by mass, diene And a diene component ENB).

Further, the ethylene / α-olefin copolymer has a density of 850 to 950 kg / m ³ and a melt flow rate (MFR: 190 ° C., load 2.16 kg) specified in JIS K 7210 of 1.0 to 1. It is preferable to use one that is 6 g / 10 min. Specific examples of suitable commercially available ethylene / α-olefin copolymers include Tafmer A1085, Tafmer A1085S (trade names manufactured by Mitsui Chemicals, Inc.), and the like. Tuffmer A1085 has a density of 880 kg / m ³ , MFR (190 ° C., load 2.16 kg) is 1.4 g / 10 min, Tuffmer A 1085S has a density of 885 kg / m ³ , MFR (190 ° C., load 2.16 kg) Is 1.2 g / 10 min.

In one embodiment, the blend composition of the two components in the base polymer is 60 to 90% by mass of an ethylene / propylene / diene copolymer and 10 to 40% by mass of an ethylene / α-olefin copolymer. By setting it as such a compounding composition, it can be set as the flame-retardant polyolefin composition which has favorable softness | flexibility and mechanical strength, having a halogen-free flame retardance. That is, when the blending amount of the ethylene / propylene / diene copolymer is less than 60% by mass, flexibility and mechanical properties are deteriorated. On the other hand, if the blending amount of the ethylene / propylene / diene copolymer exceeds 90% by mass, the flame retardancy decreases. The blending composition of both components in the base polymer is preferably 70 to 80% by mass of ethylene / propylene / diene copolymer and 20 to 30% by mass of ethylene / α-olefin copolymer.

Non-halogen flame retardants used in the halogen-free flame retardant resin composition of the present invention include metal hydroxides such as magnesium hydroxide, aluminum hydroxide and calcium hydroxide, nitrogen such as guanidine and melamine. And phosphoric flame retardants such as ammonium phosphate and red phosphorus, phosphorus-nitrogen flame retardants, boric acid compounds such as zinc borate, and calcium carbonate. These may be used individually by 1 type, and may mix and use 2 or more types.

Among the non-halogen flame retardants, metal hydroxides are preferable, magnesium hydroxide or a combination of magnesium hydroxide and other metal hydroxides is more preferable, and the use of magnesium hydroxide alone is even more preferable. When the hydroxide is used alone, the blending amount is preferably in the range of 50 to 250 parts by mass with respect to 100 parts by mass of the polyolefin of the base polymer. In the present invention, by using a specific antioxidant, an anti-aging agent, a crosslinking agent, and a crosslinking aid described later, high flame retardancy can be obtained even if the amount of the flame retardant is reduced.

The halogen-free flame retardant resin composition used in the present invention contains, as an antioxidant, bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide, and Tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane is used in combination. Further, 2-mercaptobenzimidazole is used as an anti-aging agent. Further, dicumyl peroxide (DCP) and ethylene glycol dimethacrylate (EDMA) are used as a crosslinking agent and a crosslinking aid, respectively.

Of the two compounds used as antioxidants, one bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide is used as a thioether antioxidant. As a known product, for example, ADK STAB AO-23 (trade name) manufactured by ADEKA can be cited. This bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide is blended in an amount of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polyolefin of the base polymer. The When the blending amount is less than 0.1 parts by mass, the effect of addition is small and the flame retardancy cannot be improved. Moreover, when a compounding quantity exceeds 5.0 mass parts, there is a possibility that an effect will not change so much and it may bloom on the surface, when coat | covering a conductor outer periphery. This component is preferably blended in an amount of 1.0 to 4.0 parts by weight, more preferably 2.5 to 3.5 parts by weight, based on 100 parts by weight of the polyolefin.

The other tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane used as an antioxidant is known as a hindered phenolic antioxidant. As a commercially available product, for example, ADEKA STAB AO-60 (trade name) manufactured by ADEKA can be used. The tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polyolefin of the base polymer. Partly formulated. When the blending amount is less than 0.1 parts by mass, the effect of addition is small and the flame retardancy cannot be improved. Moreover, when a compounding quantity exceeds 5.0 mass parts, there is a possibility that an effect will not change so much and it may bloom on the surface, when coat | covering a conductor outer periphery. This compound is preferably blended in an amount of 0.3 to 2.0 parts by weight, more preferably 0.5 to 1.5 parts by weight, based on 100 parts by weight of the polyolefin.

2-Mercaptobenzimidazole used as an anti-aging agent is known as a benzimidazole-based anti-aging agent. Is mentioned. The 2-mercaptobenzimidazole is blended in an amount of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the base polymer polyolefin. When the blending amount is less than 0.1 parts by mass, the effect of addition is small and the flame retardancy cannot be improved. Moreover, when a compounding quantity exceeds 5.0 mass parts, there is a possibility that an effect will not change so much and it may bloom on the surface, when coat | covering a conductor outer periphery. This compound is preferably blended in an amount of 0.5 to 3.0 parts by weight, more preferably 1.5 to 2.5 parts by weight, based on 100 parts by weight of the polyolefin.

Dicumyl peroxide (DCP) and ethylene glycol dimethacrylate (EDMA), which are used as a crosslinking agent and a crosslinking aid, are generally known as organic peroxide crosslinking agents and crosslinking aids, respectively. In the present invention, it is necessary to use these two kinds of organic peroxide crosslinking agents and their crosslinking aids, and it is necessary to use other crosslinking agents and crosslinking aids. The effect of the present invention cannot be obtained.

In addition, these blending amounts are 1.0 to 4.0 parts by mass for dicumyl peroxide and 0.5 to 6.0 parts by mass for ethylene glycol dimethacrylate with respect to 100 parts by mass of the polyolefin of the base polymer. . If any of dicumyl peroxide and ethylene glycol dimethacrylate is less than the above range, crosslinking is not sufficiently performed and flame retardancy is also lowered. Moreover, when a compounding quantity exceeds the said range, mechanical characteristics will fall and heat aging characteristics will also fall. Dicumyl peroxide is preferably blended in an amount of 2.0 to 4.0 parts by weight, more preferably 2.5 to 3.5 parts by weight, based on 100 parts by weight of polyolefin. Ethylene glycol dimethacrylate is preferably blended in an amount of 2.0 to 5.0 parts by weight, more preferably 3.5 to 4.5 parts by weight, based on 100 parts by weight of polyolefin.

1.0 to 4.0 parts by mass of bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide, 100% by mass of tetrakis- [ Methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane in an amount of 0.3 to 2.0 parts by mass, and 2-mercaptobenzimidazole in an amount of 0.5 to 3.0. It is preferable to blend 2.0 parts by mass with 2.0 parts by mass of dicumyl peroxide and 2.0 to 5.0 parts by mass of ethylene glycol dimethacrylate. 2.5 to 3.5 parts by mass of bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide with respect to 100 parts by mass of the polyolefin of the base polymer, tetrakis- [ Methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane in an amount of 0.5 to 1.5 parts by mass, 2-mercaptobenzimidazole in an amount of 1.5 to 2.5 More preferably, 2.5 parts by weight of dicumyl peroxide and 3.5 parts by weight of ethylene glycol dimethacrylate are blended.

In the halogen-free flame-retardant resin composition used in the present invention, an ultraviolet absorber, a filler, and a processing aid that are generally blended in this type of resin composition within a range that does not impair the effects of the present invention. Additives such as lubricants and colorants can be blended.

Examples of the ultraviolet absorber include 2- (2′-hydroxy-4′-n-octoxyphenyl) benzotriazole, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4. -Hydroxybenzoate and the like.

Examples of the filler include fused silica, crystalline silica, alumina, zirconia, talc, clay, mica, calcium carbonate, titanium white, bengara, silicon carbide, boron nitride, silicon nitride, and aluminum nitride.

Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, and salts or esters thereof.

Examples of the lubricant include hydrocarbons, fatty acids, fatty acid amides, esters, and alcohols.

Each of the above additives may be used alone or in combination of two or more.

The halogen-free flame retardant resin composition used in the present invention comprises the above-described polyolefin, antioxidant, anti-aging agent, crosslinking agent, and crosslinking aid, and various components described above that are blended as necessary. It can be easily prepared by uniformly mixing using a conventional kneader such as a Banbury mixer, a tumbler, a pressure kneader, a kneading extruder, or a mixing roller.

The flame-retardant electric wire / cable of the present invention can be produced by extrusion-coating the halogen-free flame-retardant resin composition on a conductor directly or through another coating, followed by heat crosslinking. The material and outer diameter of the conductor, the presence or absence of twisting, and the like are not particularly limited, and are appropriately selected depending on the application. The temperature condition for crosslinking the halogen-free flame retardant resin composition is usually 170 to 250 ° C., preferably 180 to 220 ° C.

FIG. 1 is a cross-sectional view showing a flame-retardant electric wire / cable according to an embodiment of the present invention.

As shown in FIG. 1, the flame-retardant electric wire / cable 10 of this embodiment has a conductor 11 made of one or more tin-plated annealed copper wires or the like. On this conductor 11, an insulator 12 made of cross-linked polyethylene is provided by a conventional method. Further, a sheath 13 is formed on the insulator 12 by extrusion-coating the halogen-free flame retardant resin composition described above, followed by heat crosslinking.

It is preferable that the flame-retardant electric wire / cable 10 of this embodiment is comprised so that the following requirements may be satisfied.
(1) The tensile strength and elongation (measured according to JIS K 6253) of the sheath 13 are 7 MPa or more and 300% or more, respectively.
(2) The oxygen index of the sheath 13 (measured according to JIS K 7201-2) is 30 or more.
(3) The volume resistivity (measured according to JIS K 6723) of the sheath 13 is 1 × 10 ¹⁵ Ω · cm or more.

In the flame-retardant electric wire / cable 10 of the present embodiment, a specific ratio of a specific antioxidant and an anti-aging agent, a specific cross-linking agent and a cross-linking aid to the specific two kinds of ethylene-based copolymers. A coating made of a cross-linked halogen-free flame retardant resin blended in (1) is provided. This coating can have good flame retardancy despite a small amount of flame retardant used compared to a coating made of a composition using a conventional halogen-free flame retardant resin composition. For this reason, it can have the flame-retardant property and mechanical characteristics which were excellent in halogen-free.

FIG. 2 is a cross-sectional view showing a flame-retardant electric wire / cable according to another embodiment of the present invention.

In the flame-retardant electric wire / cable 20 of the present embodiment, three insulation core wires 21 covered with an insulator 12 made of crosslinked polyethylene are twisted together with an interposition 14 on a conductor 11, and a press-wound tape 15 is wound around the outer periphery thereof. The sheath 13 is covered therewith. And the sheath 13 is formed by heat-crosslinking, after extrusion-coating the halogen-free flame-retardant resin composition mentioned above.

Since the flame-retardant electric wire / cable 20 of the present embodiment also includes the sheath 13 made of the halogen-free flame-retardant resin composition described above, similarly to the flame-retardant electric wire / cable 10 of the first embodiment, it is halogen-free. It has both excellent flame retardancy and mechanical properties.

It is preferable that the flame-retardant electric wire / cable 20 is also configured to satisfy the requirements (1) to (3).

Although several embodiments of the present invention have been described, the present invention is not limited to the description of the embodiments described above, and can be appropriately changed without departing from the gist of the present invention. Needless to say.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The components used in Examples and Comparative Examples are as follows.

EPDM (1):
Product name JS EP51 manufactured by JSR Corporation
(Ethylene content 67% by weight, Mooney viscosity ML _{1 + 4} 23)
EPDM (2):
Product name JS EP21 manufactured by JSR Corporation
(Ethylene content 61% by weight, Mooney viscosity ML _{1 + 4} 23)
Ethylene / α-olefin copolymer:
Product name TAFMER A1085S manufactured by Mitsui Chemicals, Inc.
Magnesium hydroxide:
Kyowa Chemical Industry Co., Ltd. Brand name Kisuma 5A
Antioxidant (1):
Bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5
tert-butylphenyl] sulfide;
ADEKA product name ADK STAB AO-23
Antioxidant (2):
Tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-
Hydroxyphenyl) propionate] methane;
ADEKA product name ADK STAB AO-60
Antioxidant (3):
Bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl)
Propionate];
Product name Irganox 1035 manufactured by BASF
Antioxidant (4):
Tetrakis [methylene-3- (dodecylthio) propionate] methane;
ADEKA product name ADK STAB AO-412S
Anti-aging agent:
2-mercaptobenzimidazole;
Product name NOCRACK MB made by Ouchi Shinsei Chemical Co., Ltd.

Example 1
EPDM (1) 70.0 parts by mass, ethylene / α-olefin copolymer 30.0 parts by mass, magnesium hydroxide 150.0 parts by mass, antioxidant (1) 0.2 parts by mass, antioxidant (2 ) 0.2 parts by weight, 0.2 parts by weight of anti-aging agent, 1.8 parts by weight of dicumyl peroxide (DCP), and 1.0 parts by weight of ethylene glycol dimethacrylate (EDMA) were uniformly kneaded with a mixing roll. A flame retardant resin composition was obtained.

Next, a 1.2 mm thick insulator made of cross-linked polyethylene is coated on a copper stranded wire conductor having a cross-sectional area of 38 mm ^{2 by} a conventional method, and then the above flame retardant resin composition is extrusion coated to a thickness of 1.5 mm thereon. Then, it was heated and crosslinked at 200 ° C. for 3 minutes to produce a flame-retardant wire / cable having an outer diameter of about 12.5 mm.

(Examples 2 to 10, Comparative Examples 1 to 8)
A flame retardant resin composition was prepared in the same manner as in Example 1 except that the composition of the flame retardant resin composition was changed as shown in Table 1. In addition, flame retardant using these compositions was prepared. Electric wires and cables were manufactured.

About the flame retardant resin composition obtained by each said Example and each comparative example, various characteristics were evaluated by the method shown below.
[Tensile strength and elongation]
Separately from the cable, a test sheet (1 mm thick) is press-molded from a flame retardant resin composition (heated and pressed at 170 ° C., 5 MPa for 20 minutes), and from this test sheet, a No. 3 dumbbell as defined in JIS K 6251 The test piece was punched out and subjected to a tensile test based on JIS C 3005 (mark interval 20 mm, tensile speed 200 mm / min), and the tensile strength and elongation at break were measured.
[Oxygen index]
In the same manner as described above, a test sheet (3 mm thick) made of a flame retardant resin composition is prepared separately from the cable, and a test piece having a width of 6.5 mm and a length of 150 mm is punched from the test sheet. Measured according to 7201-2.
[Volume resistivity]
In the same manner as described above, a test sheet (0.5 mm thickness) made of a flame retardant resin composition was prepared separately from the cable, and measured at room temperature using DC500V based on JIS K 6723.

These results are shown in Table 1.

As is clear from Table 1, in Examples 1 to 10, good results were obtained in tensile strength, elongation, oxygen index, and volume resistivity.

Further, the blending amount with respect to 100 parts by mass of the polyolefin is adjusted to an antioxidant (1) (bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide) 1.0 to 4 0.0 part by mass, antioxidant (2) (tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane) 0.3 to 2.0 parts by mass Parts, anti-aging agent (2-mercaptobenzimidazole) 0.5 to 3.0 parts by mass, DCP (dicumyl peroxide) 2.0 to 4.0 parts by mass, EDMA (ethylene glycol dimethacrylate) 2.0 to 5 By setting the content to 0.0 parts by mass, better results were obtained in tensile strength (Examples 3 to 8).

Further, the blending amount with respect to 100 parts by mass of the polyolefin is adjusted to the antioxidant (1) (bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide) 2.5-3. 0.5 parts by mass, antioxidant (2) (tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane) 0.5 to 1.5 parts by mass Parts, anti-aging agent (2-mercaptobenzimidazole) 1.5 to 2.5 parts by mass, DCP (dicumyl peroxide) 2.5 to 3.5 parts by mass, EDMA (ethylene glycol dimethacrylate) 3.5 to 4 When the content was .5 parts by mass, better results were obtained in the oxygen index (Examples 5 and 6).

10, 20 ... Flame-retardant electric wire / cable, 11 ... Conductor, 12 ... Insulator, 13 ... Sheath, 14 ... Intervening, 15 ... Pressing tape, 21 ... Insulating core.

Claims (7)

Including a conductor and a coating made of a crosslinked product of a halogen-free flame-retardant resin composition provided on the outer periphery of the conductor;
The halogen-free flame retardant resin composition comprises an antioxidant for 100 parts by mass of a polyolefin comprising 60 to 90% by mass of an ethylene / propylene / diene copolymer and 10 to 40% by mass of an ethylene / α-olefin copolymer. 0.1 to 5.0 parts by mass of bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide and 0.1 to 5.0 parts by mass of tetrakis- [Methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] containing methane and 0.1 to 5.0 parts by mass of 2-mercaptobenzimidazole as an antioxidant Containing 1.0 to 4.0 parts by weight of dicumyl peroxide as a crosslinking agent and 0.5 to 6.0 parts by weight of ethylene as a crosslinking aid Flame-retardant wire or cable comprising a recall dimethacrylate. The halogen-free flame-retardant resin composition contains 1.0 to 4 bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide with respect to 100 parts by mass of polyolefin. 0.0 part by mass, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane 0.3-2.0 parts by mass, 2-mercaptobenzimidazole 2. The composition according to claim 1, comprising 0.5 to 3.0 parts by mass of dicumyl peroxide, 2.0 to 4.0 parts by mass of dicumyl peroxide, and 2.0 to 5.0 parts by mass of ethylene glycol dimethacrylate. Flame retardant wires and cables. The halogen-free flame-retardant resin composition contains 2.5 to 3 bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide with respect to 100 parts by mass of polyolefin. .5 parts by mass, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane 0.5 to 1.5 parts by mass, 2-mercaptobenzimidazole 2. The composition according to claim 1, comprising 1.5 to 2.5 parts by mass of dicumyl peroxide, 2.5 to 3.5 parts by mass of dicumyl peroxide, and 3.5 to 4.5 parts by mass of ethylene glycol dimethacrylate. Flame retardant wires and cables. The halogen-free flame retardant resin composition contains 50 to 250 parts by mass of a metal hydroxide as a flame retardant with respect to 100 parts by mass of polyolefin. Flame retardant wire / cable. The flame retardant electric wire / cable according to claim 4, wherein the metal hydroxide is magnesium hydroxide. The ethylene / propylene / diene copolymer has a Mooney viscosity ML _{1 + 4} (125 ° C.) of 30 or less and an ethylene content of 60% by mass or more. Flame retardant wire / cable as described in the section. The halogen-free flame-retardant resin composition has a tensile strength (JIS K 6253) of 7 MPa or more, an elongation (JIS K 6253) of 300% or more, an oxygen index (JIS K 7201-2) of 30 or more, and a volume. 7. The flame-retardant electric wire / cable according to claim 1, wherein the resistivity is 1 × 10 ¹⁵ Ω · cm or more.

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