JP2009286903A - Flame-retardant resin composition and electric wire coated therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant resin composition, which can be used for an electric wire coating material disposed to a section requiring heat resistance in an automobile and the like, achieves both of a heat resistance life and flame retardancy without using any PVC, causes no elution of heavy metal compounds, a great quantity of smoke, or generation of corrosive gas on disposal, and exhibits excellent compatibility with a PVC-containing member, and to provide an electric wire using the flame-retardant resin composition. <P>SOLUTION: The flame-retardant resin composition includes 100 pts.mass of an ethylene-vinyl acetate copolymer (a) wherein a vinyl acetate content is less than 40 mass% and more than 10 mass% or a mixture (b) of an ethylene-vinyl acetate copolymer and polyolefin, 50-160 pts.mass of a metal hydrate (c), 2-10 pts.mass of a phenolic antioxidant (d), 10-25 pts.mass of a benzimidazole antioxidant (e), and 0-10 pts.mass of a thioether antioxidant (f). The electric wire coated with the flame-retardant resin composition is also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an insulated wire used in automobiles and the like and a resin composition thereof, and more specifically, does not generate a large amount of smoke or harmful gas during combustion, flame retardancy, cold resistance, heat resistance, The present invention relates to a resin composition and an electric wire excellent in mechanical properties and moldability.

  Various properties such as flame retardancy and mechanical properties are required for members and electric wires used in automobiles, etc. The materials include polyvinyl chloride (PVC) compounds and bromine and chlorine atoms in the molecule. Polyolefin compounds containing halogen-based flame retardants containing benzene were mainly used.

In recent years, various problems have been pointed out when products using such materials are discarded without appropriate processing.
For example, when it is disposed of in landfill, there is a problem that a plasticizer and a heavy metal stabilizer mixed in the material are eluted, and when it is disposed of by incineration, a problem that a large amount of corrosive gas is generated occurs.

For this reason, non-halogen flame retardant materials that do not generate harmful heavy metals or corrosive halogen-based gases have been proposed, and some have been put into practical use. Non-halogen flame retardant materials that have been proposed and put to practical use are generally made of polyolefin-based resins highly filled with metal hydrates, but these materials are used to impart flame retardancy to the resins. It is necessary to add a large amount of metal hydrate, and as the base polymer, an ethylene-based copolymer that can easily be mixed with metal hydrate is mainly used.
However, it is known that the mechanical properties, heat resistance, etc. of such non-halogen flame retardant materials are low compared to the properties of currently used PVC compounds.

  In order to solve such problems, there are a method of crosslinking a halogen-free flame retardant material having an ethylene copolymer as a base polymer by chemical crosslinking or electron beam crosslinking, and a method of using polypropylene having excellent mechanical properties and heat resistance as a base polymer. It has been studied and put into practical use. However, when such non-halogen flame retardant materials are used as a coating material for electric wires used in automobiles, etc., especially for wires that require heat resistance, both heat resistance life and flame resistance are compatible. Is known to be difficult.

  In addition, as a problem of electric wires coated with non-halogen flame retardant materials, in the state of contact with a member formed of a material containing plasticizer or oil such as PVC tape, PVC electric wires, rubber products, etc. It has been found that the heat resistant life may be reduced.

For these problems, for example, in Patent Document 1, it is used for electric and electronic equipment having flame retardancy that passes the vertical flame test (Vertical Flame Test VW-1) defined in UL1581. An insulated wire is described. However, in this insulated wire, a large amount of metal hydrate is blended in order to obtain high flame retardancy, and depending on the application, tensile elongation may not be sufficient. It was sought after.
Further, Patent Document 2 describes a non-halogen electric wire that is coated with a coating material made of a polyolefin-based resin containing aluminum hydroxide as a flame retardant and has a small life reduction even when it comes into contact with a member containing a PVC resin. ing. However, in this electric wire, reduction of thermal deterioration caused by contact with a member containing PVC resin has not been sufficient.
JP 2000-129064 A JP 2006-179552 A

  Therefore, the present invention uses PVC to achieve both heat resistant life and flame retardancy, which can be used as a coating material for electric wires used in automobiles and the like, in particular, electric wires arranged in parts where heat resistance is required. A flame retardant resin composition that is free from elution of heavy metal compounds, generation of large amounts of smoke and corrosive gas, and excellent coexistence with PVC-containing members at the time of disposal such as landfill and incineration, And it aims at providing the electric wire using the same.

The above problem has been solved by the following means. That is, the present invention
(1) The vinyl acetate content is 10% by weight or more and less than 40% by weight, based on 100 parts by weight of (a) an ethylene / vinyl acetate copolymer or (b) a mixture of an ethylene / vinyl acetate copolymer and a polyolefin. (C) 50 to 160 parts by mass of metal hydrate, (d) 2 to 10 parts by mass of phenolic antioxidant, (e) 10 to 25 parts by mass of benzimidazole antioxidant, (f) thioether oxidation A flame retardant resin composition comprising 0 to 10 parts by mass of an inhibitor;
(2) The flame retardant resin composition according to (1), wherein the (c) metal hydrate is surface-treated with a silane coupling agent,
(3) The flame retardant according to (1) or (2), wherein the metal hydrate (c) is aluminum hydroxide, magnesium hydroxide, or a mixture of aluminum hydroxide and magnesium hydroxide. Resin composition, and
(4) An electric wire characterized by covering a conductor with the flame retardant resin composition described in any one of (1) to (3) and performing a crosslinking treatment.

  The flame-retardant resin composition of the present invention and the electric wire coated therewith are heat resistant, flame-retardant, coexistence with other members, particularly PVC (for example, prevention of thermal degradation under contact with PVC), terminal processing In addition, there is no problem of elution of heavy metal compounds, generation of large amounts of smoke, and corrosive gas at the time of disposal such as landfill and incineration.

  Hereinafter, each component contained in the flame retardant resin composition used to coat the conductor and form an insulator in the present invention will be described.

(A) ethylene / vinyl acetate copolymer or (b) mixture of ethylene / vinyl acetate copolymer and polyolefin In the present invention, (a) ethylene / vinyl acetate copolymer or (b) ethylene / vinyl acetate copolymer The mixture of the coalescence and the polyolefin needs to have a vinyl acetate content as a constituent component of 10% by mass or more and less than 40% by mass.
When the vinyl acetate content is less than 10% by mass, there is a possibility that the combustion test specified by JIS C3005 or JASO D608, which is a standard for electric wires, may be rejected.
On the other hand, when the vinyl acetate content is 40% by mass or more, mechanical properties such as tensile strength and abrasion resistance specified by the above standards may be insufficient.
In the present invention, it is possible to make the vinyl acetate content of the mixture less than 40% by mass by mixing an ethylene / vinyl acetate copolymer having a high vinyl acetate content and a polyolefin.

The composition mixed with the polyolefin is highly effective in preventing the pellets of the composition from blocking in the hopper of the extruder, which is a molding apparatus, or in the screw supply section when the conductor is coated and an insulator is formed.
In addition, the effect of alleviating and preventing the insulating coating layer from being crushed or damaged by the transmission line and the winding line after the conductor is coated with the composition is also high.

  Examples of the polyolefin to be mixed include, for example, very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene single weight Polymer (H-PP), ethylene-propylene block copolymer (B-PP), ethylene-propylene random copolymer (R-PP), and those modified with unsaturated carboxylic acid or derivatives thereof It is done.

Examples of the unsaturated carboxylic acid include maleic acid, itaconic acid, and fumaric acid. Examples of the unsaturated carboxylic acid derivative include maleic acid monoester, maleic acid diester, maleic anhydride, itaconic acid monoester, and itaconic acid. Examples include diester, itaconic anhydride, fumaric acid monoester, fumaric acid diester, fumaric anhydride and the like.
The modification of polyolefin can be performed by, for example, melting and kneading polyolefin and unsaturated carboxylic acid in the presence of peroxide.
In the present invention, the polyolefin to be mixed is preferably a modified polyolefin and / or a mixture of a modified polyolefin and a polyolefin from the viewpoint of compatibility with the ethylene / vinyl acetate copolymer.

The melt flow rate (MFR) of ethylene / vinyl acetate copolymer or polyolefin is 0.1 to 10 g / 10 min (ethylene / vinyl acetate copolymer, ultra-low density polyethylene, linear low density polyethylene, low density polyethylene). , Medium density polyethylene, high density polyethylene: load 2.16 kg, temperature 190 ° C., polypropylene homopolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer: load 2.16 kg, temperature 230 ° C.) .
When an ethylene / vinyl acetate copolymer or polyolefin having a melt flow rate of less than 0.1 g / 10 min is used, the load on the kneading equipment or extruder, which is a molding device for the composition or insulated wire, may increase. .
On the other hand, when an ethylene / vinyl acetate copolymer or polyolefin having a melt flow rate of 10 g / 10 min or more is used, the load on the extruder, which is a device for forming an insulated wire, is reduced. Between resin components (ethylene / vinyl acetate copolymer and polyolefin), resin components (ethylene / vinyl acetate copolymer, ethylene vinyl acetate copolymer and polyolefin) and other components (metal hydration) described below Product, phenolic antioxidant, benzimidazole antioxidant, thioether antioxidant) may be reduced.
The more preferable range of the melt flow rate is 0.5 to 5 g / 10 min (ethylene / vinyl acetate copolymer, ultra-low density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene: Load 2.16 kg, temperature 190 ° C., polypropylene homopolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer: load 2.16 kg, temperature 230 ° C.).

(C) Metal hydrate In the present invention, (c) metal hydrate used as a flame retardant includes aluminum hydroxide, magnesium hydroxide, hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydro Examples thereof include a compound having a hydroxyl group or crystal water such as talcite.
These metal hydrates can be used alone or in combination of two or more.
Moreover, in this invention, it becomes possible to obtain the insulated wire which has a favorable tensile characteristic by using the metal hydrate surface-treated with the silane coupling agent.
In addition, by using a phenolic antioxidant and a benzimidazole antioxidant together as an antioxidant, or further containing a thioether antioxidant, heat resistance using a metal hydrate without thermal degradation due to PVC contact It is possible to obtain an insulated wire having good flame retardancy.

As the silane coupling agent used for the surface treatment, a commonly used silane coupling agent can be used without particular limitation, but a silane cup having an organic functional group such as an amino group, a methacryl group, a vinyl group, an epoxy group, or a mercapto group. A ring agent is preferable, and a silane coupling agent having a vinyl group and / or an epoxy group is more preferable from the viewpoint of flame retardancy and tensile properties.
These include vinyl tris (β methoxyethoxy) silane, vinyl triethoxy silane, vinyl trimethoxy silane, γ- (methacryloyloxypropyl) trimethoxy silane, γ- (methacryloyloxypropyl) methyldimethoxysilane, β- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like.

As a metal hydrate surface-treated with a silane coupling agent, a metal hydrate surface-treated with a silane coupling agent in advance may be used, together with an untreated or surface-treated metal hydrate. A silane coupling agent may be blended and surface treatment may be performed.
The amount of the silane coupling agent at this time is appropriately added in an amount sufficient for the surface treatment, and specifically 0.1 to 2.0% by mass with respect to the metal hydrate is a preferable amount.

The compounding amount of the metal hydrate is (a) an ethylene / vinyl acetate copolymer or (b) an ethylene / vinyl acetate copolymer having a vinyl acetate content of 10% by mass or more and less than 40% by mass alone or in a mixture. It is 50-160 mass parts with respect to 100 mass parts of the mixture of polyolefin, Preferably, it is 70-120 mass parts.
If the blending amount of the metal hydrate is less than 50 parts by mass with respect to 100 parts by mass of (a) or (b), the combustion test specified by JIS C3005 or JASO D608, which is the standard for electric wires, will be rejected. there is a possibility.
On the other hand, when the compounding amount of the metal hydrate exceeds 160 parts by mass with respect to 100 parts by mass of (a) or (b), the tensile elongation specified by JASO D608 becomes insufficient, or the resin composition It may be hardened and the flexibility of the wire may be reduced.

As for the types of these metal hydrates, magnesium hydroxide is preferable from the viewpoint of heat resistance, and aluminum hydroxide is preferable from the viewpoint of coexistence with other members.
As such, for example, in the case of magnesium hydroxide, “Kisuma 5” “Kisuma 5A” “Kisuma 5B” “Kisuma 5J” “Kisuma 5L” “Kisuma 5P” (Kyowa Chemical Industry), “Magnifine H-7” “Magnifin H-10” (Albemarle Corporation), “Magsees N-1” “Magsees N-3” (Kamishima Chemical Industry), aluminum hydroxide, “Hijilite H42M”, “Hijilite H43M”, “Hijilite H42STV” (Showa Denko), “B1403”, “B1403T” (Nippon Light Metal), etc.

(D) phenolic antioxidants, (e) benzimidazole antioxidants, (f) thioether antioxidants Electric wires used in automobiles, etc., in particular, wires that are routed where heat resistance is required These coating materials are improved in heat resistance by crosslinking by an electron beam crosslinking method, a chemical crosslinking method or the like.
For automobiles, heat-resistant cross-linked PE electric wires described in JASO D608 (120 ° C. × 10,000 hours later, tensile elongation 100%), for electric / electronic devices, UL 125 ° C. heat-resistant electric wires (158 ° C. × 168 hours later, residual tensile strength 70 %, Over 150% tensile elongation residual), UL 150 ° C heat resistant wire (after 180 ° C x 168 hours, over 70% tensile strength residual, over 65% residual tensile elongation) and severe heat aging In order to pass the test standard, not only crosslinking but also high content of radical chain inhibitors such as amine antioxidants, phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants, etc. The method of improving the heat resistance is taken by the synergistic effect by using together the peroxide decomposition agent of this.

  However, although the above method is effective for a wire in which a cross-linked product of a composition in which a halogen-based flame retardant is blended with polyolefin is effective, a polyolefin resin (polyolefin, ethylene copolymer) highly filled with metal hydrate is effective. In the case of coalescence), the effect is reduced, and in particular, it will be required in the future due to the 120 ° C x 10000 hour heat-resistant life described in JASO D608, high voltage, high current, and high density of hybrid vehicles. It is difficult to provide an electric wire having a higher heat-resistant life (for example, 150 ° C. × 10000 hours).

  In the present invention, (d) phenolic antioxidant, (e) benzimidazole antioxidant, and (f) thioether antioxidant are used alone or in a mixture with a vinyl acetate content of 10% by mass or more and less than 40% by mass. High heat-resistant life of 120 ° C x 10000 hours, 150 ° C x 10,000 hours for a cross-linked product of an ethylene / vinyl acetate copolymer or a mixture of an ethylene / vinyl acetate copolymer and a polyolefin and a metal hydrate Formulated to give. In particular, heat resistance can be imparted without causing thermal deterioration due to PVC contact that tends to occur when mixed with an electric wire containing PVC resin.

  Examples of phenolic antioxidants include triethylene glycol-bis (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate), 1,6-hexanediol-bis (3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate), pentaerythrityl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5, -di-t-butyl-4-hydroxybenzyl) benzene, Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, isooctyl-3- (3,5-di-t-butyl-4-hydroxy Roxyphenyl) propionate, etc. Among them, 3,5-di-t-butyl-4-hydroxyphenyl group or 3,5-di-t- from the point of imparting high heat resistance to the composition and the electric wire Those having two or more butyl-4-hydroxybenzyl groups are preferred, and tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate is particularly preferred.

Examples of the benzimidazole antioxidant include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 4-mercaptomethylbenzimidazole, 5-mercaptomethylbenzimidazole, and zinc salts thereof.
Examples of thioether-based antioxidants include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, pentaerythritol tetrakis (3- Among them, pentaerythritol tetrakis (3-lauryl thiopropionate) is preferable from the viewpoint of imparting high heat resistance to the composition and the insulated wire.

In heat-resistant electric wires used for automobiles and the like, it is common to crosslink a composition covering a conductor by an electron beam cross-linking method from the viewpoint of productivity, and peroxy radicals or hydroperoxides during electron beam irradiation. Occurs in a large amount, which causes a problem of consuming a large amount of the antioxidant added to the composition.
For this reason, the amount of the antioxidant added to the composition of the present invention is 10 times or more that of the antioxidant added to the general non-crosslinked composition.

The blending amount of the phenolic antioxidant and the benzimidazole antioxidant in the present invention is such that an ethylene / vinyl acetate copolymer or ethylene / vinyl acetate content is 10% by mass or more and less than 40% by mass alone or in a mixture. The phenolic antioxidant is 2 to 10 parts by weight, preferably 4 to 8 parts by weight, and the benzimidazole antioxidant is 10 to 25 parts by weight with respect to 100 parts by weight of the mixture of the vinyl acetate copolymer and the polyolefin. The amount is preferably 10 to 20 parts by mass.
When the blending amount of the phenolic antioxidant is less than 2 parts by mass, the effect of improving the heat resistance is not observed in the composition after crosslinking and the electric wire coated therewith, and when the amount exceeds 10 parts by mass, the heat resistance is improved. The effect may be saturated, or the tensile properties may be reduced due to cross-linking inhibition.

The benzimidazole antioxidant can further improve the heat resistance of the composition after crosslinking and the electric wire coated therewith in combination with the phenol antioxidant, but its melting point is around 300 ° C. For this reason, when the blending amount is large, poor dispersion may occur in the composition and the tensile properties may be lowered.
For this reason, as described above, the melt flow rate (MFR) of the ethylene / vinyl acetate copolymer or polyolefin as the resin component is preferably 0.1 to 10 g / 10 min, more preferably 0.5 to 5 g / 10. It is effective to increase the melt viscosity of the resin and improve the kneadability within a range in which the load on the kneading equipment or extruder, which is a molding device for the composition or insulated wire, does not increase.
However, when the blending amount of the benzimidazole antioxidant is less than 10 parts by mass, a high heat resistance life of 120 ° C. × 10,000 hours and 150 ° C. × 10000 hours can be obtained in the composition after crosslinking and the electric wire coated therewith. However, when the amount exceeds 25 parts by mass, the tensile properties may be deteriorated.

The thioether-based antioxidant can improve the heat resistance of the composition due to a synergistic effect when used in combination with the phenol-based antioxidant.
Many thioether-based antioxidants are liquid and those having a low melting point of about 30 to 70 ° C., and dispersibility in the composition is improved. There exists a problem that it precipitates easily and impairs the external appearance of an insulated wire, or reduces the adhesive force between a conductor and an insulator remarkably.
The blending amount of the thioether-based antioxidant in the present invention is an ethylene / vinyl acetate copolymer or an ethylene / vinyl acetate copolymer and a polyolefin having a vinyl acetate content of 10% by weight or more and less than 40% by weight alone or in a mixture. 0 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the mixture.
By blending a thioether-based antioxidant into the composition, higher heat resistance can be imparted, but when the blending amount exceeds 10 parts by mass, bleeding occurs, so in the insulated wire, the pulling force between the conductor and the insulator This is not preferable because a phenomenon of blooming on the surface due to a decrease in temperature or a change in ambient temperature is observed.

  In the composition of the present invention, various additives commonly used in electric wires and cables, for example, antioxidants, metal deactivators, ultraviolet absorbers, dispersants, pigments, etc. As long as the purpose is not impaired, it can be blended as needed.

The electric wire (insulated electric wire) of the present invention is obtained by subjecting a composition containing the above components (a) to (f), which has been melt-kneaded by a commonly used kneading apparatus such as a Banbury mixer, kneader, roll, etc. It can be manufactured by extrusion coating around a conductor using a machine and then crosslinking the coating layer.
The crosslinking method is not particularly limited and can be performed by either chemical crosslinking method or electron beam crosslinking method, but from the viewpoint of productivity, the crosslinking method by electron beam irradiation is preferable.
In the production of the insulated wire of the present invention, when crosslinking is performed by electron beam irradiation, the dose of the electron beam is preferably 50 to 250 kGy, and in order to efficiently perform crosslinking, a methacrylate compound, an allyl compound, a maleimide compound, You may mix | blend polyfunctional compounds, such as a divinyl type compound, as a crosslinking adjuvant.

The conductor diameter of the insulated wire of the present invention, the material of the conductor, and the like are not particularly limited, and are appropriately determined depending on the application.
The thickness of the insulator (coating layer) is not particularly limited, and may be the same as a normal one.
Further, the coating layer may have a multilayer structure, such as providing an intermediate layer between the insulator formed of the above composition and the conductor.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

Each component was kneaded with a Banbury mixer at the ratio shown in Tables 1 and 2, and further formed into a sheet with a roll, and then formed into a sheet with a thickness of 1 mm with a heated press facility.
Next, the molded sheet was irradiated with an electron beam with an irradiation amount of 120 kGy.
In addition, a composition obtained by kneading each component with a Banbury mixer is applied to a bare annealed copper wire having a conductor diameter of 5.0 mm (structure: 7 wires / 22 wires / element wire diameter: 0.32 mm) with an insulation thickness of 1.0 mm and an outer diameter. After extrusion to 7.0 mm, electron beam irradiation was performed at an irradiation dose of 120 kGy. The following test was implemented about the obtained sheet | seat and electric wire.
In addition, the following was used as each component of Table 1 and Table 2.
(1) Ethylene / vinyl acetate copolymer Evaflex V527-4 (trade name, manufactured by Mitsui / DuPont Polychemicals)
Vinyl acetate content 17% by mass
MFR 0.8g / 10min
(2) Ethylene / vinyl acetate copolymer V220 (trade name, manufactured by Ube Maruzen Polyethylene)
Vinyl acetate content 20% by mass
MFR 2.0g / 10min
(3) Ethylene / vinyl acetate copolymer EVAFLEX EV40LX (trade name, manufactured by Mitsui / DuPont Polychemicals)
Vinyl acetate content 41% by mass
MFR 2.0g / 10min
(4) Modified polyethylene Adtex L6100M (trade name, manufactured by Nippon Polyolefin)
MFR 1.0g / 10min
(5) Low density polyethylene UBEC130 (trade name, manufactured by Ube Maruzen Polyethylene)
MFR 0.28g / 10min
(6) Silane coupling agent treated aluminum hydroxide Heidilite H42STV (trade name, manufactured by Showa Denko KK)
Vinylsilane-treated aluminum hydroxide
(7) Magnesium hydroxide treated with silane coupling agent Kisuma 5L (trade name, manufactured by Kyowa Chemical Co., Ltd.)
Vinylsilane-treated magnesium hydroxide
(8) Aluminum hydroxide Heidilite H42M (trade name, Showa Denko)
(9) Silane coupling agent KBE502 (trade name, manufactured by Shin-Etsu Silicone)
3-Methacryloxypropylmethyldiethoxysilane
(10) Phenolic antioxidant Irganox 1010 (trade name, manufactured by Ciba Specialty Chemicals)
Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
(11) Benzimidazole antioxidant NOCRACK MBZ (trade name, manufactured by Ouchi Shinko Chemical Co., Ltd.)
Zinc salt of 2-mercaptobenzimidazole
(12) Thioether antioxidant ADK STAB AO-412S (trade name, manufactured by Asahi Denka Co., Ltd.)
Pentaerythritol-tetrakis (3-laurylthiopropionate)
(13) Crosslinking aid Ogmont T-200 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Trimethylolpropane trimethacrylate
(14) Lubricant Sinaka Red ZS-101 (trade name, manufactured by Shinagawa Chemical Industries)
Zinc stearate

Tensile properties The obtained sheet was punched into a dumbbell shape No. 4 punching die defined by JIS K6301 and measured at a marked line of 20 mm and a tensile speed of 200 mm / min.
JIS K6301 requires a tensile strength of 10.3 MPa or more and an elongation of 150% or more.

Heat resistance The obtained sheet was punched into a dumbbell shape No. 4 punching die specified in JIS K6301 and punched into a dumbbell shape, exposed to a constant temperature bath at 180 ° C. for 30 days, and then measured at a marked line of 20 mm and a tensile speed of 200 mm / min. Carried out.
When the tensile elongation after 180 ° C x 30 days is 100% or more, it is known by the extrapolation prediction by Arrhenius plot that it corresponds to a heat resistant life of 150 ° C x 10,000 hours, and the tensile elongation is required to be 100% or more. The

Heat resistance (PVC tape compatibility)
The obtained electric wire is cut to about 600 mm, and the heat-resistant PVC tape is spirally wound over the entire length so that 1/3 of the tape width overlaps, and exposed to a constant temperature bath at 180 ° C. for 15 and 30 days. The PVC tape was removed and wound around the mandrel having the same outer diameter (7.0 φmm) as that of the electric wire for 6 turns, and the surface of the insulator was checked for cracks. Those that do not have cracks or cracks are accepted and required to pass at 180 ° C. for 15 days.

Flame retardancy About the obtained electric wire, the flame retardance and the horizontal test prescribed | regulated to JISC3005 were implemented, and what passed was described as (circle) and the thing rejected was described as x.

Electric wire characteristics (insulator adhesion)
The obtained electric wire was cut to a length of about 150 mm, and a sample was obtained by removing the coating from the terminal portion on one side, leaving an insulator having a length of 50 mm, and having a hole larger than the outer diameter of the conductor and smaller than the outer diameter of the insulator. Only the conductor part of the sample is passed through the jig, and the conductor is pulled out at 200 mm / min with the jig fixed, and the force until the conductor completely separates from the coating is measured. did.
If the adhesion is excessive, the insulation does not pull out when removing the sheath to crimp the terminal etc. to the end of the insulated wire, and if it is too small, the insulator moves in the longitudinal direction of the wire and the conductor is exposed. And since it may cause a short circuit, it is required to be 7N or more and 50N or less.

  The sheets and insulated wires shown in Examples 1 to 6 in Table 1 all had good mechanical characteristics, heat resistance characteristics, flame retardancy, and insulation pull-out force.

On the other hand, for Comparative Example 1 in Table 2, the vinyl acetate content in the resin mixture of the composition was 8.5% by mass, and the vinyl acetate content was too low. Even if 160 parts by mass is blended, the flame retardancy is rejected.
For Comparative Example 2, the total amount of the resin of the composition is composed of an ethylene / vinyl acetate copolymer having a vinyl acetate content of 41% by mass, and the tensile strength decreases because the vinyl acetate content is excessive. It is less than 10.3 MPa and it is rejected.
About the comparative example 3, since there are too few compounding quantities of a metal hydrate, a flame retardance is disqualified.
About Comparative Example 4, since the compounding quantity of a metal hydrate is excessive, tensile elongation falls and it is less than 150% and is disqualified.
In Comparative Examples 5 and 6, because the addition amount of benzimidazole antioxidant and phenolic antioxidant is too small, the tensile elongation after 180 ° C. × 30 days is less than 100%, and the heat resistance is insufficient. ing.
In Comparative Examples 7 and 8, the amount of addition of benzimidazole antioxidant and phenolic antioxidant is excessive, so that Comparative Example 7 has a tensile elongation decreased due to poor dispersion, and is less than 150%. ing. About comparative example 8, tensile strength falls by bridge | crosslinking inhibition, and it is less than 10.3 Mpa, and is rejected.
About Comparative Example 9, since the addition amount of the thioether-based antioxidant is excessive, bleeding occurs, the adhesion between the conductor and the insulator becomes excessively low, and it is rejected.
For Comparative Examples 10 and 11, the tensile elongation after 180 ° C. × 30 days is less than 100%, the heat resistance is insufficient, and the heat-resistant life is rapidly reduced in the state of contact with the PVC tape. became.

Claims (4)

  With respect to 100 parts by mass of (a) an ethylene / vinyl acetate copolymer or (b) a mixture of an ethylene / vinyl acetate copolymer and a polyolefin having a vinyl acetate content of 10% by mass or more and less than 40% by mass ( c) 50 to 160 parts by mass of metal hydrate, (d) 2 to 10 parts by mass of phenolic antioxidant, (e) 10 to 25 parts by mass of benzimidazole antioxidant, (f) thioether antioxidant 0 A flame retardant resin composition containing 10 to 10 parts by mass.   The flame retardant resin composition according to claim 1, wherein the metal hydrate (c) is surface-treated with a silane coupling agent.   The flame retardant resin composition according to claim 1 or 2, wherein the metal hydrate (c) is aluminum hydroxide, magnesium hydroxide, or a mixture of aluminum hydroxide and magnesium hydroxide.   The electric wire characterized by coat | covering the conductor with the flame-retardant resin composition described in any one of Claims 1-3, and carrying out the crosslinking process.