JP2000007852A - Resin composition for electric wire coating and insulated electric wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for electric wire coating colorable to an optional color in spite of a high level of flame retardance and excellent mechanical characteristics possessed thereby in use without causing the elution of heavy metal compounds or phosphorus compounds or generating a large amount of smoke or corrosive gasses at the time of disposal such as landifilling or combustion. SOLUTION: This resin composition for electric wire coating is obtained by compounding 100 pts.wt. of a resin component comprising 70-99.5 wt.% of an ethylene-vinyl acetate copolymer and 30-0.5 wt.% of a modified polyolefin resin modified with an unsaturated carboxylic acid or its derivative with 180-250 pts.wt of magnesium hydroxide. The resin component contains >=50 wt.% of the ethylene-vinyl acetate copolymer with 27-43 wt.% content of the vinyl acetate component and further has 31.5-42 wt.% content of the vinyl acetate component in the resin component. The insulated electric wire is obtained by coating a conductor with a cross-linked composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for covering an insulated wire used for internal and external wiring of electric / electronic equipment, and to an insulated wire covered with the composition. The present invention relates to a resin composition for covering electric wires, which does not elute heavy metal compounds and does not generate a large amount of smoke or corrosive gas at the time of disposal such as combustion, and an insulated wire coated with the same.

[0002]

2. Description of the Related Art Polyvinyl chloride (PVC) compounds and halogen-based flame retardants containing bromine atoms and chlorine atoms in the molecule are used as covering materials for insulated wires used for internal and external wiring of electric / electronic devices. It is well known to use a resin composition containing a blended ethylene copolymer as a main component. However, if these materials are disposed of without proper treatment, the plasticizers and heavy metal stabilizers contained in the coating materials will elute, and if they are burned, corrosive gases will be generated from the halogen compounds contained in the coating materials. And dioxins may be generated, and in recent years, this problem has been discussed. For this reason, a technique for coating an electric wire with a non-halogen flame-retardant material that is not likely to elute harmful heavy metals or generate a halogen-based gas has begun to be studied. Non-halogen flame-retardant materials exhibit flame retardancy by blending a flame retardant containing no halogen into the resin. Examples of the flame retardant include metal hydrates such as magnesium hydroxide and aluminum hydroxide. Examples of the resin include polyethylene, ethylene / 1-butene copolymer, ethylene / propylene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, and ethylene / propylene / diene terpolymer. Copolymers and the like are used.

On the other hand, electronic wire harnesses and other insulated wires for electric / electronic devices used in electronic devices have very strict flame-retardant standards from the viewpoint of safety, for example, UL15.
81 (Reference Standard for Wires, Cables and Flexible Cords)
for Electrical Wires, Cab
leds, and Flexible Cord
s)) and other vertical combustion tests (Verti
cal Flame Test) and flame retardancy that passes the VW-1 standard. Further, such an insulated wire has a 100% elongation from UL and electrical equipment control standards.
% And high mechanical properties of 10 MPa or more in mechanical strength. VW has been used for halogen-free flame retardant materials
It has been studied to provide a high flame retardancy such as -1, but in the case of a resin such as a polyethylene resin, a metal hydrate is highly filled (for example, a metal water is added to 100 parts by weight of a resin). However, even if the Japanese product is blended in an amount of 200 parts by weight or more, it is not compatible with VW-1 or the mechanical properties of the flame-retardant material are significantly reduced even if the flame retardancy is achieved.
To solve this problem, a small amount of the metal hydrate (for example, 100 parts by weight of the resin,
(Less than 0 parts by weight) and blending red phosphorus, and non-halogen flame-retardant materials having both high flame retardancy and mechanical properties are being studied.

[0004] By the way, the coating material of the insulated wire used for the electric / electronic equipment includes a material printed on the surface of the insulated wire and several types of the insulated wire for the purpose of distinguishing the type of the insulated wire and the connection portion. Color (eg white, black, rat, brown, red,
Orange, yellow, green, blue, etc.). BACKGROUND ART Insulated wires colored in white, which is easy to understand printed contents, or in any color that is easy to distinguish, are manufactured by extrusion-coating a resin composition colored in a target color on a conductor. However, non-halogen flame-retardant materials containing a metal hydrate and red phosphorus in order to achieve both high flame retardancy and mechanical properties cannot be colored white or any color due to the color development of red phosphorus. In addition, there is a problem that an insulated wire whose type and connection portion can be easily distinguished cannot be obtained. Furthermore, in the case of non-halogen flame-retardant materials using this red phosphorus and metal hydrate in combination, not only do large amounts of smoke are generated during combustion, but also if the burnt ash after burning is disposed of by landfill, the phosphorus component flows out. There is a risk of water pollution (plankton mass generation) in surrounding lakes and marshes.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and, when used, can be colored in any color while having high flame retardancy and excellent mechanical properties, and can be landfilled. An object of the present invention is to provide an electric wire coating resin composition and an insulated electric wire which do not elute heavy metal compounds or phosphorus compounds and do not generate a large amount of smoke or corrosive gas at the time of disposal such as combustion.

[0006]

Means for Solving the Problems We have conducted intensive studies to solve the above problems by using an ethylene copolymer and magnesium hydroxide as resin materials, and as a result, it has a predetermined vinyl acetate component content. According to the resin composition comprising the specific resin component and a predetermined amount of magnesium hydroxide, the ethylene vinyl acetate copolymer is used, and the content of the vinyl acetate component as the entire resin component is adjusted to a predetermined range. It has been found that an insulated wire having excellent mechanical properties and conforming to high flame-retardant properties VW-1 can be obtained. The present invention has been completed based on this finding.

That is, the present invention relates to (1) a polymer comprising 70 to 99.5% by weight of an ethylene-vinyl acetate copolymer and 30 to 0.5% by weight of a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof. 180 parts by weight of magnesium hydroxide to 250 parts by weight with respect to 100 parts by weight of
Parts by weight, wherein the resin component contains 50% by weight or more of an ethylene-vinyl acetate copolymer having a vinyl acetate component ratio of 27 to 43% by weight, and further includes a vinyl acetate component in the resin component. Content of 31.5 to 42% by weight
(2) a resin composition for covering electric wires,
The resin composition for covering electric wires according to (1), wherein at least 75 parts by weight of magnesium hydroxide is treated with a silane coupling agent, and (3) tin with respect to 100 parts by weight of the resin component. The resin composition for covering an electric wire according to (1), wherein 0 to 20 parts by weight of zinc acid or 0 to 20 parts by weight of zinc borate is blended, and (4) (1) and (2). Alternatively, the present invention provides an insulated wire characterized in that a conductor is coated with a crosslinked body of the resin composition described in (3).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the resin composition of the present invention will be described. The resin composition of the present invention comprises a resin component in which an ethylene-vinyl acetate copolymer and a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof are blended in a predetermined amount, respectively, and further a predetermined amount of water. Comprising magnesium oxide. Further, in the resin composition of the present invention, an ethylene-vinyl acetate copolymer having a predetermined vinyl acetate component content is used in an amount of 50% by weight or more of the resin component, and the vinyl acetate component content of the entire resin component is 3%.
The resin composition is defined so as to fall within a specific range of 1.5 to 41% by weight.

(A) Ethylene-vinyl acetate copolymer The resin composition of the present invention contains the ethylene-vinyl acetate copolymer in an amount of 70 to 99.5% by weight, preferably 80 to 99.5% by weight of the resin composition. It is used in an amount of 99% by weight. When the amount of the ethylene-vinyl acetate copolymer in the resin component is less than 70% by weight, the flame retardancy decreases. Furthermore, this ethylene-
As the vinyl acetate copolymer, one having a vinyl acetate component ratio (content) of 27 to 43% by weight is 50% of the resin component.
% Or more, preferably a vinyl acetate component having a content of 32 to 43% by weight is used in an amount of 50% by weight or more, more preferably 70% by weight or more. Content of vinyl acetate component 2
If the ethylene-vinyl acetate copolymer content of 7 to 43% by weight is less than 50% by weight in the resin component, the mechanical strength cannot be attained, and it complies with the high flame retardant standard VW-1. Impossible. For example, when an ethylene-vinyl acetate copolymer having a vinyl acetate component content of less than 27% by weight is used in an amount of more than 50% by weight in the resin composition, the flame retardancy is reduced. In order to satisfy the above condition, it is necessary to use a large amount of an ethylene-vinyl acetate copolymer having a high content of a vinyl acetate component in addition to the copolymer, but this significantly reduces the mechanical strength of the resin. On the other hand, an ethylene-vinyl acetate copolymer having a vinyl acetate component content of more than 43% by weight was 50% by weight.
When used in larger amounts, the mechanical strength is significantly reduced. As the ethylene-vinyl acetate copolymer, one that satisfies the above conditions may be used alone, or two or more types having different contents of the vinyl acetate component may be used in combination. The ethylene-vinyl acetate copolymer used in the present invention is not particularly limited in other physical properties and production methods as long as it satisfies the above conditions, but has a melt flow rate (MFR) of 0.5 to 0.5. 25 g / 10 min is preferable, and 0.8 to 5
g / 10 minutes is more preferred. When two or more ethylene-vinyl acetate copolymers are used in combination, it is preferable to use ones having similar MFR.

(B) Polyolefin resin modified with unsaturated carboxylic acid or derivative thereof The modified polyolefin resin modified with unsaturated carboxylic acid or derivative thereof (hereinafter also referred to as modified polyolefin resin) is not particularly limited, but is preferably used. Unsaturated carboxylic acids such as maleic acid, maleic anhydride or derivatives thereof and polyethylene resins (eg, LLDPE and VLDPE)
Low-density polyethylene) and modified polyolefin resins such as ethylene-based copolymer resins. LLDP with maleic acid or maleic anhydride
Particularly preferred is a modified polyethylene resin obtained by modifying E or VLDPE. Modified polyolefin resin, in the resin component,
It is used in an amount of 30 to 0.5% by weight, preferably 1 to 25% by weight in the resin component, although it depends on the amount of maleic acid modified.
Used in amounts. When the content of the modified polyolefin resin contained in the resin component exceeds 30% by weight, the flame retardancy is significantly reduced, and the elongation is significantly reduced. On the other hand, 0.
If it is less than 5% by weight, the elongation is significantly reduced. Further, by blending the modified polyolefin resin, the strength of the resin composition can be improved. Further, the modified polyolefin-based resin has an effect of alleviating a decrease in mechanical properties of the resin composition due to the addition of the metal hydrate. In the resin composition of the present invention, the content of the vinyl acetate component in the resin component is 31.5 to 42% by weight, preferably 33 to 41% by weight, and more preferably 34 to 40% by weight. Adjustment of the vinyl acetate component content of the resin component as a whole, for example, by adding a large amount of ethylene-vinyl acetate copolymer having a high vinyl acetate component content, to increase the amount of the vinyl acetate component in the resin component, Conversely, it can be carried out by lowering the content of the vinyl acetate component in the resin component by using a large amount of an ethylene-vinyl acetate copolymer or a modified polyolefin resin having a low content of the vinyl acetate component. If the content of the vinyl acetate component in the resin component is less than 31.5% by weight, it will not be compatible with high flame retardancy VW-1. If it is more than 42% by weight, the desired mechanical strength will not be satisfied.

(C) Magnesium Hydroxide The magnesium hydroxide is not particularly limited, but may be one treated with a fatty acid such as stearic acid or oleic acid as a surface treating agent, one treated with a phosphate ester, or silane. Those which have been subjected to a coupling agent treatment are preferred. These are already on the market, and those commercially available under the trade names of Kisuma 5A, Kisuma 5B, Kisuma 5J, Kisuma 5E and other trade names (Kyowa Chemical Co., Ltd.) can be used. The amount of the magnesium hydroxide is 180 to 250 parts by weight, preferably 200 to 230 parts by weight, based on 100 parts by weight of the resin component. If the amount is less than 180 parts by weight, the flame retardancy is significantly reduced, and if the amount exceeds 250 parts by weight, the mechanical strength is significantly reduced. Also, among the magnesium hydroxide used, 75 parts by weight or more based on 100 parts by weight of the resin component,
More preferably, 100 parts by weight or more of magnesium hydroxide is preferably magnesium hydroxide having been subjected to a silane coupling agent surface treatment. By using the magnesium hydroxide surface-treated with the silane coupling agent, the mechanical strength of the obtained wire covering insulating layer is significantly improved. In particular, when the magnesium hydroxide surface-treated with the silane coupling agent is the total amount of the magnesium hydroxide to be used, the effect of improving the mechanical properties becomes extremely large.

(D) Zinc stannate and zinc borate In the resin composition of the present invention, zinc stannate and zinc borate are added to the above (A), (B),
It is preferable to use it in combination with a system containing (C). As zinc borate, those having an average particle diameter of 5 microns or less, particularly preferably about 3 microns are preferable. The zinc borate may be a commercial product, for example alk Nex _{FRC-500 (2ZnO / 3B 2} O 3 · 3.5H 2
O), FRC-600 (trade name, distributor Mizusawa Chemical) and the like. As the zinc stannate, zinc stannate (ZnSnO ₃ ) and hydrated zinc hydroxystannate (ZnSn (OH) ₆ ) are preferable, and trade names Alkanex ZS and Alkanex ZHS (distributors)
Commercial products such as (Mizusawa Chemical) can be used. The amount of each of these zinc stannate and zinc borate is preferably 20 parts by weight or less based on 100 parts by weight of the resin component. If the amount exceeds 20 parts by weight, the mechanical strength of the obtained electric wire insulating layer is reduced. Further, it was confirmed that there was almost no decrease in mechanical strength in the range of 20 parts by weight or less.

The flame-retardant resin composition for covering electric wires of the present invention includes:
Various additives commonly used in electric wires and cables, such as antioxidants, metal deactivators, flame retardant (auxiliary) agents, fillers, lubricants, etc., do not impair the object of the present invention. It can be appropriately compounded within the range. Since the flame-retardant resin composition of the present invention, which does not contain red phosphorus and contains a resin component and a metal hydrate, is white, a color batch containing a colorant and a polyolefin-based resin as a base resin is used. By blending, it can be easily colored to any color. Antioxidants include amine-based antioxidants such as polymers of 4,4'-dioctyldiphenylamine, N, N'-diphenyl-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline. Agent, 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-
Phenolic antioxidants such as 2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis (2-methyl-4- (3-n-alkylthiopropionyloxy)- 5-t-butylphenyl) sulfide, 2-mercaptobenzimidazole and its zinc salt, and sulfur-based antioxidants such as pentaerythritol-tetrakis (3-lauryl-thiopropionate).

Examples of the metal deactivator include N, N'-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, 3- (N-salicyloyl) amino-1, 2,4-triazole, 2, 2'-
Oxamidobis- (ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) and the like. Further, as a flame retardant (auxiliary) agent and filler, carbon, clay, zinc oxide, tin oxide, titanium oxide, magnesium oxide, molybdenum oxide, antimony trioxide, silicone compound, quartz, talc, calcium carbonate, magnesium carbonate, boric acid Zinc, white carbon and the like. Examples of the lubricant include hydrocarbon-based, fatty acid-based, fatty acid amide-based, ester-based, alcohol-based, and metallic soap-based lubricants, among which "Wax E" and "Wax OP" (trade name, manufactured by Hoechst) and the like. Ester lubricants exhibiting both internal and external lubricity at the same time are preferred.

Next, the insulated wire of the present invention will be described. The insulated wire of the present invention has a coating layer made of the resin composition of the present invention on a conductor (for example, a single wire or stranded conductor made of soft copper or the like), and the coating layer is a crosslinked body of the resin composition. It is composed. In the insulated wire of the present invention, by forming the coating layer by crosslinking the resin composition, not only the heat resistance can be improved, but also the flame retardancy can be improved. As a crosslinking method, an electron beam crosslinking method or a chemical crosslinking method by a conventional method can be adopted. In the case of the electron beam crosslinking method, crosslinking is performed by irradiating an electron beam after extruding a resin composition constituting the coating layer to form a coating layer. The dose of the electron beam is suitably from 1 to 30 Mrad, and in order to carry out the crosslinking efficiently, the resin composition constituting the coating layer is added to a methacrylate compound such as trimethylolpropane trimethacrylate or an allylic compound such as triallyl cyanurate. A polyfunctional compound such as a compound, a maleimide compound or a divinyl compound may be blended as a crosslinking aid. In the case of the chemical crosslinking method, for example, dicumyl peroxide, di-t-
Butyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
An organic peroxide such as 3,1,3-bis (tert-butylperoxyisopropyl) benzene or t-butylcumyl peroxide is compounded as a crosslinking agent, extruded to form a coating layer, and then heated by a conventional method. Crosslinking is performed by the treatment. In the insulated wire of the present invention, the thickness of the insulating coating layer formed around the conductor is not particularly limited, but is usually 0.15 mm.
About 1 mm.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, numerals show a weight part unless there is particular description. (Examples 1 to 13 and Comparative Examples 1 to 11) First, the components shown in Tables 1 to 3 were dry-blended at room temperature and melt-kneaded using a Banbury mixer to prepare a resin composition for an insulating coating layer. did. Next, a conductor (conductor diameter: 0.95 mmφ tinned soft copper stranded wire)
Composition: 21 pieces / 0.18 mmφ) was coated with a resin composition for insulation coating previously melt-kneaded by extrusion.
Insulated wires corresponding to the respective examples and comparative examples were manufactured. The outer diameter was 2.64 mm. After coating, crosslinking was performed by irradiating an electron beam at 8 Mrad. For each of the obtained insulated wires, the tensile properties and the flame retardancy were evaluated.
Are also shown. Test methods and evaluation conditions are shown below. -Tensile properties (tensile strength, elongation at the time of certainty) The coating layer of each insulated wire is made into a tubular piece, and its tensile strength (tensile strength) (MPa) and elongation (%) are measured using a tensile tester to a distance of 25 mm between the marked lines. Tensile speed 500 mm / min. It measured on condition of. The required properties of tensile strength and elongation are 1
0 MPa or more and 100% or more. -Flame retardancy For each insulated wire, UL1581 vertical combustion test (V
The test was performed on 5 samples, and the ratio of the samples that passed the test was shown.

The following components were used as the components shown in Tables 1 to 3. (01) Ethylene-vinyl acetate copolymer (EVA) Vinyl acetate (VA) component content 33% by weight (02) Ethylene-vinyl acetate copolymer VA component content 41% by weight (03) Ethylene-vinyl acetate copolymer Merged VA component content 46% by weight (04) Ethylene-vinyl acetate copolymer VA component content 28% by weight (05) Ethylene-vinyl acetate copolymer VA component content 25% by weight (06) Ethylene-vinyl acetate copolymer Polymer VA component content 17% by weight (07) Maleic anhydride-modified LLDPE manufactured by Nippon Polyolefin Co., Ltd., trade name: Adtec L6100M (08) Silane coupling agent surface treatment magnesium hydroxide manufactured by Kyowa Chemical Co., Ltd. (10) Oleic acid surface treated magnesium hydroxide manufactured by Kyowa Chemical Co., Ltd. (11) Calcium stearate (12) Dart phenolic anti-aging agent Made by Ciba Geigy, trade name: Irganox 1010 (13) Trimethylolpropane trimethacrylate (TMPTM) Ogmont T-200 (trade name, manufactured by Shin-Nakamura Chemical) (14) Zinc borate Alkanex 500 (trade name) (15) Zinc stannate Alkanex ZHS (trade name, manufactured by Mizusawa Chemical)

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

As is clear from the results of Tables 1 to 3, insulated wires (Examples 1 to 13) using the resin composition of the present invention
It can be seen that the material is excellent in both mechanical properties such as elongation and tensile strength and flame retardancy. Particularly, when at least 75 parts by weight of magnesium hydroxide is used, the surface of which is treated with a silane coupling agent, the magnesium hydroxide is excellent in mechanical strength (Examples 1 to 13). In addition, as compared with Example 1, zinc stannate or zinc borate was added so that the maximum combustion time in the flame retardant VW-1 test was significantly shortened in Examples 11 and 12. Flame retardancy can be further improved while maintaining strength.
On the other hand, if the content of the vinyl acetate (VA) component in the resin component is less than 31.5% by weight, the desired flame retardancy cannot be achieved (Comparative Examples 1 and 2). The strength is significantly reduced (Comparative Examples 10 and 11). When the ethylene-vinyl acetate copolymer having a vinyl acetate component content of 27 to 43% by weight is less than 50% by weight in the resin component, there is a problem in flame retardancy and mechanical properties, and it is not practical. (Comparative Examples 1, 3, 4, and 7). If the amount of magnesium hydroxide is less than 180 parts by weight based on 100 parts by weight of the resin component, there is a problem in flame retardancy.
Exceeding parts by weight caused problems in mechanical properties (Comparative Examples 5 and 6). Also, if the maleic anhydride-modified LLDPE is less than 0.5% by weight in the resin component, problems occur in mechanical properties, and if it is more than 30% by weight, problems occur in flame retardancy and mechanical strength (Comparative Example 8, 9).

[0022]

According to the conventional flame-retardant composition which is non-halogen and does not contain a phosphorus compound, it is necessary to highly fill an inorganic hydrate such as magnesium hydroxide. The decline was a problem. On the other hand, the resin composition of the present invention, by selectively using a specific base resin, can achieve a balance between high flame retardancy and mechanical properties even when highly filled with magnesium hydroxide, It is suitable as a composition for a coating layer of an insulated wire. In addition, the insulated wire of the present invention has a coating layer made of a non-halogen flame-retardant material, and disposes of heavy metal compounds and generates a large amount of smoke and corrosive gas during disposal and disposal such as landfill and combustion. Absent. In addition, since phosphorus-based compounds are not used in addition to halogen-based compounds, care is taken not to pollute the surrounding environment such as lakes and marshes even when disposed by landfill. It is an electric wire that can be colored more freely. As described above, the insulated wire of the present invention is very useful as a wiring material for electric / electronic devices in consideration of environmental issues.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 7/295 H01B 7/34 B // (C08L 23/08 23:26) (72) Inventor Hitoshi Yamada 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F term (reference) 4J002 BB061 BB212 DE076 DE187 DK007 FB096 FD010 FD030 FD070 FD130 FD136 FD137 FD140 GQ01 5G305 AA02 AA14 AB15 AB25 CA54 CA04 CA55 CC03 CC11 CD06 CD13 5G315 CA03 CB01 CC08 CD04 CD14 CD17

Claims (4)

[Claims] An ethylene-vinyl acetate copolymer 70 to 9
180 parts by weight to 250 parts by weight of magnesium hydroxide are mixed with 100 parts by weight of a resin component consisting of 9.5% by weight and 30 to 0.5% by weight of a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof. The resin component has a vinyl acetate component ratio of 27 to 43% by weight.
Characterized in that the ethylene-vinyl acetate copolymer is 50% by weight or more, and the content of the vinyl acetate component in the resin component is 31.5 to 42% by weight. . 2. The resin composition according to claim 1, wherein at least 75 parts by weight of the magnesium hydroxide has been treated with a silane coupling agent. 3. The resin composition for covering electric wires according to claim 1, wherein 0 to 20 parts by weight of zinc stannate or 0 to 20 parts by weight of zinc borate is mixed with 100 parts by weight of the resin component. object. 4. An insulated wire comprising a conductor coated with a crosslinked body of the resin composition according to claim 1, 2 or 3.