JP2020140840A - Insulated electric wire and cable - Google Patents

Abstract

To provide an insulated electric wire having good flame retardance, oil resistance, fuel resistance and low temperature characteristics, and obtained using a non-halogen resin composition, and a cable.SOLUTION: An insulated electric wire 11 has a conductor 11a, an inner layer 11b and an outer layer 11c, wherein the inner layer is formed of a resin composition including a first base polymer and a filler, and the outer layer is formed of a resin composition including a second base polymer and a metal hydroxide. The second base polymer includes at least two polymers of an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more and a polyolefin-based polymer having a melting point of 85°C or higher, the two kinds of polymers account for 80% or more of the second base polymer, and 150-250 pts.wt. of the metal hydroxide is included with respect to 100 pts.wt. of the base polymer.SELECTED DRAWING: Figure 1

Description

The present invention relates to an insulated electric wire and a cable using a non-halogen resin composition.

Due to the worldwide increase in environmental conservation activities in recent years, non-halogen materials that do not generate toxic gas during combustion and have less environmental pollution during disposal are rapidly becoming widespread.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2010-97881), a conductor is coated, an inner layer having an insulating property containing an ethylene ethyl acrylate copolymer (EEA), and an inner layer are coated, and ethylene acetic acid is used. An insulated wire containing a vinyl copolymer (EVA) and a non-halogen flame retardant and provided with an outer layer that is crosslinked and has oil resistance and flame retardancy is disclosed.

However, since non-halogen materials are generally inferior in flame retardancy as compared with halogen materials, it is necessary to highly fill them with a flame retardant in order to impart high flame retardancy. For example, in order to satisfy the standards requiring very high flame retardancy such as EN455545 and NFPA130, it is necessary to add about 200 parts by mass or more of the flame retardant. By adding such a flame retardant, the flame retardancy is improved, but other properties such as elongation property and low temperature property of the material tend to be deteriorated.

Further, since a flame retardant such as a metal hydroxide has high hygroscopicity, it may be difficult to maintain the required insulation performance due to deterioration of electrical characteristics when a large amount is added.

On the other hand, insulated electric wires and cables used in railway vehicles and the like are required to have high flame retardancy, electrical insulation, and fuel resistance depending on the environment in which they are used. For example, in the fuel resistance test specified in EN60811-2-1, the material is immersed in IRM903 oil at 70 ° C., and the rate of change in tensile strength and elongation of the material is measured.

As a method of achieving both high flame retardancy, electrical insulation and fuel resistance, a method in which the outer layer is a layer having high flame retardancy and fuel resistance and the inner layer is a layer having high electrical insulation is conceivable.

JP-A-2010-97881

The present inventor is engaged in research and development of coating materials such as the outer layer of cables and the insulating layer of electric wires, and uses a non-halogen material as the polymer as the coating material, which is flame-retardant and oil-resistant. , We are studying resin compositions with good fuel resistance and low temperature characteristics.

In particular, insulated electric wires and cables used for railway vehicles and the like are required to have high flame retardancy and electrical insulation, as well as fuel resistance characteristics depending on the environment in which they are used.

In order to improve the fuel resistance, it is effective to use a polymer that does not melt at the test temperature of 70 ° C. or a polymer that is difficult to be compatible with IRM903 oil. The use of the former polymer is effective in improving fuel resistance, but the elongation characteristics and the like are significantly reduced due to the addition of flame retardants, etc., and extremely high flame retardancy such as EN45545 and NFPA130 is required. If this is the case, it is difficult to achieve both flame retardancy and various physical properties such as elongation characteristics.

As the latter polymer that is incompatible with IRM903 oil, a polymer having a high polarity is effective. However, as described above, it is difficult for a product having a high melting point to have both flame retardancy and various physical properties such as elongation characteristics. Examples of polymers having a low melting point and high polarity include EVA having a high VA amount and EEA having a high EA amount. Considering availability in the market, high VA EVA having many grades on the market is suitable. ing. However, high VA EVA generally has poor tensile strength and severe fusion between polymers, so that it is not suitable for single use.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulated wire and cable using a non-halogen resin composition having good flame retardancy, oil resistance, fuel resistance, and low temperature characteristics. And.

(1) The insulated wire according to one aspect of the present invention is an insulated wire having a conductor, a first insulating layer covering the conductor, and a second insulating layer covering the first insulating layer. The first insulating layer comprises a first non-halogen resin composition containing a first base polymer and a filler, and the second insulating layer is a second non-halogen resin containing a second base polymer and a metal hydroxide. The second base polymer comprises at least 2 of an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA content) of 60% or more and a polyolefin polymer having a melting point of 85 ° C. or higher. The two types of polymers account for 80% or more of the second base polymer, and the metal hydroxide is contained in a ratio of 150 to 250 parts by weight with respect to 100 parts by weight of the base polymer.

(2) For example, the first base polymer contains 50% or more of polyethylene having a melting point of 110 ° C. or higher, and the filler is contained in a ratio of 150 parts by weight or less with respect to 100 parts by weight of the base polymer.

(3) For example, the filler is calcined clay or talc.

(4) For example, the tensile strength after cross-linking is 10 MPa or more and the elongation is 150% or more, and the rate of change in tensile strength after immersion in IRM903 oil at 70 ° C. for 168 hours is within ± 30%. The rate of change in elongation is within ± 40%.

(5) For example, an acid-modified polyolefin is mixed with the first base polymer.

(6) For example, the acid-modified polyolefin is mixed with the second base polymer, and the glass transition temperature (Tg) of the acid-modified polyolefin is −55 ° C. or lower, and the two types of polymers and the above. The mass ratio with the acid-modified polyolefin is 80:20 to 99: 1.

(7) For example, the metal hydroxide contains magnesium hydroxide or aluminum hydroxide, and the polyolefin-based polymer having a melting point of 85 ° C. or higher is an ethylene-vinyl acetate copolymer (EVA).

(8) The cable of one aspect of the present invention is a cable having the insulated wire and a sheath that covers the insulated wire.

(9) The cable according to one aspect of the present invention is a cable having an insulated wire and a sheath for coating the insulated wire, and the sheath is made of a non-halogen resin composition containing a base polymer and a metal hydroxide. The base polymer comprises at least two polymers, an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more and a polyolefin polymer having a melting point of 85 ° C. or more. The two types of polymers account for 80% or more of the base polymer, and the metal hydroxide is contained in a ratio of 150 to 250 parts by weight with respect to 100 parts by weight of the base polymer.

(10) For example, the tensile strength after cross-linking is 10 MPa or more and the elongation is 150% or more, and the rate of change in tensile strength after immersion in IRM903 oil at 70 ° C. for 168 hours is within ± 30%. The rate of change in elongation is within ± 40%.

According to the insulated electric wire and cable using the non-halogen resin composition according to one aspect of the present invention, flame retardancy, oil resistance, fuel resistance, and low temperature characteristics can be improved.

It is sectional drawing which shows the structural example of an insulated electric wire. It is sectional drawing which shows the structural example of a cable.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a configuration example of an insulated wire according to the present embodiment. The insulated wire 11 shown in FIG. 1 has a conductor 11a, an inner layer 11b, and an outer layer 11c.

As the conductor 11a, a metal wire, for example, a copper wire, a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. Further, the outer circumference of the metal wire may be plated with a metal such as tin or nickel. As the conductor 11a, a plurality of metal wires may be used, or stranded wires may be used.

As the inner layer (insulating layer) 11b, a resin composition containing a base polymer, a filler, and other additives can be used.

(Base polymer)
As the base polymer, polyethylene (polyolefin), which is a polymer having excellent electrical insulation, can be used. As the polyethylene, it is preferable to use polyethylene having a melting point of 110 ° C. or higher. The melting point can be measured by the differential scanning calorimetry (DSC) method. If the melting point is lower than 110 ° C., the crystals will melt during the oil resistance test, making it difficult to prevent the oil from diffusing into the polymer, and the rate of change in tensile properties will increase.

In order to improve the crystallinity, it is preferable to add crystalline polyethylene (polyolefin) having a melting point of 120 ° C. or higher.

Examples of polyethylene having a melting point of 110 ° C. or higher include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. The ratio of polyethylene having a melting point of 110 ° C. or higher in the base polymer is preferably 50% (50% by weight) or more, and more preferably 60 to 80%. As described above, the base polymer contains polyethylene having a melting point of 110 ° C. or higher as a main component.

Considering the acceptability of the filler, it is preferable that the base polymer contains a rubber component. That is, the rubber component causes the interface between the polyethylene (polyolefin) and the filler to be in close contact with each other, and peeling of the polyethylene (polyolefin) and the filler can be prevented.

The rubber components include ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene ternary copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (HNBR), acrylic rubber, and ethylene. -Acrylic acid ester copolymer rubber, ethylene octene copolymer rubber (EOR), ethylene-vinyl acetate copolymer rubber, ethylene-butene-1 copolymer rubber (EBR), butadiene-styrene copolymer rubber (SBR) ), Isobutylene-isoprene copolymer rubber (IIR), block copolymer rubber containing a polystyrene block, urethane rubber and the like. Among them, EOR and EBR do not have a double bond, so there is no risk of scorch at the time of extrusion, and since they do not have polarity, high electrical characteristics can be obtained. As described above, it is preferable to use EOR or EBR as the rubber component.

Further, it is preferable to use an acid-modified polyolefin (polyolefin modified with acid) in order to obtain high electrical properties. Examples of the acid used as a material for the acid-modified polyolefin include maleic acid, maleic anhydride, fumaric acid and the like. Examples of the polyolefin used as a material for the acid-modified polyolefin include polyethylene, ethylene-α-olefin, ethylene-ethylacrylate copolymer, ethylene-methylacrylate copolymer, and vinyl acetate copolymer. Above all, it is preferable to use an acid-modified polyolefin having a glass transition temperature (Tg) of −55 ° C. or lower.

(filler)
A filler is added to the base polymer. Here, in the present specification, the filler refers to an inorganic substance added to the base polymer, which is added at least 20 parts by weight or more with respect to 100 parts by weight (mass part) of the base polymer. However, if the amount of the filler is too large, the elongation at break decreases. Therefore, the amount of the filler added is preferably 150 parts by weight or less per 100 parts by weight of the base polymer.

It is not necessary to add a filler, but the addition of the filler can reduce the proportion of organic substances in the resin composition. By reducing the proportion of organic substances (polymers and rubber components), toxic gases such as carbon monoxide and carbon dioxide generated during combustion can be reduced. The amount of the filler added is more preferably 20 to 130 parts by weight, still more preferably 50 to 100 parts by weight, per 100 parts by weight of the base polymer.

Examples of the filler include oxidation of kaolinite, kaolin clay, calcined clay, talc, mica, wollastonite, pyrophyllite and other silicates, silica, alumina, zinc oxide, titanium oxide, calcium oxide and magnesium oxide. Examples include substances, carbonates such as calcium carbonate, zinc carbonate and barium carbonate, and hydroxides such as calcium hydroxide, magnesium hydroxide and aluminum hydroxide. These materials may be used alone or in combination of two or more.

Among the above materials, hydrophobic fired clay and talc not only exhibit high electrical properties but also do not contain carbon, so that carbon monoxide generation can be suppressed, and they are preferable for use as a filler. Further, as the filler, a surface-treated material may be used. For example, the above material may be surface-treated with silane. By surface-treating the silane, the adhesion between the filler and the polymer can be strengthened, and the insulation performance can be improved.

(Other additives)
The resin composition may include cross-linking aids, flame retardant aids, UV absorbers, light stabilizers, softeners, lubricants, colorants, reinforcing agents, surfactants, plasticizers, metal deactivators, as required. Foaming agents, compatibilizers, processing aids, stabilizers and the like can be added.

As the outer layer (insulating layer) 11c, a non-halogen resin composition containing a base polymer, a filler, and other additives can be used.

(Base polymer)
The base polymer includes two types of polymers, an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more, and a polyolefin-based polymer having a melting point of 85 ° C. or more. The "two types of polymers" referred to here mean a group of polymers, and as an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more, a plurality of types of polymers are used. It may be contained, and a plurality of types of polymers may be contained as the polyolefin-based polymer having a melting point of 85 ° C. or higher. Further, the polyolefin-based polymer having a melting point of 85 ° C. or higher may be an ethylene-vinyl acetate copolymer (EVA).

The EVA amount is not particularly limited as long as the VA amount is 60% or more, but the low temperature characteristics tend to decrease as the VA amount increases. Therefore, when the low temperature characteristics are required, the VA amount is 60 to 80. It is preferably%, and more preferably 60 to 70%. “VA amount [%]” is the content of vinyl acetate in the ethylene-vinyl acetate copolymer. This VA amount can be measured based on JIS K7192.

The polyolefin polymer is not particularly limited as long as it has a melting point of 85 ° C. or higher, but is low density polyethylene (LDPE), linear low density polyethylene (LLDPE), linear ultra low density polyethylene (VLDPE), and high density polyethylene. Examples thereof include high density polyethylene (HDPE), polypropylene (PP), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA) and the like. Above all, it is preferable to use EVA having a melting point of 85 ° C. or higher. However, the higher the crystallinity, the lower the physical properties such as elongation with the addition of the filler. Therefore, it is more preferable to use EVA having a VA amount of about 17% and a melting point of about 89 ° C.

Both of the above two types of polymers are indispensable, and the ratio thereof is not particularly limited. However, EVA having a VA amount of 60% or more and a polyolefin polymer having a melting point of 85 ° C. or more are 1: 2 to 2. The ratio is preferably 2: 1 (the former is about 33% to 66%, the latter is about 66% to 33%), and 4: 6 to 6: 4 (the former is 40% to 60%, the latter is 60%). ~ 40%) is more preferable.

The base polymer may include other polymers. Other polymers can be added within the specified range. That is, two types of base polymers are an ethylene-vinyl acetate copolymer (EVA) having an essential vinyl acetate content (VA amount) of 60% or more and a polyolefin polymer having a melting point of 85 ° C. or more. Since 80% or more of the polymer is contained, other polymers can be contained in the remaining range of less than 20% and in a range not overlapping with the above two types of polymers. Other copolymers include, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), linear ultra-low-density polyethylene (VLDPE), high-density polyethylene (HDPE), polypropylene (PP), and ethylene-. Ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), ethylene-styrene copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-butene-1 copolymer, ethylene-butene-hexene Three-way copolymer, ethylene-propylene-diene ternary copolymer (EPDM), ethylene-octene copolymer (EOR), ethylene copolymer polypropylene, ethylene-propylene copolymer (EPR), poly-4-methyl -Penten-1, maleic acid graft low density polyethylene, hydrogenated styrene-butadiene copolymer (H-SBR), maleic acid graft linear low density polyethylene, ethylene and α-olefin having 4 to 20 carbon atoms Polymer, ethylene-styrene copolymer, maleic acid grafted ethylene-methylacrylate copolymer, maleic acid grafted ethylene-vinyl acetate copolymer, ethylene-maleic anhydride copolymer, ethylene-ethylacrylate-maleic anhydride tri Examples thereof include a former copolymer and an ethylene-propylene-butene-1 ternary copolymer containing butene-1 as a main component.

Further, as another polymer, acid-modified polyolefin (polyolefin modified with acid) may be used. In particular, it is preferable to use an acid-modified polyolefin having a glass transition temperature of −55 ° C. or lower. The glass transition temperature refers to the glass transition temperature measured by the DSC method. The acid-modified polyolefin is obtained by grafting or copolymerizing an acid such as maleic anhydride with a polyolefin. Polyolefins that are materials for acid-modified polyolefins include natural rubber, butyl rubber, ethylene propylene rubber, ethylene α-olefin copolymer, styrene butadiene rubber, nitrile rubber, acrylic rubber, silicone rubber, urethane rubber, polyethylene, polypropylene, and ethylene-vinyl acetate. Polymers, polyvinyl acetate, ethyl ethylene acrylate copolymers, ethylene acrylic acid ester copolymers, polyurethanes, ultra-low density polyethylenes, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butene- Examples thereof include 1 copolymer, ethylene-hexene-1 copolymer, and ethylene-octene-1 copolymer. In particular, it is preferable to use ethylene propylene rubber, an ethylene α-olefin copolymer, or an ethyl ethylene acrylate copolymer.

Examples of the acid that is the material of the acid-modified polyolefin include maleic anhydride, fumaric acid, and the like, in addition to maleic anhydride. These acid-modified polyolefins may be added alone or in combination of two or more.

The mass ratio of the two types of polymers to the acid-modified polyolefin is preferably 80:20 to 99: 1.

(filler)
A filler is added to the base polymer. A metal hydroxide is added as a filler. The metal hydroxide has a role as a flame retardant. Examples of the metal hydroxide include magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like. Of these, magnesium hydroxide is preferably used. Further, the above-mentioned metal hydroxide may be used alone or in combination of two or more. Further, as the metal hydroxide, those surface-treated with a silane coupling agent, a titanate-based coupling agent, a fatty acid such as stearic acid or calcium stearate, or a fatty acid metal salt may be used.

The amount of the metal hydroxide added is preferably 150 to 250 parts by weight, more preferably 180 to 220 parts by weight, per 100 parts by weight of the base polymer. If it is less than 150 parts by weight, sufficient flame retardancy cannot be obtained, and if it is more than 250 parts by weight, the elongation characteristics and the like are deteriorated.

(Other additives)
Other additives are added to the base polymer as needed. Other additives include antioxidants, metal deactivators, flame retardants other than the above metal hydroxides, cross-linking agents, cross-linking aids, lubricants, fillers other than the above fillers, compatibilizers, stabilizers, etc. Examples include carbon black and colorants.

Examples of the antioxidant include phenol-based, sulfur-based, amine-based, and phosphorus-based antioxidants.

Examples of the phenolic antioxidant include dibutylhydroxytoluene (BHT), pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], and 1,3,5-tris (3). , 5-Di-t-butyl-4-hydroxy-benzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, thiodiethylenebis [3- (3,5-di-tert-) Butyl-4-hydroxyphenyl) propionate] and the like. Of these, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is preferably used.

Examples of the sulfur-based antioxidant include didodecyl 3,3'-thiodipropionate, ditridecyl 3,3'-thiodipropionate, dioctadecyl 3,3'-thiodipropionate, and tetrakis [methylene-3-( Dodecylthio) Propionate] Methane and the like. Of these, tetrakis [methylene-3- (dodecylthio) propionate] methane is preferably used.

These antioxidants may be added alone or in combination of two or more.

The metal inactive agent has the effect of stabilizing metal ions by chelating and suppressing oxidative deterioration. Examples of the metal deactivator include N- (2H-1,2,4-triasole-5-yl) salicylamide, bis dodecanoate [N2- (2-hydroxybenzoyl) hydrazide], 2', 3-bis [ [3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionyl]] Propionohydrazide and the like can be mentioned. Of these, it is preferable to use 2', 3-bis [[3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionyl]] propionohydrazide.

Examples of flame retardants other than metal hydroxides include amorphous silica, zinc nitrate, zinc hydroxytinate, zinc borate, zinc oxide and other zinc compounds, calcium borate, barium borate, barium borate and the like. Examples thereof include boric acid compounds, phosphorus-based flame retardants, nitrogen-based flame retardants such as melamine cyanurate, and intumescent flame retardants composed of a mixture of a component that foams during combustion and a component that solidifies.

As the cross-linking aid, for example, trimethylolpropane trimethacrylate (TMPT) or triallyl isocyanurate (TAIC) is preferably used.

Examples of the lubricant include fatty acids, fatty acid metal salts, fatty acid amides and the like. Specifically, zinc stearate can be used. These lubricants may be added alone or in combination of two or more.

As the carbon black, for example, carbon black for rubber (N900-N100: ASTM D 1765-01) can be used.

As the colorant, for example, a color masterbatch for the outer layer 11c or the like can be used.

(Crosslink)
The inner layer 11b and the outer layer 11c used for the insulated wire are obtained by cross-linking a mixture (resin composition) of the above materials. Examples of the cross-linking method include an irradiation cross-linking method in which a mixture (resin composition) of the above materials is formed and then cross-linked by irradiating an electron beam, radiation, or the like. When carrying out the irradiation cross-linking method, a cross-linking aid may be added in advance to the mixture (resin composition) of the above materials. Moreover, you may use the chemical cross-linking method of cross-linking by heating. When carrying out the chemical cross-linking method, a cross-linking agent may be added in advance to the mixture (resin composition) of the above materials. An organic peroxide can be used as the cross-linking agent. As the organic peroxide, for example, 1,3-bis (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide (DCP) and the like can be used.

The inner layer 11b and the outer layer 11c may be crosslinked at the same time, or after the inner layer 11b is crosslinked, the outer layer 11c may be formed on the outer periphery thereof and crosslinked.

(Application example 1)
In FIG. 1, an example in which the conductor 11a is covered with an insulating layer having a two-layer structure (inner layer 11b and outer layer 11c) is shown, but the conductor 11a may be covered with a single-layer insulating layer. In this case as well, an insulated wire having good characteristics can be obtained by forming the single-layer insulating layer using the same material as the outer layer 11c described above.

(Application example 2)
Although the non-halogen resin composition applied to the insulated electric wire has been described as an example in FIG. 1 and the above application example 1, the non-halogen resin composition of the present embodiment may be used as the sheath of the cable.

FIG. 2 is a cross-sectional view showing a configuration example of the cable of Application Example 2. The cable 12 shown in FIG. 2 has two twisted insulated wires 11 (twisted wire, see FIG. 1) and a sheath (coating layer, coating layer) 12d provided on the outside of the stranded wire. As the material of the sheath 12d, the same material as the above-mentioned outer layer 11c can be used. The number of insulated wires 11 in the cable 12 may be one, or three or more. Further, a separator or a shield braid may be provided between the two twisted insulated wires 11 and the sheath 12d. The material of the separator is not particularly limited and may be provided inside or outside the shield braid.

The above-mentioned insulated wire and cable can be used as a non-halogen insulated wire or a non-halogen cable. As a specific application, for example, an application for a railway vehicle can be considered. That is, it can be used as a non-halogen insulated electric wire for railway vehicles and a non-halogen cable for railway vehicles.

[Example]
Hereinafter, the insulated electric wire using the non-halogen resin composition of the present embodiment will be described in more detail with reference to Examples.

An insulated wire using a non-halogen resin composition was produced as follows.

(Material name)
The materials used in Examples and Comparative Examples are shown in Tables 1 and 3. The specific material names are as shown below.
-PE ¹⁾ : "Evolu SP1510" manufactured by Prime Polymer (melting point 117 ° C)
-PE ²⁾ : "Evolu SP4030" manufactured by Prime Polymer (melting point 127 ° C)
・ EBR ³⁾ : "Toughmer DF840" manufactured by Mitsui Chemicals, Inc.
-Acid-modified polyolefin ⁴⁾ : "Toughmer MH7020" manufactured by Mitsui Chemicals, Inc. (glass transition temperature (Tg) ≤ -55 ° C)
-Baking clay ⁵⁾ : "Translink 37" manufactured by BASF
-Antioxidant ⁶⁾ : "AO-18" manufactured by ADEKA CORPORATION
-Copper damage inhibitor ⁷⁾ : "CDA-6" manufactured by ADEKA CORPORATION
-Glidant ⁸⁾ : "Zinc stearate" manufactured by Nitto Kasei Co., Ltd.
-EVA ⁹⁾ : "Lanxess 600" (VA amount: 60%, melting point: none)
-EVA ¹⁰⁾ : "Lanxess 800" (VA amount: 80%, melting point: none)
・ EVA ¹¹⁾ : “Evaflex V5274” manufactured by Mitsui / DuPont Polychemicals
(VA amount: 17%, melting point: 89 ° C)
・ EVA ¹²⁾ : “Evaflex P1007” manufactured by Mitsui / DuPont Polychemicals
(VA amount: 10%, melting point: 94 ° C.)
・ EEA ¹³⁾ : "Lexpearl A1150" manufactured by Japan Polyethylene Corporation
(EA amount: 15%, melting point: 100 ° C.)
-Acid-modified polyolefin ¹⁴⁾ : "Toughmer MH7020" manufactured by Mitsui Chemicals, Inc. (glass transition temperature (Tg) ≤ -55 ° C)
-Magnesium hydroxide ¹⁵⁾ : "Magnesium S4" manufactured by Konoshima Chemical Co., Ltd.
-Antioxidant ¹⁶⁾ : "AO-18" manufactured by ADEKA CORPORATION
・ Carbon black ¹⁷⁾ : "FT carbon" manufactured by Asahi Carbon Co., Ltd.
-Glidant ¹⁸⁾ : "Zinc stearate" manufactured by Nitto Kasei Co., Ltd.
-PE ¹⁹⁾ : "Evolu SP0510" manufactured by Prime Polymer (melting point 98 ° C)
・ EVA ²⁰⁾ : “Evaflex V9000” manufactured by Mitsui / DuPont Polychemicals
(VA amount: 41%, melting point: none)
・ EVA ²¹⁾ : “Evaflex EV260” manufactured by Mitsui and DuPont Polychemicals
(VA amount: 28%, melting point: 72 ° C)
(Making an insulated wire)
In Examples 1 to 10, the inner layer and the outer layer were produced with the formulations shown in Table 1 and in Comparative Examples 1 to 7 with the formulations shown in Table 3 (see FIG. 1). That is, the compounding material for the inner layer or the compounding material for the outer layer shown in Tables 1 and 3 was kneaded with a pressure kneader at a start temperature of 40 ° C. and an end temperature of 190 ° C. to pelletize the kneaded product. .. An insulated wire was formed using this pellet-shaped resin composition.

Here, a two-layer extrusion is performed using a 40 mm extruder to extrude an inner layer with a thickness of 0.3 mm and an outer layer with a thickness of 0.47 mm around a conductor using 37 tin-plated conductors with a diameter of 0.18 mm. The inner layer and the outer layer were formed at the same time. Then, the electron beam was irradiated with 7.5 MRad to crosslink the inner layer and the outer layer.

(1) Tensile test A conductor was pulled out from an insulated wire to prepare a tube composed of an inner layer and an outer layer. This tube was cut to obtain test pieces marked with a predetermined distance (interval). At room temperature (25 ° C.), the test piece was pulled at a displacement rate of 250 mm / min, and the load and elongation until fracture were measured. The tensile strength (unit [MPa]) was calculated from the above load. Further, the breaking elongation ((Lb-La / La) × 100 [%]) was calculated from the initial length (marked line distance) La and the elongation (length between the marked lines at the time of breaking) Lb. A tensile strength of 10 MPa or more and an elongation of 150% or more were evaluated as ◯ (pass).

(2) Fuel resistance test A conductor was drawn from an insulated wire to prepare a tube composed of an inner layer and an outer layer. This tube was cut to obtain test strips marked at predetermined intervals. The test piece was immersed in IRM903 test oil heated to 70 ° C. for 168 hours, left at room temperature for about 16 hours, the test piece was pulled at a displacement rate of 250 mm / min, and the load and elongation until breakage were measured. Oil resistance from the tensile strength (A1) and breaking elongation (B1) of the test piece before being immersed in the test oil, and the tensile strength (A2) and breaking elongation (B2) of the test piece after being immersed in the test oil. The rate of change in tensile strength ((A2-A1) / A1) × 100 [%]) and the rate of change in elongation at break with fuel ((B2-B1) / B1) × 100 [%]) were calculated. Those whose "tensile strength" or "break elongation" decreased after immersion were defined as "-(minus)". If the rate of change in fuel tensile strength (residual tensile strength) is within ± 30%, it is evaluated as ○ (pass), and if the rate of change in fuel breaking elongation (residual tensile strength) is within ± 40%, it is ○ ( Passed).

(3) Oil resistance test A conductor was pulled out from an insulated wire to prepare a tube composed of an inner layer and an outer layer. This tube was cut to obtain test strips marked at predetermined intervals. The test piece was immersed in IRM902 test oil heated to 100 ° C. for 72 hours and then left at room temperature for about 16 hours. The test piece was pulled at a displacement rate of 250 mm / min, and the load and elongation until breaking were measured. Oil resistance from the tensile strength (A1) and breaking elongation (B1) of the test piece before being immersed in the test oil, and the tensile strength (A2) and breaking elongation (B2) of the test piece after being immersed in the test oil. The rate of change in tensile strength ((A2-A1) / A1) × 100 [%]) and the rate of change in oil-resistant elongation at break ((B2-B1) / B1) × 100 [%]) were calculated. Those whose "tensile strength" or "break elongation" decreased after immersion were defined as "-(minus)". If the oil resistance tensile strength change rate (tensile strength residual rate) is within ± 30%, it is evaluated as ○ (pass), and if the oil resistance fracture elongation change rate (tensile elongation residual rate) is within ± 40%, it is ○ (pass). And said.

(4) Low temperature test A conductor was pulled out from the insulated wire to prepare a tube composed of an inner layer and an outer layer. This tube was cut to obtain test strips marked at predetermined intervals. The test piece was held at −40 ° C., the test piece was pulled at a displacement rate of 30 mm / min in an atmosphere of −40 ° C., and the elongation (L2) until fracture was measured. The low temperature elongation ((L2 / L1) × 100 [%]) was calculated from the initial length L1 and elongation L2. Those with a low temperature elongation of 30% or more were marked with ◯ (pass).

(5) Flame-retardant test (5-1) Vertical combustion test A vertical combustion test (VFT) was conducted as a flame-retardant test based on EN60332-1-2. An insulated wire with a length of 600 mm is cut out as a test piece, the test piece is kept vertical, the flame is applied for 60 seconds, and when the flame is removed, the one digested within 60 seconds is marked as ○ (pass), and 60 Those that did not digest within seconds were marked as x (failed).

(5-2) Vertical Tray Combustion Test A vertical tray combustion test (VTFT) was conducted in accordance with EN50266-2-4. Seven insulated wires with a length of 3.5 m were prepared and twisted to form a bundle of cores, and 11 bundles were arranged vertically at equal intervals. After burning for 20 minutes from the lower end, the flame was extinguished by itself, and the carbonization length from the lower end was measured. Those having a carbonization length of 2.5 m or less were evaluated as ◯ (pass), and those having a carbonization length of more than 2.5 m were evaluated as x (fail). Those having a carbonization length of 1.5 m or less were rated as ⊚ (excellent).

(6) Insulation test A DC stability test was conducted in accordance with EN50305 6.7. Those that did not break down were marked with ◯ (pass), and those that did not break down were marked with × (fail).

The test results of Examples 1 to 10 are shown in Table 2, and the test results of Comparative Examples 1 to 7 are shown in Table 4.

(Discussion)
The following matters are considered from the above-mentioned Examples and Comparative Examples.

As shown in Tables 1 and 2, in Examples 1 to 10, fuel resistance, insulation characteristics and other characteristics (tensile characteristics, oil resistance, low temperature characteristics, etc.) are also good while maintaining high flame retardancy. Was confirmed.

In Examples 2 and 4, in which the amount of the filler (inorganic filler) added to the inner layer is larger than that of Example 1, the tensile strength is improved as the amount of the filler added is increased. Further, the amount of the filler added was large, and 150 parts by weight was used. In Example 4, the vertical combustion test (VFT) was ○ (passed) and the vertical tray combustion test (VTFT) was ⊚ (excellent) in the flame retardancy test. ), And good results were obtained.

Compared with Example 1, in Example 3 in which a high melting point PE (melting point 127 ° C.) was used as the base polymer (polymer) of the inner layer, the oil resistance was improved.

In Examples 5 and 6 in which the flame retardant of the outer layer was added in an amount of 150 or 250 parts by weight, all the characteristics were good, and within the range of 150 to 250 parts by weight from the comparison with other Examples and Comparative Examples. If so, it was found that the amount of metal hydroxide added may be increased or decreased. It was found that the smaller the amount of metal hydroxide, the better the elongation property and the low temperature property, and the larger the amount, the better the flame retardancy.

It was found that the characteristics were also good in Examples 7 to 10 in which the polymer species and the addition amount of the outer layer were changed, and the low temperature characteristics were improved in Example 8 in which the addition amount of the acid-modified polyolefin was as large as 20 parts by weight.

On the other hand, in Comparative Example 1, polyethylene having a melting point of 110 ° C. or higher was not added to the inner layer, and the oil resistance was unacceptable. From this matter and other examples and comparative examples, it was found that it is preferable that the inner layer contains polyethylene having a melting point of 110 ° C. or higher. Further, it was found that it is more preferable that the inner layer is mixed with the acid-modified polyolefin.

In Comparative Example 2, polyolefin (EVA ¹⁰⁾ having a melting point of 85 ° C. or higher was not added to the outer layer, and the tensile strength and low temperature characteristics were unacceptable. Further, in Comparative Example 2, fusion (adhesion) between the wires was observed in the insulated wires after the two-layer extrusion and before the cross-linking. In Comparative Example 3, EVA having a VA amount of 60% or more was not added to the outer layer, and the elongation characteristics and flame retardancy were rejected. Fuel resistance was rejected in Comparative Example 4 in which neither polyolefin having a melting point of 85 ° C. or higher and EVA having a VA amount of 60% or higher was added, and Comparative Example 5 in which the total of the two types was less than 80% of the polymer weight. became. Based on these matters, at least two types of ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more and a polyolefin polymer having a melting point of 85 ° C. or more are used in the outer layer. It has been found that it is preferable to use a base polymer in which the polymer accounts for 80% or more of the total polymer.

Further, in Comparative Example 6 in which the metal hydroxide in the outer layer was as small as 120 parts by weight, the flame retardancy was rejected, and in Comparative Example 7 in which the metal hydroxide in the outer layer was as large as 280 parts by weight, the elongation characteristics and the low temperature characteristics were rejected. It became. From these matters and other examples, it was found that the amount of the metal hydroxide in the outer layer is preferably 150 to 250 parts by weight.

The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist thereof. For example, in the above embodiment, the insulated electric wire has been described as an example, but a cable may be manufactured and evaluated. For example, the structure inside the sheath can be pulled out from the cable and evaluated in the same manner as in the case of an insulated wire.

11 Insulated wire 11a Conductor 11b Inner layer 11c Outer layer 12 Cable 12d Sheath

Claims (10)

An insulated wire having a conductor, a first insulating layer covering the conductor, and a second insulating layer covering the first insulating layer.
The first insulating layer comprises a first non-halogen resin composition containing a first base polymer and a filler.
The second insulating layer comprises a second non-halogen resin composition containing a second base polymer and a metal hydroxide.
The second base polymer contains at least two types of polymers, an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more and a polyolefin-based polymer having a melting point of 85 ° C. or more. , The above two types of polymers account for more than 80% of the second base polymer.
An insulated wire in which the metal hydroxide is contained in a ratio of 150 to 250 parts by weight with respect to 100 parts by weight of the base polymer. In the insulated wire according to claim 1,
The first base polymer contains 50% or more of polyethylene having a melting point of 110 ° C. or higher, and the filler is contained in a ratio of 150 parts by weight or less with respect to 100 parts by weight of the base polymer. In the insulated wire according to claim 2,
The filler is an insulated wire, which is calcined clay or talc. In the insulated wire according to claim 2,
The tensile strength after cross-linking is 10 MPa or more, and the elongation is 150% or more.
An insulated wire having a tensile strength change rate of ± 30% or less and an elongation change rate of ± 40% or less after being immersed in IRM903 oil at 70 ° C. for 168 hours. In the insulated wire according to claim 2,
An insulated wire in which an acid-modified polyolefin is mixed with the first base polymer. In the insulated wire according to claim 2,
An acid-modified polyolefin is mixed with the second base polymer,
The glass transition temperature (Tg) of the acid-modified polyolefin is −55 ° C. or lower.
An insulated wire having a mass ratio of the two types of polymers to the acid-modified polyolefin of 80:20 to 99: 1. In the insulated wire according to claim 2,
The metal hydroxide contains magnesium hydroxide or aluminum hydroxide.
The polyolefin-based polymer having a melting point of 85 ° C. or higher is an insulated wire which is an ethylene-vinyl acetate copolymer (EVA). A cable having an insulated wire and a sheath that covers the insulated wire.
A cable having the insulated wire according to any one of claims 1 to 7 as the insulated wire. A cable having an insulated wire and a sheath that covers the insulated wire.
The sheath comprises a non-halogen resin composition containing a base polymer and a metal hydroxide.
The base polymer contains at least two types of polymers, an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content (VA amount) of 60% or more and a polyolefin-based polymer having a melting point of 85 ° C. or more. Two types of polymers account for more than 80% of the base polymer,
A cable in which the metal hydroxide is contained in a ratio of 150 to 250 parts by weight with respect to 100 parts by weight of the base polymer. In the cable according to claim 9,
The tensile strength after cross-linking is 10 MPa or more, and the elongation is 150% or more.
A cable having a tensile strength change rate of ± 30% or less and an elongation change rate of ± 40% or less after being immersed in IRM903 oil at 70 ° C. for 168 hours.

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