CN111081412A

CN111081412A - Insulated wire

Info

Publication number: CN111081412A
Application number: CN201910920270.7A
Authority: CN
Inventors: 岩崎周; 木部有; 桥本充; 梶山元治
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2018-10-18
Filing date: 2019-09-26
Publication date: 2020-04-28
Anticipated expiration: 2039-09-26
Also published as: CN111081412B; JP7143720B2; JP2020064772A; DE102019127462A1

Abstract

Provided is an insulated wire which is excellent in flame retardancy, electrical insulation properties and oil resistance. The insulated wire includes a conductor, a first insulating layer covering the conductor, and a second insulating layer located on an outer peripheral side of the first insulating layer. The first insulating layer contains a first polymer and 150 parts by mass or less of an inorganic filler per 100 parts by mass of the first polymer. The second insulating layer is composed of a halogen-free flame-retardant resin composition containing a second polymer mainly composed of an ethylene-vinyl acetate copolymer and a metal hydroxide added in an amount of 150 to 250 parts by mass based on 100 parts by mass of the second polymer. The first polymer contains a polyolefin having a melting point of 110 ℃ or higher and an acid-modified polyolefin as main components of the first polymer. The first insulating layer and the second insulating layer are crosslinked.

Description

Insulated wire

Technical Field

The present invention relates to an insulated wire.

Background

The insulated wire is provided with a conductor and an insulating layer. The insulating layer covers the conductor. Insulated electric wires are used for railway vehicles and the like. The insulated wire is used, for example, as a power line wired in a motor or the like, a control line controlling operation, or the like. For insulated electric wires, excellent flame retardancy, electrical insulation properties, and oil resistance are required.

Patent document 1 discloses a technique for improving flame retardancy of an insulated wire by blending a polyolefin resin and a large amount of metal hydroxide in an insulating layer.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-18932

Disclosure of Invention

Problems to be solved by the invention

The metal hydroxide has high hygroscopicity. Therefore, if a large amount of metal hydroxide is mixed in the insulating layer as in the technique described in patent document 1, the electrical insulation of the insulated wire is degraded.

An object of one aspect of the present disclosure is to provide an insulated wire excellent in flame retardancy, electrical insulation, and oil resistance.

Means for solving the problems

One aspect of the present disclosure is an insulated electric wire provided with a conductor, the first insulating layer comprises a first polymer and an inorganic filler blended in an amount of 150 parts by mass or less per 100 parts by mass of the first polymer, the second insulating layer comprises a halogen-free flame-retardant resin composition comprising a second polymer mainly composed of an ethylene-vinyl acetate copolymer and a metal hydroxide blended in an amount of 150 parts by mass or more and 250 parts by mass or less per 100 parts by mass of the second polymer, the first polymer comprises a polyolefin having a melting point of 110 ℃ or more and an acid-modified polyolefin as main components of the first polymer, and the first insulating layer and the second insulating layer are crosslinked.

The insulated wire as one aspect of the present disclosure is excellent in flame retardancy, electrical insulation, and oil resistance.

Drawings

Fig. 1 is a sectional view showing the configuration of an insulated wire 1.

Fig. 2 is a sectional view showing the constitution of the insulated cable 9.

Description of the symbols

1: an insulated wire; 3: a conductor; 5: a first insulating layer; 7: a second insulating layer; 9: an insulated cable; 11: a sheath.

Detailed Description

Exemplary embodiments of the present disclosure are described with reference to the accompanying drawings.

1. Constitution of insulated wire

(1-1) conductor

The insulated wire is provided with a conductor. As the conductor, a known one can be appropriately selected and used. Examples of the material of the conductor include copper and aluminum.

(1-2) first insulating layer

The first insulating layer covers the conductor. The first insulating layer contains a first polymer. The first polymer contains a polyolefin as a main component of the first polymer (hereinafter referred to as a main component polyolefin). The main component of the first polymer means a component contained in the first polymer in the largest amount among polymer components. The first polymer may or may not contain a polyolefin other than the polyolefin as the main component.

The melting point of the polyolefin as the main component is 110 ℃ or higher. The melting point of the polyolefin as the main component is 110 ℃ or higher, so that the oil resistance of the first insulating layer is high. The melting point of the polyolefin as the main component is measured by Differential Scanning Calorimetry (DSC).

The oil resistance can be evaluated by the following method. The test bodies were soaked in IRM902 test oil heated to 100 ℃ for 72 hours. The smaller the change rate of the tensile property of the test piece after soaking with respect to the tensile property of the test piece before soaking (hereinafter referred to as the change rate of the oil-resistant tensile property), the higher the oil resistance.

In the case where the melting point of the polyolefin as the main component is lower than 110 ℃, in the oil resistance test, the crystal of the polyolefin as the main component is melted and the oil is easily diffused in the first insulating layer. As a result, the oil resistant tensile property change rate becomes large.

The degree of crystallinity of the polyolefin as the main component is preferably high. In the case where the degree of crystallization of the polyolefin as the main component is high, the oil resistance of the first insulating layer is higher. As a method for increasing the degree of crystallization of the polyolefin as the main component, there is a method of using a crystalline polyolefin having a melting point of 110 ℃ or higher (preferably 120 ℃ or higher) as the polyolefin as the main component. Examples of the crystalline polyolefin having a melting point of 110 ℃ or higher include 1 or a combination of 2 or more of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polypropylene. Among them, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene are preferable because they are less likely to disintegrate when the first insulating layer is crosslinked by electron beam irradiation or the like.

The first polymer comprises an acid-modified polyolefin. The acid-modified polyolefin may or may not be a main component polyolefin. By the first polymer containing the acid-modified polyolefin, the electrical characteristics of the first insulating layer are improved.

Examples of the polyolefin in the acid-modified polyolefin include 1 or more selected from the group consisting of polyethylene, ethylene- α -olefin, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and vinyl acetate copolymer.

The first polymer preferably contains a rubber component. When the first polymer contains a rubber component, the inorganic filler has good compatibility. Examples of the rubber component include ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (hnbr), acrylic rubber, ethylene-acrylate 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 having a polystyrene block, and urethane rubber.

In the rubber component, EOR and EBR have no double bond. Therefore, in the case where the first polymer contains EOR and EBR, the risk of scorching during extrusion can be reduced. In addition, EOR and EBR have no polarity. Therefore, when the first polymer contains EOR or EBR, the electrical characteristics of the first insulating layer can be improved.

The first insulating layer may or may not contain an inorganic filler. When the first insulating layer contains an inorganic filler, the amount of the inorganic filler incorporated in the first insulating layer is 150 parts by mass or less per 100 parts by mass of the first polymer. When the amount of the inorganic filler added is 150 parts by mass or less, the elongation at break of the first insulating layer is less likely to decrease. The amount of the inorganic filler blended is preferably 100 parts by mass or less, and more preferably 80 parts by mass or less, with respect to 100 parts by mass of the first polymer.

When the first insulating layer contains the inorganic filler, the amount of organic substances contained in the first insulating layer can be reduced. If the amount of organic matter is reduced, toxic gas generated when the first insulating layer is burned can be reduced. Examples of the toxic gas include carbon monoxide and carbon dioxide. The amount of the inorganic filler in the first insulating layer is preferably 20 parts by mass or more, and more preferably 40 parts by mass or more, per 100 parts by mass of the first polymer component.

Examples of the inorganic filler include silicates such as kaolinite, kaolin, calcined clay, talc, mica, wollastonite, and pyrophyllite, oxides such as silica, alumina, zinc oxide, titanium oxide, calcium oxide, and magnesium oxide, carbonates such as calcium carbonate, zinc carbonate, and barium carbonate, and hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.

Since the amount of the inorganic filler blended in the first insulating layer is 150 parts by mass or less with respect to 100 parts by mass of the first polymer, the electrical insulating property of the first insulating layer is high even when a part or the whole of the inorganic filler is a metal hydroxide.

The inorganic filler may be composed of only 1 type, or may be a mixture of 2 or more types. When the first insulating layer contains hydrophobic calcined clay or talc, the electrical characteristics of the first insulating layer are improved. Calcined clay, talc, contains no carbon. Therefore, when the first insulating layer contains calcined clay or talc, the amount of carbon monoxide generated during combustion of the first insulating layer can be reduced.

The inorganic filler is preferably subjected to a surface treatment such as silane treatment. When the inorganic filler is subjected to a surface treatment such as a silane treatment, the adhesion between the inorganic filler and the first polymer is improved. As a result, the insulating performance of the first insulating layer is further improved.

The heat of fusion of the first insulating layer is preferably 65J/g or more. When the heat of fusion of the first insulating layer is 65J/g or more, the oil resistance of the first insulating layer is further improved.

The first insulating layer is preferably crosslinked. In the case where the first insulating layer is crosslinked, oil resistance is improved. The crosslinking method is not particularly limited. Examples of the crosslinking method include chemical crosslinking, irradiation crosslinking, and crosslinking by other chemical reactions. For the chemical crosslinking, for example, organic peroxides, sulfur compounds, silanes, and the like are used. For the irradiation crosslinking, for example, electron beams, radiation, or the like are used.

The first insulating layer may also contain a crosslinking aid, a flame retardant aid, an ultraviolet absorber, a light stabilizer, a softener, a lubricant, a colorant, a reinforcing agent, a surfactant, a plasticizer, a metal chelating agent, a foaming agent, a compatibilizer, a processing aid, a stabilizer, and the like, as necessary.

(1-3) second insulating layer

The second insulating layer is located on the outer peripheral side of the first insulating layer. For example, the second insulating layer is in contact with the first insulating layer. In addition, another layer may be interposed between the second insulating layer and the first insulating layer.

The second insulating layer includes a halogen-free flame-retardant resin composition. The second insulating layer contains a flame retardant. As the flame retardant, a halogen-free flame retardant is preferable. The halogen-free flame retardant does not generate halogen gas when burning. As the halogen-free flame retardant, a metal hydroxide is preferable. Examples of the metal hydroxide include magnesium hydroxide and aluminum hydroxide.

The halogen-free flame retardant is preferably a substance that hardly generates phosphine gas or cyanide gas harmful to the human body. Examples of the halogen-free flame retardant which easily generates a phosphine gas and a cyanide gas include a phosphorus flame retardant such as red phosphorus, and a triazine flame retardant such as melamine cyanurate.

Examples of the halogen-free flame retardant include clay, silica, zinc stannate, zinc borate, calcium borate, dolomite hydroxide, and silicone.

The flame retardant may be surface-treated in consideration of dispersibility of the flame retardant and the like. Examples of the substance used for the surface treatment include a silane coupling agent, a titanate coupling agent, and a fatty acid. Examples of the fatty acid include stearic acid.

The amount of the flame retardant to be blended is not particularly limited. The amount of the flame retardant to be blended is preferably 150 parts by mass or more and 300 parts by mass or less, and more preferably 150 parts by mass or more and 250 parts by mass or less, with respect to 100 parts by mass of the second polymer. When the amount of the flame retardant is 150 to 300 parts by mass based on 100 parts by mass of the second polymer, the flame retardancy of the second insulating layer is further improved.

When a metal hydroxide is contained as the flame retardant, the amount of the metal hydroxide is preferably 150 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the second polymer. When the amount of the metal hydroxide is 150 to 300 parts by mass with respect to 100 parts by mass of the second polymer, the flame retardancy of the second insulating layer is further improved.

The second insulating layer contains a second polymer. The second polymer contains, for example, a polyolefin. The second polymer preferably comprises an ethylene vinyl acetate copolymer as a main component. The main component of the second polymer means a component contained in the second polymer in the largest amount among polymer components.

Ethylene vinyl acetate copolymers are preferred because they undergo endothermic reactions upon combustion due to deacetylation of acetic acid. The second polymer may contain only 1 ethylene vinyl acetate copolymer or may contain a mixture of ethylene vinyl acetate copolymers.

The polyolefin other than the ethylene-vinyl acetate copolymer includes, for example, acid-modified ethylene- α -olefin, and when the second polymer includes acid-modified ethylene- α -olefin, the low temperature property of the second insulating layer is improved.

The second insulating layer is preferably crosslinked. In the case where the second insulating layer is crosslinked, dripping during combustion can be suppressed. The crosslinking method is not particularly limited. Examples of the crosslinking method include chemical crosslinking, irradiation crosslinking, and crosslinking by other chemical reactions. For the chemical crosslinking, for example, organic peroxides, sulfur compounds, silanes, and the like are used. For the irradiation crosslinking, for example, electron beams, radiation, or the like are used.

The second insulating layer may contain a crosslinking agent, a crosslinking aid, a flame retardant aid, an ultraviolet absorber, a light stabilizer, a softening agent, a lubricant, a colorant, a reinforcing agent, a surfactant, an inorganic filler, an oxidation inhibitor, a plasticizer, a metal chelating agent, a foaming agent, a compatibilizer, a processing aid, a stabilizer, and the like, as necessary.

The insulated wire of the present disclosure has, for example, the configuration shown in fig. 1. The insulated wire 1 includes a conductor 3, a first insulating layer 5, and a second insulating layer 7. The first insulating layer 5 covers the conductor 3. The second insulating layer 7 is located on the outer peripheral side of the first insulating layer 5. In the embodiment shown in fig. 1, the second insulating layer 7 is in contact with the first insulating layer 5.

2. Composition of insulated cable

The insulated cable of the present disclosure has, for example, the configuration shown in fig. 2. The insulated cable 9 includes at least 1 insulated wire 1 and a sheath 11. In the embodiment shown in fig. 2, the insulated cable 9 includes 2 insulated wires 1. The insulated electric wire 1 is accommodated inside the sheath. As a material of the sheath, for example, the same material as that of the second insulating layer 7 can be used.

3. Examples of the embodiments

(3-1) production of insulated wire

Insulated wires of examples 1 to 7 and comparative examples 1 to 3 were produced as follows. The raw materials shown in the row of "first insulating layer" in table 1 or 2 were kneaded with 14-inch open rolls so as to have respective mixing ratios, and granulated, thereby producing a material for the first insulating layer. The raw materials shown in the row of "second insulating layer" in table 1 or 2 were kneaded with 14-inch open rolls so as to have a suitable mixing ratio, and granulated to produce a material for the second insulating layer.

[ Table 1]

[ Table 2]

The unit of the amount blended in tables 1 and 2 is part by mass. EVA "in tables 1 and 2¹⁾"is EV270 from DuPont chemical of Mitsui. "EVA¹⁾"is an ethylene vinyl acetate copolymer. EVA "in tables 1 and 2²⁾"is V9000 manufactured by DuPont chemical of Mitsui. "EVA²⁾"is an ethylene vinyl acetate copolymer.

"modified polyolefin" in tables 1 and 2³⁾"TAFMER MH7020 manufactured by Mitsui Chemicals. "modified polyolefin³⁾"is prepared by modifying ethylene- α -olefin copolymer with maleic anhydrideThe resulting acid-modified polyolefin. Magnesium hydroxide in tables 1 and 2⁴⁾"is MAGSEEDS S3 manufactured by Shendao chemical industry. "magnesium hydroxide⁴⁾"corresponds to metal hydroxides and halogen-free flame retardants.

"PE" in tables 1 and 2⁵⁾"is SP4030 made of Priman polymer. "PE⁵⁾"is polyethylene. "PE⁵⁾"has a melting point of 127 ℃. "PE" in tables 1 and 2⁶⁾"is SP1510 made of Priman Polymer. "PE⁶⁾"is polyethylene. "PE⁶⁾"has a melting point of 117 ℃.

"EBR" in tables 1 and 2⁷⁾"TAFMER DF840, manufactured by Mitsui Chemicals. "EBR⁷⁾"is an ethylene-butene-1 copolymer rubber. "EBR⁷⁾"corresponds to the rubber component. "EBR⁷⁾"has a melting point of 66 ℃. "modified polyolefin" in tables 1 and 2⁸⁾"is Bondine LX4110 manufactured by Akema. "modified polyolefin⁸⁾"is an acid-modified polyolefin obtained by modifying an ethylene-ethyl acrylate copolymer with maleic anhydride. "modified polyolefin⁸⁾"melting point is 107 ℃.

"inorganic Filler" in tables 1 and 2⁹⁾"TRANSLINK 37 by BASF. Inorganic filler⁹⁾"is calcined clay. "inorganic Filler" in tables 1 and 2¹⁰⁾"is MICROACE L1 made by Nippon talc. Inorganic filler¹⁰⁾"is calcined clay. "PE" in tables 1 and 2¹¹⁾"Novatec ZF33 made of Japanese polyethylene. "PE¹¹⁾"is polyethylene. "PE¹¹⁾"melting point is 107 ℃.

In Table 1, "PE⁵⁾”、“PE⁶⁾”、“EBR⁷⁾"," modified polyolefin⁸⁾'and' modified polyolefin³⁾"corresponds to the first polymer. Examples 1, 3 and 6 in which "PE⁵⁾"corresponds to the major constituent polyolefin. In examples 2 and 7, "PE⁶⁾"corresponds to the major constituent polyolefin. In Table 1, "EVA¹⁾"and" EVA²⁾"corresponds to the second polymer.

The "others" in tables 1 and 2 are substances obtained by mixing the respective components in the mixing ratios shown in table 3.

[ Table 3]

Next, 2-layer extrusion was performed using a 40mm extruder, and the conductor was coated to obtain an insulated wire. The insulated wire is provided with the first insulating layer made of the material of the first insulating layer as described above and the second insulating layer made of the material of the second insulating layer as described above. The conductors were tin plated conductors configured as 37 conductors/0.18 mm. The insulated electric wire thus manufactured had the structure shown in fig. 1. Next, the first insulating layer and the second insulating layer were crosslinked by irradiation with electron rays of 5 Mrad.

(3-2) evaluation of insulated electric wire

The insulated wires of the respective examples and the respective comparative examples were evaluated as follows.

(i) Evaluation of tensile Strength and elongation at Break

A tensile test was performed at a displacement speed of 250mm/min on the test body, and tensile strength and elongation at break were measured.A determination was made as to the elongation at break.A determination result was "○" if the elongation at break was 150% or more, and the other cases were "X".

(ii) Evaluation of oil-resistant tensile Strength and oil-resistant elongation Change Rate

After the evaluation of the above (i), the test bodies were immersed in IRM902 heated to 100 ℃ for 72 hours. The test bodies were then left at room temperature for about 16 hours. Then, the tensile strength and the elongation at break of the test piece were measured in the same manner as in (i) above. The tensile strength measured at this time was taken as the tensile strength after soaking. The elongation at break measured at this time was defined as the elongation at break after soaking.

The rate of change in tensile strength after soaking with respect to the tensile strength measured in the above (i) (hereinafter referred to as the oil-resistant tensile strength rate of change) was calculated. Further, the change rate of elongation at break after soaking with respect to the elongation at break measured in the above (i) (hereinafter referred to as the oil-resistant elongation at break change rate) was calculated.

The oil resistance tensile strength change rate and the oil resistance elongation at break change rate were determined, and if the absolute value of the oil resistance tensile strength change rate was 30% or less, the determination result on the oil resistance tensile strength change rate was "○", and the other cases were "x".

In addition, if the absolute value of the change rate of the oil resistance elongation at break is 40% or less, the determination result on the change rate of the oil resistance elongation at break is "○", and the other cases are "x".

(iii) Flame retardancy test

Flame retardancy tests were carried out according to EN 45545-2. The specific method is as follows. The flame of the burner was brought into contact with the vertically supported insulated wire for 1 minute, and then the flame was extinguished. Next, the distance between the upper fixing part and the upper end of the carbonizing part was measured. Further, the distance between the upper fixing portion and the lower end of the carbonized part was measured.

The result of the flame retardancy test is "○" if the distance between the upper fixing section and the upper end of the carbonized part is 50mm or more and the distance between the upper fixing section and the lower end of the carbonized part is less than 540 mm.

For the insulated wires whose determination result of the above test was not "○", the horizontal flame retardancy test was carried out in accordance with jis c3005, and when the self-extinguishment was within 15 seconds, the determination result of the flame retardancy test was "△", and when the self-extinguishment was not within 15 seconds, the determination result of the flame retardancy test was "x".

(iv) Determination of the Heat of fusion

The first insulating layer was cut from the insulated wire as a test body. The measurement is carried out at 0 ℃ to 160 ℃ using a Differential Scanning Calorimetry (DSC) method. The temperature rise rate was set at 10 ℃/min, and the heat of fusion in the range of 50 ℃ to 140 ℃ was determined.

(v) Comprehensive evaluation

When all of the determination results on the elongation at break, the determination results on the change rate in the oil-resistant tensile strength, the determination results on the change rate in the oil-resistant elongation at break, and the determination results on the flame retardancy test were "○", the result of the comprehensive evaluation was "◎".

In examples 1 to 7, the overall evaluation result was "◎" or "○", whereas in comparative examples 1 to 3, the overall evaluation result was "x".

4. Other embodiments

The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments and can be implemented by being modified in various ways.

(1) The functions of 1 component in each of the above embodiments may be shared by a plurality of components or the functions of a plurality of components may be exhibited by 1 component. Further, a part of the configuration of each of the above embodiments may be omitted. Further, at least a part of the structure of each of the above embodiments may be added to, replaced with, or the like the structure of the other above embodiments. All the aspects included in the technical idea defined by the terms described in the claims are embodiments of the present disclosure.

(2) The present disclosure can be realized in various forms other than the insulated wire described above, such as a system using the insulated wire as a component, a method for manufacturing an insulated wire, and a method for manufacturing an insulated cable.

Claims

1. An insulated wire comprising a conductor, a first insulating layer covering the conductor, and a second insulating layer located on the outer peripheral side of the first insulating layer,

the first insulating layer contains a first polymer and 150 parts by mass or less of an inorganic filler per 100 parts by mass of the first polymer,

the second insulating layer contains a halogen-free flame-retardant resin composition containing a second polymer mainly composed of an ethylene-vinyl acetate copolymer and a metal hydroxide which is contained in an amount of 150 to 250 parts by mass per 100 parts by mass of the second polymer,

the first polymer contains a polyolefin having a melting point of 110 ℃ or higher and an acid-modified polyolefin as main components of the first polymer,

the first insulating layer and the second insulating layer are crosslinked.

2. The insulated electric wire according to claim 1, wherein the heat of fusion of the first insulating layer is 65J/g or more.

3. The insulated wire according to claim 1 or 2, wherein the polyolefin in the acid-modified polyolefin contains 1 or more selected from the group consisting of polyethylene, ethylene- α -olefin, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and vinyl acetate copolymer.

4. The insulated wire according to any one of claims 1 to 3, wherein the inorganic filler contains 1 or more of clay and talc.