JP2022044095A - Insulated wire and cable - Google Patents

Abstract

To provide an insulated wire obtained using a non-halogen polymer composition excellent in heat resistance and mechanical characteristics.SOLUTION: An insulated wire is provided, having a conductor 1, an inner layer 3a covering the conductor, and an outer layer 3b covering the inner layer, the inner layer is comprised of a first non-halogen polymer composition including a first base polymer, the outer layer is comprised of a second non-halogen polymer composition including a second base polymer and a metal hydroxide, the first base polymer is comprised of silicone rubber and the second base polymer is comprised of polyolefin. The outer layer has a tearing strength of 35 kN/m or more in a tearing test using an uncut angle test piece defined in JIS K 6252.SELECTED DRAWING: Figure 1

Description

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

Insulated electric wires and cables used in railway vehicles, automobiles, electrical and electronic equipment, etc. are made of polyvinyl chloride admixture and polychloroprene rubber admixture, which are well-balanced in oil resistance / fuel resistance, low temperature characteristics, and flame retardancy. Materials, chlorosulfonated polyethylene admixtures, chlorinated polyethylene admixtures, fluororubbers, fluororesins, polyethylene and other polyolefin resins have been used with halogen-based flame retardant added in order to improve flame retardancy. However, these halogen-containing materials generate a large amount of toxic and harmful gases during combustion, and generate highly toxic dioxin depending on the combustion conditions. For this reason, insulated electric wires and cables using halogen-free halogen-free materials as coating materials have begun to spread from the viewpoint of safety in the event of a fire and reduction of environmental load.

Further, a fluororubber admixture or fluororesin having excellent heat resistance and aging resistance is often used as a covering material for an insulated wire or cable in which a large current is passed and the conductor becomes hot. These fluorine-based materials contain halogens as described above. For this reason, silicone rubber, which has excellent heat resistance and aging resistance, is often used as the covering material for halogen-free insulated wires and cables, next to fluorine-based materials.

Silicone rubber is difficult because the base rubber itself is flame retardant, so it is not necessary to mix a large amount of flame retardant to achieve the high flame retardancy required for insulated wires and cables used in railway vehicles, for example. It can be said that it is a material with excellent electrical insulation even if it is flammable.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2001-35267), a silicone polymer composition in which fine powder of mica is blended on a conductor is coated as a refractory layer, and an insulator is extruded on the refractory layer. A refractory electric wire characterized by being covered is disclosed.

Japanese Unexamined Patent Publication No. 2001-35267

As described above, silicone rubber is a material that is flame-retardant and has excellent electrical insulation, but is known to be inferior in mechanical properties to other resins and rubbers. It is known that the tear strength is particularly low, and when using an insulated wire or cable coated with silicone rubber, the coating tears as soon as it is damaged, making it difficult to use in places that are susceptible to damage. There was a drawback such as.

Therefore, according to the Japanese Industrial Standards, when the tear strength of the silicone rubber to be coated is 25 kN / m or less in the electric wire using the silicone rubber, a reinforcing layer of glass fiber braid is provided on the outside of the coating layer made of the silicone rubber. (Eg C3323, C3315).

In addition, EN50264-3-1 (small diameter crosslinked elastomer insulated single-core cable) and EN50382-2 (120 ° C / 150 ° C rated silicone rubber insulated single-core cable), which are the European regional standards for railway vehicle electric wires, have the same rating. Even if the voltage is high, the thickness of EN50382-2 using silicone rubber is set to be thicker than that of EN50264-3-1 in the insulating layer of the insulated wire and the sheath layer of the cable. The mechanical properties (tear strength) are guaranteed.

However, if a glass fiber braid is provided as a reinforcing layer as specified by the Japanese Industrial Standards, it is necessary to process the glass fiber braid when processing the terminal of the insulated wire, which complicates the terminal processing and also makes the glass fiber braid. The short fibers of glass generated when cutting the glass may be mixed and caught in the connection part, and the insulation resistance of the connection part may increase, causing abnormal heat generation. Further, even if the coating layer made of silicone rubber is thickened, cracks will develop regardless of the thickness of the coating if it is damaged by trauma, so it cannot be said to be an essential solution. In particular, some insulated wires and cables for railway vehicles are used in moving parts outside the vehicle (for example, jumper wires), and are required to have trauma resistance.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulated electric wire and a cable having excellent heat resistance and mechanical properties.

The insulated wire of 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, and the first insulating wire. The layer comprises a first non-halogen polymer composition comprising a first base polymer, and the second insulating layer comprises a second non-halogen polymer composition comprising a second base polymer and a metal hydroxide, said first base. The polymer is made of silicone rubber, the second base polymer is made of polyolefin, and the second insulating layer has a tear strength of 35 kN in a tear test using a non-cut angle type test piece specified in JIS K 6252. / M or more.

The cable according to one aspect of the present invention is a cable having a conductor, an insulating layer covering the conductor, and a sheath layer covering the insulating layer, wherein the insulating layer contains a first base polymer. The sheath layer is made of a second non-halogen polymer composition containing one non-halogen polymer composition, the first base polymer is made of a silicone rubber, and the second base is made of a second base polymer and a metal hydroxide. The polymer is made of polyolefin, and the sheath layer has a tear strength of 35 kN / m or more in a tear test using a non-cut angle type test piece specified in JIS K 6252.

According to the insulated wire or cable of the present invention, heat resistance and mechanical properties can be improved.

It is sectional drawing which shows the structural example of the insulated wire of Embodiment 1. FIG. It is sectional drawing which shows the structural example of the cable of Embodiment 2. It is sectional drawing which shows the other structural example of the cable of Embodiment 2. FIG. It is sectional drawing which shows the structure of the cable of an Example and a comparative example. It is a graph which shows the Arrhenius plot.

(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 10 shown in FIG. 1 has a conductor 1 and an insulating layer 3. The insulating layer 3 has an inner layer (inner insulating layer) 3a and an outer layer (outer insulating layer) 3b.

As the conductor 1, 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 1, a plurality of metal wires may be used, or stranded wires may be used.

[Inner layer]
As the inner layer 3a, a polymer composition containing a base polymer, a cross-linking agent, and other additives can be used. This polymer composition is a halogen-free non-halogen polymer composition.

(Base polymer)
Silicone rubber is used as the base polymer of the inner layer. The base rubber itself of this silicone rubber is flame-retardant. Therefore, it can be said that the base polymer of the polymer composition for the inner layer is a non-halogen flame-retardant silicone rubber. This polymer composition for the inner layer may be referred to as a silicone rubber composition. As such a silicone rubber, a silicone rubber used for ordinary electric wire coating can be used. In particular, in order to improve flame retardancy and mechanical properties, it is preferable to use one to which fumed silica or precipitated silica is added. Further, as an index of mechanical properties, it is preferable to use one having a tear strength of 25 kN / m or more in a tear test using an angle type test piece without a notch specified in JIS K6252. Preferred silicone rubbers used as the base polymer include, for example, SE1607U manufactured by Toray Dow Corning.

(Crosslink)
Silicone rubber needs to be crosslinked for the purpose of deformation due to heating and improvement of mechanical properties. As the cross-linking agent and the cross-linking method, those applied to ordinary silicone rubber can be used. Although not particularly limited, the hydrosilylation reaction using an organic peroxide or platinum catalyst that can be crosslinked with hot air or saturated steam immediately after the silicone rubber is extruded onto the conductor in the insulated wire. It is preferable to carry out cross-linking with.

(Other additives)
If necessary, a colorant, a stabilizer, or the like can be added to the polymer composition for the inner layer.

[Outer layer]
As the outer layer 3b, a polymer composition containing a base polymer, a flame retardant, and other additives can be used. This polymer composition is a halogen-free non-halogen polymer composition.

(Base polymer)
Polyolefin is used as the base polymer of the outer layer. This polymer composition for the outer layer may be referred to as a polyolefin composition. Polyolefins have better mechanical properties than the silicone rubber used for the inner layer. The term polyolefin here refers to low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, random polypropylene, natural rubber, butyl rubber, ethylene-propylene copolymer, and ethylene-propylene, which do not contain halogen in their molecular structure. -Diene copolymer, ethylene-α olefin copolymer, styrene-butadiene rubber, hydrogenated styrene butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester An acid-modified polymer in which maleic acid, maleic anhydride, fumaric acid, carboxylic acid, or the like is introduced into the polymer and the above-mentioned polymer at the polymer terminal, or grafted or copolymerized thereof is shown. These polymers can be used alone or in a blend of two or more.

In order to obtain high heat aging resistance, it is preferable to select a polymer that does not contain a double bond in the polymer main chain. Ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, etc. are required to have mechanical properties, low temperature resistance, oil resistance, etc. It is preferable to use an ethylene-α-olefin copolymer and an acid-modified polymer thereof.

(Flame retardants)
A metal hydroxide is used as the flame retardant. Further, as the metal hydroxide, magnesium hydroxide and aluminum hydroxide, which are metal hydroxides whose dehydration heat absorption reaction is close to the decomposition temperature of the polymer, are preferable. These metal hydroxides may be surface-treated with higher fatty acids, silane coupling agents, and titanate-based coupling agents in order to improve dispersibility, interaction with resins, and mechanical properties. It is preferable to use one surface-treated with a silane coupling agent having an acrylic group, a methacrylic group and a vinyl group.

The amount of the metal hydroxide added can be appropriately changed according to the flame retardancy required for the insulated wire, but is advanced so as to pass the vertical tray flame retardancy test specified in, for example, IEEE1202 and IEC60332. When flame retardancy is required, the range is preferably 130 parts by mass or more and 180 parts by mass or less with respect to 100 parts by mass of the base polymer. When the addition amount is 130 parts by mass or more, the flame retardancy can be improved, and when the addition amount is 180 parts by mass or less, deterioration of mechanical properties and low temperature can be suppressed.

As the flame retardant, a halogen-free flame retardant can be added as needed in addition to the metal hydroxide. Examples of such flame retardants include red phosphorus and phosphoric acid ester derivatives, phosphorus flame retardants typified by intomescent flame retardants, nitrogen flame retardants typified by melamine / cyanurate derivative mixtures, catechols, and erosators. Polyvalent phenol compounds such as acid derivatives, silicone flame retardants and the like can be used.

(Crosslink)
Polyolefins, like silicone rubber, need to be crosslinked for the purpose of deformation due to heating and improvement of mechanical properties. The cross-linking agent and the cross-linking method are not particularly limited, but peroxide cross-linking using an organic peroxide cross-linking agent, radiation cross-linking using ionizing radiation, a silane coupling agent grafted on a base polymer with an organic peroxide, and water. Silane hydroxide cross-linking, which is cross-linked by heat, is preferable. In particular, it is more preferable to perform peroxide cross-linking and radiation cross-linking.

(Other additives)
Other additives are added to the polymer composition for the outer layer as needed. Other additives include antioxidants, metal chelating agents (metal damage inhibitors), lubricants, flame retardant aids, cross-linking aids, cross-linking accelerators, surfactants, compatibilizers, UV absorbers, hindered amines. Examples include light stabilizers (HALS). In order to obtain particularly high heat aging resistance, it is preferable to add 5 parts by mass or more of an antioxidant, preferably a phenol-based antioxidant and a sulfur-based antioxidant with respect to 100 parts by mass of the base resin. Further, a metal chelating agent, preferably bis dodecane diate [N2- (2-hydroxybenzoyl) hydrazide] (for example, CDA-6 manufactured by ADEKA) and / and bis isophthalate (2-phenoxypropionyl hydrazide) (for example, manufactured by Mitsui Kagaku Fine). It is preferable to add 1 part by mass or more of Cunox AX) with respect to 100 parts by mass of the base resin.

The polymer composition for the outer layer is provided to supplement the mechanical properties of the insulated wire, especially the tear strength. In terms of molecular structure, polyolefin, which is a pace polymer for the outer layer, has a higher tear strength than silicone rubber, which is a pace polymer for the inner layer, but tear strength is increased by adding a filler (flame retardant) such as metal hydroxide. Will decrease. As described above, there is a standard that the coating layer made of silicone rubber has a tear strength of 25 kN / m or more and does not require glass fiber braiding, but the insulated wire of the present embodiment has sufficient tear resistance against trauma. Considering the property, it is preferable that the outer layer has a tear strength of 35 kN / m or more.

As described above, in the present embodiment, by forming the insulating layer of the insulated wire with the above-mentioned inner layer and outer layer, the silicone rubber composition of the inner layer can maintain high heat aging resistance, and the polyolefin composition of the outer layer can be maintained. It is possible to improve mechanical properties including tear resistance of an object.

Further, regarding the thickness of the inner layer and the outer layer, it is more preferable that the inner layer is thicker than the outer layer. By making the inner layer thicker, the heat aging resistance can be further improved.

In general, in an insulated wire having two insulating layers, the inner layer is often provided with electrical insulation, and the outer layer is provided with functions such as flame retardancy, oil resistance, and mechanical properties, and the characteristics are often shared. .. In this case, if the layer for ensuring the electrical insulation is made thicker than necessary, the flame retardancy is particularly hindered. Therefore, the outer layer is made thicker than the inner layer for ensuring the electrical insulation.

Further, there is a refractory electric wire having a refractory layer as an inner layer which is cured by combustion and retains insulation even after combustion, and silicone rubber may be used for the refractory layer. However, since a large amount of filler such as mica is added to the silicone rubber in this refractory layer, the mechanical properties and insulating properties are poor, and the refractory layer which is the inner layer must be thinner than the outer layer above it. I don't get it. In other words, in order to ensure the mechanical properties and insulation of the inner layer, the outer layer must be thickened.

On the other hand, in the inner layer of the present embodiment, it is not assumed that mica is used, and the heat aging resistance cannot be lowered by the mica. For example, in the inner layer of the refractory electric wire, EN50382-1 While the EI 111 specified in the above can not be satisfied, the inner layer of the present embodiment satisfies the EI 111 specified in EN 50382-1.

EN50382-1 is Railway applications-Railway rolling stock high temperature power cables having special fire performance -Part1: General requirements.

Further, in the present embodiment, although silicone rubber having flame retardancy and excellent electrical insulation is used for the inner layer, it is not necessary to thin them in consideration of flame retardancy and electrical insulation. On the other hand, the outer layer does not need to be thick as long as it can maintain mechanical properties, especially to suppress tearing due to trauma. Therefore, by using silicone rubber in the inner layer where the temperature rises due to the heat from the conductor and making it thicker than the outer layer, the heat aging resistance can be further improved.

Insulated electric wires using silicone rubber are used when a rated temperature of 120 ° C. or higher requires high heat resistance and aging resistance. When the insulated wire of the present embodiment is used at a rated temperature of 120 ° C. or higher, a long-term aging test specified in EN50305, specifically, 20000 hours at 140 ° C., even in the outer layer where heat is not directly transferred from the conductor. Must retain 50% elongation at break after heat aging test.

Further, in order to maintain 50% fracture elongation after a heat aging test at 140 ° C. for 20000 hours in an outer layer made of a polymer composition containing a metal hydroxide as a flame retardant, the progress of oxidative deterioration due to metal damage is particularly promoted. It needs to be suppressed. Metal hydroxides contain a small amount of metal compounds that easily cause metal damage. The concentration of an undesired metal compound that causes metal damage may change depending on the amount of metal hydroxide added, but the Fe content in the polymer composition for the outer layer is 200 ppm or less and the Cu content is elemental. If the concentration is 100 ppm or less, metal damage can be suppressed.

As described above, in the insulated wire of the present embodiment, since the silicone rubber composition is used as the inner layer of the insulating layer on the outer periphery of the conductor and the polyolefin composition is used as the outer layer, heat resistance (including heat aging resistance) is used. ) And mechanical properties can be improved.

(Embodiment 2)
In the present embodiment, the material of the inner layer of the first embodiment is used as the insulating layer of the insulated wire, and the material of the outer layer of the first embodiment is used as the sheath layer of the cable having the insulated wire.

FIG. 2 is a cross-sectional view showing a configuration example of the cable of the present embodiment. The cable 20 shown in FIG. 2 has an insulated wire 10 and a sheath layer 4 provided on the outside of the insulated wire 10. The insulated wire 10 has a conductor 1 and an insulating layer 3, and the silicone rubber composition used as the material of the inner layer (3a) of the first embodiment is used as the insulating layer 3. Further, as the sheath layer 4, the above-mentioned polyolefin composition which is the material of the outer layer (3b) of the first embodiment is used. The number of insulated wires 10 in the cable 20 may be two or more. FIG. 3 is a cross-sectional view showing another configuration example of the cable of the present embodiment.

The cable 20 shown in FIG. 3 has a twisted electric wire formed by twisting three insulated electric wires 10 and a sheath layer 4 formed by extruding and coating a polymer composition for an outer layer on the outer periphery of the twisted electric wire. I have. The insulating layer 3 of the insulated wire 10 is formed by extruding and coating a polymer composition for an inner layer. Here, a presser foot tape 5 such as PET (polyethylene terephthalate) tape is twisted and wound around the outer periphery of the electric wire, a shield layer 6 made of a metal braid or the like is provided on the outer periphery thereof, and a sheath layer 4 is provided on the outer periphery of the shield layer 6. There is. The sheath layer 4 is formed by extruding and coating a polymer composition for an outer layer.

As described above, in the cable of the present embodiment, the silicone rubber composition is used as the insulating layer of the insulated wire, and the polyolefin composition is used as the sheath layer on the outer periphery of the insulated wire. Including) and mechanical properties can be improved.

[Example]
The materials used in Examples and Comparative Examples are shown in Tables 1 and 2. Specific material names are shown below each table.

Flame-retardant silicone rubber: SE-1607U (Toray Dow Corning)
Coloring master batch: KE-color-BL (Shinetsu Silicone)
Crosslinker Master Batch: RC-14A (Toray Dow Corning)

Ethylene-vinyl acetate copolymer: Evaflex EV45LX [VA amount 46%] (Mitsui Gu Polychemical)
Ethylene / α-olefin copolymer: Toughma A4050S (Mitsui Chemicals)
Maleic anhydride-modified ethylene / α-olefin copolymer: Toughma MH7020 (Mitsui Chemicals)
Magnesium Hydroxide 1: Magnesium S4 (Konoshima Chemical Co., Ltd.)
Magnesium hydroxide 2: Magnesium H10A (HUBER)
Silicone gum: KE-76S (Shinetsu Silicone)
Phenolic Antioxidant: Irganox 1010 (BASF)
Phenol-based / sulfur-based antioxidant mixture: AO-18 (ADEKA)
Metal chelating agent: CDA-6 (ADEKA)
Carbon Black: Asahi Thermal (Asahi Carbon)
Organic peroxide cross-linking agent: Perbutyl P (NOF)
(Cable making)
In the following examples, an insulating layer corresponding to the inner layer is formed around the conductor with the silicone rubber composition of the formulation shown in Table 1, and the sheath corresponding to the outer layer is formed with the polyolefin composition of the formulation shown in Table 2. Formed a layer. Further, in the comparative example, a cable having a different thickness and composition of the insulating layer and the sheath layer was produced.

First, the materials were weighed according to the compounding ratios shown in Table 1 and kneaded with a 12-inch open roll at room temperature to obtain a compound having a width of 120 mm and a thickness of 10 mm.

Further, the materials (other than the cross-linking agent) were weighed at the blending ratios shown in Table 2, kneaded with a 75 L pressure kneader, extruded with a strand, cooled, and pelletized. The obtained predetermined amount of pellets and the liquid cross-linking agent heated to 40 ° C. were stirred with a blender to obtain pellets impregnated with the cross-linking agent.

(Example 1)
Silicone rubber shown in Table 1 is made by wrapping a film tape 2 made of polyethylene terephthalate around a conductor (outer diameter 11 mm, cross-linking area 70 mm ² ) 1 in which a plurality of tin-plated conductors are twisted together to prevent the polymer composition from getting stuck. The composition was extruded and coated to a thickness of 1.8 mm, and immediately after that, the composition was crosslinked by heating with a hot air crosslinking device having a peak set to 300 ° C. for 10 minutes to form an insulating layer 3. As a result, the insulated wire 10 was manufactured.

The polyolefin composition of Formulation A shown in Table 2 was extruded and coated on a single-core insulated wire 10 to a thickness of 1.8 mm, and immediately after that, the polyolefin composition was crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes. The sheath layer 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 18.5 mm. This cable 20 is used as the cable of the first embodiment, and its configuration is shown in FIG. 4 (A).

(Example 2)
In the same manner as in the case of the first embodiment, the film tape 2 is wound around the conductor 1 in which a plurality of tin-plated conductors are twisted, and the silicone rubber composition shown in Table 1 is extruded and coated with a thickness of 1.8 mm. Immediately after that, the insulating layer 3 was formed by coating and cross-linking. As a result, the insulated wire 10 was manufactured.

The polyolefin composition of Formulation A shown in Table 2 was extruded and coated on a single-core insulated wire 10 to a thickness of 1.0 mm, and immediately after that, the polyolefin composition was crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes. The sheath layer 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 17 mm. This cable 20 is used as the cable of the second embodiment, and its configuration is shown in FIG. 4 (B).

(Example 3)
In the same manner as in the case of the first embodiment, the film tape 2 is wound around the conductor 1 in which a plurality of tin-plated conductors are twisted, and the silicone rubber composition shown in Table 1 is extruded and coated with a thickness of 1.8 mm. Immediately after that, the insulating layer 3 was formed by coating and cross-linking. As a result, the insulated wire 10 was manufactured.

The polyolefin composition of Formulation B shown in Table 2 was extruded and coated on a single-core insulated wire 10 to a thickness of 1.0 mm, and immediately after that, the polyolefin composition was crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes. The sheath layer 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 17 mm. This cable 20 is used as the cable of the third embodiment, and its configuration is shown in FIG. 4 (C).

(Comparative Example 1)
In Comparative Example 1, the silicone rubber compositions shown in Table 1 were used for the inner layer and the outer layer.

That is, in the same manner as in the case of the first embodiment, the film tape 2 is wound around the conductor 1 in which a plurality of tin-plated conductors are twisted, and the silicone rubber composition shown in Table 1 is formed to a thickness of 1.8 mm. The insulating layer 3 was formed by extruding and coating, and immediately after that, coating and cross-linking. As a result, the insulated wire 10 was manufactured.

The silicone rubber composition shown in Table 1 is extruded and coated on a single-core insulated wire 10 to a thickness of 1.8 mm, and immediately after that, it is crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes to form a sheath layer. 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 18.5 mm. This cable 20 is used as the cable of Comparative Example 1, and its configuration is shown in FIG. 4 (D).

(Comparative Example 2)
In Comparative Example 2, the polyolefin composition of Formulation B shown in Table 2 was used for the inner layer and the outer layer.

That is, a film tape 2 made of polyethylene terephthalate is wrapped around a conductor (outer diameter 11 mm, cross-linking area 70 mm ² ) 1 in which a plurality of tin-plated conductors are twisted to prevent the polymer composition from being embedded, and is shown in Table 2. The polyolefin composition of Formulation B was extruded and coated to a thickness of 1.8 mm, and immediately after that, it was crosslinked by heating with a hot air crosslinking device having a peak set to 300 ° C. for 10 minutes to form an insulating layer 3. As a result, the insulated wire 10 was manufactured.

The polyolefin composition of Formulation B shown in Table 2 was extruded and coated on a single-core insulated wire 10 to a thickness of 1.0 mm, and immediately after that, the polyolefin composition was crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes. The sheath layer 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 17 mm. This cable 20 is used as the cable of Comparative Example 2, and its configuration is shown in FIG. 4 (E).

(Comparative Example 3)
In Comparative Example 3, the polyolefin composition of Formulation B shown in Table 2 was used for the inner layer, and the silicone rubber composition of Formulation B shown in Table 1 was used for the outer layer.

That is, a film tape 2 made of polyethylene terephthalate is wrapped around a conductor (outer diameter 11 mm, cross-linking area 70 mm ² ) 1 in which a plurality of tin-plated conductors are twisted to prevent the polymer composition from being embedded, and is shown in Table 2. The polyolefin composition of Formulation B was extruded and coated to a thickness of 1.8 mm, and immediately after that, it was crosslinked by heating with a hot air crosslinking device having a peak set to 300 ° C. for 10 minutes to form an insulating layer 3. As a result, the insulated wire 10 was manufactured.

The silicone rubber composition having the composition shown in Table 1 was extruded and coated on the single-core insulated wire 10 to a thickness of 1.8 mm, and immediately after that, the silicone rubber composition was crosslinked by heating with saturated steam of 1.8 MPaG for 5 minutes. The sheath layer 4 was formed. As a result, the cable 20 was manufactured. The outer diameter of this cable 20 was 18.5 mm. This cable 20 is used as the cable of Comparative Example 3, and its configuration is shown in FIG. 4 (F).

[Tear test]
The silicone rubber composition of the formulation shown in Table 1, the polyolefin composition of formulation A shown in Table 2, and the polyolefin composition of formulation B shown in Table 2 were each molded into a sheet and evaluated. Specifically, in the case of the silicone rubber compositions having the formulations shown in Table 1, the silicone rubber composition is molded into a sheet by a hot press at 120 ° C. and then heated as it is for 10 minutes to crosslink the silicone rubber composition to a thickness of 2 mm. A sheet-shaped sample was used. Further, in the case of the polyolefin composition of Formulation A or Formulation B shown in Table 2, the polyolefin composition is molded into a sheet by a hot press at 180 ° C., and the sheet is crosslinked by heating for 10 minutes as it is, and is a sheet having a thickness of 2 mm. The sample was in the shape of a sample. This sheet-shaped sample was punched into a non-notched angle type shown in JIS K 6252, torn at a speed of 500 mm / min by the method specified in JIS K 6252, and the tear strength was measured. A tear strength of 35 kN / m or more was regarded as acceptable.

[Initial tensile test]
After disassembling the cable and removing the conductor, the sheath layer and the insulating layer were separated. The inside (conductor side) of the insulating layer was ground so as to be smooth, and the thickness was adjusted to about 1 mm. The insulating layer was punched into the dumbbell shape shown in IEC60811-1-1 to prepare a sample. This sample was pulled at a speed of 250 mm / min and the tensile strength and breaking elongation were measured. A tensile strength of 8 MPa or more and a breaking elongation of 200% or more were regarded as acceptable.

[Heat-resistant aging test]
After disassembling the cable and removing the conductor, the sheath layer and the insulating layer were separated. The inside (conductor side) of the insulating layer was ground so as to be smooth, and the thickness was adjusted to about 1 mm. The insulating layer was punched into the dumbbell shape shown in IEC60811-1-1 to prepare a sample. This sample was heated at 200 ± 3 ° C. for 240 hours by the method shown in IEC60811-1-2, then pulled at a speed of 250 mm / min, and the tensile strength and elongation at break were measured. It was accepted that the tensile strength after heating was 6 MPa or more and the breaking elongation was 160% or more.

[Arrhenius plot]
After disassembling the cable of Example 3 and removing the conductor, the sheath layer and the insulating layer were separated. The sheath layer was punched into a dumbbell shape shown in IEC60811-1-1 to prepare a sample. A long-term heat-resistant aging test (aging test at each temperature) specified in Section 7.3 of EN50305 was performed on this sample, and the time (lifetime) for 50% elongation at break after the test was determined. The obtained lifetime was Arrhenius plotted and the regression line was obtained (Fig. 5).

[Cable heat resistance aging test]
After heating the cables of Examples 2 and 3 in the oven specified in IEC60811-1-2 at 180 ° C. for 480 hours, each cable was wound around a mandrel having an outer diameter of 17 mm, and cracks in the sheath layer were confirmed.

[X-ray fluorescence analysis of sheath layer]
After disassembling the cables of Examples 2 and 3 and removing the conductor, the sheath layer and the insulating layer were separated. The Fe element concentration and Cu element concentration of the sheath layer were measured with a fluorescent X-ray analyzer.

[Comprehensive evaluation]
Those who passed all of the initial tensile test, heat-resistant aging test, and tear test were judged as passing by the comprehensive judgment. The results of the comprehensive evaluation are shown in Table 3.

Table 3 shows the results of the cable heat-resistant aging test and the fluorescent X-ray analysis of the sheath layer. The Arrhenius plot is shown in FIG.

(summary)
The cables of Examples 1 to 3 passed all of the initial tensile test, the heat resistant aging test, and the tear test. It can be seen that the cables of Examples 1 to 3 show high heat aging resistance and high tear strength of the material of the sheath layer, so that the cables have high mechanical properties while having a high rated temperature.

In particular, in the cable of Example 2, although the sheath layer is thinner than the insulating layer and the outer diameter of the cable is small, all of the initial tensile test, the heat resistant aging test, and the tear test are passed. Further, also in the cable of Example 3, although the sheath layer is thinner than the insulating layer and the outer diameter of the cable is small, the heat-resistant aging property is achieved at 140 ° C. and 20000 hours from the Arrhenius plot shown in FIG. It turns out that it is a prospect. That is, it can be seen that the cable of Example 3 retains 50% elongation at break after a heat aging test at 140 ° C. for 20000 hours.

It is considered that the improvement in heat aging resistance of the cable of Example 3 is due to the fact that metal damage is unlikely to occur. That is, the sheath layer of Example 3 has a significantly lower Fe element concentration (Fe content) than the sheath layer of Example 2, has an Fe element concentration of 200 ppm or less, a Cu element concentration of 100 ppm or less, and is a metal. It is thought that harm is unlikely to occur.

Further, in the cable heat-resistant aging test accelerating and simulating the heat aging test at 140 ° C. for 20000 hours, the cable of Example 3 did not have cracks. As described above, the cable of Example 3 has a heat-resistant aging level that can be used even in the region of the 120 ° C. rated silicone rubber electric wire / cable specified in EN50382-2, and is particularly suitable for a cable using a polyolefin composition. It can be said that it is excellent.

On the other hand, in the cable of Comparative Example 1, since the silicone rubber composition is used for the sheath layer 4, the tear strength of the sheath layer 4 is low and the mechanical properties are inferior. Further, the cable of Comparative Example 2 uses a polyolefin composition for the insulating layer 3, and in the heat aging test, the cable is so brittle that it cannot be subjected to a tensile test after heating, resulting in inferior heat aging resistance. rice field. Further, since the cable of Comparative Example 3 uses a polyolefin composition for the insulating layer and a silicone rubber composition for the sheath layer, both heat aging resistance and tear strength are inferior.

(Application example)
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 railroad vehicle can be considered. That is, it can be used as a non-halogen insulated wire for railway vehicles and a non-halogen cable for railway vehicles.

In particular, in non-halogen insulated wires for railway vehicles and non-halogen cables for railway vehicles, there are jumper wires used in moving parts outside the vehicle, and since trauma resistance is required, the above insulated wires and cables are jumper wires. It is suitable to be used as.

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.

1 Conductor 2 Film tape 3 Insulation layer 3a Inner layer 3b Outer layer 4 Sheath layer 5 Presser winding tape 6 Shield layer 10 Insulated wire 20 Cable

Claims (12)

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 polymer composition containing a first base polymer.
The second insulating layer comprises a second non-halogen polymer composition containing a second base polymer and a metal hydroxide.
The first base polymer is made of silicone rubber and is made of silicone rubber.
The second base polymer is made of polyolefin and is made of polyolefin.
The second insulating layer is an insulated wire having a tear strength of 35 kN / m or more in a tear test using a non-cut angle type test piece specified in JIS K 6252. In the insulated wire according to claim 1,
The first insulating layer is an insulated wire that is thicker than the second insulating layer. In the insulated wire according to claim 1 or 2,
The second insulating layer is an insulated wire that retains 50% elongation at break after a heat aging test at 140 ° C. for 20000 hours as defined in EN50305. In the insulated wire according to any one of claims 1 to 3,
The second insulating layer is an insulated wire having an Fe content of 200 ppm or less and a Cu content of 100 ppm or less in the second non-halogen polymer composition. In the insulated wire according to any one of claims 1 to 4, the insulated wire
The first insulating layer is an insulated wire that satisfies EI111 defined in EN50382-1. In the insulated wire according to any one of claims 1 to 5,
Insulated wire used as a jumper wire for railroad vehicles. A cable having a conductor, an insulating layer covering the conductor, and a sheath layer covering the insulating layer.
The insulating layer comprises a first non-halogen polymer composition containing a first base polymer.
The sheath layer comprises a second non-halogen polymer composition containing a second base polymer and a metal hydroxide.
The first base polymer is made of silicone rubber and is made of silicone rubber.
The second base polymer is made of polyolefin and is made of polyolefin.
The sheath layer is a cable having a tear strength of 35 kN / m or more in a tear test using a non-cut angle type test piece specified in JIS K 6252. In the cable according to claim 7,
The insulating layer is a cable thicker than the sheath layer. In the cable according to claim 7 or 8.
The sheath layer is a cable that retains 50% elongation at break after a 20000 hour heat aging test at 140 ° C. as defined in EN50305. In the cable according to any one of claims 7 to 9.
The sheath layer is a cable having a Fe content of 200 ppm or less and a Cu content of 100 ppm or less in the second non-halogen polymer composition. In the cable according to any one of claims 7 to 10.
The insulating layer is a cable that satisfies EI111 as defined in EN50382-1. In the cable according to any one of claims 7 to 11.
A cable used as a jumper wire for railroad vehicles.

Images