JP2022083355A - Insulated electric wire and cable for information transmission - Google Patents

Abstract

To provide an insulated electric wire having excellent thermal resistance and dielectric tangent increase inhibitory effect.SOLUTION: An insulated electric wire 1 having a conductor 2, where an insulation layer 3 contains polyolefin and an antioxidizing agent, the content of the antioxidizing agent is 0.1 pts.mass or more and 1.0 pts.mass or less with respect to 100 pts.mass of polyolefin, the antioxidizing agent is constituted of phenolic antioxidizing agent and sulfur-based antioxidizing agent excluding sulfur-containing phenolic antioxidizing agent, the phenolic antioxidizing agent has a less-hindered phenol structure containing no sulfur or a semi-hindered phenol structure containing no sulfur, and the content rate of the sulfur-based antioxidizing agent in the antioxidizing agent is more than 50 mass% and 90 mass% or less.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to insulated wires and cables for information transmission.

With the needs for automatic driving technology and driving assist functions of automobiles, in-vehicle information wires are required to further increase the capacity and speed of information transmission. Since the transmission loss (transmission loss) has a positive correlation with the frequency of the signal and the dielectric positive contact of the insulating layer of the signal transmission cable, in order to speed up signal transmission, the dielectric positive connection of the insulating layer is reduced and the transmission loss is transmitted. It is necessary to further reduce the signal transmission in a stable manner.

In the prior art, by using an electrically insulating material containing a phenolic antioxidant that does not have a hindered phenol structure for the insulator layer, the dielectric loss of the insulator layer in the high frequency band is small, and in a high temperature environment. A communication cable having a long life even when used is disclosed (see JP-A-2009-81132).

Japanese Unexamined Patent Publication No. 2009-81132

The insulated wire according to one aspect of the present disclosure includes one or a plurality of linear conductors and one or a plurality of insulating layers laminated on the outer peripheral surface of the conductor, and the insulating layer contains a polyolefin and an antioxidant. The content of the antioxidant is 0.1 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the polyolefin, and the antioxidants are a phenolic antioxidant and a sulfur-containing phenolic agent. It is composed of a sulfur-based antioxidant excluding an antioxidant, and the above-mentioned phenol-based antioxidant has a less hindered phenol structure containing no sulfur or a semi-hindered phenol structure containing no sulfur, and is used in the above-mentioned antioxidant. The content of the sulfur-based antioxidant is more than 50% by mass and 90% by mass or less, and the phenol-based antioxidant having the less hindered phenol structure is represented by the following formula (1), and the semi-hindered phenol structure is described. The phenolic antioxidant having the above is represented by the following formula (2).

FIG. 1 is a schematic cross-sectional view of an insulated wire according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of the Twinax cable according to the embodiment of the present disclosure. FIG. 3 is a schematic perspective view of a coaxial cable according to an embodiment of the present disclosure. FIG. 4 is a schematic cross-sectional view of the coaxial cable of FIG.

[Problems to be solved by this disclosure]
In the above-mentioned conventional technique, if the insulating layer contains an additive such as an antioxidant, the dielectric loss tangent may increase. In the above-mentioned in-vehicle information electric wire, the influence of the dielectric loss tangent on the signal attenuation is large as a transmission line. On the other hand, in an insulating material used for an in-vehicle information wire or the like, it is desired to improve the electrical characteristics while having heat resistance.

The present disclosure has been made based on such circumstances, and an object of the present invention is to provide an insulated wire having heat resistance and having an excellent effect of suppressing an increase in dielectric loss tangent of an insulating layer.

[Effect of this disclosure]
According to the present disclosure, it is possible to provide an insulated wire having heat resistance and having an excellent effect of suppressing an increase in the dielectric loss tangent of the insulating layer.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.

The insulated wire according to one aspect of the present disclosure includes one or a plurality of linear conductors and one or a plurality of insulating layers laminated on the outer peripheral surface of the conductor, and the insulating layer contains a polyolefin and an antioxidant. The content of the antioxidant is 0.1 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the polyolefin, and the antioxidants are a phenolic antioxidant and a sulfur-containing phenolic agent. It is composed of a sulfur-based antioxidant excluding an antioxidant, and the above-mentioned phenol-based antioxidant has a less hindered phenol structure containing no sulfur or a semi-hindered phenol structure containing no sulfur, and is used in the above-mentioned antioxidant. The content of the sulfur-based antioxidant is more than 50% by mass and 90% by mass or less, and the phenol-based antioxidant having the less hindered phenol structure is represented by the following formula (1), and the semi-hindered phenol structure is described. The phenolic antioxidant having the above is represented by the following formula (2).

（式（１）及び（２）中、Ｒ^１～Ｒ^４はメチル基である。Ｒ^５は置換基である。）

(In formulas (1) and (2), R ¹ to R ⁴ are methyl groups. R ⁵ is a substituent.)

In the insulated wire, the insulating layer contains a polyolefin having a low polarity, so that the dielectric loss tangent can be satisfactorily reduced. Further, the insulating layer is a sulfur-based antioxidant excluding a sulfur-containing phenolic antioxidant, and a less hindered phenol structure represented by the above formula (1) or a semi-hindered phenol represented by the above formula (2). By containing a phenolic antioxidant having a structure and having the content of the sulfur-based antioxidant in the above range, the high temperature environment of the insulating layer is suppressed while suppressing the deterioration due to heat of the polyolefin and the increase in the dielectric adjacency. The heat resistance, which is the durability underneath, can be improved. Therefore, the insulated wire has heat resistance and is excellent in the effect of suppressing an increase in the dielectric loss tangent of the insulating layer.

（式（３）及び（４）中、Ｘ^１は－Ｓ－又は－ＮＨ－、Ｒ^６はアルキル基である。）
当該絶縁電線が上記式（３）又は下記式（４）で表される硫黄系酸化防止剤を含有することで、耐熱性をより向上することができる。 It is preferable that the sulfur-based antioxidant is represented by the following formula (3) or the following formula (4).

(In the formulas (3) and (4), X ¹ is -S- or -NH-, and R ⁶ is an alkyl group.)
The heat resistance can be further improved by containing the sulfur-based antioxidant represented by the above formula (3) or the following formula (4) in the insulated wire.

The polyolefin is preferably polypropylene. When the polyolefin is polypropylene, the effect of reducing the dielectric loss tangent of the insulating layer can be further improved.

It is preferable that the insulating layer further contains a metal damage inhibitor. When the insulating layer further contains a metal damage inhibitor, metal damage can be suppressed and oxidative deterioration of the polyolefin can be suppressed. Therefore, the dielectric loss tangent of the insulating layer can be further reduced. Here, "metal damage" generally means that oxidative deterioration of a material is promoted by the catalytic action of a metal in contact with the metal.

It is preferable that the dielectric loss tangent of the insulating layer is 2.7 × 10 ^-4 or less when a high frequency electric field having a frequency of 10 GHz is applied. When the dielectric loss tangent of the insulating layer is within the above range when a high frequency electric field having a frequency of 10 GHz is applied, the effect of reducing transmission loss can be sufficiently improved.

Another aspect of the present disclosure is an information transmission cable including one or more of the insulated wires.

Since the information transmission cable includes the insulated wire, it has heat resistance and is excellent in the effect of suppressing an increase in the dielectric loss tangent of the insulating layer. Therefore, the information transmission cable can improve durability and reduce transmission loss in a high temperature environment.

[Details of Embodiments of the present disclosure]
Hereinafter, the insulated electric wire and the information transmission cable according to the embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate.

<Insulated wire>
The insulated wire includes one or a plurality of linear conductors and one or a plurality of insulating layers laminated on the outer peripheral surface of the conductor. FIG. 1 is a schematic cross-sectional view of an insulated wire according to an embodiment of the present disclosure. As shown in FIG. 1, the insulated wire 1 includes a linear conductor 2 and a single insulating layer 3 laminated on the outer peripheral surface of the conductor 2.

[conductor]
The conductor 2 is, for example, a circular wire having a circular cross section, but may be a square wire having a square cross section, a flat wire having a rectangular cross section, or a stranded wire obtained by twisting a plurality of strands.

As the material of the conductor 2, a metal having high conductivity and high mechanical strength is preferable. Examples of such metals include copper, copper alloys, aluminum, aluminum alloys, nickel, silver, soft iron, steel, stainless steel and the like. The conductor 2 is a material obtained by forming these metals in a linear shape, or a material having a multilayer structure in which such a linear material is coated with another metal, for example, nickel-coated copper wire, silver-coated copper wire, or copper-coated aluminum. Wires, copper-coated steel wires and the like can be used.

As the lower limit of the average cross-sectional area of the conductor 2, 0.01 mm ² is preferable, and 0.1 mm ² is more preferable. On the other hand, as the upper limit of the average cross-sectional area of the conductor 2, 10 mm ² is preferable, and 5 mm ² is more preferable. If the average cross-sectional area of the conductor 2 is less than the above lower limit, the volume of the insulating layer 3 with respect to the conductor 2 may increase, and the volumetric efficiency of the coil or the like formed by using the insulated wire may decrease. On the contrary, if the average cross section of the conductor 2 exceeds the above upper limit, the insulating layer 3 must be formed thick in order to sufficiently reduce the dielectric constant, and the diameter of the insulated wire may be unnecessarily increased. be. The "average cross-sectional area" of the conductor means a value obtained by measuring the cross-sectional area of 10 conductors at an arbitrary position and averaging them.

[Insulation layer]
The insulating layer 3 is formed on the outer peripheral surface of the conductor 2.

The insulating layer 3 contains a polyolefin and an antioxidant.

Since the insulating layer 3 contains a polyolefin having a low polarity, the dielectric loss tangent can be satisfactorily reduced. Examples of the polyolefin include polypropylene, polypropylene-based thermoplastic elastomer, reactor-type polypropylene-based thermoplastic elastomer, dynamically cross-linked polypropylene-based thermoplastic elastomer, polyethylene (high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE)). , Low density polyethylene (LDPE), ultra low density polyethylene (VLDPE)), ethylene-propylene copolymer, polymethylpentene, ethylene-propylene rubber and the like can be used. "High density polyethylene (HDPE)" refers to polyethylene having a density of 0.942 g / cm ³ or more. "Linear low density polyethylene (LLDPE)" refers to polyethylene having a density of 0.910 g / cm ³ or more and less than 0.930 g / cm ³ and obtained by copolymerizing ethylene and α-olefin. .. "Low density polyethylene (LDPE)" refers to polyethylene having a density of 0.910 g / cm ³ or more and less than 0.930 g / cm ³ and obtained by polymerizing ethylene by a high-pressure polymerization method. "Ultra low density polyethylene (VLDPE)" refers to polyethylene having a density of 0.870 g / cm ³ or more and less than 0.910 g / cm ³ . Examples of the "polymethylpentene" include homopolymers of 4-methyl-1-pentene and copolymers of 4-methyl-1-pentene and 3-methyl-1-pentene or other α-olefins. .. Examples of this α-olefin include propylene, butene, pentene, hexene, heptene, octene and the like.

Among these, polypropylene is preferable as the polyolefin, and polypropylene having a melting point of 140 ° C. or higher is more preferable. Examples of polypropylene include homopolypropylene, random polypropylene, block polypropylene and the like. Homopolypropylene is a homopolymer of propylene. Examples of the random polypropylene include a copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms). The block polypropylene is a resin composed of homopolypropylene as a main component, a random copolymer elastomer as a copolymer component, and an ethylene polymer as an optional component. Among these, block polypropylene is more preferable. When the polyolefin is such polypropylene, the effect of reducing the dielectric loss tangent of the insulating layer and the heat resistance can be further improved. The "main component" means the component having the highest content.

The lower limit of the polyolefin content in the insulating layer 3 is preferably 95.0% by mass, more preferably 98.0% by mass. If the content of the polyolefin is less than the lower limit, it may be difficult to satisfactorily reduce the dielectric loss tangent of the insulating layer. On the other hand, the upper limit of the polyolefin content is preferably 99.9% by mass, more preferably 99.5% by mass. If the content of the polyolefin exceeds the above upper limit, the content of the antioxidant or the like in the insulating layer becomes insufficient, and the effect of improving the heat resistance in the insulating layer may not be sufficiently enhanced.

The insulating layer 3 may contain a resin other than the polyolefin. For example, polytetrafluoroethylene, acrylic resin, fluororubber, or the like may be added as a processability improver in the range of 0.1% by mass to 5.0% by mass.

(Antioxidant)
The antioxidant is for preventing the oxidation of the insulating layer 3. The above-mentioned antioxidant is composed of a phenol-based antioxidant and a sulfur-based antioxidant excluding a sulfur-containing phenol-based antioxidant. The insulated wire contains a polyolefin that is easily oxidatively deteriorated. The antioxidant is insulated by being composed of a phenolic antioxidant and a sulfur-based antioxidant excluding a sulfur-containing phenolic antioxidant. The heat resistance of the layer can be further improved.

The phenolic antioxidant has a sulfur-free reshindered phenol structure represented by the following formula (1) or a sulfur-free semi-hindered phenol structure represented by the following formula (2). The above-mentioned phenolic antioxidant has a sulfur-free reshindered phenol structure represented by the above formula (1) or a sulfur-free semi-hindered phenol structure represented by the above formula (2), thereby having heat resistance. In addition to having properties, it has an excellent effect of suppressing an increase in the dielectric loss tangent of the insulating layer.

In the above formulas (1) and (2), R ¹ to R ⁴ are methyl groups. R ⁵ is a substituent.

Specific examples of the antioxidant having a semi-hindered phenol structure containing no sulfur include triethylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (for example, Adecastab AO-70) manufactured by Adeca, Adecastab AO-80 manufactured by Adeca, etc.), bis [3,3-bis (3-tert-butyl-4-hydroxyphenyl) butyric acid] ethylene (for example, Hostanox O3 manufactured by Clarianto Chemicals) , Ethylenebis (oxyethielene) bis [3- (5-tert-butyl-hydroxy-m-tolyl) propionate] (for example, Irganox 245 manufactured by BASF Japan), "Triethylene glycol bis [3- (3- (3- (3-) tert-Butyl-4-hydroxy-5-methylphenyl) propionate ”(Rowinox GP 45 manufactured by addivant), 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane (for example, Sumilizer GA-80 manufactured by Sumitomo Chemical Co., Ltd.).

Specific examples of the antioxidant having a sulfur-free less hindered phenol structure include 4,4'-butylidenebis (3-methyl-6-tert-butylphenol) (for example, Nocrack manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.). Examples thereof include NS-30, 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane (for example, Adeka Stub AO-30 manufactured by Adeka Corporation).

The sulfur-based antioxidant is preferably represented by the following formula (3) or the following formula (4). The heat resistance can be further improved by containing the sulfur-based antioxidant represented by the above formula (3) or the following formula (4) in the insulated wire.

In the above formulas (3) and (4), X ¹ is -S- or -NH-, and R ⁶ is an alkyl group.

Examples of the sulfur-based antioxidant represented by the following formula (3) include 2-mercaptobenzothiazole (for example, Sunseller M manufactured by Sanshin Chemical Co., Ltd.) and 2-mercaptobenzimidazole (for example, Sumitomo Chemical Co., Ltd. Sumilyzer MB). Can be mentioned.

Examples of the sulfur-based antioxidant represented by the following formula (4) include distearyl thiodipropionate (Irganox PS802FL manufactured by BASF) and pentaerythritol tetrakis- (3-dodecylthiopropionate) (manufactured by Cipro Kasei Co., Ltd.). Seanox 412s), Zidodecylthiodipropionate (Sipro Kasei Co., Ltd. Seanox DL), Ditetradecylthiodipropionate (Cipro Kasei Co., Ltd. Seanox DM), Dioctadecylthiodipropionate (Cipro Kasei Co., Ltd. Sea) Knox DS) and the like.

Among these sulfur-based antioxidants, 2-mercaptobenzothiazole and pentaerythritol tetrakis- (3-dodecylthiopropionate) are from the viewpoint of further improving the effect of reducing the dielectric loss tangent of the insulating layer and the heat resistance. preferable.

The lower limit of the content of the sulfur-based antioxidant in the antioxidant is more than 50% by mass, preferably 55% by mass, and more preferably 60% by mass. If the content of the sulfur-based antioxidant is not less than the above lower limit, it may be difficult to improve the effect of suppressing the deterioration of the polyolefin due to heat and the increase of the dielectric loss tangent. On the other hand, the upper limit of the content of the sulfur-based antioxidant is 90% by mass, preferably 85% by mass, and more preferably 80% by mass. If the content of the sulfur-based antioxidant exceeds the upper limit, the effect of suppressing the increase in dielectric loss tangent is reduced, and the electrical characteristics of the insulated wire may be impaired.

The lower limit of the content of the antioxidant in the insulating layer is 0.1 part by mass, preferably 0.2 part by mass, and more preferably 0.3 part by mass with respect to 100 parts by mass of the polyolefin. If the content of the antioxidant is not less than the above lower limit, it may be difficult to improve the effect of suppressing the deterioration of the polyolefin due to heat and the increase of the dielectric loss tangent. On the other hand, the upper limit of the content of the antioxidant is 1.0 part by mass, preferably 0.9 part by mass, and more preferably 0.8 part by mass with respect to 100 parts by mass of the polyolefin. If the content of the antioxidant exceeds the upper limit, the effect of suppressing the increase in dielectric loss tangent is reduced, and the electrical characteristics of the insulated wire may be impaired.

(Metal damage inhibitor)
It is preferable that the insulating layer further contains a metal damage inhibitor. The metal damage inhibitor stabilizes metal ions by chelate formation and suppresses deterioration of the dressing resin due to metal ions, so-called metal damage. When the insulating layer further contains a metal damage inhibitor, metal damage can be suppressed and oxidative deterioration of the polyolefin can be suppressed. Therefore, the dielectric loss tangent of the insulating layer can be further reduced. The metal damage inhibitor in the present embodiment is preferably a copper damage inhibitor.

The lower limit of the melting point of the metal damage inhibitor is 200 ° C., more preferably 220 ° C. When the lower limit of the melting point of the metal damage inhibitor is within the above range, the effect of reducing the dielectric loss tangent of the insulating layer and the effect of suppressing metal damage can be improved.

The metal damage inhibitor is not particularly limited as long as it has a melting point of 200 ° C. or higher, and examples thereof include hydrazide compounds, salicylic acid derivatives, phthalic acid derivatives, triazole compound complexes, and aromatic secondary amine compounds. Can be mentioned. Examples of the salicylic acid derivative include NN'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine (product name: Irganox MD1024, melting point 225 ° C.), 3- (N). -Salicyloyl) Amino-1,2,4-triazole (Product name: Adecastab CDA-1, melting point 315 ° C to 325 ° C), decamethylene dicarboxylic acid disalicyloyl hydrazide (Product name: Adecastab CDA-6, melting point 209 ° C) ~ 215 ° C.) and the like. Examples of the phthalic acid derivative include isophthalic acid bis (2-phenoxypropionylhydrazide) (product name: CUNOX, melting point 225 ° C.) and the like. Examples of the complex of the triazole-based compound include a complex containing 2-hydroxy-N-1H-1,2,4-triazole-3-ylbenzamide as a main component (product name: Adecaster CDA-1M, melting point 214 ° C.). Above) and the like. Examples of the aromatic secondary amine compound include N, N'-di-2-naphthyl-p-phenylenediamine (product name: Nocrack White, melting point 225 ° C. or higher) and the like.

Among these, hydrazine compounds, salicylic acid derivatives, phthalic acid derivatives or combinations thereof are preferable from the viewpoint of further improving the effect of suppressing metal damage, and NN'-bis [3- (3,5-di-t-). Butyl-4-hydroxyphenyl) propionyl] hydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole and bis isophthalate (2-phenoxypropionylhydrazide) are more preferred. In addition, the above-mentioned metal damage inhibitor may be used alone or in combination of two or more.

As the lower limit of the content of the metal damage inhibitor with respect to 100 parts by mass of the polyolefin, 0.01 part by mass is preferable, 0.02 part by mass is more preferable, and 0.03 part by mass is further preferable. If the mass ratio of the metal damage inhibitor does not reach the lower limit, it may be difficult to improve the effect of suppressing metal damage. On the other hand, as the upper limit of the mass ratio of the metal damage inhibitor, 1.0 part by mass is preferable, and 0.9 part by mass is more preferable. If the mass ratio of the metal damage inhibitor exceeds the upper limit, the additive in the insulating layer precipitates on the surface from the resin and crystallizes, which is called bloom, which may impair the quality of the insulating layer.

(Other ingredients)
In addition to the polyolefin and the antioxidant, the insulating layer may contain, for example, a flame retardant, a flame retardant, a pigment, an antioxidant and the like.

The flame retardant imparts flame retardancy to the insulating layer. Examples of the flame retardant include halogen-based flame retardants such as chlorine-based flame retardants and brominated flame retardants.

The flame retardant aid further improves the flame retardancy of the insulating layer. Examples of the flame retardant aid include antimony trioxide and the like.

The pigment colors the insulating layer. As the pigment, various known pigments can be used, and examples thereof include titanium oxide and the like.

As the upper limit of the dielectric loss tangent of the insulating layer when a high frequency electric field having a frequency of 10 GHz is applied, 2.7 × 10 ^-4 is preferable, and 2.5 × 10 ^-4 is more preferable. When the range of the dielectric loss tangent of the insulating layer is within the above range, the effect of reducing the transmission loss can be sufficiently improved.

The upper limit of the relative permittivity of the insulating layer is preferably 2.5, more preferably 2.3. If the relative permittivity exceeds the upper limit, the dielectric loss tangent may become too large, the transmission loss may not be sufficiently reduced, and a sufficient transmission speed may not be obtained.

The above-mentioned "dielectric loss tangent" and "relative permittivity" are values measured according to a method according to JIS-R1641 (2007), respectively.

The lower limit of the average thickness of the insulating layer 3 is preferably 50 μm, more preferably 100 μm. On the other hand, the upper limit of the average thickness of the insulating layer 3 is preferably 1500 μm, more preferably 1000 μm. If the average thickness of the insulating layer 3 is less than the above lower limit, the insulating property may be deteriorated. On the contrary, when the average thickness of the insulating layer 3 exceeds the above upper limit, the volumetric efficiency of the cable or the like formed by using the insulated wire may be lowered. The "average thickness" of the insulating layer means a value obtained by measuring the thickness of the insulating layer at an arbitrary position at 10 points and averaging the thickness.

[Manufacturing method of insulated wire]
Next, a method of manufacturing the insulated wire will be described. In the insulated wire, the insulating layer 3 is formed by extrusion molding. This method for manufacturing an insulated wire includes a step (extrusion step) of extruding and covering the outer peripheral surface of the conductor 2 with a resin composition for forming an insulating layer. Since the structure of the resin composition for forming the insulating layer is the same as that of the insulating layer described above, the description thereof will be omitted.

<Advantage>
The insulated wire has heat resistance and is excellent in suppressing an increase in the dielectric loss tangent of the insulating layer.

<Cable for information transmission>
The information transmission cable includes one or more of the insulated wires. Examples of the information transmission cable include a differential transmission cable and a coaxial cable.

[Cable for differential transmission]
The differential transmission cable is preferably used as a cable for transmitting a differential signal in a field where high-speed communication is required. Examples of the cable for differential transmission include a Tinax cable having a Tinax structure.

FIG. 2 is a schematic cross-sectional view of a Twinax cable, which is an embodiment of the information transmission cable. As shown in FIG. 2, the twinax cable 10 has a twinax structure having a pair of insulated wires each consisting of a first insulated wire 1a and a second insulated wire 1b. The first insulated wire 1a includes a linear conductor 2a and a single insulating layer 3a laminated on the outer peripheral surface of the conductor 2a. The second insulated wire 1b includes a linear conductor 2b and a single insulating layer 3b laminated on the outer peripheral surface of the conductor 2b. The insulated wire is used for the first insulated wire 1a and the second insulated wire 1b. Further, the twinax cable 10 includes a train wire 5 which is a third conductor, and a shield tape 30 arranged so as to cover the insulated wire 1a, the insulated wire 1b, and the train wire 5.

When a twinax cable is used as the information transmission cable, signal transmission with high accuracy and high speed can be efficiently performed. Further, by grounding the train wire 5, it is possible to prevent charging in the twinax cable 10. Further, by including the shield tape 30, it is possible to prevent interference of electromagnetic noise from the outside and reduce mutual interference between each signal line of the signal line pair.

The shield tape 30 is provided with a conductive layer on one side of an insulating film made of a resin such as a polyvinyl chloride resin or a flame-retardant polyolefin resin. As the shield tape 30, a tape-like body such as a copper-deposited PET tape can be used. By including the shield tape 30, it is possible to prevent interference of electromagnetic noise from the outside and reduce mutual interference between each signal line of the signal line pair. In the present embodiment, the shield tape 30 is arranged so as to cover the outer peripheral side of the insulating layers 3a and 3b. The shield tape 30 wraps the first insulated wire 1a, the second insulated wire 1b, and the train wire 5 so as to relatively fix the positional relationship between the first insulated wire 1a and the second insulated wire 1b. Is arranged on the outer peripheral side of the first insulating layer 3a and the second insulating layer 3b.

[Manufacturing method of Twinax cable]
The method for manufacturing a twinax cable, which is an embodiment of the information transmission cable, is, for example, to bundle a first insulated wire and a second insulated wire, arrange a train wire as a third conductor, and arrange the train wire. A twinax cable is manufactured by wrapping a shield tape around the outer circumference.

[coaxial cable]
A coaxial cable according to an embodiment of the information transmission cable includes the above-mentioned insulated wire, an outer conductor covering the peripheral surface of the insulated wire, and an outer cover layer covering the peripheral surface of the outer conductor. The insulated wire includes one conductor and one insulating layer covering the peripheral surface of the conductor. The embodiment of the coaxial cable will be described with reference to FIGS. 3 and 4.

The coaxial cable 40 of FIGS. 3 and 4 includes the insulated wire 1 provided with the conductor 2 and the insulating layer 3 covering the peripheral surface of the conductor 2, the external conductor 45 covering the peripheral surface of the insulated wire 1, and the outside. The outer cover layer 46 that covers the peripheral surface of the conductor 45 is provided. That is, the coaxial cable 40 has a structure in which the conductor 2, the insulating layer 3, the outer conductor 45, and the outer cover layer 46 are concentrically laminated in a cross-sectional shape. Since the information transmission cable is a coaxial cable 40, the diameter can be reduced. Since the insulated wire 1, the conductor 2, and the insulating layer 3 are the same as the insulated wire 1 in FIG. 1, they are designated by the same reference numerals and the description thereof will be omitted.

The outer conductor 45 serves as a ground and functions as a shield for preventing electrical interference from other circuits. The outer conductor 45 covers the outer surface of the insulating layer 3. Examples of the outer conductor 45 include a braided shield, a horizontal winding shield, a tape shield, a conductive plastic shield, a metal tube shield, and the like. Above all, from the viewpoint of high frequency shielding property, a braided shield and a tape shield are preferable. When a braided shield or a metal tube shield is used as the outer conductor 45, the number of shields may be appropriately determined according to the shield to be used and the desired shielding property, and even if it is a single shield, it may be a double shield. It may be a multiple shield such as a triple shield or a triple shield.

The outer cover layer 46 protects the conductor 2 and the outer conductor 45, and imparts functions such as flame retardancy and weather resistance in addition to insulating properties. The outer cover layer 46 may contain a thermoplastic resin as a main component.

Examples of the thermoplastic resin include polyvinyl chloride, low-density polyethylene, high-density polyethylene, foamed polyethylene, polyolefins such as polypropylene, polyurethane, fluororesin and the like. Among these, polyolefin and polyvinyl chloride are preferable from the viewpoint of cost and ease of processing. The above-mentioned materials exemplified may be used alone or in combination of two or more, and may be appropriately selected according to the function to be realized by the outer layer 46.

[Manufacturing method of coaxial cable]
The coaxial cable 40 is formed by covering the insulated wire 1 with an outer conductor 45 and an outer layer 46.

The coating with the outer conductor 45 can be performed by a known method depending on the shielding method to be applied. For example, the braided shield can be formed by inserting the insulating electric wire 1 into the tubular braid and then reducing the diameter of the braid. The horizontal winding shield can be formed by winding a metal wire such as a copper wire around the insulating layer 3. The tape shield can be formed by wrapping a conductive tape such as a laminated tape of aluminum and polyester around the insulating layer 3.

The coating with the outer cover layer 46 can be performed by the same method as the coating of the conductor 2 with the insulating layer 3 of the insulated wire 1. Further, the thermoplastic resin or the like may be applied to the peripheral surfaces of the insulated wire 1 and the outer conductor 45.

<Advantage>
Since the information transmission cable includes the insulated wire, it has heat resistance and is excellent in the effect of suppressing an increase in the dielectric loss tangent of the insulating layer. Therefore, the information transmission cable can improve durability and reduce transmission loss in a high temperature environment.

[Other embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not limited to the configuration of the above-described embodiment, but is indicated by the scope of claims and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The insulated wire may have an insulating layer foamed. By foaming the insulating layer, the dielectric constant can be lowered, and the thin insulating layer can be matched by the predetermined characteristic impedance (50Ω, 100Ω, etc.), and the diameter of the cable can be reduced.

The information transmission cable may be a multi-core cable in which a plurality of twinax cables are further covered with an outer cover. By using a multi-core cable, it is possible to transmit a signal with a larger capacity than that of a Twinax cable.

The conductor can also be formed from a stranded wire obtained by twisting a plurality of metal wires. In this case, a plurality of types of metal wires may be combined. The number of twists is generally 7 or more.

The insulated wire may have a primer layer that is directly laminated on the conductor. As the primer layer, a layer obtained by cross-linking a cross-linking resin such as ethylene that does not contain a metal hydroxide can be preferably used. By providing such a primer layer, it is possible to prevent a decrease in the peelability of the insulating layer and the conductor over time and prevent a decrease in the efficiency of the wiring work.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Insulation layer No. 1 to No. 14]
Polypropylene as the main component polyolefin ("Novatec EA9" manufactured by Japan Polypropylene Corporation) and the metal damage inhibitor shown below are mixed so that the content (part by mass) is as shown in Table 1 for the insulating layer. A resin composition was obtained. Sheet-shaped insulating layers No. 1 to No. 14 obtained by press-molding the resin composition for an insulating layer were produced. The conditions for press molding were preheating at 180 ° C. for 5 minutes. After that, the pressure was further increased at that temperature, and the mixture was held for 5 minutes.

N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine (Fuji Film Wako Pure Chemical Industries, Ltd.) represented by the following (K-3) as a metal damage inhibitor "Irganox MD1024" manufactured by the company, melting point 60 ° C to 67 ° C) was used.

Ethylene bis (oxyethielene) bis [3- (5-tert-butyl-hydroxy-m-tolyl) propionate] (for example, BASF Japan Ltd.) as a sulfur-free semi-hindered phenolic antioxidant having a phenolic structure. Irganox 245) manufactured by Irganox 245) was used.
4,4'-Butylidenebis (3-methyl-6-tert.-Butylphenol) ("Nocrack NS-30" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. as a sulfur-based antioxidant having a sulfur-free lesshindard phenol structure. ) Was used.
Further, as a phenolic antioxidant having a hindered phenol structure, octadecyl-3- (3,5-2-tert.-butyl-4-hydroxyphenyl) -propionate ("Irganox 1076" manufactured by BASF Japan Ltd.). Was used.

As a sulfur-based antioxidant, 2-mercaptobenzothiazole (“Sunceller M” manufactured by Sanshin Chemical Industry Co., Ltd.) corresponding to the above formula (3) and distearyl thiodipropionate corresponding to the above formula (4) (BASF) Irganox PS802FL) manufactured by Irganox was used. Further, 4,4'-thiobis (6-tert-butyl-m-cresol) (Sumirazer WX-R manufactured by Sumitomo Chemical Co., Ltd.) was used as an antioxidant which is a sulfur-containing phenolic antioxidant.

<Evaluation>
The insulating layer No. obtained as described above. 1 to No. For No. 14, the dielectric loss tangent and the relative permittivity were measured, and the heat aging test was performed.

(Measurement of dielectric loss tangent and relative permittivity)
The dielectric loss tangent (dielectric contact) and relative permittivity when a high frequency electric field having a frequency of 10 GHz was applied to the obtained sheet-shaped sample was measured according to a method according to JIS-R1641 (2007). The measurement was performed three times, and the average value was calculated.

(Heat-resistant aging test)
Insulation layer No. 1 to No. A heat-resistant aging test was carried out on No. 14 according to the following procedure in accordance with the JASO D611 standard. The sheet was punched into a dumbbell shape (JIS No. 3), placed in constant temperature baths set at 160 ° C, 180 ° C, and 200 ° C, and the time until the tensile elongation fell below 100% was determined and used as the life. An Arrhenius plot was performed based on the results, and the temperature at which the tensile elongation was 100% was estimated in the aging test for 10000 hours, the heat resistant temperature was set to 10000 hours, and 105 ° C. or higher was accepted.

Table 1 shows the results of the dielectric loss tangent and relative permittivity measurements and the heat aging test.

From the results in Table 1 above, the content of the antioxidant is 0.1 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the polyolefin, and the antioxidants are a phenolic antioxidant and sulfur. It is composed of a sulfur-based antioxidant excluding the contained phenol-based antioxidant, and the above-mentioned phenol-based antioxidant has a less hindered phenol structure represented by the above formula (1) or a semi represented by the above formula (2). No. which has a hindered phenol structure and has a content of the sulfur-based antioxidant in the antioxidant of more than 50% by mass and 90% by mass or less. 1 to No. The insulating layer of No. 6 had a high inhibitory effect on the increase in dielectric loss tangent, and had a heat resistant temperature of 105 ° C. or higher for 10,000 hours in the heat resistant aging test. On the other hand, the content of the sulfur-based antioxidant in the antioxidant is 50% by mass or less or more than 90% by mass. 7-No. No. 12 insulating layer and No. 1 containing a sulfur-containing phenolic antioxidant as an antioxidant. 13-No. The insulating layer 14 had a low inhibitory effect on the increase in dielectric loss tangent, or had a heat resistant temperature of less than 105 ° C. for 10000 hours in the heat resistant aging test.

From the above, it can be seen that the insulated wire has heat resistance and is excellent in suppressing the increase in the dielectric loss tangent of the insulating layer.

1, 1a, 1b Insulated wire 2, 2a, 2b Conductor 3, 3a, 3b Insulated layer 5 Train wire 10 Twinax cable 30 Shielding tape 40 Coaxial cable 45 External conductor 46 Outer layer

Claims (6)

With one or more linear conductors,
It is provided with one or more insulating layers laminated on the outer peripheral surface of the conductor.
The insulating layer contains a polyolefin and an antioxidant,
The content of the antioxidant is 0.1 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the polyolefin.
The above-mentioned antioxidant is composed of a phenol-based antioxidant and a sulfur-based antioxidant excluding a sulfur-containing phenol-based antioxidant.
The above-mentioned phenolic antioxidant has a sulfur-free less hindered phenol structure or a sulfur-free semi-hindered phenol structure, and has a sulfur-free semi-hindered phenol structure.
The content of the sulfur-based antioxidant in the antioxidant is more than 50% by mass and 90% by mass or less.
The above-mentioned phenolic antioxidant having a less hindered phenol structure is represented by the following formula (1).
An insulated wire in which the above-mentioned phenolic antioxidant having a semi-hindered phenol structure is represented by the following formula (2).

(In formulas (1) and (2), R ¹ to R ⁴ are methyl groups. R ⁵ is a substituent.) The insulated wire according to claim 1, wherein the sulfur-based antioxidant is represented by the following formula (3) or the following formula (4).

(In the formulas (3) and (4), X ¹ is -S- or -NH-, and R ⁶ is an alkyl group.) The insulated wire according to claim 1 or 2, wherein the polyolefin is polypropylene. The insulated wire according to claim 1, claim 2 or claim 3, wherein the insulating layer further contains a metal damage inhibitor. The insulated wire according to any one of claims 1 to 4, wherein the dielectric loss tangent of the insulating layer is 2.7 × 10 ^-4 or less when a high frequency electric field having a frequency of 10 GHz is applied. An information transmission cable including one or more insulated wires according to any one of claims 1 to 5.

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