WO2011048974A1

WO2011048974A1 - Foamed electric wire and transmission cable comprising same

Info

Publication number: WO2011048974A1
Application number: PCT/JP2010/067847
Authority: WO
Inventors: 亮渡部
Original assignee: 株式会社フジクラ
Priority date: 2009-10-23
Filing date: 2010-10-12
Publication date: 2011-04-28
Also published as: JPWO2011048974A1

Abstract

Disclosed is a foamed electric wire comprising an electric conductor and a foamed insulation layer that covers the conductor, wherein the foamed insulation layer is obtained by melt kneading a resin compound including a base resin containing a propylene-based resin and having a melt strength of 20-55mN and a haul-off speed greater than or equal to 50m/min. at break, a chemical foaming agent, and a copper corrosion inhibitor, such that the chemical foaming agent is azodicarbonamide and the copper corrosion inhibitor is of at least one type selected from the group consisting of 3-(N-salicyloyl) amino-1,2,4-triazole, 2',3-Bis [3-(3,5 di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide, and decamethylene dicarboxylic di-salicyloyl hydrazide.

Description

Foamed electric wire and transmission cable having the same

The present invention relates to a foamed electric wire and a transmission cable having the same.

The foam insulation layer of foamed electric wires used for USB 3.0 cables, HDMI cables, Infiniband cables, micro USB cables, etc., has a small diameter, high heat resistance, and can be finely foamed. Is required.

As such a foamed insulating layer, an ethylene-propylene copolymer having a melt tension at break of 5.0 g (49 mN) or more and a melt mass flow rate at 190 ° C. of 2.16 kg of 1.0 g / 10 min or more is conventionally used. By using a chemical foaming agent such as azodicarbonamide and a copper damage inhibitor such as 3- (N-salicyloyl) amino-1,2,4-triazole added to the coalesced foam, It has been proposed to stably and reliably form an insulating layer (Patent Document 1 below).

JP 2006-236978 A

By the way, with the reduction of the diameter of the transmission cable, further miniaturization of the foam cell in the foam insulation layer is required.

However, in the foamed insulating layer described in Patent Document 1, foamed cells may be coarsened, and sufficiently fine foamed cells may not be obtained.

Also, the foamed insulating layer is required to have heat resistance, and it is desired that the foamed insulating layer can be used continuously for a long time even in a high temperature environment.

The present invention has been made in view of the above circumstances, and provides a foamed electric wire capable of obtaining a sufficiently fine foamed cell and capable of being continuously used over a long period of time even in a high temperature environment, and a transmission cable having the same. With the goal.

In order to solve the above problems, the present inventor conducted various experiments paying attention to the melt tension at the time of fracture of the base resin. At this time, the inventor considered that when the melt tension at the time of fracture was lower than the melt tension described in Patent Document 1, the amount of attenuation increased. However, according to the inventor's research, depending on the combination of the copper damage inhibitor added to the base resin containing the propylene resin and the chemical foaming agent, the coarsening of the foam cell is sufficiently suppressed, and the foam cell is sufficiently fine. It became clear that the amount of attenuation tends to be suppressed. Further, the above-mentioned specific copper damage inhibitor sufficiently suppresses the deterioration of the propylene-based resin by the conductor, which is considered to allow continuous use even in a high temperature environment. As a result of further earnest studies, the present inventor has found that the above-described problems can be solved by the following invention.

That is, the present invention is a foamed electric wire comprising a conductor and a foamed insulating layer covering the conductor, wherein the foamed insulating layer contains a propylene resin, has a melt tension at break of 20 to 55 mN, and a take-off speed. Obtained by melting and kneading a resin composition containing a base resin having a viscosity of 50 m / min or more, a chemical foaming agent, and a copper damage inhibitor, wherein the chemical foaming agent is azodicarbonamide, The agent is 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide And at least one selected from the group consisting of decamethylenedicarboxylic acid disalicyloyl hydrazide.

According to this foamed electric wire, sufficiently fine foamed cells can be obtained, and it can be used continuously for a long time even in a high temperature environment.

In the foamed electric wire, it is preferable that the resin composition further includes silica particles. In this case, even if the resin composition is continuously melted and kneaded for a long time, the decrease in the discharge amount can be sufficiently suppressed, and the production efficiency of the foamed electric wire can be more sufficiently improved.

Further, the present invention is a transmission cable having the above foamed electric wire. According to this transmission cable, a sufficiently fine foam cell can be obtained, and it can be used continuously for a long time even in a high-temperature environment. Therefore, it is easy to obtain a transmission cable with reduced attenuation, and the length of the transmission cable is increased. Life can be extended.

In the present invention, “melt tension at break” refers to melt tension measured using a capillary rheometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Specifically, “melt tension at break” is defined as follows. That is, first, a base capillary is filled into a flat capillary having an inner diameter of 1.0 mm and a length of 10 mm. Thereafter, in the capillary rheometer, the piston speed is set to 5 mm / min, the barrel inner diameter is 9.55 mm, the take-up acceleration is set to 400 m / min ² , and the temperature of the barrel, the capillary, and the thermostat immediately after the barrel is set to 200 ° C. Then, the base resin is filled in the barrel, and after 5 minutes preheating, piston extrusion is started at the piston speed. Then, the base resin is accelerated at the above-mentioned take-up acceleration and taken up, and the tension when it is broken is measured. The average value of the measured tension values obtained by performing this measurement 10 times is defined as “melt tension at break”.

According to the present invention, a foamed electric wire that can obtain sufficiently fine foamed cells and can be used continuously for a long period of time even in a high-temperature environment, and a transmission cable having the same are provided.

It is a partial side view which shows one Embodiment of the transmission cable of this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. It is an end view which shows other embodiment of the transmission cable of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a partial side view showing an embodiment of a transmission cable according to the present invention, and shows an example in which a foamed electric wire is applied to a coaxial cable as a transmission cable. FIG. 2 is a sectional view taken along line II-II in FIG. As shown in FIG. 1, the transmission cable 10 is a coaxial cable, and includes a foamed electric wire 5, an outer conductor 3 that surrounds the foamed electric wire 5, and a sheath 4 that covers the outer conductor 3. The foamed electric wire 5 includes an inner conductor 1 and a foamed insulating layer 2 that covers the inner conductor 1.

Here, the foam insulation layer 2 includes a base resin containing a propylene-based resin, a melt tension at break of 20 mN to 55 mN and a take-up speed of 50 m / min or more, a chemical foaming agent, and a copper damage preventing agent. It is obtained by melt-kneading the resin composition containing. Here, azodicarbonamide is used as the chemical foaming agent, and 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide and decamethylenedicarboxylic acid disalicyloyl hydrazide are used.

According to the foamed electric wire 5 having such a configuration, a sufficiently fine foam cell can be obtained, and it can be continuously used over a long period of time even in a high temperature environment. Therefore, according to the transmission cable 10 having the foamed electric wire 5, it becomes easy to obtain the transmission cable 10 in which the attenuation amount is suppressed, and the life of the transmission cable 10 can be extended.

Next, a method for manufacturing the transmission cable 10 will be described.

First, a method for manufacturing the foamed electric wire 5 will be described.

<Inner conductor>
First, the inner conductor 1 is prepared. Examples of the internal conductor 1 include metal wires such as copper wires, copper alloy wires, and aluminum wires. In addition, a material obtained by plating the surface of the metal wire with tin, silver or the like can be used as the internal conductor 1. The inner conductor 1 can be a single wire or a stranded wire.

<Foam insulation layer>
Next, the foamed insulating layer 2 is formed on the inner conductor 1.

In order to form the foam insulation layer 2, a base resin, a chemical foaming agent, and a copper damage prevention agent are prepared.

(Base resin)
Here, the base resin will be described first.

The base resin includes a propylene resin. Propylene-type resin means resin containing the structural unit derived from propylene. Therefore, such propylene-based resins include homopolypropylene obtained by homopolymerization of propylene, copolymers of olefins other than propylene and propylene, and mixtures of two or more thereof. Examples of olefins other than propylene include ethylene, 1-butene, 2-butene, 1-hexene, 2-hexene and the like. Among them, α-olefins such as ethylene, 1-butene, and 1-hexene are preferably used from the viewpoint of realizing more sufficient miniaturization of the foamed cell and obtaining better heat resistance, and more preferably ethylene. .

When the propylene-based resin is a copolymer of olefin other than propylene and propylene, the copolymer includes a random copolymer in addition to the block copolymer, but the copolymer includes a block copolymer. It is preferable. When the copolymer contains a block copolymer, the foamed cells can be more sufficiently miniaturized and better heat resistance can be obtained as compared with the case where the block copolymer is not contained.

Here, the copolymer may be composed only of a block copolymer, or may be composed of a mixture of a block copolymer and a random copolymer, but only composed of a block copolymer. Is preferred. In this case, compared with the case where a copolymer is comprised with the mixture of a block copolymer and a random copolymer, a foamed cell can be refined more fully.

The propylene resin preferably has a melting point of 150 ° C. or higher. In this case, the heat resistance of the foamed electric wire 5 is further improved as compared with the case where the melting point is less than 150 ° C. The melting point of the propylene-based resin is more preferably 160 ° C. or higher. However, the melting point of the propylene-based resin is preferably 170 ° C. or lower because the good balance between heat resistance and resistance to low temperature embrittlement and bending resistance can be maintained.

The melt tension at break of the base resin is 20 to 55 mN. When the melt tension is out of the above range, the foam cell becomes coarse.

Further, the take-off speed at the time of breaking of the base resin is 50 m / min or more, preferably 80 m / min or more, more preferably 100 m / min or more. When the take-up speed is less than 50 m / min, the foam cells are coarsened, and sufficiently fine foam cells cannot be stably obtained. However, the take-up speed at the time of breaking is preferably 200 m / min or less for the reason that fine foam cells can be stably obtained, and more preferably 150 m / min or less.

(Chemical foaming agent)
Next, the chemical foaming agent will be described.

As the chemical foaming agent, azodicarbonamide (hereinafter referred to as “ADCA”) that generates a gas such as N ₂ , NH ₃ , and CO ₂ by thermal decomposition is used. ADCA has a thermal decomposition temperature sufficiently higher than the melting point of the propylene-based resin and lower than the decomposition temperature of the propylene-based resin. Therefore, the degree of freedom of the temperature profile is high and the foaming is easily controlled. Further, when ADCA is used, sufficiently fine foam cells can be stably obtained as compared with the case of using a chemical foaming agent other than ADCA, and fluctuations in the outer diameter of the foamed insulating layer 2 can also be suppressed.

The chemical foaming agent is preferably added in an amount of 0.3 to 1 part by weight, more preferably 0.5 to 0.7 parts by weight, based on 100 parts by weight of the base resin. When the addition amount of the chemical foaming agent is within the above range, sufficiently fine foam cells can be obtained more stably.

(Copper damage prevention agent)
Next, the copper damage preventing agent will be described.

The copper damage prevention agent is for preventing deterioration of the propylene-based resin due to contact with the inner conductor 1, and the copper damage prevention agent is 3- (N-salicyloyl) amino-1,2,4- Triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide or decamethylenedicarboxylic acid disalicyloyl hydrazide is used. These can be used alone or in admixture of two or more. Among them, 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide This is preferable because finer foam cells can be obtained.

The copper damage inhibitor is preferably added in an amount of 0.01 to 1 part by weight, more preferably 0.1 to 1 part by weight, even more preferably 0.25 to 0.5 parts by weight, based on 100 parts by weight of the base resin. Add part. When the addition amount of the copper damage inhibitor is within the above range, deterioration due to heat aging is more sufficiently suppressed, and the life of the foamed electric wire 5 can be extended. In addition, an adverse effect on the signal attenuation can be reduced.

(Silica particles)
It is preferable to add silica particles to the base resin together with a copper damage inhibitor. In this case, even if the resin composition is continuously melted and kneaded for a long time, a decrease in the discharge amount can be sufficiently suppressed, and the production efficiency of the foamed electric wire 5 can be improved. As a result, the price of the foamed electric wire 5 can be reduced.

In general, it has been considered that silica particles promote the coarsening of foamed cells when used together with a copper damage inhibitor. However, when the silica particles are combined with the specific copper damage inhibitor, the foaming cell is prevented from becoming coarse, and when the silica particles are combined with a copper damage inhibitor other than the specific copper damage inhibitor, It has been clarified by research of the present inventor that coarsening tends to be promoted.

At this time, the addition amount of silica particles is preferably 0.03 to 1 part by mass with respect to 100 parts by mass of the base resin. When the addition amount of the silica particles is within the above range, it is possible to more sufficiently suppress the decrease in the discharge amount from the extruder, and more sufficiently increase the signal attenuation in the foamed electric wire 5 due to the hygroscopic property of silica. It tends to be suppressed.

(Antioxidant)
It is preferable to add an antioxidant to the base resin. In this case, heat aging characteristics and the like are further improved, and the foamed electric wire 5 can be continuously used over a longer period even in a high temperature environment. The amount of the antioxidant added to 100 parts by mass of the base resin is, for example, 0.05 to 1 part by mass.

Examples of the antioxidant include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-methylphenol, Monophenols such as 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 2,4,6-tri-tert-butylphenol, o-tert-butylphenol, 2,2′- Methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-methylene-bis- (2 , 6-di-tert-butylphenol), 4,4′-butylidene-bis- (4-methyl-6-tert-butylphenol), alkylated bisphenol, 1,3,5-trimethyl-2,4,6 -Tris (3,5 Polyphenols such as di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, n -Octadecyl-3- (4'-hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) ) Butane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1, dimethylethyl] -2,4,8,10-tetraoxa Hindered phenols such as spiro [5,5] -undecane, 4,4′-thiobis- (6-tert-butyl-3-methylphenol), 4,4′-thiobis- (6-tert-butyl) Thiol-o-cresol), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, thiobisphenols such as dialkyl / phenol / sulfide, phosphite, tris (2,4-di-tert) Phosphorus tris (nonylphenyl) such as -butylphenyl) phosphite, dilauryl thiodipropionate, distearyl thiodipropionate, distearyl-β, β-thiodibutyrate, lauryl stearyl thiodipropionate Dimyristyl-3,3′- thiodipropionate, ditridecyl-3,3′- thiodipropionate, sulfur-containing ester compound, amyl-thioglycolate, 1,1′- thiobis- (2-naphthol), Examples thereof include 2-mercaptobenzimidazole and hydrazine derivatives. These can be used alone or in combination of two or more.

When the above base resin, chemical foaming agent, copper damage inhibitor and the like are charged into an extruder and the resin composition in the extruder is melt-kneaded, first the chemical foaming agent is uniformly dispersed in the base resin, A chemical foaming agent is heated to a temperature equal to or higher than its thermal decomposition temperature to cause thermal decomposition and generate a decomposition gas. Then, the resin containing the decomposition gas is foamed while being extruded, and the inner conductor 1 is covered with the extrudate. Thus, the foamed insulating layer 2 is obtained on the inner conductor 1.

In the foamed electric wire 5, it is preferable that the melt tension at the time of rupture of the base resin in the foamed insulating layer 2 is 30 mN or more because the foamed cells can be more sufficiently miniaturized, and more preferably 45 mN or more. preferable. However, if the melt tension at the time of rupture of the base resin is too large, the degree of foaming tends to be low at the time of extruding the base resin. Therefore, the melt tension is preferably 55 mN or less, more preferably 50 mN or less. Preferably, it is 48 mN or less.

The melt tension of the base resin at the time of breaking can be adjusted by adjusting the temperature at the die outlet of the extruder, for example.

The outer diameter of the foam insulation layer 2 is preferably less than 1.5 mm and more preferably 1.0 mm or less when the foamed electric wire 5 is used for a high-frequency cable.

In the foamed electric wire 5, the foamed insulating layer 2 preferably has a foaming degree of 30 to 60%. In this case, crushing (deformation) of the transmission cable 10 can be suppressed, and even if a foamed electric wire for a transmission cable used in a high frequency band is made of a foamed insulating layer 2 using a propylene resin, the foamed cell becomes coarse. The foamed insulating layer 2 in a foamed state having fine and uniform foamed cells can be obtained. Moreover, the transmission cable 10 using the foamed electric wire 5 has a small outer diameter variation, and even if the foamed insulating layer 2 is thin, there is little problem of crushing, and variations such as deterioration of attenuation are sufficiently suppressed.

Further, it is preferable to interpose a thin layer made of unfoamed resin, so-called inner layer, between the foamed insulating layer 2 and the inner conductor 1. Thereby, the adhesiveness of the foam insulation layer 2 and the internal conductor 1 can be improved. In particular, when the unfoamed resin is made of polyethylene, the adhesion between the foamed insulating layer 2 and the internal conductor 1 can be further improved. The inner layer can also prevent deterioration (embrittlement) of the foamed insulating layer 2 due to copper in the inner conductor 1. Note that the thickness of the thin layer may be, for example, 0.01 to 0.1 mm.

Further, it is preferable to interpose a thin layer made of unfoamed resin, so-called outer layer, between the foamed insulating layer 2 and the outer conductor 3. Thereby, the adhesiveness of the foam insulation layer 2 and the external conductor 3 can be improved. In particular, when the unfoamed resin is made of polyethylene, the adhesion between the foamed insulating layer 2 and the outer conductor 3 can be further improved. In addition, since the outer layer is interposed between the foamed insulating layer 2 and the outer conductor 3, the outer diameter fluctuation is reduced, and the skew and VSWR are improved. Moreover, crush resistance improves and the outer diameter of the foamed electric wire 5 can also be made small. Note that the thickness of the thin layer may be set to 0.02 to 0.05 mm, for example.

<External conductor>
Next, the outer conductor 3 is formed so as to surround the foamed electric wire 5 obtained as described above. As the external conductor 3, a known one that has been conventionally used can be used. For example, the external conductor 3 can be formed by winding a conductive wire or a tape formed by sandwiching a conductive sheet between resin sheets along the outer periphery of the insulating layer 2. Further, the outer conductor 3 can be constituted by a corrugated metal tube, that is, a corrugated metal tube. In this case, the flexibility of the foamed electric wire 5 can be improved.

<Sheath>
Finally, the sheath 4 is formed. The sheath 4 protects the outer conductor 3 from physical or chemical damage. Examples of the material constituting the sheath 4 include resins such as fluororesin, polyethylene, and polyvinyl chloride. From the viewpoint of the above, a halogen-free material such as polyethylene resin is preferably used.

The transmission cable 10 is obtained as described above.

FIG. 3 is an end view showing a Twinax type transmission cable having the foamed electric wire 5. As shown in FIG. 3, the Twinax type transmission cable 20 is a laminate layer composed of two foamed electric wires 5, a drain wire 6, a laminate tape 7, two power lines 8, an aluminum tape layer and a braided layer. 9 and a sheath 4. Here, the two foamed electric wires 5 are arranged in parallel to each other, and these are used as signal lines. The laminate tape 7 is wound around the foamed electric wire 5 and the drain wire 6, and the sheath 4 is formed on the laminate layer 9 so as to surround the laminate layer 9. The laminate tape 7 is composed of a laminate of, for example, an aluminum foil and a polyethylene terephthalate film, and the sheath 4 is composed of, for example, an olefin-based non-halo material such as ANA 9897N manufactured by Riken Technos. The foamed electric wire 5 and the foamed insulating layer 2 are the same as those in the above embodiment.

The present invention is not limited to the above embodiment. For example, in the above embodiment, an example in which the foamed electric wire 5 is applied to a coaxial cable or a Twinax type transmission cable as a transmission cable is shown. The foamed electric wire 5 is a USB 3.0 cable, an HDMI cable, Infiniband. It can also be applied to high-speed transmission cables such as cables and micro USB cables.

Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
First, FB3312 (trade name, manufactured by Nippon Polypro Co., Ltd., hereinafter referred to as “EP1”), which is an ethylene-propylene block copolymer, was prepared as a base resin.

Then, EP1 in an extruder (product name: Laboplast Mill D2020, screw diameter (D): φ20 mm, effective screw length (L): 400 mm, manufactured by Toyo Seiki Seisakusho Co., Ltd.), copper damage inhibitor and chemical foaming shown in Table 1 The agent was added and melt-kneaded to perform extrusion molding. At this time, a copper damage inhibitor and a chemical foaming agent were added in amounts shown in Table 1 to 100 parts by mass of EP1. In Table 1, the unit of blending amount is parts by mass. At this time, the temperature of the extruder was set to 200 to 220 ° C., so that ADCA was thermally decomposed while melting the base resin.

Then, the extrudate was extruded from the extruder into a tube shape, and the twisted wire conductor in which seven copper wires having a diameter of 0.127 mm were twisted was covered with the tube-like extrudate. Thus, a foamed electric wire composed of a stranded wire conductor and a foamed insulating layer covering the stranded wire conductor was produced. At this time, the extrudate was extruded so that the foamed insulating layer had an outer diameter of 0.92 mm and a thickness of 0.3 mm.

Two foamed electric wires thus obtained were arranged in parallel, and these were wound together with a drain wire and a laminate tape having a thickness of 22 μm made of a laminate of an aluminum layer and a polyethylene terephthalate layer. Next, this was wound with an aluminum tape layer having a thickness of 25 μm together with two power lines having an outer diameter of 0.8 mm, and then covered with a braided layer, and further olefin-based non-halo material ANA9897N (trade name, manufactured by Riken Technos) Covered with a sheath consisting of In this way, a Twinax type transmission cable was produced.

(Examples 2 to 52 and Comparative Examples 1 to 11)
Type of base resin, type and amount of copper damage preventive agent, silica content, type of chemical foaming agent and amount thereof, melt tension and take-off speed when base resin breaks, transmission cable impedance, foam insulation layer A twinax type transmission cable was prepared in the same manner as in Example 1 except that the outer diameter of each and the foaming degree in the foamed insulating layer were as shown in Tables 1, 3 and 5. In Tables 1, 3, and 5, the unit of the blending amount is parts by mass.

Specific examples of the base resin, copper damage inhibitor, chemical foaming agent, and silica shown in Tables 1, 3, and 5 were as follows.
(1) Base resin (1-1) EP1
FB3312: Nippon Polypro Co., Ltd. ethylene / propylene copolymer (1-2) EP2
FB5100: Nippon Polypro Co., Ltd. ethylene / propylene copolymer (1-3) EP3
Mixture of FB3312 (40 parts by mass) and J703W (60 parts by mass) J703W: Mitsui Chemicals ethylene / propylene copolymer (1-4) EP4
Mixture of FB3312 (30 parts by mass) and B101WAT (60 parts by mass) B101WAT: Ethylene / propylene copolymer (1-5) EP5 manufactured by Mitsui Chemicals, Inc.
Mixture of FB3312 (45 parts by mass) and J703W (55 parts by mass) (1-6) EP6
Mixture of FB3312 (40 parts by mass) and B101WAT (60 parts by mass) (1-7) EP8
FB3312 (70 parts by mass) and B101WAT (30 parts by mass) mixture (1-8) PP1
Mixture of J105G (70 parts by mass) and VP103 (30 parts by mass) J105G, VP103: Homopolypropylene (1-9) PP2 manufactured by Mitsui Chemicals, Inc.
A mixture of J105G (80 parts by mass) and VP103 (20 parts by mass) (1-10) PP3
Mixture of J105G (40 parts by mass) and VP103 (60 parts by mass) (1-11) [EP + PE]
Mixture of FB3312 (80 parts by mass) and Ultozex 4020L (20 parts by mass) Ultozex 4020L: Polyethylene (2) copper damage inhibitor (2-1) CDA1 manufactured by Prime Polymer Co., Ltd.
ADK STAB CDA-1 (Adeka Co., Ltd. copper damage inhibitor, 3- (N-salicyloyl) amino-1,2,4-triazole)
(2-2) CDA6
ADK STAB CDA-6 (Adeka Co., Ltd. copper damage inhibitor, decamethylenedicarboxylic acid disalicyloyl hydrazide)
(2-3) MD1024
Irganox MD1024 (a copper damage inhibitor, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide, manufactured by Ciba Specialty Chemicals)
(3) Chemical foaming agent (3-1) ADCA
Azodicarbonamide (3-2) baking soda FE-507 (Ewa Kasei Kogyo Co., Ltd. foaming agent Cellbon series)
(4) Silica Carplex # 80 (Shionogi Pharmaceutical Silica)

[Characteristic evaluation]
The following characteristics of the foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11 were evaluated.

(1) Melt tension and take-off speed at break The melt tension and take-off speed at break were measured for the foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11 as follows.

That is, melt tension and take-up speed were measured using a capillary rheometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Specifically, the melt tension and the take-up speed were measured as follows. First, a base resin was filled into a flat capillary having an inner diameter of 1.0 mm and a length of 10 mm. Thereafter, in the capillary rheometer, the piston speed was set to 5 mm / min, the barrel inner diameter was set to 9.55 mm, the take-up acceleration was set to 400 m / min ² , and the temperatures of the barrel, the capillary, and the thermostat immediately after the barrel were set to 200 ° C. Then, the base resin was filled in the barrel, and after 5 minutes preheating, piston extrusion was started at the above piston speed. And the tension | tensile_strength and take-up speed | velocity | rate when the base resin was accelerated by the said take-up acceleration, and were fractured | ruptured were measured. The average value of the measured values of tension and take-up speed obtained by performing this measurement 10 times was calculated. The results are shown in Tables 1, 3, and 5.

(2) Degree of foaming The degree of foaming is the following formula:

Calculated based on The results are shown in Tables 1, 3, and 5. Here, “resin before foaming” refers to a base resin before being charged into an extruder.

(3) Average foamed cell diameter and standard deviation A part of the foam insulation layer was cut out from the foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11, and the cross section of the foam insulation layer was measured with a scanning electron microscope. The cell diameter for each of the 100 foam cells that were observed and randomly selected was:

Measured based on And while calculating the average value of the cell diameter of 100 foam cells as "average foam cell diameter", the standard deviation of the cell diameter of the foam cell was computed. The results are shown in Tables 2, 4 and 6. In Tables 2, 4, and 6, a foamed electric wire having a foamed insulating layer having an average foamed cell diameter of less than 50 μm and a standard deviation of less than 25 μm is regarded as acceptable, and a foamed wire having other foamed insulating layers is regarded as rejected. did.

(4) Outer diameter fluctuation range For the 500 m long foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11, the maximum and minimum values of the outer diameter were measured using an outer diameter measuring instrument (high speed and high speed manufactured by Keyence Corporation). Using a precision digital measuring instrument LS-7000 series)

Was used to calculate the outer diameter fluctuation range. The results are shown in Tables 2, 4 and 6.

(5) Skew The transmission cables obtained in Examples 1 to 52 and Comparative Examples 1 to 11 were cut, and 10 2 m transmission cables were prepared. And about these 10 transmission cables, the skew was measured using TDR TDS8000 (brand name, Nippon Tektronix Co., Ltd. product), and the average value was computed. The results are shown in Tables 2, 4 and 6.

(6) Attenuation amount With respect to the transmission cables obtained in Examples 1 to 52 and Comparative Examples 1 to 11, using a network analyzer (manufactured by 8722ES Agilent Technologies), a frequency signal of 1.25 GHz and a signal of 2.5 GHz The attenuation was measured for each of the above. Next, these transmission cables were left in an atmosphere of 85 ° C. and 90% RH for 1000 hours, and then the signal attenuation was measured in the same manner as before. The ratio of the attenuation amount of the signal after being left to the attenuation amount of the signal before being left is expressed by the following formula:

Calculated based on The results are shown in Tables 2, 4 and 6.

(7) Side pressure deformation rate The foamed insulating layers obtained in Examples 1 to 52 and Comparative Examples 1 to 11 were cut into a length of 3 cm to prepare test pieces. Then, after placing a test piece on a cylindrical jig having a diameter of 8.5 mm and a length of 5.0 mm and preheating for 30 minutes, a load was applied to the test piece using a testing machine, and the outer diameter after 30 minutes was determined. It was measured. And the following formula:

Based on the above, the lateral pressure deformation rate was calculated. The results are shown in Tables 2, 4 and 6. The outer diameter of the foamed insulating layer was measured at 20 ° C. and 100 ° C., and the load was 2 kg at 20 ° C. and 1 kg at 100 ° C. Further, as a testing machine, a heating deformation testing machine of “three-piece heating deformation testing machine model number W-3” manufactured by Toyo Seiki Seisakusho Co., Ltd. was used.

(8) Thermal aging deterioration The foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11 were put in a thermostatic bath and taken out every month. Then, it was wound around a mandrel having a diameter of 3 mm at room temperature to examine whether or not a crack would occur. The results are shown in Tables 2, 4 and 6. In addition, if heat aging deterioration was 2.5 years or more, it was set as the pass.

(9) Bending characteristics The bending characteristics were evaluated by conducting a bending test on the transmission cables obtained in Examples 1 to 52 and Comparative Examples 1 to 11. The bending test was carried out by repeatedly bending using a bending tester and examining the number of times until breakage. Specifically, a 200 g weight was attached to one end of the transmission cable using a bending tester. And the transmission cable was hung perpendicularly | vertically using the location of 800 mm from the end of the transmission cable which attached this weight. Then, the other end of the transmission cable was reciprocated so as to draw a semicircular arc around the fulcrum, and the bending test was performed by bending 90 degrees left and right around the fulcrum. The results are shown in Tables 2, 4 and 6. In Tables 2, 4, and 6, the bending characteristics of Examples 1 to 52 and Comparative Examples 1 to 11 are indicated by any one of A to C based on the following criteria.

A: When damaged when the number of bending is 10,000 times or more B: When damaged when the number of bending times is 5000 or more and less than 10,000 C C: When damaged when the number of bending times is less than 5000

(10) Adhesiveness of Foamed Insulating Layer to Internal Conductor The adhesiveness of the foamed insulating layer to the internal conductor in the foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11 was evaluated based on the results of the following tests. That is, first, the foamed electric wires obtained in Examples 1 to 52 and Comparative Examples 1 to 11 were cut to a length of 10 cm, and both ends of the inner conductor were pierced so that 5 cm remained in the middle. Then, using a strograph made by Toyo Seiki Seisakusho Co., Ltd., one end of the inner conductor was fixed with one chuck, the foamed insulating layer was fixed with the other chuck, and pulled at a take-up speed of 100 mm / min. And the force when a foaming insulating layer began to move was measured. The results are shown in Tables 2, 4 and 6. In Tables 2, 4, and 6, the adhesion of the foamed insulating layer to the inner conductors of Examples 1 to 52 and Comparative Examples 1 to 11 is indicated by any one of A to C based on the following criteria.

A: The force when the foamed insulating layer starts to move is 1.5 kg weight or more. B ... The force when the foamed insulating layer starts to move is 0.5 kg weight or more and less than 1.5 kg weight. The force when the insulation layer starts to move is less than 0.5kg weight

(11) Discharge rate reduction rate The resin composition was continuously fed into an extruder (product name: Laboplast mill D2020, screw diameter (D): φ20 mm, effective screw length (L): 400 mm, manufactured by Toyo Seiki Seisakusho). Then, the extrusion molding is continued, and the discharge amount of the extrudate after 10 hours has elapsed after being charged into the extruder (hereinafter referred to as “initial discharge amount”), and the discharge amount of the extrudate after another one hour has passed. From the following formula, the rate of decrease in the discharge amount of the extrudate is:

Calculated based on The results are shown in Tables 2, 4 and 6. In Tables 2, 4, and 6, the discharge rate reduction rates of Examples 1 to 52 and Comparative Examples 1 to 11 are indicated by any one of A to D based on the following criteria.

A ... Reduction rate is less than 0.2% B ... Reduction rate is 0.2% or more and less than 0.5% C ... Reduction rate is 0.5% or more and less than 1.0% D ... Reduction rate is 1.0% or more

From the results shown in Tables 1 to 6, Examples 1 to 52 and Comparative Examples 1 to 11 were over 2.5 years in terms of heat aging deterioration, and passed the acceptance criteria. The foamed electric wires of Examples 1 to 52 had a foamed insulating layer having an average foamed cell diameter of less than 50 μm and a standard deviation of less than 25 μm, and all of them reached the acceptance standard. In contrast, the foamed electric wires of Comparative Examples 1 to 11 have a foam insulation layer with an average cell diameter of 50 μm and a standard deviation of 25 μm, and both the average foam cell diameter and the standard deviation have reached the acceptance criteria. There wasn't.

Therefore, according to the foamed electric wire of the present invention, it was confirmed that a sufficiently fine foamed cell can be obtained and can be continuously used for a long time even in a high temperature environment.

DESCRIPTION OF SYMBOLS 1 ... Internal conductor (conductor), 2 ... Foam insulation layer, 5 ... Foam electric wire, 10, 20 ... Transmission cable.

Claims

Conductors,
A foamed electric wire comprising a foamed insulating layer covering the conductor,
The foam insulation layer is
A base resin containing a propylene-based resin, having a melt tension at break of 20 to 55 mN and a take-up speed of 50 m / min or more;
Chemical foaming agents,
Obtained by melt-kneading a resin composition containing a copper damage inhibitor,
The chemical blowing agent is azodicarbonamide;
The copper damage inhibitor is 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl. ] At least one selected from the group consisting of propionohydrazide and decamethylenedicarboxylic acid disalicyloyl hydrazide;
Foamed wire characterized by
The foamed electric wire according to claim 1, wherein the resin composition further contains silica particles.
3. The foamed electric wire according to claim 1 or 2, wherein the base resin has a melt tension of 20 to 48 mN at break.
The foamed electric wire according to any one of claims 1 to 3, wherein the foamed insulating layer has a foaming degree of 30 to 60%.
The foamed electric wire according to any one of claims 1 to 4, wherein an inner layer made of an unfoamed resin is provided between the foamed insulating layer and the conductor.
The foamed electric wire according to any one of claims 1 to 5, wherein an outer diameter of the foamed insulating layer is less than 1.5 mm.
A transmission cable having the foamed electric wire according to any one of claims 1 to 6.