JP5552293B2 - Foamed electric wire and transmission cable having the same - Google Patents

Description

  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. It has been proposed to stably and reliably form a foamed insulating layer having a high foaming degree by using a compound obtained by adding a chemical foaming agent such as azodicarbonamide and a filler such as silica to the coalescence ( 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 foamed cell in the foamed insulating 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.

  Moreover, since silica is contained when kneading the base resin and the chemical foaming agent, the extrusion amount of the extrudate decreases with time, so that the production efficiency of the foamed electric wire decreases. As a result, the price of the foamed electric wire is increased.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a foamed electric wire capable of obtaining a sufficiently fine foamed cell and capable of reducing the price, and a transmission cable having the foamed electric wire.

  In order to solve the above-mentioned 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, by adding not only a chemical foaming agent but also a predetermined amount of silica to a base resin containing a propylene-based resin, the foamed cell can be sufficiently miniaturized, and thereby attenuated. It became clear that the amount was also suppressed. Further, it was considered that the addition of the predetermined amount of silica can suppress the sticking of the base resin to the screw of the extruder and can smoothly knead the base resin with the chemical foaming agent. 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-based resin, has a melt tension at break of 20 to 55 mN, and a take-off speed. Is obtained by melt-kneading a resin composition containing a base resin having a viscosity of 50 m / min or more and 200 m / min or less , a chemical foaming agent, silica particles, and a copper damage inhibitor, and the chemical foaming agent is azodicarboxylic It is an amide, the silica particles are blended at a ratio of 0.03 to 1 part by mass with respect to 100 parts by mass of the base resin, and the copper damage inhibitor is 0.25 to 1 with respect to 100 parts by mass of the base resin. It is a foamed electric wire characterized by being mix | blended in the ratio of the mass part .

According to this foamed electric wire, a sufficiently fine foam cell can be obtained by including silica in the resin composition containing the base resin and the chemical foaming agent. Moreover, it can fully suppress that the extrusion amount of an extrudate falls with time. For this reason, the manufacturing efficiency of a foamed electric wire improves. As a result, the price of the foamed electric wire can be reduced. Moreover, according to the foamed electric wire of this invention, the deterioration by heat aging is fully suppressed as the addition amount of a copper harm prevention agent exists in the said range, and the lifetime of a foamed electric wire can be lengthened more.

  Moreover, this invention is a transmission cable which has the said foamed electric wire. According to this transmission cable, a sufficiently fine foam cell can be obtained and the price can be reduced, so that a transmission cable with reduced attenuation can be obtained and the price of the transmission cable can be reduced. It becomes.

In the present invention, “melt tension at break” is a melt tension measured using a capillary rheometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.), and specifically, an inner diameter of 1.0 mm and a length of 10 mm. The base capillary is filled with a base resin, the piston speed is 5 mm / min, the barrel inner diameter is 9.55 mm, the take-up acceleration is 400 m / min ² , and the temperature of the barrel, capillary and the thermostat immediately after the barrel is set to 200 ° C. It was obtained by filling the barrel with the base resin, starting the piston extrusion at the above piston speed after 5 minutes preheating, accelerating at the above take-up acceleration, taking out, measuring the tension when it was broken, and performing this 10 times. The average value of the measured values of tension shall be said.

  ADVANTAGE OF THE INVENTION According to this invention, the foamed electric wire which can obtain a sufficiently fine foam cell and can be reduced in price, and a transmission cable which has this are provided.

It is a partial side view which shows one Embodiment of the transmission cable of this invention. It is sectional drawing along the II-II line of 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 cross-sectional view taken along the 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 foamed insulating layer 2 contains a propylene-based resin, a resin containing a base resin having a melt tension at break of 20 mN to 55 mN and a take-up speed of 50 m / min, a chemical foaming agent, and silica particles. It is obtained by melt-kneading the composition. Here, azodicarbonamide is used as the chemical foaming agent, and the silica particles are added at a ratio of 0.03 parts by mass to 1 part by mass with respect to 100 parts by mass of the base resin.

  According to the foamed electric wire 5 having such a configuration, a sufficiently fine foam cell can be obtained by including silica in the resin composition containing the base resin and the chemical foaming agent, and Lower prices are also possible. Therefore, according to the transmission cable 10 having the foamed electric wire 5, it is possible to obtain the transmission cable 10 in which the attenuation amount is suppressed and to reduce the price of the transmission cable 10.

  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 foamed insulating layer 2, a base resin, a chemical foaming agent, and silica particles are prepared.

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

  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 and 2-hexene. Among these, α-olefins such as ethylene, 1-butene, and 1-hexene are preferably used from the viewpoint of realizing more sufficient refinement 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-based resin preferably has a melting point of 150 ° C. or higher. Here, when the melting point is less than 150 ° C., the heat resistance of the foamed electric wire 5 is significantly reduced. 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 less because the balance between the heat resistance and the low temperature embrittlement resistance and the bending resistance can be kept good.

  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.

  The take-up speed at the time of breaking the base resin is 50 m / min or more, preferably 80 m / min or more, and 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 mass, more preferably 0.5 to 0.7 part by mass, with respect to 100 parts by mass 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.

(Silica particles)
Even if the resin composition is continuously melt-kneaded for a long time, the silica particles can sufficiently suppress the decrease in the discharge amount, and the production efficiency of the foamed electric wire 5 can be improved. Here, the addition amount of the silica particles is 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, a decrease in the discharge amount from the extruder can be sufficiently suppressed, so that the production efficiency of the foamed electric wire 5 is improved and the price of the foamed electric wire 5 can be reduced. In addition, an increase in attenuation due to the hygroscopic property of silica can be sufficiently suppressed.

(Copper damage prevention agent)
It is preferable that a copper damage inhibitor is added to the base resin. 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 these, 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide is used. This is preferable because finer foam cells can be obtained.

  In addition, when the copper damage inhibitor was used with the silica particle, it was thought that it promoted the coarsening of a foam cell. However, the silica particles are the above-mentioned specific copper damage inhibitor, namely 3- (N-salicyloyl) amino-1,2,4-triazole, 2 ′, 3-bis [3- (3,5-di-tert-butyl). When combined with -4-hydroxyphenyl) propionyl] propionohydrazide or decamethylenedicarboxylic acid disalicyloyl hydrazide, coarsening of the foamed cells is suppressed, and the silica particles prevent copper damage other than the specific copper damage inhibitor. It has been clarified by the inventor's research that, when combined with an agent, the foamed cells tend to be coarsened.

  The copper damage inhibitor is preferably added in an amount of 0.01 to 1 part by weight, preferably 0.1 to 1 part by weight, more preferably 0.25 to 0.5 part by weight, based on 100 parts by weight of the base resin. Added. 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.

  When the above base resin, chemical foaming agent and silica particles are put into an extruder and the resin composition in the extruder is melt-kneaded, the chemical foaming agent is first uniformly dispersed in the base resin, and then chemical foaming is performed. The agent is heated to a temperature equal to or higher than its thermal decomposition temperature and thermally decomposed to generate 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, the melt tension at the time of rupture of the base resin in the foamed insulating layer 2 is preferably 30 mN or more, because the foamed cells can be more sufficiently miniaturized, and is preferably 45 mN or more. Is more preferable. However, if the melt tension at the time of rupture of the 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. 48 mN or less is more preferable.

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

  When the foamed electric wire 10 is used for a high frequency cable, the outer diameter of the foamed insulating layer 2 is preferably less than 1.5 mm, and more preferably 1.0 mm or less.

(Antioxidant)
In addition, it is preferable to add antioxidant to the said 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 addition amount of the antioxidant with respect 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, 2 , 6-di-tert-butyl-α-dimethylamino-p-cresol, 2,4,6-tri-tert-butylphenol, o-tert-butylphenol and other monophenols, 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-di-second -Polyphenols such as 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 Hindered phenols such as tributyl-4-hydroxy-5-methylphenyl) propionyloxy} -1, dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] -undecane, 4,4 ′ -Thiobis- (6-tert-butyl-3-methylphenol), 4,4'-thiobis- (6-tert-butyl-o-cresol), bis (3,5-di-tert-butyl- 4-hydroxybenzyl) sulfides, thiobisphenols such as dialkyl / phenol / sulfide, phosphites, phosphorous tris such as tris (2,4-di-tert-butylphenyl) phosphite Nonylphenyl), dilauryl thiodipropionate, distearyl thiodipropionate, distearyl-β, β-thiodibutyrate, lauryl stearyl thiodipropionate, dimyristyl-3,3′-thiodipropionate , Ditridecyl-3,3′-thiodipropionate, sulfur-containing ester compounds, amyl-thioglycolate, 1,1′-thiobis- (2-naphthol), 2-mercaptobenzimidazole, hydrazine derivatives, and the like. . These can be used alone or in combination of two or more.

  In the foamed electric wire 5, it is preferable that the foam insulation layer 2 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 propylene-based resin is used for the foam insulating layer 2 as a foamed electric wire for a transmission cable used in a high frequency band, the foamed cell becomes coarse. It is possible to obtain a foamed insulating layer 2 in a foamed state having fine and uniform foamed cells. 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.

  Moreover, it is preferable to interpose a thin layer made of unfoamed resin, a 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. The thickness of the thin layer may be 0.01 to 0.1 mm, for example.

  Furthermore, it is preferable to interpose a thin layer made of unfoamed resin, a 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 internal conductor 1 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, the skew and VSWR are improved, the crush resistance is improved, and the outer diameter of the foamed electric wire 5 is improved. Can also be reduced. In addition, what is necessary is just to let the thickness of a thin layer be 0.02-0.05 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 a cross-sectional 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 comprising two foamed electric wires 5, a drain wire 6, a laminate tape 7, two power lines 8, an aluminum tape layer, and a knitted coarse layer. A layer 9 and a sheath 4 are provided. 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 content 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.

( Reference 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.

  And EP1, silica, and the chemical foaming agent shown in Table 1 are put into an extruder (product name: Labo Plast Mill D2020, screw diameter (D): φ20 mm, effective screw length (L): 400 mm, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Then, it was melt-kneaded and extruded. At this time, silica and a chemical foaming agent were added in amounts shown in Table 1 with respect to 100 parts by mass of EP1. At this time, by setting the temperature of the extruder to 200 to 220 ° C., ADCA was thermally decomposed while melting the base resin.

  And the extrudate was extruded from the extruder in the shape of a tube, and the twisted wire conductor which twisted seven copper wires with a diameter of 0.127 mm was covered with this tube-shaped 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 outer diameter of the foamed insulating layer was 0.92 mm and the thickness was 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.

( Reference Examples 2 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6)
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 Reference 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 addition, the following were specifically used as the base resin, copper damage inhibitor, chemical foaming agent, and silica shown in Tables 1, 3, and 5.
(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 (1-12) PE1 manufactured by Prime Polymer
Hizex 5305E: High-density 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
ADEKA STAB CDA-6 (Adeka Co., Ltd. copper damage inhibitor, decamethylenedicarboxylic acid disali tyrosyl hydrazide)
(2-3) MD1024
Irganox MD1024 (Ciba Specialty Chemicals copper damage inhibitor, 2 ',
3-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide)
(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 were evaluated for the foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6.

(1) Melt tension and take-off speed at break
Regarding the foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6, the melt tension at break was measured as follows.

That is, the melt tension was measured using a capillary rheometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Internal diameter 1.0mm in particular, the base resin was filled in flat capillary length 10 mm, the piston speed 5 mm / min, a barrel inner diameter 9.55 mm, pulling acceleration 400 meters / min ^2, a barrel, a thermostat respectively immediately after the capillaries and barrel After setting the temperature of 200 ° C to 200 ° C, the base resin is filled into the barrel, and after 5 minutes preheating, piston extrusion is started at the above piston speed, and accelerated by the above take-up acceleration and taken up. The speed was measured, and 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.

に基づいて算出した。結果を表１，３，５に示す。ここで、「発泡前の樹脂」とは、押出機に投入する前のベース樹脂のことを言う。 (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.

に基づいて測定した。そして、１００個の発泡セルのセル径の平均値を「平均発泡セル径」として算出するとともに、発泡セルのセル径の標準偏差を算出した。結果を表２，４，６に示す。なお、表２，４，６において、平均発泡セル径が５０μｍ未満で、標準偏差が２５μｍ未満の発泡絶縁層を有する発泡電線を合格とし、それ以外の発泡絶縁層を有する発泡電線を不合格とした。
(3) Average foam cell diameter and standard deviation
A part of the foam insulation layer was cut out from the foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6, and the foam insulation layers The cross section was observed using a scanning electron microscope, and the cell diameter for each of 100 randomly selected foam cells was expressed by the following formula:

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.

により外径変動幅を算出した。結果を表２，４，６に示す。
(4) Outer diameter fluctuation range
About the 500 m long foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40 and Comparative Examples 1 to 6, the maximum value and the minimum value of the outer diameter are set. , Measured using an outer diameter measuring instrument (high-speed high-precision digital measuring instrument LS-7000 series manufactured by Keyence Corporation), and the following formula:

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 Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40 and Comparative Examples 1 to 6 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.

に基づいて算出した。結果を表２，４，６に示す。
(6) Attenuation amount
About the transmission cables obtained in Reference Examples 1-15, Examples 13-15, Examples 18-20, Examples 22-40 and Comparative Examples 1-6, using a network analyzer (manufactured by 8722ES Agilent Technologies), The attenuation was measured for each of cases where the frequency was 1.25 GHz and 2.5 GHz. Next, after leaving these transmission cables in an atmosphere of 85 ° C. and 90% RH for 1000 hours, the attenuation was measured in the same manner as before. Then, the ratio of the attenuation amount after being left to the attenuation amount before being left is expressed by the following formula:

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

に基づいて、側圧変形率を算出した。結果を表２，４，６に示す。なお、発泡絶縁層の外径の測定は、２０℃及び１２０℃のそれぞれの温度下で行い、荷重は２０℃のときは２ｋｇ、１２０℃のときは１ｋｇとした。また試験機としては、東洋精機製作所株式会社製の「三個掛加熱変形試験機型番Ｗ−３」の加熱変形試験機を用いた。
(7) Side pressure deformation rate
The foamed insulating layers obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6 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 120 ° C., and the load was 2 kg at 20 ° C. and 1 kg at 120 ° C. 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) Heat aging degradation
The foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6 were put into a thermostat 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 Bending characteristics were tested for the transmission cables obtained in Reference Examples 1-15, Examples 13-15, Examples 18-20, Examples 22-40 and Comparative Examples 1-6. Evaluated by doing. The bending test was carried out by repeatedly bending using a bending tester and examining the number of times until breakage. Specifically, with a bending tester, a 200 g weight is attached to one end of the transmission cable, the transmission cable is hung vertically from one end of the transmission cable with the weight as a fulcrum, and the other end of the transmission cable is A bending test was conducted by reciprocating the fulcrum around the fulcrum so as to draw a semicircular arc, and bending it 90 degrees left and right around the fulcrum. The results are shown in Tables 2, 4 and 6. In Tables 2, 4, and 6, A to C and x are based on the following criteria, respectively.

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) Adhesion of foam insulation layer to internal conductor
The adhesion of the foamed insulating layer to the internal conductor in the foamed wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40 and Comparative Examples 1 to 6 was as follows. The result was evaluated. That is, first, the foamed electric wires obtained in Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6 were cut to a length of 10 cm so that 5 cm remained in the middle. Both ends of the inner conductor were opened. 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, A, B, and x are based on the following criteria, respectively.

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

に基づいて算出した。結果を表２，４，６に示す。なお、表２，４，６において、Ａ〜Ｃ及び×はそれぞれ以下の基準に基づくものであり、「×」は不合格とし、「Ａ〜Ｃ」は合格とした。

Ａ・・・減少率が０．２％未満
Ｂ・・・減少率が０．２％以上０．５％未満
Ｃ・・・減少率が０．５％以上１．０％未満
×・・・減少率が１．０％以上

(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, A to C and x are based on the following criteria, respectively, “x” is rejected, and “A to C” is passed.

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% x ... Reduction rate is 1.0% or more

From the results shown in Tables 1 to 6, for the rate of decrease in the discharge amount, all of Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, Examples 22 to 40, and Comparative Examples 1 to 6 are “A”. "Or" B ", and the acceptance criteria were reached. Moreover, the foamed electric wires of Reference Examples 1 to 15, Examples 13 to 15, Examples 18 to 20, and Examples 22 to 40 have a foamed insulating layer having an average foamed cell diameter of less than 50 μm and a standard deviation of less than 25 μm. The foamed electric wires of Comparative Examples 1 to 6 have a foam insulation layer having an average cell diameter of 50 μm or 60 μm and a standard deviation of 25 μm or 40 μm, and the average foaming. Neither the cell diameter nor the standard deviation reached the acceptance criteria.

Therefore, according to the foamed electric wire of this invention, it was confirmed that a sufficiently fine foam cell can be obtained. In addition, all of Reference Examples 1-15, Examples 13-15, Examples 18-20, and Examples 22-40 were "A" or "B", and have reached the pass standard. Therefore, according to the present invention, it is considered that the production efficiency is improved. For this reason, it is considered possible to reduce the price by improving the production efficiency.

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

Claims (6)

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 to 200 m / min;
Chemical foaming agents,
Silica particles;
Obtained by melt-kneading a resin composition containing a copper damage inhibitor,
The chemical blowing agent is azodicarbonamide;
The silica particles are blended at a ratio of 0.03 to 1 part by mass with respect to 100 parts by mass of the base resin,
The copper damage inhibitor is blended at a ratio of 0.25 to 1 part by mass with respect to 100 parts by mass of the base resin,
Foamed wire characterized by The foamed electric wire according to claim 1, wherein the base resin has a melt tension of 20 to 38 mN at break.   The foamed electric wire according to claim 1 or 2, 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 3, 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 4, wherein an outer diameter of the foamed insulating layer is less than 1.5 mm.   The transmission cable which has a foamed electric wire as described in any one of Claims 1-5.

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