JP2009099315A - Coaxial cable and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable and a manufacturing method for a coaxial cable capable of obtaining a smooth outer cover surface by preventing the invasion of bubbles into an outer cover of the coaxial cable. <P>SOLUTION: The coaxial cable 10 comprises a center conductor 11, an internal insulator 12 arranged at the outer periphery of the center conductor 11, an external conductor 13 arranged at the outer periphery of the internal insulator 12, and the outer cover 14 arranged at the outer periphery of the external conductor. A polymer liquid layer 16 with a thickness of a designated range is arranged between the outer cover 14 formed of UV-curing type resin and the external conductor 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coaxial cable having a jacket of an ultraviolet curable resin and a method for manufacturing the same.

  Ultrafine coaxial cables are used in a wide range of applications such as medical devices such as ultrasonic diagnostic devices and endoscope devices, electronic devices such as notebook computers, and communication devices such as mobile phones. In general, this coaxial cable has a structure in which a central conductor is covered with an insulator, a plurality of conductor wires are horizontally wound around the insulator to form an outer conductor, and the outer conductor is covered with a jacket. (For example, refer to Patent Documents 1 to 3).

  In the coaxial cable described in Patent Document 1, an insulating coating is formed around the central conductor to form an insulating layer, and an insulating coating such as an ultraviolet curable resin is applied to the outside of the outer conductor to form a jacket. is doing. Moreover, in the coaxial cable described in Patent Document 2, an outer cover is formed by applying an ultraviolet curable resin to the outside of the outer conductor.

  Further, in the coaxial cable described in Patent Document 3, an insulating layer is provided outside the core wire (center conductor), a shield layer (outer conductor) is provided outside the insulating layer, and the surface of the shield layer is roughened. It is described that an ultraviolet curable resin can be used as a protective resin layer on the outer side of the copper oxide coating layer.

JP-A-62-143314 JP 2002-352642 A Japanese Patent Laid-Open No. 5-81938

  By the way, when forming the jacket of the ultraviolet curable resin, the shield core (the one formed with the central conductor, the inner insulator, and the outer conductor) is passed through a die filled with the ultraviolet curable resin composition. After the ultraviolet curable resin composition is applied, it is cured by irradiation with ultraviolet rays. At that time, when the outer conductor formed by being twisted around the outer periphery of the inner insulator enters the ultraviolet curable resin composition of the die, the air bubbles are likely to be engulfed by the unevenness of the surface, and the air bubbles easily enter the resin. These bubbles are cracked before the UV curable resin composition is cured, and a crater-like recess is formed on the outer surface of the outer cover, and the substantial thickness of the outer cover is reduced in the recess. The characteristics will deteriorate.

  Accordingly, an object of the present invention is to provide a coaxial cable and a method for manufacturing the coaxial cable, which can prevent bubbles from entering the jacket and obtain a smooth jacket surface.

The coaxial cable capable of solving the above-described problems is a center conductor, an inner insulator disposed on the outer periphery of the center conductor, an outer conductor disposed on the outer periphery of the inner insulator, and the outer conductor. A coaxial cable having a jacket disposed on the outside,
The outer cover is formed of an ultraviolet curable resin, and a polymer liquid layer is provided between the outer cover and the outer conductor,
In the cross section orthogonal to the axis of the coaxial cable, the radius of the circle inscribed by the outer conductor is s (μm), the radius of the outer peripheral surface of the jacket is R (μm), and the radius of the outer peripheral surface of the polymer liquid layer Is A (μm), s + α <A ≦ R−5 (μm),
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: An integer obtained by rounding down the decimals.

The manufacturing method of the coaxial cable according to the present invention that can solve the above-described problems includes a center conductor, an inner insulator disposed on the outer periphery of the center conductor, and an outer member disposed on the outer periphery of the inner insulator. A method of manufacturing a coaxial cable having a conductor and a jacket disposed outside the outer conductor,
Providing an inner insulator on the outer periphery of the central conductor;
An outer conductor is provided on the outer periphery of the inner insulator to form a shield core,
When a polymer liquid layer is formed by applying a polymer liquid to the outer periphery of the shield core, the radius of the circle inscribed by the outer conductor is s (μm) in the cross section orthogonal to the axis of the coaxial cable, When the radius of the outer peripheral surface of the jacket is R (μm) and the radius of the outer peripheral surface of the polymer liquid layer is A (μm), s + α <A ≦ R−5 (μm),
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: After forming the polymer liquid layer to be an integer rounded down to the nearest decimal point,
The outer covering of the polymer liquid layer is coated with an ultraviolet curable resin and cured to form the outer cover.

  According to the present invention, since the polymer liquid layer is provided with a thickness within a predetermined range between the outer conductor and the outer sheath made of the ultraviolet curable resin, the irregularities on the outer peripheral surface of the outer conductor are made to be a polymer liquid. After filling with a layer and smoothing, an ultraviolet curable resin can be applied to form a jacket. For this reason, when applying UV curable resin, it is possible to prevent bubbles from entering the resin, prevent the surface of the outer cover from forming irregularities due to bubbles, and improve the withstand voltage characteristics. it can.

Hereinafter, an example of an embodiment of a coaxial cable and a method for manufacturing the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a coaxial cable according to the present embodiment, and FIG. 2 is a schematic view showing radii and the like of respective portions in the coaxial cable.

  As shown in FIG. 1, the coaxial cable 10 according to this embodiment includes a center conductor 11, an inner insulator 12 disposed on the outer periphery of the center conductor 11, and an outer periphery of the inner insulator 12. It has an outer conductor 13 and a jacket 14 disposed outside the outer conductor. The coaxial cable 10 is an extremely fine coaxial cable having a diameter of 0.35 mm or less, and is a wire thinner than No. 40 by AWG (American Wiring Gauge).

  The coaxial cable 10 has a center conductor 11 at the center in the radial cross section. The central conductor 11 is formed to have a diameter of about 0.09 mm or less by twisting together a plurality of conductor wires 11 a (here, for example, seven) having a diameter of about 0.03 mm or less. The central conductor may be composed of a single conductor wire.

  An inner insulator 12 is provided on the outer periphery of the center conductor 11. The thickness of the internal insulator 12 is approximately 0.05 mm, and the diameter to the outer peripheral surface of the internal insulator 12 is approximately 0.25 mm or less. The outer periphery of the inner insulator 12 is covered with an outer conductor 13 formed by laterally winding a plurality (for example, 21 in this case) of conductor wires 13a having a diameter of approximately 0.03 mm. The diameter to the outer peripheral surface of the outer conductor 13 is approximately 0.31 mm or less. Furthermore, the outer side of the layer of the outer conductor 13 is covered with a jacket 14 made of an ultraviolet curable resin.

  As the ultraviolet curable resin for forming the outer cover 14, for example, urethane acrylate resin, urethane acrylate resin blended with epoxy acrylate resin or polyester acrylate resin, or the like can be used.

  Here, in general, when the outer sheath 14 made of an ultraviolet curable resin is formed on the outside of the outer conductor 13 by a die, a shield core (the core conductor 11, the inner insulator 12, and the outer conductor 13 are formed) When 15 is put into the resin interface in the die, the resin interface is greatly disturbed by the irregularities on the outer peripheral surface of the layer of the outer conductor 13, and bubbles may be generated. The bubbles at this time adhere to the irregularities on the surface of the shield core 15 and become bubbles in the outer jacket 14. Further, when the shield core 15 enters the resin of the die, the resin enters the gap between the conductor wire 13a of the outer conductor 13 and the inner insulator 12, and the air existing in the gap is between the conductor wires 13a. It is pushed out to the outside and becomes air bubbles and comes out on the surface, and becomes air bubbles in the jacket 14.

  For this reason, in the coaxial cable 10 of this embodiment, the polymer liquid layer 16 is provided between the jacket 14 and the outer conductor 13, and the unevenness on the outer surface of the outer conductor 13 is smoothed by the polymer liquid layer 16 (cross section). The outer circumference of the outer conductor 13 is rounded), and the gap between the outer conductor 13 and the inner insulator 12 is filled, or the resin does not soak into the gap. At this time, the outer surface of the layer of the outer conductor 13 may be smoothed by the polymer liquid layer 16 without completely filling the gap.

As shown in FIG. 2, the polymer liquid layer 16 has a radius to the outer surface of the outer conductor 13 in a cross section orthogonal to the axis of the coaxial cable 10 (the radius of a circle in which the outer conductor 13 is inscribed, that is, a shield core). 15 (radius of 15) is s (μm), the radius to the outer peripheral surface of the jacket 14 (that is, the radius of the coaxial cable 10) is R (μm), and the radius of the outer peripheral surface of the polymer liquid layer 16 is A (μm). , S + α <A ≦ R−5 (μm).
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: An integer rounded down to the nearest decimal point.

  Here, α is a safe amount considering the penetration of the polymer liquid into the gap between the outer conductor 13 and the inner insulator 12. Usually, the polymer liquid soaks at the moment when the shield core 15 enters the polymer liquid coating die, but at the portion where the outer conductor 13 is tightly twisted, the speed of soaking is slow and it takes time until immediately before the application of the UV curable resin. It is expected that there will be. Considering such a place, if the polymer liquid layer 16 having a thickness of α (μm) is coated in advance in addition to the radius s of the minimum shield core 15, the unevenness of the outer conductor 13 over the entire length is made of polymer. It is coated with a liquid and smoothed.

  That is, if the thickness A of the polymer liquid layer 16 is less than s + α (μm), the effect of smoothing the surface unevenness cannot be obtained, the bubble suppression effect is lost, bubbles appear, and the yield decreases. Since it is considered, A> s + α. On the other hand, when the thickness A of the polymer liquid layer 16 is R-5 (μm) or more, the thickness of the jacket 14 is 5 (μm) or less, and the stress applied to the jacket 14 during a bending test or a torsion test. Since the thickness of the outer cover 14 increases and cracks and tears occur, A ≦ R−5 (μm) is set from the viewpoint of ensuring a minimum thickness of the outer cover of 5 (μm).

  As the polymer liquid, for example, a liquid such as grease or wax that is softened / liquefied by heating and solidified or increased in viscosity when cooled, or a gelled liquid can be used. The grease may be applied only to the surface of the shield core 15 to smooth the unevenness, or may be immersed in a heated and melted liquid so as to fill the inside of the external conductor 13. As the grease, for example, general type I grease manufactured by Chukyo Kasei Co., Ltd., Lubriace, Bearlex, Superlex, etc. can be used.

As the polymer liquid, silicone oil, a surfactant, a soldering flux, or the like can be used. Among them, it is preferable to use silicone oil because it hardly swells with respect to the ultraviolet curable resin and has stable characteristics over a long period of time.
As the silicone oil, one having a high molecular weight and a small number of modifying groups is preferable in order to prevent the transition to the outer jacket 14. Particularly, those having an average molecular weight of about 4000 to 10,000 are suitable.

  A suitable oil for the polymer liquid is KF96 manufactured by Shin-Etsu Chemical Co., and dimethyl silicone oil having a viscosity of about 1 to 10,000 cps can be exemplified. Alternatively, modified silicone may be used.

Moreover, it is preferable to use what has reactivity as a polymer liquid. When the polymer liquid is reactive, energy can be applied to the polymer liquid to cause gelation, which has the advantage of improving long-term stability.
As the polymer liquid having such reactivity, for example, a mixture of a photopolymerization initiator that generates radicals when irradiated with ultraviolet rays and reactive silicone can be used. When this mixture is applied on the outer conductor and then irradiated with ultraviolet rays, the reactive silicone is polymerized into a gel.
Further, a mixture of silicone oil and platinum can be used as the reactive polymer liquid. In this case, the polymer liquid can be gelled by heating.
Examples of the silicone gel suitable as the polymer liquid include GE Toshiba Silicone TSE3053, TSE3070, TSE3081 and the like.

  According to such a coaxial cable, since the polymer liquid layer 16 is provided in a predetermined range of thickness between the outer sheath 14 made of an ultraviolet curable resin and the outer conductor 13, the outer periphery of the outer conductor 13 Surface irregularities can be smoothed with a polymer liquid to prevent air bubbles from entering the outer cover 14, so that a thin portion of the outer cover 14 is not formed, and the thickness is substantially uniform in the circumferential direction. Therefore, the withstand voltage characteristics are good.

Next, an example of an embodiment of a method for manufacturing a coaxial cable according to the present invention will be described.
FIG. 3 is a schematic configuration diagram illustrating an example of a coating forming apparatus used in the method of manufacturing a coaxial cable according to the present embodiment.
As shown in FIG. 3, in this coating forming apparatus 20, an inner insulator 12 is provided outside the center conductor 11, and a shield core 15 having an outer conductor 13 formed outside the inner insulator 12 is wound up. A supply bobbin 21 is provided. On the downstream side of the supply bobbin 21, a polymer liquid application die 23 for applying the polymer liquid 16 a to the outside of the external conductor 13 via the guide roller 22, and an ultraviolet curable resin composition for forming the jacket 14. An outer die 24 for applying 14a is provided. As the polymer liquid coating die 23, a first-layer die used for forming a two-layer coating in an optical fiber coating apparatus can be used. Alternatively, an open die can be used. Alternatively, the polymer liquid may be applied as a pass line through which the shield core 15 passes through the storage tank storing the polymer liquid without using a die. Further, a pinhole for adjusting the diameter of the polymer liquid layer may be provided between the two dies 23 and 24 so as to adjust to a desired outer diameter. If a pin hole is used, it is easier to pass even if the hole diameter is smaller than that of a die, and workability is good.

  3 shows the case where the polymer liquid application die 23 and the outer cover die 24 are provided apart from each other, they may be applied in a dual manner. In the dual method, two dies are arranged in series without gaps, and the polymer liquid 16a and the ultraviolet curable resin composition 14a are applied almost simultaneously.

As the ultraviolet curable resin composition 14a, for example, a resin composition such as a urethane acrylate resin or a urethane acrylate resin blended with an epoxy acrylate resin or a polyester acrylate resin can be used.
Specifically, as a monomer or oligomer, urethane acrylate obtained by reacting bisphenol A / ethylene oxide addition diol, tolylene diisocyanate and hydroxyethyl acrylate; polytetramethylene glycol, tolylene diisocyanate and hydroxyethyl acrylate are reacted. Urethane acrylate obtained; oligomer and tricyclodecane diacrylate selected from urethane acrylate obtained by reacting tolylene diisocyanate and hydroxyethyl acrylate; N-vinylpyrrolidone; isibonyl acrylate; bisphenol A / ethylene oxide addition diol di Acrylate; lauryl acrylate; bisphenol A apoxy acrylate; ethylene oxide addition It can be used a nil phenol acrylate. These monomers may be used independently and may be used in combination of 2 or more type.

Examples of the photopolymerization initiator used for the ultraviolet curable resin composition 14a include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6-trimethyl. Examples thereof include benzoyldiphenylphosphine oxide. The content of the photopolymerization initiator is preferably 0.5% by weight to 5.0% by weight with respect to the resin composition.
In addition, various additives can be mix | blended with the ultraviolet curable resin composition 14a as needed.

  Further, an ultraviolet irradiation device 25 having, for example, an ultraviolet lamp for irradiating ultraviolet rays to cure the ultraviolet curable resin composition 14 a is provided on the downstream side of the outer cover die 24. A guide roller 26, a take-up device 27, and a take-up device 28 are sequentially provided on the downstream side.

The method for manufacturing the coaxial cable according to the present embodiment is a method for manufacturing the coaxial cable 10 described above. First, the inner insulator 12 is provided on the outer periphery of the center conductor 11, and the outer conductor 13 is provided on the outer periphery of the inner insulator 12. The shield core 15 is formed. The shield core 15 is supplied from the supply bobbin 21 to the polymer liquid application die 23, and the polymer liquid 16a is coated on the outside of the outer conductor 13 with a predetermined thickness to form the polymer liquid layer 16. The outer surface of the shield core 15 is smoothed. At this time, in the cross section orthogonal to the axis of the shield core 15, the radius to the outer peripheral surface of the outer conductor 13 is s (μm), the radius of the outer peripheral surface of the outer sheath 14 is R (μm), and the outer periphery of the polymer liquid layer 16 When the radius of the surface is A (μm), the polymer liquid layer 16 is provided so that s + α <A ≦ R−5 (μm).
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: Integer rounded down

  The shield core 15 on which the polymer liquid layer 16 is formed is supplied to the jacket die 24 and the ultraviolet curable resin composition 14a is applied thereto. The shield core 15 to which the ultraviolet curable resin composition 14a has been applied is sent to the ultraviolet irradiation device 25 where it is cured by being irradiated with ultraviolet rays, whereby an ultraviolet curable resin envelope 14 is formed. Thereby, the coaxial cable 10 is manufactured. After the direction of the pass line is changed by the guide roller 26, the coaxial cable 10 is taken up by the take-up device 27 and taken up by the take-up device 28.

  According to the method for manufacturing a coaxial cable described above, the polymer liquid layer 16 is provided in a predetermined range of thickness between the outer sheath 14 made of an ultraviolet curable resin and the outer conductor 13. The unevenness of the 13 outer peripheral surfaces can be filled and smoothed. Along with this, it is possible to prevent bubbles from entering the jacket 14 when the jacket 14 is formed, and to improve the withstand voltage characteristics of the coaxial cable 10.

  In the above embodiment, as a method of applying the polymer liquid 16a, the case of so-called on-line application in which the application is performed on the same line before the outer die 24 for applying the ultraviolet curable resin composition 14a has been described. Alternatively, the polymer resin 16a may be applied off-line in a separate process.

In the case of off-line application, the shield core 15 previously dipped or applied in a polymer liquid is applied with the UV curable resin composition 14a as the outer cover 14 using a normal outer cover forming apparatus. To do. Further, the polymer liquid 16a is applied in advance to the conductor wire 13a, and the conductor wire 13a is twisted to form the outer conductor 13, or the polymer liquid is previously applied to the outer peripheral surface of the inner insulator 12. The external conductor 13 can be formed by applying 16a and twisting the conductor wire 13a to the internal insulator 12. The subsequent formation of the jacket 14 may be performed on the same line as the twisting step of the conductor wire 13a or may be performed on a separate line. It should be noted that when the shield core 15 coated with the polymer liquid 16a is fed out, the polymer liquid 16a needs to have a viscosity that does not fly. For this purpose, the polymer liquid 16a preferably has a high viscosity such as grease or wax. Further, it is preferable to pass the shield core 15 coated with the polymer liquid 16a through a die, a pinhole or the like to remove the excessively adhered polymer liquid 16a.
Also by such an offline process, the smoothed shield core 15 can be obtained in the same manner as online.

It is sectional drawing which shows the example of embodiment of the coaxial cable which concerns on this invention. It is explanatory drawing which shows the radius etc. of each site | part of the coaxial cable of FIG. It is a schematic block diagram which shows an example of the coating | coated formation apparatus used for the manufacturing method of the coaxial cable which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Coaxial cable 11 Center conductor 12 Inner insulator 13 Outer conductor 13a Conductor strand 14 Outer sheath 14a Ultraviolet curable resin composition 16 Polymer liquid layer 16a Polymer liquid

Claims (2)

A coaxial having a center conductor, an inner insulator disposed on the outer periphery of the center conductor, an outer conductor disposed on the outer periphery of the inner insulator, and a jacket disposed on the outer side of the outer conductor A cable,
The outer cover is formed of an ultraviolet curable resin, and a polymer liquid layer is provided between the outer cover and the outer conductor,
In the cross section orthogonal to the axis of the coaxial cable, the radius of the circle inscribed by the outer conductor is s (μm), the radius of the outer peripheral surface of the jacket is R (μm), and the radius of the outer peripheral surface of the polymer liquid layer Is A (μm), s + α <A ≦ R−5 (μm),
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: Coaxial cable characterized by being an integer rounded down to the nearest decimal point. A coaxial having a center conductor, an inner insulator disposed on the outer periphery of the center conductor, an outer conductor disposed on the outer periphery of the inner insulator, and a jacket disposed on the outer side of the outer conductor A cable manufacturing method comprising:
Providing an inner insulator on the outer periphery of the central conductor;
An outer conductor is provided on the outer periphery of the inner insulator to form a shield core,
When a polymer liquid layer is formed by applying a polymer liquid to the outer periphery of the shield core, the radius of the circle inscribed by the outer conductor is s (μm) in the cross section orthogonal to the axis of the coaxial cable, When the radius of the outer peripheral surface of the jacket is R (μm) and the radius of the outer peripheral surface of the polymer liquid layer is A (μm), s + α <A ≦ R−5 (μm),
However,
α (μm) = √ (r ′ ² −l ^2. <πr ′ / l> / 2 + 4rl + 4l ² ) − (r + 2l)
r (μm): radius of internal insulator 80 ≦ r ≦ 125
R (μm): 125 ≦ R ≦ 175
l (μm): radius of the cross section of the conductor wire constituting the outer conductor r ′: r + l
<>: After forming the polymer liquid layer to be an integer rounded down to the nearest decimal point,
A method of manufacturing a coaxial cable, wherein an outer periphery of the polymer liquid layer is coated with an ultraviolet curable resin and cured to form the jacket.

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