WO2004107005A1

WO2004107005A1 - Optical fiber cable producing method, and optical fiber cable

Info

Publication number: WO2004107005A1
Application number: PCT/JP2004/007652
Authority: WO
Inventors: Yoshitaka Matsuyama; Hitoshi Tsuchiya
Original assignee: Asahi Glass Company, Limited
Priority date: 2003-05-27
Filing date: 2004-05-27
Publication date: 2004-12-09
Also published as: JP4320660B2; TW200500676A; JPWO2004107005A1

Abstract

An optical fiber cable producing method capable of molding a jacket tube at higher temperatures without increasing transmission loss. In an optical fiber cable producing method for extrusion-molding a jacket tube on the outer periphery of a plastic optical fiber through a gap or another material by an extrusion molding device, immediately before the plastic optical fiber is introduced into the extrusion molding device, it is cooled by a cooling device.

Description

Manufacturing method of optical fiber cable, and optical fiber cable

The present invention relates to a method for manufacturing an optical fiber cable in which a plastic optical fiber is housed in a jacket tube, and an optical fiber cable obtained by the method. Background art

The optical fiber used as a large-capacity communication medium is a silica glass optical fiber.

(Silica glass fiber) and plastic optical fiber (hereinafter sometimes abbreviated as “P〇F”). Among them, POF has a larger core diameter than quartz glass optical fiber and is excellent in workability such as terminal processing, so its various applications are expanding. In particular, a graded-index plastic optical fiber (hereinafter abbreviated as “GI-POF” by Babai) that has a distribution of the refractive index in the cross-sectional direction has a high-speed, large-capacity transmission capability, and is used in next-generation communications. It is expected as an optical fiber.

The bare optical fiber (bare fiber) is not practical, and it is not practical, and it is necessary to protect the optical fiber, increase the number of cores, attach connectors, and so on. It is used as an optical fiber cable by being compounded with a tensile strength material such as wire or a fiber tensile strength material such as aramid fiber.

The method of manufacturing this optical fiber cable basically consists of extruding the outer periphery of the outer tube with a thermoplastic resin, etc., together with a constituent material such as a tensile member (tension member) that resists the POF against pulling, and covering and forming the sheath tube. It is done by doing. During the coating molding, the POF is easily affected by the heat of a thermoplastic resin or the like melted at a high temperature, and the heat may reduce the physical properties of the POF.

In the above GI_POF, low molecular compound materials with different refractive indices are contained in the resin material There is a method of forming a GI-POF by thermally diffusing a material to form a refractive index distribution. In particular, in such GI-POF, low-molecular compound materials undergo thermal diffusion in the GI-PF under the influence of heat during coating molding into a cable, and the refractive index distribution changes, resulting in transmission loss. May increase. For this reason, when converting GI-POF into a cable, it is necessary to manufacture the cable so that it is not affected by heat. As an optical fiber cable that solves the above problems, for example, WO01 / 95002 pamphlet includes a plurality of GI-POFs and a resin cable body including the GI-POF. An optical fiber cable having the resin cable main body, wherein the resin cable main body has the same number of the GI-POFs as the number of void holes penetrating in the longitudinal direction, and the GI-POF freely moves in the void holes. An optical fiber cable is disclosed, which is movable and dispersed one by one.

In the above-mentioned optical fiber cable of International Publication No. 0 950 002, since the jacket tube has a void penetrating in the longitudinal direction, heat transmitted to the POF is blocked by the void. This makes it less susceptible to the heat.

According to this optical fiber cable, if the melting temperature of the jacket tube is 135 or less, it is possible to prevent an increase in transmission loss due to thermal effects, and therefore, a typical coating resin is a soft vinyl chloride resin-polyethylene resin. If there is, you can usually use it.

However, in addition to the transmission characteristics described above, optical fiber cables are required to have further flame retardancy. Such flame retardancy is usually achieved by adding a flame retardant to the jacket tube. However, the melting temperature of the resin generally increases in accordance with the content of the flame retardant. For example, even in the case of the above-mentioned soft pinyl chloride resin or polyethylene resin, the melting temperature may rise to 140 ° C. or more depending on the amount of the flame retardant added. Therefore, when a resin having higher flame retardancy is used as the jacket tube, it is necessary to mold the jacket tube at a molding temperature exceeding 140 ° C.

However, in the above-mentioned conventional technology, heat resistance is insufficient because the heat is blocked only by the voids. As a result, the transmission loss of P〇F increases. For this reason, the molding temperature of the outer tube is limited, and as a result, the type of resin that can be used as the outer tube is limited, and there is a problem that a highly flame-resistant outer tube cannot be used. In this case, it is conceivable to increase the above-mentioned voids to enhance the heat blocking effect. However, as a result, there is a problem that the outer diameter of the cable becomes large.

Therefore, an object of the present invention is to form a jacket tube at a higher temperature without increasing transmission loss, and as a result, a resin having excellent flame retardancy can be used as the jacket tube. Another object of the present invention is to provide a method for manufacturing a small-diameter optical fiber cable. Disclosure of the invention

In order to achieve the above object, a method of manufacturing an optical fiber cable according to the present invention is directed to a method of manufacturing an optical fiber cable in which an outer tube is extruded and formed around a plastic optical fiber through a gap or another material. The plastic optical fiber is cooled and introduced into an extruder. In the present invention, cooling is preferably performed immediately before introduction into the extrusion molding apparatus.

ADVANTAGE OF THE INVENTION According to the manufacturing method of the optical fiber cable of this invention, the influence of the heat to POF can be reduced significantly by cooling before introducing POF into an extrusion-molding apparatus. Therefore, it is possible to form the jacket tube at a higher temperature without increasing transmission loss, and it is possible to use a resin having excellent flame retardancy as the jacket tube. Preferably, the cooling temperature is 5 or less. By setting the cooling temperature of the POF at 5 ° C. or less, the influence of heat on the POF can be significantly reduced.

Further, in the present invention, it is preferable that the optical fiber cable has no spacer. This is because the present invention is suitable for manufacturing an optical fiber cable having no spacer. In the present invention, the outer diameter of the optical fiber cable is preferably 7 mm or less. This is because the present invention is suitable for manufacturing an optical fiber cable having such a small outer diameter.

In the present invention, it is preferable that the optical fiber cable formed by covering the jacket tube with the extrusion molding device is forcibly cooled immediately after being taken out of the extrusion molding device. According to this, since the cooling is performed immediately after the jacket tube is formed, the cooling effect of P〇F is further enhanced, and an increase in transmission loss at the time of forming at a high temperature can be further prevented.

In the present invention, it is preferable that the other material is a fiber tensile strength member. According to this, since the fiber strength member itself has heat insulating properties, it is possible to further prevent an increase in transmission loss during molding at a high temperature.

Further, in the present invention, it is preferable that the outer tube contains a flame retardant and is made of a thermoplastic resin having a melting temperature of 140 to 190 ° C. According to this, a resin having excellent flame retardancy can be used as the jacket tube, and the flame retardancy of the optical fiber cable can be improved.

On the other hand, the optical fiber cable of the present invention is an optical fiber cable obtained by the above manufacturing method, wherein the flame retardancy of the resin used for the sheath tube of the optical fiber cable is specified by JISK7201. It has a characteristic oxygen index of 29 or more. According to this, an optical fiber cable having excellent flame retardancy can be obtained, so that high flame retardancy is required, such as vertical trunk lines of buildings and condominiums, horizontal wiring on each floor, floor wiring, and the like. It can be suitably used for applications. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing one embodiment of an optical fiber cable obtained by the manufacturing method of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an embodiment of an apparatus for manufacturing an optical fiber cable used in the manufacturing method of the present invention. FIG. 3 is a perspective view of the cooling device.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a partial perspective view showing the vicinity of a nozzle of the extrusion molding apparatus.

FIG. 6 is a sectional view showing another embodiment of the optical fiber cable obtained by the manufacturing method of the present invention.

FIG. 7 is a schematic configuration diagram showing another embodiment of the optical fiber cable manufacturing apparatus used in the manufacturing method of the present invention.

10, 11: Optical fiber cable,

20: POF (plastic optical fiber), 21, 31, 61: reel,

22, 32: hole, 30: strength member, 40: void,

50, 51: Jacket tube, 60: Fiber tensile strength member, 62: Fiber bundle,

121, 122, 123, 140, 150, 161, 162, 163: Guide roller,

300: Cooling device, 310: Box, 311: Lid, 312: Pipe,

313: Insulation material, 320: Dry ice,

400: extrusion molding equipment, 410: nozzle, 420: protrusion,

430: flat part, 440: core, 450: outer cylinder,

500: cooling water tank, 600: take-up machine, 610, 620: belt, 611, 612, 621, 622: pulley. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows an embodiment of an optical fiber cable obtained by the manufacturing method of the present invention.

The optical fiber cable 10 has two POFs 20 arranged in the center, two strength members 30 respectively arranged outside the POF 20, and an outer periphery of the POF 20 surrounded by a gap 40. To cover the outer periphery of the tensile strength member 30 An outer tube 50 is provided.

Here, to cover the outer periphery of the POF 20 so as to surround the outer periphery of the POF 20 via the gap 40 means that the inner surface of the outer cover tube 50 and the outer periphery of the POF 20 are the length of the optical fiber cable. This means that at least part or all of the cross section perpendicular to the direction (the cross section shown in Fig. 1) is non-contact. In addition, "the inner surface of the outer tube 50 and the outer periphery of the P〇F 20 are" at least partially non-contact (not entirely non-contact) "means one or more points on the outer periphery of the POF 20. Means that it is in contact with the inner surface of the jacket tube 50. In other words, at least a part of the space 40 between the POF 20 and the jacket tube 50 is interposed. Here, the POFs 20 are distributed and arranged one by one in a freely movable state inside the jacket tube 50.

The material of POF 20 is not particularly limited, and a fluororesin, a polymethylmethacrylate (PMMA) resin, or the like can be used. Above all, it is preferable to use a fluororesin, especially a transparent fluororesin, since transmission loss is low and a usable wavelength range of light is wide. As the fluororesin POF, for example, those described in JP-A-8-55848 or the like are preferably used. The outer diameter of POF20 is preferably from 400 to 100 x m.

As the strength member 30, for example, a metal wire such as a zinc plated hard steel wire, a copper alloy, and stainless steel, or a fiber reinforced plastic obtained by solidifying aramide fiber, glass fiber, or the like with a resin is preferably used.

As the jacket tube 50, an extrudable thermoplastic resin such as a soft vinyl chloride resin and a polyethylene resin can be used. As described above, in the present invention, since the jacket tube 50 can be molded at a higher temperature, a thermoplastic resin having a melting temperature of 140 to 190 is preferably used. Particularly, in the case where the optical fiber cable does not have the fiber tensile strength member of the outer periphery of the POF and the outer tube, that is, at least a gap is formed between the inner surface of the outer tube covering the POF and the outer periphery of the P 0 F. In the case where the thermoplastic resin is interposed and the fiber tensile strength member is not interposed, the melting temperature of the thermoplastic resin is preferably 140 to 170 ° C. Also, as described later, When the fiber tension member is provided between the outer circumference of the POF and the inner surface of the outer tube, at least a part between the inner surface of the outer tube covering the POF and the outer circumference of the In the case of non-contact (separated) and a configuration in which the fiber tensile strength member is arranged between the inner surface of the outer tube and the outer periphery of the POF, the melting temperature of the above thermoplastic resin is 1 65 ~ 190 ° C is preferred. Examples of such a resin include a so-called flame-retardant grade resin obtained by adding a flame retardant to a thermoplastic resin such as the above-mentioned soft vinyl chloride resin or polyethylene resin.

This optical fiber cable 10 preferably does not have a spacer. However, the spacer is a spacer such as a slotted spacer. These spacers can also function as insulation. That is, when manufacturing an optical fiber cable having a spacer, there is little restriction on the material of the jacket tube. Conversely, in the case of an optical fiber cable having no spacer, it is preferable to apply the manufacturing method of the present invention in that the restriction on the material (molding temperature) of the jacket tube can be eliminated. Has an outer diameter (diameter) of preferably 7 mm or less, particularly preferably 2 to 5 mm. This is because, in the production of these small-diameter cables, the effect of heat at the time of molding the jacket tube on the POF is large, and thus the effect of applying the production method of the present invention is large. Preferably, these small diameter cables have one to six cores.

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

2 to 5 show an apparatus for manufacturing the optical fiber cable 10 described above. 2 is a schematic configuration diagram showing the entire manufacturing apparatus, FIG. 3 is a perspective view of the cooling apparatus, FIG. 4 is a cross-sectional view taken along the line B-B of FIG. 3, and FIG. 5 shows the vicinity of the nozzle of the extrusion apparatus. It is a partial perspective view.

In FIG. 2, reference numeral 21 denotes a POF take-up reel. The two POFs 20 fed from the reel 21 are guided by guide rollers 14 0 and 15 2 through guide rollers 12 1, 12 2 and 12 3, respectively. Introduced in 300 ing.

Reference numeral 31 denotes a payout reel for the tensile strength member 30. The two strength members 30 drawn out from the reel 31 are also guided by the guide rollers 140 and 150, respectively. As a result, as shown in FIGS. 3 and 4, a total of four of the two central POFs 20 and the tensile strength members 30 on both sides are brought into alignment and introduced into the cooling device 300. ′ A cooling device 300 is provided in front of the guide roller 150 (in the traveling direction of the POF 200). As shown in FIGS. 3 and 4, the cooling device 300 has a box 310, a lid 3111, and a pipe 312 penetrating the box 310. The inside of the box 310 and the outer periphery of the pipe 312 are filled with dry ice 3200. A heat insulating material 3 13 is attached to the inner wall of the box 3 12.

The two aligned POFs 20 and the two strength members 30 are passed through the inside of the pipe 312. In this case, two POFs 20 and two strength members 30 are appropriately stretched so as not to contact the inner wall of the pipe 312.

In addition, as the material of the box 310, metals such as stainless steel and aluminum, and resins such as polyethylene and polypropylene are preferably used. As the material of the pipe 312, copper, brass, stainless steel or the like is preferably used. Urethane foam, styrene foam or the like is preferably used as the heat insulating material 3 13.

The cooling device 300 is adjusted so that the surface temperature (cooling temperature) of the POF 20 derived therefrom is preferably 5 ° C or lower, more preferably 110 ° C or lower. Although there is no particular lower limit for the cooling temperature, it is preferably −80 ° C. or higher from the viewpoint of easy handling of P〇F. This cooling can significantly reduce the effect of heat on the POF 20 and prevent an increase in transmission loss. However, the surface temperature of the POF can be measured by bringing a thermocouple into contact with the surface of the POF. In this case, it is preferable that the thermometer and the POF are covered together with a heat insulating material.

The cooling means of the cooling device 300 is not limited to the dry ice described above, but surrounds the pipe 312. In addition, a structure in which a cooling medium flows through a cooling pipe for cooling, a structure in which a pair of cooling plates cooled by a Peltier element or the like are passed, and the like can be adopted. In addition, a contact-type cooling means such as a cooling roller can be employed.

In addition, in the next step of covering the jacket tube 50, the tensile strength member 300 only needs to be disposed outside the POF 20 and does not necessarily need to pass through the cooling device 300.

An extruder 400 for extruding the jacket tube 50 is provided at the outlet of the cooling device 300. It is preferable that the cooling device 300 and the extrusion device 400 are arranged as close as possible. That is, the POF 200 is preferably cooled just before being introduced into the extrusion molding apparatus 400. This is to prevent the POF 20 cooled by passing through the cooling device 300 from warming up. Specifically, the cooling temperature of P〇F 20 in the POF introduction portion of the nozzle 410 of the extrusion apparatus 400 is preferably 5 or less, more preferably 110 ° C. or less. Is adjusted to Therefore, the passage time of POF 20 from the outlet of the cooling device 300 to the POF introduction portion of the nozzle 410 (from the outlet of the cooling device 300 to the POF introduction portion of the nozzle 410). The value obtained by dividing the distance by the feeding speed of POF 20) is preferably 2 seconds or less, and particularly preferably 1 second or less.

As shown in FIG. 5, the nozzle 4100 of the extrusion molding apparatus 400 has two projections 4200 having a hole 22 through which the POF 20 passes. A core 4400 comprising a flat portion 4340 having holes 32 through which the tensile strength members 30 are inserted and disposed on both sides, and a predetermined gap is further provided on the outer periphery of the core 4400. And an outer cylinder 450 arranged.

The POF 20 is passed through the hole 22, and the tensile strength member 30 is inserted through the hole 32, and the outside is inserted between the core 44 and the outer cylinder 450. The thermoplastic resin forming the covered tube 50 is extruded into a spectacle shape in a molten state to form the covered tube 50. At this time, since the heat of the molten thermoplastic resin is not directly transmitted to the POF 20 by the voids 40 generated by the projections 420, the POF 20 Since the cooling is performed by the initial cooling device 300, the synergistic effect of the two can prevent the POF 20 from deteriorating due to heat and prevent an increase in transmission loss.

A cooling water tank 500 is provided further ahead of the extrusion molding apparatus 400. The optical fiber cable 10 formed by covering the jacket tube 50 passes through the water in the cooling water tank 500. By passing the optical fiber cable 10 through the water in the cooling water tank 500, the jacket tube 50 just formed is rapidly cooled, preventing heat from being transmitted to the POF 20 inside, and transmission. Prevent loss increase.

Further behind the cooling water tank 500, a take-off device 600 is arranged. The take-up machine 600 is stretched over a pair of pulleys 6 11 and 6 12 and rotates, and the take-up machine 6 0 0 is stretched over a pair of pulleys 6 2 1 and 6 2 2 to rotate. It has a lower belt 62 and has a structure in which the optical fiber cable 10 is sandwiched between the belts 6 10 and 6 20 and fed out. The optical fiber cable 10 thus formed is wound and stored on a winding reel (not shown).

The optical fiber cable 10 obtained by the above-described manufacturing method can greatly reduce the influence of heat on POF20. Therefore, the jacket tube 50 can be molded at a higher temperature without increasing transmission loss, and a resin having excellent flame retardancy can be used as the jacket tube 50. As a result, the flame retardancy of the optical fiber cable 10 can be improved.

The flame retardancy of the resin used for this jacket tube is represented by the oxygen index (L〇I%) specified by JISK7201. According to the production method of the present invention, it is possible to produce an optical fiber cable 10 having a jacket tube 50 using a resin having an oxygen index of 29 or more.

FIG. 6 shows another embodiment of the optical fiber cable obtained by the manufacturing method of the present invention. FIG. 7 shows an apparatus for manufacturing the optical fiber cable. In the following description of the embodiment, the same parts as those of the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, the optical fiber cable 11 has a fiber The fiber tensile strength member 60 is surrounded by a tensile strength member 60, and the outer periphery of the fiber tensile strength member 60 is further covered with a jacket tube 51. As described above, by interposing (intervening) the fiber strength member 60 between the POF 20 and the jacket tube 50, the heat insulating property of the fiber strength member itself is utilized, and the sheath tube 5 at a high temperature is used. It is possible to further prevent an increase in transmission loss during molding of 1.

As the fiber tensile strength member 60, for example, fibers such as aramide fiber, polyethylene terephthalate (PET) fiber, carbon fiber, and glass fiber can be used. Above all, it is preferable to use aramide fiber from the viewpoint of rigidity, flexibility, and prevention of fiber breakage due to repeated bending.

As shown in FIG. 7, the apparatus for manufacturing the optical fiber cable 11 includes a reel 21 that feeds out one POF 20 and a reel 61 that feeds out four fiber strength members 60. This is different from the manufacturing apparatus in FIG.

With this manufacturing apparatus, the fiber bundle 62 of the fiber tensile strength material unwound from the reel 61 is guided by guide rollers 161, 162, and 163, and is drawn out onto the manufacturing line. The fiber bundle 62 is inserted into the extruder 400 in a state of being arranged in four directions so as to surround the POF 20. When the filament of each fiber bundle is unraveled in the nozzle 410 and exits from the nozzle 410, the outer periphery of the POF 20 is annularly surrounded to form a fiber tensile strength member 60 as shown in FIG. .

(Example)

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

'Example 1

An optical fiber cable having the structure shown in FIG. 1 was manufactured using the apparatus shown in FIG. P〇F 20 is a fluororesin POF (manufactured by Asahi Glass Co., Ltd., trade name: Lucina) manufactured by the method described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-55848, and has an outer diameter of 0.5. mm.

The cooling device 300 is a copper pipe with an inner diameter of 8 mm and a length of 30 cm as the pipe 3 1 2 The cooling was performed under the conditions of a linear velocity of P〇F 10 of 15 mZ and a residence time of 1.2 seconds, and the surface temperature of the POF 20 derived from the cooling device 300 was adjusted to 110. The distance from the outlet of the cooling device 300 to the inlet of the nozzle 410 of the extrusion device 400 was 10 cm.

Flame-retardant polyethylene (trade name: SNE 9932N: manufactured by RIKEN TECHNOS) is used as the jacket tube 50, the melting temperature is 160 ° C, the outer diameter of the jacket tube 50 is 3.5X6.4mm, and the gap 40 is 1.2X. It was molded to be 1.2 mm.

The cooling condition in the cooling bath 500 was set to −10 ° C. using an ethylene glycol aqueous solution.

Comparative Example 1

In the first embodiment, the optical fiber cable was used under the same conditions as in the first embodiment except that the cooling in the cooling device 300 was not performed and the surface temperature of the P〇F 20 derived from the cooling device 300 was set to 20. Was manufactured.

Comparative Example 2

An optical fiber cable was manufactured under the same conditions as in Comparative Example 1 except that a flame-retardant soft vinyl chloride resin (trade name: SHV9861N: manufactured by Riken Technos) was used as the jacket tube 50 and the melting temperature was 135.

Test example 1

The loss increase (dBZkm) and oxygen index (LOI%) of the optical fiber cables of Example 1 and Comparative Example 12 were measured. The loss increase was measured by the cutback method specified in JIS C-6823, and the oxygen index was measured by the method specified in JIS K7201. The results are shown in Table 1.

(table 1)

From the results in Table 1, in Example 1, the melting temperature at 160 Even when molded at a predetermined temperature, there was no increase in loss, and an optical fiber cable excellent in flame retardancy as compared with Comparative Example 2 was obtained. On the other hand, in Comparative Example 1 in which the cooling step was not performed, the loss increased.

Example 2

The optical fiber cable having the structure shown in FIG. 6 was manufactured by the apparatus shown in FIG. 7 using the same POF 20 and cooling device 300 as those used in Example 1, and the cooling conditions of the cooling device 300 were also the same as in Example 1. I made it. Aramide fiber (1270 decitex, using four fibers) was used as the fiber tensile strength member 60.

Using a flame-retardant polyolefin (trade name: ANA9952N: manufactured by Ligen Technos Co.) as the jacket tube 51, at a melting temperature of 180, the thickness of the jacket tube 50 should be 0.5 mm and the outer diameter should be 2.6 mm. Molded.

Comparative Example 3

In the second embodiment, an optical fiber cable was used under the same conditions as in the second embodiment, except that the cooling in the cooling device 300 was not performed, and the surface temperature of the POF 20 derived from the cooling device 300 was 20 ° C. Was manufactured.

Comparative Example 4

An optical fiber cable was manufactured under the same conditions as in Comparative Example 3, except that a flame-retardant soft vinyl chloride resin (trade name: SHV9861N: manufactured by Riken Technos Co., Ltd.) was used as the jacket tube 51 and the melting temperature was 160 ° C. ,

Test example 2

For the optical fiber cables of Example 2 and Comparative Example 34, the loss increase (dBZkm) and oxygen index (L〇I%) were measured in the same manner as in Test Example 1. The results are shown in Table 2.

(Table 2)

Optical fiber Resin melting loss increase Cooling process for jacket tube

Cooling temperature nc) Temperature C) (dB / km) Resin oxygen index) Example 2 Yes-10 180 0 45 Comparative example 3 20 180 + 20 45 Comparative example 4 5 £ 20 160 0 28 According to the results in Table 2, in Example 2, even when the outer tube 51 was molded at a melting temperature of 180 ° C, there was no increase in loss, and the flame retardancy was superior to that of Comparative Example 4. An optical fiber cable was obtained. On the other hand, in Comparative Example 3 in which the cooling step was not performed, the loss increased. Industrial potential

As described above, according to the present invention, the influence of heat on the POF can be significantly reduced by cooling the POF immediately before introducing it into the extrusion molding apparatus. Therefore, it is possible to mold the jacket tube at a higher temperature without increasing transmission loss, and it is possible to select a flame-retardant resin as the jacket tube, which is superior in flame retardancy. An optical fiber cable can be provided.

Claims

The scope of the claims

1. A method of manufacturing an optical fiber cable in which a jacket tube is extruded through an air gap or another material around a plastic optical fiber, wherein the plastic optical fiber is cooled and introduced into an extruder. A method of manufacturing an optical fiber cable.

2. The method of manufacturing an optical fiber cable according to claim 1, wherein a cooling temperature of the plastic optical fiber is 5 ° C or less.

3. The optical fiber cable according to claim 1 or 2, wherein the optical fiber cable formed by covering the outer tube with the extrusion molding device is forcibly cooled immediately after being taken out of the extrusion molding device. Manufacturing method.

4. The method of manufacturing an optical fiber cable according to claim 1, wherein the other material is a fiber tensile strength member.

5. The method of manufacturing an optical fiber cable according to any one of claims 1 to 4, wherein the optical fiber cable has no spacer.

6. The method of manufacturing an optical fiber cable according to claim 1, wherein an outer diameter of the optical fiber cable is 7 mm or less.

7. The optical fiber cable according to any one of claims 1 to 6, wherein the outer tube contains a flame retardant and is made of a thermoplastic resin having a melting temperature of 140 to 190 ° C. Manufacturing method.

8. An optical fiber cable obtained by the manufacturing method according to claim 7, wherein the flame retardancy of the resin used for the sheath tube of the optical fiber cable is 2 in terms of an oxygen index defined by JISK7201. An optical fiber cable characterized by being 9 or more.