JPH0664943A - Production of core wire of optical fiber tape - Google Patents

Abstract

PURPOSE:To suppress the formation of an air void in the core wire of an optical fiber tape caused by increase in the viscosity of the resin liquid in coating. CONSTITUTION:A plurality of optical fiber elements 17 are introduced into a coating die 25 and a resin liquid is applied by the coating die 25 to collectively coat the elements. In the above process, the resin liquid is heated before introducing the optical fiber elements 17 into the coating die 25 in order to control the viscosity of the liquid to 100-2,000cps immediately before contacting the liquid with the optical fiber elements. An optical fiber tape core wire having stable loss characteristics can be produced by this process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical fiber ribbon, which is a tape-shaped combination of a plurality of optical fiber strands.

[0002]

2. Description of the Related Art Conventionally, in order to store optical fiber strands in a cable at an extremely high density, a plurality of optical fiber ribbons, which are formed by integrating a plurality of optical fiber strands into a tape, are laminated in a multilayer structure. A method of collecting a plurality of laminated bodies and covering them to form a cable is used. An outline of a method of manufacturing an optical fiber ribbon used for such an application is to prepare a plurality of optical fiber strands 1 ... In a wound state as shown in FIG. Send by 2 ... Then, the optical fiber strands 1 ... Are fed into the coating die 5 in a state of being arranged in parallel and in a line. This coating die 5
, A resin liquid having a viscosity of 100 to 2000 cps for continuously coating the optical fiber strands 1 ... Is continuously supplied from the resin supply pot 6. Then, in the process of introducing the optical fiber strands 1 ... In parallel and arranged in a line into the coating die 5 at a constant speed and extruding, the circumference is collectively coated with the resin liquid. Then, the coated optical fiber strand 1 ...
Is sent to a curing device 7 provided as a post-process of the coating die 5, and in the course of traveling in the curing device 7, the resin liquid is cured to form a coating layer.
Further, the optical fiber ribbon 8 which is integrated into a tape shape by this coating layer is wound around the winding machine 10 through the winding machine 9 and sent to the subsequent process.

However, in such a conventional method for manufacturing an optical fiber ribbon, the viscosity of the resin liquid is 100 to 2
In order to maintain the range of 000 cps, resin solution is usually 50
It is necessary to keep at a temperature of up to 60 ° C., but when the optical fiber strands 1 ... At room temperature are sent into this resin liquid, the resin liquid near these optical fiber strands 1 ... As a result, the viscosity was increased, and air voids 11 were apt to occur in the optical fiber ribbon 8 obtained as shown in FIG. 5, particularly between the optical fiber strands 1 and 1. If such air voids 11 are present in the optical fiber ribbon 8, the shrinkage in the circumferential direction and the longitudinal direction of the coating layer 13 becomes uneven at low temperature, for example, and microbending is given to the optical fiber, resulting in loss. There is a fear that the loss characteristics such as increase will be adversely affected. In particular,
When the diameter of the optical fiber element wire 1 is 0.2 mm or less, there is a disadvantage that it is easily affected by the diameter.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the occurrence of air voids in the core of an optical fiber tape caused by an increase in the viscosity of a resin liquid during coating. It is to provide the manufacturing method of the core wire.

[0005]

[Means for Solving the Problems] Such a problem is that when a plurality of optical fiber strands are fed into a coating die, and a resin liquid is applied by the coating die and collectively coated,
This can be solved by a method in which the viscosity of the resin liquid is set to 100 to 2000 cps immediately before contact with the optical fiber strand.

[0006]

In the method of manufacturing the optical fiber ribbon according to the present invention, the viscosity of the resin liquid for collectively coating a plurality of optical fiber strands is
100 to 2 even immediately before contact with the optical fiber
Since it is set to 000 cps, the viscosity of the resin liquid in the vicinity of the optical fiber strand does not easily increase even when the optical fiber strand is fed into the coating die, and therefore the circumference of the optical fiber strand, especially the optical fiber strand and the optical fiber strand Since the portion between the wire and the wire is sufficiently wet with the resin liquid, air voids are unlikely to occur in the optical fiber tape core wire.

[0007]

EXAMPLES The present invention will be specifically described below with reference to examples. Here, as one example, a first implementation of a method for producing a four-core optical fiber ribbon 18 using an optical fiber wire 17 obtained by applying a coating 16 to a bare optical fiber 15 as shown in FIG. An example will be described with reference to FIG.

First, a plurality of (four in the drawing) optical fiber element wires 17 ... Which are obtained by applying the coating 16 to the bare optical fiber 15 are prepared. An ultraviolet curable resin is preferably used for forming the coating 16, and as the ultraviolet curable resin, a urethane acrylate resin, an epoxy acrylate resin, a butadiene acrylate resin, a silicone acrylate resin or the like is preferable.

Then, a plurality of (four in the drawing) a plurality of (four in the drawing) feeders 22 ... After that, the optical fiber wires 17 ... Are introduced into the tube 23 in a state of being arranged in parallel and in a line. This tube 23
Is provided in a pre-process of the coating die 25, which will be described later.
A branch pipe 23b is connected in the vicinity. A hot jet 24 is attached to the open end of the branch pipe 23b.
This hot jet 24 sets the viscosity of the resin liquid coating the optical fiber wires 17 ... to 100 to 2000 cps immediately before coming into contact with the optical fiber wires 17 ,. Is for heating the surface temperature of these optical fiber wires 17 ... to 35 to 75 ° C., and hot air of 50 to 100 ° C. is supplied to the pipe 23 via the branch pipe 23 b. .

Then, from the tube 23 to the optical fiber strand 17 ...
Is drawn out and the optical fiber wires 17 ... whose surface temperature is heated to about 35 to 75 ° C. are sent to the coating die 25. The coating die 25 has a viscosity of 100 to 2000 cps and a temperature of 5 from the resin supply pot 26.
The resin liquid at 0 to 60 ° C. is continuously supplied through the resin supply pipe 26a. As the resin liquid, an ultraviolet curable resin is preferably used, and for example, a urethane acrylate-based resin, an epoxy acrylate-based resin, a butadiene acrylate-based resin, or a silicone acrylate-based resin is preferable.

In the process of introducing the optical fiber wires 17 ... Into the coating die 25 at a constant speed and extruding,
The circumference is coated with the above resin solution at once. In the coating die 25, the viscosity of the resin liquid is 100 to 100 even immediately after contact with the optical fiber element wires 17 since the optical fiber element wires 17 are preheated to 35 to 75 ° C. It is kept at 2000 cps. After that, the coated optical fiber wires 17 ... Are led out from the coating die 25, sent to a curing device 27 provided as a post-process of the coating die 25, and run in the curing device 27. Then, the resin liquid is cured to form the coating layer 28. Here, the curing device 27 is an ultraviolet irradiation device when an ultraviolet curable resin liquid is used as the resin liquid, and a device that irradiates ultraviolet rays to cure the resin liquid is used.

Then, the optical fiber tape core wire 18 integrated into a tape form by the covering layer 28 from the curing device 27.
Is taken out, taken up by the take-up machine 29 and taken up by the take-up machine 30, and sent to the subsequent step.

Next, a second embodiment of the manufacturing method of the optical fiber ribbon will be described with reference to FIG. The manufacturing method of this optical fiber tape core wire is different from that of the first embodiment described above, instead of introducing the optical fiber wires 17 ... Into the tube 23, the wound optical fiber wires 17. .. From the process of sending out a plurality of (4 in the drawing) by a plurality of (four in the drawing) feeders 22 ..., a state in which these optical fiber wires 17 ... Then, the steps up to the step of introducing into the coating die 25 are performed in the heating box 31.

In the heating box 31, the optical fiber wire 17 is attached.
A delivery port 31a for delivering the ... To the coating die 25 is formed, and is connected to the heater 33 via a pipe 32. The heater 33 has a viscosity of the resin liquid covering the optical fiber wires 17 ...
In order to achieve 00 cps, the optical fiber strands 17 ... Are heated and the surface temperature of these optical fiber strands 17 ...
The temperature is set to 5 to 75 ° C., and hot air of 50 to 100 ° C. is supplied into the heating box 31 via the pipe 32.

The surface temperature in the heating box 31 is about 35 to 75 ° C.
After being drawn out from the delivery port 31a, they are fed into the coating die 25, and are collectively coated with a resin liquid in the same manner as the above-mentioned first method of producing the optical fiber ribbon. The optical fiber ribbon 18 is formed.

Next, a third embodiment of the method of manufacturing the optical fiber ribbon will be described. The manufacturing method of this optical fiber ribbon is different from the first and second embodiments described above.
In order to make the viscosity of the resin liquid 100 to 2000 cps,
Instead of heating the optical fiber wires 17 ... and sending them into the coating die 25, the resin liquid is heated and supplied to the coating die 25. As an example of the method, in the process of supplying the resin liquid from the resin supply pot 26 to the coating die 25 through the resin liquid supply pipe 26a,
By circulating hot water around the outer periphery of the resin supply pipe 26a, the temperature of the resin liquid immediately before coming into contact with the optical fiber wires 17 ...
Set to 0 to 100 ° C.

In the manufacturing method of the optical fiber ribbon according to these examples, the optical fiber strands 17 ... In order to set the viscosity of the resin liquid to 100 to 2000 cps immediately before coming into contact with the optical fiber strands 17 ...・ Coating die 25
Since it is heated before it is sent to the coating die 25 or the resin liquid is heated and supplied to the coating die 25, even if the optical fiber element wires 17 ... Are sent to the coating die 25, the vicinity of the optical fiber element wires 17 ... The viscosity of the resin liquid does not easily increase, and therefore, the circumference of the optical fiber strands, especially the portion between the optical fiber strands 17 and the optical fiber strands 17 is sufficiently wetted by the resin liquid, so that the optical fiber tape core Air voids in the line 18 can be reduced. Therefore, there is an advantage that the optical fiber ribbon 18 having stable loss characteristics can be obtained.

(Example) First, four optical fiber wires 17 obtained by coating the bare optical fiber 15 with the coating 16 were prepared. Here, the bare optical fiber 15 has a core diameter of 1
A single mode optical fiber having a diameter of 0 μm, a cladding outer diameter of 125 μm, a mode field diameter of 9.5 μm, and a cutoff wavelength of 1.20 μm was used. The outer diameter of the optical fiber strand 17 is 1
It was 70 μm. Then, as shown in FIG. 2, the four optical fiber wires 17 in the wound state were sent out by four sending machines 22, respectively. Then, four optical fiber wires 17 were introduced into the tube 23, to which hot air of 70 ° C. was supplied from the hot jet 24, at a linear velocity of 100 m / min in parallel and in a line. This tube 23 had a length in the longitudinal direction of about 1 m.

Then, the four optical fiber wires 17 are led out from the tube 23, and the optical fiber wires 17 whose surface temperature is about 50 ° C. are applied to the coating die 25 at a linear velocity of 100 m /
Sent in minutes. The coating die 25 has a viscosity of 1000 cps and a temperature of 4 from the resin supply pot 26.
An ultraviolet curable resin liquid at 5 ° C. was continuously supplied. Then, in the process of introducing and extruding the four optical fiber wires 17 into the coating die 25 at a constant speed, the circumference thereof was collectively covered with the ultraviolet curable resin liquid. The viscosity of the ultraviolet curable resin liquid in the coating die 25 was 900 cps immediately before contact with the optical fiber strand 17. Then, the four coated optical fiber wires 17 are led out from the coating die 25, and then sent to a curing device (ultraviolet irradiation device) 27, and the curing device 27
In the process of traveling inside, the ultraviolet curable resin liquid was cured to form the coating layer 28.

Next, the optical fiber ribbon 18 which is integrated into a tape form from the curing device 27 by the coating layer 28.
Was taken out and wound on the winder 30 via the take-up machine 29. Optical fiber tape core wire 1 thus obtained
8 had a width W of 0.8 mm and a thickness T of 0.2 mm.
The thickness of the coating layer 28 was 200 μm.

Comparative Example An optical fiber ribbon was obtained in the same manner as in Example except that the four optical fiber wires 17 were not inserted into the tube 23.

Next, the total length of air voids existing in the optical fiber ribbon 1 m obtained in Examples and Comparative Examples was examined. As a result, the total length of air voids in the optical fiber ribbon of the example was 0 mm.
On the other hand, the total length of the air voids in the optical fiber ribbon of the comparative example was 1524 mm.

Further, the loss increase of the optical fiber wire 17 when the optical fiber ribbons obtained in Examples and Comparative Examples were left at an ambient temperature of -40 ° C. was measured by a power meter. The measurement wavelength was 1.55 μm. The results are shown in Table 1 below.

[0024]

[Table 1] In Table 1, ~ is in the optical fiber ribbon of FIG.
Is the optical fiber element wire at the position. The unit of numerical values in Table 1 is dB / km (-40 ° C).

As is clear from these results, the optical fiber tape core wire obtained by the manufacturing method of the comparative example in which the optical fiber element wire 17 is not heated has many air voids, and the loss increases at low temperatures. there were. In comparison with this, the optical fiber tape core wire obtained by the manufacturing method of the embodiment in which the optical fiber wire 17 is heated and then sent to the coating die 25 has no air voids and has excellent loss characteristics at low temperature. Met.

(Test Example) In the first embodiment of the method for manufacturing the optical fiber ribbon described above, the occurrence of air voids when the temperature for heating the optical fiber strand 17 is changed, the optical fiber ribbon The shape and loss temperature characteristics of the optical fiber ribbons obtained by this method were investigated. The loss temperature characteristic was measured by using a power meter to measure the increase in loss of the optical fiber element wire 17 when the optical fiber element wire 17 was left to stand in an ambient temperature of -40 ° C. The measurement wavelength was 1.55 μm. The results are shown in Table 2 below.

[0027]

[Table 2]

In Table 2, NO. Is the optical fiber tape core wire that uses optical fiber wires heated at different temperatures, the viscosity is the viscosity of the resin liquid that collectively coats the optical fiber wire, and the length is the total length of the air voids in the optical fiber tape wire. Represents

In the results shown in Table 2, the shape of the optical fiber ribbon is NO. The sample No. 1 had a deformed cross-sectional shape, but the others were good. It is considered that this is because the viscosity of the resin liquid is too small. Regarding the occurrence of air voids, see NO. It frequently occurred in the optical fiber ribbons of 8 and 9. For the loss temperature characteristics, see NO. The optical fiber ribbons of 8 and 9 had a large loss increase at a low temperature and were inferior in loss characteristics. From these facts, the viscosity of the resin liquid immediately before contacting the optical fiber strand should be 100 to 2000 cps,
It can be seen that an optical fiber ribbon having excellent characteristics can be obtained only when the optical fiber strand is heated.

[0030]

As described above, in the method of manufacturing an optical fiber ribbon according to the present invention, the viscosity of the resin liquid that collectively coats a plurality of optical fiber strands is set to 100 before the contact with the optical fiber strands. Since it is about 2000 cps, the resin liquid in the vicinity of the optical fiber strand does not easily grow even when the optical fiber strand is sent to the coating die, and therefore the circumference of the optical fiber strand, especially the optical fiber strand and the optical fiber strand Since the portion between the fiber strand and the fiber strand is sufficiently wet with the resin liquid, it is possible to reduce air voids in the optical fiber ribbon. Therefore, there is an advantage that an optical fiber ribbon having stable loss characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an optical fiber ribbon according to a method for producing an optical fiber ribbon according to the present invention.

FIG. 2 is a schematic view for explaining the first embodiment of the method for producing an optical fiber ribbon according to the present invention.

FIG. 3 is a schematic view for explaining a second embodiment of the method for producing an optical fiber ribbon according to the present invention.

FIG. 4 is a schematic diagram for explaining a conventional method for manufacturing an optical fiber ribbon.

FIG. 5 is a cross-sectional view showing an example of an optical fiber ribbon according to a conventional method for producing an optical fiber ribbon.

[Explanation of symbols]

17 ... Optical fiber element wire, 18 ... Optical fiber tape core wire, 23 ... Tube, 24 ... Hot jet, 25 ... Coating die, 26 ... Resin supply pot, 26a ...・ Resin supply pipe, 28 ... coating layer, 31 ... heating box, 33 ... heater

Claims (3)

[Claims] 1. When a plurality of optical fiber strands are fed into a coating die and a resin liquid is applied by the coating die to collectively coat the resin liquid, the viscosity of the resin liquid is measured immediately before contact with the optical fiber strands. A method for producing an optical fiber ribbon, characterized in that the fiber length is 100 to 2000 cps. 2. The viscosity of the resin liquid according to claim 1,
A method for producing an optical fiber ribbon, which comprises heating an optical fiber strand and sending it to a coating die so as to obtain 0 to 2000 cps. 3. The resin liquid according to claim 1, having a viscosity of 10
A method for producing an optical fiber ribbon, wherein a resin liquid is heated and supplied to a coating die so as to obtain 0 to 2000 cps.