JPH0570182A - Production of optical fiber element wire - Google Patents

Abstract

PURPOSE:To provide a method for producing an optical fiber element wire by forming a thin film having a uniform film thickness on an optical fiber bare wire from a coating resin solution. CONSTITUTION:An optical fiber element wire 19 is produced by a method for passing an optical fiber bare wire 18 through a coating die 11 in which a resin coating solution is stored and forming a coating resin film on the outer periphery of the optical fiber bare wire 18. In the process, plural coating resin feed holes 14 are circumferentially arranged and formed in the upper part of the coating die 11 and a coating resin solution is then fed from the coating resin feed holes 14 to form a thin film of the coating resin solution. The optical fiber bare wire 18 is then passed through the thin film and the viscosity of the above-mentioned coating resin solution is regulated to >=5000 cP.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of an optical fiber bare wire in which a coating resin solution is brought into contact with a bare optical fiber to form a thin film of the coating resin solution having a uniform thickness on the outer circumference of the bare optical fiber. Regarding the method.

[0002]

2. Description of the Related Art A conventional optical fiber strand is manufactured by using a coating die 1 as shown in FIG. Coating die 1
Is provided with a supply port 2 on its side surface, and the coating resin solution 4 that has passed through the supply pipe 3 is sent from the supply port 2 into the coating die 1 and stored therein. Further, an inlet port 5 for the bare optical fiber leading to the inside is provided in the upper part of the coating die 1, and a lower part thereof has a tapered conical shape in order to improve the flow of the coating resin solution 4, At its lower end, an outlet 6 for the optical fiber wire is provided. A method for producing an optical fiber element wire using such a coating die 1 is as follows. The optical fiber bare wire 7 melt-spun in a heating furnace is inserted into the coating die 1,
In this, when the coating resin solution 4 is brought into contact with the bare optical fiber 7, a coating resin layer is formed on the outer periphery of the bare optical fiber 7, and the optical fiber bare wire 8 is obtained.

By the way, recently, there is an increasing demand for a thin optical fiber element wire having a thin coating layer. In the above-described method for manufacturing an optical fiber element wire, the outlet 6 of the coating die 1 is used. Since the coating thickness is defined by the gap with the bare optical fiber 7, the gap becomes very narrow and the bare optical fiber 7 comes into contact with the outlet 6 and the surface of the bare optical fiber 7 In this case, minute defects are likely to occur, and the optical fiber element wire 8 having a uniform coating resin layer thickness cannot be obtained. The optical fiber element wire 8 in which the thickness of the coating resin layer is not uniform has a drawback that the optical transmission characteristics are deteriorated.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing an optical fiber bare wire which forms a thin film of a coating resin solution having a uniform film thickness on the outer circumference of a bare optical fiber. ..

[0005]

An object of the present invention is to insert an optical fiber bare wire into a coating die in which a coating resin solution is stored and to form a coating resin film on the outer circumference of the bare optical fiber. In the manufacturing method of the wire, on the upper part of the coating die, a plurality of coating resin supply holes are formed side by side in a circumferential shape, and the coating resin solution is supplied from these coating resin supply holes to form a thin film of the coating resin solution, A bare optical fiber is inserted into this thin film, and the viscosity of the coating resin solution is adjusted to 5000.
It is solved by a method of setting cps or more.

An example of the present invention will be described below in detail with reference to the drawings. 1 and 2 are a perspective view and a sectional view showing an example of a coating die 11 used for manufacturing the optical fiber element wire of the present invention. The coating die 11 is in the shape of a sliver and has an inlet 1 for the bare optical fiber that leads to the inside of the die 1
2 is provided, an outlet 13 for the optical fiber element wire is provided in the lower part thereof, and a plurality of coating resin supply holes 14 are circumferentially arranged in the upper part thereof. Also,
An annular manifold 1 is provided on the outer periphery of the coating die 11.
5 is provided so as to surround the coating resin supply hole 14, and the manifold 15 is connected to a supply pipe 17 for supplying the coating resin solution 16.

The coating resin solution 16 is temporarily stored in the manifold 15 through the supply pipe 17, and is sent from the individual coating resin supply holes 14 toward the outlet 13 of the optical fiber element wire. Merge near the and exit 13
A thin film of the coating resin solution 16 having a uniform film thickness is formed. The inlet 12 is circular and has an outer diameter of 10 mm.
The above is preferable, and the outlet 13 has a circular shape and its outer diameter is preferably about 1 mm to 5 mm. However, since these depend on the outer diameter of the bare optical fiber to be inserted, the outlet is not necessarily within the above range. Absent. The shape of the coating resin supply hole 14 is preferably circular and has an outer diameter of about 1 to 7 mm.
The outer diameter is preferably about 1 mm. The intervals at which the coating resin supply holes 14 are circumferentially arranged on the upper portion of the coating die 11 are equal to each other in the range of about 1 to 3 mm.

To manufacture an optical fiber elemental wire using the coating die 11 as shown in FIGS. 1 and 2, the following steps are performed. First, an optical fiber preform is prepared and melt-spun in the heating furnace 1 at a speed of about 500 to 800 m / min to form a bare optical fiber 18 having an outer diameter of about 125 μm.
On the other hand, a coating resin solution 16 such as an ultraviolet curable resin solution having a viscosity of 5000 cps or more is prepared by adding about 0.5 to 2.0% by weight of a surfactant such as a silane coupling agent which is usually used in advance. Is supplied into the coating die 11 through the coating resin supply hole 14, and the coating resin solution 16 having a uniform film thickness is provided in the vicinity of the outlet 13 provided in the coating die 11.
To form a thin film. The film thickness of the thin film of the coating resin solution 16 is adjusted to 0.5 to 0.5 by adjusting the supply amount of the coating resin solution 16.
It is preferably about 1.5 mm. Here, the surfactant is used by adding the surfactant to the coating resin solution 16 to reduce the surface tension of the coating resin solution 16,
This is because a thin film of the coating resin solution having a uniform film thickness is formed at the outlet 13 provided in the coating die 11. Further, when the viscosity of the coating resin solution 16 is 5000 cps or less, the outlet 13
It is not preferable because there is an inconvenience that the thickness of the thin film of the coating resin solution becomes uneven, and the surface of the optical fiber element wire coated with this thin film becomes uneven.

Next, the bare optical fiber 18 is connected to the inlet 1
When it is inserted from 2 into the coating die 11, it passes through a thin film of the coating resin solution having a uniform film thickness formed at the outlet 13,
The bare optical fiber 18 contacts the coating resin solution 16, and a thin film of the coating resin solution 16 having a uniform film thickness of 5 μm or less is formed on the outer periphery of the bare optical fiber 18. Then, by irradiating it with ultraviolet rays, the thin film of the coating resin solution 16 formed on the outer circumference of the bare optical fiber 18 is cured or solidified,
The intended optical fiber strand 19 is obtained. In this way, a thin film of the coating resin solution 16 is formed near the outlet 13 provided in the coating die 11, and the bare optical fiber 18 is inserted into this thin film. Since the thickness of the thin film of the solution 16 is determined, it is not necessary to reduce the opening diameter of the outlet 13, and the opening diameter of the outlet 13 can be made relatively large. Therefore, the bare optical fiber 18 does not come into contact with the outlet 13, and it is possible to prevent the surface of the bare optical fiber 18 from being scratched and preventing the thin film of the coating resin solution from being uneven in thickness.

[0010]

As described above, according to the method for manufacturing an optical fiber bare wire of the present invention, the bare optical fiber is inserted into the coating die in which the coating resin solution is stored, In the method for manufacturing an optical fiber element wire in which a coating resin film is formed on the outer periphery, a plurality of coating resin supply holes are formed side by side in a circular shape on the upper part of the coating die, and the coating resin solution is supplied from these coating resin supply holes. By forming a thin film of the coating resin solution, inserting the bare optical fiber into the thin film, and setting the viscosity of the coating resin solution to 5000 cps or more, a uniform film thickness can be obtained on the outer circumference of the bare optical fiber. A thin film of the coating resin solution can be formed. Further, in the thus obtained optical fiber element wire, minute defects are less likely to occur on the surface of the bare optical fiber, and a thin film of coating resin having a uniform film thickness is formed, so that the optical transmission characteristics are improved. To do.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a coating die used for manufacturing an optical fiber element wire of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a coating die used for manufacturing an optical fiber element wire of the present invention.

FIG. 3 is a schematic cross-sectional view showing a coating die used for manufacturing a conventional optical fiber strand.

[Explanation of symbols]

11 ... Coating die, 14 ... Coating resin supply hole, 16 ...
Coating resin solution, 18 ... bare optical fiber, 19 ... bare optical fiber

Claims (2)

[Claims] 1. A method for producing an optical fiber bare wire, wherein a bare optical fiber is inserted into a coating die in which a coating resin solution is stored, and a coating resin film is formed on the outer circumference of the bare optical fiber. A plurality of coating resin supply holes are arranged in a circle on the top of the, and the coating resin solution is supplied from these coating resin supply holes to form a thin film of the coating resin solution. A method for manufacturing an optical fiber elemental wire, which comprises: 2. The method for producing an optical fiber element wire according to claim 1, wherein a coating resin solution having a viscosity of 5000 cps or more is used.