JPS58223640A - Preparation of pipe coating type optical fiber - Google Patents

Abstract

PURPOSE:To make it possible to prepare continuously the titled optical fiber having improved mechanical characteristics, transmission characteristics, shape and performance, etc., by forming the inner layer of a pipe from a noncrystalline resin, and forming the outer layer from a crystalline resin. CONSTITUTION:An optical fiber 1 having a buffer layer 3 is fed into a nipple (B) of a crosshead (A), and a viscous material 4 is fed into the nipple (B) while heated with a storing part (C), a supply pipe (D) and a heater (E). A noncrystalline resin 5', e.g. polycarbonate, is fed to a resin path (F), and a crystalline resin 6', e.g. polybutylene terephthalate, is fed to a resin path (H). Thus, the noncrystalline resin 5' is formed into a pipe as an inner layer 5 of a pipe 7, and the optical fiber 1 and the viscous material 4 are introduced into the inner layer 5 at the same time. On the other hand, the crystalline resin 6' is formed into a pipe on the outer periphery of the inner layer 5 as an outer layer 6 of the pipe 7. These members are continuously extruded from the crosshead (A) to give the aimed pipe coating type optical fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pipe-coated optical fiber.

Pipe coated optical fiber is a type of optical fiber wire, and the general coated optical fiber consists of a primary coating layer (primary coat 1) and a buffer layer (buffer coat 1).
) is sequentially formed on the outer periphery of the fiber, which is coated with a resin pipe, and a viscous material in the shape of a diagonal or an ellipse is interposed between the outer periphery of the buffer layer and the inner layer of the pipe.

The pipe-coated optical fiber mentioned above is longer than the ζ-beam, and the optical fiber is flexible and is stored in the pipe in a large bend without micro-bends, so it is durable. Improve the protective effects of optical fibers such as tensile strength, lateral pressure resistance, and cushioning properties.
Although there is a prospect of securing good Qf transmission characteristics,
When the outer periphery of an optical fiber is coated by extrusion molding means, the following problems occur, making it impossible to obtain the necessary fiber properties, and on the contrary, this results in worse results.

In other words, when a pipe is formed around the outer periphery of a buffer-coated optical fiber by extrusion molding, and a viscous phase is interposed between the outer periphery of the buffer layer and the inner periphery of the pipe, a desired pipe-covered optical fiber is produced. If a crystalline resin piped into a pipe is stored in the crosshead of an extrusion molding machine at a high temperature, the temperature will be lower than this! Although it comes into contact with the viscous material of iA,
In this way, when the viscous A (low temperature) comes into contact with the viscous A (high temperature), the inner surface of the pipe will partially solidify and the solidified material will obstruct the flow of the supplied resin. In the extrusion molding machine, fiber breakage accidents and intermittent filling of resin occurred in the extrusion molding machine, causing clogging conditions such as f times, and solidified material that was the cause of the clogging fell off and got mixed into the pipe, resulting in poor molding. The state is no longer available.

Of course, the problem Vi on the pipe side can be solved by omitting the active phase, but in such a case, the lubricity inside the pipe is lost, so the optical fiber exhibits a non-uniform bending state in the longitudinal direction within the pipe. This will lead to an increase in transmission loss.

On the other hand, crystalline resin, which is a pipe material, is also required mechanically! Since the lunar quality is indispensable for obtaining temporality, it cannot be replaced by other compatibility.

Therefore, when manufacturing an optical fiber coated with an extrusion molding method using an active phase, a crystalline resin, as an essential component, unless solutions to the problems mentioned above are devised, the performance will be poor.
It is not possible to obtain products of excellent quality, and therefore, effective improvement measures to deal with this problem are desired.

In view of the above-mentioned circumstances, the present invention is an improvement on the extrusion method for coating an optical fiber pipe, and the specific method thereof will be explained below with reference to the illustrated embodiments.

Figure 1 shows an extrusion molding machine with only the crosshead shown.
FIG. 2 shows the optical fiber before the pipe is coated, and FIG. 3 shows the optical fiber after the pipe is coated.

The optical fiber (1) before being coated with the pipe in the above (1) is made of quartz, and on its outer periphery there is a primary coating layer (2) made of silicone resin, and a buffer layer (2) also made of silicone resin.
3) is formed.

In some cases, only one layer serving as the primary coating layer (2) and the buffer layer (3) may be formed on the outer periphery of the optical fiber il+.

In FIG. 1, the optical fiber with the buffer layer (3) (
1) is unwound from a feeder (not shown) and fed into nipple B of Chronoheno l-A.

A supply pipe I] equipped with a reservoir C of an active phase (4) consisting of oil/recone oil, etc. is connected to the rear end of this Nisoglu B, and a viscous phase (4) is connected to the reservoir C1 supply pipe D1 nipple. It is supplied into the nipple B while being heated by the heater FJ wrapped around the rear end of the nipple B.

Inside the crosshead A, there is an inner layer die G1 that corresponds to the Nisoflu B and forms a resin flow path F, and an outer layer die I that corresponds to the inner layer die G and forms a resin flow path I. The resin flow path F is supplied with a non-crystalline resin (5)' such as polycarbonate from a supply section (not shown), and the resin flow path H+ is supplied with a non-crystalline resin (5)' such as polycarbonate. Crystalline resin (6)' is supplied from a supply section (not shown).

Therefore, when extrusion molding is performed as described above, the amorphous resin (5)' is used as the inner layer (5) of the pipe (7) to form the pipe shape i.
As this is formed, the optical fiber (1) and the viscous material (4) enter into the inner layer (5), and on the other hand,
Since the crystalline resin (6)' is formed in a pipe shape as the outer layer (6) of the pipe (7) to the outer periphery of the inner layer (5), each of these parts is continuously extruded through the crosshead A to form the third layer. A pipe-coated optical fiber as shown in the figure is obtained.

After exiting the crosshead A, the pipe-coated optical fiber passes through a cooling tank where it is cooled to a predetermined temperature, and then is passed through a take-up machine and wound up by a take-up machine. During molding, the optical fiber (1)
The feeding speed is set higher than the extrusion speed of the pipe (7), and the optical fiber (1) is made to have an extra length with respect to the pipe (7).

Next, the results of implementing a specific example of the method of the present invention described in FIG. 1 under the following conditions will be explained.

Optical fiber (1) diquartz-based, core diameter 5011 m, outer diameter 125/1 m, primary coating layer (2): silicone resin, outer diameter 200/1 m
Buffer layer (3): Silicone resin, outer diameter 400μm Viscous material (4): Silicone oil, filling temperature 180℃
Inner layer I5): polycarbonate 1, outer diameter 10, meat 1
i50/Rn, extrusion temperature 300℃ Outer layer (f, i): polybutylene terephthalate, outer diameter 12 layers, extrusion 44 degrees 300℃ The transmission loss is almost the same before and after the pipe is coated, and the mechanical properties are sufficient, so even if continuous extrusion molding is performed for more than 1 hour, the resin will not flow into the resin flow paths F and H. There was no curing of the resin or clogging of the flow paths F and H, the wall thickness of the pipe (7) was uniform in the longitudinal direction (the stiffness was uniform), and no deterioration of the viscous phase (4) was observed. Ta.

” - The reason why the good results were obtained is that the viscous phase (,1)
The temperature (180℃) is the temperature of both resins [5)'i6)' (
Although the temperature is well below 300°C, the resin (5)' for the pipe inner layer that comes into direct contact with the viscous layer (4) is amorphous, so it does not react with the activated H (4) at low temperature. On the other hand, the resin for the outer layer of the pipe (6)'
Even if it is crystalline, it does not solidify because it does not come into contact with the low-temperature viscous phase (4), and therefore both resins i51
'[(i)' does not cause trouble such as blockage in the crosshead A, and as a result, the extrusion state of the pipe (7) is stable for a long time, and the physical properties, chemical properties, A pipe coating with excellent shape and structure can be obtained.

In addition, if the solidification of the resin can be stopped as described above,
In order to eliminate the temperature difference between the resin and the viscous phase (4), the active H
There is no need to raise the temperature of (4) to an extremely high temperature, and therefore the viscous phase (4) does not deteriorate due to high temperatures.

By appropriately covering the pipe in this manner, no increase in transmission loss of the optical fiber (1) is observed, and high transmission characteristics can be ensured.

For comparison, under the same conditions as in the specific example described in Ail, only crystalline polybutylene terephthalate was used as the resin for pipe molding, and a single layer pipe made of this crystalline resin (
The buffer-attached optical fiber was coated with inner diameter/outer diameter = 0.8 mm/1,2 mm), and further (with active H(
When a pipe-covered optical fiber was made at a temperature of 180°C, solidified polybutylene terephthalate was deposited intermittently on the outer periphery of the pipe one hour after the start of extrusion. It started to stick to the target.

In addition, in Comparative Example 1 above, the temperature of the viscous phase was set at 240° to
When the pipe was coated by increasing the temperature to 250℃, the previous example (・
In any case, the f=J adhesion phenomenon of the assimilated resin still occurs, and if the temperature of the viscous phase is increased to 250°C or higher, the deterioration of this is serious and impractical. there were.

υAs explained above, according to the present invention, a buffer layer is formed around the optical fiber. A method for manufacturing a pipe-coated optical fiber in which active H is synchronously interposed between the outer circumference of the buffer layer and the inner circumference of the buffer layer. Since the inner layer of the pipe is made of resin and the outer layer of the pipe is made of crystalline resin, troubles caused by the temperature difference between the pipe molding resin and the activated H will not occur. It is possible to continuously manufacture pipe-coated optical fibers with excellent performance and quality, including mechanical properties, transmission properties, shape, appearance, etc.

[Brief explanation of drawings]

Fig. 1 is an explanatory view of the mounting part showing one embodiment of the method of the present invention, Fig. 2 is a sectional view showing a pipe-covered & Mf+ optical fiber, and Fig. 3 is a pipe-covered type manufactured by the method of the present invention. FIG. 2 is a cross-sectional view of an optical fiber. +11...Fiber (2)...Primary coating layer (3)...Buffer layer (4)...Active H 15)Φ-・Middle/inner layer ( 5)'...Amorphous resin (6)...Outer layer (6)'...Crystalline resin (7)・ol,・pipe

Claims (1)

[Claims] A buffer layer is formed on the outer periphery of the bifiber, and a pipe is coated on the outer periphery of the buffer layer by extrusion molding, and in synchronization with this extrusion, viscosity is created between the outer periphery of the buffer layer and the inner periphery of the pipe. 1. There is a phase involved. In the method for manufacturing a pipe-covered optical fiber, the extrusion molding means described in - 1 is used to form the inner layer of the pipe from 1 amorphous resin during pipe molding;
A method for manufacturing a pipe-covered light beam characterized by forming the outer layer of a crystal + 1 resin (resin) and 2-repipe.