JPS636504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating an optical fiber in which the passage speed of the optical fiber through the coating material can be increased by increasing the hydraulic pressure of the coating material.

Optical fibers used as optical transmission media are
Usually, the diameter is 200 μm or less, and since the material is very fragile, surface scratches are likely to occur during manufacturing or during the process of making cables. These surface flaws become a stress concentration source and easily break when external force is applied. For this reason, it is extremely difficult to use optical fiber as it is as an optical transmission medium.To solve this problem, after spinning the optical fiber, a resin coating is subsequently applied to the outer circumference of the optical fiber to create an optical fiber. It is common practice to protect the material, thereby maintaining its initial strength and increasing its durability.

By the way, the spinning speed of optical fibers is becoming increasingly faster from the viewpoint of mass production and economic efficiency of optical fibers, but there is a limit to the coating speed of the resin coating mentioned above, which is a factor that hinders speed increases. ing. Normally, when forming a resin coating on the outer circumference of an optical fiber, a method is adopted in which the optical fiber is passed through a die filled with liquid resin. Because it relies on the natural flow of the coating material that accompanies the movement of the fiber, it has the disadvantage that when the spinning speed of the optical fiber increases, interfacial peeling occurs between them and the coating material no longer adheres to the optical fiber. Since the spinning of the optical fiber and the application of the coating material are continuous processes, the spinning speed of the optical fiber is substantially limited by the applicability of the coating material to the optical fiber. The speed is only around 100m/min at most.

The present invention makes it possible to increase the spinning speed of optical fiber by increasing the pressure of the coating material in the die, and the structure is such that the optical fiber spun into a solution of the coating material is spun each time. A coating method in which the coating material is applied to the outer periphery of the optical fiber by passing the optical fiber at a speed of 100 meters per minute or more, characterized in that a solution of the coating material is supplied under pressure.

The present invention will be explained in detail below based on the drawings. FIG. 1 schematically shows the configuration of an apparatus for carrying out the coating method of the present invention. The lower end of the optical fiber base material 1 is heated to approximately 1800 mm by the heating element 3 provided inside the electric furnace 2.
It is melted and spun by heating at a temperature of ℃ to 2000℃. The spun optical fiber 4 is wound around a roller 11 at a constant speed of 100 m to 500 m per minute. In this case, a coating container 7 for applying the coating solution 17 and a dryer 12 for drying the coating solution 17 are provided between the electric furnace 2 and the winding roller 11. The coating container 7 stores the coating material solution 17, and the spun optical fiber 4 is stored therein.
The coating material solution 1 is applied to the outer periphery of the optical fiber 4 by passing through it.
7, and a supply port 10 for a coating material solution 17 is provided in the side wall portion. Also, the second
As shown in the figure, the upper surface of the coating container 7 is provided with a fiber inlet 8 that leads to the interior, and the lower part has a tapered conical shape in order to improve the flow of the coating material solution 17, and a fiber outlet 9 is provided at the lower end. It is provided. Furthermore, the fiber inlet 8 of the coating container 7
A fin 13 for preventing backflow is provided on the inner wall of the coating container 7 and projects obliquely toward the inside of the coating container 7. On the other hand, a supply device 5 for supplying a coating solution 17 is connected to the supply port 10 of the coating container 7 via a supply pipe 18, and the coating solution 17 is pressurized into the coating container 7 by the supply device 5. Supplied.

In the above device structure, the faster the spinning speed of the optical fiber 4 is, the higher the liquid pressure of the coating solution 17 is,
To facilitate coating on the outer periphery of an optical fiber 4. In this case, by increasing the liquid pressure in the coating container 7,
The coating solution 1 follows the pulling out of the optical fiber 4.
7 can be sequentially extruded from the fiber outlet 9,
A uniform coating effect can be obtained. Further, since the fins 13 are provided at the fiber inlet 8 of the coating container 7 when increasing the liquid pressure, backflow of the coating material solution 17 to the fiber inlet 8 due to the increase in pressure is prevented.

Next, another embodiment of the coating container 7 is shown in FIG. The coating container 7 is provided with a screw 14 for pushing out the coating solution 17 therein, and is further provided with a motor 15 and a power transmission system 16 for rotating the screw 14. In the coating container 7, the pressure of the coating solution 17 near the fiber outlet 9 in the coating container 7 can be adjusted by arbitrarily changing the rotation of the screw 14, so that the coating solution 17 can be adjusted regardless of the passing speed of the optical fiber 4. 17 can be reliably coated onto the optical fiber 4.

In the two embodiments described above, the outer periphery of the optical fiber 4 is coated with the coating solution 17 according to the passing speed of the optical fiber 4. A device for measuring the outer diameter of the fiber 4 is provided, and the output signal is sent to the supply device 5.
It is also possible to provide feedback and adjust the coating thickness as desired. In addition to this, the bottom of the coating container 7 may be evacuated if necessary.

According to the present invention as described above, coating of the coating material can be accelerated by increasing the liquid pressure of the coating material solution, which is significantly limited by the coating properties of the coating material and the optical fiber surface. The spinning speed of optical fibers can be greatly improved. Incidentally, the coating speed of optical fiber is faster than the conventional coating speed per minute.
It can travel more than 100 meters at a speed of about 500 meters per minute. Further, the coating material can be applied to a thickness of 50 μm to 300 μm.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus configuration for implementing the present invention;
2 and 3 are structural sectional views of the coating container. In the drawing, 1 is an optical fiber base material, 2 is an electric furnace, and 3 is
is a heat generating material, 4 is an optical fiber, 5 is a supply device, 6 is a storage tank, 7 is a coating container, 8 is a fiber inlet, 9 is a fiber outlet, 10 is a supply port, 11 is a winding roller, 12 is a dryer, 13 is a fin, 14 is a screw, 15 is a motor, 16 is a power transmission system, 17
1 is a coating solution, and 18 is a supply pipe.

Claims (1)

[Claims] 1 Optical fiber spun into a solution of coating material per minute
A method for coating an optical fiber, wherein the coating material is applied to the outer periphery of the optical fiber by passing the optical fiber at a speed of 100 meters or more, characterized in that a solution of the coating material is supplied under pressure.