JPH04254440A - Method and apparatus for producing optical fiber - Google Patents

Abstract

PURPOSE:To obviate the generation of stuck mists and evaporated matter or the mists stagnating in a light transmittable cylindrical body 6 in a photoirradiation device 11 and to substantially prevent the generation of light absorption by this generation as well as to maintain high light intensity over a long period of time by reducing the inside diameter of the above- mentioned cylindrical body 6 and increasing the flow rate of an inert gas. CONSTITUTION:(1) This invention relates to the process for producing the optical fiber by using the photoirradiation device 1 in which the inside diameter of the light transmittable cylindrical body 6 is reduced to <=10mm and by increasing the flow rate of the inert gas to be passed in the light transmittable cylindrical body 6 to >=10L/min in the process for producing the optical fiber formed with a coating by applying a photosetting resin on the optical fiber 1, then passing the optical fiber in the light transmittable cylindrical body 6 and curing the photosetting resin by irradiating the resin with light from the outer periphery of this cylindrical body 6. (2) The photoirradiation device which reduces the inside diameter of the light transmittable cylindrical body 6 to <=10mm is provided as the photoirradiation device which forms the coating by applying the photosetting resin on the optical fiber 1, then passing the optical fiber in the light transmittable cylindrical body 6 and curing the photosetting resin by irradiating the resin with the light from the outer periphery of this cylindrical body 6.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an apparatus for manufacturing optical fibers used for optical communication and a method for manufacturing optical fibers using the same, and particularly to a light irradiation apparatus for curing photocurable resin for coating optical fibers. Regarding improvements.

[Conventional technology]

[0002] Optical fibers are used coated with various resins for the purpose of mechanical protection, and photocurable resins are generally used from the viewpoint of productivity. FIG. 2 is a conceptual diagram showing a conventional optical fiber manufacturing apparatus and an optical fiber manufacturing method using the same.

Here, the drawn optical fiber 3 is coated with a photocurable resin by a resin coating device 4, and when it passes through a cylindrical body 6 in a light irradiation device 11, light emitted from a light irradiation lamp 5 is applied. is cured to form a single or multi-layer resin coating layer, which is wound up by a winder 8 to form a resin coating layer optical fiber 7.
is manufactured.

In this case, the light for curing the resin is usually ultraviolet rays, the source of this ultraviolet light is mainly a mercury lamp, and the cylindrical body is generally a quartz tube due to its transparency to ultraviolet rays. It is used.

[0005]

[Problems to be Solved by the Invention] In conventional devices of this kind, when the resin coated on the optical fiber in the cylindrical body 6 is cured by being irradiated with light, the resin absorbs the heat ray component in the irradiated light. The light from the light irradiation lamp does not cause any damage to the inner surface of the cylindrical body 6 because it absorbs heat and generates heat due to reaction heat during curing, generating mist and volatile components, which tend to adhere to the inner surface of the cylindrical body 6. It is absorbed and attenuated by the kimono, reducing its ability to harden. Therefore, there are problems in increasing the linear speed during optical fiber production or in continuous operation over a long period of time.

[0006] Furthermore, as a solution to the above problem, a method has been proposed in which the hot ray component of the irradiated light from the light irradiation lamp is blocked by flowing gas or the like in order to lower the fiber temperature. There was a problem that the maintenance of the equipment was time-consuming and expensive (Japanese Patent Application Laid-Open No. 1999-1-
148733).

[0007]

[Means for Solving the Problems] As a result of studies in order to solve various conventional problems, the present inventors have developed a light-transmitting cylindrical body 6 in a light irradiation device 11 in an apparatus for manufacturing optical fibers. The present invention was completed by discovering a method for reducing the inner diameter and increasing the flow rate of inert gas.

That is, the present invention provides: (1) After applying a photocurable resin to an optical fiber, the optical fiber is passed through a light-transmitting cylindrical body, and light is irradiated from the outer periphery of the cylindrical body to form the photocurable resin. In an optical fiber manufacturing method in which a coating is formed by curing a resin, the inner diameter of the light-transmitting cylindrical body 6 is set to 10 mm or less, and the flow rate of the inert gas flowing into the light-transmitting cylindrical body 6 is set to 10 mm or less.
This invention relates to a method for manufacturing an optical fiber, characterized in that the optical fiber is coated with a photocurable resin, and then passed through a light-transmitting cylindrical body, and the cylindrical body is A light irradiation device that irradiates light from the outer periphery to cure the photocurable resin to form a coating, characterized in that the light-transmitting cylindrical body has a small inner diameter of 10 mm or less. I will provide a.

The present invention will be explained in detail below based on the drawings. FIG. 1 shows that when the photocurable resin coated on the optical fiber 3 is passed through a light irradiation device, particularly an ultraviolet irradiation device 11, to be cured, a thin tube with an inner diameter of 10 mm or less is used as a cylindrical body 6 in the ultraviolet irradiation device 11. FIG.

In the present invention, it is important that the inner diameter of the cylindrical body 6 installed in the light irradiation device 11 is extremely small, 10 mm or less. When the inner diameter of the cylindrical body exceeds 10 mm, it is difficult to obtain the expected flow rate. In this way, since the cylindrical body 6 has a small diameter, the flow rate of the inert gas flowing through the cylindrical body 6 increases, and the generated mist and volatile components are transferred to the cylindrical body 6.
It does not accumulate on the surface and is easily discharged to the outside. For this purpose, it is necessary that the flow rate is 10 L/min or more, and if it is less than this, the desired effect cannot be obtained.

[0011] As the material constituting the cylindrical body 6, a transparent material such as quartz, which does not impair the transmission of irradiation light such as ultraviolet light, is preferably used. The photocurable resin used to coat the optical fiber 3 is not particularly limited, but it can be easily cured by light such as ultraviolet rays, such as urethane (
meth)acrylate, epoxy(meth)acrylate,
Examples include ester (meth)acrylate. The photocurable resin coated on the optical fiber may be a single layer or a multilayer.

0012

[Operation] The mechanism by which the mist and volatile components generated from the resin material coated on the optical fiber adhere to the cylindrical body is not clear, but the mist and volatile components in the purge gas such as nitrogen are attached to the material such as quartz. It is presumed that the material is cooled on the surface of the cylindrical body, and as a result, it adheres to the surface of the cylindrical body as a solid.

According to the present invention, the purge gas near the fiber periphery has a high flow rate because the diameter of the cylindrical body 6 is extremely small, and the mist and volatile components in the purge gas are cooled and attached to the inner surface of the cylindrical body 6. Previously, it is discharged to the outside of the light irradiation device 11 together with the purge gas.

Therefore, according to the device using the small-diameter cylindrical body 6 of the present invention, the light from the light irradiation lamp 5 is not attenuated by being absorbed by the deposits on the inner surface of the cylindrical body 6. Further, the curing ability does not decrease, and there are no problems in increasing the linear speed or in continuous operation over a long period of time. Furthermore, the apparatus for carrying out the present invention is simple and requires almost no maintenance.

[0015]

EXAMPLES The present invention will be specifically explained with the following examples, but these are not intended to limit the scope of the invention.

Example 1 In an optical fiber manufacturing apparatus as shown in FIG. 1, nitrogen gas was flowed into the inner wall of a cylindrical body 6 made of a quartz tube with an outer diameter of 13 mm and an inner diameter of 10 mm at a flow rate of 10 L/min.

[0016] As a result, two layers of urethane acrylate resin were applied in sequence, and while curing, the resin was applied at a linear speed of 200 m/min.
The line was drawn continuously for 0 hours. After drawing, the inner surface of the cylindrical body 6 of the light irradiation device 11 was examined, and there was almost no mist generated from the resin or attachment of volatile components. Furthermore, when the degree of curing of the coating resin of the fiber obtained by drawing was examined, it was found that the entire length was completely cured.

[0017]

Example 2 In an optical fiber manufacturing apparatus as shown in FIG. 1, a quartz tube having the same diameter as in Example 1 was used, and argon gas was introduced at a flow rate of 10 L/min. Thereby, two layers of urethane acrylate resin were sequentially applied, and while curing the resin was drawn continuously at a drawing speed of 200 m/min for 10 hours. As in Example 1, there was no resin adhesion to the inner surface of the cylindrical body 6, and it was found that the fiber coating was completely cured over the entire length.

[0018]

[Comparative Example 1] In an optical fiber manufacturing apparatus as shown in FIG. 1, a quartz tube having the same diameter as in Example 1 was used, and nitrogen gas was introduced at a flow rate of 5 L/min. As a result, two layers of urethane acrylate resin are sequentially applied, and while curing, the line speed is 20.
The wire was drawn continuously for 10 hours at 0 m/min. Cylindrical body 6 after drawing
When we examined the inner surface, we found that a resin component had adhered to it, making it difficult for ultraviolet rays to pass through. Furthermore, it was found that the coating of about 1/3 of the obtained optical fiber was not completely cured.

[0019]

[Comparative Example 2] In an optical fiber manufacturing apparatus as shown in FIG. 1, nitrogen gas was introduced at a flow rate of 10 L/min using a quartz tube having an inner diameter of 20 mm and an outer diameter of 23 mm. Thereby, two layers of urethane acrylate resin were sequentially applied, and while curing the resin was drawn continuously at a drawing speed of 200 m/min for 10 hours. When the inner surface of the cylindrical body was examined after drawing, it was found that resin components had adhered to it, making it difficult for ultraviolet rays to pass through. It was also found that the coating of about 1/2 of the obtained optical fibers was not completely cured.

[0020]

[Effects of the Invention] According to the optical fiber manufacturing apparatus and optical fiber manufacturing method using the same of the present invention, there is no generation of adhering mist or volatile matter on the inner surface of the cylindrical body 6 or accumulation of mist inside the cylindrical body 6. Therefore, light absorption due to this is difficult to occur, and the light intensity can be maintained high and for a long time. Therefore, the curing speed increases, the linear speed can be improved, and there is no problem in long-term operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a state in which the inner diameter of the cylindrical body 6 in the ultraviolet irradiation device 11 is set to 10 mm or less when the photocurable resin coated on the optical fiber 3 is cured by passing it through the ultraviolet irradiation device 11. It is a diagram.

FIG. 2 is a schematic diagram showing a conventional optical fiber manufacturing apparatus and an optical fiber manufacturing method using the same.

[Explanation of symbols]

1 Optical fiber base material 2　Drawing furnace 3 Optical fiber 4 Resin coating equipment 5 Light irradiation lamp 6 Cylindrical body 7 Resin coated optical fiber 8 Winder 9 Gas supply pipe 10 Reflector 11. Light irradiation device 12 Cylindrical body with an inner diameter of 10 mm or less

Claims (2)

[Claims] Claim 1: After coating an optical fiber with a photocurable resin, the optical fiber is passed through a light-transmitting cylindrical body, and light is irradiated from the outer periphery of the cylindrical body to cure the photocurable resin. In the method of manufacturing an optical fiber forming a coating, a light irradiation device is used in which the inner diameter of the light-transmitting cylindrical body is 10 mm or less, and the flow rate of the inert gas flowing into the light-transmitting cylindrical body is 10 L/min. A method for manufacturing an optical fiber, characterized by the above. 2. After coating an optical fiber with a photocurable resin, the optical fiber is passed through a light-transmitting cylindrical body, and light is irradiated from the outer periphery of the cylindrical body to cure the photocurable resin. In the light irradiation device that forms the coating, the inner diameter of the light-transmitting cylindrical body is set to 10
A light irradiation device characterized by having a small diameter of less than mm.