JPH1045436A - Uv curing device for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a UV curing device for optical fibers which prohibits the infiltration of oxygen into a curing furnace accompanying the introduction of the optical fibers and is made sufficiently adaptable to high-speed take-up in particular. SOLUTION: This UV curing device 4 cures UV curing type resins for coating the optical fibers 2. In such a case, the device has the curing furnace 6 which has a UV transparent pipe 8 for allowing the passage therein of the optical fibers 2 continuously delivered from a delivery means 1 and coated with the UV curing type resins and a UV irradiation lamp 7 arranged to face this UV transparent pipe 8 and an introducing pipe 15 which is disposed in continuation with the end of the UV transparent pipe 8 on the side to be introduced with the optical fibers 2 and is used to guide the optical fibers 2 to the inside of the curing furnace 6. Branch pipes 9, 16 for blowing inert gases are connected to the UV transparent pipe 8 and the introducing pipe 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet curing device for curing an ultraviolet curable resin coated on an outer peripheral surface of an optical fiber, and more particularly to a device which reduces tackiness on the surface of the coated resin during high-speed winding. About.

[0002]

2. Description of the Related Art As a method for forming a resin coating on an optical fiber, a bare optical fiber or an already coated optical fiber is passed through a coating die to apply an ultraviolet curable resin to the outer peripheral surface of the optical fiber. A method of coating and then irradiating with ultraviolet rays to cure and then wind up is generally employed. In a state in which a large number of optical fiber strands are bundled in a planar shape, an ultraviolet curable resin is applied to the outer peripheral surface thereof, and the resin is cured to be wound into a tape while being integrated.

However, the inside of an ultraviolet curing furnace for irradiating ultraviolet rays is exposed to a considerably high temperature due to heat of an ultraviolet lamp, and the cured surface of the resin is easily damaged. You need to keep it lower. In addition, when outside air is present at a location irradiated with ultraviolet rays, the curing of the resin surface layer becomes insufficient, and the coated surface of the obtained product may be sticky and surface tackiness may occur. It is believed that this is due to the radical scavenging action of oxygen in the air. In other words, the photoinitiator contained in the ultraviolet curable resin is cleaved into radical molecules by ultraviolet irradiation and reacts with the monomer. However, when oxygen in the air is present near the radical molecule, the generated radical molecule becomes a resin monomer. It reacts more with oxygen than it does, and as a result, the curing reaction of the resin does not occur.

[0004] For the above reasons, an optical fiber resin coating forming apparatus provided with an ultraviolet curing apparatus as shown in FIG. 2 has been conventionally used. In the figure, a number of optical fiber wires 2 fed from a number of feed reels 1 are connected to a resin coating device 3.
At the same time, it becomes an uncured optical fiber tape 2a whose outer peripheral surface is coated with an ultraviolet-curing resin, and passes through the optical fiber tape 2a through an ultraviolet-curing device 4. Then, the resin-coated optical fiber tape 2b is formed by curing the resin by irradiating ultraviolet rays.

Here, the ultraviolet curing device 4 comprises a curing furnace 6
And an ultraviolet irradiation lamp 7 disposed on one inner side of the curing furnace 6 so as to face the optical fiber tape 2a along the passing direction.
And a cylindrical ultraviolet transmitting tube 8 having opposite ends opened to allow the optical fiber tape 2a to pass therethrough. A branch pipe 9 penetrating through the curing furnace 6 and communicating therewith is provided on one side of the ultraviolet transmission tube 8 on the inlet side, and the branch pipe 9 has an inert gas supplied from an inert gas supply source 10. Are connected.

An oxygen sensor 12 having a detection end protruding into the ultraviolet ray transmitting tube 8 is disposed on the other side of the ultraviolet ray transmitting tube 8 on the outlet side. Has been detected. The detection output of the sensor 12 is input to the control device 13. The control device 13 automatically controls the opening degree of the flow regulator 11 according to the detection output from the sensor 12, and the inert gas flows into the ultraviolet ray transmitting tube 8 at a flow rate corresponding to the control amount, and is hardened. While replacing the oxygen existing in the furnace 6 to eliminate the influence of the oxygen,
The temperature inside the ultraviolet ray transmitting tube 8 is lowered, and the thermal effect of the cured resin is also eliminated.

An optical fiber coating forming apparatus disclosed in Japanese Patent Application Laid-Open No. 4-32445 has a structure similar to the above-mentioned ultraviolet curing apparatus. This apparatus comprises a coating means for coating an outer peripheral surface of an optical fiber with an ultraviolet curable resin, a curing means for irradiating ultraviolet light to an optical fiber having an outer peripheral surface coated with an ultraviolet curable resin to cure the resin, and a coating means. And a hardening means, and an oxygen concentration of 1% in the hollow body and the hardening means.
Connection means for maintaining the following atmosphere. An inert gas is fed into the cylinder, and the optical fiber passes through the cylinder. With such a configuration, similarly to the above, the influence of oxygen and the thermal influence of the heat of irradiation with ultraviolet rays are eliminated.

[0008]

However, in the conventional apparatus shown in FIG. 2, the ultraviolet ray transmitting tube 8 opens to the outside air,
Since the optical fiber tape 2a is configured to enter the curing furnace 6 from its opening, air near the surface of the optical fiber tape 2a is entrained as the optical fiber tape 2a enters the ultraviolet transmitting tube 8. It will penetrate into the ultraviolet transmission tube 8. Such air entrainment increases as the penetration speed of the optical fiber tape 2a into the curing furnace 6, that is, the winding speed by the winding reel 5, increases. In order to increase the productivity, it is necessary to increase the winding speed, but the influence of oxygen as described above increases. In order to increase the productivity, it is effective to use a more curable ultraviolet-curable resin, but such a resin is generally expensive and increases the cost.

Further, in the same device, the oxygen sensor 12
Indicates that the oxygen concentration in the ultraviolet ray transmitting tube 8 is detected, but the oxygen concentration at the irradiation position where the curing reaction is actually performed is not detected. It is difficult to say that the oxygen concentration of the oxygen is reliably captured. Such control of the oxygen concentration at the reaction site is important for complete curing, especially in high-speed winding. A similar problem is also encountered in the apparatus described in JP-A-4-3244, in which the actual oxygen concentration in the curing reaction portion is not controlled.

As described above, in the conventional apparatus, when the linear speed is increased and winding is performed at a high speed, an increase in the oxygen concentration in the curing furnace due to the entrained air is inevitable. In addition to lowering the yield, it was difficult to say that the control of the flow rate of the inert gas by the control device was properly performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent air from entering into a curing furnace when an optical fiber coated with an ultraviolet curing resin is introduced into the curing furnace. An object of the present invention is to provide an ultraviolet curing device for an optical fiber, which prevents the curing of the resin and improves the curing of the resin.

[0012]

In order to achieve the above object, an ultraviolet curing apparatus for an optical fiber according to the present invention comprises an optical fiber which is continuously fed from a feeding means and coated with an ultraviolet curing resin. A curing furnace having an ultraviolet transmitting tube to be passed through and an ultraviolet irradiation lamp arranged to face the ultraviolet transmitting tube; and a curing furnace provided continuously to an introduction side end of an optical fiber of the ultraviolet transmitting tube, the optical fiber being placed inside the curing furnace. And a branch pipe for blowing an inert gas is connected to the ultraviolet transmitting pipe and the introducing pipe. Further, in the above configuration, furthermore, there is further provided a linear velocity measuring means for the optical fiber, and a control for adjusting the flow rate of the inert gas blown through the branch pipe connected to the introduction pipe according to the measurement result of the measuring means. Preferably, means are provided.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition,
The same portions as those in the related art are denoted by the same reference numerals, and description will be made using different reference numerals only for different portions or newly added portions.

FIG. 1 is a schematic structural view showing an embodiment of an ultraviolet curing device for an optical fiber according to the present invention. In FIG. 1, a large number of optical fiber wires 2 fed from a large number of feed reels 1 pass through a resin coating device 3,
An uncured optical fiber tape 2a whose outer peripheral surface is coated with an ultraviolet-curable resin at the same time as being arranged on one surface in a flat state, and this optical fiber tape 2a is passed through an ultraviolet-curing device 4 to be irradiated with ultraviolet light The optical fiber tape 2b is formed by curing the resin, and is wound on a winding reel 5 disposed outside the outlet of the ultraviolet curing device 4.

The ultraviolet curing apparatus 4 according to the present invention is, similarly to the conventional one, a curing furnace 6 and an ultraviolet irradiation apparatus which is disposed on one side inside the curing furnace 6 so as to face the optical fiber tape 2a in the direction in which the optical fiber tape 2a passes. The apparatus includes a lamp 7 and a cylindrical ultraviolet transmitting tube 8 disposed opposite to the ultraviolet irradiation lamp 7 and having both ends opened to allow the optical fiber tape 2a to pass therethrough. A branch pipe 9 that penetrates through the curing furnace 6 and communicates therewith is integrally provided on one side of the ultraviolet transmission pipe 8. The branch pipe 9 is supplied from an inert gas supply source 10. An inert gas flow controller 11 is connected. The ultraviolet transmission tube 8 is
The tube is made of a transparent material having a high ultraviolet transmittance and heat resistance, and is made of, for example, heat resistant glass, preferably quartz. An oxygen sensor 12 having a detection end protruding into the ultraviolet transmission tube 8 is disposed near the exit side of the ultraviolet transmission tube 8 to detect the oxygen concentration in the atmosphere gas in the ultraviolet transmission tube 8. . Then, based on the detection result of the oxygen sensor 12, the opening degree of the flow regulator 11 is adjusted by the control device 13.

In addition to the above structure, the ultraviolet curing device 4 of the present invention comprises:
That is, the hollow introduction pipe 1 is connected to the end of the resin coating device 3 side.
5 are provided. The introduction tube 15 may be formed integrally as an extension of the ultraviolet transmission tube 8 or may be joined to the ultraviolet transmission tube 8 as a separate member. When joining, it is necessary to completely seal both joints. Further, even if this introduction tube 15 is formed as a separate member, heat from the ultraviolet transmission tube 8 is conducted, so that a certain degree of heat resistance is required. Therefore, it is preferable to use quartz made of excellent heat resistance, similarly to the ultraviolet transmission tube 8. In addition, the introduction pipe 15
A branch pipe 16 communicating with the inside of the optical fiber 2a is integrally connected to the leading end of the optical fiber 2a. This branch pipe 16
Is connected to the inert gas supply source 10 via the flow control valve 17. Although the branch pipe 16 may be single, for example, in the production of an optical fiber tape, it is preferable to make a pair so as to supply an inert gas from both sides of the tape as shown in the figure.

Further, a linear speed measuring sensor 18 is connected to the take-up reel 5 to detect the winding speed of the optical fiber tape 2b, and the result of the detection is constantly monitored by the control device 13 to control the linear speed. Control is performed to increase or decrease the opening of the flow control valve 17 of the branch pipe 16 in accordance with the increase or decrease. That is, as the winding speed of the take-up reel 5 increases, the amount of outside air involved also increases. Therefore, by increasing the opening degree of the flow control valve 17 and increasing the amount of inert gas flowing in, the outside air Inflow can be completely blocked. Here, the relationship between the winding speed and the entrainment amount of the outside air accompanying the winding speed is determined in advance by an experiment, and based on the data, the opening degree of the flow rate control valve 17 is adjusted to the optimum value, so that the necessary minimum inert gas The inflow of outside air can be blocked with a certain amount.

As described above, since the inflow of the outside air is completely shut off in the introduction pipe 15, the curing reaction in the curing furnace 6 is performed extremely well, and the resin coating having no tack and having excellent surface properties is obtained. The optical fiber tape 2b is obtained.

[0019]

As is clear from the above description, the ultraviolet curing apparatus for optical fibers according to the present invention is capable of preventing the external air from being entrained by the introduction of the optical fibers into the curing furnace. Since the outside air is blocked before, the curing reaction by the ultraviolet rays in the curing furnace is favorably performed, and a high-quality resin-coated optical fiber can be obtained. In addition, even when the linear velocity of the optical fiber is increased, entrainment of outside air can be completely shut off, and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an ultraviolet curing device according to the present invention.

FIG. 2 is a schematic view showing the configuration of a conventional ultraviolet curing device.

[Explanation of symbols]

 Reference Signs List 2 optical fiber 2a, 2b optical fiber tape 3 resin coating device 4 ultraviolet curing device 5 take-up reel 7 ultraviolet irradiation lamp 8 ultraviolet transmission tube 10 inert gas supply source 13 control device 15 introduction tube 16 branch tube 17 flow control valve 18 Linear velocity measurement sensor

Claims (2)

[Claims] 1. An ultraviolet curing device for curing an ultraviolet curing resin coating an optical fiber, wherein the ultraviolet curing device is continuously fed from a feeding means and passes through the optical fiber coated with the ultraviolet curing resin therein. A curing furnace having an ultraviolet transmission tube to be made and an ultraviolet irradiation lamp disposed opposite to the ultraviolet transmission tube; and a curing furnace provided continuously with an introduction side end of the optical fiber of the ultraviolet transmission tube to guide the optical fiber into the curing furnace. And an introduction pipe for
An ultraviolet curing apparatus for an optical fiber, wherein a branch pipe for blowing an inert gas is connected to an ultraviolet transmission pipe and an introduction pipe. And a control means for adjusting a flow rate of the inert gas blown through a branch pipe connected to the introduction pipe according to a measurement result of the measuring means. The ultraviolet curing device for an optical fiber according to claim 1, wherein: