JP2000005694A - Method for coating ultraviolet-curable resin on linear body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a clouding from occurring on an ultraviolet-curing cylindrical body consisting of a quartz tube or the like and thereby decrease the replacement frequency of the cylindrical body by coating titanium dioxide on the inner face of an ultraviolet-transmitting cylindrical body through which a linear body coated with an ultraviolet-curable resin passes. SOLUTION: Ultravilet rays emitted from an ultraviolet rays bulb 4 are made to reflect by a reflector 3 to be emitted to an ultraviolet-curing cylindrical body 2 in a curing device 1, so that an ultraviolet-curable resin applied to an optical fiber 10 passing through the interior of the cylindrical body 2, is cured. In this case, an inert gas is purged through the ultraviolet-curing cylindrical body 2 by regulating the flow rate with the help of a flow rate regulator 8 to create a mixed gas atmosphere of air and the inert gas. Further a shutter 7 is arranged at the inlet 5 and the outlet 6 of the curing device 1 to regulate the internal oxygen concentration of the ultraviolet- curing cylindrical body 2. Besides a titanium dioxide is applied to the inner face of the cylindrical body 2 and at the same time, the oxygen concentration in the cylindrical body 2 is set at 0.1 or more and below the oxygen concentration of an atmosphere and then ultraviolet rays are emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for coating a linear body with an ultraviolet curable resin.

[0002]

2. Description of the Related Art Conventionally, optical fiber core wires, electric wires, steel wires,
A linear body such as a string or a rope, a tape-like linear body in which these are arranged in a tape shape (for example, an optical fiber tape core wire), or a tape of various plastics or metals (hereinafter, collectively referred to as a linear body) Is coated with an ultraviolet curable resin,
Filling the coating device with an ultraviolet-curable resin adjusted to a predetermined viscosity, applying the ultraviolet-curable resin to the linear body by passing the linear device through the coating device, and irradiating the ultraviolet-curable resin with ultraviolet light. It is performed by a method of curing the ultraviolet curable resin.

As a method of curing an ultraviolet curable resin, for example, a method described in Japanese Patent Publication No. 6-84015 can be mentioned. This method will be described with reference to FIG. 5. A quartz tube 18 is arranged as a cylindrical body that transmits ultraviolet light (hereinafter, referred to as an ultraviolet transmitting cylindrical body) in the curing device 1, and a line coated with an ultraviolet curable resin is provided. The linear body 21 is allowed to pass through the quartz tube 18 and ultraviolet rays are irradiated from the ultraviolet bulb 4 outside the quartz tube to the ultraviolet curable resin applied to the linear body to cure the ultraviolet curable resin. Was. At this time, the inert gas whose flow rate was controlled by the flow control valve 20 was purged into the quartz tube 18, and the gas in the quartz tube 18 was exhausted by the suction pump 9 at the same time. Despite this, a part of the ultraviolet curable resin is volatilized and adheres to the quartz tube 18, so that the cloudiness of the quartz tube 18 increases as the operation proceeds, and the ultraviolet transmittance of the quartz tube decreases. As a result, the amount of ultraviolet light reaching the linear body is reduced, so that the degree of curing of the ultraviolet curable resin is reduced, and eventually quality problems occur.

[0004] In order to avoid this problem, the amount of ultraviolet light transmitted through the quartz tube is measured, and when the amount of ultraviolet light falls to a reference value at which the ultraviolet curable resin can be sufficiently cured, the quartz tube is cleaned without fogging. Had to be replaced. Actually, when the coating of one linear body with the UV-curable resin is completed, the amount of ultraviolet light that passes through the quartz tube is measured, and the amount of UV light that has passed through the quartz tube during the next UV-curable resin coating work on the linear body is measured. When it is expected that the amount of ultraviolet light to be used will be insufficient, the quartz tube has been replaced.

Japanese Patent Application Laid-Open No. 10-59749 discloses that the inner surface of a quartz tube is coated with titanium dioxide so that the ultraviolet curing resin hardly adheres to the quartz tube.

[0006]

However, the inventor of the present invention has disclosed that although the inner surface of a quartz tube is coated with titanium dioxide as disclosed in Japanese Patent Application Laid-Open No. 10-59749, the quartz tube is made of an ultraviolet curable resin. Cloudy components adhere,
Still experienced that the frequency of quartz tube replacement did not decrease. That is, it was found that simply coating the inner surface of the quartz tube with titanium dioxide was not sufficient. According to the present invention, an ultraviolet-curable resin is applied to a linear body, and then the ultraviolet-transparent cylindrical body disposed in a curing device is passed through the linear body, and ultraviolet rays are cured from outside the ultraviolet-permeable cylindrical body. It is an object of the present invention to provide a method of coating a linear body with an ultraviolet-curable resin, which can reduce the amount of a fogging component derived from the ultraviolet-curable resin adhered to a quartz tube when the resin is irradiated to cure the ultraviolet-curable resin. And

[0007]

SUMMARY OF THE INVENTION According to the present invention, an ultraviolet curable resin is applied to a linear body, and then an ultraviolet transmitting cylindrical body arranged in a curing device is passed through the linear body to transmit ultraviolet rays. In the method of irradiating the ultraviolet-curable resin from outside the cylindrical body to cure the ultraviolet-curable resin and coating the linear body with the ultraviolet-curable resin, the ultraviolet-transparent cylindrical body is coated with titanium dioxide on the inner surface. A method for coating a linear body with an ultraviolet curable resin, wherein the ultraviolet ray is irradiated with the oxygen concentration in the ultraviolet transmitting cylindrical body being 0.1% or more and less than the oxygen concentration in the atmosphere. .

[0008] In the above method, the oxygen concentration in the ultraviolet transmitting cylinder is reduced to 0.1 by purging a mixed gas of an inert gas and air or oxygen into the ultraviolet transmitting cylinder.
% Or more and less than the oxygen concentration in the atmosphere.

The oxygen concentration in the quartz tube is more preferably 0.5% or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention has proposed that coating titanium dioxide on an ultraviolet-transparent cylindrical body itself does not prevent adhesion of an ultraviolet-curable resin, but coats titanium dioxide on the inner surface of the ultraviolet-permeable cylindrical body. In addition, they have found that it is necessary to make the oxygen concentration in the ultraviolet transmitting cylindrical body 0.1% or more, and completed the present invention.

In the present invention, when the oxygen concentration in the ultraviolet ray transmitting cylindrical body is 0.1% or more, it is possible to reduce the adhesion of the fogging component to the ultraviolet ray transmitting cylindrical body. When the content is 0.5% or more, adhesion of the fogging component to the ultraviolet transmitting cylindrical body can be significantly reduced. Further, when the oxygen concentration in the ultraviolet ray transmitting cylindrical body is set to 2% or more, it is possible to almost completely prevent the fogging component from adhering to the ultraviolet ray transmitting cylindrical body. In addition,
The oxygen concentration is preferably lower than the oxygen concentration in the air from the viewpoint of preventing oxidation of the ultraviolet curable resin.

Since the rate of adhesion of the fogging component to the ultraviolet-transmitting cylindrical body varies depending on the type and composition of the ultraviolet-curable resin, it is preferable to select an oxygen concentration appropriate for the type and composition of the ultraviolet-curable resin.

The oxygen concentration in the ultraviolet transmitting cylindrical body is as follows:
Since the degree of cure of the ultraviolet curable resin is affected, it is preferable to select an appropriate oxygen concentration to satisfy the required degree of cure depending on the use of the linear body. When the optical fiber is coated with an ultraviolet curable resin, the cured state of the surface of the ultraviolet curable resin does not pose a quality problem if the oxygen concentration is 5% or less.

When an ultraviolet curable resin for coloring is cured on an optical fiber in which an optical fiber is coated with an ultraviolet curable resin, if the oxygen concentration in the ultraviolet transmitting cylindrical body is more than 1%, a coloring book is formed. The surface of the ultraviolet-curable resin becomes uncured, and the strength of adhesion to the ultraviolet-curable resin for a tape when the optical fiber ribbon is formed in a later step becomes too strong. Therefore, when the optical fiber ribbon is separated into single fibers, not only the ultraviolet curing resin for the optical fiber ribbon but also the ultraviolet curing resin layer for coloring is peeled off, and the color of the core cannot be identified by the color. Occurs. Therefore, when the optical fiber is coated with the ultraviolet curing resin for coloring, the oxygen concentration is preferably 1% or less.

A linear body obtained by coloring the optical fiber is called an optical fiber core. A plurality of optical fiber cores arranged and collectively covered is called an optical fiber tape core. 5 when curing the ultraviolet curing resin for optical fiber ribbon
If the oxygen concentration exceeds%, the surface of the ultraviolet curable resin becomes uncured, and the optical fiber ribbons stick together while being wound on a bobbin. Then, when the optical fiber ribbon is fed from the bobbin, the attached portion is pulled, and the ultraviolet curable resin for the tape and the ultraviolet curable resin for coloring adhered thereto are separated. Occurs. Therefore, when a plurality of optical fiber cores are collectively coated with the ultraviolet curable resin, the oxygen concentration is preferably 5% or less.

In the present invention, the coating method of titanium dioxide is a method of mixing and coating titanium dioxide in an organic solvent, followed by baking, spraying titanium dioxide, flame deposition of titanium halide, hydrolysis of organic titanium compound. There is a deposition sintering method.

Titanium dioxide has a property of absorbing near-ultraviolet rays, and specifically absorbs ultraviolet rays having a wavelength shorter than 400 nm. Ultraviolet rays irradiated for curing the ultraviolet curable resin are also near ultraviolet rays. Therefore, if titanium dioxide is coated too thick, the amount of ultraviolet rays transmitted through the ultraviolet transmissive cylindrical body is reduced, and the curing of the ultraviolet curable resin becomes insufficient. Therefore, it is preferable to coat titanium dioxide as thinly as possible within a range where a sufficient catalytic action can be obtained. Specifically, it is preferable to coat with a thickness of 0.5 μm or less.

The method for coating a linear body with an ultraviolet curable resin according to the present invention will be described below with reference to FIG. The optical fiber preform 11 is heated by a drawing furnace 12 and pulled by a capstan or the like (not shown) to reduce the diameter to a predetermined outer diameter to obtain an optical fiber 10.
After cooling, the coating device 14 applies an ultraviolet curing resin to the optical fiber 10, and the curing device 1 further cures the ultraviolet curing resin. In this way, the optical fiber coated with the ultraviolet curable resin, that is, the optical fiber 15 is manufactured, and the optical fiber 15 is wound by the winder 16.

The control of the oxygen concentration in the ultraviolet transmitting cylindrical body will be described below with reference to FIG. 3 by taking as an example the case of curing the ultraviolet curing resin applied to the optical fiber. In the curing device 1, an ultraviolet transmitting cylindrical body 2 and an ultraviolet bulb 4 are provided.
Is arranged. The ultraviolet transmitting cylindrical body 2 is disposed at a position where the optical fiber 10 passes through the central axis. A reflecting mirror 3 is arranged around the ultraviolet transmitting cylindrical body 2 and the ultraviolet bulb 4 so as to surround them. Since the ultraviolet ray transmitting cylindrical body 2 and the ultraviolet ray bulb 4 are arranged so as to be located at the focal point of the reflecting mirror 3, the ultraviolet rays emitted from the ultraviolet ray bulb 4 are reflected by the reflecting mirror 3 to efficiently emit the ultraviolet ray transmitting cylinder. Irradiated to the state body 2.

The inert gas is purged into the ultraviolet transmitting cylindrical body 2 by adjusting the flow rate by the flow rate controller 8. Since the inside of the ultraviolet ray transmitting cylindrical body 2 communicates with the air through the inlet 5 or the outlet 6, the inert gas is purged inside the ultraviolet ray transmitting cylindrical body 2 so that the atmosphere of the mixed gas atmosphere of the air and the inert gas is formed. Become. As the flow rate of the inert gas increases, the concentration of the inert gas in the ultraviolet transmitting cylindrical body 2 increases, and the oxygen concentration decreases. The inert gas is preferably N ₂ in terms of cost.

The relationship between the flow rate of the inert gas and the oxygen concentration may be determined in advance, and the inert gas having a desired oxygen concentration may be purged. In addition, an oxygen concentration sensor is disposed in the ultraviolet transmitting cylinder, a signal from the sensor is sent to a feedback control device, and a purge amount of an inert gas is adjusted by the feedback control device, so that the ultraviolet transmitting cylinder has a desired inside. The oxygen concentration can be adjusted.

The oxygen concentration in the ultraviolet transmitting cylindrical body 2 can be controlled by providing a shutter 7 at the inlet 5 or the outlet 6 of the curing device 1 and adjusting the opening thereof. When the opening of the shutter 7 is reduced, the oxygen concentration in the ultraviolet transmitting cylindrical body decreases.

The relationship between the opening degree of the shutter and the oxygen concentration may be determined in advance, and the opening degree of the shutter may be adjusted so as to obtain a desired oxygen concentration. In addition, an oxygen concentration sensor is disposed in the ultraviolet transmitting cylinder, a signal of the sensor is sent to a feedback control device, and the opening degree of the shutter is adjusted by the feedback control device to obtain a desired oxygen concentration in the ultraviolet transmitting cylindrical body. It can also be

Further, by providing the suction pump 9 in the exhaust system and actively exhausting the gas in the ultraviolet transmitting cylinder, the oxygen concentration in the ultraviolet transmitting cylinder can be adjusted.

It should be noted that the oxygen concentration in the ultraviolet transmitting cylindrical body sometimes depends on the linear velocity of the optical fiber. For example, the flow rate of purging the inert gas into the ultraviolet transmitting cylindrical body 2 is 20 seconds.
If it is lm, the higher the linear velocity, the higher the oxygen concentration in the ultraviolet transmitting cylindrical body. Inert gas flow rate is 40 slm
To the extent, there is not much dependence of the oxygen concentration in the ultraviolet transparent cylinder on the linear velocity. Therefore, when the inert gas purge amount is relatively small, it is preferable that the oxygen concentration in the ultraviolet transmitting cylindrical body in the steady state after the linear velocity rises has a value within the above range.

By comprehensively adjusting each of the above factors, it is possible to control the oxygen concentration in the ultraviolet transmitting cylindrical body to a desired value.

Also, oxygen and an inert gas may be mixed in advance, and a mixed gas adjusted to a target oxygen concentration may be purged into the ultraviolet transmitting cylindrical body. However, it should be noted that, at this time, due to the influence of the linear velocity, the oxygen concentration in the ultraviolet transmitting cylindrical body may be different from the oxygen concentration to be purged.

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. 1. Coating of titanium dioxide Fine powder of titanium dioxide (TiO ₂ ) having a particle size of 30 nm or less is added to polysilazane (-(SiH ₂ NH)-) at a weight ratio of 1:
1 and diluted with xylene. This mixed solution was poured into the inner surface of the quartz tube and applied. This quartz tube is 450 ± 5
Firing at 0 ° C., 0.5 μm thick TiO 2
_Two coating layers were formed. The thickness of the titanium dioxide layer to be coated was adjusted by adjusting the dilution with xylene.

2. Coating of Optical Fiber In the optical fiber element manufacturing apparatus shown in FIG. 2, an ultraviolet curing resin (urethane acrylate resin) is applied to the optical fiber 10 by the coating device 14, and further, the curing device 1 is used.
To cure the ultraviolet curable resin. The UV-curable resin used had a viscosity at 40 ° C. (temperature at the time of application) of 1,000 to 2,000 cp. The optical fiber coated with the ultraviolet curable resin, that is, the optical fiber 15
And the optical fiber 15 was wound up by a winder 16. The winding speed (linear speed) at this time is 800 m /
Minutes.

FIG. 4 shows the configuration of the curing device at this time.
The quartz tube 18 coated on the inner surface with the TiO ₂ layer 17 by the above-mentioned coating method was disposed in the curing device 1 as an ultraviolet transmitting cylindrical body. In FIG. 4, portions common to FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. Nitrogen was used as the inert gas. Nitrogen and air flow controllers 8
The flow rate is adjusted at a and 8b, and the mixture is discharged.
And sent into the ultraviolet curing device 1 via the flow path, and purged into the quartz tube 18.

The flow rate of nitrogen and the flow rate of air were adjusted as shown in Table 1 so that the oxygen concentration in the quartz tube 18 was 0.01% (1%).
00 ppm), 0.10%, 1.00% or 2.00
%. In each case, a shutter 7 was provided at the inlet 5 and the outlet 6 of the curing device 1 and their diameter was 6 mm. Also, 40 sl by the suction pump 9
m was evacuated. In these three cases, coating of the optical fiber with an ultraviolet curable resin was performed.

[0032]

[Table 1]

As a control experiment, an optical fiber was coated with an ultraviolet curable resin in the same manner as described above using a quartz tube not coated with TiO ₂ as an ultraviolet transmitting cylindrical body.

In each of the above cases, the amount of ultraviolet light transmitted through the ultraviolet transmitting cylindrical body was measured using an ultraviolet light amount measuring device. FIG. 1 shows the change with time in the amount of ultraviolet light transmitted through the ultraviolet transmitting cylindrical body. In FIG. 1, the numerical value on the vertical axis is 100 km
Is a relative value in which the amount of ultraviolet light transmitted through the quartz tube when the optical fiber is coated is represented as 1, and the amount of ultraviolet light transmitted through the quartz tube at a time when the quartz tube is not clouded before the start of coating. Table 2 shows the amount of ultraviolet light transmitted through the TiO ₂ -coated quartz tube and the uncoated quartz tube at a drawing time of 500 minutes.

[0035]

[Table 2]

From FIG. 1 and Table 2, it was found that when the oxygen concentration in the quartz tube was 0.01% or less, the effect of TiO ₂ hardly appeared. On the other hand, it has been found that when the oxygen concentration is 0.01% or more, the adhesion of the fogging component derived from the ultraviolet curable resin to the quartz tube can be reduced by applying the TiO ₂ coating. Further, when the oxygen concentration was 2% or more, the adhesion of the fogging component to the quartz tube could be completely prevented, and no decrease in the ultraviolet transmittance was observed. That is, T
It was found that the active oxygen generated by the catalytic action of iO ₂ effectively removed the fogging component derived from the ultraviolet curable resin adhered to the inner surface of the quartz tube.

[0037]

According to the method of the present invention, titanium dioxide is coated on the inner surface of the ultraviolet ray transmitting cylindrical body in the curing device, and the ultraviolet ray transmitting cylindrical body is brought to a predetermined oxygen concentration, whereby the ultraviolet ray transmitting cylinder has a predetermined oxygen concentration. Since the fogging of the transmission cylinder can be prevented, the frequency of replacement of the ultraviolet transmission cylinder can be reduced. In addition, since the time for one ultraviolet curing resin coating operation can be extended, a long linear body that could not be obtained conventionally can be obtained as a result of the coating operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change over time in ultraviolet transmittance.

FIG. 2 is a diagram showing a configuration of an optical fiber element manufacturing apparatus.

FIG. 3 is a diagram showing a configuration of a curing device.

FIG. 4 is a diagram showing a configuration of a curing device.

FIG. 5 is a diagram showing a configuration of a conventional curing device.

[Explanation of symbols]

1: Curing device 2: Ultraviolet transmitting cylinder 3: Reflecting mirror 4: Ultraviolet valve 5: Inlet 6: Outlet 7: Shutter 8: Flow controller 8a: Flow controller 8b: Flow controller 9: Suction pump 10: Light Fiber 11: Optical fiber preform 12: Drawing furnace 13: Cooling device 14: Coating device 15: Optical fiber strand 16: Winder 17: TiO ₂ layer 18: Quartz tube 19: Mixing point 20: Flow control valve 21 : Linear body

Continued on the front page (72) Inventor Ichiro Tsuchiya 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa F-term (reference) in Yokohama Works, Sumitomo Electric Industries, Ltd. 4D075 BB42Y BB46Y BB52Y BB54Y BB57Y CB06 DA01 DC24 EA21 EB22 EB38 EC02 EC45

Claims (2)

[Claims] 1. After applying an ultraviolet curable resin to a linear body,
An ultraviolet ray transmitting cylindrical body disposed in a curing device is passed through the linear body, and ultraviolet rays are irradiated on the ultraviolet curing resin from outside the ultraviolet transmitting cylindrical body to cure the ultraviolet curing resin, thereby forming a linear shape. In the method of coating the body with an ultraviolet-curable resin, the ultraviolet-transmitting cylindrical body used is one coated with titanium dioxide on the inner surface, and the oxygen concentration in the ultraviolet-transmitting cylindrical body is 0.1% or more. A method of coating a linear body with an ultraviolet curable resin, wherein the linear body is irradiated with ultraviolet light at a lower oxygen concentration. 2. A method for coating a linear body with an ultraviolet curable resin according to claim 1, wherein a mixed gas of an inert gas and air or oxygen is purged into the ultraviolet transmitting cylindrical body. A method of coating a state body with an ultraviolet curable resin.