JP2023083734A - Method for manufacturing optical fiber - Google Patents

Abstract

To provide a method for manufacturing an optical fiber which can reduce a used amount of a coating resin.SOLUTION: A method for manufacturing an optical fiber includes introducing a glass fiber formed by drawing an optical fiber base material while heating and melting into a resin coating device filled with a resin, coating a resin to the periphery of the glass fiber, then subjecting the resin coated to the periphery of the glass fiber to curing treatment and curing the resin, and thereby manufacturing an optical fiber where a coating resin layer is formed in the periphery of the glass fiber. The manufacturing method includes a step of performing drawing for taking up an optical fiber by a take-up device, a liner viscosity increase step of performing drawing while increasing linear viscosity of drawing up to linear viscosity at the time of stationary drawing, after drawing and before stationary drawing, and a stationary drawing step of performing stationary drawing for taking up a product. Viscosity of the resin in the resin coating device in the linear viscosity increase step is higher than viscosity of the resin in the resin coating device in the stationary drawing step.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present disclosure relates to methods for manufacturing optical fibers.

Patent Document 1 describes a technique to prevent disconnection in a resin coating device due to a sudden change in the line speed that occurs when the manufacturing line speed of optical fiber strands increases, such as at the time of transition from a lead-out preform to a product optical fiber preform. For the purpose of reducing this, it is disclosed to control the resin supply pressure when the line speed is increased. Specifically, in Patent Literature 1, in the section from the linear speed of the optical fiber strand to the product manufacturing linear speed while the linear speed is increasing, the increase rate of the resin supply pressure with respect to the linear speed increase rate is calculated as the product manufacturing line speed. It is smaller than the rate of increase in resin supply pressure with respect to the rate of increase in linear velocity determined by speed.

JP-A-2001-066476

The optical fiber strands manufactured during the increasing linear speed, that is, from the start of manufacturing until reaching the product manufacturing linear speed, are not used as products and are disposed of, so they are not used during the increasing linear speed. It is desirable to reduce the amount of resin to be used as much as possible. However, Patent Document 1 aims at reducing the disconnection of the optical fiber during the increase of the drawing speed, and does not aim at controlling the coating diameter during the increase of the drawing speed. The effect of reducing the amount of resin used during ascent cannot be expected.

Accordingly, an object of the present disclosure is to provide an optical fiber manufacturing method that can reduce the amount of resin used.

A method for manufacturing an optical fiber according to an aspect of the present disclosure includes:
A glass fiber formed by drawing an optical fiber preform while heating and melting it is introduced into a resin coating device filled with a resin, and after the resin is coated around the glass fiber, the glass fiber is coated. An optical fiber manufacturing method for manufacturing an optical fiber in which a coating resin layer is formed around the glass fiber by curing the resin by applying a curing treatment to the resin applied around the glass fiber,
a lead-out step of carrying out lead-out for retrieving the optical fiber with a retrieving device;
a drawing speed increasing step of performing drawing while increasing the drawing speed up to the drawing speed at the time of the steady drawing after the drawing and before the steady drawing;
a steady drawing step of performing the steady drawing of product picking;
including
The viscosity of the resin in the resin coating device in the linear speed increasing step is higher than the viscosity of the resin in the resin coating device in the steady wire drawing step.

According to the present disclosure, it is possible to provide an optical fiber manufacturing method capable of reducing the amount of resin used by reducing the amount of coating resin pulled by the glass fiber entering the resin coating device while the linear speed is increasing. can.

1 is a schematic configuration diagram of an optical fiber manufacturing apparatus according to an embodiment; FIG. 2 is a diagram showing the relationship between the drawing speed of an optical fiber and the temperature of a resin coating device provided in the optical fiber manufacturing apparatus of FIG. 1. FIG. FIG. 4 is a diagram showing the relationship between the drawing speed of the optical fiber and the temperature of the resin in the resin coating device; 2 is a cross-sectional view of an optical fiber manufactured by the optical fiber manufacturing apparatus of FIG. 1; FIG. (a) is a diagram showing the temperature control of the resin coating device in Examples 1 to 4, and (b) is the outer diameter of the optical fiber when the temperature control of the resin coating device is executed as in Examples 1 to 4. FIG. 4 is a diagram showing changes, where (c) is a diagram showing the amount of primary resin used in Examples 1 to 4, and (d) is a diagram showing the amount of secondary resin used in Examples 1 to 4. FIG.

(Description of Embodiments of the Present Disclosure)
First, the embodiments of the present disclosure are listed and described.
A method for manufacturing an optical fiber according to an aspect of the present disclosure includes:
(1) A glass fiber formed by drawing an optical fiber preform while heating and melting it is introduced into a resin coating device filled with a resin, and after the resin is applied around the glass fiber, the A method for manufacturing an optical fiber, wherein the resin coated around the glass fiber is subjected to a curing treatment to cure the resin, thereby manufacturing an optical fiber in which a coating resin layer is formed around the glass fiber. ,
a lead-out step of carrying out lead-out for retrieving the optical fiber with a retrieving device;
a drawing speed increasing step of performing drawing while increasing the drawing speed up to the drawing speed at the time of the steady drawing after the drawing and before the steady drawing;
a steady drawing step of performing the steady drawing of product picking;
including
The viscosity of the resin in the resin coating device in the linear speed increasing step is higher than the viscosity of the resin in the resin coating device in the steady wire drawing step.
According to the above method, the viscosity of the resin in the resin coating device during the linear speed increase is made higher than the viscosity of the resin in the resin coating device at the linear speed during steady wire drawing, so that the resin coating device during the linear speed increase It is possible to reduce the amount of resin pulled by the glass fiber that enters inside. As a result, the coating diameter of the optical fiber becomes thinner in the drawing speed increasing step, so that the amount of resin used from the start of the drawing step to the end of the steady drawing step can be reduced.

(2) The temperature of the resin supplied into the resin coating device in the linear speed increasing step may be lower than the temperature of the resin supplied into the resin coating device in the steady drawing step.

(3) The temperature of the resin coating device in the linear speed increasing step may be lower than the temperature of the resin coating device in the steady wire drawing step.

According to these methods, the viscosity of the resin during the increase of the drawing speed can be made higher than the viscosity of the resin during steady drawing.

(4) The temperature of the glass fiber entering the resin coating device in the drawing speed increasing step may be higher than the temperature of the glass fiber entering the resin coating device in the steady drawing step.
According to the above method, it is possible to further reduce the amount of resin pulled by the glass fiber while the drawing speed is increasing, and a further reduction in the amount of resin used can be expected.

(5) The viscosity of the resin in the resin coating device in the linear velocity increasing step may be 1 Pa·s or more.
The amount of resin used can be significantly reduced by setting the viscosity of the resin to a certain value or more while the linear velocity is increasing.

A method for manufacturing an optical fiber according to another aspect of the present disclosure includes:
(6) A glass fiber formed by drawing an optical fiber preform while heating and melting it is introduced into a resin coating device filled with a resin, and after applying the resin around the glass fiber, A method for manufacturing an optical fiber, wherein the resin coated around the glass fiber is subjected to a curing treatment to cure the resin, thereby manufacturing an optical fiber in which a coating resin layer is formed around the glass fiber. ,
a step of providing a lead for taking over the optical fiber with a take-up device;
a drawing speed increasing step of performing drawing while increasing the drawing speed up to the drawing speed at the time of the steady drawing after the drawing and before the steady drawing;
a steady drawing step of performing the steady drawing of product picking;
including
The temperature of the glass fiber entering the resin coating device in the drawing speed increasing step is higher than the temperature of the glass fiber entering the resin coating device in the steady drawing step.
According to the above method, the temperature of the glass fiber entering the resin coating device during the increase in the drawing speed is made higher than the temperature of the glass fiber entering the resin coating device during the steady drawing, thereby reducing the glass fiber during the increase in the drawing speed. It is possible to reduce the amount of resin pulled by the fiber. As a result, the coating diameter of the optical fiber becomes thinner in the drawing speed increasing step, so that the amount of resin used from the start of the drawing step to the end of the steady drawing step can be reduced.

(Details of embodiments of the present disclosure)
A specific example of an optical fiber manufacturing method according to an embodiment of the present disclosure will be described below with reference to the drawings.
The present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

FIG. 1 is a schematic configuration diagram showing an example of an optical fiber manufacturing apparatus 1 according to an embodiment of the present disclosure.
As shown in FIG. 1, an optical fiber manufacturing apparatus 1 includes a drawing furnace 10, a forced cooling device 11, a resin coating device 12, a resin supply device 13, a resin curing device 14, guide rollers 15, A take-up section 16 , a winding drum 17 , a drawing control device 18 and a temperature control device 19 are provided. The optical fiber manufacturing apparatus 1 of the present embodiment is a dual-coating type manufacturing apparatus that continuously applies the primary resin and the secondary resin and cures them all at once.

The drawing furnace 10 is configured to heat and melt the lower end portion of the optical fiber preform G with a heater. The drawing furnace 10 is an example of a heating furnace. The lower end portion of the optical fiber preform G heated in the drawing furnace 10 is thinly drawn downward, and is drawn by the tension of the take-up portion 16 to form the glass fiber G1.

A forced cooling device 11 cools the drawn glass fiber G1. The forced cooling device 11 has sufficient length along the running line to sufficiently cool the glass fiber G1. The forced cooling device 11 has, for example, an air supply port (not shown) for cooling the glass fiber G1, and cools the glass fiber G1 by introducing a cooling gas from this air supply port. For example, helium gas is used as the cooling gas. By adjusting the flow rate of the cooling gas introduced into the forced cooling device 11, the temperature of the glass fiber G1 passing through the forced cooling device 11 can be controlled.

The resin coating device 12 is provided downstream of the forced cooling device 11 in the running direction of the glass fiber G1 (direction of arrow A in FIG. 1). The resin application device 12 is configured to apply resin around the glass fiber G1 that has been drawn and forcibly cooled.

The resin coating device 12 includes therein a first die 12A arranged on the upstream side and a second die 12B arranged on the downstream side in the running direction of the glass fiber G1. The first die 12A applies a primary resin around the glass fiber G1. The second die 12B applies a secondary resin around the primary resin applied around the glass fiber G1. As the primary resin for the inner layer (for the primary coating layer), an ultraviolet curable resin that becomes relatively soft after curing is used. As the secondary resin for the outer layer (for the secondary coating layer), an ultraviolet curable resin that becomes relatively hard after curing is used. Depending on the type of optical fiber, the coating resin layer may be one layer. A thermosetting resin may also be used as the coating resin.

The resin supply device 13 is configured to supply the primary resin P to the first die 12A through the pipe 20A and supply the secondary resin S to the second die 12B through the pipe 20B. The pipes 20A and 20B are provided with pipe heating devices 21A and 21B, respectively, and the temperature in the pipe 20A of the primary resin P flowing into the first die 12A and the temperature of the secondary resin S flowing into the second die 12B are controlled. The temperature inside 20B can be controlled to a desired temperature. The resin supply device 13 includes a first supply section 13A for supplying the primary resin P to the first die 12A and a second supply section 13B for supplying the secondary resin S to the second die 12B. When supplying the resin from the first supply unit 13A and the second supply unit 13B, the resin supply device 13 applies pressure to the primary resin P and the secondary resin S, respectively, and supplies them to the resin coating device 12 .

The resin curing device 14 is provided downstream of the resin coating device 12 in the running direction of the glass fiber G1. The resin curing device 14 is configured to cure the primary resin P and the secondary resin S applied to the glass fiber G1 by the resin coating device 12 . The resin curing device 14 is, for example, an ultraviolet irradiation device, and cures the resin by irradiating ultraviolet rays. The optical fiber G2 formed by curing the resin is wound around the winding drum 17 via the guide roller 15 and the take-up section 16 .

The drawing control device 18 controls the drawing conditions (heating temperature of the heater, feeding speed of the optical fiber preform G, take-up take-up speed of unit 16, etc.). Specifically, the drawing control device 18 controls the drawing conditions so that the drawing speed is kept constant when the drawing speed increases after the drawing and reaches the drawing speed of the steady drawing. The drawing control device 18 also outputs drawing speed information to the temperature control device 19 .

The temperature control device 19 is configured to control the temperatures of the first die 12A and the second die 12B to predetermined temperatures. Specifically, the temperature control device 19 causes a fluid to flow inside the resin coating device 12 and around the first die 12A and the second die 12B through, for example, pipes 19A and 19B, thereby The temperature of the second die 12B is controlled. By controlling the temperatures of the first die 12A and the second die 12B, the temperature of the primary resin P in the first die 12A and the temperature of the secondary resin S in the second die 12B are controlled.

The temperature control device 19 acquires the drawing speed information from the drawing control device 18 and controls the temperatures of the first die 12A and the second die 12B to predetermined temperatures according to the drawing speed. Specifically, while the drawing speed is low, the temperature control device 19 lowers the temperature of the first die 12A and the second die 12B below the temperatures of the first die 12A and the second die 12B during steady-state drawing. While the speed is increasing, the temperatures of the first die 12A and the second die 12B are raised to the set temperatures of the first die 12A and the second die 12B during steady wire drawing.

The temperature control device 19 is configured to control the temperature of the primary resin P supplied into the first die 12A and the temperature of the secondary resin S supplied into the second die 12B to predetermined temperatures. may Specifically, the temperature control device 19 may control the temperature of the primary resin P in the first supply section 13A of the resin supply device 13 and the temperature of the secondary resin S in the second supply section 13B. By adjusting the temperature of the primary resin P within the first supply section 13A and the temperature of the secondary resin S within the second supply section 13B, the temperature of the primary resin P supplied into the first die 12A and the temperature of the second die 12B are adjusted. The temperature of the secondary resin S supplied inside is controlled. Alternatively, the temperature control device 19 acquires the drawing speed information from the drawing control device 18, and according to the drawing speed, the pipe provided in the pipe 20A connecting the first supply section 13A and the first die 12A By adjusting the temperature of the heating device 21A and the temperature of the pipe heating device 21B provided in the pipe 20B connecting the second supply part 13B and the second die 12B, respectively, the temperatures of the primary resin P and the secondary resin S may be controlled.

Also in this case, the temperature control device 19 acquires the linear speed information from the drawing control device 18, and according to the linear speed, the resin supply device 13 (the first supply section 13A and the second supply section 13B) and the pipes 20A and 20B can be controlled to a predetermined temperature. Specifically, while the linear velocity is low, the resin temperature in the resin supply device 13 and the pipes 20A and 20B is made lower than the resin temperature in the resin supply device 13 and the pipes 20A and 20B during steady wire drawing. During the rise, the resin temperature may be raised to the resin temperature at the time of steady drawing.

Next, a method for manufacturing an optical fiber using the optical fiber manufacturing apparatus 1 will be described.
First, the lower end portion of the optical fiber preform G is heated in the drawing furnace 10, and a part (glass lump) is dropped by its own weight. . Furthermore, when the diameter of the rod-shaped glass that hangs down is reduced to become fibrous glass, it is passed through the forced cooling device 11, the resin coating device 12, and the resin curing device 14, and passed through the guide rollers 15 and the take-up unit 16. It is hooked and guided to the winding drum 17 (leading process). Then, after winding the end of the glass around the winding drum 17, drawing is performed while gradually increasing the drawing speed to form the glass fiber G1 (drawing speed increasing step). When the drawing speed reaches the drawing speed for steady drawing, the increase in drawing speed is terminated, and drawing is performed while the drawing speed is maintained (steady drawing speed) (steady drawing step). An optical fiber formed by stationary drawing is used as a product (product picking). For example, the drawing speed during steady drawing is 2000 m/min or more. The glass fiber G1 formed by drawing passes through the forced cooling device 11 and is cooled to a predetermined temperature, then passes through the resin coating device 12, and is coated with two layers of resin (primary resin P and secondary resin P) on its outer periphery. Resin S) is applied all at once.

FIG. 2 is a diagram showing the relationship between the linear velocity and the temperatures of the first die 12A and the second die 12B. FIG. 3 is a diagram showing the relationship between the line speed, the temperature of the primary resin P supplied to the first die 12A, and the temperature of the secondary resin S supplied to the second die 12B. 2 and 3, the vertical axis indicates temperature (° C.) or linear velocity (m/min), and the horizontal axis indicates elapsed time from the start of production.

As shown in FIG. 2, in the steady drawing process, the drawing speed is controlled to be the drawing speed V1, and the temperatures of the first die 12A and the second die 12B are controlled to be the temperature T1. The temperature control device 19 sets the temperature of the first die 12A and the second die 12B (temperature T2 in FIG. 2) at the time of steady drawing at the start of increasing the drawing speed in the drawing speed increasing step from lead drawing to steady drawing. The temperatures of the first die 12A and the second die 12B are controlled so as to be lower than the temperature T1 of . Further, the temperature control device 19 controls the temperatures of the first die 12A and the second die 12B so that the temperatures of the first die 12A and the second die 12B rise to the temperature T1 during the increase of the linear speed. That is, when the linear velocity reaches a predetermined linear velocity (linear velocity V2 in FIG. 2), the temperature control device 19 starts increasing the temperature of the first die 12A and the second die 12B, and the temperature rises to the temperature T1. increase until For example, the difference between the temperature T1 in the steady drawing step and the temperature T2 in the drawing speed increasing step is 5°C or higher and 40°C or lower, preferably 5°C or higher and 30°C or lower. The relationship between the linear velocity V1 in the steady drawing process and the linear velocity V2 in the increasing linear velocity process is V2<V1, preferably V2<V1×0.9, more preferably V2<V1×0.8. be.
The temperature rise of the first die 12A and the second die 12B from the temperature T2 to the temperature T1 may be raised once or may be raised in multiple steps. In particular, when the difference between the temperature T2 and the temperature T1 is large, it is preferable to increase the temperature in multiple steps.
In the above example, both the first die 12A and the second die 12B are subjected to temperature control as shown in FIG. 2, but the present invention is not limited to this example. For example, for only one of the first die 12A and the second die 12B, in the step of increasing the linear speed from lead drawing to steady drawing, the temperature (temperature T2 in FIG. 2) at the start of the linear speed increase is is lower than the temperature T1 during steady drawing, and the temperature may be controlled so that the temperature rises to the temperature T1 in the course of increasing the drawing speed.

Further, as shown in FIG. 3, in the steady drawing process, the temperature of the primary resin P supplied to the first die 12A is controlled to be the temperature T3, and the temperature of the secondary resin S supplied to the second die 12B is controlled. The temperature is controlled to be temperature T4. The temperature control device 19 controls the temperature of the primary resin P supplied to the first die 12A, that is, the first The temperature of the primary resin P is controlled so that the temperature of at least one of the supply section 13A and the pipe 20A (temperature T5 in FIG. 3) is lower than the temperature T3 during steady wire drawing. Furthermore, the temperature control device 19 controls the temperature of the secondary resin S supplied to the second die 12B at the start of increasing the linear velocity, that is, the temperature of at least one of the second supply section 13B of the resin supply device 13 and the pipe 20B ( The temperature of the secondary resin S is controlled so that the temperature T6) in FIG. 3 is lower than the temperature T4 during steady wire drawing. Further, when the linear velocity reaches a predetermined linear velocity (linear velocity V3 in FIG. 3) in the middle of increasing the linear velocity, the temperature control device 19 increases the temperature of the primary resin P supplied to the first die 12A. The temperature of the primary resin P is controlled so that it rises to T3. Similarly, the temperature control device 19 controls the temperature of the secondary resin S supplied to the second die 12B when the linear velocity reaches a predetermined linear velocity (linear velocity V3 in FIG. 3) in the middle of increasing the linear velocity. The temperature of the secondary resin S is controlled so that it rises to the temperature T4. That is, when the linear velocity reaches a predetermined linear velocity (linear velocity V3 in FIG. 3), the temperature control device 19 starts increasing the temperatures of the primary resin P and the secondary resin S to temperatures T3 and T4. up to For example, the difference between the temperature T3 and the temperature T5 of the primary resin P is 5°C or higher and 30°C or lower, preferably 5°C or higher and 20°C or lower. The difference between the temperature T4 and the temperature T6 of the secondary resin S is 5°C or higher and 30°C or lower, preferably 5°C or higher and 20°C or lower. Since the resin materials used for the primary resin P and the secondary resin S are different, the predetermined temperature during steady wire drawing is different between the temperature T3 and the temperature T4. Further, the predetermined linear velocity (linear velocity V3 in FIG. 3) may be different between the primary resin P and the secondary resin S.
In the above example, both the primary resin P supplied to the first die 12A and the secondary resin S supplied to the second die 12B are subjected to temperature control as shown in FIG. is not limited to For example, the temperature control shown in FIG. 3 may be applied to only one of the primary resin P supplied to the first die 12A and the secondary resin S supplied to the second die 12B. That is, for only the primary resin P supplied to the first die 12A, the primary resin P supplied to the first die 12A at the start of increasing the linear speed in the linear speed increasing process from lead drawing to steady wire drawing , that is, the temperature of at least one of the first supply portion 13A of the resin supply device 13 and the pipe 20A (temperature T5 in FIG. 3) is lower than the temperature T3 during steady wire drawing. , and when the linear speed reaches a predetermined linear speed (linear speed V3 in FIG. 3) during the linear speed increase, the temperature of the primary resin P supplied to the first die 12A rises to temperature T3. The temperature of the primary resin P may be controlled so as to control the temperature. Alternatively, for only the secondary resin S supplied to the second die 12B, the secondary resin S supplied to the second die 12B will be , that is, the temperature of at least one of the second supply portion 13B of the resin supply device 13 and the pipe 20B (temperature T6 in FIG. 3) is lower than the temperature T4 during steady wire drawing. and when the linear velocity reaches a predetermined linear velocity (linear velocity V3 in FIG. 3) in the middle of increasing the linear velocity, the temperature of the secondary resin S supplied to the second die 12B rises to the temperature T4. The temperature of the secondary resin S may be controlled so that the temperature of the secondary resin S increases.

Thus, by making the temperature T2 of the first die 12A and the second die 12B in the drawing speed increasing process lower than the temperature T1 of the first die 12A and the second die 12B in the steady drawing process, The viscosity of the primary resin P and the secondary resin S when applied around the glass fiber G1 in the resin applicator 12 is determined by the primary resin P applied around the glass fiber G1 in the resin applicator 12 in the steady drawing process. and the viscosity of the secondary resin S becomes higher. Similarly, the temperature T5 of the primary resin P and the temperature T6 of the secondary resin S supplied into the resin coating device 12 in the linear speed increasing process are set to the primary resin P supplied into the resin coating device 12 in the steady drawing process. and the temperature T4 of the secondary resin S, the viscosities of the primary resin P and the secondary resin S when applied around the glass fiber G1 in the step of increasing the drawing speed will be lower than the temperature T3 of the glass fiber S in the steady drawing step. It becomes higher than the viscosity of the primary resin P and the secondary resin S applied around G1. The viscosities of the primary resin P and the secondary resin S when applied around the glass fiber G1 in the linear velocity increasing step are preferably, for example, 1 Pa·s or more. The viscosities of the primary resin P and the secondary resin S in the linear velocity increasing step are more preferably 1.5 Pa·s or more.

The glass fiber G1 coated with resin passes through a resin curing device 14, where the resin is cured to become an optical fiber G2. The optical fiber G2 is wound around the winding drum 17 via the guide roller 15 and the take-up section 16 . FIG. 4 is a cross-sectional view of an optical fiber 100 manufactured by the optical fiber manufacturing apparatus 1. FIG. The optical fiber 100 has a first coating resin layer 102 and a second coating resin layer 103 made of a primary resin P and a secondary resin S formed concentrically on the outer periphery of a glass fiber 101 composed of a core layer and a clad layer. The optical fiber 100 is formed, for example, so that the diameter D1 of the glass fiber 101 is 124 μm or more and 126 μm or less, and the diameter D2 of the second coating resin layer 103 is 235 μm or more and 255 μm or less.

In this embodiment, in the step of increasing the linear velocity, the flow rate of the cooling gas introduced into the forced cooling device 11 is controlled so that the temperature of the glass fiber G1 when entering the resin coating device 12 is kept within a predetermined range. Control to temperature. The temperature of the glass fiber G1 in the drawing speed increasing process is preferably higher than the temperature of the glass fiber G1 in the steady drawing process. Specifically, the temperature of the glass fiber G1 when entering the resin coating device 12 is controlled to be 60° C. or higher and 85° C. or lower in the linear velocity increasing process. More preferably, the temperature of the glass fiber G1 is 70° C. or higher and 85° C. or lower, and still more preferably 75° C. or higher and 80° C. or lower. Note that if the temperature of the glass fiber G1 becomes too high in the step of increasing the linear velocity, the application of the primary resin P and the secondary resin S to the glass fiber G1 becomes unstable, and the resin is not pulled appropriately, resulting in disconnection of the optical fiber G2. more likely to connect. Therefore, it is preferable to set the temperature of the glass fiber G1 in the drawing speed increasing process within a range of, for example, 80° C. or less.

(Example)
Evaluation results of each example in the above optical fiber manufacturing method will be described below with reference to FIG.
FIG. 5(a) is a diagram showing temperature control of the resin coating device 12 (the first die 12A and the second die 12B) in Examples 1-4. In (a) of FIG. 5, the vertical axis indicates temperature (° C.), and the horizontal axis indicates elapsed time from the start of production.

In the examples shown in (a) to (d) of FIG. 5, the drawing speed control of the optical fiber was set to be the same as the drawing speed control shown in FIG. As shown in FIG. 5(a), in Example 1, the temperature of the resin coating device 12 was kept constant from when the linear speed was increased to when the drawing was steady. On the other hand, in Example 2, the temperature of the resin coating device 12 is set to a temperature lower than the set temperature for steady wire drawing (about the same temperature as in Example 1) when the linear speed increase is started, and the linear speed is increased. When reaching a predetermined point in time, the temperature of the resin coating device 12 was started to rise until the temperature reached the set temperature for steady wire drawing. In Examples 3 and 4, as in Example 2, the temperature of the resin coating device 12 is set to a temperature lower than the set temperature for steady wire drawing when starting to increase the linear speed, and at a predetermined point during the linear speed increase, When the temperature reached, the temperature of the resin coating device 12 was started to rise until the temperature reached the set temperature for steady wire drawing. In Examples 3 and 4, the timing of raising the temperature of the resin coating device 12 was later than in Example 2. Furthermore, in Example 4, the temperature of the glass fiber G2 controlled by being cooled by the forced cooling device 11 was set higher than in Examples 1-3.

FIG. 5(b) is a diagram showing changes in the outer diameter of the optical fiber G2 when temperature control of the resin coating device 12 is executed as in Examples 1-4. In (b) of FIG. 5, the vertical axis indicates the coating diameter (μm) of the optical fiber G2, and the horizontal axis indicates the elapsed time from the start of manufacturing. The coating diameter (μm) of the optical fiber G2 is, as shown in FIG. is the outer diameter of the optical fiber G2 (100) in a state of being formed into a shape.
As shown in (b) of FIG. 5 , immediately after the start of increasing the linear velocity, the linear velocity of the optical fiber G2 is low, so the primary resin P and the secondary resin are pulled by the glass fiber G1 passing through the resin coating device 12. Since the amount of S increases, the coating diameter of the optical fiber G2 also increases. After that, as the drawing speed increases, the amounts of the primary resin P and the secondary resin S pulled by the glass fiber G1 gradually decrease, and the coating diameter of the optical fiber G2 gradually decreases. At the time of steady drawing (at a constant drawing speed), the amount of the primary resin P and the secondary resin S pulled by the glass fiber G1 is stabilized at a predetermined amount, and all of Examples 1 to 4 coat the optical fiber G2. The diameter becomes a constant value. When the temperature control of the resin coating device 12 is changed in Examples 1 to 4 as shown in (a) of FIG. It was confirmed that the coated diameter of the optical fiber G2 became thinner in the step of increasing the drawing speed because the temperature of the G2 was low. Furthermore, in Examples 3 and 4, in which the temperature rise of the resin coating device 12 is started later than in Example 2, the coating diameter of the optical fiber G2 is increased more than in Example 2 throughout the line speed increasing process. was also found to be thinner. In Example 4, when compared with Example 3, the coating diameter is maintained smaller than during steady drawing.

FIG. 5(c) is a diagram showing the amount of primary resin used in Examples 1-4, and FIG. 5(d) is a diagram showing the amount of secondary resin used in Examples 1-4. In (c) and (d) of FIG. 5, the vertical axis indicates the usage amount (kg) of the primary resin P and the secondary resin S, respectively, and the horizontal axis indicates the elapsed time from the start of production.
As shown in (c) of FIG. 5, although there was no significant difference in the amount of primary resin P used in Examples 1, 2, and 3, Example 4 used less primary resin P than Example 1. It was confirmed that the amount was significantly reduced. Further, as shown in (d) of FIG. 5, it was confirmed that the usage amount of the secondary resin S was significantly reduced in Examples 2 to 4 compared to Example 1. That is, the temperature of the resin coating device 12 is set to a temperature lower than the set temperature for steady wire drawing in the linear speed increasing step, and the temperature of the primary resin P and the secondary resin S in the linear speed increasing step is set to the temperature of the primary resin P in the steady wire drawing step. and the temperature of the secondary resin S, it has been confirmed that there is an effect of reducing the amount of resin used. In particular, in Example 4, in which the temperatures of the primary resin P and the secondary resin S are controlled while also controlling the temperature of the glass fiber G1, the total usage of the primary resin P and the secondary resin S is the same as that of the primary resin P and the secondary resin S in Example 1. It was confirmed that the amount of the secondary resin S was reduced by about 25% compared to the total amount used.

As described above, according to the optical fiber manufacturing method of the present embodiment, the temperature of the resin coating device 12 is set to a temperature lower than the set temperature for steady drawing in the drawing speed increasing step. The temperatures of the primary resin P and the secondary resin S are made lower than the temperatures of the primary resin P and the secondary resin S in the steady drawing process. As a result, the viscosities of the primary resin P and the secondary resin S in the linear speed increasing process become higher than the viscosities of the primary resin P and the secondary resin S in the steady drawing process. By increasing the viscosities of the primary resin P and the secondary resin S in this way, the amount of pulling of the primary resin P and the secondary resin S by the glass fiber G1 when the linear velocity is increased is reduced, and when the linear velocity is increased, the circumference of the glass fiber G1 is reduced. less primary resin P and secondary resin S are applied to the In other words, the coating diameter of the optical fiber G2 is reduced during the linear velocity increasing step. As a result, the amounts of the primary resin P and the secondary resin S used during the linear velocity increase, which is a step that is discarded without becoming a product, can be reduced.
In the final steady-state drawing process, in addition to the coating diameter of the optical fiber G2, the first coating resin layer 102 and the second coating resin layer 103 composed of the primary resin P and the secondary resin S are applied to the glass fiber G1 (101). Concentricity (non-uniform thickness ratio) also needs to satisfy the desired standard. Therefore, in order to reduce the amount of resin used, the viscosity of the resin is controlled at a drawing speed lower than the drawing speed in the steady drawing step (drawing speed increasing step).

In addition, the temperature of the primary resin P and the secondary resin S supplied into the resin coating device 12 in the linear speed increasing process is higher than the temperature of the primary resin P and the secondary resin S supplied into the resin coating device 12 in the steady wire drawing process. should also be low. This method also makes it possible to make the viscosities of the primary resin P and the secondary resin S during an increase in drawing speed higher than the viscosities of these resins at a drawing speed at the time of steady drawing. and the amount of secondary resin S used can be reduced.

Further, it is more preferable that the temperature of the glass fiber G1 entering the resin coating device 12 in the drawing speed increasing process is higher than the temperature of the glass fiber G1 entering the resin coating device 12 in the steady drawing process. According to this method, the pulling amount of the primary resin P and the secondary resin S by the glass fiber G1 whose drawing speed is increasing can be further reduced, and a further reduction in the amount of resin used can be expected.

Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the disclosure. Also, the number, positions, shapes, etc. of the constituent members described above are not limited to those in the above embodiment, and can be changed to suitable numbers, positions, shapes, etc. in carrying out the present disclosure.

In the above embodiment, the amount of resin used in the linear speed increasing process is reduced by varying the temperature of the resin in the resin coating device between the linear speed increasing process and the steady wire drawing process, but the present invention is not limited to this example. For example, while the temperature of the resin is kept constant, the temperature of the glass fiber G1 entering the resin coating device 12 is increased in the step of increasing the linear velocity, thereby reducing the amount of pulling of the resin by the glass fiber G1 during the increase of the linear velocity. You can do it. That is, by adjusting the flow rate of the cooling gas introduced into the forced cooling device 11, the cooling temperature of the glass fiber G1 in the step of increasing the linear velocity is kept above a certain temperature. As a result, only the viscosity of the resin surrounding the vicinity of the glass fiber G1 in the first die 12A and the second die 12B decreases, so the amount of resin pulled by the glass fiber G1 is reduced. As a result, the coated diameter of the optical fiber G2 becomes thin in the step of increasing the drawing speed, and the amount of resin used can be reduced.

Further, the optical fiber manufacturing apparatus 1 described above is a dual coating type manufacturing apparatus, but is not limited to this. The optical fiber manufacturing apparatus 1 may be a tandem coating type manufacturing apparatus that applies and cures resin layer by layer. In the tandem coating type manufacturing apparatus, the first die 12A and the second die 12B are arranged separately. In the case of the tandem coating method, the resin curing device 14 includes a first curing section arranged downstream of the first die 12A and upstream of the second die 12B, and a second curing section arranged downstream of the second die 12B. consists of The first curing section cures the primary resin applied by the first die 12A. The second curing section cures the secondary resin applied by the second die 12B. Even in this case, while the drawing speed is low, the temperature of the primary resin P in the first die 12A and the temperature of the secondary resin S in the second die 12B are lowered from those during steady drawing, and the primary resin P and the secondary resin S By increasing the viscosity of , the same effect as the above embodiment can be obtained.

In the above embodiment, the temperature control device 19 controls the resin temperature in the first die 12A and the second die 12B by causing the fluid to flow inside the resin coating device 12, but the present invention is not limited to this. For example, the temperature control device 19 may control the resin temperature by providing a heating device and a cooling device in the resin coating device 12 and controlling the operation of the heating device and the cooling device.

In the above embodiment, the temperature control device 19 obtains the drawing speed information from the drawing control device 18, but the present invention is not limited to this. For example, a measuring instrument for measuring the linear velocity of the optical fiber G2 may be arranged and linear velocity information may be obtained from the measuring instrument.

1: Optical fiber manufacturing device 10: Drawing furnace 11: Forced cooling device 12: Resin coating device 12A: First die 12B: Second die 13: Resin supply device 13A: First supply section 13B: Second supply section 14 : Resin curing device 15: Guide roller 16: Take-up unit 17: Winding drum 18: Drawing control device 19: Temperature control device 19A, 19B, 20A, 20B: Pipe 21A, 21B: Pipe heating device 100: Optical fiber 101 : Glass fiber 102: First coating resin layer 103: Second coating resin layer G: Optical fiber base material G1: Glass fiber G2: Optical fiber P: Primary resin S: Secondary resin T1 to T6: Temperature V1 to V3: Optical fiber line speed of

Claims (6)

A glass fiber formed by drawing an optical fiber preform while heating and melting it is introduced into a resin coating device filled with a resin, and after the resin is coated around the glass fiber, the glass fiber is coated. An optical fiber manufacturing method for manufacturing an optical fiber in which a coating resin layer is formed around the glass fiber by curing the resin by applying a curing treatment to the resin applied around the glass fiber,
a step of providing a lead for taking over the optical fiber with a take-up device;
a drawing speed increasing step of performing drawing while increasing the drawing speed up to the drawing speed at the time of the steady drawing after the drawing and before the steady drawing;
a steady drawing step of performing the steady drawing of product picking;
including
The method of manufacturing an optical fiber, wherein the viscosity of the resin in the resin coating device in the step of increasing the drawing speed is higher than the viscosity of the resin in the resin coating device in the steady drawing step. 2. The light according to claim 1, wherein the temperature of the resin supplied into the resin coating device in the linear speed increasing step is lower than the temperature of the resin supplied into the resin coating device in the steady drawing step. Fiber manufacturing method. 3. The method of manufacturing an optical fiber according to claim 1, wherein the temperature of said resin coating device in said drawing speed increasing step is lower than the temperature of said resin coating device in said steady drawing step. 4. The temperature of the glass fiber entering the resin coating device in the step of increasing the drawing speed is higher than the temperature of the glass fiber entering the resin coating device in the steady drawing step. The method for manufacturing an optical fiber according to any one of Claims 1 to 3. The method for manufacturing an optical fiber according to any one of claims 1 to 4, wherein the viscosity of the resin in the resin coating device in the linear velocity increasing step is 1 Pa·s or more. A glass fiber formed by drawing an optical fiber preform while heating and melting it is introduced into a resin coating device filled with a resin, and after the resin is coated around the glass fiber, the glass fiber is coated. An optical fiber manufacturing method for manufacturing an optical fiber in which a coating resin layer is formed around the glass fiber by curing the resin by applying a curing treatment to the resin applied around the glass fiber,
a step of providing a lead for taking over the optical fiber with a take-up device;
a drawing speed increasing step of performing drawing while increasing the drawing speed up to the drawing speed at the time of the steady drawing after the drawing and before the steady drawing;
a steady drawing step of performing the steady drawing of product picking;
including
A method for manufacturing an optical fiber, wherein the temperature of the glass fiber entering the resin coating device in the drawing speed increasing step is higher than the temperature of the glass fiber entering the resin coating device in the steady drawing step.

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