JP5210575B2 - Plastic optical fiber manufacturing equipment - Google Patents

Description

  The present invention relates to an apparatus for manufacturing a plastic optical fiber capable of reducing fluctuations in the outer diameter when melt spinning the plastic optical fiber.

  Conventionally, spinning production of a plastic optical fiber has been performed by a production apparatus 110 as shown in FIG. The manufacturing apparatus 110 includes a spinneret 120 in which one or more discharge ports for continuously discharging a molten resin are arranged in a circumferential shape, a staggered shape, or a straight line, and a heat insulating material provided immediately below the spinneret 120. It comprises a cylinder 130 and a cooling device 140 for cooling the melt-spun plastic optical fiber. For example, the plastic optical fiber Z melt-spun from the spinneret 120 is cooled by the cooling air blown from the cooling device 140 after passing through the inside of the heat insulating tube 130, and then drawn by the nip roll 170 through the guide 150 and drawn. Sent to the process.

  In the production of such a plastic optical fiber, the uniformity of the outer diameter in the spinning process greatly affects the uniformity of the outer diameter of the obtained plastic optical fiber. When a plastic optical fiber having a non-uniform outer diameter is spun in the spinning process and sent to the drawing process, a large tensile tension is concentrated on a portion with a thin outer diameter, and the portion becomes even thinner. Uniformity increases. Therefore, in order to make the outer diameter of the obtained plastic optical fiber uniform, it is very important to control the outer diameter fluctuation in the spinning process.

  The outer diameter fluctuation of the plastic optical fiber that occurs in the spinning process includes an outer diameter fluctuation that is regular and periodic, and an outer diameter fluctuation that is irregular and not periodic. One of the factors causing regular and periodic fluctuations in the outer diameter is considered to be the effect of fluctuations in the discharge amount of the metering pump. As a method of controlling the outer diameter fluctuation, for example, a method of making the primary resin pressure of a metering gear pump constant is shown (Patent Document 1). In addition, using a plurality of gear-type metering pumps, the molten resin is distributed to a plurality of raw material streams having different phases of the discharge amount fluctuation period, and the phase of the fluctuation period of the discharge amount is canceled out for these plural raw material streams. A method for controlling fluctuations in the discharge amount by combining them together is disclosed (Patent Document 2). However, with these techniques, it is difficult to control irregular and non-periodic outer diameter fluctuations even though regular and periodic outer diameter fluctuations can be controlled.

  As a method for controlling irregular and non-periodic outer diameter fluctuations, a method of changing the wind direction of the upper part of the cooling air to an obliquely upward direction in a cooling device that blows out cooling air is disclosed (Patent Document 3). However, the technique of Patent Document 3 has a problem in that a difference in outer diameter variation occurs between the plastic optical fibers depending on the distance between the cooling air blowing port and the passing plastic optical fiber. Further, when manufacturing different types of plastic optical fibers, complicated fine adjustment of the wind speed is required each time.

Patent Document 4 is provided with a shield plate that prevents cooling air from entering the heat retaining cylinder and a multi-stage structure type cooling device that can individually set the wind speed and temperature, and blows wind at a gradually lower temperature from the upper part. A method for controlling fluctuations in the outer diameter of the obtained plastic optical fiber by cooling the melt-spun plastic optical fiber is shown. The technique of Patent Document 4 can control the outer diameter fluctuation of the plastic optical fiber to be small without complicated fine adjustment of the wind speed depending on the product type.
JP-A-2-24923 JP-A-5-11127 JP-A-4-225303 JP 2005-42247 A

However, the direction of the cooling air blown out from the cooling device may be disturbed by the warm air generated in the heat insulating cylinder, and the outer diameter fluctuation may not be fully controlled. Therefore, a plastic optical fiber manufacturing apparatus that can more stably control the outer diameter variation of the obtained plastic optical fiber is desired.
Accordingly, an object of the present invention is to provide a plastic optical fiber manufacturing apparatus capable of controlling fluctuations in the outer diameter with high stability without reducing the productivity by maintaining the spinning speed.

  In the present invention, a heat insulating cylinder is provided adjacent to a spinneret having one or more discharge ports for discharging molten resin in a strand shape, and a cooling device is provided close to the side of the heat insulating cylinder opposite to the spinneret side. The cooling device has a multi-cylinder assembly for rectifying the wind blown to the molten resin, and the opening area of each cylindrical body forming the multi-cylinder assembly A plastic optical fiber manufacturing apparatus in which S and length L are L / S = 0.5 to 15 is provided.

  According to the plastic optical fiber manufacturing apparatus of the present invention, it is possible to manufacture with high stability a plastic optical fiber in which fluctuations in the outer diameter are suppressed while maintaining high productivity.

Hereinafter, an embodiment of a plastic optical fiber manufacturing apparatus according to the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, the plastic optical fiber manufacturing apparatus 10 of the present invention includes a spinneret 20, a heat retaining cylinder 30, a cooling device 40, a guide 50, an outer diameter measuring device 60, and a nip roll 70.

  The spinneret 20 is provided with, for example, one or more discharge ports arranged in a circumferential shape, a staggered shape, or a straight line shape. In addition, a heat retaining cylinder 30 is provided immediately below the spinneret 20. An opening 32 for allowing a melt-spun plastic optical fiber to pass through is provided below the heat retaining cylinder 30. A cooling device 40 for cooling the melt-spun plastic optical fiber is provided under the heat retaining cylinder 30.

As shown in FIG. 1, the cooling device according to the present embodiment has a three-stage structure in which the cooling devices 40 are stacked in three stages, and the wind speed and temperature can be individually set (hereinafter, each cooling device 40 in three stages is These are the upper cooling device 40a, the middle cooling device 40b, and the lower cooling device 40c in order from the upper stage). A cooling device may be used independently and may be used by stacking two or more as mentioned above.
When cooling a melt-spun plastic optical fiber using a plurality of cooling devices 40, the temperature of the cooling air from the cooling device below is lower than the temperature of the cooling air from the cooling device on the upper side. Should be set to be low. For example, in FIG. 1, the temperature of the cooling air is preferably lower in the middle cooling device 40b than in the upper cooling device 40a and in the lower cooling device 40c than in the middle cooling device 40b. Further, the cooling air from the middle cooling device 40b and the lower cooling device 40c may be the same temperature as long as it is lower than the temperature of the cooling air from the upper cooling device. By doing in this way, the outer diameter fluctuation | variation of a plastic optical fiber becomes easy to control.
As shown in FIG. 2, the cooling device 40 includes components such as a blower 41, a resistor 42, a cold / hot water coil 43, and a multi-tubular assembly 45. If it can blow out, the kind of parts, the quantity, and arrangement | positioning will not be specifically limited.
First, the wind blown by the blower 41 is diffused by the resistor 42 and then sent to the cold / hot water coil 43. Circulating water is supplied to the cold / hot water coil 43 from an external cold / hot water circulation device 44, and the temperature of the cooling air is adjusted by feedback control of the temperature of the circulating water. The wind that has passed through the cold / hot water coil 43 is once accumulated in the accumulation portion d and is made uniform, and then blown out from each cylindrical body 46 of the multi-cylinder assembly 45.

The plastic optical fiber manufacturing apparatus 10 according to the present invention is characterized in that the cooling device 40 has a multi-cylinder assembly 45. In the conventional plastic optical fiber manufacturing apparatus, the entire cooling air blown from the cooling device is rectified in a lump with a wire mesh or the like, so that a high rectifying effect has not been obtained. For this reason, the cooling air may be disturbed by the warm air blown out from the inside of the heat insulating cylinder 30, and the outer diameter fluctuation of the obtained plastic optical fiber may not be fully controlled. However, in the manufacturing apparatus 10 of the present invention, the multi-cylinder assembly 45 is used to rectify the cooling air blown from the cooling device 40 by the respective cylindrical bodies 46. In this way, the cooling air can be divided and rectified separately by each cylindrical body 46, and if the length of the cylindrical body is further increased, the rectifying effect can be greatly increased. Therefore, the cooling air blown out from the cooling device 40 goes straight without being disturbed by the hot air blown out from the heat retaining cylinder 30 and so on, so that the outer diameter fluctuation of the plastic optical fiber can be controlled as desired.
In the plastic optical fiber manufacturing apparatus 10 of the present invention, each cylindrical body 46 forming the multi-cylinder assembly 45 has an opening area S and a length L of the cylindrical body 46 such that L / S = 0.5. To be ~ 15. The relationship between the opening area S and the length L of the cylindrical body 46 is preferably in the range of L / S = 1-12. If L / S is 15 or less, a large amount of energy is not required to blow cooling air from the cooling device, so that economic efficiency is improved. Moreover, if L / S is 0.5 or more, the cooling air blown out from the cooling device is sufficiently rectified, and the direction of the blown cooling air is stabilized.

  As the multi-tube aggregate 45 of the cooling device 40, for example, a honeycomb as shown in FIG. 3 can be used. In this case, an aluminum honeycomb is preferable, but not limited thereto. Further, it may be other than the honeycomb, for example, it may be an aggregate of cylindrical bodies such as a quadrilateral cross section, a pentagonal cross section, a circular cross section, etc., and some kinds of cylindrical bodies are mixed to form an aggregate. It may be a thing. Further, the L / S value of each cylindrical body may be different as long as it is in the range of 0.5 to 15.

  Further, as shown in FIG. 4, the cooling device 40 of the present invention has a chilled water coil 47 and an electric heater 49 to which chilled water is supplied from a chilled water circulation device 48 installed on the outside of the blower 41 on the multi-tube assembly 45 side. And the air cooled by the cold water coil 47 is heated by the electric heater 49 so as to obtain the cooling air having a set temperature. At this time, the cold water coil 47 may be closer to the multi-cylinder assembly 45 than the blower 41 or may be opposite to the multi-cylinder assembly 45 side.

  As shown in FIG. 1, the cooling device 40 (upper cooling device 40 a in the present embodiment) allows the uppermost cooling air from the cooling device 40 to pass immediately below the heat retaining cylinder 30. It is good to provide. Thus, by reducing the distance between the cooling device 40 and the heat retaining cylinder 30, it becomes easy to prevent convection from being generated by the warm air blown from the heat retaining cylinder 30.

  Further, the heat insulating cylinder 30 of the manufacturing apparatus 10 may be provided with a blocking plate 31 in order to stabilize the temperature and air flow inside the heat insulating cylinder 30. The blocking plate 31 is formed with an opening 32 through which the melt-spun plastic optical fiber passes (FIG. 1). The installation of the blocking plate 31 is effective when the wind speed of the cooling air is 0.4 m / sec or more. Further, if the blocking plate 31 is provided, the cooling air X blown out from the upper cooling device 40a does not enter the inside of the heat retaining cylinder 30 and disturb the airflow inside the heat retaining cylinder 30. Therefore, fluctuations in the outer diameter of the plastic optical fiber can be suppressed. Further, for example, as shown in FIG. 7, in the case where a blocking plate is not provided, the cooling air collides with the inner side surface 134 on the side far from the cooling device 140 of the heat insulating cylinder 130, and the rebounded cooling air is far from the cooling device. Therefore, there is a case where a difference occurs in the outer diameter fluctuation between the plastic optical fibers. As shown in FIG. 1, if the blocking plate 31 is provided, it is easy to prevent the cooling air from entering the heat insulating cylinder 30 and the cooling air can be prevented from colliding with the inner side surface 34 of the heat insulating cylinder 30. It is easy to reduce the outer diameter fluctuation difference between fibers.

  The blocking plate 31 preferably has a structure as shown in FIGS. The blocking plate 31 in FIG. 5A is provided to be inclined toward the inside of the heat insulating cylinder 30. On the other hand, the blocking plate in FIG. 5B is provided to be inclined toward the cooling device 40 side. Further, the shield plate 31 is provided with an opening 32 in the horizontally installed shield plate 31 as shown in FIG. 5C, and a side portion 33 c is formed on the inner side of the heat insulating cylinder at the peripheral portion of the opening 32. As shown in FIG. 5D, it is more preferable that the side portion 33d is formed on the peripheral portion of the opening portion 32 toward the cooling device side. Further, it is more preferable that the shield plate 31 provided as small as possible in the range where the opening diameter of the opening portion 32 formed in the shield plate 31 provided horizontally does not contact the plastic optical fiber. In addition, as shown in FIGS. 5C and 5D, the shielding plate 31 is horizontally provided, and the shielding plate 31 has one opening 32 for each plastic optical fiber. It is particularly preferred that it is provided.

  For example, when the cooling device 40 is used in three stages as in this embodiment, the temperature of the cooling air blown out from the upper cooling device 40a is preferably in the range of 20 to 70 ° C. By setting the temperature of the cooling air in this range, even when the wind speed of the cooling air is less than 0.4 m / sec, the fluid mass c by the cooling air from the upper cooling device 40a and the radiant heat from the spinneret 20 and It becomes easy to prevent thermal expansion of the fluid mass a caused by the temperature difference with the high temperature fluid mass b generated inside the heat retaining cylinder 30 due to heat radiation from the plastic optical fiber (FIG. 1). As a result, the natural convection caused by the fluid mass a being lighter than the fluid mass c and causing buoyancy is suppressed, and therefore, the natural convection is less likely to collide with the intermittent plastic optical fiber. It becomes easy to control the outer diameter variation of the plastic optical fiber. Further, if the temperature of the cooling air from the upper cooling device 40a is 20 ° C. or higher, the air density in the fluid mass a portion is reduced, so that the direction of the cooling air is easily maintained. Further, if the temperature of the cooling air from the upper cooling device 40a is 70 ° C. or less, the temperature difference between the cooling air from the middle cooling device 40b and the lower cooling device 40c can be reduced, and the outside diameter fluctuates due to the rising airflow generated thereby. It becomes easy to prevent that becomes large.

  Further, since the surface temperature of the plastic optical fiber is sufficiently lowered and then brought into contact with the guide 50 and the nip roll 70, the cooling air from the middle cooling device 40b and the lower cooling device 40c is at a lower temperature than the upper cooling device 40a. And it is preferable that it is 5-25 degreeC. Further, the temperature of the cooling air from the lower cooling device 40c is set to be equal to or lower than the temperature of the cooling air of the middle cooling device 40b. By setting it as such a temperature range, it becomes easy to prevent generation | occurrence | production of defects, such as a crack, when a plastic optical fiber contacts the guide 50 or the nip roll 70. FIG. Moreover, it is preferable that the wind speed of the cooling air from the intermediate | middle stage cooling device 40b and the lower stage cooling device 40c is 0.3-1.5 m / sec.

  The wind speed of the cooling air from the upper cooling device 40a should be 0.2 to 0.8 m / sec. If the temperature is 20 to 70 ° C., it is highly stable without adjusting the wind speed for each product type. The outer diameter fluctuation of most plastic optical fibers can be controlled. Here, it is preferable that the variation in the wind speed of the cooling air is within a range of ± 0.1 m / sec from the average flow velocity of each stage for each cooling air blown from the cooling device 40 of each stage. Further, the temperature spots are preferably within a range of ± 1 ° C. from the average temperature of each stage for each cooling air from the exceptional cooling device 40.

In the present embodiment, the cooling device 40 is described as being stacked in three stages, but a multi-stage structure type may be used. For example, the upper cooling device 40a may be further divided into multiple stages so that the temperature of the cooling air blown onto the plastic optical fiber is 20 to 70 ° C., and the temperature decreases from the upper stage toward the lower stage.
The length e of the heat insulating cylinder 30 and the height f of the upper cooling device 40a can be set as appropriate depending on the time until the plastic optical fiber Y is cooled and solidified and the spinning speed, but both are in the range of 50 to 500 mm. Is preferred.

EXAMPLES Hereinafter, an Example and a comparative example are shown and this invention is demonstrated in detail. In addition, this invention is not limited by the following description.
Evaluation methods in Examples and Comparative Examples are as shown below.
[Outer diameter fluctuation rate of plastic optical fiber]
The outer diameter of the plastic optical fiber after the spinning process was measured with a laser outer diameter measuring device (outer diameter measuring device 6 in FIG. 1) manufactured by Keyence Corporation at a sample interval of 0.1 sec and a sample time of 30 min. The standard deviation was determined from the measurement results. Next, the value of three times the standard deviation (3σ) was defined as the outer diameter fluctuation, and the outer diameter fluctuation rate was determined using this value. The outer diameter fluctuation rate is calculated by the equation (1).
A = (B / C) × 100 (1)
Here, A is the outer diameter fluctuation rate (%), B is the standard deviation three times (3σ), and C is the average outer diameter.

[Outer diameter fluctuation difference]
Outer diameter fluctuation of the plastic optical fiber of the farthest side in a cooling device and (A _1), the outer diameter fluctuation of the plastic optical fiber of the closest side (A ₂₎ outer diameter fluctuation difference with the A _T ( %).
A _T = | (A ₁ ) − (A ₂ ) |

[Example 1]
Polymethyl methacrylate (PMMA) was used as the core material, and vinylidene fluoride / tetrafluoroethylene (80/20 (mol%)) was used as the molten resin as the sheath material. The manufacturing apparatus has the apparatus configuration shown in FIGS. 1 and 2, the spinneret 20 has four outlets arranged circumferentially, and the length f of the heat retaining cylinder 30 is 300 mm. The length g of the cooling device 40a is 300 mm. As the multi-cylinder assembly 45 forming the cooling device 40, an aluminum honeycomb was used, the opening area S of each cylindrical body 46 was 10 mm ² , and the length L was 100 mm (L / S = 10). As shown in FIG. 6, the blocking plate 31 was provided with an opening 32 so that the distance g from the plastic optical fiber spun from the spinneret 20 was 12 mm and the opening diameter h was 100 mm. The take-up speed of the nip roll was 20 m / min, the spinning temperature was 230 ° C., the temperature of the cooling air from the upper cooling device 40a was 25 ° C., and the wind speed was 0.5 m / sec. The temperature of the cooling air from the middle cooling device 40b was 20 ° C., the wind speed was 0.5 m / sec, the temperature of the cooling air from the lower cooling device 40c was 20 ° C., and the wind speed was 0.5 m / sec. An attempt was made to manufacture a plastic optical fiber having a fiber outer diameter of 750 μm using the manufacturing apparatus 10.

[Example 2]
The plastic optical fiber is the same as in Example 1 except that the opening area S of each cylindrical body 46 forming the multi-cylinder assembly 45 is 20 mm ² and the length L is 100 mm (L / S = 5.0). Manufactured.

[Example 3]
The plastic optical fiber is the same as in Example 1 except that the opening area S of each cylindrical body 46 forming the multi-tubular assembly 45 is 70 mm ² and the length L is 100 mm (L / S = 1.4). Manufactured.

[Comparative Example 1]
The plastic optical fiber is the same as in Example 1 except that the opening area S of each cylindrical body 46 forming the multi-cylinder assembly 45 is 300 mm ² and the length L is 100 mm (L / S = 0.3). Manufactured.

[Comparative Example 2]
A plastic optical fiber is manufactured in the same manner as in Example 1 except that the opening area S of each cylindrical body 46 forming the multi-cylinder assembly 45 is 10 mm ² and the length L is 200 mm (L / S = 20). went.
Table 1 shows the conditions of each cylindrical body and the evaluation of the manufactured plastic optical fiber in Examples 1 to 3 and Comparative Examples 1 and 2.

In Examples 1 to 3, in which the opening area S and length L of each cylindrical body forming the multi-cylinder aggregate are appropriate conditions, the outer diameter variation rate of the manufactured plastic optical fiber is small, and the cooling device The difference in the outer diameter of the plastic optical fiber on the near side and the far side is small.
On the other hand, in Comparative Example 1 where the L / S is small, the manufactured plastic optical fiber has a large outer diameter fluctuation rate, and the plastic optical fiber on the side closer to the cooling device and the far side has a large difference in outer diameter fluctuation. Similarly, in Comparative Example 2 where the L / S is large, the manufactured plastic optical fiber has a large outer diameter variation rate, and the outer diameter variation difference between the plastic optical fiber near and far from the cooling device is also large.

  According to the plastic optical fiber manufacturing apparatus of the present invention, the outer diameter fluctuation of the manufactured plastic optical fiber can be suppressed with high stability, and the outer diameter fluctuation difference between the plastic optical fibers can be reduced. Thus, the manufacturing apparatus of the present invention is useful because a plastic optical fiber excellent in quality can be stably manufactured.

It is the schematic which shows an example of the manufacturing apparatus of the plastic optical fiber of this invention. It is the schematic which showed the cooling device 40 of the manufacturing apparatus 10 of FIG. 1 in detail. It is the front view which looked at the multicylinder aggregate | assembly 45 of the manufacturing apparatus 10 of this invention from the opening surface side. It is the schematic which showed in detail the other form of the cooling device 40 of the manufacturing apparatus of FIG. It is the schematic which shows the structure of the shielding board 30 of the manufacturing apparatus of FIG. It is the front view which looked at the shielding board used for the Example and the comparative example from the cooling device 40 side. It is the schematic which showed the manufacturing apparatus of the conventional plastic optical fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plastic optical fiber manufacturing apparatus 20 Spinneret 30 Heat insulation cylinder 40 Cooling apparatus 45 Multi-cylinder assembly 46 Cylindrical body

Claims (1)

A heat insulating cylinder is provided adjacent to a spinneret having one or more discharge ports for discharging the molten resin in a strand shape, and a cooling device is provided adjacent to the side of the heat insulating cylinder opposite to the spinneret side. Manufacturing equipment,
The cooling device has a multi-cylinder assembly for rectifying the wind blown to the molten resin, and an opening area S and a length L of each cylindrical body forming the multi-cylinder assembly are L / Plastic optical fiber manufacturing apparatus with S = 0.5-15.

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