JP2013204161A - Melt-spinning apparatus and manufacturing method of hollow fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt-spinning apparatus and a manufacturing method of a hollow fiber capable of easily determining suitability of a cooling environment in a region where molten resin is to be made to be fine.SOLUTION: A melt-spinning apparatus 1 solidifies molten resin spun from a nozzle 15 by applying fluid whose temperature is lower than that of molten resin. It includes measurement means 9 which measures a physical property value of the molten resin or a physical property value of the surroundings of the molten resin which changes according to the cooling state of the molten resin in the region where the molten resin is made to be fine in a cooling device 5.

Description

  The present invention relates to a melt spinning apparatus and a method for producing hollow fibers, and more particularly to a melt spinning apparatus used for producing a polyolefin porous hollow fiber membrane and a method for producing such hollow fibers.

  Conventionally, polyolefin porous hollow fiber membranes have been used in a wide range of fields such as wastewater treatment, production of ultrapure water, and air purification because they are excellent in chemical stability, strength characteristics, flexibility, etc. Yes. A method for producing such a polyolefin porous hollow fiber membrane includes a spinning step in which a polyolefin such as polyethylene and polypropylene is melt-spun to obtain a hollow shaped product, and a hollow shaped product obtained in the spinning step is drawn. And a stretching process for making it porous. In the spinning process, usually, the molten polyolefin resin is continuously spun from a nozzle having an annular opening, and cooling air is continuously supplied to the resin by a blower or the like in a cooling cylinder provided at the lower part of the nozzle. And a cooling step of cooling and solidifying to form a hollow shaped product. In this cooling process, the molten resin spun from the annular opening of the nozzle gradually decreases in diameter as it moves away from the nozzle, and when the molten resin is cooled and completely crystallized, the diameter becomes constant and finally constant. A hollow shaped article having a diameter of 5 mm is formed. In the stretching process, when a uniform hollow shaped product having a constant diameter and film thickness is used, yarn breakage in the stretching process hardly occurs and a homogeneous porous hollow fiber membrane can be stably obtained. By appropriately managing the state of the molten resin and the peripheral conditions in the region where the molten resin is spun from the nozzle and enters the cooling device until the diameter becomes constant, the diameter and film thickness can be reduced. It is desirable to produce a uniform and uniform hollow shaped product.

  Conditions such as the amount and direction of the cooling air when cooling air is blown into the molten resin to solidify it affect the uniformity of the film thickness and diameter of the resulting hollow shaped product. This is important because it affects the performance of the hollow fiber membrane obtained by stretching the shaped product. And what was described in patent document 1 is known as an apparatus for cooling and solidifying molten resin.

JP 2001-200422 A

  As described above, in order to produce a uniform hollow shaped article having a uniform diameter and film thickness, it is necessary to appropriately manage the state of the molten resin and the surrounding conditions in the region to be thinned in the spinning process. However, in the conventionally used method, the cooling environment in the cooling cylinder, that is, the atmospheric temperature in the cooling cylinder and the flow rate of the cooling air are adjusted by controlling the cooling device when introducing the cooling air into the cooling cylinder. It was possible.

  However, as a result, in order to determine whether or not the cooling environment of the molten resin is appropriate, the outer diameter value of the completed hollow shaped article is measured, and the suitability of the cooling environment is determined only from the outer diameter value. It was necessary to make judgments, which required skilled judgment and trial and error at the work site.

  In general, melt spinning equipment is operated almost all year round, so even if an appropriate cooling environment can be created once, the temperature of the molten resin or cooling gas may change due to environmental changes such as the outside temperature during operation. When changes occur, it is necessary to repeat trial and error to create an appropriate cooling environment.

  Accordingly, the present invention has been made to solve the above-described problems, and provides a melt spinning apparatus and a method for producing hollow fibers that can easily determine the suitability of a cooling environment in a region to be thinned. The purpose is to do.

  In order to solve the above-described problems, the present invention provides a melt spinning apparatus that applies a fluid having a temperature lower than that of the molten resin to the molten resin spun from the nozzle and solidifies the molten resin. And measuring means for measuring a physical property value of the molten resin or a physical property value around the molten resin, which varies depending on the cooling state of the molten resin.

  According to the present invention configured as described above, the physical property value of the molten resin or the physical property value around the molten resin can be measured by the measuring means, which varies depending on the cooling state of the molten resin in the region to be thinned. Based on this measurement result, it can be easily determined whether or not the cooling environment of the molten resin is appropriate.

  In the present invention, it is preferable that the measurement result of the measuring means is compared with a predetermined standard value to control at least one of the temperature and the flow rate of the cooling fluid discharged from the cooling device that supplies the cooling fluid. A control unit.

  According to the present invention configured as described above, the cooling device can be feedback-controlled based on the measurement result by the measuring means, and the cooling environment can be appropriately maintained.

  In the present invention, it is preferable that the nozzle includes a plurality of spinning ports, and a plurality of the cooling devices are provided corresponding to the spinning ports.

  According to the present invention configured as described above, it is possible to appropriately determine the cooling state for each molten resin flow.

  In the present invention, the physical property value of the molten resin is preferably the surface temperature of the molten resin. In the present invention, the physical property value of the molten resin is preferably the outer dimension of the molten resin. In the present invention, the physical property value of the molten resin is preferably the crystallinity of the molten resin. In the present invention, the physical property value around the molten resin is preferably the ambient temperature of the region to be thinned.

  Further, in order to solve the above-mentioned problems, the present invention applies a fluid having a temperature lower than that of the molten resin to the molten resin spun from the nozzle and solidifies it to form a hollow shaped article. A method for producing hollow fibers by winding a shaped article, wherein the physical property value of the molten resin or the physical property value around the molten resin changes depending on the cooling state of the molten resin in a region where the molten resin is thinned. A measuring step is provided.

  According to the present invention configured as described above, in the measuring step, it is possible to measure the physical property value of the molten resin or the physical property value around the molten resin, which changes depending on the cooling state of the molten resin in the region to be thinned. Therefore, it is possible to easily determine whether or not the cooling environment of the molten resin is appropriate based on the measurement result.

  As described above, according to the present invention, it is possible to easily determine the suitability of the cooling environment in the area to be thinned.

It is the schematic which shows the melt spinning apparatus by embodiment of this invention. It is sectional drawing which shows the spinning head and cooling device by embodiment of this invention. In embodiment of this invention, it is sectional drawing which shows the example using the sensor for measuring the surface temperature of molten resin, and ambient temperature as a measurement means. In embodiment of this invention, the example using the sensor for measuring the optical characteristic of molten resin as a measurement means is shown. In embodiment of this invention, the example using the sensor for measuring the optical characteristic of molten resin as a measurement means is shown. In embodiment of this invention, the example using the sensor for measuring the optical characteristic of molten resin as a measurement means is shown.

A method for producing a hollow fiber membrane according to an embodiment of the present invention is mainly obtained by spinning a molten resin in which a polyolefin resin such as polyethylene or polypropylene is heated to a melting point or more from a nozzle outlet, and forming a hollow shape. It has a spinning process for obtaining a shaped product and a stretching process for stretching the hollow shaped product. And a spinning process has a cooling process which sprays cooling gas on the outer peripheral surface of the spun hollow shaped product, and solidifies by cooling.
Hereinafter, a melt spinning apparatus used for carrying out the spinning process will be described in detail with reference to the drawings.

  FIG. 1 is a schematic view showing a melt spinning apparatus according to an embodiment of the present invention. The melt spinning apparatus 1 includes a spinning head 3 adapted to spin a melt-heated resin, a cooling device 5 for cooling the resin spun from the spinning head 3, and a hollow shape of the cooled and solidified resin. And a winder 7 for winding the shaped product. Such a melt spinning apparatus 1 drops the molten resin spun from the spinning head 3 according to gravity, and cools and solidifies it in the cooling device 5 in the process of dropping the molten resin, and cools and solidifies the hollow shaped article. Since the winding is performed, the spinning head 3 and the cooling device 5 are arranged in parallel with the falling direction of the molten resin, that is, aligned in the vertical direction.

  The cooling device 5 includes a measuring unit 9 for measuring a physical property value of the molten resin or a physical property value around the molten resin in the cooling device 5, a control unit 11 connected to the measuring unit 9, and a control unit 11. A quench blower 13 for feeding air as a cooling fluid into the cooling device 5 based on the control is provided.

  FIG. 2 is a cross-sectional view showing the spinning head and the cooling device. The spinning head 3 includes four spinning outlets 15 for spinning the molten resin. Each spinning port 15 opens downward and has a spinning port, and this spinning port is arranged on the circular bottom surface of the spinning head 3. The four spouts 15 are arranged so as to form a square apex.

  The cooling device 5 is disposed below the spinning head, and is configured to surround the molten resin flowing from the spinning head 3 in addition to the measurement unit 9, the control unit 11, and the quench blower 13 described above. A cooling cylinder 17 and an extension pipe 19 extending upward from the cooling cylinder 17 are provided.

  The cooling cylinder 17 extends in parallel with the dropping direction of the molten resin (vertically downward), and the upper end and the lower end are open. The cooling cylinder 17 is arranged on the lower side of the spinning head 3 so that the central axis thereof is coaxial with the central axis of the spinning head, and melts falling from the four spinning outlets 15 of the spinning head 3. The resin has such a diameter that it can pass from the upper end toward the lower end without touching the cooling cylinder 17. The cooling cylinder 17 cools and solidifies the molten resin by applying cooling air sent from the quench blower 13 to the molten resin while the molten resin passes through the cooling cylinder 17. Such a cooling cylinder 17 has a double pipe structure including an outer cylinder 21 and an inner cylinder 23 having a porous structure.

  The quench blower 13 is configured to send cooling air between the outer cylinder 21 and the inner cylinder 23 of the cooling cylinder 17 in a direction orthogonal to the extending direction of the cooling cylinder 17. Then, the cooling air that flows between the outer cylinder 21 and the inner cylinder 23 from the quench blower 13 spreads in the circumferential direction of the cooling cylinder 17 in the space between the outer cylinder 21 and the inner cylinder 23, and passes through the inner cylinder 23. Passes from the circumferential direction toward the center of the inner cylinder 23. Thus, the cooling device 5 performs so-called radial quenching in which the cooling air from the quench blower 13 is applied to the molten resin from the circumferential direction. Then, the cooling air that flows in the direction perpendicular to the falling direction of the molten resin and flows into the cooling cylinder 17 changes its direction in the cooling cylinder 17 and flows in the upper end direction or the lower end direction of the opened inner cylinder at a lower pressure. .

  The extension pipe 19 extends to the vicinity of the lower surface of the spinning head 3 in parallel with the dropping direction of the molten resin. The extension pipe 19 is configured to allow the cooling air that has flowed upward from the cooling cylinder 17 to flow further upward. Thereby, cooling air flows in the direction which opposes the falling direction of molten resin. The air reaching the upper end of the extension pipe 19 flows out of the pipe 25 from the gap between the extension pipe 19 and the spinning head 3.

  When the molten resin is spun from the nozzle 15 having the spinning outlet of the spinning head 3, the diameter of the molten resin gradually decreases as it falls. Here, the spinning outlet is preferably an annular opening. The diameter of the molten resin is constant at a certain point, and is wound by the winding device 7 as a hollow shaped article having a constant diameter below this point. The point where the diameter of the molten resin becomes constant is considered to be a position where the molten resin is sufficiently cooled and crystallized, and is usually in the cooling cylinder 17 or the extension pipe 19 of the cooling device 5. Crystallization is complete. Then, the melt spinning apparatus 1 determines the cooling behavior of the molten resin in the region R to be thinned from when the molten resin enters the cooling apparatus until the diameter becomes constant.

  Next, the measuring means 9 for measuring the physical property value of the molten resin or the physical property value around the molten resin will be described in detail.

  The physical property value of the molten resin that changes depending on the cooling state of the molten resin refers to the surface temperature, refractive index, infrared radiation amount, light transmission amount, crystallinity, polarization amount, etc. of the molten resin at an arbitrary position of the molten resin. The physical property value around the molten resin, which changes depending on the cooling state of the molten resin, refers to the atmospheric temperature, the amount of infrared radiation of the substance exposed to the atmosphere, the refractive index of the atmospheric gas, and the like. These physical property values are closely related to how much the molten resin exposed to the cooling air is cooled, and the measuring means 9 is configured to measure at least one of these. Yes. And the control part 11 is comprised so that the temperature and quantity of the cooling air supplied from the quench blower 13 may be adjusted based on the measurement result by the measurement means 9. FIG.

  FIG. 3 is a cross-sectional view showing an example in which a sensor for measuring the surface temperature of the molten resin and the ambient temperature is used as the measuring means.

  As shown in FIG. 3, the extension pipe 19 measures the radiation temperature sensor 27 for measuring the surface temperature of the molten resin in the region to be thinned, and the ambient temperature of the molten resin in the region R to be thinned. Electric heating pairs 29 and 31 are attached. The radiation temperature sensor 27 and the electric heat couples 29 and 31 are connected to the control unit 11, and the measurement result is transmitted to the control unit 11.

  The radiation temperature sensor 27 cuts out a part of the side wall of the extension pipe 19 to form a window 33, and continuously measures the surface temperature of the molten resin at an arbitrary fixed point through the window 33. The position of the fixed point may be any point in the region R to be thinned. Then, the control unit 11 compares the surface temperature of the molten resin at this fixed point with a predetermined temperature based on the measurement result by the radiation temperature sensor 27. As a result of the comparison, when the surface temperature of the molten resin at the fixed point is higher than the predetermined temperature, the control unit 11 determines that the molten resin is not sufficiently cooled, and cools from the quench blower 13. The temperature of the cooling air supplied to the cylinder 17 is lowered and / or the amount of the cooling air is increased. Thus, by feeding back the surface temperature of the molten resin to the temperature and amount of the cooling air supplied from the quench blower 13, the surface temperature of the molten resin at the fixed point can be kept constant.

  The electrothermal pairs 29 and 31 are arranged between the molten resin and the inner wall of the extension pipe 19 and at the center of the four molten resin flows. Each of the electrothermal pairs 29 and 31 transmits to the control unit 11 the atmospheric temperature at the fixed point between the molten resin and the inner wall of the extension pipe 19 and the atmospheric temperature at the central fixed point of the four molten resin flows. It is like that. And a control part compares the atmospheric temperature in this fixed point with the temperature determined beforehand based on the measurement result by the electrothermal pairs 29 and 31. FIG. As a result of the comparison, when the atmospheric temperature at the fixed point is higher than the predetermined temperature, the control unit 11 determines that the molten resin has not been sufficiently cooled, and the cooling cylinder 17 from the quench blower 13 is determined. Lowering the temperature of the cooling air supplied to and / or increasing the amount of cooling air. On the other hand, when the ambient temperature at this fixed point is lower than a predetermined temperature, the control unit 11 determines that the molten resin has been cooled too much and is supplied from the quench blower 13 to the cooling cylinder 17. Increase the temperature of the cooling air and / or reduce the amount of cooling air. Thus, by feeding back the surface temperature of the molten resin to the temperature and amount of the cooling air supplied from the quench blower 13, the surface temperature of the molten resin at the fixed point can be kept constant.

  In the example shown in FIG. 3, the extension tube 19 is provided with the radiation temperature sensor 27 and the plurality of electric heating pairs 29, 31, but either the radiation temperature sensor 19 or the plurality of electric heating pairs 29, 31 is attached. You may make it like, and you may make it attach one electrothermal pair.

  4 to 6 show an example in which a sensor for measuring the optical characteristics of the molten resin is used as the measuring means. The examples shown in FIGS. 4 to 6 show a melt spinning apparatus configured to determine the cooling state of the molten resin by measuring the polarization state of the molten resin.

  In the example shown in FIG. 4, a light guide 35 such as a light guide made of GF (Glass Fiber) is attached to the center of the nozzle 15 having an annular opening (the center of the annular opening). One end of the light guide 35 is exposed downward from the annular opening and the center, and is configured to be incident from the other end and emit light toward the flow direction of the molten resin. The light emitted from one end of the light guide 35 travels through the hollow portion of the hollow molten resin flow. In addition, a CCD camera 37 is provided outside the extension tube 19 so as to take an image from the horizontal direction. The CCD camera 37 images a fixed point of a region where the molten resin is thinned through a window 33 in which a part of the extension tube 19 is made of a transparent material, for example.

  When the molten resin is spun from the spinning nozzle 3, it is in a liquid state, so even if light that travels substantially parallel to the flow direction of the molten resin hits the molten resin, the direction orthogonal to the flow direction of the molten resin That is, light is not scattered in the horizontal direction. However, as the molten resin is solidified and crystallized, the light hitting the molten resin is easily scattered, and the scattering of light in the horizontal direction increases as the molten resin solidifies. Therefore, by measuring the intensity of the scattered light from the molten resin from the horizontal direction at the fixed point of the region R to be thinned substantially corresponding to the range in which the molten resin is proceeding, the crystallization of the molten resin is performed. You can know the degree of progress.

  Then, the control unit 11 compares the intensity of the scattered light at this fixed point with a predetermined intensity based on the image captured by the CCD camera 37. As a result of the comparison, when the intensity of the scattered light at this fixed point is stronger than the predetermined intensity, the control unit 11 has excessively cooled the molten resin because the crystallization of the molten resin has progressed too much. The temperature of the cooling air supplied from the quench blower 13 to the cooling cylinder is increased and / or the amount of cooling air is decreased. On the other hand, when the intensity of the scattered light at the fixed point is weaker than a predetermined intensity, the control unit 11 determines that the molten resin is not sufficiently cooled because crystallization of the molten resin is delayed. Then, the temperature of the cooling air supplied from the quench blower 13 to the cooling cylinder 17 is lowered and / or the amount of the cooling air is increased. In this way, the degree of progress of the crystallization of the molten resin is determined from the light scattering intensity of the molten resin, and the determination result is fed back to the temperature and amount of the cooling air supplied from the quench blower 13, thereby melting at the fixed point. The degree of progress of crystallization of the resin can be kept constant.

  In the example shown in FIG. 5, the light emitting element 39 and the light receiving element 41 are attached to the same horizontal plane of the extension tube 19. The light emitting element 39 and the light receiving element 41 are arranged so as to sandwich a molten resin flow passing through the inside of the extension tube 19, and are arranged so that light emitted from the light emitting element 39 in the horizontal direction hits the molten resin. The light receiving element 41 is connected to the control unit 11 and is configured to transmit the detection result of light from the light emitting element 39 to the control unit 11.

  As shown in FIG. 5A, when the crystallization of the molten resin has already been completed at the height of the horizontal plane where the light emitting element 39 and the light receiving element 41 are arranged, the light from the light emitting element 39 is Since it does not pass through the molten resin, it does not reach the light receiving element 41. On the other hand, as shown in FIG. 5B, when the crystallization of the molten resin is not completed at the level of the horizontal plane where the light emitting element 39 and the light receiving element 41 are arranged, the light from the light emitting element 39 is emitted. At least a part of the light passes through the molten resin and reaches the light receiving element 41. Therefore, by setting in advance a threshold value related to the light detected by the light receiving element 41 in the control unit 11, it is possible to determine the degree of progress of crystallization of the molten resin as in the example shown in FIG.

  Further, in the example shown in FIG. 6, the light emitting element 43 and the light receiving element 45 are attached to the extension tube 19 side by side in the vertical direction. In this example, the progress of crystallization of the molten resin can be determined by the degree of light reflection of the molten resin. That is, as shown in FIG. 6A, when light emitted from the light emitting element 43 obliquely downward toward the molten resin strikes the molten resin at a position lower than the molten resin crystallization completion position, the light emitting element Most of the light emitted at 43 can be detected by the light receiving element 45. On the other hand, as shown in FIG. 6B, when the light emitted from the light emitting element 43 hits the molten resin at a position higher than the crystallization completion position, most of the light emitted from the light emitting element 43 is Since it passes through the molten resin, it is not reflected toward the light receiving element 45. Therefore, in this case, the light receiving element 45 cannot detect the reflected light from the molten resin, and even if it can be detected, the light intensity is weak. Accordingly, by setting a threshold value relating to the intensity of the reflected light from the molten resin, which is detected by the light receiving element 45 in the control unit 11, the degree of progress of crystallization of the molten resin is determined in the same manner as in the example shown in FIG. can do.

  In any of the examples shown in FIGS. 5 and 6, the control unit 11 determines the light intensity at the fixed point and the predetermined light intensity based on the light detection results in the light receiving elements 41 and 45. Compare. As a result of the comparison, when the light intensity at the fixed point is higher than the predetermined intensity, the control unit 11 has excessively cooled the molten resin because the crystallization of the molten resin has progressed too much. The temperature of the cooling air supplied from the quench blower 13 to the cooling cylinder 17 is increased and / or the amount of cooling air is decreased. On the other hand, when the intensity of light at this fixed point is weaker than a predetermined intensity, the control unit 11 determines that the molten resin is not sufficiently cooled because the crystallization of the molten resin is delayed. Thus, the temperature of the cooling air supplied from the quench blower 13 to the cooling cylinder 17 is lowered and / or the amount of the cooling air is increased. In this way, the degree of progress of the crystallization of the molten resin is determined from the light scattering intensity of the molten resin, and the result of the determination is fed back to the temperature and amount of the cooling air supplied from the quench blower. The degree of progress of crystallization can be kept constant.

  As described above, according to the melt spinning apparatus 1, since the physical property value of the molten resin or the physical property value around the molten resin can be measured by the measuring means 9, the cooling state of the molten resin can be easily known. Furthermore, according to the melt spinning apparatus 1, since the quench blower 13 can be feedback-controlled based on the measurement result by the measurement means 9, it is possible to appropriately maintain the cooling environment and create a uniform hollow shaped article. it can.

  In addition, this invention is not limited to the above-mentioned embodiment, Each structure of the above-mentioned embodiment can be suitably changed in the range which does not deviate from the meaning of this invention.

For example, in the above-described embodiment, the measuring unit 9 is attached to the extension pipe 19, but the region to be thinned after the molten resin enters the cooling device 5 (extension pipe 17) until the diameter becomes constant. Any position may be used as long as the physical property value of the molten resin or the physical property value around the molten resin can be measured.
In the above-described embodiment, air is used as the cooling fluid. However, a single component gas such as nitrogen gas, a mixed gas, or the like may be used.
As in the above-described embodiment, it is more preferable to spin and wind the molten resin from the top to the bottom in the vertical direction. The form may be wound in the horizontal direction with respect to the delivery spinning outlet.
Although it is preferable to use a nozzle spout having an annular opening, the present invention is not limited to this, and hollow fibers such as a spout that is not completely opened in a ring can be spun. If it is, shape will not be specifically limited.

DESCRIPTION OF SYMBOLS 1 Melt spinning apparatus 3 Spinning head 5 Cooling apparatus 9 Measuring means 11 Control part 13 Quench blower 15 Nozzle 27 Radiation temperature sensor 29, 31 Electrothermal pair 37 CCD camera 39, 43 Light emitting element 41, 45 Light receiving element

Claims (9)

A melt spinning device that applies a fluid having a temperature lower than that of the molten resin to the molten resin spun from the nozzle and solidifies the molten resin,
A melt spinning apparatus for hollow fibers, comprising measuring means for measuring a physical property value of a molten resin or a physical property value around the molten resin, which varies depending on a cooling state of the molten resin in a region where the molten resin is thinned.   The control part for comparing at least one of the temperature or flow volume of the cooling fluid discharged | emitted from the cooling device which compares the measurement result by the said measurement means with a predetermined standard value, and supplies the cooling fluid. 2. The melt spinning apparatus according to 1. The nozzle includes a plurality of spinning outlets,
The melt spinning apparatus according to claim 1 or 2, wherein a plurality of the cooling devices are provided corresponding to each spinning outlet.   The melt spinning apparatus according to claim 1, wherein the physical property value of the molten resin is a surface temperature of the molten resin.   The melt spinning apparatus according to any one of claims 1 to 3, wherein the physical property value of the molten resin is an outer dimension of the molten resin.   The melt spinning apparatus according to any one of claims 1 to 3, wherein the physical property value of the molten resin is a crystallinity of the molten resin.   The melt spinning apparatus according to any one of claims 1 to 3, wherein the physical property value around the molten resin is an ambient temperature of a region to be thinned. A method for producing a hollow fiber by making a hollow shaped article by applying a fluid having a temperature lower than that of the molten resin to a molten resin spun from a nozzle and solidifying the hollow shaped article, and winding the hollow shaped article Because
A method for producing a hollow fiber comprising a step of measuring a physical property value of a molten resin or a physical property value around the molten resin, which varies depending on a cooling state of the molten resin in a region where the molten resin is thinned.   The method for producing a hollow fiber according to claim 8, comprising the step of comparing the measured cooling state with a predetermined standard value and controlling at least one of a temperature or a flow rate of the supplied cooling fluid.

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