JP4354869B2 - Method and apparatus for freezing treatment of fiber bundle for producing ultrashort fiber - Google Patents

Description

  In order to obtain a fiber bundle which is a raw material for producing ultrashort fibers having a fiber length of 0.1 mm or less and bundles a large number of single filaments and freezes, a fiber bundle immersed in water is freeze-treated. The present invention relates to a method and an apparatus thereof.

  Conventionally, in order to obtain a short fiber having a length of several mm to several tens of mm by bundling a long single fiber group made of a thermoplastic synthetic polymer such as polyester and polyamide into a fiber bundle and cutting the fiber bundle, Fiber bundle cutting devices are commonly used. For example, as such a cutting device, a fiber bundle is wound around a cutter roller having a large number of cutting blades radially provided, and a predetermined length is continuously applied while pressing the thick fibers wound on the cutting blade against the cutting blade. A roller cutter type fiber bundle cutting device that cuts the blade is used. A so-called guillotine cutter type fiber bundle cutting device has also been known for a long time, in which a fixed blade and a moving blade are provided as shear blades, and a fiber bundle is extruded between the shear blades by a predetermined cutting length.

  In an environment where such a conventional fiber bundle cutting device is used, recently, it is used as an extremely short synthetic fiber to be used as a paint or to be mixed in cosmetics, or a floc processed product having a soft texture. As the demand for ultrafine fibers or elastic fibers cut shortly increases, a cut fiber length of 0.1 mm to several mm has been required. However, when trying to obtain a fiber having a short fiber length, for example, in the case of the former roller cutter type fiber bundle cutting device, the interval between adjacent cutting blades of the cutting blade group provided radially on the rotating cutter roller is extremely small. It is required to do. However, when this is done, the fibers cut between the cutting blades are clogged, making it difficult to discharge them, as well as the problem of the thickness of the cutting blade itself, so there is a limit to shortening the cutting fiber length. .

  However, in the case of the latter guillotine cutter type fiber bundle cutting device, it is possible to cope with a cutting fiber length of about 0.5 mm. However, when trying to cut a fiber having a small single fiber fineness using such a conventional fiber bundle cutting device, the fiber is bent or buckled due to the elasticity of the fiber itself, and is perpendicular to the fixed blade. Or the clearance between the fixed blade and the movable blade becomes extremely difficult to adjust, resulting in a large amount of miscuts such as oblique cuts and uneven cutting lengths. Even in such a case, when trying to obtain a short fiber with a constant cut length of the fiber, it is possible to select and take out only those that have been cut normally from a large number of miscut fibers. Required. However, the operation is extremely complicated, and when the number of miscut fibers that do not fit within the allowable cut length increases, the yield of normally cut fibers themselves deteriorates.

  Then, the apparatus for solving the said problem which a guillotine cutter type fiber bundle cutting device has is proposed by Unexamined-Japanese-Patent No. 2003-11962, for example. In this prior art, a guide for performing the role of wrapping the fiber bundle with the sheet-like material is attached in front of the cutting portion for cutting the fiber bundle to be supplied, and the guide is obtained by running the continuous sheet-like material along with the fiber bundle. The sheet-like material is piled up so as to wrap the fiber bundle through a roller and cut together with the fiber bundle. And by doing in this way, the fiber bundle wrapped with the sheet-like material is sent to the cutting portion in a straight line in a straight line state with the fibers being aligned by the action of the sheet-like material, and is miscut. It is cut to the required length without any problems.

  However, even if such a guillotine cutter type fiber bundle cutting device is used, the fiber length that can be cut is 0.1 to 30 mm, and it is extremely difficult to stably obtain cut fibers of less than 0.1 mm. . Moreover, as a sheet-like material used to coat the fiber bundle in order to obtain such short fibers, organic polymer films such as paper, polyolefin, polyester, and cellophane, fabrics, and nonwoven fabrics must be used.

  However, when such a sheet-like material is used, it is required to separate the cut fiber and the sheet-like material after cutting. However, it is difficult to completely separate them, and the amount is small. However, there is a possibility of mixing into the cut fiber. In addition, as the cut fiber length approaches 0.1 mm, the sheet-like material that can be used is required to be more rigid, and the bundle diameter of the fiber bundle that can be cut further increases the productivity. It cannot be increased to the diameter, and it is necessary to reduce it. This is because once a large number of single fiber groups are bundled to form a thick fiber bundle, a strong binding force is exerted on the single fiber group constituting the fiber bundle even if the fiber bundle is wrapped with a film-like sheet. This is because it is not easy to act, and for this reason, a single fiber group in a state where it can move freely is partially generated. Therefore, it is not easy to cut this short. Then, since the production efficiency is greatly reduced, it is not preferable from the viewpoint of production efficiency, and even if such a conventional technique is used, it is still difficult to obtain a cut fiber length of substantially 0.1 mm. is there.

  In addition, when considering the prior art only from the viewpoint of restraining the fiber, the aramid fiber, which is difficult to cut by a conventional cutting device, was impregnated with a molten thermoplastic resin, and the entire fiber was cured and cured. Japanese Patent Laid-Open No. 63-35829 proposes a technique for pelletizing a resin with a pelletizer. However, this prior art does not need to remove the impregnated thermoplastic resin to the last, and is intended to obtain a fiber reinforced plastic in which shortcut fibers are kneaded as they are. Only the cut fibers are isolated and taken out. It is not a thing.

  Further, this conventional technique is essentially a technique of pelletizing a thermoplastic resin even if a shortcut fiber is included. Therefore, in this prior art, as described in the above publication, even if the shortcut fiber can be kneaded into the thermoplastic resin, the thermoplastic resin and the shortcut fiber are separated from each other and taken out. This is not easy, and in fact, this is not expected at all. In addition, as described above, this conventional technique is to pelletize the fiber after impregnating the fiber with a thermoplastic resin. The fiber-containing resin is cut into a cutting length of less than 0.1 mm by a known pelletizer and pelletized. It is extremely difficult.

  Furthermore, in order to increase the productivity of short fibers, it is required to bundle a very large number of elongated single fibers into a fiber bundle having a total fineness exceeding 10,000 dtex and harden with a thermoplastic resin. However, it is extremely difficult to sufficiently impregnate a fiber bundle having such a large diameter with a thermoplastic resin having a high viscosity. In addition, if bubbles are present inside the thermoplastic resin, it is extremely difficult to remove the bubbles from the resin, and the single fiber group in the portion where the bubbles are present is not restrained by the resin. Therefore, it cannot be avoided that a single fiber group that cannot be restrained by the thermoplastic resin is partially generated inside the fiber bundle, and miscuts are inevitably increased.

JP 2003-11962 A JP-A-63-35829

  The present inventor first discovered that it is extremely difficult to produce ultrashort fibers having a fiber length of less than 0.1 mm without miscutting by the conventional technology as described in the “Background Art” column. In the present invention, with respect to the terms “embedding agent” and “embedding material”, the case of being in a liquid state or gas state is referred to as “embedding agent”, and the case of being in a solid state is referred to as “embedding material”. That's it. Then, it is embedded in an embedding material such as ice (embedding material) obtained by freezing fiber bundles made up of a large number of single fiber groups with water (embedding agent) or dry ice obtained by solidifying carbon dioxide gas. A series of inventions for obtaining ultrashort fibers having a fiber length of less than 0.1 mm by cutting the end face of the fiber bundle subjected to the embedding treatment into a flake shape with a cutting blade is completed. Has already filed a patent application.

  However, when water is used as the embedding agent and this water is frozen and the fiber bundle is embedded with ice as the embedding material, a thermoplastic resin having a high melt viscosity is used as the embedding material as in the prior art. The present inventor has found that it is very difficult to remove air bubbles when freezing water even if extremely low viscosity water is used as an embedding agent without using it.

This is because water has an air solubility of 2.78 × 10 ⁻² in the atmosphere of 0 ° C., but since the solubility of air in ice is zero, the air dissolved in water is solidified. This is because it will exist as a gas in ice. Moreover, since the density of water becomes maximum at 4 ° C., the water at 0 ° C. is pushed upward and begins to freeze from the water surface. In this way, once the water surface is frozen, the air dissolved in the water below the water surface loses its escape and becomes trapped in the water. In addition, since the air dissolved in the water along with freezing is pushed out into the unfrozen water, the concentration of dissolved air in the unfrozen water increases. As a result, the air dissolved in the unfrozen water finally becomes bubbles, and when the bubbles lose their escape by the ice generated above and the whole water is frozen, the bubbles remain in the ice.

  However, if air bubbles are mixed in the ice that is the embedding material, a problem arises that miscuts are caused without restraining the single fiber group in the portion where the air bubbles are present. Therefore, the object of the present invention is to solve the problems described in the “Background Art” column, and to fix the single fiber group constituting the fiber bundle with water that has been frozen. An object of the present invention is to provide a fiber bundle freezing treatment method and an apparatus for producing a large amount of ultrashort fibers with a small yield and a high yield by reducing bubbles present in a certain ice as much as possible.

  The present invention has been made as a result of intensive studies in order to solve the above problems, and the present invention is completed while searching for a technique for freezing a fiber bundle so that bubbles do not exist in ice as much as possible. Has been reached.

Here, as an invention related to the freezing treatment method very short fibers for manufacturing fiber bundle, the fiber bundle together bundled aligned drawn so as to be parallel to the fiber longitudinal direction "a large number of single fiber group according to claim 1 When freezing and producing the ultrashort fiber by cutting the frozen fiber bundle into a thin piece, the fiber bundle is immersed in water filled in an ice container, and immersed in water. A method of freezing fiber bundles for producing very short fibers for freezing fiber bundles, wherein the water surface part is heated to prevent freezing of the water surface part while exhausting air on the water surface from above the ice container. However, there is provided a method for freezing a fiber bundle for producing ultrashort fibers, which freezes water filled in the freezing container.

  At this time, as in the invention described in claim 2, “for air exhaust on the water surface is performed under a weak negative pressure of 30 to 650 torr, for producing ultrashort fibers according to claim 1, It is preferable to use the “freezing treatment method for fiber bundles”.

  Further, as in the invention according to claim 3, “freezing of the fiber bundle for producing ultrashort fibers according to claim 1 or 2, characterized in that the freezing vibration is applied to the freezing container and the freezing treatment is performed. It is preferable to use a “treatment method”.

  And, as in the invention according to claim 4, the fiber bundle for producing ultrashort fibers according to any one of claims 1 to 3, wherein the water used for the freezing treatment is degassed in advance. It is preferable to use the “freezing treatment method”.

Next, as an invention related to the freezing treatment method very short fibers for manufacturing fiber bundle, the fiber bundle together bundled aligned drawn so as to be parallel to the fiber longitudinal direction "a large number of single fiber group according to claim 5 When freezing and producing the ultrashort fiber by cutting the fiber bundle subjected to the freezing treatment into a flake shape, the freezing container which is filled with water for standing the fiber bundle and immersing the fiber bundle, and the freezing container A lid member that is provided at the top of the container and that keeps the inside of the container airtight, a heating device that heats the upper part of the water including the water surface portion filled in the icing container so as not to freeze, and for cooling the icing container And a freezing apparatus for fiber bundles for producing ultrashort fibers, which includes at least the refrigeration apparatus and an exhaust apparatus attached to the lid member.

  At that time, as in the invention described in claim 6, “freezing treatment of the fiber bundle for producing ultrashort fibers according to claim 5, comprising a gas-liquid separator between the lid member and the exhaust device”. An “apparatus” is preferred.

  In addition, as described in claim 7, "the apparatus for freezing a fiber bundle for producing ultrashort fibers according to claim 5 or 6 comprising a microvibration generating apparatus for imparting microvibration to the freezing container" It is preferable that

  According to the above-described method for freezing a fiber bundle for producing ultrashort fibers according to claim 1 and the apparatus for freezing a fiber bundle for producing ultrashort fibers according to claim 5, the ice container is filled. When freezing a fiber bundle that has been allowed to stand in water, the upper portion of the freezing container is heated, so that this portion does not freeze. Therefore, even if a gas such as air dissolved in water during the freezing process is bubbled, the bubbled gas can be discharged from above without being trapped in the ice.

  For this reason, air bubbles do not remain in the fiber bundle portion subjected to the icing treatment, the single fiber groups constituting the fiber bundle are reliably restrained by ice, and there is no portion that is not restrained because the air bubbles remain. Then, when the single fiber group constituting the fiber bundle is cut into a thin piece with the cutting blade, the cutting force can be sufficiently applied to each single fiber, for example, a fiber of 0.1 mm or less It is possible to produce a large amount of ultrashort fibers having a long yield without miscutting.

  In addition, when the freezing process is started without heating the water surface of the freezing container as in the present invention, the water in the freezing container starts to freeze from the surroundings including the water surface. As a result, unfrozen water is trapped inside the frozen ice, and when freezing of the water trapped inside begins, internal stress is generated due to volume expansion accompanying the phase change at this time. Defects such as cracks and cracks will occur. Of course, if such a defect occurs, it goes without saying that it causes a miscut when producing a very short fiber by cutting a fiber bundle that has been frozen.

  On the other hand, according to the present invention, at the time of freezing treatment, the water surface portion can be frozen from the bottom portion of the freezing container gradually upward without being frozen, and finally the water surface portion can be frozen. For this reason, internal stress is released to the upper part where freezing proceeds, there is almost no internal stress due to volume expansion that occurs when water changes to ice during freezing, and there is no residual stress, the above-mentioned problem Is resolved.

  According to the second aspect of the present invention, air on the water surface can be forcibly sucked and exhausted from a water surface that is not frozen to a low negative pressure of 30 torr to 650 torr. It is possible to positively exhaust the gas such as converted air from the water and exhaust it. Therefore, it is possible to prevent the bubbles from being contained in the fiber bundle subjected to the icing treatment.

  In addition, as in the invention described in claim 3 or claim 7, if a freezing vibration generating device is provided and a freezing treatment is performed while giving a freezing vibration to the freezing container before or during the freezing treatment, the freezing container vibrates. At the same time, the air adhering to the fiber bundle can be separated from the fiber bundle by the action of the vibrating water. At the same time, it is possible to promote the coalescence of minute gases such as aerated air, and to promote the upward movement of the air bubbles due to an increase in buoyancy received by the air bubbles. As a result, it is possible to obtain a frozen fiber bundle free from white turbidity and having almost no transparent bubbles.

  Further, as in the invention described in claim 4, by separately degassing the water filled in the icing container in advance, bubbles generated during the icing process can be reduced. For this reason, it is effective at the point which eliminates the bubble which remains in the fiber bundle which carried out freezing treatment.

  Further, as in the freezing treatment apparatus according to claim 6, the apparatus of the present invention includes a gas-liquid separator between the lid member and the exhaust device, so that the water filled in the freezing container is It is possible to trap water droplets or the like that may accompany vibrations or when air on the water surface is sucked in a weak vacuum such as a low negative pressure of 30 to 650 torr, and a good exhaust operation can be performed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Here, FIG. 1 is a schematic configuration diagram illustrating the configuration of the apparatus in order to schematically explain the method and the apparatus of the present invention, in which a part is given a cross section.

  In FIG. 1, 1 is a freezing device, 2 is a freezing container, 3 is a fiber bundle, 4 is a fixture, 5 is a decompression chamber, 6 is a gas-liquid separator, 8 is an exhaust device, 9 is a heating device, and 10 is a fine device. A vibration generator and 11 indicates a control device. In addition, the part enclosed with the dashed-two dotted line in FIG. 1 is the freezing apparatus 1 comprised, for example by a freezer etc., Comprising: The water (embedding agent) which immersed the fiber bundle 3 left still in the freezing container 2 In this way, the fiber bundle 3 is embedded by the embedding material (ice). The refrigeration apparatus 1 is not limited to the illustrated freezer, and may be a system in which the icing container 2 is immersed in a refrigerant bath.

  Here, as the fiber bundle 3, in the present invention, a fiber having a total fineness of 10,000 to 10 million dtex in which a large number of long single fiber groups are bundled together in one direction so as to be parallel to each other in the fiber longitudinal direction. A bundle 3 is preferably prepared. And the fiber bundle 3 prepared in this way is formed by fixing both ends of the fiber bundle 3 while maintaining the aligned state by the fixture 4 and then cutting both ends outside the fixture 4. . Then, the fiber bundle 3 is left in a state of being suspended in an icing container 2 filled with water that has been separately deaerated while being fixed by the fixture 4.

  At this time, a decompression chamber 5 that also serves as a lid member for the freeze container 2 is provided above the freezing container 2, and the decompression chamber 5 is heated around the decompression chamber 5 during the freezing process. A heating device 9 is attached. The heating device 9 is provided for delaying icing from the water surface formed by water filled in the icing vessel 2. That is, the role of the heating device 9 is that the density of water supplied to the freezing treatment is maximum at 4 ° C., so that the water at 0 ° C. is pushed by the lid member portion of the freezing container 2 above, Plays a role in preventing freezing from the formed water surface.

  This is because if the water surface formed on the lid member portion of the icing container 2 freezes, the air dissolved in the lower water has a concentration of air dissolved in the water as ice is formed on the water surface. This is because the bubbled air is bubbled up in the water, but the bubbled air is prevented from escaping by the ice already generated upward. However, if the heating device 9 heats the lid member portion of the icing container 2 to prevent icing of the water surface at the lid member portion, the air bubbled from the unfrozen water surface can be easily removed. It can be escaped.

The air dissolved in the water when the water in the freezing container 2 freezes is bubbled, although water has an air solubility of 2.78 × 10 ⁻² at 0 ° C. in the atmosphere. This is because the solubility of air in ice in which water has been frozen is zero, so that air dissolved in water will exist as a gas in ice as water freezes.

  At that time, since the lid member portion also serves as the decompression chamber 5, if the air bubbled from the decompression chamber 5 is exhausted, when the entire water in the freezing container 2 has been frozen, the air bubbles are formed. Air does not remain in the ice. In addition, since the heating apparatus 9 plays such an important role, it is preferable to control the heating temperature and the heating time so that the heating temperature and the heating time can be arbitrarily set. Is preferably provided.

  At this time, it is preferable that the heating temperature and the heating time by the heating device 9 are determined by experiments or the like. This is because it is not meaningful to operate the heating device 9 after the freezing of the entire water filled in the freezing container 2 by the freezing device 1 is completed, and on the contrary, the continuous use of the freezing device 1 is also required. This is disadvantageous in terms of running costs. In addition, in the manufacturing process of a very short fiber, both ends of the fiber bundle subjected to freezing are cut off by a cutter. For this reason, there is not much significance in continuing the freezing operation until the entire water filled in the freezing container 2 completes freezing. If the freezing treatment of the fiber bundle 3 has already been completed up to the part cut by the cutter, As mentioned above, it is not necessary to continue the freezing process of the fiber bundle 3.

  Next, in the present invention, after the gas-liquid separator 6 for separating the gas and the liquid is attached to the rear stage side of the decompression chamber 5, the exhaust including the vacuum pump, the exhaust fan, and the like through the exhaust pipe 7. It is preferable that the air present in the decompression chamber 5 on the water surface is exhausted by the device 8 under a weak negative pressure of 30 to 650 torr. Here, it is preferable to place the degree of decompression inside the decompression chamber 5 under the above-described weak negative pressure. To make the degree of decompression too large, evaporation of water filled in the ice container 2 is reduced. This is because it is not a good idea because it promotes more than necessary and increases the cost of equipment and operation for constructing equipment having such a capability. On the other hand, if the degree of decompression is too low, the effect of expelling air bubbled into water during the icing process is reduced, which is not preferable.

  Thus, in the present invention, moisture is removed from the air containing water droplets sucked and exhausted from the decompression chamber 5, and only the air is exhausted from the exhaust pipe 7 to the outside through the exhaust device 8. Therefore, bubbles generated in the deaerated water in the frozen container 2 of the fiber bundle 3 filled with separately deaerated water, or fibers when the fiber bundle 3 is left in the frozen container 2. The gas brought in with the bundle 3 is continuously and intermittently sucked and exhausted even during the freezing process.

  According to the apparatus of the present invention described above, since the suction and exhaust can be efficiently performed continuously during the freezing process (embedding process), the air bubbled during the freezing process can be exhausted well. it can. However, along with such operations, air dissolved in water in the freezing container 2 is actively bubbled, and this is combined to grow to increase buoyancy, and is maintained in an unfrozen state by heating. In order to facilitate escape from the water surface, it is preferable to slightly vibrate the ice container 2. Further, by finely vibrating the fiber bundle 3 and water, the air adhering to the fiber bundle 3 can be separated from the surface of the fiber bundle, which is also extremely effective in this respect. It should be noted that “micro-vibration” referred to in the present invention includes “ultra-sonic vibration” in which an ultrasonic wave is applied to vibrate.

  Therefore, in order to generate such a slight vibration, a minute vibration generator 10 that can be easily attached to and detached from the frozen container 2 is attached to an arbitrary position on the side surface or the lower surface of the frozen container 2. 10 gives a slight vibration to the entire ice container 2. In addition, as such a micro vibration generator 10, well-known micro vibration generators, such as an electromechanical vibrator and an acoustic vibrator, can be used. At that time, the vibration frequency and amplitude generated by the microvibration generator need to be changed depending on conditions such as the size and shape of the ice container 2 or the total fineness of the fiber bundle 3. It is preferable to be able to arbitrarily change the value of.

As described above, the fiber bundle 3 is subjected to freezing treatment in the state where the fine vibration generator 10 is attached to the freezing container 2, and the density of water at 0 ° C. is 0.9998 g / cm ³ , whereas since ℃ density of ice is 0.917 g / cm ^3, since water is approximately 10% of the volume when it comes into ice expands, it is necessary to take this into account. For this reason, when the water in the ice container 2 having a constant volume freezes, defects such as cracks and cracks due to internal stress accompanying the volume expansion of ice may occur. If defects such as cracks and cracks occur in the frozen ice, the end surface of the fiber bundle 3 that has been subjected to icing is cut into a thin piece to produce excellent short fibers having a fiber length of less than 0.1 mm. It becomes an obstacle in.

  In the present invention, since the freezing container 2 is installed in the refrigeration apparatus 1, the internal water begins to freeze from the wall surface side of the freezing container 2, but the lid member is heated by the heating device 9 as described above. So, this part of the water will freeze at the end. Therefore, the ice growth gradually occurs from the bottom wall surface side of the freezing vessel 2 and, furthermore, the fine water is given to the unfrozen water, so that the freezing of the water in the freezing vessel 2 Except, it progresses from the bottom part and the side part of the ice container 2 to the upper part where the lid member exists.

  On the other hand, when the apparatus of the present invention is not used, icing starts from the upper part including the water surface and the wall surface of the icing container 2 so as to surround the surroundings of unfrozen water, and icing gradually progresses toward the inside. To do. For this reason, when freezing of unfrozen water confined in the interior starts, defects such as cracks and cracks occur due to internal stress accompanying the volume expansion of the ice at this time. However, in the present invention, for the reasons described above, unfrozen water can freely move upward during freezing, so that internal stress accompanying volume expansion when water changes to ice is reduced. It is possible to prevent the occurrence of defects such as cracks and cracks.

  Of course, freezing treatment of the water in the freezing vessel 2 in this way is that the air dissolved in the freezing water is bubbled into unfrozen water, and the water containing the bubbled air is finally added. Freezing is also extremely effective in eliminating bubbles in the ice that is the embedding material. Then, the dissolved gas is frozen as bubbles around the fiber bundle 3, and this is cut with a cutting blade, for example, an ultrashort fiber having a fiber length of 0.1 mm or less is not miscut. Mass production with high yield is possible.

  As described above, in the present invention, a slight vibration is applied to the water in the freezing vessel 2 with a constant temperature gradient between the upper and lower sides of the freezing vessel 2 or 50 revolutions per minute. It is a preferred embodiment to freeze with stirring. At this time, for example, the temperature of the bottom part and the side part of the freezing container 2 is cooled to −1 ° C. to −20 ° C., and the temperature of the upper part (lid member part) of the freezing container 2 is heated to 0 ° C. to 5 ° C. It is preferable. As a result, the bottom and side portions of the freezing container 2 are kept at a predetermined low temperature, and the top is kept at a predetermined high temperature. As a result, water freezes upward from the bottom of the freezing container 2. The converted air is not confined in the ice container 2.

  At that time, since the water in the icing container 2 is constantly moved by the microvibration generator 10 or the like, bubbles that are about to be trapped by the ice that has started icing are repelled and returned to unfrozen water. For this reason, the fiber bundle 3 finally embedded by the bubble-free and transparent ice is completed. In addition, about the temperature gradient mentioned above, the temperature which cooled the bottom part of the freezing container 2 was made into -1 degreeC--20 degreeC (preferably -2 degreeC--5 degreeC). This is because it becomes too gentle and does not freeze from the bottom of the freezing container 2. The decompression chamber 5 also serving as a lid member is heated so that the water temperature in this portion is 0 ° C. to 5 ° C. (preferably 0 ° C. to 2 ° C.). This is because freezing starts from the top of the air bubbles, and bubbles cannot escape to the top.

  According to the method and apparatus for freezing a fiber bundle for producing ultrashort fibers according to the present invention, it is possible to produce an iced fiber bundle in which almost no bubbles are present inside the fiber bundle subjected to the freezing treatment. For this reason, when producing an ultrashort fiber by cutting the end portion of the fiber bundle that has been subjected to icing in this manner, a high yield can be obtained in a large amount without miscutting, for example, an ultrashort fiber having a fiber length of 0.1 mm or less. It is possible to provide a manufacturing method and a manufacturing apparatus of a frozen fiber bundle that can be manufactured.

It is the outline apparatus block diagram which showed typically the example of 1 embodiment of the freezing treatment apparatus of the fiber bundle for ultra-short fiber manufacture of this invention.

Explanation of symbols

1: Freezing apparatus dedicated to freezing production 2: Freezing container 3: Fiber bundle 4: Fixing tool 5: Decompression chamber (lid member)
6: Gas-liquid separator 8: Exhaust device 9: Heating device 10: Micro vibration generator 11: Control device

Claims (7)

When producing a very short fiber by freezing a fiber bundle in which a large number of single fiber groups are aligned and bundled so as to be parallel to each other in the longitudinal direction of the fiber, and cutting the frozen fiber bundle into a thin piece, A method for freezing a fiber bundle for producing ultrashort fibers that are immersed in water in which the fiber bundle is filled in a freezing container and is immersed in water, wherein the freezing container includes the ice container A method of freezing a fiber bundle for producing ultrashort fibers, wherein the water on the water surface is heated from above to heat the water surface portion to prevent freezing of the water surface portion while freezing the water filled in the freezing container.   The method for freezing a fiber bundle for producing ultrashort fibers according to claim 1, wherein the air exhaust on the water surface is performed under a weak negative pressure of 30 to 650 torr.   The method for freezing a fiber bundle for producing ultrashort fibers according to claim 1 or 2, wherein the freezing vibration is applied to the freezing container for freezing.   The method for freezing a fiber bundle for producing ultrashort fibers according to any one of claims 1 to 3, wherein water to be subjected to the freezing treatment is deaerated in advance. When producing a very short fiber by freezing a fiber bundle in which a large number of single fiber groups are aligned and bundled so as to be parallel to each other in the longitudinal direction of the fiber, and cutting the frozen fiber bundle into a flake shape, An icing container for allowing the fiber bundle to stand and filling water for immersing the fiber bundle, a lid member provided at the top of the icing container and maintaining the inside of the container to be airtight, and water charged in the icing container A fiber bundle for producing ultrashort fibers comprising at least a heating device for heating an upper portion of a container including a water surface portion so as not to freeze, a refrigeration device for cooling the frozen container, and an exhaust device attached to the lid member Freezing processing equipment.   The icing treatment apparatus for fiber bundles for producing ultrashort fibers according to claim 5, further comprising a gas-liquid separator between the lid member and the exhaust device.   The apparatus for freezing a fiber bundle for producing ultrashort fibers according to claim 5 or 6, further comprising a fine vibration generator for applying fine vibration to the freezing container.

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