JPH0749608B2 - Method and device for dehumidifying continuous fiber bundle and low-temperature drafting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for producing a bundle of continuous fibers, for example, a bundle of discontinuous fibers which is an intermediate product for producing a spun yarn from a tow or multifilament. For more details,
A dehumidifying tank, a cooling tank equipped with a refrigerator, and a drafting machine are sequentially arranged,
Moisture contained in the bundle of continuous fibers running in the dehumidification tank,
Dehumidifying the moisture of the associated air accompanying the continuous fibers, and immediately after that, the continuous fiber bundles are brought into contact with a medium of -5 ° C or lower in a cooling tank immediately connected to each other and deep-cooled immediately. The present invention relates to a method and an apparatus for producing a bundle of discontinuous fibers by applying a drawing force and / or a shearing force to the bundle of continuous fibers to cut each single fiber constituting the fiber bundle.

<Prior Art> The freeze check method is disclosed in JP-A-58-60021, JP-A-58-60022, and JP-A-58-60022.
As disclosed in the specification of 58-203107, in tow spinning, when producing a bundle of discontinuous fibers from a bundle of continuous fibers, the fibers are drafted at a low temperature.

When this freezing and drafting method is used, the acrylic synthetic fiber shown in FIG.
Wei (Product name Kashmiron ) 3d, 20 bundles at each temperature
As is clear from the tension-elongation diagram,
The amount of plastic deformation is extremely small, and
Since it can be cut, the strength and elongation of the monofilament after stretching is maintained,
Since there is little residual strain, it is possible to use a single 100 (° C) boil.
Discontinuous fibers having single fiber groups with extremely low fiber shrinkage
You can get a bunch of. And of the continuous fiber to supply
If each single fiber forming the bundle has a crimp,
To obtain a bundle of discontinuous fibers in which this crimp is maintained even after drafting.
You can In this way, the discontinuous fibers obtained by freeze drafting
The physical properties of single fibers in a bundle of
Maintains physical properties. In addition, it is possible to
Discontinuous fiber with excellent parallelism that inherits the parallelism of c
You can get a bunch of.

As described above, the freezing and drafting method has little shrinkage even after drafting, has crimps, and can maintain the physical properties of the raw cotton in terms of strength and elongation, and it is possible to obtain an ideal sliver with excellent parallelism. Since it is obtained in the process, the process can be remarkably shortened as compared with the conventional spinning process. In addition, there is little fly in the spinning process such as nep and slab, and the quality can be improved. Furthermore, when it is checked at low temperature, it transitions from ductile fracture to brittle fracture, and the cut surface of the single fiber becomes slanted and tapered. As described above, the freezing and drafting method is a very effective and distinctive drafting method.

However, in the freezing and drafting method, a bundle of continuous fibers is run in a cooling tank and deep-chilled sufficiently, and then immediately the draft is cut, but the continuous fibers that have been exposed to the outside air containing a lot of water are After passing the bundle directly into the cooling tank and deep-chilling sufficiently, when performing drafting with a continuous drafting machine, the moisture in the outside air is solidified at a low temperature, at the time of drafting and immediately after drafting. The migration draft of each monofilament becomes defective, resulting in partial group breakage and uneven stretch. As a result, there is a drawback that the quality is deteriorated, for example, the U% of the discontinuous fiber bundle is deteriorated, the staple diagram is deteriorated, and the fly is increased.

Fig. 2 shows the relationship between the dew point temperature of air and the water content per 1 [Nm ³ ] in the standard state from the saturated vapor pressure table. For example,
When the atmospheric temperature is 25 (° C), it becomes saturated with about 26 (g / Nm ³ ) of steam, and there is steam corresponding to about 17 (g / Nm ³ ) at a relative humidity of 65 (%). The saturated vapor pressure at low and extremely low temperatures is extremely low, and when this outside air is cooled to, for example, -80 (° C) or lower, most of the steam equivalent to about 17 (g / Nm ³ ) solidifies.

On the other hand, the fiber itself also contains water inside and on its surface, and the water content varies depending on the type of fiber and the external environment thereof. In some cases, a large amount of water is locally contained during transportation, and these water also have various adverse effects on freeze-thaw clearance.

Moreover, these waters have a bad influence not only on the freezing and drafting property but also on the cooling tank. When such water enters the cooling tank, frost is formed on each part in the cooling tank. In order to deeply cool the bundle of continuous fibers in the cooling tank, it is necessary to increase the residence distance, and when a rotating roller is provided, defective rotation occurs due to dew condensation. The rigidity of the fiber increases at low temperatures, and excessive rubbing damages the fiber surface. In addition, frost is formed on the evaporator surface of the refrigerator, heat exchange is reduced, and the refrigerating capacity is reduced.

The inventors of the present invention, when performing the freezing and drafting method, dehumidify the water intruding by running the bundle of continuous fibers before cooling the bundle of continuous fibers from the above-mentioned surface, and in an extremely low state. As a result of various investigations, the present invention has been achieved, paying attention to the fact that it is necessary to send it into the cooling tank.

<Object of the Invention> The present invention is to dehumidify the water contained in a bundle of continuous fibers to obtain a U of a bundle of discontinuous fibers coming from a check unevenness at the time of check cutting.
%, It is possible to provide a low-temperature drafting method and apparatus capable of producing a bundle of discontinuous fibers with excellent quality by eliminating deterioration of quality, deterioration of staple diagram, and stable production for a long time. To aim.

<Structure of the Invention> An object of the present invention is to produce a bundle of discontinuous fibers by applying a stretching force and / or a shearing force to the bundle of continuous fibers to cut off each single fiber constituting the bundle of continuous fibers. In the method described above, the moisture contained in the running continuous fiber bundle and the moisture of the accompanying air accompanying the continuous fiber are removed to dehumidify, and the continuous fiber bundle is continuously reduced to −5.
It is achieved by a method for producing a bundle of discontinuous fibers, which comprises contacting with a medium at a temperature of not higher than 0 ° C., deep cooling, and then immediately breaking.

A more preferable apparatus for carrying out the method of the present invention is to continuously produce a bundle of discontinuous fibers from a bundle of continuous fibers in which a dehumidifying tank, a cooling tank equipped with a refrigerator and a drafting machine are sequentially connected. It is a low-temperature shut-off device, the dehumidifying tank is switchably connected to two or more sets of cooling and dehumidifying devices having an evaporator connected to a refrigerator, and the air contained in a bundle of continuous fibers is dew point of -5 ° C or less. The cooling tank is equipped with an evaporator connected to the refrigerator in the atmosphere circulation passage in the tank, a heater that also controls temperature and defrosts inside the cooling tank, and an air supply fan. It is a tank capable of deep-cooling a bundle of fibers to -5 ° C or lower, and a drafting machine is a machine capable of drafting a bundle of continuous fibers at a low temperature.

Dehumidification performed in the present invention is performed by passing the bundle of continuous fibers through a dehumidification tank having an inlet and an outlet for the bundle of continuous fibers. As a dehumidifying method, a method of heating and drying a bundle of continuous fibers, a method of dehumidifying by cooling, a method of running between a chemical hygroscopic agent such as silica gel or a physical adsorbent,
A method of running between dry gases can be used. Further, a method of drawing a slight vacuum may be used together.

The dehumidifying time varies depending on the type of fiber, the feeding method and the dehumidifying method, but is generally preferably about 1 to 15 minutes.

The method of contacting the bundle of continuous fibers with the dehumidifying medium is not particularly limited, but may be in contact with the medium surface or may pass through a gas atmosphere.

In addition, the dehumidification tank is divided into two or more chambers, the first chamber is heated with an infrared heater or the like to dehumidify, and then the second chamber is run in an adsorbent or cooled to dehumidify in multiple stages. ,
It is desirable to perform efficient dehumidification by combining various dehumidification methods.

In this way, the moisture in the bundle of continuous fibers is dehumidified to the moisture having a dew point temperature equal to or lower than the cooling temperature of the cooling tank. When the cooling temperature is extremely low, it is difficult to obtain water having a dew point temperature below that temperature. However, as shown in FIG.
The water content at the dew point temperature (° C) is extremely small, and does not change much compared to the water content in the air having a low dew point temperature. Therefore, the lower the moisture content of the bundle of continuous fibers to be supplied, the better, but the moisture content is preferably dehumidified to a moisture content of -40 (° C) or less. This makes it possible to eliminate a partial checkout unevenness caused by the solidification of water, and to manufacture a bundle of discontinuous fibers having a good sliver U% and a staple diagram. In addition to this, the dehumidification tank dehumidifies the moisture of the accompanying air accompanying the traveling of the bundle of continuous fibers, prevents the moisture from entering the cooling tank, and prevents dew condensation, thereby preventing the rotation failure of the rotating roller. It is possible to prevent the fiber from being damaged and the refrigerating capacity from being deteriorated due to frost on the evaporator. Due to these actions and effects, it is possible to carry out the freezing and drafting continuously and stably for a long time, and to further enhance the effects.

However, in general, fibers generate heat when stretched and cut.
This is because when work is added to the fiber, this work is stored as potential energy when elastically deformed, whereas when further deformation begins and plastic deformation begins, this work is converted into heat energy and released. . In Figure 1
The plastic deformation region at 20 (° C) is the area of a ', a, b, b', and this work determines the amount of heat generation. When the cutting temperature decreases, this area increases once and then decreases to -100
At (° C), most of the heat is cut in the elastic region, and the amount of heat generated is significantly reduced. FIG. 3 shows the relationship between the plastic deformation region and the cutting temperature. Here, I is a fiber bundle shown in FIG. 1, and II is a low elongation type fiber also under the trade name of Kashimilon, but it is cut in a certain degree or less, and it is in the elastic region or a region in the vicinity thereof. If there is, the heat generated by the draft will almost disappear.

In addition, when the checkout is performed in two or more stages, it is shown in FIG.
In the case of fibers such as II, the temperature of the fibers does not rise to a high level when the material is stretched in the second step, and the shrinkage after the opening is low, but in the case of fibers such as I, heat is generated in the first step and then the second step Since the fiber temperature is high when the fiber is stretched again, the plastic fiber is deformed to increase the shrinkage rate of the single fiber, and a spun yarn with low shrinkage cannot be obtained. Therefore, in order to realize the advantage of freezing and drafting, that is, to obtain a spun yarn with low shrinkage, it is necessary to take away swiftly cutting heat quickly if it occurs. Alternatively, it is necessary to cool the bundle of discontinuous fibers that have generated heat again.

Therefore, when carrying out the present invention, in a drafting machine comprising two or more pairs of nip rolls, it is preferable to provide a low temperature drafting bath, a cooling body or a recooling bath equipped with a cooling means between arbitrary nip rolls. When the drafting heat is generated with the drafting, the low temperature drafting tank or the cooling body absorbs heat to prevent the temperature rise of the fiber bundle, or the drafting of the discontinuous fibers heated in the first stage to raise the temperature. The bundle is cooled again in the recooling tank and rechecked.

The cold draft according to the present invention is carried out by passing the bundle of continuous fibers through a cooling tank having an inlet and an outlet for the bundle of continuous fibers. Liquid nitrogen, liquid helium,
Dry ice, a low temperature gas (usually air) obtained by a refrigerator, a low temperature liquid, a solid or the like may be any as long as it can obtain a low temperature of -5 (° C) or lower, preferably -20 (° C) or lower, Industrially, it is most preferable to use a refrigerator that is cost-effective and can be operated anywhere. Due to these things, the present invention is premised on using a refrigerator for cooling, whether the evaporator of the refrigerator is built-in, or
Pass a bundle of continuous fibers through a bundle of continuous fibers in a cooling tank that is connected to a chamber containing an evaporator by a duct, or apply cold air,
Cooling is performed by contacting an object exposed to low temperature.
In addition, the inlet and outlet of the bundle of continuous fibers are provided with one or more pairs of nip rolls or slits, etc., so that the cool air in the cooling tank does not leak and the outside air does not enter, and the temperature in the tank is kept constant. keep.

The bundles of continuous fibers used in the method and apparatus according to the present invention include filaments, tows, etc. of total denier of 30 (d) to 2 million (d) mainly composed of 0.1-100 (d) of single fiber denier. Fiber bundles are used, and as the fibers, there are synthetic fibers such as polyacrylic, polyester and polyamide, and regenerated fibers such as rayon and cupra.

EXAMPLES The present invention will now be described in detail below with reference to the accompanying drawings showing various examples of an apparatus used for carrying out the method for producing a bundle of discontinuous fibers according to the present invention.

FIG. 4 is an apparatus diagram showing an example of an apparatus for producing the above-mentioned bundle of discontinuous fibers, that is, a low temperature drafting apparatus. In FIG. 4, 1 is single yarn denier 6 (d), total denier
It is a tow-shaped continuous fiber bundle having crimps of 600,000 denier acrylic synthetic fibers (trade name: Cashimiron). 1
The tow 1 is chopped and receded between the pair of nip rollers 2 and 2, the pair of nip rollers 3 and 3, and the pair of nip rollers 4 and 4 to form a sliver 61 which is a bundle of discontinuous fibers. A cooling tank A for cooling the tow 1 is connected to the front of the checker B. Cooling tank A has a pair of feed rollers with a tow 1 feed port
The outlet is closed by the pair of nip rollers 2, 2 of the drafting machine B. The cooling tank A has an outer periphery covered with a heat insulating material 6 and is kept in a low temperature atmosphere to continuously cool the tow 1. A dehumidifying tank C is continuously provided in front of the cooling tank A. The dehumidifying tank C is provided with a pair of nip rollers 7, 7 at the outlet of the tow 1, and the inlet 8 of the tow 1 has a slit shape. An infrared heater 26 is incorporated in the dehumidifying tank C to heat the moisture contained in the tow while the tow 1 passes therethrough, and dehumidify it by exhausting it as water vapor from the exhaust port 27. Further, in this apparatus, a low temperature drafting tank D is provided between the nip rollers 2, 2 and 3, 3 of the drafting machine B.
The tank D is covered with a heat insulating material 6 and is closed by the respective nip rollers 2, 2 and 3, 3 of the checker B. This tank D actively cools the raw cotton which has a particularly high heat generation due to the drafting heat so that the drafting heat can be quickly removed. Toe 1 is roller 2,2,3,3 and 4,
The sliver 61 is cut by being subjected to a stretching force and / or a shearing force between 4 respectively. Then, the sliver 61 passes through the converging roller 9 and is coiled and stored in the can 10 by the coiler F. In addition, a refrigerator unit for supplying cold heat required for freezing and drafting is incorporated in E.

FIG. 5 is a detailed view of the cooling tank A, (a) is a vertical sectional view from the front, and (b) is a vertical sectional view from the side. Tow 1
Is meandering by a plurality of rotary rollers 11 with a collar in the tank,
A pair of feeding rollers 5,5 and a pair of nip rollers for the drafting machine
Transported by 2 and 2. The inlet and outlet of the cooling tank A are closed by respective nip rollers 5, 5 and 2, 2.
In the atmosphere circulation passage 12 in the tank, an evaporator 13 connected to a refrigerator, a heater 14 which serves as a temperature control and a defroster in the cooling tank A
Further, the air supply fan 15 is built in, and the low temperature atmosphere cooled by the evaporator 13 is supplied from the circulation passage 12 to the air supply fan 1
5, Flowed by the straightening plate 20, and fed into the tank. 16 is a fan drive motor. The atmosphere in the tank flowing in the direction of the arrow (a) hits the tow 1 and is cooled, and the suction port 17 in the tank is cooled.
It is sucked in more and circulates in the direction of arrow (b). The suction port 17 is provided with a filter 18 so that fried fibers, dust and the like do not get to the evaporator.

FIG. 6 is a detailed view of the dehumidifying tank C, where (a) is a vertical sectional view from the front and (b) is a vertical sectional view from the side.

The tow 1 meanders in the dehumidifying tank C by means of a rotary roller 23 with a collar, and a pair of nip rollers 7 provided at the outlet of the dehumidifying tank C.
It is conveyed in the dehumidification tank C by 7. The inlet 8 of the dehumidifying tank has a slit shape. A heating heater 26 for infrared rays or the like is incorporated in the dehumidification tank C, and the tow 1 running in the tank 1
Also, the moisture in the outside air accompanying the traveling of the tow is heated and discharged as steam from the exhaust port 27 for dehumidification. Exhaust is performed by the exhaust fan 28. Reference numeral 21 indicates a circulating fan in the tank, and arrow 22 indicates the wind direction.

For dehumidification, the dew point temperature of the atmosphere between the nip rollers 7,7 and 5,5 is −
Control so that the temperature does not exceed 5 ° C.

As long as the dehumidifying tank can efficiently dehumidify, dehumidification by cooling may be performed as shown in FIG. Where (a)
Is a vertical sectional view from the front, (b) is a line VII (b) of (a)
-VII (b) is a side view. The dehumidifying tank G is provided with a pair of nip rollers 30, 30 and 31, 31 at the inlet and outlet of the tow 1 to close the inside of the tank. The dehumidifying tank G is connected to the cooling and dehumidifying devices H and I, and by cooling the tow 1 with the cooling and dehumidifying devices H and I, dehumidifying water that enters along with the traveling of the tow 1. The inside of the cooling and dehumidifying devices H and I is an evaporator 32 connected to a refrigerator, and a heater 3 that also functions as a temperature control and defroster in the cooling and dehumidifying tank 3
3 and a suction fan 34 for sucking in / invading water is built in, and dehumidifies the water in the tow 1 and invading air by frosting the invading water on the evaporator 32. When dehumidifying by this method, the dehumidifying ability of the evaporator 32 is reduced when it is operated for a long time. Therefore, in the low-temperature drafting device for continuous fiber bundles according to the present invention, two sets of cooling and dehumidifying devices, that is, H and I are provided, and
Switching operation is performed for each set. The switching is performed by rotating the dehumidification tank G by 180 °. In FIG. 7, the dehumidifying inlets / outlets 37, 38 of the dehumidifying tank G and the inlet / outlet ports 35, 36 of the cooling / dehumidifying device H are connected. The switching is performed by rotating the dehumidification tank G by 180 ° so that the dehumidification inlets / outlets 37, 38 are aligned with the inlets / outlets 35, 36 of the cooling / dehumidifying device I. Dehumidification entrance / exit 37,38 during this rotation
A blocking plate 39 is provided so as not to contact the outside air. The rotation is performed by transmitting drive to a gear 40 provided in the dehumidifying tank G. At this time, the cooling and dehumidifying devices H and I and the entrance and exit rollers 30 and 3
1, the blocking plate 39 is stationary. After the switching, the cooling / dehumidifying tank I starts dehumidifying, and at the same time, the cooling / dehumidifying tank H is defrosted. Defrosting is performed by the heater 33, but at this time, the valve 41 is opened and warm air is circulated. Further, the exhaust port 42 is opened so that the steam can be exhausted from the cooling / dehumidifying device H. The shaded area in the drawing indicates the heat insulating material.

FIG. 8 shows a dehumidifying method and apparatus in which the dehumidifying tank C shown in FIG. 6 and the dehumidifying tank G shown in FIG. 7 are combined to perform more efficient dehumidification, followed by a cooling tank. A
Immediately after the tow 1 is continuously deep-chilled, the sliver 61 is drafted by the drafting machine B.

FIG. 9 is a detailed view of the low temperature draft tank, in which a cooler 51 and an air-blowing fan 52 in which a refrigerant circulates inside the tank are provided below a cooling plate 50 in the tank, and circulates while cooling the atmosphere in the tank. Then, the linear velocity of the nip rollers 3, 3 is made higher than the linear velocity of the nip rollers 2, 2 and an appropriate load is applied by hydraulic pressure to make the fiber bundle 2
The pair of rollers is spun off and spun without a bundle of discontinuous fibers, here a sliver 61. The bath temperature is nip roller 2,2
And near the nip rollers 3,3, behind the cooler 51, etc.
The temperature is detected by a temperature detecting end such as a platinum resistor or a thermocouple provided at an arbitrary position and automatically controlled.

Generally, when the tow is chopped off, flies are generated, but when the choke area is closed, this fly accumulates and interferes with continuous operation or floats and enters the sliver, which deteriorates the quality. D is convenient for removal,
A filter 53 is provided in the circulation passage at the bottom of the tank so that the fries can be collected. Further, brushes 54 are provided above and below the nip rollers 2 and 2 so as to prevent the winding of the single fiber. In order to prevent contact between the atmosphere inside the container that has become low temperature and the outside air, the side surfaces of the two pairs of rollers and the inner wall of the tank are rubbed together, and an appropriate load is applied between the two pairs of upper and lower rollers to nip the inside of the tank. Prevent contact between atmosphere and outside air. Next, in order to prepare the staple diagram, a stretching force is applied between the nip rollers 3, 3 and 4, 4 to perform re-challing. Here, it is desirable to cover the nip rollers 3, 3 and 4, 4 with a heat insulating material 6 so that the fiber bundle is not heated by the outside air. It is also possible to actively cool. Laura 2,
2 and 3, 3, 4, and 4 are preferably rubber and resin excellent in low temperature resistance and mechanical properties.

Cooling plates 50, 50 provided above and below the fiber bundle in the process of drafting are rounded at both ends so that a metal plate with excellent heat conduction such as copper or aluminum does not hinder the progress of the fiber bundle. It has a finished contact surface. The lower cooling plate 50 is fixed to the lower part of the tank with a bar or the like, and the upper cooling plate 50 is provided with holes to pass through the bar. Alternatively, a load may be applied by a spring to positively contact the fiber bundle to the extent that it does not hinder the running of the fiber bundle. The heat generated by the draft can be detected by a temperature detection end provided at any position of the cooling plates 50, 50, and the temperature in the tank may be adjusted by this temperature. When the heat of drafting is generated, the heated cooling plates 50, 50 are cooled by the low-temperature atmosphere in the tank, and heat is quickly released from the fiber bundle in the process of drafting by contacting the metal having excellent heat transfer. It can be robbed. Reference numeral 6 indicates a heat insulating material.

The evaporation temperature in the refrigerator unit E is -120.
It has a built-in ternary refrigerator capable of obtaining (° C.) and is connected to the evaporator 13 in the cooling tank A.

The evaporators 51 and 32 are also connected to their own refrigerators.

Hereinafter, specific examples of low-temperature drafting using the low-temperature drafting device according to the present invention, and performance of a bundle of discontinuous fibers obtained by the specific examples will be shown in comparison with a conventional example.

Specific Example 1 A tow having a crimp of 600,000 d composed of 6 denier (d) of acrylic synthetic fiber was spun under the following conditions by the apparatus shown in FIG. Next, the above-mentioned tow was spun on the apparatus of FIG. 4 without dehumidification, and the results were compared.

Dehumidification conditions Tank temperature 50 (℃) Cooling tank Tank temperature -16 (℃) Nip roll 2,2 speed 8 (m / min) Shutter ratio (between rollers 2 and 3) 3.5 (times) (between 3 and 4) ) 1.5 (times) Low temperature drafting tank No cooling Grip length of rollers 2 to 250 (mm) Grip length of rollers 3 to 140 (mm) The results are shown in Table 1.

As is clear from Table 1, dehumidification is performed at a dew point temperature of -32 (° C).
Compared to the case without dehumidification,
Even in the sliver in which contraction did not appear after 15 minutes,
In the spinning, partial breakage was eliminated, good drafting property was obtained, and sliver U% was improved. Further, in the staple diagram, too long fiber length and short fiber content were reduced, which was greatly improved.

Next, a comparison was made for the case of long-time operation.

As for the spinning, the one without a dehumidification tank still has many partial breaks. In addition, the degree of occurrence of large staggering spots and flies increased, resulting in a serpentine sliver. The shrinkage rate of the monofilament in the sliver also increases with time, the crimp of the spun sliver also grows, and the number of areas without shiny crimp increases. After 3 hours, it became a slippery sliver with no crimp, and the sliver was not tied at all. On the other hand, in the case of the method according to the present invention, the drafting property is good even after 3 hours, the shrinkage rate of the single fiber is as low as 4.3%, and the conjugation having the crimp of the original tow is obtained. A highly active and bulky sliver was obtained.

By providing a dehumidifying tank in this way, there is little shrinkage even after drafting, there is crimping, parallelism and staple diagram are good, and ideal sliver that approaches a random sliver is stable for a long time. It has become possible to manufacture.

Specific Example 2 A tow having a crimp of 560,000 d composed of 3 denier (d) of acrylic synthetic fiber was spun in the apparatus shown in FIG. 4 under the following conditions. Next, the above-mentioned tow was spun by the apparatus shown in FIG. 4 without cooling the low temperature draft tank, and the results were compared.

Dehumidification conditions Tank temperature 50 (° C) Cooling tank Tank temperature −100 (° C) Low temperature drafting bath internal temperature −90 (° C) Nip roll 2,2 speed 8 (m / min) Draft drafting ratio (between rollers 2 and 3) ) 4.35 (times) (between 3 and 4) 1.5 (times) Gripping length of rollers 2 to 250 (mm) Gripping length of rollers 3 to 140 (mm) The results are shown in Table 2.

As a result, in Example 1, good drafting property was obtained without cooling the inside of the low-temperature drafting tank, and the advantage of freezing drafting could be sufficiently obtained. As shown in Table 2, in the case of raw cotton having a high cutting energy, heat is generated by the drafting between the rollers 2 and 3, so that the fiber temperature rises and the drafting property at the time of the re-launching is poor, resulting in partial breakage. Drafts, group breaks, etc. occur, and the serpentine sliver U% becomes bad.

In addition, the shrinkage rate of the single fiber after boiling becomes high, so that not only a spun yarn having a low shrinkage rate cannot be obtained, but also the crimps after the draft cutting disappear. Then, there is a problem that the staple diagram also becomes worse. On the other hand, the temperature inside the low-temperature draft tank is -90 ° C.
The heat generated by the drafting is removed by cooling to 1. On the other hand, it becomes possible to prevent the heating by the roller 3, and it is possible to perform the freeze drafting stably for a long time.

Concrete Example 3 A tow having a crimp of 600,000 d composed of 6 denier (d) of acrylic synthetic fiber was used in the apparatus shown in FIG. 8 by using only the cooling and dehumidifying tank shown in FIG. It was spun under the conditions. Next, the above tow was spun by the apparatus shown in FIG. 8 without dehumidification, and the results were compared.

Moisture content of tow 25% Dehumidification condition Cooling dehumidification tank temperature -30 (℃) Cooling dehumidifier H / I switching condition 1 hour Cooling condition Tank temperature -60 (℃) Nip roll 2,2 Speed 8 (m / min) Draw-off ratio (between rollers 2 and 3) 2.35 (times) (〃 between 3 and 4) 1.5 (times) Low-temperature draw-off tank No cooling Grip length of rollers 2 and 3 250 (mm) Grip length of rollers 3 and 140 140 (Mm) The results are shown in Table 3.

As a result, by performing dehumidification under the above conditions, compared with the case where dehumidification is not performed, in both cases, even in the sliver in which shrinkage did not occur after 15 minutes, the spinning did not cause partial breakage and good spinning was achieved. Cuttability was obtained and the sliver U% was improved. The staple diagram was also good.

As for long-term operability, there are still many partial breaks without a dehumidifying tank. In addition, the occurrence of flies and check-off spots increased, resulting in a sliver-like sliver. The boil shrinkage rate of the monofilament in the sliver increases with time, and the crimp of the monofilament of the spun sliver also expands, increasing the number of areas without shiny shiny crimp. And it becomes a smooth sliver without crimps, and it is less bulky,
There was no sliver hugability at all.

On the other hand, in the method of the present invention, the stretch-off property was good and the boiling shrinkage rate of the single fiber remained low even after a long time. In addition, a sliver having a high clinging property and having a crimp of the original tow was obtained. By providing a dehumidifying tank in this way, there is little shrinkage even after drafting, there are crimps, and parallelism, unevenness, and staple diagrams are as good as possible, and a sliver that is close to a random sliver is stably manufactured for a long time. It has become possible.

In this way, by performing dehumidification for cooling, it is possible to dehumidify the moisture of the associated air. In this case, it is preferable to raise the wind speed of the fan 34 to such an extent that the tow is not disturbed. In this specific example, it was performed at 10 m / sec. As a result, the associated air is quickly sucked, and the evaporator of the cooling / dehumidifying device is defrosted with moisture.

In particular, in the case of a tow with a moisture content of more than 10%, it is preferable to not only simply cool and dehumidify, but also to actively dry the tow moisture and then cool and dehumidify it. After dehumidifying, next, efficient dehumidification can be performed by frosting the moisture of the evaporator of the cooling dehumidifying device in a state where the temperature is high and a large amount of moisture is contained in the atmosphere.

<Effects of the Invention> Since the present invention is configured as described above, the following effects can be obtained by using the method or apparatus of the present invention.

(1) There is no partial breakage during drafting, there is little shrinkage even after drafting, it has the original crimp of the tow, and it is a random sliver with good parallelism, unevenness, and staple diagram. It is possible to manufacture an approaching sliver in one step and stably for a long time.

(2) By rapidly removing the heat of drafting in the low temperature drafting tank, it becomes possible to redraft raw cotton with high heat of drafting, and it is possible to obtain an excellent sliver as described above.

(3) In addition, there is no frost in the cooling tank, there is no scorching due to the condensation of the rotating roller, there is no fiber damage, and the staple diagram, cut-off, fly, and physical properties are improved. Also, the reduction of the refrigerating capacity has disappeared.

(4) The cooling tank sealing structure can be simplified.

[Brief description of drawings]

 Fig. 1 shows an acrylic synthetic fiber (trade name: Kashimilon) ) 3
d, a graph showing the tension-elongation diagram of 20 bundles at each temperature
It is. Fig. 2 shows the saturation evaporation table from the dew point of air and standard conditions.
1 Ncm³It is a graph which shows the relationship of the amount of water per hit. FIG. 3 shows the plastic obtained from the tension-elongation diagram shown in FIG.
It is a graph showing the relationship between the elastic deformation region and the cutting temperature.
(I) is the fiber bundle shown in FIG. 1, and (II) is the same.
Jiku Acrylic Synthetic Fiber (Product Name: Cashimiron ) Low
Elongation type fiber bundle. FIG. 4 shows a method for producing a bundle of discontinuous fibers according to the present invention.
An example of a device for carrying out, that is, a low temperature drafting device
It is a schematic front view. FIG. 5 is a drawing showing the details of the cooling tank, and (a) is the front view.
Is a vertical cross-sectional view from the side, and FIG. FIG. 6 is a drawing showing an embodiment of a heating type dehumidifying tank,
(A) is a vertical cross-sectional view from the front, (b) is a vertical section from the side
It is a side view. FIG. 7 is a cooling type used in the low temperature drafting device according to the present invention.
It is drawing which shows one Example of a dehumidification tank, (a) is from the front
2B is a vertical cross-sectional view from the side. FIG. 8 shows the heating type dehumidifying tank shown in FIG. 6 and FIG.
An example of low temperature drafting device using combined cooling type dehumidification tank.
It is a schematic front view which shows. FIG. 9 is a vertical cross-sectional view showing details of the low temperature draft tank. A ... Cooling tank, B ... Checking machine, C ... Dehumidifying structure, D ... Low
Hot and cold shut-off tank, HI ... Cooling dehumidifier, 1 ... Tow, 2, 3,
7 …… Nip roller, 5 …… Feed roller, 6 …… Heat insulation
Material, 8 …… Slit, 61 …… Sliver.

Claims (4)

[Claims] 1. A method for producing a bundle of discontinuous fibers by applying a stretching force and / or a shearing force to the bundle of continuous fibers to cut off each single fiber constituting the bundle of continuous fibers to produce a bundle of discontinuous fibers. Characterized by dehumidifying the moisture contained in the bundle of continuous fibers and the moisture in the air accompanying the continuous fibers to dehumidify it, and then continuously contacting the bundle of continuous fibers with a medium at -5 ° C or lower to deep-chill and then immediately drafting. And a method for producing a bundle of discontinuous fibers. 2. A bundle of continuous fibers chilled to -5.degree. C. or lower is deep-cooled, and then immediately chilled while cooling to -5.degree. The method for producing a bundle of discontinuous fibers according to claim 1, wherein the bundle is cooled and cooled again. 3. A low-temperature drafting device for continuously producing a bundle of discontinuous fibers from a bundle of continuous fibers in which a dehumidifying tank, a cooling tank equipped with a refrigerator, and a drafting machine are successively arranged, the dehumidifying tank Is -5 for the air contained in the bundle of continuous fibers, which is switchably connected to two or more sets of cooling / dehumidifying devices with built-in evaporators connected to the refrigerator.
It is a tank that can dehumidify to a dew point of ℃ or below, and the cooling tank is equipped with an evaporator connected to the refrigerator in the atmosphere circulation passage in the tank, a heater that also serves as temperature control and defrost in the cooling tank, and an air supply fan. It is a tank that has a bundle of continuous fibers that can be deep-cooled to -5 ° C or less, and the drafting machine is a machine that can draft the bundle of continuous fibers at a low temperature. apparatus. 4. A low-temperature drafting tank provided with at least two pairs of nip rolls and a cooling means provided with a cooling means between arbitrary nip rolls, wherein each of the nip rolls cold drafts a continuous fiber bundle. The low-temperature drafting device according to claim 3, wherein the inlet and the outlet to the tank are closed.