WO2004044282A1

WO2004044282A1 - Method and device for melt spinning and cooling a plurality of synthetic filaments

Info

Publication number: WO2004044282A1
Application number: PCT/EP2003/011807
Authority: WO
Inventors: Horst Kropat
Original assignee: Saurer Gmbh & Co. Kg
Priority date: 2002-11-09
Filing date: 2003-10-24
Publication date: 2004-05-27
Also published as: CN1711375A; JP2006505705A; EP1560952A1; DE50310587D1; EP1560952B1

Abstract

The invention relates to a method and a device for melt spinning and cooling a plurality of synthetic filaments. According to said method, the filaments are first extruded in an annular configuration by means of a spinneret (1) and are then guided along a blowing tube (12) and cooled by a radial air stream emerging from the jacket of the blowing tube. The invention is characterised in that the filaments are pre-cooled for setting purposes prior to being cooled by the jacket air stream, by means of an additional pre-cooling air stream (7), which is generated by a coolant (6) that is located between the spinneret (1) and the blowing tube (12).

Description

Process and apparatus for melt spinning and cooling a variety of synthetic filaments

The invention relates to a method for melt spinning and cooling a plurality of synthetic filaments according to the preamble of claim 1 and to an apparatus for carrying out the method according to the preamble of claim 6.

A generic method and a generic device are known for example from DE 36 29 731 AI.

In the manufacture of staple fibers, the fibers are previously extruded from a polymer melt using a spinneret with a large number of nozzle bores as strand-like filaments. Depending on the hole throughputs and the withdrawal speeds from the spinneret, a distinction is made between the so-called short spinning processes and the long spinning processes. In the short spinning processes, low take-off speeds and low hole throughputs are set, so that cooling of the freshly extruded filament strands is possible within a short distance. In such processes, however, spinnerets are used which have a very large number of nozzle bores, so that a relatively dense filament curtain is produced and has to be cooled. For this purpose, cooling devices are used, for example, as is known from US Pat. No. 5,178,814. A very short length of cooling air flow is generated below the spinneret and penetrates the filament curtain radially from the inside to the outside.

In the so-called long spinning processes, on the other hand, a much larger throughput is achieved through the spinneret and accordingly significantly higher take-off speeds. In order to optimally cool the freshly extruded filaments, a long and even blowing section is required. The so-called blow candles, which have a form an even blowing section on its jacket of a radially emerging jacket air flow. Such a method and such a device are known from DE 36 29 731 AI, from which the invention is based.

In the known method and the known device, the filaments are extruded through ring-shaped nozzle bores in the spinneret. The blow candle is arranged below the spinneret. The blow candle has a porous sheath, which consists, for example, of a sintered material, so that the cooling air introduced into the inside of the blow candle by an air supply radially emerges from the sheath of the blow candle and cools the filament strands that are guided past the blow candle as a sheathed air stream. In the known device, the blow candle has a closable annular gap at the free end, which is opened for pivoting and moving the blow candle, so that the filament strands cannot stick to the blow candle while the blow candle is being moved into an operating position. As soon as the blow candle has reached its operating position below the spinneret, the annular gap is closed. The filaments are cooled exclusively by the jacket air flow.

In the known method and the known device, it has now been found that, in particular when melt spinning and cooling filaments with fine titers, breaks often occur in the case of external filaments. Since the occupancy of the nozzle bores in the spinneret, and thus that of the extruded filaments, is larger in the case of fine titers than in the case of thick titers, the jacket air flow of the blow candle causes inadequate cooling of all the filaments.

The problem could not be solved by setting a blow profile on the blow candle, as is known for example from DE 37 08 168 AI. The invention has for its object to develop a method and an apparatus of the type mentioned in such a way that a plurality of extruded filaments with relatively fine titers, which are guided in an annular arrangement, can be cooled uniformly.

This object is achieved according to the invention by a method with the features according to claim 1 and by a device with the features according to claim 6.

Advantageous developments of the invention are defined by the features and combinations of features of the respective subclaims.

The invention has the advantage that cooling of the filaments begins immediately after the filaments emerge from the spinneret. For this purpose, an additional coolant between the spinneret and the blow candle generates a pre-cooling air flow which is directed towards the filaments for pre-cooling. This results in greater flexibility in cooling the filaments. The intensive pre-cooling of the filaments showed the possibility, particularly in the production of staple fibers, to produce particularly fine titers.

The effect could also be improved in that, in the method according to the invention, the pre-cooling air stream and the jacket air stream hit the filaments in the same direction, the flow rate of the pre-cooling air stream being higher than the flow rate of the jacket air stream. This enabled the filament curtain to expand evenly on the one hand, and on the other hand, the intensive pre-cooling air flow led to uniform and continuous pre-cooling of all filaments within the filament curtain. The subsequent further cooling of the filaments by the jacket air flow along the blow candle enables in particular a uniform solidification of the filaments even at higher take-off speeds. In order to obtain a uniform and intensive penetration of the filament curtain for even cooling of the filaments guided in the outer area, the setting in which the flow velocity at the outlet of the pre-cooling air stream is at least twice as high as the flow velocity at the outlet of the jacket air stream has proven useful.

In particular, a pre-cooling air flow generated by an annular gap nozzle had the best effect. For this purpose, the annular gap nozzle has an annular nozzle opening formed at a distance from the filaments. In particular, it was possible to completely displace the warm air carried in the filament curtain, which in particular has improved the further cooling of the filaments by the jacket air flow.

In order to ensure that both the pre-cooling and the further cooling of the filaments can take place with optimized air flows, provision is made according to an advantageous further development to set the pre-cooling air flow and the jacket air flow independently of one another.

To carry out the method, the device according to the invention has an additional coolant between the spinneret and the blow candle, by means of which an additional pre-cooling air flow for pre-cooling the filaments is generated.

In this case, the additional coolant and the blow candle can both be connected together to an air supply device or can be supplied in each case by separate air supply devices. In order to keep a pre-cooling air stream flowing with the highest possible flow velocity compared to the jacket air stream, the coolant is preferably designed as an annular gap nozzle, in which the pre-cooling air stream exits through a nozzle opening arranged in a ring at a distance from the filaments. Intensive pre-cooling of the extruded filaments can be achieved in particular by keeping the distance between the nozzle opening of the annular gap nozzle and the filaments smaller than the distance between the jacket of the blow candle and the filaments.

Furthermore, the flow rate of the pre-cooling air can be influenced in that the nozzle opening is variable in its gap height.

The additional coolant can be firmly connected either directly below the spinneret or directly to the blow candle.

The method according to the invention is described in more detail below with reference to some exemplary embodiments of the device according to the invention with reference to the accompanying drawings.

They represent:

Fig. 1 shows schematically a cross-sectional view of a first embodiment of the device according to the invention.

Fig. 2 schematically shows a cross-sectional view of another

Embodiment of the device according to the invention

3 and 4 schematically show a cross-sectional view of further exemplary embodiments of the device according to the invention

1 schematically shows a first exemplary embodiment of the invention

Device shown in a cross-sectional view. The device has a spinneret 1, which is arranged within a heated spinning beam 2. The

Spinneret 1 is annular, preferably circular or rectangular and arranged on the underside of the spinning beam 2. The spinneret 1 is coupled to a spinning pump 4 by melt distribution lines 3. A polymer melt is fed to the spinning pump 4 via a melt feed 5, for example by an extruder. The underside of the spinneret 1 has a multiplicity of nozzle bores (not shown here), from each of which a filament is extruded in the form of a strand.

A coolant 6 in the form of a blowing is arranged on the underside of the spinning beam 2. For this purpose, the blowing 6 has an annular blowing chamber 8 and a blowing wall 10 covering the blowing chamber 8 towards the outside. The blowing 6 is dimensioned such that there is a distance between the filament sheet 18 extruded through the spinneret 1 and the blowing wall 10. The coolant 6 is connected to a first air supply 7, which penetrates the spinning beam 2 and the spinneret 1. The air supply 7 is connected to the blow chamber 8 via air distribution lines 9.

A blow candle 12 is arranged below the coolant 6 and bears against a coolant 6 at its upper end via a centering stop 11. At the opposite end abuts the coolant 6 via a centering stop 11. The blow candle 12 is connected to a holding device 13 at the opposite end. The blow candle 12 has a porous jacket 15, which can be produced, for example, from a nonwoven, foam, sieve fabric or a sintered material. The holding device 13 is connected to a second air supply 14, the interior of the blow candle 12 being coupled to the air supply 14 via the holding device 13. The holding device 13 is preferably designed to be movable in order to guide the blow candle 12 out of or into the spinning line for maintenance or cleaning or replacement.

The holding device 13 has, below the blow candle 12, a preparation ring 17 which is contacted by the filament sheet 18 in order to apply a preparation agent to the filaments. In the device shown in FIG. 1, a polymer melt is supplied under pressure by the spinning pump 4 during operation of the spinneret 1. In this case, strand-like filaments emerge on the underside from the nozzle bores of the spinneret 1, which form a filament family 18. The filament sheet 18 is guided in a ring and drawn off from the spinneret 1 together by a drawing mechanism (not shown here).

Shortly below the spinneret 1, a pre-cooling air flow 19 is blown radially from the inside out through the filament sheet 18 by the coolant 6 designed as a blowing. The intensity of the pre-cooling air flow 19 can be regulated directly via the air supply 7. The pre-cooling air flow 19 is set in such a way that each of the filaments guided within the filament array is given a uniform cooling effect. In addition, the filament curtain is widened, so that the individual filaments in the filament curtain can be flushed uniformly by the following jacket air stream.

To solidify the filaments, there is further cooling by the jacket air stream 16 of the blow candle 12

Spinning speeds of over 800 m / min. uniform and sufficient cooling of the filaments is achieved. In order to obtain an intensive and uniform pre-cooling of the filaments, the flow rate of the pre-cooling air stream is set higher than the flow rate of the jacket air stream. For this purpose, the distance between the blowing wall 10 and the filament sheet 18 is set to be substantially smaller than the distance between the jacket 15 and the filament sheet 18.

However, the method according to the invention is preferably carried out with a device such as that shown in FIG. 2. Here, the

Pre-cooling air flow through a coolant designed as an annular gap nozzle 20 generated. The pre-cooling air flow emerging from a nozzle opening 21 creates a relatively strong blowing wind in order to effect pre-cooling in the filament family. In the following description of the embodiment of FIG. 2, the components with the same function have been identified with identical reference numerals. 2, an annular spinneret 1 is coupled to a spinning pump 4 via a melt distributor 30. The spinning pump 4, the melt distributor 30 and the spinneret 1 are arranged in a heated spinning beam 2.

An additional coolant designed as an annular gap nozzle 20 is arranged below the spinneret 1. The annular gap nozzle 20 is firmly connected to the blow candle 12. For this purpose, the blow candle 12 has a head plate 25 at the free end. The annular gap nozzle 20 is collar-shaped at the free end of the blow candle 12 and firmly connected to the head plate 25. The circumferential annular nozzle opening 21 of the annular gap nozzle 20 is formed between a perforated plate 23 and a cover plate 24, which are braced against one another via a sealing ring 22. The gap height of the nozzle opening 21 is determined by the thickness of the sealing ring 22. Thus, any gap height of the nozzle opening 21 on the annular gap nozzle 20 can be set by exchanging and changing the sealing ring 22. The nozzle opening 21 is connected to the interior of the blow candle 12 via bores in the perforated plate 23 and the top plate 25. Thus, the annular gap nozzle 20 and the blow candle 12 are fed via a common air supply 14. The annular gap nozzle 20 and the blow candle 12 are held by a holding device 13 with a centering stop 11 on the underside of the spinning beam 2.

The blow candle 12 is designed to be axially displaceable relative to the holding device 13, the blow candle 12 being held in an operating position by a force sensor 27 acting in the axial direction. Such an axially adjustable blow candle is known from EP 1 231 302 AI, so that on this Reference is made to this publication. The blow candle 12 is held at its lower end on a connector 26 which is slidably guided in a centering opening 28 of the holding device 13. In this exemplary embodiment, the force transmitter 27 is designed as a compression spring which enables the blow candle to be axially displaced for replacement.

The further structure of the device according to FIG. 2 is identical to the structure of the device according to FIG. 1, so that reference is made to the previous exemplary embodiment.

To cool the filaments, a cooling air flow is supplied to the blow candle 12 via the air supply 14 and the holding device 13. Part of the cooling air flow reaches the annular gap nozzle 20 directly at the free end via the bores of the top plate 25. A relatively sharp pre-cooling air flow then emerges from the nozzle opening 21, which emerges at a short distance from the filament sheet 18 and penetrates the filament sheet 18. At the same time, a radially directed jacket air flow emerges from the porous jacket 15 of the blow candle 12. In experiments it was found that with a common air supply, an exit speed of the pre-cooling air of approx. 10 m / sec. compared to an exit velocity of the jacket air flow of 3 m / sec. established. This made it possible to produce staple fibers with a final titre of 0.6 dtex. aufweisten. With a standard version of the blow candle without additional coolant and under the same air supply conditions, only fibers with a final titer of above 0.9 dtex could. getting produced. Due to the frequent occurrence of filament breaks, finer titers could not be reliably produced. It was only through the process according to the invention that fibers with fine titanium could be reliably produced without the occurrence of filament breaks. A further optimization of the pre-cooling of the filaments could also be achieved by changing the gap height of the nozzle opening 21 of the annular gap nozzle 20. The gap height was in the range from 0.1 to 0.9 mm. 3 shows a further exemplary embodiment of a device according to the invention for carrying out the method according to the invention. The exemplary embodiment in FIG. 3 is essentially identical to the previous exemplary embodiment according to FIG. 2. In this respect, reference is made to the preceding description and only the differences are shown at this point.

In the embodiment shown in FIG. 3, the additional coolant is also designed as an annular gap nozzle 20, which is arranged in a collar at the free end of the blow candle 12. The structure of the annular gap nozzle 20 is identical to the exemplary embodiment of the annular gap nozzle in FIG. 2.

An air supply line 29 is arranged within the blow candle 12 and has one end connected to the bores in the top plate 25. At the other end, the air supply line 29 is connected to the air supply 7. The annular gap nozzle 20 can thus be supplied independently of the cooling air supply to the blow candle 12 with a cooling air flow. The blow candle 12 is coupled to the air supply 14 via the holding device 13. The pre-cooling air flow and the jacket air flow for cooling the filaments can thus be set independently of one another. In addition, different cooling media or different compositions of the cooling air could also be used to cause the filaments to solidify.

Another embodiment of the device according to the invention is shown schematically in FIG. 4. The exemplary embodiment differs essentially in that a blow candle 12 is held on the underside of a spinning beam 2, as is known, for example, from EP 1 247 883 A2. With regard to the structure and function of such a device, reference is expressly made here to the content of the cited publication. In the following description of the exemplary embodiment relating to FIG. 4 the components of the same function have been identified with the identical reference numerals of the preceding exemplary embodiments.

4, an annular spinneret 1 is coupled to a spinning pump 4 via melt distribution lines 31. The spinning pump 4 is driven by the drive shaft 33. The spinning pump 4, the distribution lines 31 and the spinneret 1 are arranged in a heated spinning beam 2. An annular gap nozzle 20 is arranged below the spinneret 1 as an additional coolant. The annular gap nozzle 20 is firmly connected to a blow candle 12 on its underside. The annular gap nozzle 20 and the blow candle 12 are coupled to the side facing the spinning beam 2 on an air supply. Here, a first air supply 7 is formed by an inner air supply line 29 which penetrates the spinning beam 2 and projects into the blow candle 12. The inner air supply line 29 is encased by an outer air supply line 32, which is coupled to the annular gap nozzle 20. A second air supply 14 is fed to the annular gap nozzle 20 in this way.

The annular gap nozzle 20 is formed by a perforated plate 23 and a top plate 25 arranged below the perforated plate. The perforated plate 23 has an inlet which is connected to the nozzle opening 21 between the perforated plate 23 and the top plate 25. The blow candle 12 connects to the top plate 25.

A preparation device in the form of a preparation ring 17 is formed below the blow candle 12, which preparation ring 17 encloses a filament sheet 18 extruded through the spinneret 1. Here, the filament sheet 18 is guided along an inner contact surface of the preparation ring 17. In the embodiment shown in FIG. 4, the filaments of the filament sheet 18 freshly extruded through the spinneret 1 are first cooled after exiting the spinneret 1 by the pre-cooling air flow 19 which is generated by the annular gap nozzle 20. After intensive pre-cooling, the filament sheet 18 is then further cooled by the jacket air flow 16, which is generated by the jacket 15 of the blow candle 12. As already described above, the gap height of the nozzle opening 21 of the annular gap nozzle 20 can be changed in order to be able to adjust the intensity of the pre-cooling of the filament sheet 18 to certain conditions.

The devices shown in the exemplary embodiments according to FIGS. 1 to 4 are exemplary in their construction and can be combined optionally. For example, a coolant designed as an annular gap nozzle could be arranged directly below the spinning beam, as shown in the exemplary embodiment in FIG. 1. However, it is also possible to design the coolant with a plurality of annular nozzle openings which are arranged one behind the other at short intervals. It is essential for the invention that an intensive pre-cooling air flow for pre-cooling the filaments can be generated just below the spinneret and that a longer cooling of the filaments ensues due to a blow candle.

LIST OF REFERENCE NUMBERS

spinneret

spinning beam

Melt distribution line

spinning pump

melt inlet

coolant

First air supply

puffer

Air distribution line

blowing wall

Centering stop

blow candle

holder

Second air supply

coat

Outer air stream

finishing ring

filament bundle

precooling

annular die

nozzle opening

seal

perforated plate

cover plate

headstock

connector

force transmitter

centering Air supply line

Melt distributor

distribution lines

Outer air supply line

drive shaft

Claims

claims

1. A process for melt spinning and cooling a plurality of synthetic filaments, in which the filaments are extruded in an annular arrangement by means of a spinneret, in which the filaments are guided at a distance from a blow candle and in which the filaments are passed radially out of the jacket of the Sheathed air stream emerging from the spark plug candle, characterized in that the filaments are precooled by an additional precooling air stream before being cooled by the jacket air stream.

2. The method according to claim 1, characterized in that the pre-cooling air flow and the jacket air flow rectified to the

Filaments hit, the flow rate of the pre-cooling air flow being higher than the flow rate of the jacket air flow.

3. The method according to claim 2, characterized in that the flow rate at the exit of the pre-cooling air flow is at least twice as high as the jacket air flow.

4. The method according to any one of claims 1 to 3, characterized in that the pre-cooling air flow through a

Annular gap nozzle is generated, which has an annular nozzle opening formed at a distance from the filaments.

5. The method according to any one of claims 1 to 4, characterized in that the pre-cooling air flow and the jacket air flow are independently adjustable.

Device for carrying out the method according to one of claims 1 to 5, with a spinneret (1) and a blow candle (12) arranged below the spinneret (1), which generates a jacket air stream radially emerging from the jacket (15) for cooling the filaments, characterized in that an additional coolant (6, 20) is arranged between the spinneret (1) and the blow candle (1), through which an additional pre-cooling air flow for pre-cooling the filaments can be generated.

Apparatus according to claim 6, characterized in that the additional coolant (20) and the blow candle (12) are connected to a common air supply (14).

8. The device according to claim 6, characterized in that the additional coolant (6, 20) and the blow candle (12) are connected to independently controllable air supply (7, 12).

9. Device according to one of claims 6 to 8, characterized in that the coolant is designed as an annular gap nozzle (20) which has an annular nozzle opening (21) arranged at a distance from the filaments.

10. The device according to claim 9, characterized in that the distance between the nozzle opening (21) of the annular gap nozzle (20) and the filaments (18) is substantially smaller than the distance between the jacket (15) of the blow candle (12) and the filaments (18).

11. The device according to claim 9 or 10, characterized in that the nozzle opening (21) of the annular gap nozzle (20) has a variable gap height.

12. Device according to one of claims 6 to 11, characterized in that the additional coolant (20) is fixedly connected to the blow candle (12).

13. The apparatus according to claim 12, characterized in that the annular gap nozzle (20) is formed in a surrounding the collar of the blow candle (12).

14. The device according to one of claims 6 to 13, characterized in that the blow candle (12) is held on a holding device (13) such that the blow candle (12) relative to the

Holding device (13) is axially adjustable between an operating position and a waiting position and is held clamped in the operating position between the holding device (13) and the coolant (6, 20) or the spinneret (1).