EP3382081B1 - Device for the manufacture of woven material from continuous filaments - Google Patents

Description

The invention relates to a device for producing spunbonded nonwovens from continuous filaments, in particular continuous filaments of thermoplastic material, with at least one spinnerette for spinning the filaments, at least one cooling device for cooling the filaments, at least one drawing device for stretching the filaments and at least one depositing device for filing the filaments Filaments to the nonwoven web. - Endless filaments means within the scope of the invention filaments with quasi endless length. These continuous filaments differ from staple fibers in that they have much smaller lengths of, for example, 10 to 60 mm.

Devices of the aforementioned type are known in practice in principle in different embodiments. Such devices are also referred to as spunbond devices. Many of the devices known from practice of this type have the disadvantage that at high filament speeds and high throughputs or production speeds, the quality of the Filamentablage leaves something to be desired. This applies in particular to the homogeneity of the deposit as well as the strength of the nonwoven webs produced. High filament speeds and low titers of the filaments produced can often only be realized with significant losses in quality of the nonwoven webs produced. In that regard, the known devices can be improved.

Out WO 2014/064029 A1 a device for the production of spunbonded filaments is known, wherein the device also has a spinnerette, a cooling device, a drawing device and a filing device for depositing the filaments. Between the drawing device and the Storage device is a diffuser interposed and on the diffuser two secondary air inlet column for the entry of secondary air are present. However, this device leaves something to be desired with regard to the quality of the filament deposit.

The same applies to one EP 2 584 076 A1 known device. This device also has the components described above for producing continuous filaments. Incidentally, diffusers are provided, and in the lower part of the device there is a structural component having a convergent and a divergent section. The filament deposit or the deposited nonwoven also does not meet the requirements in terms of the desired quality.

Also from EP 1 630 265 A1 An apparatus for producing spunbonded nonwoven filaments is known. This device also has the system components described above. Diffusers are provided which are composed of convergent diffuser sections and divergent diffuser sections and a constriction is formed therebetween. This device has proven itself in principle. Nonetheless, there are opportunities for change and opportunities for improvement.

Accordingly, the invention addresses the technical problem of specifying a device of the type mentioned, in which high filament speeds and low titers and high production speeds can be realized and nonetheless the quality of the filament deposit or the nonwoven web produced meets all requirements.

To solve this technical problem, the invention teaches a device for producing spunbonded non-wovens, in particular of thermoplastic material, with at least one spinnerette for spinning the filaments, at least one cooling device for cooling the filaments, at least one drawing device for stretching the filaments and at least one Storage device, in particular in the form of a storage screen belt, for depositing the filaments to the nonwoven web,
wherein between the drawing device and the depositing device or the Ablagesiebband at least one diffuser is arranged so that filaments and primary air from the drawing device into the diffuser, wherein at least two arranged on opposite sides of the diffuser secondary air inlet gaps are provided in the region of the at least one diffuser through which secondary air enters the diffuser,
wherein at least one secondary air inlet gap, preferably at least two secondary air inlet gaps are formed with the proviso that the secondary air flows in an inflow angle α to the filament flow direction FS and to the longitudinal center plane M of the device or the diffuser, said inflow angle α less than 100 ° , is advantageously less than or equal to 90 °, preferably less than 80 °, preferably less than 70 ° and particularly preferably less than 65 °,
wherein in the flow direction of the filaments behind or under the secondary air inlet columns, a convergent diffuser section connects,
wherein in the direction of flow of the filaments to the convergent diffuser section connects a constriction of the diffuser and wherein the bottleneck is followed by at least one divergent diffuser section,
wherein the convergent diffuser section is made shorter than the divergent diffuser section and wherein the length of the convergent diffuser section is at most 60% of the length of the divergent diffuser section,
the last diffuser section in the filament flow direction FS having divergent diffuser walls towards the depositing device, said diffuser walls forming a diffuser exit having a width B with respect to the machine direction (MD),
wherein at least one suction device for extracting air or process air through the depositing device or through the Ablagesiebband is provided and wherein a below the diffuser outlet disposed suction region has a width b in the machine direction (MD), which width b is greater than the width B of the diffuser exit , - Machine direction (MD) means in the context of the invention, in particular the conveying direction of the filament or the nonwoven web on the storage device or on the Ablagesiebband.

It is within the scope of the invention that the suction area extends with its width b below the diffuser over the entire width B of the diffuser outlet. It is also within the scope of the invention that the suction area is limited by two partitions arranged one behind the other in the machine direction. The width b of the suction region is measured, in particular, between the upper ends of the two partitions in the machine direction, facing the depositing device or the depositing screen belt. Appropriately, at least one suction fan is provided with the process air in the suction through the storage device or is sucked through the filing screen belt. According to one embodiment of the invention, a plurality of suction regions can be arranged one after the other in the machine direction-for example, three suction regions-which differ from one another, in particular with respect to their extraction speed. Then it is in the claimed in claim 1 suction to the arranged under the diffuser outlet or directly below the diffuser outlet Hauptabsaugbereich. In principle, the suction area or main suction area arranged below the diffuser outlet or directly below the diffuser outlet can in turn be subdivided, for example by partitions. Then, this suction or Hauptabsaugbereich is characterized in that the suction speed over the entire width b of the suction is equal or substantially equal. Conveniently, the mean suction speed in the suction or Hauptabsaugbereich not more than 20%, in particular not more than 30% or not more than 40% and especially not more than 50%. In this context, it is within the scope of the invention that in an additional suction area arranged upstream of the suction area or main suction area according to an embodiment variant with respect to the machine direction (MD) and / or additional suction space arranged behind the suction area or main suction area with respect to the machine direction (MD). Absaugbereich a suction speed is present, which is different from the suction speed of the suction or Hauptabsaugbereiches.

According to a particularly recommended embodiment of the invention, the width b of the suction region is at least 1.2 times, preferably at least 1.3 times and particularly preferably at least 1.4 times the width B of the diffuser outlet. According to one embodiment variant, the width b of the suction region can be at least 1.5 times, in particular at least that Be 1.6 times or at least 1.7 times the width B of the diffuser exit.

A very preferred embodiment of the device according to the invention is characterized in that the suction region with respect to the machine direction (MD) extends beyond the storage area of the filaments around a first suction section across the width of the diffuser outlet and / or wherein the suction region with respect to the machine direction (MD) in front of the storage area the filaments extend beyond a second suction section over the width of the diffuser exit. Preferably, the suction area or the Hauptabsaugbereich protrudes on both sides with respect to its width b beyond the width B of the diffuser outlet on the one side to the first suction and on the other side to the second suction section. Expediently, the width b _{1 of} the first suction section and / or the width b _{2 of} the second suction section is 2 to 30%, preferably 2.5 to 25% and particularly preferably 3 to 20% of the width B of the diffuser outlet.

A highly recommended embodiment of the invention is characterized in that the suction takes place by means of the suction device with the proviso that at least in the region of the diffuser outlet tertiary air flows along the outer surfaces of the diffuser walls in the direction of storage device or Ablagesiebband and at least a portion of this tertiary air the storage device or is sucked through the Ablagesiebband. It is within the scope of the invention that the tertiary air flows are aligned parallel or substantially parallel to the mixed flow of primary air and secondary air flowing in the direction of the diffuser outlet in the interior of the diffuser. It is recommended that the volume flow of the tertiary air V _T extracted with the suction device is at least 25%, preferably at least 30%, preferably at least 40% and particularly preferably at least 50% of the volume flow of the extracted primary and secondary air flows. The preferred extraction of the tertiary air described above has proved successful insofar as unwanted turbulence in the storage area of the filaments can be avoided as a result.

According to the invention, the continuous filaments are produced with a spunbond apparatus. It is within the scope of the invention that the cooling device, the drawing device and the at least one diffuser extend transversely to the machine direction (MD) over the production width or over the width (DC width) of the nonwoven web to be produced. According to a particularly preferred embodiment of the invention, the unit of cooling device and drawing device is designed as a closed unit and except the supply of cooling air in the cooling device finds no further supply of a fluid medium or no further air supply in this closed unit of cooling device and drawing device instead. This closed unit or this closed system has proven particularly useful in the context of the invention and contributes effectively to the solution of the technical problem.

The cooling device of the device according to the invention can only have a cooling chamber in which the filaments are exposed to cooling air or process air of a certain temperature. According to a further embodiment of the invention, the cooling device has two superposed or successively arranged cooling chambers. In these two cooling chambers, the filaments can each be charged with cooling air or process air of different temperatures. The device can also be set up with the proviso that the exit velocity of the process air from a upper cooling chamber for cooling the filaments and the exit velocity from a lower cooling chamber is different.

Of particular importance in the context of the invention are the secondary air inlet gaps or the secondary air introduced through these secondary air inlet gaps. It is within the scope of the invention that the secondary air inlet gaps extend across the entire width of the device transversely to the machine direction (in the CD direction). According to a very preferred embodiment of the invention, two opposing secondary air inlet gaps are arranged between the drawing device and the diffuser adjoining the drawing device. According to one embodiment of the invention, two diffusers are arranged one behind the other in the filament flow direction FS and two opposite secondary air inlet gaps are provided between the two diffusers. -Two secondary air inlet gaps can be arranged at the same vertical height. However, it is also within the scope of the invention that the secondary air inlet gaps are provided at different vertical heights of the device. According to a preferred embodiment of the invention, only two opposing secondary air inlet gaps are present, and more preferably between drawing device and diffuser.

Particular importance is still attached to the inflow angle α of the secondary air. According to the invention, at least one secondary air inlet gap and preferably at least two secondary air inlet gaps, particularly preferably two secondary air inlet gaps are formed with the proviso that the secondary air flows in an inflow angle α to the filament flow direction FS. A recommended embodiment is characterized in that the inflow angle α is less than 90 °, preferably less than 80 °, preferably less than 70 ° and particularly preferably less than 65 °. That's it particularly proven that the inflow angle α is less than 60 °, preferably less than 55 ° and very preferably less than 50 °. According to a highly recommended embodiment, the inflow angle α is between 0 and 60 °, advantageously between 1 and 55 °, preferably between 2 and 50 °, very preferably between 2 and 45 ° and particularly preferably between 2 and 40 °. It is particularly recommended that the inflow of the secondary air is carried out with the proviso that the secondary air flows after their entry parallel or quasi parallel to the filament flow direction FS.

The secondary air inlet gaps are expediently set up correspondingly for realizing the inflow angle α, in particular with the aid of inflow slopes and / or inflow channels and the like. According to a preferred embodiment, an oblique inflow wall adjoining or connected to a diffuser wall of the diffuser is provided for realizing the inflow angle α in the area of a secondary air inlet gap, which inflow wall encloses an angle with the filament flow direction FS which corresponds or essentially corresponds to the inflow angle α. In this embodiment, a corresponding inflow wall is preferably provided for each secondary air inlet gap. Such an inflow wall is recommended to form an inflow slope for realizing the inflow angle α. The realization of the inflow angle α according to the invention has proven particularly useful in the context of the invention and contributes effectively to the solution of the technical problem. In combination with the embodiment of the suction region according to the invention, a high-quality filament deposit and a particularly homogeneous nonwoven web can be obtained. Of particular importance in the context of the combination of the features of the device according to the invention also the closed system or the design of the unit of cooling device and drawing device as a closed unit.

In the context of the invention, primary air means the process air which is passed through the drawing device and exits from the drawing device or from the drafting shaft of the drawing device into the diffuser. A very preferred embodiment of the invention is characterized in that in the region of the secondary air inlet column, the ratio of the volume flows of primary air and secondary air V _P / V _{S is} less than 5, preferably less than 4.8 and preferably less than 4.5. According to the recommended embodiment of the invention, the volume flow of the secondary air entering through the secondary air inlet gaps is adjustable, preferably adjustable for each secondary air inlet gap and independently adjustable according to a variant embodiment. It is recommended that this is the cross section of the secondary air inlet column variable or adjustable. Expediently, the volume flow of secondary air entering through two secondary air inlet gaps arranged on opposite sides of the diffuser is equal to or substantially equal to or up to a maximum of 15%, in particular up to a maximum of 20% different. The vertical height of the secondary air inlet gaps is preferably 2 to 20 mm, preferably 3 to 18 mm and particularly preferably 5 to 15 mm. An embodiment of the invention is characterized in that the volume flow of the secondary air entering through the secondary air inlet gaps can be adjusted or varied over the CD width (transversely to the machine direction MD). For this purpose, the vertical height of the secondary air inlet gap is expediently set or changed over the CD width (transversely to the machine direction MD). The setting of the secondary air volume flows is recommended, provided that the volume flow of the incoming secondary air with respect to the CD direction to the edges of the device or to the edges of the secondary air inlet column decreases. Preferably, the secondary air volume flow entering through the secondary air inlet gaps is merely in the edge regions of the secondary air inlet column lower than in the central region of the secondary air inlet column. These margins are recommended to have a length of 5 to 20 cm. A maximum of 75%, preferably a maximum of 80%, of the secondary air volume flow which occurs in the central region of the secondary air inlet gap is expediently supplied in the edge regions. Within the scope of the invention, it is preferred that a uniform inflow of secondary air through the secondary air inlet gaps takes place transversely to the machine direction or in the CD width of the device, namely according to a variant embodiment of the invention, apart from the abovementioned edge regions, expediently in the entire central region of the secondary air -Eintrittsspalte. Insofar as the invention is based on the recognition that a particularly homogeneous Filamentablage can be achieved or a very homogeneous Filamentablage can be achieved over the CD width.

According to the invention, a convergent section of a diffuser or of the diffuser adjoins behind or under the secondary air inlet gaps in the filament flow direction. In the filament flow direction behind or under the secondary air inlet columns, a convergent section of the diffuser is first arranged, then a constriction of the diffuser closes and behind and under the constriction a divergent section of the diffuser is provided (convergent - constriction - divergent). In the bottleneck as it compacts the inflowed secondary air or the primary air-secondary air mixture. According to the invention, the convergent section of the diffuser is made shorter or significantly shorter than the divergent section of the diffuser. The length I _{K of} the convergent diffuser section is at most 60% and preferably at most 50% of the length I _{D of} the divergent section of this diffuser. It is recommended that the length I _{K of} the convergent section of the diffuser amounts to a maximum of 40%, preferably a maximum of 35% and preferably a maximum of 30% of the length I _{D of} the divergent diffuser section. The ratio I _K / I _{D of} the length I _{K of} the convergent diffuser section to the length I _{D of} the divergent diffuser section is expediently 0.1 to 1 and preferably 0.15 to 0.9. It is recommended that the length I _{K of} the convergent diffuser section is 5 to 50% and preferably 10 to 50% of the length L of the entire diffuser.

It is within the scope of the invention that the diffuser exit angle β of the diffuser outlet - or of the last diffuser section arranged in the filament flow direction over the depositing device - is at most 30 °, preferably at most 25 ° and very preferably at most 20 °. The diffuser exit angle β is measured between a diffuser wall of the divergent diffuser section and the longitudinal center axis M of the diffuser. Preferably, the diffuser walls of the diffuser outlet forming divergent diffuser section are formed pivotable, so that the diffuser exit angle β is variable or adjustable. It is recommended that the width B of the diffuser outlet of the divergent diffuser section is at most 300%, preferably at most 250% and preferably at most 200% of the width V _{B of} the exit slit of the drawing device or of the drawing shaft of the drawing device. - A particularly preferred embodiment of the invention is characterized in that the distance of the diffuser or the lower edge - in particular the lowermost lower edge - of the diffuser to the storage device or the Ablagesiebband 20 to 300 mm, in particular 30 to 150 mm and preferably 30 to 120 mm is.

It is within the scope of the invention that a monomer suction device is arranged between the spinnerette and the cooling device. With this Monomerabsaugungsvorrichtung air is sucked from the Filamentbildungsraum below the spinnerette. This allows the next to the Continuous filaments emerging gases such as monomers, oligomers, decomposition products and the like are removed from the device according to the invention. The Monomerabsaugungsvorrichtung expediently has at least one suction chamber, to which preferably at least one suction fan is connected. The at least one suction chamber is provided towards the filament forming space with at least one suction slot for the suction of said gases. A particularly effective solution to the technical problem is further provided by a preferred embodiment of the invention, characterized in that at least a first deformable seal is arranged between the spinnerette and the monomer suction device for sealing a first gap formed between the spinnerette and the monomer suction device, and / or wherein at least one second deformable seal for sealing a second gap formed between the monomer suction device and the cooling device is provided between the monomer suction device and the cooling device and / or at least one third deformable seal for sealing between the cooling device and the drawing device or an intermediate channel of the drawing device a arranged between the cooling device and the drawing device or the intermediate channel third gap is arranged. Preferably, the system properties, in particular the contact pressure or the contact pressure of such a deformable seal with respect to the boundary areas or boundary surfaces of the respective gap are variable or adjustable. Such a preferred deformable seal extends recommended over the entire width or over the entire CD width (transverse to the machine direction) of the device according to the invention. It is within the scope of the invention that such a deformable seal rotates over the entire circumference or substantially over the entire circumference of the filament flow passage. It is also in the According to the invention, the height h of a gap to be sealed with a deformable seal is 3 to 35 mm, in particular 5 to 30 mm, and that the at least one deformable seal seals over this height h of the gap. Expediently, irregularities with respect to the height h of the gap can be compensated for by variation or adjustment of the system properties of the seal in this height direction. It is recommended that the seal with a fluid medium is filled or filled and that the adjustment or adjustment of the seal by introducing the fluid medium into the seal or by discharging the fluid medium from the seal. Preferably, the at least one deformable seal is an inflatable seal. According to another embodiment, the deformable seal may also have at least one by means of at least one spring element to a boundary surface of the gap to be sealed pressed sealing element. The sealing element may in particular be a sealing lip and thus a spring-loaded sealing lip in the case of the seal. The spring element is then expediently fixed to a boundary surface of the gap to be sealed and presses the sealing element or the sealing lip against the opposite boundary surface of the gap. Preferably, the at least one deformable seal is designed with the proviso that sealing takes place at a pressure in the filament flow channel of more than 2,000 Pa, in particular of more than 2,500 Pa. The embodiment with the deformable seal has proven particularly useful in the context of the teaching according to the invention. In combination with the other inventive or preferred features of the device according to the invention optimum aerodynamic conditions in the device, which effectively contribute to solving the technical problem of the invention.

The invention is based on the finding that with the device according to the invention nonwoven webs or spunbonded nonwovens of outstanding quality can be produced. Above all, with the aid of the teaching according to the invention, a homogeneous filament deposit and thus a homogeneous nonwoven web can be produced both in the machine direction and also transversely to the machine direction. An optimal homogeneous nonwoven storage can be achieved especially at higher or at high production speeds. With the device according to the invention high filament velocities and thus low titers of the filaments can be realized, nevertheless good good filament deposition. High filament speeds and low titers can be achieved without difficulty at high throughputs or production speeds of, for example, more than 400 m / min. It should be emphasized that the device according to the invention is nonetheless relatively simple and of little complexity.

Fig. 1

einen Vertikalschnitt durch eine erfindungsgemäße Vorrichtung und

Fig. 2

einen vergrößerten Ausschnitt A des unteren Bereichs der erfindungsgemäßen Vorrichtung aus Fig. 1.

The invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. In a schematic representation:

Fig. 1

a vertical section through a device according to the invention and

Fig. 2

an enlarged section A of the lower portion of the device according to the invention from Fig. 1 ,

The figures show a device according to the invention for producing spunbonded nonwovens from continuous filaments 1, in particular from continuous filaments 1 made of thermoplastic material. The device has a spinnerette 2 for spinning the continuous filaments 1 and a cooling device 3 for cooling the filaments. Between the spinnerette 2 and the cooling device 3 is a monomer extraction device 4 is arranged according to a particularly preferred embodiment of the invention. With this Monomerabsaugungsvorrichtung 4 occurring in the spinning process disturbing gases can be removed from the device. These may be, for example, monomers, oligomers or decomposition products and the like substances. Between the Monomerabsaugungsvorrichtung 4 and the cooling device 3, a gap 5 is formed, which usually rotates around the entire Filamentbildungsraum or Filamentströmungsraum. After a very preferred embodiment and in the embodiment of the figures (see in particular Fig. 1 ) is arranged between the Monomerabsaugungsvorrichtung 4 and the cooling device 3, at least one deformable seal 6 for sealing said gap 5. The at least one deformable seal 6 expediently circulates in the gap 5 over the entire filament-forming space or filament flow space. It is within the scope of the invention that the system properties, in particular the contact pressure or the contact pressure of the seal 6 with respect to the boundary surfaces of the gap 5 can be varied or adjusted. The vertical height h of the gap 5 in the exemplary embodiment may be 5 to 30 mm and the at least one deformable seal 6 seals the gap 5 via this vertical height h of the gap 5. Preferably, and in the exemplary embodiment, the at least one deformable seal 6 is a seal 6 that can be inflated with a fluid medium. By supplying or discharging the fluid medium-preferably air-the system properties, in particular the contact pressure or contact pressure of the seal 6 can be achieved be varied.

In the exemplary embodiment (see in particular Fig. 1 ), the cooling device 3 has two superposed or successively arranged cooling chambers, in which the filaments can be acted upon in particular with process air or cooling air of different temperature. Basically, is in the frame the invention but also a cooling device 3 with only one cooling chamber possible.

The cooling device 3 is followed by a drawing device 7 for stretching the filaments 1 in the filament flow direction FS. Preferably and in the exemplary embodiment, the cooling device 3 is adjoined by an intermediate channel 8, which connects the cooling device 3 to a drawing shaft 9 of the drawing device 7. According to a preferred embodiment and in the embodiment, the unit from the cooling device 3 and the drawing device 7 and the unit from the cooling device 3, the intermediate channel 8 and the drawing shaft 9 is formed as a closed system. Apart from the supply of cooling air in the cooling device 3 no further air supply takes place in this unit. The guided through the drawing device 7 and through the drawing tray 9 air is referred to here and below as the primary air P.

According to the invention, at least one diffuser 10 adjoins the drawing device 7 in the filament flow direction FS. Preferably, in the exemplary embodiment, two opposing secondary air inlet gaps 11, 12 for the introduction of secondary air S are arranged between drawing device 7 or between drawing shaft 9 and the diffuser 10. Expediently, the secondary air inlet gaps 11, 12 extend over the entire width or CD width of the device according to the invention. According to the secondary air is introduced through the secondary air inlet column with an inflow angle α, which is less than 100 °, advantageously less than or equal to 90 °, preferably less than 80 ° and less than 45 ° in the embodiment. According to a highly recommended embodiment of the invention, the inflow angle α is between 0 and 60 °, preferably between 2 and 50 °. For the realization of the inflow angle α are in the embodiment (see in particular Fig. 2 ) provided corresponding inflow guides 13, which are formed in the embodiment as obliquely connected to the secondary air inlet gaps 11, 12 inflow channels 14. In this case, the inflow channels 14 form an angle with the filament flow direction FS or with the longitudinal center axis M, with the proviso that the secondary air can flow in at the indicated inflow angle α. According to a particularly preferred embodiment, a quasi-parallel inflow of secondary air to the filament flow direction FS takes place.

According to a particularly recommended embodiment of the invention, the volume flow of secondary air supplied through the secondary air inlet gaps 11, 12 can be adjusted. This can be realized in particular by adjusting the cross sections of the secondary air inlet gaps 11, 12. In principle, different volumetric flows of supplied secondary air S can also be set for the two opposing secondary air inlet gaps 11, 12. According to one embodiment of the invention, the secondary air volume flow flowing through the secondary air inlet gaps 11, 12 can be adjusted or varied transversely to the machine direction or over the CD width, preferably with respect to each secondary air inlet gap 11, 12. Expediently, the supplied secondary air volume flow in the edge regions of the device or the secondary air inlet gaps 11, 12 is different in comparison to the central region of the device or to the central region of the secondary air inlet gaps 11, 12.

Due to the entry of the secondary air S through the secondary air inlet gaps 11, 12 10 primary air P is mixed with secondary air S in the subsequent diffuser. According to a preferred embodiment of the invention, in the region of the secondary air inlet gaps 11, 12, the ratio of the volume flows of Primary air and secondary air V _P / V _S less than 5 and preferably less than 4.5.

In the embodiment according to the figures, only a diffuser 10 in the filament flow direction FS below the drawing device 7 is present. In principle, two or more diffusers 10 can be connected in series. The diffuser 10 provided in the exemplary embodiment according to the figures has a convergent diffuser section 15 in the filament flow direction FS behind or below the secondary air inlet gaps 11, 12. At this convergent diffuser section 15 includes a constriction 16 of the diffuser 10 at. In the filament flow direction FS behind or under the constriction 16, the diffuser 10 is equipped with a divergent diffuser section 17. The divergent diffuser section 17 of the diffuser 10 is longer in the filament flow direction FS than the convergent diffuser section 15. The length I _{K of} the convergent diffuser section 15 is less than 50% of the length I _{D of} the divergent diffuser section 17.

Empfohlenermaßen and in the embodiment, the diffuser exit angle β between a diffuser wall 18 of the divergent diffuser section 17 and the longitudinal center axis M of the diffuser 10 is a maximum of 25 °. Expediently and in the exemplary embodiment, the width B of the diffuser outlet 19 is at most 300%, preferably at most 250%, of the width V _{B of} the exit slit 20 of the drawing shaft 9.

The continuous filaments 1 emerging from the diffuser 10 are deposited on a filing tray or nonwoven web 22 depositing device designed as a filing belt 21. The filament deposit or nonwoven web 22 is then conveyed away or transported away with the deposit cloth belt 21 in the machine direction MD. According to the invention, a suction device for Extraction of air or process air through the storage device or provided by the Ablagesiebband 21. For this purpose, a suction region 23 is arranged below the diffuser outlet 19, which has a width b in the machine direction (MD). This width b of the suction region 23 is greater according to the invention than the width B of the diffuser outlet 19. In the Fig. 2 the widths b and B are shown. According to a preferred embodiment of the invention, the width b of the suction region 23 is at least 1.2 times, preferably at least 1.3 times the width B of the diffuser exit 19. In the exemplary embodiment, the width B of the diffuser exit 19 is a horizontal distance of the lower ends the diffuser walls 18 measured. If the ends of the diffuser walls 18 of the divergent diffuser section 17 do not terminate in the same horizontal plane or at the same vertical height, preferably the distance of the end of the longer diffuser wall 18 from the end of the elongated shorter diffuser wall 18 is at the same vertical height measured.

The suction area 23 arranged below the storage belt 21 is delimited by two partitions 27, 28 arranged one behind the other in the machine direction MD. The width b of the suction region 23 is measured as a distance between the two partitions 27, 28, and in particular as a distance between the upper ends of the two partitions 27, 28. In particular from the Fig. 2 It can be seen that the suction region 23 with respect to the machine direction (MD) behind the storage area of the filaments 1 extends beyond a first suction section 24 via the diffuser exit 19 or across the width B of the diffuser exit 19. Furthermore, with respect to the machine direction (MD), the suction region 23 protrudes beyond the deposition region of the filaments 1 by a second suction section 25 beyond the diffuser exit 19 or across the width B of the diffuser exit 19. In the Fig. 2 It can be seen that the first suction section 24 has a width b ₁ and the second suction section 25 a Width b ₂ has. According to one embodiment and in the embodiment, the widths b ₁ and b _{2 are the} same size. In principle, however, they could also be designed differently.

In particular, due to the inventive design of the suction region 23, the suction is carried out by the Ablagesiebband 21 with the proviso that flows in the region of the diffuser outlet 19 tertiary air T along the outer surfaces 26 in the direction of Ablagesiebband 21. According to a particularly preferred embodiment, the streams of tertiary air T are aligned parallel or substantially parallel to the mixed flow of primary air P and secondary air S flowing in the direction of the diffuser outlet 19 of the diffuser 10. Thus, according to a very preferred embodiment of the invention by the Ablagesiebband 21 primary air P and secondary air S and tertiary air T is sucked. Expediently, the streams of primary air P, secondary air S and tertiary air T flow parallel or quasi parallel through the deposit screen belt 21.

Claims (8)

1. An apparatus for producing spunbonds from continuous filaments (1), in particular from thermoplastic material, comprising at least one spinneret (2) for spinning the continuous filaments (1), at least one cooling device (3) for cooling the filaments, at least one stretching device (7) for stretching the filaments, and at least one depositing device, in particular in the form of a depositing foraminous belt (21) for depositing the filaments to form a nonwoven web,
   wherein at least one diffuser (10) is arranged between the stretching device (7) and the depositing device or the depositing foraminous belt (21) so that filaments and primary air from the stretching device enter into the diffuser (10), wherein in the region of the at least one diffuser (10) at least two secondary air inlet gaps (11, 12) arranged on opposite sides of the diffuser (10) are provided, through which secondary air enters into the diffuser (10),
   wherein at least one secondary air inlet gap (11, 12), preferably at least two secondary air inlet gaps (11. 12) are formed with the proviso that the secondary air flows in at an inflow angle α with respect to the filament flow direction FS or with respect to the longitudinal central plane M of the apparatus or of the diffuser (10), wherein this inflow angle α is less than 100°, expediently less than or equal to 90°, preferably less than 80°, preferably less than 70° and particularly preferably less than 65°,
   wherein in the flow direction of the filaments downstream or below the secondary air inlet gaps (11, 12), a convergent diffuser section (15) follows,
   wherein in the flow direction of the filaments the convergent diffuser section (15) is followed by a constriction of the diffuser (10) and wherein the constriction is followed by at least one divergent diffuser section (17),
   wherein the convergent diffuser section (15) is designed to be shorter or significantly shorter than the divergent diffuser section (17) and wherein
   the length of the convergent diffuser section (15) is a maximum of 60% of the length of the divergent diffuser section (17),
   wherein the last diffuser section in the filament flow direction FS has diffuser walls (18) which diverge towards the depositing device, wherein these diffuser walls (18) form a diffuser outlet (19) having a width B in relation to the machine direction (MD),
   wherein at least one extraction device is provided to extract air or process air through the depositing device or through the depositing foraminous belt (21) and and wherein an extraction region (23) provided underneath the diffuser outlet (19) has a width b in the machine direction which width b is greater than the width B of the diffuser outlet (19).
2. The apparatus according to claim 1, wherein the width b of the extraction region (23) is at least 1.2 times, preferably at least 1.3 times and particularly preferably at least 1.4 times the width B of the diffuser outlet (19).
3. The apparatus according to one of claims 1 or 2, wherein the extraction region (23) projects relative to the machine direction (MD) downstream of the deposition region of the filaments by a (first) extraction section (24) beyond the diffuser outlet (19) and/or wherein the extraction region projects relative to the machine direction (MD) upstream of the deposition region of the filaments by a (second) extraction section (25) beyond the diffuser outlet (19).
4. The apparatus according to one of claims 1 to 3, wherein the extraction by the extraction device takes place such that at least in the region of the diffuser outlet (19) tertiary air flows along the outer surfaces of the diffuser walls (18) towards the deposition device or the depositing foraminous belt (21), wherein the tertiary air flows are preferably aligned parallel or substantially parallel to the mixed flow of primary air and secondary air flowing towards the diffuser outlet (19) inside the diffuser (10), and wherein the tertiary air is also extracted through the deposition device or through the depositing foraminous belt (21).
5. The apparatus according to one of claims 1 to 4, wherein the volume flow VT of tertiary air extracted with the extraction device is at least 25%, preferably at least 40% and particularly preferably at least 50% of the volume flow of the extracted primary and secondary air flows.
6. The apparatus according to one of claims 1 to 5, wherein the subassembly comprising the cooling device (3) and the stretching device (7) is configured as a closed subassembly such that apart from a supply of cooling air in the cooling device, no further fluid medium or air flows into this closed subassembly.
7. The apparatus according to one of claims 1 to 6, wherein the diffuser outlet angle β with respect to the longitudinal central axis M of the diffuser (10) is a maximum of 30°, preferably a maximum of 25°.
8. The apparatus according to one of claims 1 to 7, wherein the distance of the diffuser (10) or the lower edge of the diffuser (10) from the deposition device or the depositing foraminous belt (21) is 20 to 300 mm, in particular 30 to 150 mm and preferably 30 to 120 mm.

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