EP3575470B1 - Device for the manufacture of woven material from continuous filaments - Google Patents

Description

The invention relates to a device for the production of spunbonded nonwovens from continuous filaments, in particular from continuous filaments made of thermoplastic material, a spinnerette being provided for spinning the continuous filaments and a cooling chamber for cooling the spun filaments with cooling air, with one on opposite sides of the cooling chamber Air supply cabin is arranged and wherein cooling air can be introduced into the cooling chamber from the opposite air supply cabin, and flow straighteners are provided in the air supply cabin for rectifying the introduced cooling air. - Spunbond nonwoven in the context of the invention means in particular a spunbond nonwoven produced by the spunbond process. Because of their quasi-endless length, continuous filaments differ from staple fibers, which have much shorter lengths of, for example, 10 mm to 60 mm.

Devices of the type described above are known from practice in different embodiments. Many of these known devices have the disadvantage that the spunbonded nonwovens produced with them are not always sufficiently homogeneous over their surface area. Many spunbonded nonwovens produced therewith have disruptive inhomogeneities in the form of flaws or defects. The number of inhomogeneities generally increases with the throughput or with an increase in the thread speed. A typical flaw in such spunbonded fabrics is caused by so-called "drops". These are created by tearing off one or more soft or molten filaments, creating an accumulation of melt that causes a defect in the spunbonded nonwoven. Such defects are usually more than 2 mm in size 2 mm. - Defects in the spunbonded nonwovens can also be produced by so-called "hard pieces". These arise as follows: Due to the loss of tension, a filament can relax, snap back and form a tangle that creates the defect in the spunbonded surface. Such defects are usually smaller than 2 mm by 2 mm. Many spunbonded nonwovens or spunbond nonwovens produced by known processes have such inhomogeneities, especially when high throughputs are used in their production.

In contrast, the invention is based on the technical problem of specifying a device for producing spunbonded webs from continuous filaments with which very homogeneous spunbonded webs can be produced that are at least largely free of flaws or defects, in particular at higher throughputs of more than 200 kg / h / m and / or at high thread speeds.

To solve this technical problem, the invention teaches a device for the production of spunbonded nonwovens from continuous filaments - in particular from continuous filaments made of thermoplastic material - wherein a spinnerette is provided for spinning the continuous filaments, a cooling chamber for cooling the spun filaments with cooling air being provided, with an two opposite sides of the cooling chamber each have an air supply cabin, and cooling air can be introduced into the cooling chamber from the opposite air supply cabin,
wherein in at least one of the two air supply cabins, preferably in each of the two air supply cabins, at least one flow straightener is provided for rectifying the cooling air flow impinging on the filaments, one flow straightener having a plurality of transverse to the direction of movement the filaments or the filament stream has oriented flow channels, these flow channels being delimited by channel walls,
wherein the open area of a flow straightener is greater than 85%, preferably greater than 90% and wherein the ratio of the length L of the flow channels to the inner diameter D _{i of} the flow channels L / D _{i is} 1 to 15, preferably 1 to 10 and preferably 1.5 to 9 is.

It is recommended that the open area of a flow straightener is greater than 91%, preferably greater than 92% and particularly preferably greater than 92.5%. The open area of the flow straightener refers in particular to the free flow cross section of the flow straightener, which is not limited by the duct walls or the thickness of the duct walls and / or spacers possibly arranged between the flow ducts or the duct walls. In the calculation of this open area, in particular, no flow screens with their meshes that are arranged in the area of the flow straightener and above all are arranged in front of or behind the flow straightener. These flow screens or similar components are expediently disregarded when calculating the open area. It is recommended that the open area of a flow straightener is only calculated by adding up the open partial areas of all flow channels in relation to the total area of the flow straightener. The named open area and the total area of the flow straightener are arranged transversely, in particular perpendicular or essentially perpendicular to the flow channels and thus forms a cross-sectional area of the flow straightener.

D _{i means} the inside diameter of the flow channels. It thus becomes opposite for a flow channel starting from one channel wall Channel wall measured. If a flow channel has different diameters with regard to its cross section, D _{i means} in particular the smallest inside diameter of the flow channel. The smallest inner diameter D _i therefore relates here and below to the smallest inner diameter measured in a flow channel if this flow channel has different inner diameters with regard to its cross section. The smallest inside diameter of a cross-section in the form of a regular hexagon is measured between two opposite sides and not between two opposite corners. It is recommended that the ratio of the length L of the flow channels to the inner diameter D _{i of} the flow channels L / D _{i is} 2 to 8, preferably 2.5 to 7.5, preferably 2.5 to 7 and very preferably 3 to 6.5 . According to a particularly recommended embodiment, the ratio L / D _{i is} 4 to 6, in particular 4.5 to 5.5. If, with a plurality of flow channels, different lengths L of the flow channels and / or different inside diameters D _i or smallest inside diameter D _{i of} the flow channels should be present, L means the mean length and / or D _i the mean inside diameter or smallest inside diameter.

Machine direction (MD) means, here and below, the direction in which the filaments or the fleece deposit placed on a depositing device or on a depositing screen belt are / will be transported away. It is within the scope of the invention that the two air supply cabins or the flow straighteners extend transversely to the machine direction (CD direction) and that the cooling air is thus introduced essentially in the machine direction (MD) or counter to the machine direction.

With the flow straighteners according to the invention, a uniform, homogeneous flow of cooling air over the width of the system or in CD direction can be achieved. The invention is based on the knowledge that influencing the cooling or the cooling air flow in the cooling chamber and in particular the special design of the flow straighteners results in a very effective equalization of the filament deposition or fleece deposition. Due to the cooling according to the invention and in particular due to the design of the flow straightener, surprisingly homogeneous spunbonded nonwovens can be produced which are largely free of flaws or defects. This is especially true for higher throughputs and higher yarn speeds specified below.

It is within the scope of the invention that the cooling air supply for the cooling chamber takes place by sucking in the cooling air due to the filament movement or the downward filament flow and / or by actively blowing in or introducing cooling air, for example by means of at least one fan. The flow straighteners according to the invention are intended to effect a directed blowing on of the filaments, specifically expediently blowing transversely, preferably perpendicular to the filament axis or to the direction of flow of the filaments. It is also within the scope of the invention that the flow straighteners ensure a uniform or homogeneous flow of cooling air to the filaments. A homogeneous flow of cooling air onto the filaments here preferably means a homogeneous or uniform flow over the width of the device transversely to the machine direction, that is to say over the CD direction. The flow can differ fundamentally over the height of the cooling air chamber or the flow straightener. It is recommended that the flow straighteners according to the invention ensure, in particular, a uniform alignment of the air flow vectors, with the amount of the air velocity expediently remaining largely unchanged. The inventive design of A flow straightener in particular fulfills the above-described effect of a uniform or directed blowing of cooling air onto the filaments in the cooling chamber. According to a preferred embodiment, the same or essentially the same volume flows of cooling air are introduced into the cooling chamber from both opposite air supply cabins. In principle, however, it is also within the scope of the invention that different volume flows of cooling air are introduced into the cooling chamber from both air supply cabins.

A proven embodiment of the invention is characterized in that each air supply cabin is divided into at least two cabin sections, from which cooling air of different temperatures can be supplied. It is recommended that each air supply cabin has two cabin sections arranged one above the other or vertically one above the other, from which the cooling air of different temperatures is supplied. Cooling air of the same temperature is expediently introduced into the cooling chamber from two opposite cabin sections of two air supply cabins. According to a preferred embodiment of the invention, each air supply cabin is divided into only two cabin sections, from each of which cooling air of different temperatures can be supplied. According to another embodiment, an air supply cabin has three or more cabin sections from which cooling air of different temperatures can be introduced into the cooling chamber. - A flow straightener is preferably present in the area of each cabin section of the air supply cabin. A flow straightener expediently extends over all cabin sections of an air supply cabin. According to a preferred embodiment, a flow straightener extends over the entire height and / or width of the associated air supply cabin or essentially over the entire height and / or width of the associated air supply cabin.

A particularly recommended embodiment of the invention is characterized in that at least one flow straightener has at least one flow screen on its cooling air inflow side and / or on its cooling air outflow side. It is within the scope of the invention that a flow screen or the surface of a flow screen is arranged transversely and preferably perpendicular or substantially perpendicular to the longitudinal direction of the flow channels of a flow straightener. A flow straightener is recommended to have such a flow screen both on its cooling air inflow side and on its cooling air outflow side. A flow sieve is expediently tensioned or held or fastened under prestress on the cooling air inflow side and / or on the cooling air outflow side of a flow straightener. It is within the scope of the invention that a flow screen is arranged or rests directly on the flow straightener on the cooling air inflow side and / or on the cooling air outflow side of the flow straightener. The homogeneous flow onto the filaments with the cooling air should be supported with the preferably provided flow screens. - It is within the scope of the invention that when determining the open area of the flow straightener dealt with above and claimed in claim 1, the flow screens arranged in front of or behind the flow straightener are not taken into account.

It is recommended that a flow screen have a mesh size or an average mesh size of 0.1 to 0.5 mm, expediently from 0.1 to 0.4 mm and preferably from 0.15 to 0.34 mm. Mesh size means here in particular the distance between two opposing wires of the flow screen or the screen fabric of the flow screen. The mesh size is in particular the smallest distance of two opposite ones Wires of a mesh meant. If a flow screen has rectangular meshes with rectangular sides of different lengths, the mesh size means the distance between the two longer rectangular sides. A flow sieve is recommended to have a wire thickness or average wire thickness of 0.05 to 0.35 mm, preferably 0.05 to 0.32 mm, preferably 0.06 to 0.30 mm and very preferably 0.07 to 0 , 28 mm. It is within the scope of the invention that a flow screen has the same or the same size mesh or substantially the same or the same size mesh over its screen surface. Appropriately, there is a homogeneous distribution of meshes of the same geometry or of essentially the same geometry over the sieve surface.

According to a recommended embodiment of the invention, the open area of a flow screen is 15 to 55%, expediently 20 to 50% and preferably 25 to 45%. The open area of the flow screen means in particular the open area of the flow screen not occupied by the wire mesh and thus the area of the flow screen through which the cooling air can flow.

A preferred embodiment of the invention is characterized in that a flow straightener and a flow screen arranged on its cooling air inflow side and / or a flow screen arranged on its cooling air outflow side are accommodated in a common frame. This creates a solid or stable connection between the flow straightener and the flow sieves, which can be fixed as a whole in the air supply cabin. Preferably at least one such frame with a flow straightener and at least one flow screen is arranged on both opposite sides of the cooling chamber or on both air supply cabins.

According to the invention, the flow channels of the flow straightener or the flow straightener are arranged transversely to the direction of flow of the filaments and expediently transversely to the longitudinal center line M of the device. According to a preferred embodiment of the invention, the flow channels are oriented perpendicular or substantially perpendicular to the flow direction of the filaments or to the longitudinal center axis M of the device. It is within the scope of the invention that the flow channels are oriented perpendicular or essentially perpendicular to a plane oriented orthogonally to the machine direction (MD) or to a vertical plane running through the longitudinal center axis M of the device. In principle, however, it is also possible for the flow channels to be arranged at an angle to the planes mentioned. The angle of the oblique orientation of the flow channels of a flow straightener can be uniform or different. When the orientation or arrangement of the flow channels is mentioned here, this means in particular the orientation or arrangement of the longitudinal axes of the flow channels. It is within the scope of the invention that the flow channels of a flow straightener are linear or essentially linear.

A very preferred embodiment of the invention is characterized in that the flow channels of a flow straightener have a polygonal cross section, specifically preferably a square to octagonal cross section. A highly recommended embodiment of the invention is characterized in that the flow channels of a flow straightener are equipped with a hexagonal cross section. For this preferred case, the flow channels are thus designed as it were honeycomb.

According to a further preferred embodiment of the invention, the flow channels of a flow straightener have a round cross section, the flow channels preferably being designed with a circular or oval cross section. The circular cross section is preferred.

An additional embodiment of the invention is characterized in that the channel walls of the flow channels are wing-shaped or wing-shaped. The airfoil-shaped duct walls in particular exercise a directional function with regard to the cooling air flowing through. Rectangular or substantially rectangular flow channels are expediently formed between the wing-shaped or airfoil-shaped channel walls. It is within the scope of the invention that the smallest distance between two adjacent wing-shaped or airfoil-shaped duct walls is 2 to 15 mm, preferably 3 to 12 mm and preferably 5 to 10 mm.

A highly recommended embodiment of the invention is characterized in that the inner surface of a flow straightener through which the cooling air flows is 5 to 50 m ² , preferably 7.5 to 45 m ² and preferably 10 to 40 m ² per square meter of flow cross section of the flow straightener. The inner surface through which the cooling air flows is calculated from the sum of the surfaces of the duct walls of the flow ducts through or against which flow per square meter of flow cross section of the flow straightener. It is within the scope of the invention that the flow sieves of the flow straightener are not taken into account when calculating this inner surface through which flow occurs.

According to a very preferred embodiment of the invention, the length L of the flow channels of a flow straightener is 15 to 65 mm, preferably 20 to 60 mm, preferably 20 to 55 mm and very preferably 25 to 50 mm. The inside diameter or the smallest inside diameter D _{i of} the flow channels is recommended to be 2 to 15 mm, preferably 3 to 12 mm, preferably 4 to 11 mm and very preferably 5 to 10 mm. - It is within the scope of the invention that the flow channels in a flow straightener are arranged compact and close to one another. In a flow straightener, flow channel preferably adjoins flow channel and, according to one embodiment, only spacers can be present between the flow channels. The mutual spacing of the flow channels or at least the majority of the flow channels is recommended to be smaller or significantly smaller than the smallest inner diameter D _{i of} a flow channel. The flow channels are expediently arranged in a flow straightener according to the principle of the closest packing.

It is within the scope of the invention that at least one supply line for supplying the cooling air with a cross-sectional area Qz is connected to each air supply cabin, this cross-sectional area Qz of the supply line increasing to a cross-sectional area Q _{L of} the air supply cabin when the cooling air passes into the supply cabin, whereby the cross-sectional area Q _{L is} at least twice as large, preferably at least three times as large and preferably at least four times as large as the cross-sectional area Qz of the supply line. The cross-sectional area Qz of the supply line expediently expands to 3 to 15 times the cross-sectional area Q _{L of} the air supply cabin. According to one embodiment of the invention, the cooling volume flow supplied to an air supply cabin is divided into a plurality of partial volume flows, which partial volume flows flow through separate partial supply lines and / or through the segments of a segmented supply line. The cooling air volume flow can in particular be divided into two to five, preferably two to three partial volume flows. If each partial volume flow flows in through a separate partial supply line, the cross-sectional area Q _{Z of} the partial supply line expands to the cross-sectional area Q _{L of} the relevant cabin section of the air supply cabin. In this case, the cross-sectional area Q _{L is} preferably at least twice as large, preferably at least three times as large as the cross-sectional area Q _{Z of} the partial feed line. It is recommended that the cross-sectional area Q _{Z of} a supply line or a partial supply line expand in steps - in particular in several stages - or continuously to the cross-sectional area Q _{L of} the air supply cabin or to the cross-sectional area of a cabin section of the air supply cabin.

According to a particularly recommended embodiment of the invention, at least one flat homogenizing element for homogenizing the cooling air flow introduced into the air supply cabin is arranged in the air supply cabin in the flow direction of the cooling air upstream of the flow straightener and at a distance from the flow straightener. It is within the scope of the invention that a flat homogenization element has a plurality of openings and that the free open area of the flat homogenization element is 1 to 20%, preferably 2 to 18% and preferably 2 to 15% of the total area of the flat homogenization element. According to one embodiment, at least one homogenization element is designed as a perforated element, in particular as a perforated plate, with a plurality of perforated openings, the perforated openings preferably having an opening diameter of 1 to 10 mm, preferably 1.5 to 9 mm and very preferably 1.5 to 8 mm. According to another preferred embodiment of the invention, a homogenizing element is designed as a homogenizing sieve with a plurality or with a plurality of meshes, the homogenizing sieve preferably Mesh sizes from 0.1 to 0.5 mm, preferably from 0.12 to 0.4 mm and very preferably from 0.15 to 0.35 mm. It is recommended that the at least one flat homogenization element is arranged at a distance a ₁ of at least 50 mm, preferably of at least 80 mm and preferably of at least 100 mm in the flow direction of the cooling air in front of the flow straightener of the corresponding air supply cabin or in front of the flow screen of this flow straightener . A plurality of homogenizing elements are expediently arranged at a distance from the flow straightener in the flow direction of the cooling air one behind the other and at a distance from one another in an air supply cabin. The distance between two homogenizing elements arranged one behind the other in an air supply cabin in the direction of flow is at least 50 mm, preferably at least 80 mm and preferably at least 100 mm.

In the device according to the invention, the continuous filaments are spun out by means of a spinnerette and fed to the cooling chamber with the air supply cabins and flow straighteners. It is within the scope of the invention that at least one spinning beam for spinning the filaments is arranged transversely to the machine direction (MD direction). According to a very preferred embodiment of the invention, the spinning beam is oriented perpendicular or essentially perpendicular to the machine direction. However, within the scope of the invention it is also possible for the spinning beam to be arranged at an angle to the machine direction. According to a very preferred embodiment of the invention, at least one monomer suction device is provided between the spinnerette or the spinning beam and the cooling chamber. With the monomer suction device, air is sucked out of the filament formation space below the spinnerette. In this way, the gases such as monomers, oligomers, decomposition products and the like that escape in addition to the continuous filaments can be removed from the device according to the invention. A The monomer suction device expediently has at least one suction chamber to which at least one suction fan is preferably connected. It is recommended that the cooling chamber according to the invention with the air supply cabins and flow straighteners adjoin the monomer suction device in the direction of flow of the filaments.

It is within the scope of the invention that the filaments are introduced from the cooling chamber into a drawing device for drawing the filaments. Appropriately, the cooling chamber is followed by an intermediate channel which connects the cooling chamber with a stretching shaft of the stretching device.

According to a particularly preferred embodiment of the invention, the unit from the cooling chamber and the stretching device or the unit from the cooling chamber, the intermediate channel and the stretching shaft is designed as a closed system. In this context, a closed system means in particular that, apart from the supply of cooling air into the cooling chamber, no further air is supplied to this unit. The flow straighteners used according to the invention are distinguished above all by special advantages in such a closed system. A particularly simple and effective equalization of the air flow or cooling air flow is possible here.

At least one diffuser preferably adjoins the stretching device in the direction of flow of the filaments, the filaments being guided through this diffuser. It is recommended that the diffuser comprises a diffuser cross-section or a divergent diffuser section that widens in the direction in which the filaments are deposited. It is within the scope of the invention that the filaments are deposited on a depositing device for filament depositing or for depositing fleece. The storage device is expediently around a storage screen belt or around an air-permeable storage screen belt. The nonwoven web formed from the filaments is conveyed away in the machine direction (MD) with the depositing device or with the depositing screen belt.

According to a preferred embodiment of the invention, process air is sucked through the depositing device or through the depositing screen belt or sucked in from below, at least in the deposit area of the filaments. A particularly stable filament deposit or fleece deposit is achieved in this way. This suction is of advantageous importance within the scope of the invention in combination with the flow straighteners according to the invention. - After being deposited on the depositing device, the nonwoven web is expediently fed to further treatment measures, in particular calendering.

It is within the scope of the invention that the device according to the invention is designed or set up with the proviso that it is possible to work with thread speeds or filament speeds above 2000 m / min, in particular with thread speeds above 2200 m / min or above 2500 m / min , for example with a thread speed in the range of 3000 m / min. These filament speeds can be used in the context of the production of filaments or spunbonded nonwovens from polyolefins, in particular from polypropylene. In the course of the production of filaments or spunbonded nonwovens from polyesters, in particular from polyethylene terephthalate (PET), thread speeds or filament speeds of over 4000 m / min and even over 5000 m / min can be achieved with the device according to the invention. For the high thread speeds listed above - both with regard to polyolefins and with regard to polyester - the configuration of the air supply cabins with the flow straighteners according to the invention has proven particularly useful. The invention is based on the knowledge that with the device according to the invention, spunbonded nonwovens of optimum quality and, above all, with homogeneous properties can be achieved over their surface area. Defects or defects in the webs or in the web surfaces can be completely prevented or at least largely minimized. These advantages can in particular also be achieved with high throughputs of the device of more than 150 kg / h / m or more than 200 kg / h / m. Due to the design of the air supply cabins or the flow straightener according to the invention, an optimal supply of cooling air into the cooling chamber is ensured, which ultimately leads to the advantageous properties of the spunbonded nonwoven web. Within the scope of the invention, a very uniform or homogeneous supply of cooling air can be implemented, and because of this advantageous supply of cooling air, the filaments are positively influenced to the extent that undesired defects in the nonwoven web can be prevented or largely minimized. The device according to the invention can nonetheless be implemented with relatively simple and inexpensive measures. It is therefore also characterized by its low cost.

Fig. 1

einen Vertikalschnitt durch die erfindungsgemäße Vorrichtung,

Fig. 2

einen vergrößerten Ausschnitt aus der Fig. 1 mit der Kühlvorrichtung aus der Kühlkammer und den Luftzufuhrkabinen,

Fig. 3

eine perspektivische Ansicht eines Aggregates aus einem Strömungsgleichrichter mit vor- und nachgeschaltetem Strömungssieb,

Fig. 4

einen Querschnitt durch einen Strömungsgleichrichterabschnitt mit im Querschnitt sechseckförmigen bzw. wabenförmigen Strömungskanälen,

Fig. 5

den Gegenstand nach Fig. 4 mit im Querschnitt kreisrunden Strömungskanälen und

Fig. 6

den Gegenstand gemäß Fig. 4 mit tragflügelförmigen Kanalwandungen der Strömungskanäle des Strömungsgleichrichters.

The invention is explained in more detail below with reference to a drawing showing only one embodiment. It shows in a schematic representation:

Fig. 1

a vertical section through the device according to the invention,

Fig. 2

an enlarged section from the Fig. 1 with the cooling device from the cooling chamber and the air supply cabins,

Fig. 3

a perspective view of an assembly consisting of a flow straightener with upstream and downstream flow screen,

Fig. 4

a cross section through a flow straightener section with hexagonal or honeycomb flow channels in cross section,

Fig. 5

the subject Fig. 4 with circular cross-section flow channels and

Fig. 6

the subject according to Fig. 4 with airfoil-shaped channel walls of the flow channels of the flow straightener.

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 comprises a spinnerette 2 for spinning the endless filaments 1. These spun endless filaments 1 are introduced into a cooling device 3 with a cooling chamber 4 and with air supply cabins 5, 6 arranged on two opposite sides of the cooling chamber 4. The cooling chamber 4 and the air supply cabins 5, 6 extend transversely to the machine direction MD and thus in the CD direction of the device. Cooling air is introduced into the cooling chamber 4 from the opposite air supply cabins 5, 6. A monomer suction device 7 is preferably arranged between the spinnerette 2 and the cooling device 3 and in the exemplary embodiment. With this monomer suction device 7 interfering gases occurring during the spinning process can be removed from the device. These gases can be, for example, monomers, oligomers or decomposition products and similar substances.

In the filament flow direction FS, the cooling device 3 is followed by a drawing device 8 in which the filaments 1 are drawn. The stretching device 8 preferably and in the exemplary embodiment has an intermediate channel 9 which connects the cooling device 3 to a stretching shaft 10 of the stretching device 8. According to a particularly preferred embodiment and in the exemplary embodiment, the unit from the cooling device 3 and the stretching device 8 or the unit from the cooling device 3, the intermediate channel 9 and the stretching shaft 10 is designed as a closed system. A closed system means that apart from the supply of cooling air in the cooling device 3, no further air is supplied to this unit.

Appropriately and in the exemplary embodiment, a diffuser 11, through which the filaments 1 are guided, adjoins the stretching device 8 in the filament flow direction FS. According to one embodiment and in the exemplary embodiment, secondary air inlet gaps 12 for introducing secondary air into the diffuser 11 are provided between the stretching device 8 or between the stretching shaft 10 and the diffuser 11. After passing through the diffuser 11, the filaments 1 are preferably and in the exemplary embodiment deposited on a depositing device designed as a depositing screen belt 13. The filament deposit or the nonwoven web 14 is then expediently conveyed or transported away in the machine direction MD, and in the exemplary embodiment with the depositing screen belt 13. Recommended and in the exemplary embodiment, a suction device is provided under the depositing device or below the depositing screen belt 13 for sucking off air or process air through the depositing device or through the depositing screen belt 13. For this purpose, a suction area 15 is preferred and arranged in the exemplary embodiment below the diffuser outlet under the screen belt 13. Appropriately and in the exemplary embodiment, the extends Suction area 15 at least over the width B of the diffuser outlet. Preferably, and in the exemplary embodiment, the width b of the suction area 15 is greater than the width B of the diffuser outlet.

According to the preferred embodiment and in the exemplary embodiment, each air supply cabin 5, 6 is divided into two cabin sections 16, 17 from which cooling air of different temperatures can be supplied. Thus, preferably and in the embodiment of the upper cabin sections 16 each cooling air having a temperature T ₁ can be fed while from the two lower portions 17 each cabin cooling air a direction different from the temperature T ₁ Temperature T can be fed to _{the second} According to one embodiment and in the embodiment, a flow straightener 18 is arranged in each air supply cabin 5, 6 on the cooling chamber side, which flow straightener preferably extends over both cabin sections 16, 17 of each air supply cabin 5, 6 in the embodiment.

The two flow straighteners 18 serve to straighten the cooling air flow impinging on the filaments 1. In this case, and in the exemplary embodiment, each flow straightener 18 preferably has a plurality of flow channels 19 oriented perpendicular to the filament flow direction FS. These flow channels 19 are each delimited by channel walls 20 and are preferably linear.

According to the preferred embodiment and in the exemplary embodiment, the open area of each flow straightener 18 is more than 90% of the total area of the flow straightener 18. Recommended and in the exemplary embodiment, the ratio of the length L of the flow channels 19 to the smallest inner diameter D _{i of} the flow channels 19 is in the range between 1 and 10, expediently in the range between 1 and 9.

According to the very well-proven embodiment and in the embodiment, each flow straightener 18 has a flow screen 21 both on its cooling air inflow side ES and on its cooling air outflow side AS. Preferably, and in the exemplary embodiment, the two flow screens 21 of each flow straightener 18 are arranged directly in front of or behind the flow straightener 18.

Recommended and in the exemplary embodiment, the two flow screens 21 of a flow straightener 18 or the surfaces of these flow screens 21 are oriented perpendicular to the longitudinal direction of the flow channels 19 of the flow straightener 18. It has been proven that a flow screen 21 has a mesh size w of 0.1 to 0.5 mm, preferably 0.1 to 0.4 mm and preferably 0.15 to 0.34 mm. Furthermore, it is advantageous if the flow screen has a wire thickness d of 0.05 to 0.35 mm, preferably 0.05 to 0.32 mm and preferably 0.07 to 0.28 mm. It is within the scope of the invention that the mesh size w of the flow screens 21 is significantly smaller than the smallest inner diameter D _{i of} the flow channels 19 of the flow straightener 18. The mesh size w of a flow screen 21 is preferably less than 1/6, very preferably less than 1 / 8 and particularly preferably less than 1/10 of the smallest inner diameter D _{i of} the flow channels 19. The open area of a flow screen 21 that is not occupied by wire is recommended to be 21 to 50% and preferably 25 to 45% of the total area of a flow screen 21.

The Figures 4 to 6 show typical cross sections of the flow channels 19 of a flow straightener 18 used according to the invention. According to a recommended embodiment and in the embodiment according to FIG Fig. 4 the flow channels 19 of a flow straightener 18 have a hexagonal or honeycomb-shaped cross section. The smallest inner diameter D _i is measured here between opposite sides of the hexagon (see Fig. Fig. 4 ). - In the embodiment according to Fig. 5 the flow channels 19 of the flow straightener 18 have a circular cross section. - The Fig. 6 shows an embodiment of a flow straightener 18 according to the invention with airfoil-shaped channel walls 20. These airfoil-shaped channel walls 20 are expediently separated from one another in the exemplary embodiment by spacers 22, which spacers 22 also form channel walls of these flow channels. The airfoil-shaped duct walls 20 are curved in cross section (see right side of FIG Fig. 6 ). In principle, the airfoil-shaped duct walls 20 can also be designed in a straight line and in this case the flow straightener 18 is designed like a grating.

Claims (15)

1. Apparatus for manufacturing spunbonded nonwovens from continuous filaments (1), in particular from continuous filaments (1) of thermoplastic material, wherein a spinneret (2) is provided for spinning out the continuous filaments (1) and wherein a cooling chamber (4) is provided for cooling the spun-out filaments (1) with cooling air, wherein respectively one air supply manifold (5, 6) is arranged on two opposite sides of the cooling chamber (4) and wherein cooling air can be introduced into the cooling chamber (4) from the opposite air supply manifolds (5, 6), wherein in each of the two air supply manifolds (5, 6) respectively at least one flow straightener (18) is provided for rectifying the cooling air flow impinging upon the filaments (1), wherein a flow straightener (18) comprises a plurality of flow channels (19) oriented transversely to the direction of movement of the filaments (1) or the filament flow, wherein the flow channels (19) are delimited by channel walls (20),
   wherein the open area of a flow straightener (18) is greater than 85%, preferably greater than 90% and wherein the ratio of the length L of the flow channels (19) to the diameter D_i of the flow channels (19) L/D_i is 1 to 15, preferably 1 to 10 and preferably 1.5 to 9.
2. Apparatus according to Claim 1, wherein a monomer extraction device (7) is disposed between spinneret (2) and cooling chamber (4).
3. Apparatus according to one of Claims 1 or 2, wherein each air supply manifold (5, 6) is divided into at least two, preferably into two manifold sections (16, 17) from which cooling air at different temperature can be supplied in each case.
4. Apparatus according to one of Claims 1 to 3, wherein at least one flow straightener (18) has at least one flow screen (21) on its cooling air inflow side ES and/or on its cooling air outflow side AS, wherein the flow screen (21) is preferably arranged transversely, preferably perpendicularly to the longitudinal direction of the flow channels (19).
5. Apparatus according to Claim 4, wherein the at least one flow screen (21) has a mesh width of 0.1 to 0.4 mm, preferably of 0.15 to 0.34 mm and wherein the at least one flow screen (21) preferably has a wire thickness of 0.05 to 0.32 mm, preferably of 0.07 to 0.28 mm.
6. Apparatus according to one of Claims 4 or 5, wherein the open area of the at least one flow screen (21) is 20 to 50%, preferably 25 to 45%.
7. Apparatus according to one of Claims 1 to 6, wherein the open area of a flow straightener (18) is greater than 91%, preferably greater than 92%.
8. Apparatus according to one of Claims 1 to 7, wherein the ratio L/D_i is 2 to 8, preferably 2.5 to 7.5, preferably 2.5 to 7 and very preferably 3 to 6.5.
9. Apparatus according to one of Claims 1 to 8, wherein the flow channels (19) of a flow straightener (18) have a polygonal cross-section, preferably a quadrangular to octagonal cross-section and particularly preferably a hexagonal cross-section.
10. Apparatus according to one of Claims 1 to 9, wherein the flow channels (19) of a flow straightener (18) have a round cross-section, preferably a circular or oval cross-section.
11. Apparatus according to one of Claims 1 to 8, wherein the channel walls (20) of the flow channels (19) are configured to be wing-shaped or aerofoil-shaped and wherein preferably the spacing between two adjacent wing-shaped channel walls (20) is 3 to 12 mm, preferably 5 to 10 mm.
12. Apparatus according to one of Claims 1 to 11, wherein the inner surface of a flow straightener (18) through which the cooling air flows is 5 to 50 m², preferably 7.5 to 45 m² and preferably 10 to 40 m² per m² of flow cross-section of the flow straightener (18).
13. Apparatus according to one of Claims 1 to 12, wherein the length L of the flow channels (19) of the flow straightener (18) is 15 to 65 mm, preferably 20 to 60 mm, preferably 20 to 55 mm and very preferably 25 to 50 mm.
14. Apparatus according to one of Claims 1 to 13, wherein the internal diameter D_i or the smallest internal diameter D_i of the flow channels (19) is 2 to 15 mm, preferably 3 to 12 mm, preferably 4 to 11 mm and very preferably 5 to 10 mm.
15. Apparatus according to one of Claims 1 to 14, wherein the apparatus is designed with the proviso that the filaments (1) flow through the apparatus at a filament speed greater than 2000 m/min, preferably greater than 2200 m/min or flow through the apparatus at a filament speed greater than 4000 m/min, in particular greater than 5000 m/min.

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