阅读说明：本技术 用于由连续长丝制造纺粘型非织造织物的设备 (Apparatus for producing spunbonded nonwoven fabrics from continuous filaments ) 是由 M·尼奇克 M·诺伊恩霍费尔 H－G·戈伊斯 D·弗赖 T·克雷奇曼 于 2019-05-28 设计创作，主要内容包括：用于由连续长丝制造纺粘型非织造织物的设备,其中,设置有用于纺出连续长丝的纺丝头并且设有用于利用冷却空气冷却长丝的冷却室。在所述冷却室的两个相对置的侧上分别设置有一个空气供给室,并且冷却空气可以从所述相对置的空气供给室中被引导到冷却室中。在所述两个空气供给室中的每个空气供给室中分别设置有至少一个用于整流遇到长丝的冷却空气流的流动整流器。流动整流器具有多个横向于长丝的运动方向定向的流动通道。流动整流器的通流面积大于85％并且流动通道的长度L与流动通道的直径D<Sub>i</Sub>的比值L/D<Sub>i</Sub>为1至15。(An apparatus for producing a spunbonded nonwoven fabric from continuous filaments, wherein a spinning head for spinning the continuous filaments is provided and a cooling chamber for cooling the filaments with cooling air is provided. One air supply chamber is provided on each of two opposite sides of the cooling chamber, and cooling air can be conducted from the opposite air supply chambers into the cooling chamber. At least one flow straightener is provided in each of the two air supply chambers for straightening the cooling air flow that encounters the thread. The flow straightener has a plurality of flow channels oriented transverse to the direction of movement of the filaments. The flow area of the flow straightener is greater than 85% and the ratio L/Di of the length L of the flow channel to the diameter Di of the flow channel is 1 to 15.)

1. An apparatus for producing a spunbonded nonwoven fabric from continuous filaments (1), in particular from continuous filaments (1) made of thermoplastic, wherein a spinneret (2) is provided for spinning the continuous filaments (1) and a cooling chamber (4) is present for cooling the spun filaments (1) with cooling air, wherein one air supply chamber (5, 6) is provided on each of two opposite sides of the cooling chamber (4) and cooling air can be introduced into the cooling chamber (4) from the respective air supply chamber (5, 6) lying opposite one another,

Wherein in each of the two air supply chambers (5, 6) at least one flow straightener (18) is provided for straightening a cooling air flow which encounters the thread (1), wherein the flow straightener (18) has a plurality of flow channels (19) which are oriented transversely to the direction of movement of the thread (1) or the thread flow, wherein the flow channels (19) are delimited by channel walls (20),

Wherein the flow area of the flow straightener (18) is more than 85%, preferably more than 90%, and the ratio L/Di of the length L of the flow channel (19) to the inner diameter Di of the flow channel (19) is from 1 to 15, preferably from 1 to 10 and more preferably from 1.5 to 9.

2. the apparatus according to claim 1, characterized in that a monomer suction device (7) is provided between the spinning head (2) and the cooling chamber (4).

3. The apparatus according to claim 1 or 2, characterized in that each air supply chamber (5, 6) is divided into at least two, preferably two, chamber sections (16, 17), from which cooling air of different temperatures can be supplied, respectively.

4. The apparatus according to any of claims 1 to 3, characterized in that 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, and preferably the flow screen (21) is arranged transverse, more preferably perpendicular, to the longitudinal direction of the flow channel (19).

5. The apparatus according to claim 4, characterized in that the at least one flow screen (21) has a mesh width of 0.1mm to 0.4mm, preferably 0.15mm to 0.34mm, and the at least one flow screen (21) preferably has a wire thickness of 0.05mm to 0.32mm, more preferably 0.07mm to 0.28 mm.

6. The apparatus according to claim 4 or 5, characterized in that the flow area of the at least one flow screen (21) is 20 to 50%, preferably 25 to 45%.

7. The apparatus according to any of claims 1 to 6, characterized in that the flow area of the flow straightener (18) is larger than 91%, preferably larger than 92%.

8. the apparatus according to any one of claims 1 to 7, characterized in that the ratio L/Di is from 2 to 8, preferably from 2.5 to 7.5, preferably from 2.5 to 7 and very preferably from 3 to 6.5.

9. The device according to any of claims 1 to 8, characterized in that the flow channels (19) of the flow straightener (18) have a polygonal cross section, preferably a quadrangular to octagonal cross section and very preferably a hexagonal cross section.

10. The apparatus according to any of claims 1 to 9, characterized in that the flow channel (19) of the flow rectifier (18) has a rounded cross-section, preferably a circular cross-section or an elliptical cross-section.

11. device according to one of claims 1 to 8, characterized in that the channel walls (20) of the flow channel (19) are configured in the shape of an airfoil or a wing, and preferably the distance between two adjacent airfoil-shaped channel walls (20) is 3mm to 12mm, preferably 5mm to 10 mm.

12. The apparatus according to one of claims 1 to 11, characterized in that the inner area of the flow rectifier (18) traversed by the cooling air is 5m2 to 50m2, preferably 7.5m2 to 45m2 and particularly preferably 10m2 to 40m2 per square meter of the flow cross section of the flow rectifier (18).

13. The apparatus according to any of claims 1 to 12, characterized in that the length L of the flow channel (19) of the flow straightener (18) is 15 to 65mm, preferably 20 to 60mm, more preferably 20 to 55mm and very preferably 25 to 50 mm.

14. the apparatus as claimed in any of claims 1 or 13, characterised in that the inner diameter Di or the smallest inner diameter Di of the flow channel (19) is 2mm to 15mm, preferably 3mm to 12mm, more preferably 4mm to 11mm and very preferably 5mm to 10 mm.

15. The apparatus according to any of claims 1 to 14, characterized in that the apparatus is designed such that the filaments (1) flow through the apparatus at a yarn speed of more than 2000m/min, preferably more than 2200m/min, or at a yarn speed of more than 4000m/min, in particular more than 5000 m/min.

Technical Field

The invention relates to a device for producing a spunbonded nonwoven fabric from continuous filaments, in particular from continuous filaments made of thermoplastic, wherein a spinneret for spinning out the continuous filaments is provided and a cooling chamber for cooling the spun-out continuous filaments with cooling air is provided, wherein one air supply chamber is provided on each of the opposite sides of the cooling chamber, and cooling air can be introduced into the cooling chamber from the opposite air supply chambers and a flow rectifier for rectifying the introduced cooling air is provided in the air supply chamber. Spunbonded nonwoven fabrics are in the context of the present invention particularly spunbonded nonwovens produced according to the spunbonding process. Continuous filaments differ from much shorter staple fibers having a length of, for example, 10mm to 60mm, due to their length, which can be said to be infinitely long.

Background

Devices of the type mentioned above are known in practice in principle in different embodiments. Many of the known devices have the following disadvantages: spunbond nonwoven fabrics produced in this manner are not always sufficiently uniform in their surface extension. Many spunbond nonwoven fabrics produced therewith have disturbing inhomogeneities in the form of defects or defects. The amount of said unevenness generally increases with production capacity or with increasing yarn speed. The typical defects in such spunbond nonwoven fabrics are produced by so-called "droplets". The droplets are caused by the breaking of one or more soft or molten filaments, thereby creating melt buildup that causes defects in the spunbond nonwoven fabric. Such defects typically have a size greater than 2mm x 2 mm. Defects in spunbond nonwoven fabrics can also be caused by so-called "stiff sheets". The defects are generated as follows: the filaments may relax through stress loss, snap back and form balls that create points of weakness in the surface of the spunbond nonwoven. Such defects are typically less than 2mm by 2 mm. Many spunbond nonwoven fabrics or spunbond nonwoven fabrics produced according to the known methods have such inhomogeneities, in particular when working at high throughput in their production.

Disclosure of Invention

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

In order to solve the problem, the invention teaches an apparatus for producing a spunbonded nonwoven from continuous filaments, in particular from continuous filaments made of thermoplastic, wherein a spinning head is provided for spinning the continuous filaments, a cooling chamber is provided for cooling the spun continuous filaments with cooling air, wherein one air supply chamber is provided on each of two opposite sides of the cooling chamber and cooling air can be introduced into the cooling chamber from the opposite air supply chambers,

Wherein at least one flow straightener for straightening the cooling air flow which encounters the thread is provided in at least one of the two air supply chambers, preferably in each of the two air supply chambers, wherein the flow straightener has a plurality of flow channels which are oriented transversely to the direction of movement of the thread or thread flow, wherein the flow channels are delimited by channel walls,

Wherein the flow area of the flow straightener is more than 85%, preferably more than 90%, and the ratio L/Di of the length L of the flow channel to the inner diameter Di of the flow channel is 1 to 15, preferably 1 to 10 and preferably 1.5 to 9.

It is recommended that the flow area of the flow straightener is greater than 91%, preferably greater than 92% and particularly preferably greater than 92.5%. The flow area of the flow straightener is in particular the free flow cross section of the flow straightener, which is therefore not limited by the channel walls or the thickness of the channel walls and/or spacers which may be arranged between the individual flow channels or between the individual channel walls. In particular, a flow screen arranged in the region of the flow straightener and in particular upstream or downstream of the flow straightener, which flow screen has its mesh, is not taken into account when calculating the flow area. Advantageously, the flow screen or similar component is not considered in the calculation of the flow area. It is recommended that the flow area of the flow straightener is only obtained by the sum of the ratio of the partial area of all flow channels through which flow can flow to the total area of the flow straightener. The flow area and the total area of the flow straightener are arranged transversely, in particular perpendicularly or substantially perpendicularly, to the flow channel and thus form the cross-sectional area of the flow straightener.

Di refers to the inner diameter of the flow channel. The inner diameter is therefore measured for the flow channel starting from one channel wall to the opposite channel wall. Di especially refers to the smallest inner diameter of the flow channel when the flow channel has different diameters with respect to its cross section. Thus, when the flow channel has different inner diameters with respect to its cross section, said minimum inner diameter Di is referred to here and in the following as the minimum inner diameter measured in the flow channel. The minimum inner diameter is therefore measured in a cross section in the form of a regular hexagon between two opposite sides and not between two opposite corners. It is recommended that the ratio L/Di of the length L of the flow channel to the inner diameter Di of the flow channel 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 preferred embodiment, the ratio L/Di is 4 to 6, in particular 4.5 to 5.5. When different lengths L of the flow channels and/or different inner diameters Di or minimum inner diameters Di of the flow channels should be present in a plurality of flow channels, L refers to the average length and/or Di refers to the average or minimum inner diameter.

The Machine Direction (MD) is here and in the following the direction in which the laid layers of filaments or nonwoven laid on the laying device or the laying screen belt are transported away. Within the scope of the invention, the two air supply chambers or flow straighteners extend transversely to the machine direction (CD direction) and the cooling air is therefore introduced essentially in the Machine Direction (MD) or counter to the machine direction.

With the flow straightener according to the invention, in particular, a uniform inflow of cooling air over the width or in the CD direction of the installation can be achieved. The invention is based on the recognition that: the very effective homogenization of the laying of the filaments or of the nonwoven fabric is brought about by the effect exerted on the cooling or cooling air flow in the cooling chamber and in particular by the special configuration of the flow straightener. Based on the cooling according to the invention and in particular on the configuration of the flow straightener, an unexpectedly homogeneous spunbond nonwoven can be produced which is largely defect-free or defect-free. This also applies in particular to higher production capacities and higher thread speeds which are subsequently described further below.

Within the scope of the invention, the supply of cooling air for the cooling chamber is effected by sucking in cooling air on the basis of the movement of the filaments or the downwardly directed flow of the filaments and/or by actively blowing in or introducing cooling air, for example by means of at least one fan. The flow straightener according to the invention is intended to facilitate the directional blowing in of the filaments, more precisely advantageously transversely, preferably perpendicularly, to the axis of the filaments or perpendicularly to the direction of flow of the filaments. Furthermore, within the scope of the invention, the flow straightener ensures a uniform or homogeneous inflow of cooling air to the filaments. A uniform cooling air inflow of the filaments here preferably means a uniform and homogeneous inflow over the width of the apparatus transverse to the machine direction, i.e. in the CD direction. The inflow can in principle be different at the height of the cooling air chamber or the flow straightener. It is recommended that the flow straightener according to the invention especially ensures a uniform orientation of the air flow vector, wherein advantageously the value of the air velocity remains largely unchanged. The configuration according to the invention of the flow straightener achieves in particular the effect of a uniform or directed blowing of the filaments with cooling air in the cooling chamber. According to a preferred embodiment, identical or substantially identical cooling air volume flows are introduced into the cooling chamber from two opposite air supply chambers. However, it is also in principle within the scope of the invention to introduce cooling air from two air supply chambers into the cooling chamber in different volumetric flows.

A proven embodiment of the invention is characterized in that each air supply chamber is divided into at least two chamber sections, from which cooling air at different temperatures can be supplied in each case. It is recommended here that each air supply chamber has two chamber sections arranged one above the other or vertically above the other, from which cooling air of different temperatures is supplied. Advantageously, cooling air of the same temperature is introduced into the cooling chamber from two opposite chamber sections of the two air supply chambers. According to a preferred embodiment of the invention, each air supply chamber is divided into only two chamber sections from which cooling air at different temperatures can be supplied in each case. According to a further embodiment, the air supply chamber has three or more chamber sections, from which cooling air of different temperatures can be introduced into the cooling chamber. Preferably, a flow rectifier is present in the region of each chamber section of the air supply chamber. Advantageously, a flow straightener extends over all chamber sections of an air supply chamber. According to a preferred embodiment, the flow straightener extends over the entire height and/or width of the associated air supply chamber or substantially over the entire height and/or width of the associated air supply chamber.

A particularly preferred embodiment of the invention is characterized in that the 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. In this context, it is within the scope of the invention for the surface of the flow screen or of the flow screen to be arranged transversely and preferably perpendicularly or substantially perpendicularly to the longitudinal direction of the flow channel of the flow straightener. It is recommended that the flow straightener have such a flow screen both on its cooling air inflow side and on its cooling air outflow side. The flow screen is advantageously held or fixed under tension or with pretension on the cooling air inflow side and/or on the cooling air outflow side of the flow straightener. Within the scope of the invention, the flow screen is arranged directly on or in contact with the flow straightener on the cooling air inflow side and/or on the cooling air outflow side of the flow straightener. The preferably provided flow screen should assist the uniform flow of the cooling air to the filaments. Within the scope of the invention, the flow screen arranged upstream or downstream of the flow straightener is not taken into account when determining the flow area of the flow straightener referred to above and claimed in claim 1.

Preferably, the flow screen has a mesh width or average mesh width of 0.1mm to 0.5mm, advantageously 0.1mm to 0.4mm and preferably 0.15mm to 0.34 mm. The mesh width is understood here to mean, in particular, the distance between two opposite lines of a flow screen or of a screen fabric of a flow screen. The mesh width here refers in particular to the minimum distance between two opposite lines of the mesh. When the flow screen has rectangular meshes with rectangular sides of different lengths, the mesh width refers to the distance between the two longer rectangular sides. Preferably, the flow sieve has a wire thickness or average wire thickness of 0.05mm to 0.35mm, preferably 0.05mm to 0.32mm, preferably 0.06mm to 0.30mm and very preferably 0.07mm to 0.28 mm. Within the scope of the invention, the flow screen has an identical or equally large mesh or substantially identical or equally large meshes on its screen surface. Advantageously, the openings of the same geometry or of substantially the same geometry are distributed uniformly over the screen surface.

According to a preferred embodiment of the invention, the flow area of the flow screen is 15% to 55%, advantageously 20% to 50% and preferably 25% to 45%. The flow area of the flow screen is understood here to mean, in particular, the flow area of the flow screen not occupied by the mesh wire and thus the area of the flow screen through which cooling air can freely flow.

A preferred embodiment of the invention is characterized in that the flow straightener and the flow screen arranged on its cooling air inflow side and/or on its cooling air outflow side are received by a common frame. As a result, a fixed or stable composite structure is produced between the flow straightener and the flow screen to the extent that it can be fixed in the air supply chamber as a whole. Preferably, at least one such frame with flow straightener and at least one flow screen is provided on two opposite sides of the cooling chamber or on both air supply chambers.

According to the invention, the flow channels of the flow straightener are arranged transversely to the flow direction of the filaments and advantageously transversely to the longitudinal center axis M of the device. According to a preferred embodiment of the invention, the flow channel is oriented perpendicular or substantially perpendicular to the flow direction of the thread or to the longitudinal center axis M of the device. Within the scope of the invention, the flow channels are oriented perpendicular or substantially perpendicular to a plane oriented orthogonal to the Machine Direction (MD) or perpendicular to a vertical plane extending through the longitudinal central axis M of the device. In principle, however, it is also possible that the flow channel can be arranged obliquely to the plane. The angle of inclination of the flow channels of the flow straightener can be uniform or different. When referring to the orientation and arrangement of the flow channels herein, this especially refers to the orientation or arrangement of the longitudinal axis of the flow channels. Within the scope of the invention, the flow channels of the flow straightener are configured to be linear or substantially linear.

A very preferred embodiment of the invention is characterized in that the flow channels of the flow straightener have a polygonal cross section, more particularly preferably a quadrangular to octagonal cross section. A very preferred embodiment of the invention is characterized in that the flow channels of the flow straightener have a hexagonal cross section. For this preferred case, the flow channels are therefore designed as if they were honeycomb-shaped.

According to a further preferred embodiment of the invention, the flow channel of the flow straightener has a round cross section, wherein the flow channel is preferably configured with a circular or elliptical cross section. Here, a circular cross section is preferred.

An additional embodiment of the invention is characterized in that the channel walls of the flow channel are configured in the shape of an airfoil or airfoil. In this case, the airfoil passage wall performs a directional function, in particular with regard to the cooling air flowing through. Advantageously, rectangular or substantially rectangular flow channels are constructed between wing-shaped or wing-shaped channel walls. Within the scope of the invention, the minimum distance between two adjacent airfoil-shaped or airfoil-shaped channel walls is 2mm to 15mm, preferably 3mm to 12mm and preferably 5mm to 10 mm.

A very preferred embodiment of the invention is characterized in that the inner area of the flow straightener through which the cooling air flows is 5m2 to 50m2, preferably 7.5m2 to 45m2 and preferably 10m2 to 40m2 per square meter of the flow cross section of the flow straightener. The inner area through which the cooling air flows is calculated from the sum of the flow-through or incident flow areas of the channel walls of the flow channel per square meter of the flow cross section of the flow rectifier. Within the scope of the invention, the flow screen of the flow straightener is not taken into account when calculating the internal area of the throughflow.

According to a very preferred embodiment of the invention, the length L of the flow channel of the flow straightener is 15mm to 65mm, preferably 20mm to 60mm, preferably 20mm to 55mm and very preferably 25mm to 50 mm. Preferably, the inner diameter or the smallest inner diameter Di of the flow channel is 2mm to 15mm, preferably 3mm to 12mm, preferably 4mm to 11mm and very preferably 5mm to 10 mm. Within the scope of the invention, the flow channels are arranged in the flow straightener in a compact and close contact with one another. Preferably, in the flow straightener the flow channels adjoin the flow channels and according to one embodiment only spacer elements may be present between the flow channels. Preferably, the mutual distance of the individual flow channels, or at least a large part of the flow channels, is smaller or significantly smaller than the smallest inner diameter Di of the flow channels. Advantageously, the flow channels are arranged in the flow straightener according to the principle of tight packing.

Within the scope of the invention, at least one supply line for supplying cooling air is connected to each air supply chamber, which supply line has a cross-sectional area QZ, wherein the cross-sectional area QZ of the supply line increases at the transition of the cooling air into the air supply chamber to a cross-sectional area QL of the air supply chamber, wherein the cross-sectional area QL 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. Advantageously, the cross-sectional area QZ of the supply duct is enlarged by a factor of 3 to 15 into the cross-sectional area QL of the air supply chamber. According to one embodiment of the invention, the cooling air volume flow supplied to the air supply chamber is divided into a plurality of partial volume flows which flow in via individual partial supply lines and/or via sections of a segmented supply line. In this case, the cooling air volume flow can be divided in particular into two to five, preferably two to three partial volume flows. When each partial volume flow flows in through a separate partial supply line, the cross-sectional area QZ of the partial supply line expands to the cross-sectional area QL of the relevant chamber section of the air supply chamber. The cross-sectional area QL is preferably at least twice as large, preferably at least three times as large, as the cross-sectional area QZ of the partial supply line. It is recommended that the cross-sectional area QZ of the supply line or of a part of the supply line widens stepwise, in particular in the form of a plurality of steps or continuously, to the cross-sectional area QL of the air supply chamber or to the cross-section of the chamber section of the air supply chamber.

According to a particularly preferred embodiment of the invention, at least one planar homogenization element for homogenizing the cooling air flow introduced into the air supply chamber is arranged in the air supply chamber upstream of the flow straightener in the flow direction of the cooling air and at a distance from the flow straightener. Within the scope of the invention, the planar homogenizing element has a plurality of openings and the free flow area (open area) of the planar homogenizing element is 1% to 20%, preferably 2% to 18%, and preferably 2% to 15%, of the total area of the planar homogenizing element. According to one embodiment variant, the at least one homogenizing element is configured as a perforated element, in particular as a perforated plate having a plurality of hole openings, and the hole openings preferably have an opening diameter of 1mm to 10mm, preferably 1.5mm to 9mm, and very preferably 1.5mm to 8 mm. According to a further preferred embodiment of the invention, the homogenization element is configured as a homogenization screen having a plurality or a multiplicity of mesh openings, wherein the homogenization screen preferably has a mesh opening width of 0.1mm to 0.5mm, preferably 0.12mm to 0.4mm and very preferably 0.15mm to 0.35 mm. It is recommended that the at least one planar homogenizing element is arranged upstream of the flow straightener of the respective air supply chamber or upstream of the flow screen of the flow straightener in the flow direction of the cooling air by a distance a1 of at least 50mm, preferably at least 80mm and preferably at least 100 mm. Advantageously, a plurality of homogenizing elements are arranged in the air supply chamber one after the other in the flow direction of the cooling air at a distance from the flow rectifier and at a distance from one another. The distance between two homogenizing elements arranged one after the other in the flow direction in the air supply chamber is at least 50mm, preferably at least 80mm and very preferably at least 100 mm.

In the device according to the invention, continuous filaments are spun by means of a spinning head and fed to a cooling chamber having an air feed chamber and a flow straightener. Within the scope of the invention, at least one spinning beam for spinning the thread 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 substantially perpendicular to the machine direction. It is also possible within the scope of the invention for the spinning beam to be arranged obliquely to the machine direction. According to a very preferred embodiment of the invention, at least one monomer suction device is arranged between the spinning head or spinning beam and the cooling chamber. Air is sucked out of the filament forming space below the spinning head by the monomer suction device. Gases which occur in addition to the filaments (such as monomers, oligomers, decomposition products, etc.) can thus be removed from the apparatus according to the invention. Advantageously, the monomer suction device has at least one suction chamber, to which preferably at least one suction fan is connected. It is recommended that a cooling chamber according to the invention with an air supply chamber and a flow straightener be connected to the individual suction devices in the flow direction of the thread.

Within the scope of the invention, the thread is guided from the cooling chamber into a drawing device for drawing the thread. Advantageously, an intermediate channel is connected to the cooling chamber, which intermediate channel connects the cooling chamber to the drawing shaft of the drawing device.

According to a particularly preferred embodiment of the invention, the combination of the cooling device and the drawing device or the combination of the cooling device, the intermediate channel and the drawing shaft is designed as a closed system. A closed system is understood here to mean, in particular, that no further air supply into the assembly takes place beyond the supply of cooling air into the cooling chamber. The flow straightener used according to the invention shows particular advantages in such a closed system. In this case, the air flow or the cooling air flow can be homogenized particularly simply and effectively.

Preferably, at least one diffuser is connected to the drawing device in the flow direction of the filaments, wherein the filaments are guided through the diffuser. Preferably, the diffuser comprises a diffuser cross section or a diverging diffuser section which diverges in the direction of the filament deposition. Within the scope of the invention, the threads are laid on a laying device for laying the threads or for laying the nonwoven fabric. The laying device is advantageously a laying screen belt or an air-permeable laying screen belt. The nonwoven web of filaments is transported away in the Machine Direction (MD) by the laying device or by the laying screen.

According to a preferred embodiment of the invention, the process air is sucked at least in the deposition area of the threads or from below through the deposition device or through the deposition screen belt. This results in a particularly stable filament or nonwoven layer. The suction is of particularly advantageous importance within the scope of the invention in combination with the flow straightener according to the invention. After laying on the laying device, the nonwoven web is advantageously supplied to further processing measures, in particular calendering.

Within the scope of the invention, the device according to the invention is designed or designed in such a way that it operates at a yarn or filament speed of more than 2000m/min, in particular at a yarn speed of more than 2200m/min or more than 2500m/min, for example at a yarn speed in the range of 3000 m/min. The filament speeds can be used insofar as filaments made of polyolefins, in particular polypropylene, or spunbonded nonwovens are produced. In the production of filaments or spunbonded non-woven fabrics made of polyester, in particular polyethylene terephthalate (PET), yarn or filament speeds of more than 4000m/min and even more than 5000m/min can also be achieved by the device according to the invention. For the high yarn speeds listed above (not only with respect to polyolefins but also with respect to polyesters), the configuration according to the invention of the air supply chamber with flow straightener has proved particularly advantageous.

The invention is based on the recognition that: by means of the device according to the invention, it is possible to achieve a spunbonded nonwoven with optimized quality and in particular with uniform properties over its surface extension. Defects or defects in the nonwoven fabric or in the surface of the nonwoven fabric can be completely prevented or at least largely minimized. These advantages can also be achieved, in particular, at plant capacities of greater than 150kg/h/m or greater than 200 kg/h/m. The configuration according to the invention of the air supply chamber or flow straightener ensures an optimized supply of cooling air into the cooling chamber, which ultimately achieves the advantageous properties of the spunbonded nonwoven. Within the scope of the invention, a very uniform and homogeneous cooling air supply can be achieved, and the filaments are positively influenced in this respect in accordance with the advantageous cooling air supply, so that undesirable defects in the nonwoven web can be prevented or largely minimized. The device according to the invention can nevertheless be realized with relatively simple and less expensive measures. Therefore, the apparatus is also characterized by low cost.

Drawings

The invention is explained in more detail below with the aid of the accompanying drawings, which illustrate only one exemplary embodiment. The figures show in schematic representation:

Figure 1 shows a longitudinal section of the device according to the invention,

Figure 2 shows an enlarged part of the cooling device of figure 1 comprising a cooling chamber and an air supply chamber,

Figure 3 shows a perspective view of an assembly with a flow straightener and flow screens connected upstream and downstream,

Fig. 4 shows a cross-section of a flow straightener section, with hexagonal or honeycomb shaped flow channels in cross-section,

FIG. 5 shows the contents according to FIG. 4, but with a flow channel which is circular in cross section, an

Fig. 6 shows the wing-shaped channel wall according to the description of fig. 4, but with the flow channels of the flow straightener.

Detailed Description

The drawing shows an apparatus according to the invention for producing a spunbonded nonwoven from continuous filaments 1, in particular from continuous filaments 1 made of thermoplastic. The apparatus comprises a spinning head 2 for spinning continuous filaments 1. The spun continuous filaments 1 are introduced into a cooling device 3 which has a cooling chamber 4 and air supply chambers 5, 6 arranged on two opposite sides of the cooling chamber 4. The cooling chamber 4 and the air supply chambers 5, 6 extend transversely to the machine direction MD and thus in the CD direction of the apparatus. The cooling air is introduced into the cooling chamber 4 from the opposed air supply chambers 5, 6. Preferably and in this embodiment, a monomer suction device 7 is provided between the spinning head 2 and the cooling device 3. The interfering gases occurring during the spinning process can be removed from the apparatus by means of the monomer suction device 7. The gas may be, for example, monomers, oligomers or decomposition products and the like.

Downstream of the cooling device 3 in the filament flow direction FS, a drawing device 8 is connected, in which the filaments 1 are drawn. Preferably and in this embodiment, the stretching device 8 has an intermediate channel 9 connecting the cooling device 3 with a stretching shaft 10 of the stretching device 8. According to a particularly preferred embodiment and in this exemplary embodiment, the combination of the cooling device 3 and the drawing device 8 or the combination of the cooling device 3, the intermediate channel 9 and the drawing shaft 10 is designed as a closed system. A closed system means here that, apart from the supply of cooling air in the cooling device 3, no further air supply into the assembly takes place.

Advantageously and in this exemplary embodiment, a diffuser 11 is connected to the drawing device 8 in the filament flow direction FS, through which the filaments 1 are guided. According to one embodiment and in this exemplary embodiment, a secondary air inlet gap 12 is provided between the drawing device 8 or the drawing shaft 10 and the diffuser 11, which serves to introduce secondary air into the diffuser 11. Preferably and in this embodiment, the filaments 1 are laid on a laying device configured to lay a sieve belt 13 after passing through the diffuser 11. Advantageously and in this embodiment, the laid filaments or nonwoven web 14 is then fed or carried away in the machine direction MD by said laid screen belt 13. Preferably and in this embodiment, a suction device for sucking air or process air through the laying device or through the laying screen belt 13 is provided below the laying device or below the laying screen belt 13. Here, preferably and in this embodiment, a suction area 15 is provided below the diffuser outlet and below the laying sieve belt 13. Advantageously and in this embodiment, said suction area 15 extends at least over the width B of the diffuser outlet. Preferably and in this embodiment, the width B of the suction zone 15 is greater than the width B of the diffuser outlet.

according to a preferred embodiment and in this embodiment, each air supply chamber 5, 6 is divided into two chamber sections 16, 17, from which cooling air of different temperatures can be supplied in each case. Thus, preferably and in this embodiment, cooling air having a temperature T1 may be supplied from the upper plenum section 16, respectively, while cooling air having a temperature T2 different from the temperature T1 may be supplied from the lower plenum section 17, respectively. According to one embodiment and in this exemplary embodiment, a flow straightener 18 is provided in each air supply chamber 5, 6 on the cooling chamber side, which flow straightener preferably and in this exemplary embodiment extends over the two chamber sections 16, 17 of each air supply chamber 5, 6.

The two flow straighteners 18 serve to straighten the flow of cooling air encountering the filament 1. Here, preferably and in this embodiment, each flow straightener 18 has a plurality of flow channels 19 oriented perpendicularly to the filament flow direction FS. These flow channels 19 are each delimited by channel walls 20 and are preferably constructed in a straight line.

according to a preferred embodiment and in this embodiment, the flow area of each flow straightener 18 is greater than 90% of the total area of the flow straighteners 18. Preferably and in this embodiment, the ratio of the length L of the flow channel 19 to the minimum internal diameter Di of the flow channel 19 is in the range between 1 and 10, advantageously in the range between 1 and 9.

according to a proven embodiment and in this exemplary 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 this embodiment, two flow screens 21 of each flow straightener 18 are arranged directly (i.e. abutting) upstream or downstream of the flow straighteners 18.

Preferably and in this embodiment, the two flow screens 21 of the flow straightener 18 or the surface of said flow screens 21 are oriented perpendicular to the longitudinal direction of the flow channel 19 of the flow straightener 18. It has proven advantageous for the flow screen 21 to have a mesh width w of 0.1mm to 0.5mm, advantageously 0.1mm to 0.4mm and preferably 0.15mm to 0.34 mm. It is furthermore advantageous if the flow screen has a wire thickness d of 0.05mm to 0.35mm, preferably 0.05mm to 0.32mm and very preferably 0.07mm to 0.28 mm. Within the scope of the invention, the mesh width w of the flow screen 21 is significantly smaller than the smallest inner diameter Di of the flow channels 19 of the flow straightener 18. The mesh width w of the flow screen 21 is preferably less than one sixth, very preferably less than one eighth and particularly preferably less than one tenth of the minimum internal diameter Di of the flow channel 19. Preferably, the area of the flow screen that is open and not occupied by wires is 21% to 50% and preferably 25% to 45% of the total area of the flow screen 21.

Fig. 4 to 6 show typical cross sections of the flow channels 19 of the flow straightener 18 used according to the invention. According to a preferred embodiment and in the exemplary embodiment according to fig. 4, the flow channels 19 of the flow straightener 18 have a hexagonal or honeycomb-shaped cross section. Here, the minimum inner diameter Di is measured between opposite sides of the regular hexagon (see fig. 4). In the embodiment according to fig. 5, the flow channels 19 of the flow straightener 18 have a circular cross section. Fig. 6 shows an embodiment of a flow straightener 18 according to the invention with airfoil-shaped passage walls 20. Advantageously and in this embodiment, the airfoil shaped passage walls 20 are separated from one another by spacers 22, which spacers 22 likewise constitute the passage walls of the flow passage. The airfoil passage wall 20 is configured in cross section to be arcuately curved (see right side of fig. 6). In principle, the airfoil passage wall 20 can also be constructed in a straight line and in this case the flow straightener 18 is constructed like a grid.