METHOD FOR PRODUCING A SPUNBOND NONWOVEN

Abstract

The invention relates to a process (100) for the production of spunbonded nonwoven (1) wherein a spinning mass (2) is extruded through the nozzle holes (4) of at least one spinneret (3, 30) to form filaments (5, 50), the filaments (5, 50) are drawn in the extrusion direction and deposited on a first conveying device (9) to form the spunbonded nonwoven (1), and wherein the spunbonded nonwoven (1) is subjected to at least one washing (10). For increasing the throughput of the process without losses of quality, it is suggested that the spunbonded nonwoven (1) is subjected to the washing (10) at least partially on a perforated second conveying device (13) with a lower conveying speed with respect to that of the first conveying device (9), wherein the spunbonded nonwoven (1) is sprayed with washing liquid during the washing (10) and the washing liquid is discharged at least partially through the perforated second conveying device (13).

Claims

1. A process for the production of spunbonded nonwoven (1) wherein a spinning mass (2) is extruded through the nozzle holes (4) of at least one spinneret (3, 30) to form filaments (5, 50), the filaments (5, 50) are drawn in the extrusion direction and deposited on a first conveying device (9) to form the spunbonded nonwoven (1), and wherein the spunbonded nonwoven (1) is subjected to at least one washing (10), characterized in that the spunbonded nonwoven (1) is subjected to the washing (10) at least partially on a perforated second conveying device (13) with a lower conveying speed with respect to that of the first conveying device (9), wherein the spunbonded nonwoven (1) is sprayed with washing liquid during the washing (10) and the washing liquid is discharged at least partially through the perforated second conveying device (13).

2. A process according to claim 1, characterized in that the conveying speed of the second conveying device (13) is reduced by a factor of between 1 and 1000, in particular by a factor of between 1 and 100, particularly preferably by a factor of between 1 and 25, with respect to the first conveying device (9).

3. A process according to claim 1 or 2, characterized in that the spunbonded nonwoven (1) is deposited in loops (14) on the second conveying device (13).

4. A process according to any of claims 1 to 3, characterized in that, after washing (10), the spunbonded nonwoven (1) is subjected to further treatment steps (11, 12) on a third conveying device (15) at a conveying speed that is higher with respect to that of the second conveying device (13).

5. A process according to claim 4, characterized in that the conveying speed of the third conveying device (15) is increased by a factor of between 1 and 1000, in particular by a factor of between 1 and 100, particularly preferably by a factor of between 1 and 25, with respect to the second conveying device (13).

6. A process according to claim 4 or 5, characterized in that the third conveying device (15) has essentially the same conveying speed as the first conveying device (9).

7. A process according to any of claims 1 to 6, characterized in that the spunbonded nonwoven (1) is subjected to hydroentanglement (11) and/or drying (12) after the washing (10).

8. A process according to any of claims 1 to 7, characterized in that the washing (10) is a multi-stage countercurrent washing.

9. A process according to any of claims 1 to 8, characterized in that the spunbonded nonwoven (1) is deposited on the second conveying device (13) directly after it has been deposited and formed on the first conveying device (9).

10. A process according to any of claims 1 to 9, characterized in that the spunbonded nonwoven (1) is deposited on the second conveying device (13) directly before the washing (10).

11. A process according to any of claims 1 to 10, characterized in that the spinning mass (2) is extruded into filaments (5, 50) through at least a first spinneret (3) and a second spinneret (30), wherein the filaments (5) of the first spinneret (3) are deposited on the first conveying device (9) to form a first spunbonded nonwoven (1) and the filaments (50) of the second spinneret (30) are deposited on the first conveying device (9) to form a second spunbonded nonwoven, wherein the filaments (50) of the second spinneret (30) are deposited on the first conveying device (9) to form the second spunbonded nonwoven over the first spunbonded nonwoven (1) in order to obtain a multi-layered spunbonded nonwoven.

12. A process according to claim 11, characterized in that the multi-layered spunbonded nonwoven is unravelled into at least the first spunbonded nonwoven (1) and the second spunbonded nonwoven in a subsequent step, particularly after the washing (10).

13. A process according to any of claims 1 to 12, characterized in that the spunbonded nonwoven (1) is a cellulosic spunbonded nonwoven (1) and the spinning mass (2) is a solution of cellulose in a direct solvent, particularly a tertiary amine oxide.

14. A process according to any of claims 1 to 13, characterized in that the filaments (5, 50) are coagulated at least partly after the extrusion from the spinneret (3, 30), whereby in particular a coagulation air stream (7) comprising a coagulation liquid is assigned to the spinneret (3, 30) for the at least partial coagulation of the filaments (5, 50).

15. A process according to any of claims 1 to 14, characterized in that the coagulation liquid is a mixture of water and the direct solvent for cellulose, particularly a tertiary amine oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The embodiment variants of the invention are described in more detail below with reference to a drawing. FIG. 1 shows a schematic illustration of the process and a device according to a first embodiment variant.

WAYS OF IMPLEMENTING THE INVENTION

[0055] FIG. 1 shows a schematic illustration of the process 100 according to a first embodiment variant for the production of cellulosic spunbonded nonwoven 1 and a corresponding device 200 by means of which the process 100 is performed. In a first process step, a spinning mass 2 is produced from a cellulosic raw material and supplied to a spinneret 3 of the device 200. The cellulosic raw material for producing the spinning mass 2, which is not shown in further detail in the FIGURES, can be a conventional pulp made of wood or other plant-based starting materials. However, it is also conceivable that the cellulosic raw material consists of production waste from the production of spunbonded nonwoven or recycled textiles. In this case, the spinning mass 2 is a solution of cellulose in NMMO and water, with the cellulose content in the spinning mass 2 ranging between 3% by weight and 17% by weight.

[0056] The spinning mass 2 is then extruded in the spinneret 3 through a plurality of nozzle holes 4 to form the filaments 5. By supplying drawing air 6 to a drawing unit in the spinneret 3, the filaments 5 are drawn by means of a drawing air stream as they exit from the spinneret 3. In doing so, the drawing air 6 can emerge from openings in the spinneret 3 between the nozzle holes 4 and can be directed as a drawing air stream directly onto the extruded filaments 5, which is not shown in further detail in the FIGURES. After or already in the course of drawing, the extruded filaments 5 are charged with a coagulation air stream 7, which is generated by a coagulation device 8. The coagulation air stream 7 usually comprises a coagulation liquid, for example, in the form of vapour, mist, etc. Due to the contact of the filaments 5 with the coagulation air stream 7 and the coagulation liquid contained therein, the filaments 5 are coagulated at least partly, which, in particular, reduces adhesions between the individual extruded filaments 5. The filaments 5 that have been drawn and precipitated at least partly are then deposited in a random orientation on a first conveyor belt 9 as the first conveying device 9 to form the spunbonded nonwoven 1. By means of the conveyor belt 9, the spunbonded nonwoven 1 is then passed on to further treatment steps 10, 11, 12. In doing so, the spunbonded nonwoven 1 is subsequently subjected to at least one washing 10.

[0057] In order to increase the dwell time of the spunbonded nonwoven 1 in the washing 10, the spunbonded nonwoven 1 is deposited directly before the washing 10 on a second conveyor belt 13 as a second conveying device 13, which has a reduced conveying speed with respect to the first conveying device 9. The conveying speed of the spunbonded nonwoven 1 within the washing 10 is thus reduced in comparison to the conveying speed of the spunbonded nonwoven 1 before the washing 10, that is, while the filaments 5 are being deposited on the first conveyor belt 9. In doing so, the conveying speed is preferably reduced by a factor of between 1 and 1000. In another embodiment variant, the factor is between 1 and 100, and in yet another embodiment variant between 1 and 25. In order to accommodate the difference in the conveying speed between the first conveyor belt 9 and the second conveyor belt 13 in the spunbonded nonwoven 1, the spunbonded nonwoven 1 is deposited in loops 14 on the second conveyor belt 13. The spunbonded nonwoven 1 placed in loops 14 is then subjected to the washing 10, wherein it is essentially freed from solvent residues from the spinning mass 2.

[0058] After the washing 10, the spunbonded nonwoven 1 is deposited on a third conveyor belt 15, which has a higher conveying speed with respect to the second conveyor belt 13. In doing so, the third conveyor belt 15 preferably has the same conveying speed as the first conveyor belt 9, as a result of which the loops 14 are again pulled out completely. In a further embodiment variant, which is not shown in further detail, the third conveyor belt 15 can also have another conveying speed, which is different from the first conveyor belt 9 and which is increased by a factor of between 1 and 1000, preferably between 1 and 100, particularly preferably between 1 and 25, with respect to the second conveyor belt 13. On the third conveyor belt 15, the spunbonded nonwoven 1 is subjected to hydroentanglement 11, which is able to further adjust the internal structure of the spunbonded nonwoven 1. Besides, in the course of hydroentanglement 11, additional perforation patterns, embossing patterns or the like can be introduced into the spunbonded nonwoven 1, but this was not shown in further detail in the FIGURES.

[0059] Finally, the spunbonded nonwoven 1 is subjected to drying 12 in order to obtain a finished spunbonded nonwoven 1, wherein the process 100 is concluded by an optional winding 16 and/or packing process.

[0060] In a further embodiment variant, which is only indicated in the FIGURES, the device 100 or, respectively, the process 200 may have at least a first spinneret 3 and a second spinneret 30, with the spinning mass 2 being extruded simultaneously through the first spinneret 3 and the second spinneret 30 to form the filaments 5, 50. In doing so, the filaments 5, 50 are each drawn in the extrusion direction and coagulated at least partly, wherein the filaments 5 of the first spinneret 3 are deposited on the conveyor belt 9 to form a first spunbonded nonwoven 1 and the filaments 50 of the second spinneret 30 are deposited on the conveyor belt 9 to form a second spunbonded nonwoven. The filaments 50 of the second spinneret 30 are deposited on the conveyor belt 9 to form the second spunbonded nonwoven over the first spunbonded nonwoven 1 in order to obtain a multi-layered spunbonded nonwoven, which is not shown in further detail in the FIGURES.

[0061] Preferably, the first spunbonded nonwoven 1 and the second spunbonded nonwoven undergo the washing 10 jointly in the form of the multi-layered spunbonded nonwoven, wherein the multi-layered spunbonded nonwoven is deposited in loops 14 on the second conveyor belt 13 at a conveying speed that is lower with respect to that of the first conveyor belt 9. Preferably, the multi-layered spunbonded nonwoven can then be unravelled into at least the first spunbonded nonwoven 1 and the second spunbonded nonwoven in a step following the washing 10, with the first spunbonded nonwoven 1 and the second spunbonded nonwoven separately undergoing further steps, such as hydroentanglement 11 and/or drying 12, after unravelling.

[0062] Alternatively, the first spunbonded nonwoven 1 and the second spunbonded nonwoven may undergo the hydroentanglement 11 also jointly, whereby they are interconnected permanently to form the multi-layered spunbonded nonwoven.

[0063] Likewise, the first spunbonded nonwoven 1 and the second spunbonded nonwoven may each have different internal properties, for example, a different weight per unit area, and thus form a multi-layered spunbonded nonwoven with properties variable in cross-section.

[0064] In a further embodiment variant, which is not illustrated in the FIGURES, the first conveying device 9 is a conveyor drum and the second conveying device 13 is a conveyor belt.

[0065] In yet another embodiment, both the first conveying device 9 and the second conveying device 13 are a conveyor drum.