METHOD AND DEVICE FOR PRODUCING SPUNBONDED FABRIC

Abstract

A process for the production of spunbonded nonwoven (1) and a device for this purpose are shown, wherein a spinning mass (2) containing solvent is extruded through a plurality of nozzle holes of at least one spinneret (3) to form filaments (4) and the filaments (4) are drawn, in each case, in the extrusion direction, wherein the filaments (4) are deposited on a perforated conveying device (9) to form a spunbonded nonwoven (1) and, subsequently, are subjected to washing (10) for washing out the solvent from the filaments (4) and to hydroentanglement (11). So as to allow an inexpensive and efficient production of hydroentangled spunbonded nonwoven by means of the process, it is suggested that fresh water (12) is supplied to the hydroentanglement (11) and the waste water (13) from the hydroentanglement (11) is supplied to the washing (10) as wash water (14).

Claims

1. A process for producing a spunbonded nonwoven comprising: extruding a solvent comprising a spinning mass through a plurality of nozzle holes of at least one spinneret to form filaments, drawing the filaments, in each case, in an extrusion direction, wherein the filaments are deposited on a perforated conveying device to form the spunbonded nonwoven, washing the solvent from the filaments and subjecting the filaments to hydroentanglement wherein fresh water is supplied to the hydroentanglement and waste water from the hydroentanglement is supplied to the washing as wash water.

2. The process according to claim 1, wherein the fresh water is demineralized water.

3. The process according to claim 1, wherein the washing is a multi-stage countercurrent washing and the waste water from the hydroentanglement is passed in as countercurrent to the wash water through washing stages of the multi-stage countercurrent washing.

4. The process according to claim 3, wherein the hydroentanglement is designed as a final washing stage in the multi-stage countercurrent washing.

5. The process according to claim 1, further comprising degassing the waste water from the hydroentanglement and supplying the degassed waste water to the washing as the wash water.

6. The process according to claim 1, further comprising supplying the waste water from the washing to a water treatment system.

7. The process according to claim 6, comprising recovering the solvent from the waste water in the water treatment system.

8. The process according to claim 6, further comprising recovering purified water in the water treatment system from the waste water and supplying the purified water at least partially to the hydroentanglement as the fresh water.

9. The process according to claim 1, wherein the spunbonded nonwoven is subjected to the hydroentanglement on a second conveying device.

10. The process according to claim 9, wherein the second conveying device exhibits an embossing structure with an embossing pattern and the spunbonded nonwoven is provided with the embossing pattern by the hydroentanglement on the second conveying device.

11. The process according to claim 1, wherein the spinning mass is extruded into the filaments through the plurality of nozzle holes of more than one of the at least one spinneret arranged one behind another and the filaments are drawn, in each case, in the extrusion direction by a drawing air stream, wherein the respective filaments of the more than one spinneret are deposited on top of one another on the perforated conveying device to form a multi-layered spunbonded nonwoven.

12. The process according to claim 1, wherein the spunbonded nonwoven is a cellulosic spunbonded nonwoven, and the spinning mass is a solution of cellulose in a direct solvent, optionally a tertiary amine oxide.

13. A device for producing a spunbonded nonwoven, comprising: at least one spinneret for extruding a spinning mass into filaments; a drawing device for drawing the extruded filaments by means of a drawing air stream, the drawing device being allocated to the at least one spinneret; a perforated conveying device for depositing the filaments and forming the spunbonded nonwoven; a washing for washing the spunbonded nonwoven after formation; a hydroentanglement downstream of the washing the hydroentanglement and the washing each has an inlet for fresh water and an outlet for waste water, and wherein the outlet of the hydroentanglement is flow-connected to the inlet of the washing.

14. The device according to claim 13, wherein the outlet of the washing is flow-connected to a water treatment system for recovering solvent and the fresh water from the waste water of the washing.

15. The device according to claim 14, wherein the water treatment system is flow-connected to the inlet of the hydroentanglement for supplying the fresh water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Preferred embodiment variants of the invention are described in further detail below with reference to the drawings.

[0051] FIG. 1 shows a schematic illustration of the process according to the invention or, respectively, of the device according to the invention as per a first embodiment variant,

[0052] FIG. 2 shows a detailed schematic illustration of the washing and hydroentanglement according to a second embodiment variant of the invention,

[0053] FIG. 3 shows a schematic illustration of the process according to the invention or, respectively, of the device according to the invention as per a third embodiment variant,

[0054] FIG. 4 shows a schematic illustration of the process according to the invention or, respectively, of the device according to the invention as per a fourth embodiment variant, and

[0055] FIG. 5 shows a schematic illustration of the process according to the invention or, respectively, of the device according to the invention as per a fifth embodiment variant.

DETAILED DESCRIPTION OF THE INVENTION

[0056] FIG. 1 shows a schematic illustration of a process 100 for the production of a spunbonded nonwoven 1 according to a first embodiment variant of the invention and a device 200 for performing the process 100. 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. In this case, the cellulosic raw material for producing the spinning mass 2, which production is not shown in further detail in the figures, can be a conventional pulp made of wood or other plant-based starting materials, which is suitable for the production of lyocell fibres. However, it is also conceivable that the cellulosic raw material consists at least partly 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 ranging between 3% by weight and 17% by weight.

[0057] In a following step, the spinning mass 2 is then extruded through a plurality of nozzle holes in the spinneret 3 to form filaments 4. The extruded filaments 4 are then accelerated and drawn by a drawing air stream. For generating the drawing air stream, a drawing device 6 is provided in the spinneret 3, which device is supplied with drawing air 5 and ensures that the drawing air stream exits the spinneret 3 in order to accelerate the filaments 4 after their extrusion.

[0058] In one embodiment variant, the drawing air stream can emerge between the nozzle holes of the spinneret 3. In a further embodiment variant, the drawing air stream may alternatively emerge around the nozzle holes. However, this is not illustrated in further detail in the figures. Such spinnerets 3 comprising drawing devices 6 for generating a drawing air stream are known from the prior art (U.S. Pat. Nos. 3,825,380 A, 4,380,570 A, WO 2019/068764 A1).

[0059] Moreover, the extruded and drawn filaments 4 are additionally charged with a coagulation air stream 7, which is provided 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 4 with the coagulation air stream 7 and the coagulation liquid contained therein, the filaments 4 are coagulated at least partly, which, in particular, reduces adhesions between the individual extruded filaments 4.

[0060] The drawn and at least partially coagulated filaments 4 are then deposited in a random orientation on the conveying device 9, forming the spunbonded nonwoven 1 there. After its formation, the spunbonded nonwoven 1 is subjected to washing 10 and hydroentanglement 11.

[0061] In doing so, the hydroentanglement 11 is provided with demineralized fresh water 12, which is sprayed onto the spunbonded nonwoven 1 under high pressure, thereby solidifying it. The waste water 13 from the hydroentanglement 11 is supplied to the washing 10 as wash water 14. Since the washing 10 is located upstream of the hydroentanglement 11, the waste water 13 from the hydroentanglement 11 is contaminated with solvent only to a minor extent and can therefore be readily used as wash water 14 for the purposes of the washing 10.

[0062] Before the waste water 13 is supplied to the washing 10 as wash water 14, the waste water 13 is guided through a degassing device 15 especially in order to remove air that has been introduced into the waste water 13.

[0063] The waste water 16 of the washing 10 is finally discharged and can be supplied to a water treatment system 17 for the recovery of purified water and, respectively, solvent. The purified water can then be supplied back to the hydroentanglement 11 as fresh water 12, which, however, is not illustrated in further detail in the figures. Recovered solvent can be used in particular for the renewed production of spinning mass 2 from a cellulosic raw material, which, similarly, is not illustrated in further detail in the figures.

[0064] In a further embodiment variant, which is only indicated in the figures, the waste water 16 of the washing can be supplied to the coagulation device 8 at least partially also as a coagulation liquid.

[0065] In a following step, the washed and hydroentangled spunbonded nonwoven 1 is then subjected to drying in a dryer 18 in order to remove the remaining moisture and to obtain a finished spunbonded nonwoven 1. Finally, the process 200 is concluded by optionally winding 19 and/or packaging the finished spunbonded nonwoven 1.

[0066] FIG. 2 shows a detailed schematic illustration of the washing 10 and the hydroentanglement 11 in a process 101 or, respectively, a device 201 according to a second embodiment variant of the invention.

[0067] During the hydroentanglement 11, demineralized fresh water 12 is supplied to high-pressure pumps 20, which are connected to the hydroentanglement bars 21 and spray the fresh water 12 under high pressure onto the spunbonded nonwoven 1 on the conveyor belt 22 or, respectively, on the conveyor drum 23, whereby it is solidified.

[0068] In doing so, the waste water 13 is removed via suction pipes 24 as a suction device through the conveyor belt 22 and through the conveyor drum 23. In addition, the spunbonded nonwoven 1 is then dewatered again on the dewatering belt 25 before it is conveyed further to the dryer 18, which has not been illustrated in further detail.

[0069] The waste water 13 from the hydroentanglement 11, which is obtained from the suction pipes 24, contains a water/air mixture and is supplied to the degassing device 26 in order to remove the air. In doing so, the exhaust air 28 is removed from the waste water 13, for example, via a vacuum pump 27, while the gas-free waste water is collected in the storage container 29.

[0070] The waste water is then supplied from the storage container 29 to the washing 10 as wash water 14. As can be seen in FIG. 2, the washing 10 is, in this case, designed as a countercurrent washing 10 with two washing stages 30, 31, the wash water 14 being supplied to the second washing stage 31, which is downstream of the first washing stage 30. The waste water 32 of the second washing stage 31 is then supplied to the first washing stage 30 as wash water 33. The waste water 34 of the first washing stage, which is enriched with solvent from the spunbonded nonwoven 1, is then discharged from the washing 10 as waste water 16 or, as illustrated in FIG. 1, is supplied to a water treatment system 17.

[0071] The demineralized fresh water 12 thus gets enriched with solvent from the spunbonded nonwoven 1 on its way through the hydroentanglement 11 and through the washing 10 and is finally supplied to the water treatment system 17 in order to recover solvent and demineralized fresh water from the waste water 16.

[0072] FIG. 3 shows a detailed schematic illustration of the washing 10 and the hydroentanglement 11 in a process 102 or, respectively, a device 202 according to a third embodiment variant of the invention.

[0073] The embodiment variant in FIG. 3 differs from that in FIG. 2 merely in that the spunbonded nonwoven 1 is subjected to the washing 10 and the hydroentanglement 11, in each case, on a common second conveyor belt 35. As a result, the expenditure on mechanical engineering and on equipment for the device 202 can be reduced further.

[0074] With regard to all further features of the process 102 and the device 202, reference is made to the above description of the embodiment variant according to FIG. 2.

[0075] FIG. 4 shows a further detailed schematic illustration of the washing 10 and the hydroentanglement 11 in a process 103 and a device 203 according to a further embodiment variant of the invention.

[0076] As illustrated in FIG. 4, the conveyor drum 23 and the dewatering belt 25 have been omitted in the hydroentanglement 11, as compared to the variant depicted in FIG. 3. Therefore, the hydroentanglement 11 takes place exclusively on the conveyor belt 35 that is shared with the washing 10. In this case, the hydroentanglement 11 is preferably designed as the final stage of the multi-stage countercurrent washing 10, whereby the expenditure on mechanical engineering and on equipment can be reduced further. With regard to further features, reference is made to the descriptions of FIGS. 2 and 3.

[0077] In a further preferred embodiment, which is illustrated in FIG. 5, in the process 104 according to the invention and in the device 204 according to the invention, the conveyor belt 35 exhibits a three-dimensional embossing structure 36. During the hydroentanglement 11, the embossing pattern of the embossing structure 36 is then transferred to the spunbonded nonwoven 1, which displays the embossing pattern after the hydroentanglement 11. All other features remain as they have been described in accordance with FIGS. 2, 3 and 4.