METHOD FOR PRODUCING SPUNBONDED FABRIC

Abstract

A process (100, 101) for the production of spunbonded nonwoven (1) and a device (200, 201) are shown, comprising an embossing pattern (10), wherein a spinning mass (2) is extruded through a plurality of nozzle holes of at least one spinneret (3, 30) to form filaments (4, 40) and the filaments (4, 40) are drawn by a drawing air stream (5, 50), in each case, in the extrusion direction, with the filaments (4, 40) being deposited on a perforated tray (7) of a conveying device (8) to form a spunbonded nonwoven (1). So as to allow an efficient, technically simple and inexpensive introduction of the embossing pattern into the spunbonded nonwoven, it is suggested that the perforated tray (7) has an embossing structure (9) with an embossing pattern (10), the filaments (4, 40) are pressed into the embossing structure (9) by the drawing air stream (5, 50) and the spunbonded nonwoven (1) thus formed is provided with the embossing pattern (10).

Claims

1. A process for producing a spunbonded non woven with an embossing pattern comprising, extruding a spinning mass through a plurality of nozzle holes of at least one spinneret form filaments; and drawing the filaments by a drawing air stream, wherein in each case, in an extrusion direction, with the filaments being deposited on a perforated tray of a conveying device to form the spunbonded non woven, the perforated tray has an embossing structure with the embossing pattern, the filaments are pressed into the embossing structure by the drawing air stream, and the spunbonded nonwoven thus formed is provided with the embossing pattern.

2. The process according to claim 1, further comprising subjecting the spunbonded nonwoven to at least one treatment step after formation, wherein the embossing pattern is substantially preserved in the spunbonded nonwoven after the at least one treatment step.

3. The process according to claim 2, wherein the at least one treatment step comprises washing and/or drying.

4. The process according to claim 1, wherein the spunbonded non woven provided with the embossing pattern undergoes hydroentanglement after formation, with the spunbonded nonwoven being provided with a second embossing pattern during the hydroentanglement.

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

6. The A process according to claim 1, wherein the spunbonded nonwoven is a cellulosic spunbonded nonwoven hand the spinning mass is a solution of cellulose in a direct solvent, optionally a tertiary amine oxide in an aqueous solution.

7. The process according to claim 6, further comprising, after extrusion from the plurality of the at least one spinneret, coagulating the filaments least partly, optionally by a coagulation air stream, which optionally comprises a coagulation liquid.

8. A device for producing a spunbonded nonwoven with an embossing pattern, 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; and a conveying device having a perforated tray for depositing the filaments and forming the spunbonded nonwoven, wherein the perforated tray has an embossing structure with the embossing pattern for pressing the filaments into the embossing structure by means of the drawing air stream and providing the embossing pattern in the spunbonded nonwoven that has been formed.

9. The device according to claim 8, further comprising a washing for washing the spunbonded nonwoven after formation and a dryer for drying the spunbonded nonwoven after the washing.

10. The device according to claim 8, wherein the device exhibits a suction underneath the perforated tray for discharging the drawing air stream.

11. The device according to claim 9, further comprising a hydroentanglement on a conveyor belt (18) between the washing and the dryer, the conveyor belt having a second embossing structure with a second embossing pattern.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Preferred embodiment variants of the invention are described in further detail below with reference to the drawings.

[0041] FIG. 1 shows a schematic illustration of the process according to the invention as per a first embodiment variant,

[0042] FIG. 2 shows a schematic illustration of the process according to the invention as per a second embodiment variant, and

[0043] FIG. 3 shows a schematic detailed view of the extrusion, drawing and deposition of the filaments according to the process illustrated in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0044] FIG. 1 shows a process 100 according to the invention for the production of a spunbonded nonwoven 1 with an embossing pattern 10 and a device 200 for performing the process 100 according to a first embodiment variant of the invention. 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 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 of or contains 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.

[0045] 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. In this connection, FIG. 3 shows a detailed schematic illustration of the process sequence. The extruded filaments 4 are then accelerated and drawn in a drawing air stream 5. For generating the drawing air stream 5, a drawing device 6 is provided in the spinneret 3, which ensures that the drawing air stream 5 exits the spinneret 3 in order to accelerate the filaments 4 after their extrusion.

[0046] 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 can alternatively emerge around the nozzle holes. However, this is not shown in further detail in the figures. Such spinnerets 3 comprising drawing devices 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).

[0047] In the illustrated preferred embodiment, the extruded and drawn filaments 4 are additionally charged with a coagulation air stream 11, which is provided by a coagulation device 12. The coagulation air stream 11 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 11 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.

[0048] As can be seen furthermore from FIG. 3, the drawn and at least partially coagulated filaments 4 are then deposited in a random orientation on the tray 7 of a conveying device 8. In this case, the tray 7 of the conveying device 8 has an embossing structure 9 with an embossing pattern 10. The extruded and drawn filaments 4 are then pressed into the tray 7 by means of the drawing air stream 5, forming the spunbonded nonwoven 1 there. After the spunbonded nonwoven 1 has been formed, it exhibits the embossing pattern 10 from the embossing structure 9. The embossing pattern 10 or, respectively, the three-dimensional structure of the spunbonded nonwoven 1 can thus be embossing according to the invention by the embossing structure 9 in the tray 7, and the directly structured cellulosic spunbonded nonwoven 1 according to the invention can be produced without any additional downstream process steps.

[0049] As illustrated in FIG. 1, in the device 200 according to the invention and, respectively, in the process 100, in particular hydroentanglement may be omitted, as a result of which the length, the investment costs and the operating costs of the device 200 can advantageously be reduced.

[0050] Following the formation, the spunbonded nonwoven 1 is guided across the conveyor belt 13 through a washing 14 in which the spunbonded nonwoven 1 is washed in order to free it from residues of the solvent, namely the NMMO contained in the spinning mass 2. In a preferred embodiment variant, the washing 14 is, in this case, a multi-stage countercurrent washing, which, however, has not been illustrated in the figures. In a next step, the washed spunbonded nonwoven 1 is then supplied to a drying in a dryer 15 in order to remove the remaining moisture and to obtain a finished spunbonded nonwoven 1.

[0051] Finally, the process 200 is completed by optionally winding 16 and/or packaging the finished spunbonded nonwoven 1.

[0052] In FIG. 2, a process 101 according to the invention and a device 201 according to a second embodiment variant of the invention are illustrated. The formation of the spunbonded nonwoven 1 including extrusion, drawing, coagulation and deposition on the tray 7 exhibiting the embossing structure 9 takes place identically as described above for the first embodiment variant with reference to FIGS. 1 and 3.

[0053] In addition, in the process 201 according to the second embodiment variant, in addition to the direct structuring according to the invention on the tray 7, a hydroentanglement 17 is provided. In this case, the spunbonded nonwoven 1 is deposited on a further conveyor belt 18 after washing 14, the conveyor belt 18 having a second embossing structure 19 with a second embossing pattern 20. The spunbonded nonwoven 1, which already exhibits the embossing pattern 10, is then hydroentangled over the conveyor belt 18, i.e., sprayed with water at a high pressure, whereby the spunbonded nonwoven 1 is pressed into the second embossing structure 19 of the conveyor belt 18 and the second embossing pattern 20 is transferred to the spunbonded nonwoven 1.

[0054] By combining the direct structuring on the tray 7 with the embossing structure 9 and the hydroentanglement with the second embossing structure 19, it becomes possible to manufacture even more product variations of the spunbonded nonwoven 1 with embossing patterns 10, 20. Despite the fact that hydroentanglement 17 is provided, both the investment costs of the device 201 and the operating costs of the hydroentanglement 17 can be reduced substantially in comparison to systems from the prior art, since a large part of the three-dimensional structuring of the spunbonded nonwoven 1 takes place already on the tray 7.

[0055] In a further embodiment variant, which is only indicated in the figures, the device 100 and, respectively, the process 200 can have at least a first spinneret 3 and a second spinneret 30, the spinning mass 2 being extruded simultaneously through the first spinneret 3 and the second spinneret 30 to form the filaments 4, 40. In doing so, the filaments 4, 40 are each drawn in the extrusion direction by means of a drawing air stream 5, 50 and coagulated at least partly, wherein the filaments 4 of the first spinneret 3 are deposited on the conveying device 8 to form a first spunbonded nonwoven 1 and the filaments 40 of the second spinneret 30 are deposited on the conveying device 8 to form a second spunbonded nonwoven.

[0056] The filaments 40 of the second spinneret 30 are deposited on the conveying device 8 to form the second spunbonded nonwoven on the first spunbonded nonwoven 1 in order to obtain a multi-layered spunbonded nonwoven, which is not shown in further detail in the figures. In the multi-layered spunbonded nonwoven according to the invention, the embossing pattern 10, which has been introduced into the first spunbonded nonwoven 1 through the tray 7, can surprisingly be reproduced also through the entire multi-layered spunbonded nonwoven.

[0057] The first spunbonded nonwoven 1 and the second spunbonded nonwoven preferably undergo the washing 14 and the dryer 15 jointly in the form of the multi-layered spunbonded nonwoven.

[0058] In a further embodiment variant, which is not shown in further detail in the figures, the multi-layered spunbonded nonwoven can be unravelled into at least the first spunbonded nonwoven 1 and the second spunbonded nonwoven in a further step, in particular following the washing 14, wherein the first spunbonded nonwoven 1 and the second spunbonded nonwoven may undergo further steps, such as hydroentanglement 17 and/or drying 15, separately after unravelling.

[0059] Alternatively, in a further embodiment variant, the first spunbonded nonwoven 1 and the second spunbonded nonwoven may undergo the hydroentanglement 17 also jointly, whereby they are interconnected permanently to form the multi-layered spunbonded nonwoven.

[0060] Finally, the multi-layered spunbonded nonwoven can be supplied to an optional winding 16.

[0061] Likewise, the first spunbonded nonwoven 1 and the second spunbonded nonwoven may each have different internal properties, for example, a different basis weight or different air permeabilities, and may thus form a multi-layered spunbonded nonwoven with properties variable in cross-section.

Examples

[0062] The process according to the invention is illustrated below using an example. In each case, spunbonded nonwovens were produced in accordance with the process forming the subject manner, and the thickness of the spunbonded nonwoven was determined in accordance with DIN EN ISO 9073-2: 1997-02 (test method for nonwoven fabrics, part 2: determination of thickness).

[0063] In the examples, cellulosic spunbonded nonwovens were, in each case, produced from a lyocell spinning mass, with a solution of cellulose in a mixture of water and NMMO being used as the spinning mass.

[0064] The cellulose throughput per spinneret was 300 kg/b/m in all examples. The drawing air pressure of the drawing air stream was 0.5 bar in each of the examples.

[0065] In the example, the spunbonded nonwovens were produced as described above using the process according to the invention. In doing so, the spunbonded nonwovens that were produced had basis weights ranging between 10 and 40 g/m2. As per the information given in Table 1, the spunbonded nonwovens were thereby formed on a tray according to the invention provided with an embossing structure or on a conventional (unstructured) tray.

[0066] Table 1 shows the measured thicknesses of the spunbonded nonwovens that were produced. It thereby becomes evident that, by the direct structuring of the spunbonded nonwoven during the deposition with an embossing structure, a significant change in the thickness of the spunbonded nonwoven can be achieved despite otherwise identical process parameters.

TABLE-US-00001 TABLE 1 Thicknesses of the spunbonded nonwovens measured according to the example Basis weight tray with embossing thickness according to (g/m.sup.2) structure DIN 29073 (mm) 10 no 0.09-0.14 10 yes 0.21-0.25 40 no 0.25-0.28 40 yes 0.37-0.44