Title:
METHOD AND APPARATUS FOR STRENGTHENING A RUNNING NON-WOVEN WEB, AND A NON-WOVEN WEB
Kind Code:
A1


Abstract:
The invention relates to a method and an apparatus for strengthening a running non-woven web. For this purpose, the non-woven web is penetrated by a plurality of fluid streams. In order to create a surface structure, the fluid streams are generated by a movable nozzle beam, which is guided back and forth at a defined amplitude substantially transversely to the running direction of the non-woven web. In order to obtain enough flexibility and a sufficient volume in the non-woven web in spite of the strengthening effect, the amplitude for moving the fluid streams back and forth is selected in such a way according to the invention that the points of impact created in the non-woven web by adjacent fluid streams do not intersect an imaginary separating line in the running direction. To this avail, the amplitude of the back and forth movement of the nozzle beam is adjusted so as to be smaller than half the distance between two nozzle outlets disposed next to each other in the row.



Inventors:
Mooshammer, Anton (Aschersleben, DE)
Application Number:
12/141186
Publication Date:
12/18/2008
Filing Date:
06/18/2008
Assignee:
Oerlikon Textile GmbH & Co. KG
Primary Class:
Other Classes:
28/257, 28/271, 28/104
International Classes:
D04H13/00; D02G1/16; D04H18/04
View Patent Images:



Primary Examiner:
BOYD, JENNIFER A
Attorney, Agent or Firm:
ALSTON & BIRD LLP (CHARLOTTE, NC, US)
Claims:
That which is claimed:

1. A method for strengthening a running non-woven web, said method comprising: generating a plurality of fluid streams, which are guided in a row arrangement transversely to the running direction of the non-woven web at a certain spacing, and which impact the non-woven web substantially perpendicularly and penetrate the fiber material of the non-woven web; and moving the fluid streams back and forth at an amplitude which is selected in such a way that points of impact created in the non-woven web by adjacent fluid streams do not intersect an imaginary separating line in the running direction.

2. The method according to claim 1, wherein the fluid streams are moved back and forth at a guiding speed, which is lower than a running speed of the non-woven web.

3. The method according to claim 1, wherein the fluid streams are moved back and forth at a guiding speed, which is greater than a running speed of the non-woven web.

4. The method according to claim 1, wherein the fluid streams are formed by water jets, which are produced with a pressure gradient ranging from 30 bar to 600 bar by a plurality of nozzle openings having a hole diameter ranging from 0.05 mm to 0.5 mm.

5. The Method according to claim 4, wherein the water jets are produced by several rows of nozzle openings disposed in a staggered manner relative to each other.

6. The method according to claim 5, wherein the rows of nozzle openings are moved back and forth independently of each other, the amplitudes being selected in such a manner that points of impact in the non-woven web do not intersect each other.

7. An apparatus for strengthening a running non-woven web, said apparatus comprising: a guiding means for guiding a non-woven web; and a movable nozzle beam above the guiding means, the nozzle beam comprising a plurality of nozzle openings which are disposed in a row next to each other and extend substantially transversely to the guided non-woven web and are connected to a fluid source, the nozzle beam being configured to be guided back and forth by a drive transversely to the non-woven web, wherein the amplitude of the back and forth movement of the nozzle beam is smaller than half the distance between two adjacent nozzle openings in the row.

8. An apparatus according to claim 7, wherein the guiding means is formed by a driven screen belt or a driven screen roller, and wherein a controllable drive is assigned to the guiding means for adjusting a speed of the non-woven web.

9. An apparatus according to claim 8, wherein a speed of the screen belt or a circumferential speed of the screen roller is greater than a guiding speed of the nozzle beam.

10. An apparatus according to claim 8, wherein a speed of the screen belt or a circumferential speed of the screen roller is lower than a guiding speed of the nozzle beam.

11. An apparatus according claim 7, wherein the nozzle openings, which are disposed next to each other in a row, are each spaced apart by a distance ranging from 1 mm to 10 mm.

12. An apparatus according to claim 7, wherein the nozzle openings have a hole diameter ranging from 0.05 mm to 0.5 mm.

13. An apparatus according to claim 7, wherein the fluid source provides water, which is maintained at an operating pressure ranging from 30 bar to 600 bar in a pressure chamber of the nozzle beam, which pressure chamber is configured to be connected to the nozzle openings.

14. An apparatus according to claim 7, wherein the plurality of nozzle openings is distributed in several rows on one or more nozzle beams and wherein the nozzle openings of adjacent rows are staggered in relation to each other.

15. A non-woven web having a plurality of melt-spun fibers, said non-woven web comprising: a surface structure produced by fluid consolidation, wherein the surface structure is formed by a line pattern comprising zigzagged structure lines, which do not have any points of intersection.

16. The non-woven web according to claim 15, wherein the surface structure forms a consolidated surface portion, which ranges from 5% to 50% of the total surface.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of International Application No. PCT/EP2006/012115, filed Dec. 15, 2006, and which designates the U.S. The disclosure of the referenced application is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a method for strengthening a running non-woven web, an apparatus for strengthening a running non-woven web, and a non-woven web having a plurality of melt-spun fibers.

BACKGROUND OF THE INVENTION

When producing non-woven webs formed by depositing of a plurality of fibers, it is known to consolidate the non-woven web in a process of subsequent treatment, in order to increase the cohesion of the fibers within the non-woven web. Apart from chemical and thermal consolidation methods, mechanical consolidation methods are used in particular, in which the non-woven web is penetrated by additional means, in order to interlace the fibers with one another. In recent times, the water-jet needling technique, in particular, has gained in significance as a consolidation method. Here, columnar water jets are produced under a high pressure. These water jets impact the non-woven web substantially perpendicularly and penetrate the latter. The water jets result in compaction and swirling of the fibers at the point of impact so that surface structures are formed on the non-woven web. Two versions of the method are known from the prior art for producing such surface-structured and consolidated non-woven webs.

DE 198 28 118 (related to U.S. Pat. No. 6,105,522) discloses a method and an apparatus for strengthening a non-woven web by means of a water jet, in which method a nozzle beam comprising a plurality of nozzle openings is disposed above a guiding means for guiding a non-woven web. The nozzle beam is held movably above the non-woven web in such a way that the nozzle beam can, by means of a drive, perform a back and forth movement substantially transversely to the running direction of the non-woven web. Water jets are produced by means of high pressure by each of the nozzle openings disposed on the lower side of the nozzle beam. The number of nozzle openings, the arrangement of the nozzle openings as well as the reciprocating movement of the nozzle beam are laid out so as to achieve the most uniformly possible closed surface structure in the form of a smooth non-woven web. However, such non-woven webs comprising two-dimensional surface structures are completely unsuitable for absorbing additives such as impregnating agents due to the lack of voluminous regions.

U.S. Pat. No. 4,069,563 discloses another method and apparatus for strengthening a non-woven web. Here, the nozzle openings formed on a nozzle beam are held stationarily in relation to the non-woven web. The nozzle beam is mounted above the guiding means at a distance therefrom. The water jets produced by the nozzle beam and the nozzle openings impact the running non-woven web substantially perpendicularly so that a linear surface structure is formed on the non-woven web. Depending on the number and arrangement of the nozzle openings, it is possible to consolidate smaller or larger surface portions in the non-woven web to suit requirements. However, the disadvantage of such non-woven webs is that the linear surface structure brings about a non-uniform strength of the non-woven web. It was thus established that the non-woven web had substantially higher strength in the running direction, which is also referred to among experts as machine direction (MD) in relation to the cross direction (CD). Such differences in strength are considerably greater especially in the production of voluminous non-woven webs comprising few consolidated surface portions.

It is an object of the invention to provide a method for strengthening a running non-woven web of the generic kind and an apparatus for implementing said method, which method and apparatus enable the production of surface-structured non-woven webs having the most uniform possible surface properties and large, voluminous surface regions.

Another object of the present invention is to provide a non-woven web having a linear surface structure and the maximum possible strength.

SUMMARY OF THE INVENTION

These objects and others are achieved by means of a method, apparatus, and non-woven web having the features defined and claimed herein.

Preferred refinements of the invention are also defined by the features and combinations of features defined and claimed herein.

The invention is characterized by the fact that a linear surface structure produced for strengthening the non-woven web is based on a plurality of diagonally running structure lines disposed next to each other. In the production of non-woven fibrous webs, the fibers are usually oriented in the running direction of the non-woven web. Therefore, the obliquely running structure lines help create consolidated surface regions, which result in a longitudinally and transversely oriented swirling effect of the fibers. In this respect, a uniform strength is produced, which is substantially independent of the tensile direction on the non-woven web. Another advantage of the invention is that the fibers within the non-woven web have increased freedom of movement despite a consolidated surface structure. In the method of the invention, the amplitude for the back and forth movement of the fluid streams is selected in such a way for this purpose that the points of impact produced in the non-woven web by adjacent fluid streams do not intersect an imaginary separating line. The consolidated surface regions produced within the non-woven web thus substantially represent a uniform swirling effect and interlacing of the fibers. The invention thus advantageously prevents the overlapping and intersection of the linear surface jets and double swirling of the fibers within the non-woven web.

Depending on the number and the arrangement of nozzle openings, the structure lines in the non-woven web can be formed at different angles of inclination relative to the running direction of the non-woven web. In order to achieve the most acute-angled curve of inclination of the structure lines, that version of the method of the invention is particularly advantageous in which the fluid streams are moved back and forth at a guiding speed, which is lower than a running speed of the non-woven web. The non-woven web thus moves faster per time unit than the transversely moved fluid streams.

If a larger inclination of the structure lines is to be produced, then that version of the method of the invention is preferably used in which the fluid streams are moved back and forth at a guiding speed, which is greater than a running speed of the non-woven web. The selection of the inclination of the structure lines advantageously influences the ratio of the strength in the running direction (MD) to the strength in the cross direction (CD). It is thus possible to produce special effects on the non-woven web by changing the inclination of the structure lines.

The method of the invention is preferably implemented using water jets as fluid streams, which are produced with a pressure gradient ranging from 30 bar to 600 bar by means of a plurality of nozzle openings having a diameter ranging from 0.05 mm to 0.5 mm.

The water jets can be produced by one or more rows of nozzle openings, which are staggered in relation to each other, so that both the width and the number of structure lines are selectable.

If several nozzle rows, which are moved independently of each other, are used for strengthening a non-woven web, the amplitudes for moving the nozzle rows are selected in such a way that the structure lines do not produce any points of intersection on the surface of the non-woven web.

The apparatus of the invention is characterized by the fact that relatively large distances can be formed between the nozzle openings for strengthening a non-woven web so that the number of nozzle openings can be kept appropriately low in order to produce conventional surface-structured non-woven webs having equal strength. This helps economize on energy and water by up to 30%.

The apparatus of the invention is also suitable to produce higher-strength non-woven webs, which are formed with uniform strength. The apparatus of the invention solves the problem underlying the invention by adjusting the amplitude of the back and forth movement of the nozzle beam to be smaller than half the distance between two nozzle openings disposed next to each other in a row. It is thus possible to firstly prevent unwanted overlaps of structure lines and secondly ensure sufficient zones of non-consolidated surface regions between the structure lines, which non-consolidated surface regions enable sufficient mobility of the fibers within the non-woven web.

In order to produce random line patterns having zigzagged structure lines when producing the surface structure on the non-woven web, that refinement of the apparatus of the invention is preferably used in which the guiding means and the nozzle beam are driven by separate controllable drives. The guiding means is formed by a driven screen belt or a driven screen roller. It is thus possible to use alternative versions of the apparatus for producing the consolidated non-woven web.

In a first version of the apparatus of the invention, the speed of the belt or the circumferential speed of the roller is greater than a guiding speed of the nozzle beam.

In order to achieve the flattest possible structure lines in the non-woven web, that version of the refinement of the invention is used, in which the speed of the belt or the circumferential speed of the roller is lower than a guiding speed of the nozzle beam.

It has been seen that those arrangements of nozzle openings, in which the nozzle openings disposed next to each other in a row at a distance of 10 mm from each other, yielded satisfactory results for strengthening conventional non-woven webs. Depending on requirements made of the non-woven web, it is possible to reduce the distance between the nozzle openings to up to 1 mm.

The fluid streams could be produced by nozzle openings having a diameter ranging from 0.05 mm to 0.5 mm.

In principle, water or air jets can be used as fluid streams. But the fluid source preferably provides water, which is held in a pressure chamber of the nozzle beam at an operating pressure ranging from 30 bar to 600 bar, which pressure chamber can be connected to the nozzle openings. It is thus possible to advantageously consolidate even thicker non-woven webs or multi-layer non-woven webs.

In order to produce the broadest possible structure lines or a dense arrangement of structure lines in the non-woven web, the plurality of nozzle openings can be distributed in accordance with an advantageous refinement of the invention in several rows on one or more nozzle beams. The nozzle openings of adjacent rows are preferably staggered in relation to each other.

The non-woven web of the invention is characterized, in particular, by uniform strength in all directions, and especially an increased strength in the cross direction (CD). Thus, larger non-consolidated surface regions can be implemented in the non-woven web, which enable the non-woven web to be used as carrier material for bitumen or in cleaning tissues, filters or clothing. The voluminous, non-consolidated regions within the non-woven web thus permit the absorption of bonding agents, impregnating agents or other additives.

However, simple air cushions can also be incorporated into the non-consolidated regions for the purpose of increasing the non-woven web volume. The non-woven web of the invention thus advantageously combines the characteristics of high volume with high strength.

For this purpose, in accordance with a preferred refinement of the non-woven web of the invention, the surface portion that is consolidated by the surface structure is limited to 5% to max. 50% in relation to the total area of the non-woven web.

BRIEF DESCRIPTION OF THE DRAWINGS

The method of the invention is described in more detail below on the basis of some exemplary embodiments of the apparatus of the invention with reference to the attached figures, in which:

FIG. 1 schematically shows a view of a first exemplary embodiment of the apparatus of the invention;

FIG. 2 schematically shows a plan view of an exemplary embodiment of the non-woven web of the invention;

FIG. 3 schematically shows a plan view of an exemplary embodiment of a nozzle beam;

FIG. 4 schematically shows several adjacent nozzle openings of a row arrangement in accordance with an exemplary embodiment of the invention;

FIG. 5 schematically shows several nozzle openings in a double row in accordance with an exemplary embodiment of the invention;

FIG. 6 schematically shows the speed distribution when producing a structure line in accordance with an exemplary embodiment of the invention;

FIG. 7 schematically shows a plan view of another exemplary embodiment of a nozzle beam; and

FIG. 8 schematically shows a cross-sectional view of another exemplary embodiment of the apparatus of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 schematically shows a view of a first exemplary embodiment of the apparatus of the invention for implementing the method of the invention for strengthening a running non-woven web. The exemplary embodiment comprises a guiding means 1 for guiding a non-woven web 3. For this purpose, the guiding means 1 consists of a screen belt 4, which is preferably designed as an endless belt and is driven by means of a belt drive 5 at a pre-determined belt speed. The screen belt 4 is designed to be permeable to air and water. A non-woven web 3 formed of a plurality of deposited fibers rests on the surface of the screen belt 4.

A nozzle beam 2 is disposed above the guiding means 1 at a small distance from the non-woven web 3. The nozzle beam 2 extends substantially transversely over the width of the non-woven web 3. The nozzle beam 2 is held such that it can move and it is guided back and forth by means of a drive 9 at a predefined amplitude. The nozzle beam 2 moves substantially transversely to the running direction of the non-woven web 3.

A plurality of nozzle openings (not shown here) is disposed in a row and spaced apart on the lower side of the nozzle beam. Each of the nozzle openings is connected by means of a pressure chamber to a fluid inlet 7. Fluid, preferably water, is supplied to the nozzle beams 2 by way of the fluid inlet 7, which fluid is maintained at a high pressure in a pressure chamber inside the nozzle beam and is dispensed by means of the nozzle openings on the lower side of the nozzle beam in the form of a plurality of fluid streams. In FIG. 1, reference numeral 6 indicates the fluid streams being discharged from the nozzle openings on the lower side of the nozzle beam 2.

During operation, the apparatus shown in FIG. 1 continuously consolidates a running non-woven web by means of a plurality of fluid streams, which penetrate the non-woven web. For this purpose, the screen belt 4 transports the non-woven web 3 at a defined running speed. The non-woven web consists of a plurality of fine fibers or pieces of fiber, which were produced, for example, in a melt spinning process and which form the non-woven web. For the purpose of strengthening the non-woven web, the nozzle beam 2 produces a plurality of fluid streams 6, which impact the non-woven web 3 substantially vertically and which penetrate the fiber material of the non-woven web 3. This causes the individual fiber strands to swirl and interlace. This swirling and interlacing of the individual fibers improves the cohesion of the fibers and thus result in an increase in the tensile strength of the non-woven web 3. In order to achieve the most uniform possible distribution of the tensile strength in the longitudinal direction, also referred to as machine direction (MD), and in cross direction, which is also referred to as CD direction, the nozzle beam 2 is guided back and forth at an amplitude so that the fluid streams 6 each produce a zigzagged structure line 10 in the non-woven web 3. The non-woven web 3 receives a linear surface structure, in which a plurality of zigzagged structure lines 10 run parallel next to each other.

FIG. 2 schematically shows a plan view of a non-woven web of the invention, which can be produced using the exemplary embodiment shown in FIG. 1. FIG. 2 schematically shows a plan view of a section of the non-woven web.

The non-woven web 3 has a linear surface structure. The surface structure is formed by a plurality of parallel structure lines 10. The surface portion of the structure lines 10 in the non-woven web forms a consolidated surface portion within the non-woven web. The regions outside the structure lines 10 represent the open surface 11 within the non-woven web. In order to achieve a minimum portion of open surface 11 of 50%, preferably 70% in relation to the total area, the structure lines 10 in the non-woven web are disposed at a distance from each other, the amplitude for moving the fluid streams back and forth when producing the strengthening effect being selected such that the points of impact produced in the non-woven web by the adjacent fluid streams do not intersect an imaginary separating line in MD direction. Arrows are used in FIG. 2 to indicate the machine direction MD and the cross direction CD.

FIGS. 3 and 4 may be referred to for the further explanation of the method of the invention and the apparatus of the invention. FIG. 3 shows a section of a lower side of a nozzle beam and FIG. 4 shows a section of a plan view of a non-woven web.

The lower side of the nozzle beam shown in FIG. 3 comprises a plurality of nozzle openings 8 disposed next to each other in a row. The nozzle openings 8 are inserted into the nozzle beam 2 such that they are disposed at a distance B from each other. Each of the nozzle openings 8 is connected to a pressure chamber, in which a fluid, preferably water, is maintained under high pressure so that a columnar fluid stream is produced from each of the nozzle openings 8. The nozzle openings 8 have a hole diameter ranging from 0.05 mm. to 0.5 mm. Depending on the hole diameters of the nozzle openings 8 and the material thickness of the non-woven web, the fluid streams are generated with a pressure gradient ranging from 30 bar to max. 600 bar.

As shown in FIG. 4, each of the fluid streams 6 results in a structure line 10 in the non-woven web 3. Three adjacent fluid streams 6 disposed next to each other are shown in FIG. 4. For strengthening the non-woven web 3, the nozzle beam 2 is guided back and forth at an amplitude substantially transversely to the running direction of the non-woven web. The letter “A” in FIG. 4 designates the amplitude, the fluid streams 6 being moved back and forth from a neutral position at the amplitude A so that the entire movement path is equal to twice the amplitude. The letter “B” indicates the distance between two adjacent fluid streams 6. In order to achieve the characteristic of a voluminous non-woven web comprising a relatively large open surface, the amplitude A of the back and forth movement of the nozzle beam 2 is adjusted in such a manner that the adjacent structure lines 10 do not intersect an imaginary separating line 15. For this purpose, the amplitude A is adjusted to a value, which does not exceed half the distance B between adjacent nozzle openings 8.

Thus, the equation A<=B/2 applies.

The distance B between adjacent nozzle openings ranges from 1 mm to 10 mm. This results in an adjustment of the amplitude for the back and forth movement of the nozzle beam in the range of from 0.5 mm to 5 mm. However, larger distances B are combined with smaller amplitudes A.

FIG. 5 shows a section of a plan view of another exemplary embodiment of a non-woven web. The surface structure in the non-woven web 3 is formed by two separately guided nozzle beams 2.1 and 2.2 each comprising a row of nozzle openings 8. The nozzle openings 8 on the nozzle beams 2.1 and 2.2 are disposed such that they are staggered in relation to each other and they each produce a fluid stream 6, which results in a structure line 10 at the point of impact on the surface of the non-woven web 3. The structure lines 10 of the fluid streams 6 are zigzagged, the fluid streams 6 being guided back and forth at an amplitude, which is smaller than the distance between two nozzle openings disposed in a row. The nozzle beams 2.1 and 2.2 move substantially in the opposite direction so that the structure lines 10 in the non-woven web 3 result in a diamond pattern. However, there are no points of intersection between the structure lines 10.

The surface structure produced in the non-woven web is substantially composed of inclined structure lines 10, which run obliquely in relation to the machine direction (MD). The degree of inclination of the structure lines 10 depends on the speed ratio between the running speed of the non-woven web 3 and the guiding speed of the nozzle beam 2. Here, it is basically possible to distinguish between two versions of the method of the invention for producing the structure lines 10 within the non-woven web 3. For this purpose, the velocity vectors VD and VB are schematically plotted in FIG. 6. With reference to the exemplary embodiment shown in FIG. 1, the identification letter VD designates the guiding speed of the nozzle beam 2. The running speed of the non-woven web 3 is marked by the identification letter VB here, which stands for the speed of the screen belt 4.

In the first case shown in the left half of FIG. 6, the speed of the screen belt 4 is adjusted to be higher than the transversely oriented guiding speed of the nozzle beam 2. The velocity vector VD and the velocity vector VB are orthogonal to each other, the length of the vector VB being of a greater magnitude. The structure line 10 produced in the non-woven web 3 with this adjustment of belt speed is indicated by the connecting line of the two vector ends. Here, an angle of inclination α, which is <45°, is adjusted between the machine direction MD of the non-woven web 3 and the structure line 10.

In order to produce a flatter structure line for strengthening the non-woven web, the guiding speed of the nozzle beam 2 is increased or the speed of the screen belt 4 is reduced. In these cases, the velocity vector VD contributes more to the resultant net vector so that the connecting line between the tips of the velocity vectors VD and VB results in a flat structure line, which develops at an angle of inclination, which is >45°. The adjustment of the belt speed or the guiding speed of the nozzle beam can thus help create structure lines for strengthening the non-woven web, which structure lines influence the strength of the non-woven web in both the machine direction MD and the cross direction CD. In principle, structure lines in an angle range of >45° result in a greater degree of strength.

If the consolidated surface regions defined by the surface structure are to achieve a magnitude of up to 50%, the line pattern of the surface structure can preferably be implemented by means of multiple-row nozzle openings within a nozzle beam, which nozzle openings are disposed in a staggered manner at a short distance from each other. FIG. 7 shows the lower side of a nozzle beam 2. Here, the nozzle beam 2 comprises closely adjacent rows of nozzle openings 8, which maintain such a staggered distance from each other that the fluid streams produced by the nozzle openings 8 contact each other and produce a wide-band structure line. It is thus possible to produce wide-band line patterns by adding other nozzle openings.

FIG. 8 schematically shows a cross-sectional view of another exemplary embodiment of an apparatus of the invention for implementing the method of the invention. The exemplary embodiment comprises a screen roller 13 as guiding means 1 for moving a non-woven web 3. The screen roller 13 is driven by means of a drive (not illustrated here) at a predefined circumferential speed so that a non-woven web 3 resting over a part of the circumference of the screen roller 13 is guided at a running speed. A gathering roller 12 and a discharge roller 14 are provided in a run-off area and in a discharge area respectively for guiding the non-woven web 3. Between the gathering roller 12 and the discharge roller 14, a nozzle beam 2 is assigned to the screen roller 13 and is held at a short distance above the screen roller 13. The lower side of the nozzle beam 2 comprises two rows of nozzle openings, through which a plurality of fluid streams 6 are produced. For this purpose, the nozzle beam 2 is connected to a fluid source by way of a fluid inlet 7. The screen roller 13 comprises a shell that is permeable to fluid so that the fluid streams produced through the nozzle openings of the nozzle beam 2 penetrate the non-woven web 3. For producing a line pattern comprising zigzagged structure lines, the nozzle beam 2 is guided back and forth in a reciprocating manner. The functioning of the apparatus for strengthening the non-woven web 3, which is guided on the circumference of the screen roller 13, is identical to that described in the aforementioned exemplary embodiments so that the preceding part of this description is incorporated herein by reference and need not be explained again below.

The exemplary embodiment of the apparatus of the invention shown in FIG. 1 and FIG. 8 is preferably operated using a liquid fluid, for example, water. However, in principle, it is also possible to use a gaseous fluid for the swirling and strengthening of the individual fibers in the non-woven web. The apparatus of the invention and the method of the invention are preferably used to produce non-woven webs, in which the surface structure forms a consolidated surface portion ranging from 5% to max. 50% of the total surface. It is thus possible to produce voluminous non-woven webs for a broad range of applications. The open surface portions of the non-woven web are thus particularly suitable for absorbing additives such as bonding agents or impregnating agents or for incorporating simple air cushions. Furthermore, the zigzagged surface structure without points of intersection of the structure lines help achieve uniform strength both in the machine direction and cross direction. Irregularities in the surface structures are avoided. In comparison with conventional rectilinear line patterns, the method of the invention enables equivalent strength with a 30%-reduced line density. It is thus possible to reduce the number of nozzle openings in relation to the width the non-woven web, thereby enabling considerable savings of energy and fluid. In one exemplary embodiment, a non-woven web was consolidated by means of a nozzle beam, which comprises a plurality of nozzle openings having a diameter of 0.12 mm. The nozzle openings were disposed at a distance of 10 mm. from each other. The nozzle beam was guided back and forth at a frequency of 75 Hz and an amplitude of 2.5 mm. The non-woven web consolidated in this manner had an open surface of <80%, the strengthened surface portions uniformly extending in the form of zigzagged structure lines over the entire surface of the non-woven web.