Method and apparatus for strengthening a running non-woven web, and a non-woven web

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.

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.