Zoned stretching of a web

Abstract

An apparatus and methods for stretching one or more zones of an anisotropic web and anisotropic webs including one or more stretched zones is provided. Each of the stretched zones in the web is stretched in the cross-web direction, i.e., the direction transverse to the down-web direction. The stretching can be performed continuously as the web is advancing through the apparatus in the down-web direction. The method for stretching an extensible web in the cross direction generally is practiced on a substantially continuous, extensible anisotropic web. The cross web stretching occurs in an orientation zone established by an orientation unit. The orientation unit moves the web out of the plane of the web where the web is under tension, but without any side restraints. The web moves over the orientation unit where the degree of orientation is proportional to the cross direction displacement of a portion of the web by the orientation unit. The anisotropic web has a tensile strength in the downweb direction greater than the cross direction such that the web is preferentially displaced in the cross web direction by the orientation unit. This can be a downweb direction tensile strength at least 50 percent greater than the cross web direction.

1 . A method of orienting a web in a cross machine direction comprising, providing an anisotropic web having a width dimension and a substantially continuous length dimension, the web having a strength in the length dimension greater than in the width dimension 
 placing the web along a downweb web path under tension less than that needed to elongate the web in the downweb direction,    moving a section of the web in the width dimension out of the web path with an orientation unit having a diversion device, while maintaining the web under tension along the downweb web path, so that at least a section of the web is elongated in the width dimension.    
   
   
       2 . The method of orienting a web in a cross machine direction of  claim 1  wherein the web is unrestrained on either side of an orientation zone when in the orientation unit.  
   
   
       3 . The method of orienting a web in a cross machine direction of  claim 2  wherein the web has a strength in the downweb direction at least 50 percent greater than in the cross direction.  
   
   
       4 . The method of orienting a web in a cross machine direction of  claim 2  wherein the web has a strength in the downweb direction at least 100 percent greater than in the cross direction.  
   
   
       5 . The method of orienting a web in a cross machine direction of  claim 2  wherein the web comprises a nonwoven web or web layer.  
   
   
       6 . The method of orienting a web in a cross machine direction of  claim 5  wherein the web is a laminate of an elastic layer and at least one nonwoven layer.  
   
   
       7 . The method of orienting a web in a cross machine direction of  claim 6  wherein the web the elastic layer is a film layer.  
   
   
       8 . The method of orienting a web in a cross machine direction of  claim 2 , wherein the web has high strength longitudinal zones defining an orientation zone of relatively lower strength web wherein the web is preferentially orientated.  
   
   
       9 . The method of orienting a web in a cross machine direction of  claim 2  wherein the orientation unit has a degree of diversion of from 1 to 100 cm.  
   
   
       10 . The method of orienting a web in a cross machine direction of  claim 2  wherein the orientation unit has a degree of diversion of from 5 to 20 cm.  
   
   
       11 . The method of orienting a web in a cross machine direction of  claim 2  wherein the orientation unit has a diversion path with an incline angle, from the start of diversion of the web from the web path to an apex of the diversions device, of from 5 to 80 degrees.  
   
   
       12 . The method of orienting a web in a cross machine direction of  claim 11  wherein the orientation unit has an incline angle of from 20 to 50 degrees.  
   
   
       13 . The method of orienting a web in a cross machine direction of  claim 2  wherein the diversion device is a wheel.  
   
   
       14 . The method of orienting a web in a cross machine direction of  claim 2  wherein there are multiple orientation units located in the downweb direction of the web.  
   
   
       15 . The method of orienting a web in a cross machine direction of  claim 14  wherein the downweb orientation units are aligned to orient at least in part the same cross sectional zone of the web.  
   
   
       16 . The method of orienting a web in a cross machine direction of  claim 14  wherein the downweb orientation units are displaced to orient at least in part different cross sectional zones of the web.  
   
   
       17 . The method of orienting a web in a cross machine direction of  claim 2  wherein there are multiple orientation units located in the cross web direction of the web.  
   
   
       18 . The method of orienting a web in a cross machine direction of  claim 14  wherein the orientation unit diversion device is a wheel having a variable apex's to provide variable degrees of cross web orientation in the downweb direction in a single orientation zone.  
   
   
       19 . An apparatus for orienting a web in a cross machine direction the apparatus comprising, 
 a web path having width dimension and a tensioning device in the downweb direction,    and an orientation unit on a portion of the web path having a diversion device for diverting a web out of the web path wherein there are no restraining devices for holding down opposing sections of the web on either side of the orientation unit.    
   
   
       20 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein the orientation unit has a degree of diversion of from 1 to 100 cm.  
   
   
       21 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein the orientation unit has a degree of diversion of from 5 to 20 cm.  
   
   
       22 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein the orientation unit has a diversion path with an incline angle, from the start of diversion of a web from the web path to an apex of the diversions device, of from 5 to 80 degrees.  
   
   
       23 . The apparatus for orienting a web in a cross machine direction of  claim 22  wherein the orientation unit has an incline angle of from 20 to 50 degrees.  
   
   
       24 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein the diversion device is a wheel.  
   
   
       25 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein there are multiple orientation units located in the downweb direction of the web path.  
   
   
       26 . The apparatus for orienting a web in a cross machine direction of  claim 25  wherein the downweb orientation units are aligned along the web path.  
   
   
       27 . The apparatus for orienting a web in a cross machine direction of  claim 25  wherein the downweb orientation units are displaced along the web path.  
   
   
       28 . The apparatus for orienting a web in a cross machine direction of  claim 19  wherein there are multiple orientation units located in the cross direction of the web path.  
   
   
       29 . The apparatus for orienting a web in a cross machine direction of  claim 24  wherein the orientation unit diversion device is a wheel having a variable apex's to provide variable degrees of cross web orientation in the downweb direction.