Patent ID: 6984276
Filing Date: 2006-01-10
Classification: D04H,Y10T

Abstract:
1. A method for modifying the ratio of machine-direction and cross-direction orientation in nonwoven webs which comprises the steps of: providing a substantially non-bonded nonwoven web having an initial direction of highest fiber orientation, the web comprising about 5 to 40 weight percent of a first fiber component and about 95 to 60 weight percent of a second fiber component, the first fiber component consisting essentially of multiple-component fibers capable of developing three-dimensional spiral crimp upon heating and the second fiber component consisting essentially of fibers which do not develop spiral crimp upon heating; and heating the substantially non-bonded nonwoven web under free shrinkage conditions to a temperature sufficient to cause the multiple-component fibers to develop three-dimensional spiral crimp, the heating temperature being selected such that the heat-treated nonwoven web remains substantially non-bonded during the heating step and to cause the substantially non-bonded nonwoven web to shrink by at least about 10% in the initial direction of highest original web orientation, wherein the nonwoven' web further has a surface speed and wherein the free-shrinkage heating step comprises the steps of: conveying the substantially non-bonded nonwoven web on a first conveying surface having a first conveying surface speed; transferring the substantially non-bonded nonwoven web from the first conveying surface through a transfer zone to a second conveying surface, the second conveying surface having a second conveying surface speed; the substantially non-bonded nonwoven web being conveyed through the transfer zone free of contact with the conveying surfaces; conducting the heat treatment in the transfer zone, causing the web surface speed to decrease as the web is conveyed through the transfer zone a result of crimp development of the multiple-component fibers; and transferring the heat-treated substantially non-bonded nonwoven web to the second conveying surface as the web exits the transfer zone, the second conveying surface speed being less than the first conveying surface speed.