Patent ID: 7258758
Filing Date: 2007-08-21
Classification: B32B,D04H,Y10T

Abstract:
1. A method for producing a high loft, low density nonwoven web, the nonwoven web having X, Y and Z dimensions, with the X dimension being in a machine direction, the Y dimension being in a cross machine direction and the Z dimension being in a loft direction, comprising, in order: a) forming a group of crimpable, substantially continuous, spunbond, bicomponent fibers of A/B configuration and depositing the group of fibers onto a forming surface without the addition of heat to the fibers before deposition; b) first heating the fibers at a time and a temperature sufficient to induce a relaxation of molecular orientation of one side of the fiber while controlling or minimizing the forces which tend to impede crimping of the fibers whereby the fibers are allowed to crimp in the Z-direction with no more than a non-functional bonding of the fibers; c) after the first heating, cooling the group of fibers below the temperature where the fibers will bond to each other and thereby inducing the fibers to crimp while controlling or minimizing the forces which tend to impede crimping of the fibers whereby the fibers are allowed to crimp in the Z-direction to produce the high loft, low density nonwoven web on a forming wire, the nonwoven web having a top side, a top side formation index, a wire side, and a wire side formation index such that the top side formation index differs from the wire side formation index by less than about 11%; and d) bonding the crimped fibers of the high loft, low density nonwoven web in a manner to substantially maintain its high loft using a pattern of point bonds covering not more than 25% of an area of the nonwoven web.