Composite sheet and method for manufacturing the same
A composite sheet having an elastic layer and an inelastic layer and high breathability and a method for manufacturing such improved composite sheet. The composite sheet includes an elastic layer and an inelastic layer joined and laminated through a plurality of joints. The elastic layer is formed with first depressions overlapping the joints and extending in a transverse direction and first protrusions. Interior space if the first protrusions is filled with constituent fibers of the elastic layer. The inelastic layer is formed with second depressions overlapping the joints and extending in a longitudinal direction and second protrusions. Along the second depressions, the elastic layer and the inelastic layer come in contact with each other at the joints and, along the second protrusions, the inelastic layer is spaced from the elastic layer to define clearance gaps in these layers.
1. A composite sheet having a longitudinal direction and a transverse direction being orthogonal thereto and including an elastic layer defining a first surface and being elastically stretchable and contractible at least in the transverse direction and an inelastic layer defining a second surface wherein the elastic layer and the inelastic layer are joined to each other, wherein:
the elastic layer and the inelastic layer are joined to each other at a plurality of joints spaced from each other in the longitudinal direction as well as in the transverse direction, said joints including interface portions of the elastic and inelastic layers;
the elastic layer comprises a combination of elastic fibers and inelastic fibers and has a plurality of first depressions overlapping the joints and extending in the transverse direction and a plurality of first protrusions being adjacent to the first depressions, respectively, and extending in the transverse direction; and
the inelastic layer comprises a combination of elastic fibers and inelastic fibers and has a plurality of second depressions overlapping the joints and extending in the longitudinal direction and a plurality of second protrusions being adjacent to the second depressions, respectively, and extending in the longitudinal direction,
wherein the first surface of the composite sheet is opposite the second surface of the composite sheet and first protrusions project in an outward direction from the first surface of the composite sheet and the elastic fibers and inelastic fibers of the inelastic layer extend above and below a line drawn through the interface portions of the joints, and the second protrusions project in an opposite outward direction from the second surface of the composite sheet,
the first surface of the composite sheet and the second surface of the composite sheet are outer surfaces that are on opposite sides of the composite sheet,
each of said first protrusions have a length and a width, with the widths being shorter than the lengths, and the lengths of each of the first protrusions extend in the transverse direction,
each of said second protrusions having a length and a width, with the widths being shorter than the lengths, and the lengths of each of said second protrusions extend in the longitudinal direction, and
the elastic layer having a fiber density whereby after the first protrusions are flattened they return to their original non-flattened state.
2. The composite sheet according to claim 1 wherein the elastic layer and the inelastic layer are respectively formed of a fibrous nonwoven fabric containing a thermoplastic resin and the elastic layer and the inelastic layer are welded to each other at the joints.
3. The composite sheet according to claim 1 , wherein, at the second protrusions, the inelastic layer is spaced from the elastic layer to form clearance gaps therebetween.
4. The composite sheet according to claim 1 , wherein the elastic layer is at least partially put in contact with the inelastic layer at the first protrusions.
5. The composite sheet according to claim 1 , wherein a plurality of the joints are arranged so that these joints are distanced from each other in the transverse direction along each of imaginary lines extending in the transverse direction and the joints arranged on each pair of the adjacent imaginary lines are out of alignment in the longitudinal direction.
6. The composite sheet according to claim 1 wherein, in a wearing article including a skin-contact surface and a non-skin-contact surface opposite thereto for the article wearer and a chassis having front and rear waist regions and a crotch region, at least one of the front and rear waist regions is formed of the composite sheet.
7. The composite sheet according to claim 2 , wherein, at the second protrusions, the inelastic layer is spaced from the elastic layer to form clearance gaps therebetween.
8. The composite sheet according to claim 2 , wherein the elastic layer is at least partially put in contact with the inelastic layer at the first protrusions.
9. The composite sheet according to claim 3 , wherein the elastic layer is at least partially put in contact with the inelastic layer at the first protrusions.
10. The composite sheet according to claim 7 , wherein the elastic layer is at least partially put in contact with the inelastic layer at the first protrusions.