Stretchable composite sheet

1. A stretchable composite sheet comprising a stretch sheet and a nonstretch sheet laminated with the stretch sheet and having a first direction and a second direction perpendicular to the first direction,

the stretch sheet having a first zone with elastic stretchability and a second zone with less elastic stretchability than that of the first zone, the first and the second zones extending in the first direction and alternate in the second direction,

the stretch sheet and the nonstretch sheet being bonded to each other on their facing sides,

the stretchable composite sheet as a whole having stretchability in at least the second direction, and

the stretchable composite sheet having, in a natural, relaxed state, a large number of ridges extending in the first direction on the nonstretch sheet side in a portion where the stretch sheet and the nonstretch sheet are bonded to each other over substantially the entire area;

wherein a pitch of the ridges is 0.5 to 5 mm and a height of the ridges is 0.5 to 5 mm;

wherein the stretch sheet comprises an extensible nonwoven fabric and a large number of elastic filaments bonded to the nonwoven fabric in their substantially nonstretched state over the whole length thereof, the elastic filaments being arranged to extend in the same direction without intersecting with each other, and the stretch sheet having stretchability in the direction in which the elastic filaments extend;

wherein the direction in which the elastic filaments extend is perpendicular to the first direction;

wherein the stretchable composite sheet has second ridges that protrude on the opposite side of the ridges and on the side that the nonstretch sheet is not bonded; and

wherein the second ridges extend in the same direction as the ridges, are formed between the ridges that the second ridges are adjacent to, and are shorter than the height of the ridges.

2. The stretchable composite sheet according to claim 1 , wherein the stretch sheet has a width retention of 70% to 100% with respect to the width before the stretch when stretched 2.0 times in the second direction.

3. The stretchable composite sheet according to claim 1 , wherein the stretch sheet is obtained by stretching a precursor sheet of the stretch sheet between a pair of intermeshing toothed surfaces each having alternate ridges and grooves to form the first and the second zones in the precursor sheet.

4. An absorbent article comprising the stretchable composite sheet according to claim 1 .

5. The absorbent article according to claim 4 , which is a pull-on type absorbent article comprising an absorbent body and an exterior cover which is disposed on the garment-facing side of the absorbent body and to which the absorbent body is secured,

wherein the exterior cover is formed totally or partly of the stretchable composite sheet.

6. The stretchable composite sheet according to claim 1 , wherein the elastic filaments are in a substantially nonstretched state at the time of bonding to the nonwoven fabric.

7. The stretchable composite sheet according to claim 1 , wherein the stretch sheet is obtained by stretching a precursor sheet of the stretch sheet; and

wherein the precursor sheet comprises webs of the nonwoven fabric that are inextensible.

8. The stretchable composite sheet according to claim 1 , wherein the elastic filaments are fixed to the nonwoven fabric in their substantially nonstretched state.

9. The stretchable composite sheet according to claim 1 , wherein the elastic filaments are formed by drawing a filamentous elastic resin in a molten or softened state;

wherein the molten or softened elastic filaments are sandwiched between a first layer of the nonwoven fabric and a second layer of the nonwoven fabric that are unrolled and fed at equal speeds; and

wherein the sandwiched elastic filaments are taken off at a predetermined speed that is equal to the feed speed of the first and second layers of the nonwoven fabric.

10. The stretchable composite sheet according to claim 1 , wherein the stretch sheet is obtained by stretching a precursor sheet of the stretch sheet in the direction in which the elastic filaments extend while being passed between a pair of intermeshing toothed surfaces each having alternate ridges and grooves.

11. The stretchable composite sheet according to claim 10 , wherein regions of the precursor sheet are thinner because the regions are pressed radially.

12. A process for producing a stretchable composite sheet comprising a stretch sheet and a nonstretch sheet laminated with the stretch sheet, having a first direction and a second direction perpendicular to the first direction, and having in its natural, relaxed state a large number of ridges all over the area or in at least part of the nonstretch sheet side thereof, the stretch sheet having a first zone with elastic stretchability and a second zone with less elastic stretchability than that of the first zone, and the first and second zones extending in the first direction and alternate in the second direction,

the process comprising bonding the stretch sheet and the nonstretch sheet to each other via an adhesive while the stretch sheet is in its stretched state such that the two sheets are bonded on their facing sides over substantially the entire area of a portion where the large number of ridges are to form;

wherein a pitch of the ridges is 0.5 to 5 mm and a height of the ridges is 0.5 to 5 mm;

wherein the stretch sheet is obtained by stretching a precursor sheet of the stretch sheet between a pair of intermeshing toothed surfaces each having alternate ridges and grooves to form the first and the second zones on the precursor sheet;

wherein the stretch sheet is bonded to the nonstretch sheet while the stretch sheet is in a stretched state;

wherein the stretch sheet comprises an extensible nonwoven fabric and a large number of elastic filaments bonded to the nonwoven fabric in their substantially nonstretched state over the whole length thereof, the elastic filaments being arranged to extend in the same direction without intersecting with each other, and the stretch sheet having stretchability in the direction in which the elastic filaments extend;

wherein the elastic filaments are formed by drawing a filamentous elastic resin in a molten or softened state;

wherein the precursor sheet comprises webs of the nonwoven fabric that are inextensible; and

wherein a large number of elastic filaments extruded from a spinning nozzle are fusion bonded to the nonwoven fabric before solidifying while being drawn at a predetermined speed and oriented in one direction without intersecting with each other in order to form the stretch sheet.

13. The process for producing a stretchable composite sheet according to claim 12 , wherein the stretch sheet is bonded to the nonstretch sheet while the stretch sheet is in a state stretched 1.1 to 4.0 times in one of the machine direction and the cross machine direction.

14. The process for producing a stretchable composite sheet according to claim 12 , wherein the adhesive is applied to a coating weight of 0.5 to 20 g/m 2 .