Stretchable composite sheet and process for forming the same with a plurality of gathers
Here is disclosed a composite sheet comprising substantially non-stretchable nonwoven fabric sheets and a plurality of elastic members extending in a transverse direction and spaced one from another in a longitudinal direction by a given spacing wherein the elastic members are secured in a stretched state to the nonwoven fabric sheets. The composite sheet has a plurality of gathers formed by slightly undulated surface of the nonwoven fabric sheets and the elastic members and these gathers are substantially continuous in the longitudinal direction and arranged at substantially regular intervals in the transverse direction.
1. A stretchable composite sheet having a first direction and a second direction intersecting said first direction, comprising substantially non-stretchable sheet members and a plurality of elastic members extending in said first direction spaced one from another by a given spacing in said second direction wherein said elastic members are secured in a stretched state to said sheet members, said composite sheet further comprising: a plurality of gathers formed by alternately undulated ups-and-downs of said sheet members and said elastic members, and said gathers being substantially continuous in said second direction and spaced one from another by substantially uniform spacing in said first direction.
2. The stretchable composite sheet according to claim 1 , wherein the maximum height of said gathers from troughs to crests thereof as measured in regions containing said elastic members is lower than the maximum height from said troughs to said crests as measured in regions between respective pairs of the adjacent elastic members and wherein the crests and the troughs of said gathers slightly undulate in said second direction.
3. The stretchable composite sheet according to claim 2 , wherein profiles connecting the crests and the troughs of said gathers show generally circular arcs in said first direction.
4. The stretchable composite sheet according to claims 1 , wherein said sheet members comprise a pair of fibrous nonwoven fabric sheets overlaid each other with said elastic members interposed between these nonwoven fabric sheets.