Method for manufacturing stretchable sheet

A method for continuously manufacturing a stretchable sheet with a thread-shaped elastic body fixed between a pair of belt-shaped sheets in a state of being stretched in a direction intersecting with a conveyance direction of the belt-shaped sheets, comprising:

• a supply process of continuously feeding the thread-shaped elastic body and introducing the fed thread-shaped elastic body to elastic body winding means, wherein, in the supply process, the thread-shaped elastic body is introduced to the elastic body winding means while adjusting a tensional force thereof to constant tension with tension adjusting means which is arranged at the upstream side of the speed adjusting means and adjusting a speed of the thread-shaped elastic body with the speed adjusting means;
• a conveyance process of continuously winding the thread-shaped elastic body to a thread-conveying longitudinal structure using the elastic body winding means and conveying the wound thread-shaped elastic body in a longitudinal direction of the thread-conveying longitudinal structure;
• and
• an integration process of fixing the conveyed thread-shaped elastic body as sandwiching between the sheets,
• wherein, the elastic body winding means have a servomotor, and adjusts a winding speed of the thread-shaped elastic body by controlling a rotation speed of the servomotor, and
• in the supply process, a tensional force of the thread-shaped elastic body is adjusted to constant tension with tension adjusting means, and the thread-shaped elastic body is introduced to the elastic body winding means while adjusting a speed of the thread-shaped elastic body to be higher than the winding speed to the thread-conveying longitudinal structure with speed adjusting means which is arranged at the upstream side of the elastic body winding means and is located at the downstream side of the tension adjusting means, the thread-shaped elastic body being wound to the thread-conveying longitudinal structure by the rotation of the elastic body winding means,
• wherein the speed adjusting means comprises a feed roller arranged immediately before the elastic body winding means in a conveyance passage of the thread-shaped elastic body, guide rollers and a servomotor for rotating the feed roller, the feed roller being disposed between the guide rollers, so that the thread-shaped elastic body is continuously supplied to the elastic body winding means through the feed roller and the guide rollers and the speed of the thread-shaped elastic body is adjusted by increasing or decreasing a rotation speed of the feed roller by the servomotor for rotating the feed roller,
• wherein the thread-shaped elastic body is led out from a bobbin, and a length of a conveyance passage of the thread-shaped elastic body after leaving from the feed roller until being introduced to the elastic body winding means is in a range of 10% to 50% against a total length of the conveyance passage of the thread-shaped elastic body from the bobbin to the elastic body winding means,
• wherein, in the supply process, a tensional force of the thread-shaped elastic body is adjusted with tension adjusting means which is arranged at the upstream side of the speed adjusting means, and the tension adjusting means includes a tensor to apply tension to the thread-shaped elastic body with braking, a take-off roller located at the downstream side of the tensor and a tension measuring unit and adjusts tension of the thread-shaped elastic body by increasing or decreasing a rotation speed of the take-off roller based on a detection output from the tension measuring unit,
• wherein the speed of the thread-shaped elastic body introduced to the elastic body winding means is set to be in a range of 110% to 120% of the winding speed to the thread-conveying longitudinal structure, and
• wherein the stretching ratio of the thread-shaped elastic body with tension adjusted by the tension adjusting means in a stretchable sheet to be manufactured is in a range of 1.5 to 4.0.