Shirred elastic sheet material

A method for manufacturing a bag comprising:

• providing a first side wall;
• providing a second side wall, the second side wall joined to the first side wall to define a closed bottom end and an open top end;
• providing a retaining element;
• and
• attaching a portion of the retaining element to one of the first and second side walls adjacent the top end to thereby define an attached portion and an unattached portion, the retaining element continuously attached such that the retaining element extends longitudinally between the first and second side ends a predetermined length, the attached portion comprising a substantially continuous attachment.

A method of continuous production of shirred, elastic, flexible sheet sections capable of rapidly assuming a relaxed condition after being tensioned, the method comprising the steps of:

• providing a continuous web of thermoplastic sheet material;
• advancing the web of thermoplastic sheet material along a machine direction path;
• providing a continuous strip of heat-shrinkable elastomeric material having a pair of spaced apart side edges separated by a width, the strip being shrinkable in the machine direction;
• continuously attaching at a first station the strip of heat-shrinkable elastomeric material to the web as it is being advanced along the path, the resulting affixed strip having at least one side edge portion left unattached to the web;
• separating the web with the attached strip of heat-shrinkable elastomeric material into individual sheet sections at a second station;
• and
• exposing at a third station the sheet sections to an activation temperature for a time duration sufficient to shrink the unattached edge portions of the heat-shrinkable elastomeric material strip so as to cause a desired shirring of the sheet section.

A shirred, elastic, flexible article, comprising:

• a sheet of thermoplastic material;
• at least one strip of heat-activated elastic film material adapted to shrink and become elastic in a lengthwise direction upon exposure to heat above an activation temperature;
• said strip of heat-activated elastic film material having a width dimension;
• a seal between said thermoplastic sheet and said heat-activated film material, said seal being continuous in the lengthwise direction of said strip and further defining said width dimension of said strip of heat-activated elastic film as having a sealed portion and at least one unsealed side edge portion;
• whereby
• heat activation of said article results in the lengthwise shrinkage of said at least one unsealed side edge portion sufficient to provide a desire shirring of the thermoplastic sheet material adjacent said zone of attachment.