| abstract |
A highly stretched film has permanently heat-sealed edges that are nearly invisible. A folding apparatus folds the edge portions of a film to form folded edges. The folded film then is passed through a bridle mechanism having two heated rolls. A series of nips apply pressure to the folded film as it is heated by the heated rolls. The nip pressure, combined with the heat imparted by the heated rolls, causes thermal welding of the folded edges resulting in permanent heat-sealed edges. Because the film edges are folded prior to the hot-stretching, the hot stretch process performs dual functions of stretching the film and heat sealing the folded edges. The resulting stretched film has permanently heat-sealed edges that do no separate, and which prevent tearing of the film edges during subsequent processing and use. |