METHOD AND APPARATUS FOR THE REDUCTION OF THE SAG AND/OR OF THE VARYING STRESS PROFILE OF A FLATTENED TUBULAR FILM WEB PRODUCED BY BLOW MOLDING

摘要

The invention refers to a method for the reduction of the sag and/or of the different stress profile of a flattened tubular film web produced by blow molding and made of thermoplastic synthetic resin, transversely to its longitudinal direction. For the solution of the problem to provide a method of said kind according to which the sag and/or the different states of tension transversely to the tubular film web can be easily reduced or eliminated to a maximum degree, the tubular film web is heated along its width and then cooled and/or stretched. Furthermore, the invention refers to an apparatus for carrying out said method.