Method for sealing an inner bag to an outer container

Abstract

A process for forming, handling, affixing, and inverting a thin plastic half bag to a continuous inner side wall of an outer plastic container. A non-metallic mandrel is used as a tool for thermoforming a half bag over the top of the mandrel. The top of the mandrel with bag attached is inserted into an open end of the outer plastic container. A continuous stripe of heat-activated adhesive containing metal particles is bonded to the exterior of the half bag at the open end of the half bag. When the half bag is inserted, the stripe of adhesive is positioned near the midpoint of the container. A magnetic induction field generated near the container midpoint heats the metal particles in the heat-activated adhesive, thereby activating the adhesive. When the adhesive has been heated, compressed air is blown from the mandrel to press the bag and adhesive against the inner side wall of the outer container to cause bonding between them. After the field is removed and the adhesive cools, the mandrel is withdrawn from the thin plastic bag. Vacuum applied to the closed end of the bag from the top of the mandrel causes the bag to be inverted to the open end of the container as the mandrel is withdrawn.