Drawn, temporarily meta-stable, laminated thermoplastics, shrink film - prepd. by combining profiled film, flat intermediate film and shrink film into a laminate with air pockets

摘要

Mfr. of a 3-ply, shrink film laminate suitable for packaging impact-sensitive merchandise comprises combining a shrink film with another film lamina to define air cushions, in such a way that, simultaneous with the application of a covering film lamina, the 2 three-plies are bonded together by rollers. A shaping roller under vacuum is used for mfr. of the air cushion film. Plastics are melted and extruded through a nozzle to form a film, on the shaping roller. The vacuum causes the film to closely hug the configuration of the roller surface. Similarly, the melt is extruded from the nozzle to form a second film which is combined, in flat film shape, with the profiled film on the roller. This combination is facilitated by a resiliently supported pressure roller at the point of contact of the two laminae. A pre-stressed shrink film, mfd. in known manner, is hauled off another roller and conveyed, in cold state, to the pressure roller and laminated, without shrinking, to the covering film, at still at 150 degrees C hot. The resulting 3-ply laminate is then hauled off the shaping roller. Polystyrene, polyethylene etc. are suitable plastics, for this process.