Polypropylene Pop Quiz

On in-line laminators, curl is a huge issue directly related to polypropylene elongation during lamination. Converters can adjust the tension on the laminating web to make a flat web, so that register is not affected, and can adjust laminating tension to compensate for curl. In extrusion lamination, the softening point of polypropylene is 180°F, and the laminating extrudate's melt temperature ranges from 590°F to 620°F. Converters must favor the chill roll to eliminate softening or stretching of the more sensitive film.