Greenfield, Massachusetts-US plastic film producer Argotec, Inc. has broadened its line of thermoplastic polyurethane (TPU) film and sheet to include flat-die-extrusion of 'hard,' or rigid polyurethane of 60D hardness.
The Greenfield-based group says this allows it to offer fabricators of film and sheet "the broadest range of flat-die-extruded thermoplastic polyurethane."
Argotec says that in making TPU film, it uses computerised mixing of resin and additives, with carefully controlled amounts of in-house regrind, if necessary, to reduce customer cost. This blend is melted, passed through the extruder and the heated material forced, under pressure, through a flat, horizontal die slit. Film gauge is controlled by regular adjustment across the die width. The film is cooled using chilled nip rolls and trimmed to width before being wound onto corrugated or plastic cores, wrapped and packaged for shipment.
Argotec says films produced via this flat-die process or the related cast-on-carrier extrusion technology are higher quality than ones made via blown film extrusion, for a range of reasons:
°They contain less gel. Gel can be unmelted resin or resin particles with slightly different melt properties. Gel can affect mechanical and aesthetic properties.
°No processing aids or lubricants are required. These processing aids can affect adhesive wet-out or interfere with downstream processing, such as lamination or printing.
°Gauge can be adjusted in-line.
°Surface finish can be controlled.
°Extremely thin films can be extruded using the cast-on-carrier option, to thicknesses as low as 0.2 mil.
°Thick films up to 125 mils can be produced.
°One or more interleafs/carriers may be used for cleanness or other reasons.
Argotec adds that, when run in its hard-wall, clean-room manufacturing facilities, flat-die extrusion "reduces virtually all contaminants, air-borne and otherwise," giving what it claims is "the cleanest possible film."