This article discusses defects that may possibly occur during production of film on calendaring equipment as well as the sources of black spots, their detection, evaluation and possible means of prevention.
The article was written by Andreas Schnabel (works in the filed of metrology and process technology at Klochner Pentaplast GmbH & Co KG, Montabaur, Germany; and Oliver Hissmann (employed by OCS GmbH, Witten, Germany).
Pharmaceutical products are packaged in plastic blister packs around the world. Every customer expects that the film used satisfies increasingly stringent requirements. In addition to economy, hygiene, protection in different climates and atmospheres, this also means a guarantee of maximum safety for the product packaged in compliance with new and ever more demanding requirements.
The monolayer film that is produced primarily on calendaring equipment is converted into blister packs or serves as the substrate for high-quality coatings and laminates. These calendered monolayer films are plasticizer-free rigid PVC films that are manufactured in various thicknesses and colours. They can be classified into three product groups: With their good thermoforming characteristics and their good chemical resistance, homopolymer films are well suited for production of standard blister packs. For demanding blister geometries or maximum processing speeds, copolymer and high copolymer films offer greatly improved flow characteristics.
A reprint of the paper from Kunstoffe international 7/2007, is available on request from Rheology Solutions by quoting OCS-007