Pilot-scale demonstration of novel tandem coating process: Combining dispersion and extrusion coating with enhanced barrier properties

Increasing environmental and legislative demands have accelerated the development of new packaging materials and processes toward more sustainable alternatives. Furthermore, barrier properties of the packaging have become increasingly important, as food waste creates environmental problems. Nowadays, multilayer structures are typically used to create required barrier properties to the packages. The aim of the study was to combine dispersion and extrusion coating into consecutive tandem process to produce two-layer structure with enhanced barrier properties. By combining two processing steps into one, time and resources are saved. The study presents demonstration of the tandem coating in pilot-scale. The process was tested with several different materials and combinations and the processing conditions were optimized to produce optimal layer structure and properties. The properties of samples were analyzed with microscopy imaging, pinhole measurement and barrier measurements including oxygen, water vapor and grease permeation. Single layer of dispersion coatings could not produce continuous film, but the extrusion coatings filled the pinholes and enabled low permeation values. The permeabilities of the tandem coated structures were promising and generally lower than the sum of two individual layers. Moreover, the tandem coated structures produced with sustainable alternatives, performed better than traditional materials in oxygen and grease permeation measurements.