Customisation and optimisation of high-barrier laminates using simulation models
Permeation through the inorganic layers in laminates mainly occurs via defects. These defects arise during the production and cannot be wholly avoided. A thin layer of lacquer between two inorganic layers with defects results in a low stationary permeability.
However, if the lacquer layer is thicker and has a high solubility coefficient then the time required for a substance to permeate through the laminate is very long. This time can be several months and in some cases even many years.
Lacquers are used in high-barrier laminates for technical applications such as vacuum insulation panels (VIPs), organic photovoltaic (OPV) systems, and organic light emitting diodes (OLEDs). The laminates often consist of alternating inorganic layers (e.g. SiOx, Al, AlOx) and organic lacquer layers. The lacquer layers planarize the inorganic layers and seal the defects.
Simulation of permeation of oxygen and water vapor through an inorganic layer with defects and permeable matrix on a polymer substrate. (Source: Oliver Mesbauer, Fraunhofer IVV)
In his doctoral thesis entitled “Analytical and numerical calculations on the barrier performance of multi-layer structures” Dr. Oliver Miesbauer from the Fraunhofer Institute for Process Engineering and Packaging IVV describes the theoretical basis and key experimental findings for manufacturing high-barrier laminates.
The results of this work are being used by the Fraunhofer Polymer Surfaces Alliance POLO to develop high-barrier laminates and will also be available in the future to project partners of the Fraunhofer IVV.