The influence of type and concentration of inorganic pigments on the polyurethane adhesive properties and adhesion of laminates

Abstract The introduction of white pigments into an adhesive layer is the new and economically favourable method of obtaining white laminates. In this work studies of the influence of the type and concentration of white pigments in polyurethane adhesive layer of laminates on their whiteness (opacity) and tensile strength are presented. The pigments used were titanium dioxide, zinc white and lithopone. They were added to a polyurethane adhesive in concentrations of 10–20 wt%. In order to determine the applicability of the described solution on an industrial scale, studies of viscosity, rheology and DSC thermograms of adhesives were performed as well as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) of whitened laminates and leak testing of packaging formed from these laminates. Moreover the morphology of used pigments was analysed by measuring average particle size distribution on a laser diffraction Mastersizer 2000 and on scanning electron microscopy.