Organosolv lignin as a filler in inks, varnishes and paints

The effect of the addition of organosolv lignin (OL) on the rheological behaviour of different inks, varnishes, paints and vegetable oils was studied. It was found that the viscosity of the OL-filled suspensions increased linearly with increasing OL content up to a volume fraction of 0.10 and thereafter increased sharply and obeyed Krieger-Dougherty's law. The effect of OL on the elastic and viscous moduli followed the same trend. The intrinsic viscosity of OL and the maximum volume fraction which could be incorporated into ink vehicles, varnishes and paints were found to be about 3 and 0.55, respectively. The misting of these viscous liquids was drastically reduced by adding modest quantities of OL. Thus, for a commercial varnish at 50 degreesC, the addition of about 10% w/w of OL reduced its misting by 87%. All these positive effects were reached without affecting the drying kinetics of the ensuing coatings. (C) 2003 Elsevier Science B.V. All rights reserved.