Optimizing Solids and Rheology in Blade Coating Using Pigment Blends
Authors*: Guillermo Bluvol
Dr. Michael Kässberger
Franz Reichhart
Producers of coated papers are badly looking for any measure that
might contribute to overall production cost reduction. In most of the
cases the pigment system has already been optimized for the target
optical properties.
In the case of glossy grades, the use of 100% ultrafine calcium
carbonate (GCC) is currently European state-of-the-art technology.
Although needed for high sheet gloss development, ultrafine
carbonates restrict the upper limit of solids content affordable
for trouble-free blade runnability. Furthermore, the resulting very
fast ink setting of these pigments associated with low binder level
or inappropriate latex type often affects printability (backtrap
mottling, print gloss).
The work in hand aims to explain the significant impact of pigment
fineness on rheology and hence the final solids content of the coating
color. The effect of blending a suitable coarse GCC fraction into the
ultrafine pigment is described and practical results presented.
*Authors’ references:
Omya, Research & Technology Services, CH-4665 Oftringen, Switzerland
Corresponding author: Guillermo Bluvol – E-mail: [email protected]
References
O PAPEL vol. 72, num. 11, pp. 55 – 59 NOV 2011
