Voltar   

Optimizing Solids and Rheology in Blade Coating

Artigos Técnicos | Artigos Técnicos | 27.11.2011




Optimizing Solids and Rheology in Blade Coating Using Pigment Blends - Part 1

Authors*: Guillermo Bluvol
Dr. Michael Kässberger
Franz Reichhart

The paper industry has long known the potential advantages of
running the highest possible coating solids from both a quality and
economic standpoint. The limiting factor has always been blade
runnability and coat weight control. The excellent rheology of
calcium carbonate (GCC) has traditionally been used to increase the
maximum solids level, but even with high levels of this material the
coating solids becomes quite demanding when very/ultra fine types
are used to produce glossy grades.
Work has been done using lab and pilot coater trials to evaluate
the influence of pigment shape, size and particle size distribution on
the upper solids limit of a coating formulation. The major impact of
pigment packing once all other components in the formulation are
optimized is theoretically characterized.
A numerical model has been developed to describe and
better visualize the influence of GCC particle size on the
maximum volume fraction of the dispersed pigments. A simple
but effective concept of blending a suitable coarse GCC
fraction into the matrix of the fine host pigment is described
and practical results presented.

*Authors’ references:
Omya, Research & Technology Services, CH-4665 Oftringen, Switzerland
Corresponding author: Guillermo Bluvol - E-mail: guillermo.bluvol@omya.com