Standard Bench Viscometry Methods for Aqueous Paper Coating Emulsions
Bench viscometry of paper coating emulsions requires standardized temperature control, verified spindle geometry, and multi-shear profiling to ensure runnability.
Kaolin Clay Slurry
Rheological Control
Aqueous mineral suspension applied in paper coating color formulation provides high solids content while maintaining low viscosity under high shear conditions. Kaolin clay slurry requires precise dispersant dosing to prevent agglomeration during storage and pumping operations. Particle size distribution directly influences the rheological stability of the mixture.
Platelet morphology allows particles to slide past one another easily during blade application. Storage tanks need continuous agitation to avoid settling over extended periods.
Coating Structure
Mineral pigment deposition on the paper surface fills microscopic voids between cellulose fibers. Kaolin clay slurry improves print gloss and ink receptivity by creating a uniform leveling plane. Binder demand increases as finer particle grades present higher surface area to the latex emulsion.
Porosity control depends on packing efficiency achieved during the calendering process after drying. Caliper reduction occurs when high pressure forces mineral platelets into parallel alignment beneath the finishing rolls.
Dispersion Stability
Zeta potential measurement determines surface charge repulsion forces necessary for long term suspension stability. Kaolin clay slurry maintains negative charge values that prevent flocculation in alkaline paper mill water systems. Viscosity spikes indicate pH drift or excessive calcium ion contamination from recycled broke streams.
Temperature variations alter the hydrodynamic volume of the liquid phase during high speed metered sizing operations. Proper chemical conditioning prevents screen blinding and ensures consistent coat weight delivery across the web width.