High Shear Rheology Calibration Procedures for Aqueous Latex Anilox Evacuation
Calibrating capillary rheometers with Bagley and Mooney corrections ensures precise aqueous latex transfer from anilox cells, preventing spatters and excess coat weight.
Cone and Plate Rheometer
Viscometric Instrument
Rotational measurement devices evaluate fluid viscosity and viscoelastic properties under precisely defined shear fields. A cone and plate rheometer consists of a shallow conical spindle rotating above a flat stationary plate, establishing an invariant shear rate throughout the intervening fluid gap. In coating preparation for paper and packaging, the instrument measures flow characteristics of pigment slips, starch adhesives and functional barrier emulsions across wide shear rates.
The angular clearance between cone and plate remains microscopic, usually between one and four degrees. This specific geometry ensures that fluid situated near the central apex experiences identical deformation rates to fluid circulating at the outer perimeter.
Shear Geometry
Controlled shear rate profiles generated within the narrow test gap separate thixotropic recovery from shear thinning phenomena. When analysing mineral coating slurries, a cone and plate rheometer records viscosity across deformation ranges spanning one reciprocal second up to several thousand reciprocal seconds. Modern instruments use Peltier temperature stages to hold test temperatures within narrow bounds, avoiding measurement errors caused by viscous heating during high-speed rotation.
Normal force sensors mounted along the vertical drive shaft measure elastic normal stress differences generated by associative thickeners and latex networks under rapid displacement.
Viscosity Boundary
Coating formulations containing coarse mineral particles or unrefined fibre fragments cause test artefacts inside narrow gap rheometers. If pigment agglomerates exceed one tenth of the gap height between spindle and plate, jamming events distort torque readings and produce false dilatant spikes. Sample evaporation during testing alters solids content in open atmospheres, requiring solvent traps to preserve data integrity across extended measurement cycles.
A cone and plate rheometer provides foundational flow data for blade and curtain coater designs.