Flexographic Aqueous Latex Barrier Coating Viscosity Measurement Fundamentals
Flexographic aqueous latex barrier coating viscosity requires multi-shear rotational measurement to ensure accurate anilox transfer and barrier film continuity.
Brookfield Viscometer
Rotational Rheometer
Laboratory instruments of this class measure the internal friction of fluids by spinning a spindle at a defined speed through the medium. Operators use the brookfield viscometer to analyze liquid coatings, starch adhesives, and polymer emulsions before application on paperboard. This device determines resistance to flow by measuring the torque required to rotate the submerged element.
Instrument Mechanics
A calibrated spring connects the motor drive to the spindle, which comes in various shapes such as discs or cylinders to match the viscosity range of the fluid. Liquid drag against the spindle creates a torque that deflects the spring, and a transducer translates this movement into a viscosity value. This mechanism operates at multiple discrete speeds to characterize fluids that change flow behaviour under shear force.
In starch formulation for corrugated board, the motor turns the spindle at low speeds to measure structural build, then accelerates to simulate high-shear pumped delivery. These readings dictate whether the mix requires further dilution or enzyme treatment.
Industrial Utility
Maintaining the correct fluid thickness on a high speed coating line prevents defects like skipping or ribbing on the paper surface. When liquid coatings are too thick, the pump lines experience excessive pressure and the coating head applies an uneven layer. Checking viscosity with this rotating spindle test ensures that the mixture behaves correctly under the high speeds of the blade coater.