High Speed Ink Liquid Interface Dynamics in Ultra Light Coated Virgin Hardwood Graphic Papers
Ultra-light coated virgin hardwood papers demand sub-50nm coat pore radii to balance high-speed inkjet solvent absorption against hardwood fiber swelling.
Pigment Filtration Kinetics
Dewatering Rate
Water separation from a wet coating color occurs as the fluid is applied to an absorptive paper web. The term pigment filtration kinetics refers to the rate at which a dense filter cake of pigment particles builds up at the paper boundary during this dewatering phase. This process controls the thickness and uniformity of the applied coating layer.
Filtration Mechanism
Rapid migration of water into the paper pores leaves a highly concentrated layer of pigments and binders on the surface of the moving sheet. In pigment filtration kinetics research, the rate of water immobilization depends on the drainage resistance of the forming filter cake and the hydraulic suction of the base paper. A fast dewatering rate can create a dense, dry skin that prevents further water escape, leading to uneven coating distribution and blade streaks on the coater.
Understanding these kinetics helps mill engineers optimize formulation solids and viscosity.
Coating Quality
Coating operators adjust binder levels and water retention aids to maintain a balanced dewatering profile across the press. When pigment filtration kinetics are too fast, the coating color loses its fluidity prematurely, causing runnability problems and poor blade metering. Correct filtration speeds ensure a smooth, level coating with uniform binder distribution and excellent surface strength.