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.
Binder Migration Kinetics
Physical Movement
Transport phenomena describe the movement of adhesive polymers through a coating layer during the drying phase of paper production. Binder migration kinetics determine how fast these materials move toward the surface or the base sheet as heat is applied to a wet coating. The speed of this process depends on the evaporation rate and the rheology of the coating color.
Drying Rate
High temperatures in the drying section accelerate the flow of liquid toward the surface of the paper. This movement carries dissolved or suspended polymers along with it. If the evaporation happens too quickly, the binders concentrate at the very top of the coating layer.
Such a distribution creates a dense skin that blocks ink solvents during printing. Slower drying allows for a more even settling of the solid components throughout the thickness of the coating.
Print Quality
Surface concentration of binders leads to mottle or uneven ink absorption during offset printing. A lack of binder at the base-coating interface causes picking or coating delamination under the stress of high-tack inks. Adjusting the drying profile manages the velocity of the liquid phase to prevent these defects.
Proper control balances the energy input against the chemical properties of the latex or starch used in the formulation. This balance ensures that the finished surface maintains a uniform distribution of pigments and binders for consistent ink reception.