Water Based Coatings That Keep a Pack inside the Fibre Stream
Water-based dispersion coatings achieve food barrier requirements while maintaining full fiber repulpability and standard mill recovery yields.
Interparticle Deformation
Definitional Change
Morphological changes occur when individual latex or pigment particles change shape to fill the voids in a drying coating. This interparticle deformation is a fundamental step in the creation of a dense and non-porous surface on paper and board. It is driven by the surface tension of the evaporating liquid and the capillary pressure exerted on the particles.
Physical Mechanism
As the water evaporates, the particles are pulled together until they make physical contact. Significant interparticle deformation must then occur to eliminate the gaps between the spheres and form a continuous matrix.
Impact on Coating Quality
The extent of this movement depends on the hardness of the polymer and the temperature of the drying environment. High levels of interparticle deformation result in a smoother surface with better barrier properties against oil and water. If the particles are too rigid, they will not deform sufficiently, leading to a brittle coating that lacks structural integrity.
This process also influences the optical properties of the paper, as a more uniform film interacts with light differently than a porous one. Controlling this stage is necessary for ensuring that the final print has the desired level of gloss and ink holdout.