Cohesive Energy
Numerical vectors representing dispersive, polar and hydrogen bonding forces describe the affinity between a polymer and various solvents. The hansen solubility parameters divide the total cohesive energy density of a substance into these three distinct molecular forces. Matching these values helps converters predict whether a resin will dissolve or disperse in a given carrier fluid.
Ink Formulation
Printing inks for flexible packaging must be carefully balanced to dry quickly and adhere firmly to plastic or paper substrates. By utilizing hansen solubility parameters, ink chemists select solvents that perfectly dissolve the binder resins without attacking the underlying polymer film. If the solvent parameters are too close to those of the film substrate, the solvent can cause the film to swell or even dissolve, causing severe deformation or block during winding.
Selecting the correct solvent mix ensures that the resin stays in solution until the drying oven, where it then deposits a smooth, uniform printed layer.
Chemical Resistance
Protective barrier varnishes must withstand exposure to various packed substances like oils, alcohols and organic acids. Designers use hansen solubility parameters to choose crosslinked polymers whose molecular forces differ significantly from those of the packed liquids. When the parameters of the barrier do not match those of the liquid, the barrier remains insoluble and maintains its integrity over the product shelf life.
This prevents the packed contents from migrating into the outer paperboard or film layers, which avoids cosmetic stains and structural softening of the package.
