Chemical Adhesion
Synthetic binders containing functional carboxylic acid groups improve the binding strength of paper coating formulations. Using carboxylated polymers enhances the adhesion between pigment particles and cellulose fibers, forming a stable matrix. This chemical modification increases the resistance of the coated sheet to high-temperature offset printing.
Formulation Function
The presence of polar groups along the molecular chain creates strong hydrogen bonds with the hydroxyl groups on the fiber surface. In formulation, carboxylated polymers interact with inorganic pigments to regulate the viscosity and water retention of the liquid coating before application. This interaction prevents the coating from drying too quickly or penetrating too deeply into the porous base sheet.
Coating Performance
Coatings must withstand the intense mechanical shear of the blade application process without coagulating or showing runnability defects. Low-shear environments do not disrupt these polymers, but high-shear forces require carefully controlled molecular weight distribution to prevent rheological failure on the coater. The resulting layer provides a smooth surface that ensures high ink transfer accuracy during subsequent printing runs.
Because of this, chemical manufacturers design these additives to balance runnability, water resistance, and final dry strength. This control ensures the polymer does not re-emulsify when exposed to moisture during storage.
