Adhesive Agent
Resinous substances dissolved or dispersed in an aqueous medium provide the film forming properties and pigment carrying capacity for environmentally friendly inks. Most water based flexo binders consist of acrylic or styrene acrylic copolymers that remain stable in a high pH environment. These materials ensure that the ink adheres to the substrate and resists rubbing or scratching after the water has evaporated.
Film Development
Coalescence of the polymer particles occurs as the liquid carrier moves into the paper or is removed by forced air dryers. Selecting the correct water based flexo binders involves balancing the need for fast drying on press with the requirement for the ink to remain resoluble in the anilox cells. If the resin dries too quickly, it can build up on the printing plates and cause a loss of image detail.
High performance binders are designed to form a tough, water resistant layer once fully cured while maintaining a stable viscosity during the printing process. The choice of binder also dictates the gloss level and the chemical resistance of the final printed product.
Environmental Impact
Reduction of volatile organic compounds is the primary driver for using these aqueous systems in packaging. Because water based flexo binders eliminate the need for strong solvents, they lower the fire risk in the factory and simplify the disposal of waste materials.
