The Basics of Flexo Printing Inks Explained

1. How Flexographic Printing Inks Work Flexographic printing —often shortened to “Flexo” — is one of the most widely used printing methods for packaging, labels, bags, cartons, films, and many other materials. The technique stands out for its flexibility, speed, and ability to print on a wide variety of surfaces, from paper and cardboard to plastic films and metallic foils. A central element of this process is the inks used, and understanding how they work helps explain why Flexo remains so popular across industries. What Makes Flexo Different: The Printing Process The printing machine works as follows: ink is transferred from an ink— a precisely engraved roller with microscopic cells — which meters a controlled amount of ink. A doctor blade often scrapes off excess ink, ensuring only the right quantity remains in the cells. What Are Flexographic Inks — Types & Composition “Flexo printing inks” come in different formulations depending on the substrate and end-use requirements. The common types include water-based inks, solvent-based inks, and UV- curable inks. Water-based inks are often used for paper, cardboard, and other absorbent substrates. They use water (sometimes with small additions of alcohol or glycol ethers) as the vehicle for pigments, binders, and additives. Water-based inks are popular for their lower environmental impact and suitability for packaging and corrugated materials. Solvent-based inks use volatile organic solvents (such as certain alcohols or esters) as the carrier. These inks are particularly suited for non-porous substrates like plastic films, foils, or laminated surfaces, where rapid drying and strong adhesion are required. UV-curable inks (and sometimes EB-curable) remain liquid until they are exposed to ultraviolet (or electron-beam) energy, at which point a chemical reaction hardens the ink into a solid film. These inks are used when instant curing, high gloss, or scratch resistance is needed — especially on sensitive substrates or in high-speed production lines. Where Flexo Inks Are Commonly Used Because of their flexibility and adaptability, flexographic inks are widely used for printing on a variety of materials: Paper, cardboard, corrugated board — for cartons, packaging boxes, labels Plastic films, foils, laminated substrates — for flexible packaging like bags, wrappers, pouches, and multilayer packaging Labels, tapes, wrappers, disposable items — where quick turnaround and high volume are required.

2. Because Flexo can handle both porous and non-porous materials, and because inks can be tailored (water-based, solvent-based, UV), the method remains a workhorse for packaging and large-scale printing needs How Flexo Inks Dry or Cure Drying or curing is a critical part of the Flexo process — especially important because printing often happens at high speeds. The mechanism depends on the ink type: With water-based or solvent-based inks, drying occurs mainly through evaporation: the liquid vehicle (water or solvent) evaporates, leaving pigment and resin behind on the substrate. For plastic films or non-absorbent substrates, quick evaporation is necessary; otherwise, the ink might smear or not adhere properly. UV- or EB-curable inks dry (cure) when exposed to the appropriate energy (light or electron beam), which triggers polymerization and hardening. This results in a durable, stable ink film almost immediately, which is beneficial for fast roll-to-roll production. Conclusion Flexographic printing inks play a crucial role in how the Flexo process achieves consistent, high- speed results across different materials. Their low-viscosity formulations allow the ink to flow smoothly and transfer efficiently during printing, while modern drying and curing systems ensure quick and stable results. Whether water-based, solvent-based, or UV-curable, each type of ink is designed to meet the needs of specific substrates and printing requirements.