Printing systems have continued to develop as new printing methods that adapt to different materials have become popular over the last few decades. These advancements have also led to the evolution of printing inks for the variety of printing systems that have become available.
Solvent inks were introduced to the market with solvent inkjet printers. However, the inks were deemed aggressive and harsh because of their high VOC (volatile organic compounds) content. Solvent inks are recommended for outdoor signage use, such as banners and shop boards because of the strong fumes that they release. Another con of solvent inks is their corrosive oil-based solution which often clogs the printheads of the inkjets. Nonetheless, they are sunlight and rain resistant, which eliminates the need for a laminate to be used.
Eco-solvent inks were introduced into the market in the early 2000’s to replace solvent inks. These inks have a much lower VOC content, which makes them less harsh than solvent inks. The low VOC content also allows for indoor applications to be used for store branding and posters. The chemicals in the eco-solvent inks don’t attack the inkjet printheads as aggressively as solvent inks do but they often require a laminate to be applied if they will be displayed outdoors.
UV and UV-LED Inks are the latest advancement in inkjet printing systems that have begun to emerge. UV inks can be inkjet printed on a wide variety of porous and non-porous material and are cured using ultraviolet light. Once the UV ink is exposed to the UV light, the liquid in the ink quickly turns into a solid, permitting very little evaporation to occur and minimal absorption of the ink into the paper stock.
UV-LED inks on the other hand use LED lamps to cure the ink instead of mercury lamps, which avoids the extreme heat of mercury lamps. UV-LED inks allow for an even wider range of printing substrates to be used because the heat in LED lamps is significantly reduced, which helps to avoid overheating of the actual substrate while printing. UV-LED inks do have a higher cost than standard UV inks because of the special photoinitiator and formulation in the ink. The LED lamps have a very low energy consumption and they can also last much longer than mercury lamps used in standard UV inks.