If developing a sustainable graphics-printing process is a goal for your business, consider how the latest generation of UV-curable screen inks can help. This discussion looks at the history of UV inks, recent ink-formulation developments, and ways you can increase productivity while helping to reduce carbon dioxide emissions.
Renewable resource Replacing petroleum-based raw materials is the first area to evaluate. At this time there are very few acrylate-based UV raw materials that are based on renewable resources. The few that do exist do not enhance the performance of UV-curable inks. Small amounts could be safely added to existing formulations, but how much would be gained?
When considering the ink and substrate combined, the renewable raw material represented by the ink film would be less than 1% of the total material (ink + substrate) that the final graphic comprises. However, this could change as newer raw materials become available. Ink manufacturers continuously evaluate the use of renewable resources.
Water could also be used in UV inks. This is not new technology and is found widely in Europe. The downside is that this hybrid ink is limited in use to paper and a few plastics. The paper or porous material allows the water to be pulled into the paper, which makes it possible for the UV materials to cure properly. On non-porous materials, water-based UV inks would first need to be heat dried to remove the water and then UV cured. If the water is not removed first, the UV reaction is retarded, which results in poor ink adhesion.
This type of hybrid ink not only slows down production but also consumes more energy in the drying process. In addition, water-based UV inks require very careful processing and good environmental controls related to humidity. When humidity is not controlled, print and curing properties will vary as the water evaporates from the ink during a print run.
At this time, it is very difficult to change the formulation of UV inks to use renewable resources; the ink requires the use of oligomers, monomers, initiators, and pigments to provide proper adhesion, desired print and color characteristics, blocking resistance, flexibility, durability, etc. Renewable alternatives for these various materials do not exist at this time.
Recycling Once an ink is dried (solvent or water) or cured (UV), the ink film is 100 % solids and considered non-hazardous for waste disposal. This film needs to satisfy specific criteria for storage, shipping, display for a certain amount of time, resistance to various indoor or outdoor conditions, and disposal. So breaking down the ink for recycling or biodegrading runs counter to its desired performance characteristics.
Did you enjoy this article? Click here to subscribe to the magazine.