As we continue to look at various products and applications, we need to understand the technologies that facilitate these types of manufacturing tools and processes. In Part 1 of this discussion, we looked at different printhead technologies and how they work. However, the key to all of this is increasingly the characteristics of the inks, fluids, and other materials that are deposited onto a surface with those printheads to create the final product. While bespoke and hybrid manufacturing processes could require other deposition materials, for this article we will look at ink for printing, and, more specifically, packaging.

When most people think about ink, they immediately focus on color, and that is one of the primary components and uses. However, that alone really doesn’t begin to address the most important features of the ink: its ability to adhere smoothly to the material surface. It all starts by getting the ink through the printhead nozzles, then to the surface of the material (paper, plastic, metal, etc.) with accurate positioning, but it doesn’t stop there. Once the ink is deposited on the surface, the real fun begins: how do you get it to adhere to and dry on that surface? And, by the way, it would really be nice if it didn’t rub off, too!

Of course, we can’t really talk about ink without speaking about the media. Binding the ink to the paper is not only a key factor in ensuring the print stays on the surface of the paper without wicking into the paper, and it also has a significant effect on the look of the print itself. If we are printing on nonabsorbent flexible packaging materials, it’s even more of a challenge. There is a balance between having the ink dry quickly on the media to allow for a wider range of media use and possibly increased imaging speed, but not so fast that it dries in the head, which can then create print and maintenance issues. Drying the inks faster can also reduce the amount of heat required to dry the paper, which reduces energy costs and allows the paper to stay flatter for further finishing, etc.