Managing variables associated with the substrates you use is critical to quality. Find out how to work with some popular, but picky, materials.
A common thing would be using the wrong inks or clear coats that would fade before seven years. Ours last over the long haul, but we’re careful in selecting them. Another problem might be adhesion failure caused by applying a substrate to a dirty truck. Using a substrate in the wrong climate could be another disaster.
When printing on polycarbonate, be sure to choose the correct type of UV bulb. Printing with UV ink systems requires the right UV bulb to maintain the integrity of critical colors without shifting the color readings or degrading the substrate on multiple pass jobs. There are better bulbs for curing—mercury or iron, for example—but on multiple-pass jobs or parts with critical colors, gallium bulbs work well. We will not use the mercury or iron bulbs on grays or other critical colors or on jobs with more than five colors. Polycarbonate can become brittle and/or yellow when over exposed to certain UV wavelengths, so consult your ink supplier for a recommendation on
the best way to cure a particular ink system.
Any market that can use the high-ly aesthetic virtues of a polycarbonate overlay is our best market. Polycarbonate is used in the medical, automotive, appliance, and OEM markets with great success. Velvet-textured polycarbonate is a very popular substrate for its durable, anti-glare, smudge-resistant surface finish. Applications include decorative logos, warning and safety decals, and low-use (low number of actuations) customer interfaces and control panels.
Not fully curing your inks, solvent or UV, can cause headaches for production down the line. Applying adhesives too soon after printing UV inks can cause issues with delamination as the ink and the adhesive interact. We recommend waiting approximately 24 hours before applying an adhesive.
We do screen and digital printing for banners, P-O-P displays, transit advertising, and a wide variety of projects. One growing area is printing on polycarbonate (Figure 9). When printing on polycarbonate, one thing to keep in mind is how it is used—decorative displays, panel fronts for electronic equipment, etc. Nine times out of ten, the image is subsurface printed and then laminated with adhesive. Pick your inks wisely, and let your ink manufacturer in on what type of adhesive you use.
You must be sure the inks you use can adhere well enough to the substrate so they will not give way when you apply the adhesive. In other words, if you pull on the panel and the polycarbonate lifts off—leaving ink and adhesive behind—you have a disaster! Unfortunately, the problem is hard to detect immediately. This type of failure occurs over time. The adhesive laminate sometimes breaks down the adhesive properties of the ink. You have to work closely with the adhesive and ink manufacturer to prevent this problem.
Selecting a matte finish for the subsurface-printed side of the polycarbonate sometimes helps prevent the problem. It gives more tooth for the adhesive to grab. Solvent inks tend to adhere better than UV inks, but solvent inks are more difficult to work in this application. Environmental concerns are also a problem.
OEMs—companies that once used metal for long-term durability in markings and control panels—present a large market for polycarbonate substrates. Polycarbonate gives the customer a wide variety of surface finishes. It is less expensive than metal substrates to mass-produce.
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