General-Purpose Inks vs. Specialty Inks

At Sericol we continually monitor the trends in the screen printing marketplace. One such trend that has come under debate is the increased use of specialty inks rather than general purpose inks.
In the following article, Mitch Bode, marketing director for Sericol, discusses the reasons behind this trend and how your particular screen printing business can benefit.
There has indeed been a trend away from "general purpose" inks to ink formulations that perform better on a more narrow band of substrates or applications, particularly within the specialty category (including: compact disc, roll label, container decorating, etc.). The driving force behind this trend is the specific product performance requirements demanded by printers in certain markets. As an example, compact discs are printed on highly automated equipment at a very rapid rate (50 to 70 discs per minute), so ink cure speeds must be very fast. This rapid cure could pose difficulties in general graphic printing, because cure controls are less precise.
In addition, CD inks must be somewhat thixotropic so they don't flow through the mesh when the CD decorator is idle, yet they must flow out smoothly, once on the disc. This would not allow them to be printed easily on more conventional graphic-printing equipment. Conversely, many general graphic inks are not suitable for CD applications as many graphic formulations contain raw materials that adversely affect the polycarbonate disc and may cause distortion of the digitized data on the disc. And, as mentioned earlier, the viscosities of the graphic inks are different. They typically are not "short" enough to prevent drip-through on the automated CD printer, resulting in a mess that consumes valuable production time to clean up.
Another good example: Different weathering or light fastness requirements exist in the long-term decal (O.E.M. and fleet) market as compared to the P.O.P. market. Obviously, P.O.P. inks do not require the same weathering capability, since most applications are short-term exterior and/or interior. Obviously, the higher grade pigments used in a long-term decal ink are more costly than those pigments normally used in a P.O.P. ink, and most P.O.P. printers would not want to bear this increased cost. Even within applications such as P.O.P., there are a variety of substrates ranging from rigid plastics, like fluted polyolefins and styrene, to highly flexible materials like static cling vinyl and vinyl banners.
With the raw materials currently available to the screen-ink manufacturing community, it is not possible to formulate a single ink that will adhere to this broad band of stocks and provide the performance criteria desired. Different resins are required to gain adhesion to certain substrates which, in turn, require different solvents to solubilize these resins and result in multiple specialized formulations.
In summary, I think the best analogy to this situation is the woodworking tool - The Shopsmith. According to ads, the Shopsmith is a drill press, it's a lathe, it's a table saw, and yes, it is even a sander. And although I am confident the ads are true and the Shopsmith performs all these functions, I am equally confident that the discerning woodworker would prefer to use an individual tool designed for a specific function rather than a "multi-purpose" tool that may compromise the quality of the end product. Like the discerning woodworker, screen printers are becoming more specialized and demanding of ink and process performance. This demand will continue to drive the trend toward specialty inks for specific applications.