Unless you’ve been out of the market for the past year or two, it’s no surprise that solvent inkjet printing systems have rapidly built a position as the technology of choice for outdoor vinyl banners. What might be surprising is the availability of a full assortment of media and substrates for applications other than banners. Unfortunately, early claims about the ability of solvent inks to print on uncoated media have left many owners of solvent systems dazed and confused about what can and cannot be achieved. The following is intended to clear away some of the confusion and highlight what one leading media supplier is doing to keep pace with the rapidly changing hardware market.
Solvent or Water-based?
The difference? Simply put—evaporation. Inkjet print heads use tiny plumbing. As a result, the amount of pigment in inkjet ink is relatively low, and the amount of carrier fluid, or vehicle, is high, at least compared to other printing techniques. Too much pigment, and the tiny plumbing in the print head clogs. Over the past 15 years, there have been huge strides to create water-based pigment inks that wouldn’t clog, printers with supplemental dryers to speed up evaporation, and coated media that would quickly absorb the carrier fluid to enable prints to be dry-to-the-touch in seconds. However, low solids and high vehicle are still a requirement. And nothing changed the laws of physics, meaning the rate of evaporation remains governed by temperature and humidity.
Enter solvent. In the 90’s, inkjet technologists sought to replace water as a vehicle by substituting organic solvents, which are various kinds of alcohols, ketones, ethers, and esters that evaporate much faster than water. Again, huge strides were made to create the right balance of fast evaporation, shelf-stability, compatibility with print heads, and many other factors. Accompanied by some now famous false starts, the technologists got it right. Low solids and high vehicle are still a requirement. But, the solvents evaporate faster, allowing for faster printing, faster drying, and improved productivity.
What does this have to do with vinyl banner? Perhaps intended by the technologists, or perhaps a happy accident, the solvents that gave the right balance of ink properties also had the ability to partially dissolve or soften poly-vinyl-chloride polymers. As a result, the pigments in the ink were found to stick quite well to uncoated vinyl. This, combined with the fact that most solvent ink printers are open systems which allow for lower ink costs, led to a much lower cost of production for outdoor scrim banners and signage. The buying public caught on, and quickly.
Solvent or Eco-Solvent?
While much distinction has been made between the two, from a chemistry standpoint, they’re not so different. Some inks are formulated with very fast evaporating solvents, many of which have strong odors. Aside from an unpleasant smell, the odor makes it very apparent that there’s solvent in the air after it evaporates. For all the obvious reasons, ink formulators have worked hard to replace the smelly solvents with other kinds of ketones, ethers, and esters that are less odiferous. They’ve succeeded, usually giving up a little bit in the rate of evaporation, and sometimes giving up a little in the ability of the ink to soften vinyl to allow for the use of a wide variety of uncoated vinyl choices. The ketones, ethers, and esters still evaporate into the air, but it’s less apparent to those working near the printers.
Media: Land of Confusion
So what happened to the promise of prints on any uncoated media? In some cases, it has proven valid, but with conditions attached. The early adopters failed to say or hear that vinyl is a generic term referring to hundreds, if not thousands, of chemical recipes that determine the properties of vinyl sheet goods. Some vinyls can be so soft as to pucker and distort in contact with strong solvents. Other vinyls can be so hard as to not give adequate pigment adhesion, especially as the ink moves toward the eco-formulations. What’s left is a much narrower range of products that work reliably with your printer, and a narrower performance window that will produce high-quality, sellable output.
Recognizing the Role of Media Producers
Rapidly changing technology, coupled with optimism about lower cost of output via lower cost media, results in adjusted expectations and uncertainty about what to buy and who to buy it from. Rapid adoption of solvent machines able to print scrim vinyl and self-adhesive vinyl results in increased competition for outside jobs, lower prices, and lower margins.
Sihl saw the challenge and is working to improve the lot of the solvent printer operator.
As a pioneer in the inkjet media industry, Sihl was one of the first to market with outdoor, waterfast media for aqueous inkjet. It was also one of the first to feel the impact on its scrim and self-adhesive vinyl business as a result of solvent. Phillip Kidd, regional manager for Sihl in the Southwest, began to see the solvent opportunity in 2003. His feedback to the factories was a contributing factor in Sihl’s launch of its Solvit family of solvent-compatible media. This media replicates the application fields well-established with water-based inks, opening up immense market opportunities for solvent printer owners wrestling with falling prices for vinyl output.
Not content to be able to offer solvent specialties, Kidd championed the notion that the uncoated vinyl market was crying for a stable, well-known, and well-trusted source of supply. For many reasons, the world production of vinyl-chloride monomer—raw material for vinyl—and vinyl sheet goods is in Asia. Supply chains are long and unpredictable, and quality consistency can be uncertain.
After a test-market in which its North American sales team acted as sales agent for a generic line of uncoated vinyl, Sihl concluded that, in addition to consistent quality, the market seeks to buy vinyl for solvent printing from a well-known, well-established, and dependable supplier. By far, the people best positioned to do this are the very people that have served the market from its inception—the media manufacturers—whether Sihl or any of the other trusted brands. After a considerable search for supply that would be of consistent quality, Sihl launched its own brand of uncoated vinyl under the SureSolv family name.
Aside from surety of supply, and confidence that the products will work in the widest range of solvent printers, Sihl’s dealers and distributors are happy to be able to combine all their media purchases, whether solvent or aqueous, into a single purchase order.
The decision to supply to market products not produced in one of its own factories was not a decision taken lightly. Kidd credits the broader vision to Diego Mosna, owner of the Diatec Group and acquirer of Sihl’s operating assets in November, 2003.