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Ink and media are linked because neither serves a purpose without the other. A recent trend in solvent ink technology has been the development of eco-solvent and mild- or light-solvent ink—more "human friendly" versions of traditional solvent ink. This shift has had an impact on specialty media manufacturers who craft coatings optimized for the ink used in solvent printers. The drivers of change in the ink industry stem from a desire to make work environments healthier and to reduce the cost of environmental compliance. To that end, new technology exists on a limited basis today whereby "bio-based" green chemistry is being used to create solvent ink based on corn and soy. Stay tuned on this front.
Eco-solvent ink may have looked like just another fad, but it's a direction that has gained momentum. Virtually all printer manufacturers and many third-party ink makers offer a variant of eco-solvent ink. The attractiveness of this ink is in its solvent-like performance without the strong smell or ventilation requirements of solvent ink. The latest generation tend to have low VOCs (Volatile Organic Compounds), contains no cyclohexanones (a suspected neuro- and inmuno-toxin), and does not require extensive ventilation systems.
Two of the target markets for eco-solvent printers are the small print-for-pay providers and in-plant/corporate users currently utilizing aqueous inkjet technology. The ink can bridge the gap for these users who may not have the capital to rework their space for full-solvent ink printers. With the capacity to print onto a wide variety of coated specialty and uncoated vinyl based substrates, the ability to deliver outdoor-durable prints, and the flexibility to be installed in more accessible locations, these printers hold a lot of promise for an expanding group of digital print providers.
Solvent Inks
All of the OEM hardware manufacturers have optimized their printers and ink towards PVC (polyvinyl chloride) vinyl-based materials such as banner vinyl or adhesive-backed vinyl. This is why approximately 90 percent of the media consumed in solvent printers is vinyl based. The development of specialty media for these printers had initially been limited because, for many years, solvent printers were used primarily for outdoor signs and billboards. These applications did not require high resolution, photo-like quality. The stage is set today for a broader range of non-PVC based specialty media as hardware prices are dropping, print head resolution is approaching that of aqueous printing technology, and ink has a broader color gamut plus ever-increasing environmental friendliness. These recent innovations enable solvent technology to be used for some of the indoor "photorealistic" applications—such as POP advertising signage—that were served by aqueous inkjet technology.
Specialty media offers the ability to expand product portfolios to higher value-added materials and improve the up-time of underutilized solvent printer capacity by increasing applications beyond vinyl signage. This can also increase the profitability of service bureaus that charge for the solvent prints they make.
With the new reach of eco-solvent printers potentially replacing wide-format aqueous printers, we expect to see an increased demand for a greater variety of specialty substrates. And as you might expect, as ink changes, so will the coatings or treatments applied to the specialty base materials.
Specialty Media
Solvent ink is designed to provide high durability and to adhere strongly to vinyl. The chemical composition of the ink (the solvent part) dissolves the vinyl and enables the color particles to bond with the material, creating a tough yet flexible image. For the ink to properly adhere to non-vinyl substrates such as paper, polyester films and textiles, the substrates need to have some form of an ink receptive coating applied. Much of the initial specialty media for solvent were simply aqueous media converted into a format that fit in the solvent printer and performed adequately with solvent ink. The price points were high and images were often dull, lacking the color "pop" and resolution of aqueous prints. The expectation in the market is that the cost for a solvent printed sign will be significantly less than the same sign created using aqueous technology. The current gap in media value and performance has opened up new areas of specialty substrate development. Like aqueous technology, solvent specialty media needs to keep pace with the evolution of solvent ink, but today still lags in the range of specialty product offerings and widths that are currently available for aqueous technology. As printers with the next generations of solvent ink continue to replace wide-format aqueous printers, the specialty media under development will most likely be geared towards high-end, high value-add applications such as backlit displays and closely viewed photorealistic signage.
- Photopaper: A review of ten solvent printer manufacturers and media distributors show that, on average, each carries two different types of photopaper in two or three different widths. If aqueous history is any teacher, over the next few years the offerings will expand to include different price points, gloss levels, and thicknesses (calipers). These photopapers will most likely still have to be overlaminated for extended indoor or outdoor use.
- Different gloss levels: Most of the available solvent photo papers currently include a satin finish. Developments in a high gloss finish which generates greater color "pop" can be expected. Satin, luster, and semi-gloss finishes will continue to be popular for reducing glare for prints displayed in areas with bright, direct lighting.
- Different thicknesses: Current products vary with thicknesses ranging between 6 and 8 mil. Thicker products will reduce the need to adhere the print to rigid backers in order to prevent curling or flexing when used in "drop-in" frames.
- Matte papers: Matte papers will have expanded offerings as a lower cost alternative to photopapers.
- Backlit Films: There is currently a limited selection of backlit films available for solvent printers—a few offerings on polyester film and the more traditional translucent vinyl. The challenge is to generate photorealistic images with enough color density for solvent printed material to be used in the most demanding applications—retail/POP and airport backlit signage. A variety of calipers and matte vs. gloss backlit films will be required to fill the range of end-user requirements.
- White Films: These films will be a quality extension of pressure-sensitive vinyl and glossy papers for use in close-viewing situations and for trade show graphics. The base material is typically a 5- to 10-mil polyester (mylar) with a high gloss finish that is capable of generating photorealistic images with exceptionally high color gamut. Some pressure-sensitive glossy vinyls are capable of achieving extremely high resolution even if they do not have the rigidity and stability of a polyester base. These films are self-supporting, somewhat rigid and are better suited for freestanding or hanging displays.
- Clear Films: Clear or translucent films have been limited for signage applications until white ink was introduced. Now, a clear cling or low tack adhesive-backed PVC for window graphics is a good match for solvent printers. Using these printers to create overlays and color separations will demand higher base material clarity, rigidity, stability, and improved color densities.
- Canvas: Although not the choice of most digital fine artists, canvas has filled a niche in commercial art applications where the digital reproduction quality of solvent printers is acceptable. Since most of the giclée print sites are extremely conscious of the negative impact that solvent ink, odors, and disposal can have on their businesses, it's likely that until this objection is overcome, solvent art reproduction will be limited to production facilities capable of dealing with solvent effluence as opposed to the boutique giclée print shop. Still, solvent canvas is available today in a range of weights and compositions such as cotton, polyester, and cotton / polyester blends.
The arrival of friendlier solvent ink combined with lower cost, higher resolution solvent printers has opened up opportunities for applications beyond vinyl signage. At the same time, specialty media requiring an ink receptive coating have adapted to the new ink chemistries in order to achieve the quality performance that the added value of coating brings to the substrate. With this technology, the ink is still anticipated to do most of the work. That is certainly true with printing on vinyl. However, if vinyl is not the media of choice for your printing applications, a growing range of solvent print media is available today that are can meet the market requirements for signage, photo applications, art and beyond.
Dan Halkyard is Director of Marketing for Océ Imaging Supplies. Andreas DeGroot, Display Graphics Product Manager for Océ Imaging Supplies, also contributed to this article. For additional information, visit www.oceusa.com/imagingsupplies.
author: BY DAN HALKYARD