Strengths
In reality, commercial print providers need a combination of technologies to stay competitive.
This ink instantly gels on contact with media, resulting in precise dot gain and positional control, perfectly repeatable images, and instantly cured, durable prints. The state-of-the-art, low-temperature light-emitting diode (LED)-UV curing system moves independently from the printing carriage to enable uniform, post-print UV curing, which contributes to print speed and quality. Confident unattended printing and roll change, and automated quality assurance help to reduce print waste and significantly contribute to overall productivity.
Limitations
UV gel systems bridge the gap between 1625-mm (64-in.) eco-solvent and latex systems with 3.04-m (10-ft) UV and latex production machines. As such, they are ideal for helping to increase the productivity and cost of operation for users of the former and flexibility for shorter runs and media versatility of the latter. That said, these printers may not be ideal for providers who have limited large-format print volume.
Key applications
- point-of-purchase (POP)/promotional signage;
- floor graphics, stickers, and repositionable graphics;
- backlit displays;
- interior decorations and wallcoverings; and
- fleet graphics.
Latex inkjet printing in large-format
Latex and resin-based inks have increased in popularity over the last several years. These ink systems use water as the main ingredient, but the carrier for the pigments is either latex or resin-based.
Printers using these types of inks also need built-in heaters so the media becomes receptive to the ink for adhesion and enables the ink to dry properly. Latex is said to offer equal or improved performance compared to solvent ink for printing on vinyl (polyvinyl chloride [PVC]), as well as printing onto paper, fabrics, polyester, and polyethylene—substrates which solvent technology is known to struggle with.
The latex ink, which is water-based with a polymer that is bonded to the substrate by heat, does not need air purification or solvent extraction. It is also odourless, making it suitable for a range of indoor applications where solvent machines are not. The output is promised to have an unlaminated exterior life of three years. Another advantage claimed over solvent is the print is dry and can be finished and mounted straight from the printer without requiring the outgassing period. However, as the printer uses a built-in, heat-based curing and drying system to ensure the output exits the equipment completely dry, it increases the print time.
Strengths
Since the inks are water-based, there is no need for extra ventilation to remove any harmful substances emanating from the printer. The water-based formulations of latex inks reduce the impact of printing on the environment. They produce durable printing for outdoor and indoor applications. Additionally, prints also look excellent for signage applications.
Limitations
Latex printers require preprint and post print heaters to cure the media, resulting in higher energy consumption compared to other inkjet technologies. Some substrates may buckle under the higher temperatures needed to cure the ink onto the substrate.
Slow speed may also become a bottleneck for certain applications as adequate heating/curing must occur in-line, variable with media type and coverage.
Key applications
- promotional signage;
- floor graphics, stickers, and repositionable graphics;
- backlit displays;
- interior decorations and wallcoverings; and
- vehicle wraps.
UV-based flatbed printers in large-format
UV-curable printers, unlike aqueous or solvent printers, use ink where the carrier is not evaporated and the ink does not dry—it is cured using ultraviolet light after printing.
UV-curable inks “dry” as soon as they are cured, can be applied to a wide range of uncoated substrates, and produce a very robust image. That said, these materials are considered expensive and require costly curing modules in the printer. Though improvements are being made in the technology, UV-curable inks (because of their capacity and heaviness) are somewhat susceptible to cracking if applied to a flexible substrate. As such, they are often used in large “flatbed” printers, which print directly to rigid substrates such as plastic, wood, or aluminum where flexibility is not a concern. However, these inks are being used more often in “hybrid” printers to print onto vinyl and other flexible media traditionally associated with solvent printing.
The colourants in UV-cured inks can be dye or pigment-based. The latter is more common; however, because of its greater light fastness and durability. Pigments used in outdoor advertising and display applications have similar requirements to those used in automotive paints.
Strengths
UV printing does not require coated media, resulting in cost savings on many materials. UV-curable ink dries (cures) almost immediately and is very durable outdoors. These inks can print onto just about any substrate, including foam board, wood, cardboard, glass, vinyl, and many others.
Limitations
UV inks are less conformable to media that stretches such as vinyl for vehicle wraps. As it does not dry flat on the media, a perfectly dried printed image will have a matte look. While UV printers have made great strides in the past several years, they are still not comparable to solvent, or, in some cases, latex printers in this respect. High quality UV printers can also be more expensive than roll-to-roll systems.
