By Cassandra Balentine
Packaging represents a major opportunity for print service providers (PSPs) looking to expand into new markets. For those with wide format UV printing capabilities, packaging applications are a consideration.
Features inherent to UV LED and UV-curable inks—including immediate dry time and enhanced adhesion characteristics with many types of media, further the availability of extended color gamut, especially white—add value to packaging applications.
PSPs with UV printing capabilities should weigh the benefits and challenges of utilizing the technology for packaging applications.
Above: The Canon Oce Arizona 6100 High Flow Vacuum Series is ideal for corrugated packaging material.
UV Advantages
As previously noted, UV-based inks provide a variety of advantages, which translate well to package printing.
“Going back to the early days of UV inkjet—before 2000—it was all about getting the ink and printhead to work together reliably so that the integrators could build some hardware around the printhead. Today’s ink must cure faster, respond to pinning, run in quicker systems, reliably print with smaller droplets, work in high frequency printheads, be compatible with new media types, and the list goes on. So inks have changed a lot in composition and they are produced to ever higher specifications and tighter tolerances,” shares Phil Jackman, global product manager, digital, Sun Chemical Corporation.
He points to a variety of advantages of UV inks including instantaneous dry time, excellent printhead open time, high productivity, reduced printhead maintenance intervals and longer life, reliable jetting, wide media compatibility, inherent adhesion performance, wide color gamut, proven ink technology, reduced energy consumption compared to drying of water-based inks, and compatibility with heat-sensitive-media—especially UV LED cured.
“One of the biggest advantages of UV inks for digital packaging is the substrate versatility, often without use of a primer,” says Mike Barry, product marketing manager, Fujifilm North America Corporation, Graphic Systems Division.
Juan Kim, CEO, Valloy Incorporation, agrees, adding that UV inks bond to various packaging substrates strongly these days, for both flexible and rigid applications. Furthermore, special color inks like white, varnish, silver, or fluorescent are available.
White ink is another advantage. “White ink opens up the possibility of printing on surfaces that range in color. PSPs working with a packaging workflow can utilize white to print on non-white surfaces, including metallic foils,” agrees Michael Maxwell, senior manager, Mimaki USA, Inc.
Deborah Hutcheson, director of marketing, Agfa Graphics, believes digital UV package printing is more cost effective, offers faster turnaround, and reduces overhead with just-in-time inventory. “There is no need to warehouse thousands of boxes when a PSP can print the job and ship it out immediately.”
“The ability of UV inkjet printing on corrugated is lucrative because PSPs can produce prototypes quickly and efficiently, or they can print corrugated and end caps for one account with hundreds of locations across the country,” continues Hutcheson. She adds that brands are also leveraging secondary packaging—the corrugated displays and the store end cap—as a way to increase their messaging. “Brands are driving more customization and more personalization on the package itself, which lends itself to a short-run digital UV printing process.”
Patrick Donigain, senior marketing specialist, Canon Solutions America, says UV is also durable and resistant to scratching, fading, and water. “As a result of these properties, it’s a relatively simple transition from printing signage to printing on corrugated boxes and temporary displays.”
Curing Considerations
The dry time of UV inks is one of its biggest advantages. With the use of UV and UV LED lamps, output printed with UV inks is cured instantly. However, UV LED curing offers the added benefits of reduced heat and energy consumption.
Maxwell says the instant dry time of UV inks means that bleeding and migration issues often associated with other inks are not prevalent. “This also offers the added advantage of printing to uncoated paper goods, such as corrugated board, without concerns of the ink wicking into the material.”
“The marriage of UV or LED lamps to ink combination is imperative to the UV printing process,” notes Barry.
Hutcheson points out that UV LED curing allows for a broader scope of print applications and enables printing on heat-sensitive substrates such as corrugated board and cardboard. “As less heat dissipates from an LED lamp, it is easier to keep the media flat under the shuttle, eliminating disruptions. The investment in LED means fewer reworks and less media and ink waste in the long term.”
UV LED curing also eliminates the need for solvent evaporation or special coatings, adding there are no volatile organic compound emissions, shares Hutcheson.
According to Kim, UV ink curing is more sophisticated than other processes. “UV light wavelength and power can determine cured portion of droplet, curing speed, and bonding strength.
“Curing on porous media like those used in liners can be very tricky,” cautions Donigain. “It is important that ink volume and suction is controlled as to not allow the inks to penetrate too deeply. If the inks penetrate the liner too deeply they may not cure fully. Using the right amount of ink, suction, and lamp intensity allows manufacturers to ensure that the ink is fully cured.”
Jackman notes that mercury UV lamps are utilized in all applications where UV inks are used, but recently there is a strong trend towards LED cure due to all the operational benefits provided. “For most applications, LED lamps work well when the correct ink chemistry is developed, but the availability of electron beams at the right price and dimensions could mean that it will start to be adopted more readily in labels and narrow web, wherever low migration is required.”
Specific to Packaging
Before a package is ready for the mainstream, it must meet several requirements. This includes shelf appeal and life, enhanced communication, recyclability and sustainability, and weight considerations. “All of this while also considering the complex regulatory landscape as the industry strives to make food packaging safer,” shares Jackman.
Several feature sets are attractive for PSPs looking to produce packaging applications.
Donigain says the primary advancement that sets UV ink up for packaging is media handling capabilities. “Corrugated boards are porous and usually warped. These two factors make it difficult to create a flat print surface with corrugated boards. With digital print technology, boards that aren’t flat can create reduced print quality, damage the printheads, or create jams.”
Recycling is another aspect to consider. Raimar Kuhnen-Burger, regional marketing manager – industrial print, EFI, suggests it is important to keep corrugated applications a highly environmentally sustainable packaging choice. “It is important that ultra-high-speed digital inkjet production technologies do not negatively impact the corrugated recycling supply chain and keep full repulpability.”
The introduction of UV LED curable inks opens up a wider range of available materials for packaging due to the lower heat produced by the bulbs. “Additionally, some ink manufacturers are developing multiple inks that support more specific applications, for example, different varieties from rigid to flexible, each one designed to meet a unique demand,” explains Maxwell.
Pre-Treatment or Coating
While UV ink adheres to many substrates without the need for special coatings or primers, these solutions do play a role in the compatibility of UV-cured ink on select media options.
Kuhnen-Burger says there are only a few board types developed especially for digital print released by the paper industry. Because of that corrugated packaging performs best with a primer. “Having a primer gives customers control over dot gain and ink absorption on different types of corrugated top sheets. It keeps the output consistent even if there are slight surface deviations from one production lot to another.”
Materials may require a pre-treatment such as a primer. “Some plastics for example may have a surface tension not suitable for ink adhesion and primer or pre-processing workflow may help overcome it,” admits Maxwell.
Hutcheson adds that depending on the material being printed and the ink’s ability to adhere to that surface, certain packaging applications may require a pre-treatment. She says for example, some packaging materials feature an extra slippery surface or surface that doesn’t provide the ability for the ink to grab. Pre-treatments help with adhesion.
“Coatings also provide different finishes to enhance the package. For visual appeal, there are gloss, matte, semi-matte, and luster coatings, plus others—and for tactile appeal, there are soft-touch coatings. Great examples can be found in cosmetic and luxury perfume packaging,” offers Hutcheson.
“Whether or not pre-treatment is required for the application, UV inks are very receptive to pre- and post-coatings. This makes UV inks ideal for most packaging applications,” shares Barry.
“There are some grades of ink that vendors claim do not need primers. However, it is safer to use primers for certain substrates,” suggests Kim.
Donigain says for boards with brown kraft liners, it may be necessary to use a white ink in print areas in order to achieve more realistic color and higher densities. “However, white ink is generally not required when printing onto corrugated board with white liners.”
Food Safety
One major consideration in packaging is its use with food and beverage goods. Packaging that makes direct or indirect contact with food is a complicating factor for production.
Barry points out that different migration level properties and curing technologies are being tested to make UV ink more viable for food safe packaging.
Many UV inks are already rated for food safety, according to Maxwell. “As demand grows in this area, more manufacturers will develop and certify their inks to support this.”
Hutcheson says Agfa is committed to the research, manufacturing, and testing of its UV ink solutions. “Our ink portfolio includes low-migration UV ink for food and pharmaceutical packaging applications,” she says. Low-migration ink does not move from the package to the food product.
Jackman points out that one of the main priorities for brand owners, converters, and customers is compliance and the issue of migration. Once mainly concerned with conventional printing, low migration and compliance are also important factors in digital printing and if not handled correctly, could have potentially severe consequences, such as damage to a brand’s reputation and risks to consumer health.
He says during the packaging design stage, particular attention is spent on ensuring the correct packaging materials are used to protect the various food products. “The selection of inks and coatings are equally important. To ensure Sun Chemical inks meet the necessary requirements and legislations, there are several factors that need to be considered, including an understanding of the legislation that regulates package printing, a knowledge of migration and the prescribed limits, and a responsibility for ensuring that packaging is correct for its end use utilizing correct testing protocols through all key players on the supply chain,” continues Jackman.
Kim believes that due to food safety issues, major companies promote water-based latex or toners, but UV is still the most promising technology to print on both flexible and rigid uncoated substrates. “There are meaningful activities to develop and propose a certain grade of inks to get approval for use on food packages.”
Conversely, Donigain is not aware of any UV ink food safe packaging efforts. “As far as I am aware, the very nature of UV inks makes them unsuitable for direct contact with food. Water-based inks dominate the application.”
The Future
While UV-based, wide format printers have experienced growth and success with many applications, packaging is an area worth investigating. The latest advancements are working towards this.
“In our experience, UV inks offer a range of capabilities. However, UV-curable inks by nature have slightly larger drops compared to other inks available. For this reason, we believe that as demand grows, UV-curable inks will be developed with this in mind, bringing these inks more in line with the demands of packaging,” foresees Maxwell.
“Ink attributes are always evolving. About ten years ago, ink was brittle. Today’s inks are flexible, which broadens digital applications like thermoforming or bending a surface into a 90 degree angle,” says Hutcheson. She adds that ink will continue to evolve to satisfy future application needs.
Currently there are many choices of inks to use ranging from more flexible to more resistant to chalking or more vibrant. Donigain says finding the right combination of flexibility, resistance to chalking, and vibrancy is key to the future success of ink.
Consider UV
Several areas of packaging benefit from UV and UV LED printing equipment. While there are some challenges to consider this ink’s many benefits make it an attractive option for packaging applications.
Oct2018, Digital Output
