By Olivia Cahoon
Electrophotographic (EP) and liquid EP (LEP) production printers utilize mature digital printing technologies that use dry and liquid toner to print onto a range of papers and substrates. Dry toners consist of pigments that embed inside polymer beads that melt to the paper surface while liquid toners use pigments in polymer beads that are dispersed in an oil that evaporates during fusing.
Compared to inkjet, EP devices are compatible with a larger variety of substrates. Smaller particles allow toner to be densely packed with color while uniform particle shapes contribute to consistency. As a result, a richer spectrum of color enables a broader variety of applications.
LEP devices utilize an alternative to liquid carriers to deliver speed and quality. HP Indigo’s LEP technology uses HP ElectroInk, which accurately places tiny dot particles on substrates for sharp, high resolution, and well-defined images.
A variety of media vendors offer substrates specifically designed for optimal output from toner-based devices.
Above: The Curious Collection with i-Tone is distributed by Mohawk and manufactured by Arjowiggins Graphic. i-Tone is a surface treatment that improves toner adhesion on substrates for HP Indigo presses.
While many are quick to point out the importance of quality and price for substrates compatible with EP/LEP devices, product reliability allows printers to have maximum uptime and consistency.
Craig Surette, director of business development, dry toner market, GPA, says product reliability applies to the overall benefit of specialty substrates like labels, synthetic papers, and unique papers. “Printer peace of mind, being able to run the job with confidence, and not fighting the press—these are the key media drivers we hear from our customers,” he offers.
Michelle T. Garrett, national account executive, digital and specialty papers, Verso Corporation, agrees and says print providers need substrates that deliver reliable performance throughout imaging and finishing since turnaround times are generally short.
One of the best ways to ensure a product’s reliability is to determine if the substrate manufacturer or distributor partners with the press manufacturer. “Digital substrates are designed and optimized to perform on different print engine, in partnership with the press manufacturer, so it’s important to select the right media for your print engine,” says Garrett.
Still, print quality and price are primary features that digital print providers look for in substrate selection. Mark Anderson, executive director of sales and operations, South Coast Advantage, says quality varies based upon the equipment. Substrates must be able to support transfer and toner fixation without added problems. He suggests low moisture is the difference between papers that perform and ones that don’t for many toner-based machines.
“HP Indigo requires specific surface chemistry, which allows the ink to adhere to the stock. It’s important the user tests the stock prior to placing an order to assure the proper performance is achieved,” offers Anderson.
Due to faster turnaround expectations, digital presses compete with offset. As a result, paper costs are important. While digital substrate costs should be reasonable, they are expected to be more than offset papers. With value-added applications like variable data, cost becomes less important.
EP/ LEP Specific Substrate Features
Printing on EP/LEP devices requires optimized media for each individual device. EP devices use high temperatures and pressure to fuse toner particles to the paper. This presents challenges for heat-sensitive substrates.
High temperatures mean that most synthetic materials are difficult to use with EP devices. Dan Lawellin, director, business development, Kernow Coatings, explains, “the charge profile required to form an image tends to build up a large amount of static in synthetic sheets. These synthetics tend to hold that charge, much like a balloon that you rub on the carpet and then stick to the wall using static.” Static build up can cause jams and print artifacts to appear.
To avoid static complications, Lawellin says media manufacturers incorporate features to optimize the synthetic substrate’s performance in the press. “We’ve stabilized sheets to handle the head of the fusing systems and we’ve dialed in the charge profile for synthetics, so they can take the imaging charge but quickly disperse it,” he offers.
While EP doesn’t require primers, Kirit Naik, director, research and development, America, UPM Raflatac, suggests it does need testing compatibility. For example, if high heat is used then clear, thin substrates might present printability challenges. As a replacement, a similar thickness white film can be used because it has inorganic, heat-resistant fillers. “Customers would need to evaluate hot melt adhesive-based label stocks for a dry toner system,” he explains.
Melissa Campbell, marketing manager, Masterpiece Graphix, points out that traditionally, print providers felt limited to just polyester substrates because of high temperatures required for EP. But with substrate advancements, print providers can choose more options for dry toner like synthetic paper and plastic.
In LEP systems, most of the oils are evaporated during the heat process so temperature is less of a concern. These systems present a different set of challenges including creating a film across the material’s surface when the image sets.
For synthetic papers on LEP devices, Lawellin explains that print providers bond film to film, which requires the proper surface chemistry. “We create an optimized surface that allows the LEP technology to form a strong bond with the surface, locking the color, image, and print,” he explains.
John B. Cooper, technical director, Arjowiggins Graphic, says EP/LEP substrates are separately optimized for moisture and smoothness, which is required for optimal toner transfer and toner adhesion.
Because there are fewer LEP devices than EP, some print providers may feel limited to specific materials created distinctly for LEP. However, Campbell says there are substrates engineered to perform on LEP devices as well as EP presses and many offset and flexographic machines. “These materials are tested and designed for high printing temperatures of toner presses,” she explains.
Managing Substrate Challenges
Smaller inventories and broad product portfolios present challenges for print providers when selecting substrates. Access to large warehouses for inventory and equipment is a luxury that many print providers cannot afford, therefore stocking the best compatible substrate options is critical.
“Most print providers expect suppliers to quickly turn around product requests and maintain a wide breadth of products so they don’t have to. Size notwithstanding, availability is always a critical driver,” says Scott Schweder, director of business development, Domtar.
Another challenge for EP/LEP substrates is determining which products are compatible for EP/LEP presses. Some products are cross platform and work on different types of devices while others are specifically intended for certain technologies. Joe Schember, product manager, digital specialty and paper, Mohawk, says equipment compatibility charts exist from media vendors to help printers match digital presses to available compatible media. “Because we have done extensive testing with the equipment manufacturers, these charts go beyond just stating compatibility to include specific settings by press model, hints and tips, and any other FAQs available regarding the product,” offers Schember.
Substrate specifications, specifically thickness, present limitations on some printer models. According to Jim Cirigliano, marketing manager, Magnum Magnetics, many printer models have thickness limitations and as a result, press manufacturers won’t certify media that exceeds a certain weight or thickness.
As previously noted, some presses run fairly hot—creating problems for printing substrates affected by high heat. Cirigliano says certain products are designed with these types of presses in mind. “These options include thinner overall material that falls within the printers’ limits and with constructions that perform better under heat exposure,” he offers.
Heat is particularly challenging in the plastics market. Rebecca Fuhrman, market development manager, Tekra, says high fusing temperatures with toner-based presses can limit the amount of usable film substrates because some film types can stretch or warp under high heat. This causes print registration loss or the ability to be easily processed during post-print operations. “It’s important to select a material that can handle the heat needed to fuse the toner while still meeting the application needs,” she offers.
For printing on boards, John Sarik, technical marketing manager, Metsä Board Americas, says that finding the proper board sizes can be challenging. “If you pick the wrong board, print it with a solid black, overprint it with a coating, and put it on a folder gluer only to get cracking on the 180-degree fold, then you have to repeat the process,” he explains.
Quality, availability, and cost are primary considerations for media providers serving an EP/LEP market. By keeping customer focus in mind, Nate Gill, product manager, Mactac, says media offerings will meet and exceed customer needs.
“Moreover, the technology within the EP/LEP market is quickly advancing. Mactac takes an active role in monitoring these developments to ensure our media is available and optimized for the new equipment our customers are acquiring,” he offers.
Not all print providers produce the same applications and as a result, diverse substrate demands need to be met. Jason Depner, labels and print segment manager, TESLIN substrate products, PPG Industries, believes offering substrates with a range of application-specific grades compatible with numerous digital print processes is one of the best methods for serving each client. Different needs include certified grades for direct food contact or grades that decompose in landfill environments.
Anders Fransson, group technical and environmental coordinator, Arctic Paper, suggests the main consideration for media manufacturers and distributors is maintaining a plentiful substrate stock. He says the average delivery size is very small, roughly under 100 kg. Substrate suppliers should have several versions of substrate options with different grades, grammages, formats, and grain direction.
“To have a complete and attractive offer, the cost for keeping stock articles and handling deliveries becomes huge,” he explains. As a result, manufacturers and distributors are conscious about substrate offerings including options in different sizes and features.
In addition, media recommendations and certifications give print providers confidence that media will successfully perform. According to Brian Ayers, market development specialist, FLEXcon, certifications or recommendations for substrate options for EP/LEP presses are driven either by the market or end users. Substrate manufacturers and distributors generally test substrates with several print technologies so print providers know which options are compatible with their presses.
Manufacturers and distributors like FLEXcon also test products to ensure compliance with various agency standards. “Toner-based printers have always been used in the petrochemical market; however, due to the implementation of the Globally Harmonized System of Classification and Labeling of Chemicals, there is now a requirement for variable imaging in color where in the past it was only required in black,” explains Ayers.
Available Toner Substrates
A variety of substrates are compatible with EP/LEP production devices. Here we highlight a selection of these products.
Arctic Paper’s Munken Polar ID is an uncoated paper certified for HP Indigo printing with a high-quality print target. It includes a special surface treatment optimized for toner devices. “We also have other shade versions from cream to natural white and crisp white and high white,” says Fransson.
Arjowiggins Graphic offers Cyclus and Cocoon compatible with all major dry toner manufacturers like Canon, Konica Minolta, Ricoh, Xerox, as well as HP Indigo. Cooper says both products have excellent OEM-guaranteed toner adhesion and sheet size accuracy.
Domtar’s Cougar Digital Color Copy is photo certified for HP Indigo 5500 series and higher presses. It’s compatible with liquid or dry toner devices and is FSC certified. It features vibrant color reproduction and superior ink adhesion. Cougar is intended for brochures, business cards, direct mail, postcards, uncoated photos, and variable data.
FLEXcon DRUMcal and FLEXcon LAZRfilm products were released in 2016. A gloss topcoat is available for both substrates. Topcoat technology is used for optimum ink adhesion and liners allow consistent feed ability without curling. FLEXcon partners with HP, Konica Minolta, Lexmark, Microplex, OKI Data, Ricoh, Xeikon, and Xerox. Ayers points out that prices vary depending on adhesive and finishing requirements.
Released in February 2017, GPA offers Ultra Digital Synthetic Paper. The collection has a chemically engineered topcoat for dry toner presses and is compatible with all production-class dry toner presses including Canon, Kodak, Konica Minolta, Ricoh, and Xerox. According to Surette, Ultra Digital is guaranteed for printer compatibility, toner adhesion, and print quality. It is a soft, yet durable, synthetic print media that can be flexed and abraded. It’s available in a variety of thicknesses and sizes and doesn’t require lamination or top coats for image permanence.
Kernow Coatings offers KernowPrint for dry toner and KernowPrint for HP Indigo devices. For dry toner, the substrate is optimized with a proprietary coating designed for toner and laser printing while resisting alcohol and static. It is compatible with devices like Canon, Konica Minolta, MGI, Ricoh, and Xerox. KernowPrint for HP Indigo uses Cobalt Coating Technology to provide an optimal surface for printing and static control. “We have created a heat-stabilized material that easily handles temperatures well beyond what fusing systems produce,” says Lawellin.
Mactac STARLINER and METRO Digital substrate brands are non-ooze adhesives that withstand heat and pressure while avoiding gum buildup. Gill says the brands are available in sizes for most EP/LEP presses. STARLINER sheet products are pressure sensitive and certified for HP Indigo Digital presses. METRO pressure-sensitive sheets are suitable for kiss cuts and are used for applications like point of purchase, package identity, address, routing, and shipping labels.
Magnum Magnetics offers DigiMag PLUS and DigiMax XTRA. Both solutions are offered as polyester and paper with DigiMag XTRA as premium paper. Cirigliano says Magnum Magnetics media for toner devices are typically provided unmagnetized for easy feeding and handling. Media can be magnetized post print using a patented magnetizer solution.
Masterpiece Graphix GlassMate is an ultra-low tack, washable, removable, and repositionable decal film for indoor and outdoor use. It’s primarily used on glass or other smooth, glossy surfaces. Campbell says the proprietary adhesive system allows decals to remain in place indefinitely on most interior applications and remove easily without leaving any adhesive residue.
Metsä Board’s board products have a coating chemistry that accommodates EP/LEP devices. The board allows ink to setup on surfaces for a sharp dot reproduction. This coating technology is compatible for offset and digital inks. “The board and liners we provide are readily available by our stocking program, and we have converters, if needed, to produce the sizes needed for the industry,” says Sarik.
Mohawk offers over 1,000 digital items including Chromolux for HP Indigo and the Curious Collection with i-Tone. Chromolux is available as high-gloss papers and boards. It features cast-coated, one-side, high-gloss surfaces in a range of calipers, colors, and metallic finishes. The Curious Collection is manufactured by Arjowiggins and distributed by Mohawk. It includes seven grades with different textures. Mohawk i-tone is a surface treatment developed for the HP Indigo presses that improves toner adhesion on substrates.
PPG TESLIN TS is a synthetic paper introduced in the early 1990s. It’s used for high-quality commercial print, labels, and packaging applications that require durability. The substrate has micropores that absorb ink and toner to protect against wear from handling and abrasion. It’s compatible with a range of digital press models without requiring special coating. According to Depner, TESLIN TS is exceptionally durable and resistant to water, chemicals, and tearing. “It has a unique, soft and supple feel that helps printed pieces stand out when handled,” he offers. TESLIN TS is available in a variety of thicknesses and sizes.
South Coast is an HP recommended coater/converter. The company offers varied substrates and sizes and optimizes paper to work on HP Indigo presses. According to Anderson, optimization is recommended on substrates running on industrial one-shot presses. “Our company’s digitally optimized products can achieve high-quality adhesion and extended blanket life,” he explains.
ToneKote from Tekra uses a proprietary toner-specific topcoat that enhances toner adhesion and converts to the customer’s specific needs. It targets high-quality printing and is compatible with Ricoh, Xeikon, and Xerox devices. “We coat our film to allow for the best toner adhesion and include properties to help minimize static buildup on the sheet in process,” says Fuhrman. She believes these features ensure print quality and withstand any post processing.
UPM Raflatac recently launched a printer recommendation tool that delivers a comprehensive database of paper and film materials for a variety of digital printers. According to Naik, the tool provides product information about UPM Raflatac’s digital label stock materials and ratings for how they perform on various printers from small desktop models to large digital printers.
Verso Corporation offers several papers for toner devices including Futura. Futura’s paper construction is fiber rich for performance through the bindery. It’s designed with a patented coated surface for runability and printability that meets Canon, HP, Kodak, Xerox, and other OEM standards. According to Garrett, it’s a preferred choice for high-end projects that require output that rivals conventional offset printing.
Media manufacturers address toner-based substrate challenges like compatibility, heat, and versatility with digital media lines that are optimized for EP/LEP devices. Before selecting a substrate, print providers should consider factors like stock availability, price, print quality, and reliability to ensure the best substrates for their presses and core applications are always stocked.
Jan 2018, DPS Magazine