Cationic Inks

My room at the Orlando Homewood Suites reeked of stale cigarette smoke, but I had asked for it. My Delta flight to the SGIA tradeshow arrived late, and, consequently, I was late for an interview. Further, because I’d traveled in khakis and a T-shirt, my preferred attire, I needed to change into proper corporate clothing, a suit and tie. The Homewood Suites clerk, a sweetheart, said I was too early to check in. I said, “I’ll take any room you’ve got.” Five minutes later, I regretted the decision – the “smoking” room smelled worse than my teen’s sneakers.

On page 14 of AutoWeek magazine’s August edition, you’ll find a black-and-white photo of the ’32 Ford coupe that decorated the Beach Boys’ 1963 best-selling album, “Little Deuce Coupe.” At the time of the album photo, Clarence Catallo’s “Silver Sapphire” deuce, a chopped and sectioned ’32 Ford coupe, featured an oversized Oldsmobile engine, a belt-driven blower topped by three Stromberg 97 carburetors, and a tubular, dropped front axle, tipped with drum brakes. (The latter would be an antediluvian oddity in today’s disk-equipped hot rods.) It also has handleless, front-opening “suicide” doors.

(Kids, if this doesn’t make sense to you, think of Tokyo Drift. See the deuce like you would a tangerine-orange, ’90 Honda CRX SiR, with the B16A engine, Volk racing wheels and other tricks; now see the car’s photo laser printed on Green Day’s “Time of Your Life” CD inset.)

In AutoWeek, Curt Catallo, the Sapphire builder’s son, wrote, “My dad took the car through every incarnation,” meaning, he, as many rodders do, changed the car’s look and purpose regularly. Clarence, nicknamed “Chili,” sold the Sapphire after the album-cover shoot, because he realized the car had become an icon; it couldn’t be changed again. He immediately bought an AA Fuel dragster and began implementing upgrades.

This story illustrates that engineers – and serious car guys are engineers of a sort – believe no task is ever completed. Engineers not only design and build our cars, ships and airplanes, but also design and build digital printers, and, in character, they seldom leave these alone either. It’s the same for the chemists, those who make printers’ inks. This year’s SGIA tradeshow proved, again, that both groups, fixated, can’t stop themselves. The print-machine changes and updates were too many to list.

This trend, however, works to a signmaker’s advantage. More than 580 exhibitors displayed myriad new products and upgrades to the 20,782 attendees of SGIA ’07 – SGIA’s 59th annual convention and exposition. You can see a complete list at SGIA’s website, or visit signweb.com. Meanwhile, here’ a few of many worth mentioning:

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• HP (San Jose, CA) unveiled and demonstrated its HP Scitex XL2200 superwide-format Industrial Printer that features the new, HP Scitex X2 printhead technology.

• 3M’s Commercial Graphics Div.’s (St. Paul, MN) many offerings included its 3M™ Panagraphics™ wide-width, flexible substrate that’s designed for first- and second-surface imaging.

• Roland DGA Corporation (Irvine, CA) announced that its SOLJET PRO III XJ-640 64 in. inkjet printer was named DPI Product of the Year for the Output Device Poster Category; Roland’s VersaWorks 2.2 RIP software and SCM-GPPG glossy photobase paper also placed. (Go to signweb.com to see the list of winners; also, ST will list them next month.)

• The Océ Display Graphics Systems Inc. (Chicago) Arizona 250 GT won the 2007 DPI Product of the Year Award in the UV Flatbed category. (It won the DPI Vision award in 2006.)

• EFI (Foster City, CA) exhibited its new, VUTEk QS3200r, a high-quality, high-speed, roll-to-roll UV-cure printer. The QS3200r also won the grand-format Product of the Year award, along with its sister, the Vutek 3360 with BioVu inks.

• Leggett & Platt Digital Technologies (Sunrise, FL) won the DPI Vision Award for its Virtu® HD8 superwide printer.

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Cationic ink
Gerber Scientific Product’s (South Windsor, CT) new, Gerber Solara ion™ printer deserves some press. The $80,000 ion (Gerber’s marketers chose lowercase spelling for “ion”) is an innovative, UV-cure, flatbed/roll-to-roll printer that, the company says, applies benzene-free, GerberCAT™ cationic ink to media. The four-color machine accepts media up to 64 in. x 120 in. and 1 in. thick. It’s innovative because cationic inks offer certain advantages over commonly used, free-radical, UV-cure inks. UV-cure, cationic ink printers are sometimes called “cold-cure” printers, because the systems require a less powerful UV-cure lamp.

Cationic inks dry quickly (to the touch); adhere to myriad materials, including glass and fabric; are flexible (think vehicle wraps); require low-energy lamps; and, Gerber says, have an expanded color gamut.

Interestingly, in 2005, two digital-print machine builders offered and soon withdrew their proprietary, cationic-ink systems, but, clearly, various engineers and chemists have kept after it, because cationic inks offer more final-job versatility than free-radical inks.

Industry consultant Vince Cahill says at least three ink companies are developing cationic inks. I’ll have more from Vince in a minute.

Following SGIA and Gerber’s Solara ion introduction, the Flaar Digital-Imaging Resource Center’s (Bowling Green, OH) website said, “Kudos to Gerber for daring to be first with a full-scale cationic ink.” Flaar’s website added remarks on the previous cationic systems, then summarized with: “On the assumption

that Gerber is using a truly cold cure, their advertisement is obviously not improper, and they deserve recognition for their innovation.”

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How it works
The word “cationic” evolved from the scientific word “cation,” which describes a positively charged ion group – one or more charged atoms – that shift toward a negative electrode. In UV-cure printing, the cation process occurs during the ionized ink’s exposure to the ultraviolet lamps, and this action rouses the photo-initiators that set off the polymerization (drying) process.

Generally, cationic inks use epoxy resins and are odor free. And, unlike the free-radical, UV-cure inks, cationic-based inks don’t require the UV-lamp rays to pierce the ink’s entire depth; instead, the exposure triggers a cross-linking action that methodically, and totally, cures (dries) the ink. Because of this, cationic inks produce denser ink deposits; they also shrink less (think dot-size control) and adhere to media better than free-radical inks. Finally, cationic-matched, UV-curing lamps operate at lower temperatures than other UV-cure systems, and this expands the media-use list to include more heat-sensitive items.

Outside views
Because Durst (Brixen, South Tyrol, Italy) had experimented with cationic inks, I queried Dr. Richard Piock, Durst’s managing director, regarding his company’s experiences. He said Durst’s research established concerns with cationic inks, because they could release benzene, a carcinogenic gas. “Although it is produced in very small quantities, this runs up against Durst’s strict ‘green’ philosophy,” he said.

And, although he could see advantages of applying cationic ink, Dr. Piock didn’t like the costs, either, which were affected by a limited materials supply. Durst decided to focus on its more economical, free-radical inks, improving them where possible.

In April, 2001, Dr. Stefan J. Eder presented a paper on radiation-curing printing inks to the Ink Maker’s Forum in Nuremberg, Germany. He wrote, “The regular sulfonium salt photo-initiators for cationic systems can release small amounts of benzene at the time of exposure to radiation.” He also wrote about new, sulfonium-salt-free cationic systems. These, he said, release neither benzene nor diphenyl sulfone.

By email, I contacted Vince Cahill, president of VCE Solutions (Waynesboro, PA), a consulting and business-relations firm. Vince has high knowledge of digital-printing printheads and inks. He said the Solara ion is “a daring offering that could open new possibilities for UV-cure inkjets.” He said Gerber’s ion uses Konica Minolta 512 grayscale printheads and a relatively low-energy (and low-heat), full-width, germicidal UV lamp, to initiate the cationic ink polymerization.

He also said Konica-Minolta (probably through Toyo), Sericol, Sun Chemical and a few others are developing cationic UV-cure inks for inkjet printing, so expect to see more introductions.

“One can also use them on surfaces that encounter food, beverages and human or animal skin, because total curing is certain, once it’s initiated,” Vince said. This information could be useful when selling POP signage.

Peter Marchi, Gerber’s executive director of marketing, said you can order an ion today (I’m writing this in November) and receive it by April.