Moving Beyond Black

Black thermal transfer ribbon's popularity suggests a steady industrial applications stronghold, although the color spectrum is widening.

by Susan Friedman

With a bar code or other variable data as a calling card, thermal transfer printed packaging commonly carries identification, shipping or tracking information.

Thermal transfer's sharp, crisp output has made it the on-demand printing method of choice for newer bar codes that can be read from a distance, and improved compliance labeling, states René Gallet, thermal products manager at Printronix, Irvine, CA.

A similar following in higher-end package printing remains to be seen. Thermal transfer speeds of six to eight inches per minute remain a disadvantage with larger prime label runs, notes Anne Myers, product/market manager at IIMAK, Amherst, NY. Myers says studies show thermal transfer to be cost-effective for runs of 10,000 prime labels or less, in which the biggest bottom-line benefits arise from eliminating traditional press set-up time.

Ribbon Carries the Story

Development and purchasing trends in thermal transfer ribbon, the "ink" element of this process, readily support a heavy industrial printing emphasis. "Not many suppliers have a very wide color offering," states Myers.

"Black ribbon is number one—no other ribbon color comes close [in terms of usage]," affirms Terry Smith, national sales and marketing manager for Japan Pulp & Paper, Tucker, GA. According to Smith, ribbon popularity is driving availability trends. "Black is readily available off-the-shelf," he says, "while colored ribbons are primarily stocked in 1 1Ú4˝, 2 1Ú4˝, 3 1Ú4˝ and 4 1Ú3˝ widths to accommodate the more popular label sizes. Others may have to be slit to order."

The high volume of black ribbon work also makes it cheaper to manufacture, from a coating operations standpoint, explains Dennis A. Jordan, international sales manager for Sony Chemicals Corp., Mt. Pleasant, PA. Suppliers typically work with shorter batches of colored ribbon during coating operations, and thus face higher changeover costs that are passed on to the end-user, he says.

Ribbons for spot color work can be matched to a custom or PMS color, says Printronix' Gallet, while process colors can be achieved through an additive color process, in which ribbons apply one color at a time to build the desired image, just as plate separations build images on-press.

For thermal transfer printers with one printhead, single ribbons can be purchased with multiple panels of color that are applied in succession as the ribbon moves through the printer, explains Sony's Jordan. On multiple printhead printers, an individual roll of color is used with each head. He says although multiple printhead hardware is more expensive, the accompanying ribbon is more cost-effective because the user buys only the colors he needs, versus paying for unneeded colors on a panel-style ribbon.

Metallic ribbons, particularly silver and gold, are also obtainable but more expensive than traditional colors, asserts IIMAK's Myers. On packets of coffee, metallic thermal transfer printing is being used in place of hot foil stamping for variable components of the package, such as the name of the coffee, the ingredients and the bar code.

Before purchasing ribbon, printers need to nail down project volume expectancies and hardware needs. Gallet maintains that while ribbon lengths of 300 to 600 meters are typical, length is limited only by printer capacity. A 350 meter ribbon can usually accommodate 6000 4˝ x 6˝ labels. Japan Pulp & Paper's Smith advises printers to plan purchases with ribbon shelf-life in mind. Wax ribbon will keep for a year, resin ribbon slightly longer, he notes.

Wax Leads Purchases

Cream-of-the-crop, premium ribbon quality isn't a necessity for the majority of buyers. Myers estimates 75 percent of thermal transfer ribbon sold is wax ribbon, the least expensive and a common choice for bar coding applications and general printing on coated or uncoated paper tags and labels.

She estimates 20 percent of ribbons sold are composite wax/resin, and the remaining five percent purchased are full resin ribbons, the highest-priced formulation. Full resins offer the greatest degree of smudge, scratch and chemical resistance, and are generally selected to ensure image quality on more expensive synthetic substrates such as polyester film.

Newer ribbon formulations aim to pare down the selection process while expanding substrate compatibility. According to Pete Gallette, vice president of marketing at Advent Thermal Transfer, Romeo, MI, the ribbon market is adopting a "best of" philosophy that is changing the lower-echelon perception of wax formulations. In lieu of offering multiple grades of wax ribbons, Gallette cites a movement toward a resin-enhanced wax formulation with the versatility to handle a broader range of label stocks for low- and high-end printing needs. "This ribbon can also be sold at a more competitive price because of the efficiencies inherent in selling fewer formulations," he comments.

Setting up Variations, Operations

Perhaps the trickiest aspect of selecting ribbons is the degree of variation within the same formulation category; wax ribbon can consist of softer paraffin or harder carnauba wax, for example. Smith points out that softer wax ribbons will smudge more easily, but won't require as much heat to transfer onto the substrate.

Gallet of Printronix relates that ribbon differences could create printer compatibility problems. He compares ribbons to brands of photographic film, all of which bring slightly varied formulations to the table, but will work in any camera that is adjusted correctly.

Appropriate printer settings can help manage ribbon variances, and maximize overall ribbon and hardware performance. Harder resins won't transfer at all if the heat setting is too low, because the resin won't be able to solidify on the substrate, confirms Jordan, while a too-high setting can actually melt the ribbon's polyester carrier. General setting guidelines from each supplier will help, he notes, but some fine tuning for each ribbon will likely be necessary.

Advent's Gallette emphasizes the higher the temperature needed to print, the faster the printhead will wear out. Ribbons designed to print at lower temperatures can allow more efficient printhead use, and limiting steep temperature fluctuations in favor of a lower constant temperature can actually increase the print speed of the job, he contends.

A Path to More Packaging?

Future developments may entice more package printers to give thermal transfer a try as a complementary process. Print resolution is approaching 600 dpi, says Jordan, and newer near-edge and true-edge thermal transfer technology provides faster print speeds with a straighter path for the ribbon, while printing a wider range of substrates and allowing greater pressure to be applied.

In the next five years, Gallet expects to see multiple printhead printers offering two-sided printing in one pass.

Advent's Gallette sees many applications incorporating a combination of traditional and on-demand technologies to maximize the strengths and cost advantages of each. A food label with 4-color graphics could first be printed flexo, and then variable ingredient information could added using thermal transfer, he suggests.

No Universal TT Label Guidelines

How does the thermal transfer marketplace look from the substrate side of the fence? Here, one materials supplier shares additional pros, cons and pointers.

Thermal transfer ribbon durability is improving, particularly in terms of chemical and environmental resistance, says Bob Major, marketing manager for emtech-Emulsion Technologies, a pressure-sensitive base material manufacturer that collaborates with thermal transfer ribbonmakers in ongoing ribbon testing. Major sees particular improvement in the chemical resistance of black resin ribbons often used to print bar codes for tracking products "from the assembly line to the junk yard."

Noting thermal transfer's strides in color ribbon quality, Major confirms that "the technology is suitable for process work, but prints more slowly than traditional processes." However, he notes, using a paneled ribbon or multi-headed thermal transfer printer may be less expensive for printing short label runs than setting up a flexo press. "Two hundred custom labels at one dollar each, a high label cost, are likely to be less expensive in total than the minimum set-up charges for traditional plates and run time."

Under Major's rules of thumb for thermal material compatibility, paper label applications are often partnered with lower cost wax ribbons because the durability expectations of the label are normally moderate in scope. In film label applications, the surface treatment of the film (topcoated, print treated, etc.) and the severity of environmental conditions determine whether a wax, composite or resin-based ribbon are needed.

"Unfortunately, there are still no universal guidelines for matching thermal transfer ribbon and label materials," Major remarks. "For best results, converters and end-users should work with reliable printer, ribbon and base material manufacturers who have done compatibility research and have the technical support to make effective ribbon and label material recommendations."