Hot Stuff

Something old, something new, something borrowed … When it comes to technology evolution, this old wedding custom has some meaning. Older technologies don’t just disappear as soon as something new shows up. Many times the old and the new coexist and complement each other for sometime. Even if and when the old guy gets put out to pasture, the new technology is usually better off because of something it “borrowed” from the wise old technology.

Well, thermal printing (including direct and thermal transfer) is one of those older technology arenas that is feeling the “heat” from the new kids on the block, like inkjet and digital printing, or even RFID, which, some say, could supplant thermal printing’s bread-and-butter—bar codes.

Despite this formidable competition, thermal printing is far from being put out to pasture. It is not only going strong in its traditional strongholds, but is taking advantage of new regulations and requirements to expand its place in on-demand, variable data printing.

Thermal transfer is currently used in the pharmaceutical industry for lot, date, and bar coding, says Rick Harris, product manager for FLEXcon. However, outside of pharmaceuticals, Rich Garber, business development manager at FLEXcon, says, “there are relatively few on-package applications using thermal printing, as inkjet is the predominate technology for date codes and lot codes.”

Secondary packaging is an area where thermal transfer printing has a strong presence. “Thermal transfer is utilized extensively at the carton and pallet level, as well as for warehouse, distribution, and some point-of-purchase applications,” notes Garber.

Keigo Hayakawa, president, DNP IMS America Corporation, concurs, and highlights other areas of expanding use. “The vast majority of thermal-transfer ribbon usage remains in secondary packaging, such as carton labeling… Also, one of the fastest growing market segments is flexible packaging marking, or commonly called thermal-transfer overprinting (TTO). Historically, the traditional method of marking has been the use of hot-stamp foil imprints in the food and pharmaceutical industries. Due to recent requirements for identifying lot traceability and quality assurance controls, thermal transfer printing is replacing the historic print method of hot stamping foil, taking advantage of printing variable information right on time. This replacement will continue, which will drive the growth of thermal transfer printing.”

Requirements to improve the accuracy and reliability of dispensing pharmaceuticals will help fuel opportunities for direct thermal printing, says Mike Cove, marketing manager, identification products, for Appleton. “In the healthcare industry, new applications are developing in which direct thermal provides the solution for mini bar codes on unit dose drugs to comply with FDA directives and to help automate the prescription filling in a hospital environment, or for prescription documents, eliminating errors due to doctors’ handwriting.”

Direct vs. thermal transfer

Thermal printing is not only competing against other technologies, but direct thermal printing and thermal transfer printing are vying for use in the same application areas. Each has its advantages and disadvantages.

In thermal transfer printing, the ink is carried on the ribbon and heated and transferred to the substrate. “The advantages of thermal transfer printing result in dense, high-resolution images—color or black-and-white—and can be used on a wide variety of substrates,” says Hayakawa. This ability to print a durable image on “a virtually unlimited universe of substrates” is what makes thermal transfer printing one of the primary methods for printing bar codes.

Additionally, Garber notes that thermal transfer is more durable than direct thermal and does not need special media. “This method is used when durability and UV resistance is most important.”

The disadvantage of thermal transfer is that it requires two consumables, the ribbon and the substrate. “The cost of the ribbon, the need for two consumables, and the required ‘mating’ of correct ribbon with correct media choice could be considered disadvantages,” says Garber.

With direct thermal printing, the ink is carried in the substrate, so the fact that it doesn’t require a second media (the ribbon) is a clear advantage. Further, says Hayakawa, “Images produced by direct thermal printing are clear and defined; and direct thermal printers are cheap, simple to operate, and easy to maintain. Direct thermal printing for bar code labeling is certainly an improvement over inkjet and laser technology, especially when it comes to speed and resolution.”

Cove points out that direct thermal has some inherent advantages. “It is undeniably simple, with the imaging almost completely solid state.” In addition, since the coated paper is the only media involved, print consistency is improved because the first and last images are of equal quality.

However, as compared to thermal transfer printing, direct thermal uses specially coated papers, which limits the substrate choice. In addition, the coated paper is more sensitive to light, heat, and abrasion, says Hayakawa.

Competing technologies

Other digital printing techniques are continuing to improve in both quality and cost, acknowledges Cove. “Inkjet technology in particular, spurred by the need for low-cost photographic printing, has made some step improvements that will challenge conventional prime labels. The benefits are similar to direct thermal in terms of point-of-use simplicity.”

However, he notes some drawbacks when compared to high-efficiency direct thermal label printing. “Consistency of the printed image depends on high compatibility between the ink and the media to prevent a ‘washed out’ image, whereas the uniformity of the image with direct thermal is inherent in the colorless ink layer of the paper.”

When it comes to RFID, it’s too early to say what the full impact will be relative to the use of bar codes. “Ultimately, most bar code applications using thermal transfer could be a candidate for replacement by RFID technology,” says Garber. “But, just as bar code technology rolled out over many (30+) years, RFID will not replace thermal transfer for quite some time. Also, even with RFID, thermal transfer will continue to be used for those applications where variable information must be human-readable.”

Hayakawa does not believe RFID will ultimately replace bar codes, because of cost and bar code infrastructure issues. If RFID could get its costs down to the current bar code labeling costs, he believes it could pose a threat to the thermal transfer industry. However, he says, “The reality is—there is an unlikelihood that RFID would reach the cost level of bar code labeling.”

“We believe these two technologies are entirely different tools and will co-exist or stand independent based on the requirements of the application,” he adds.

Cove concurs, saying, “RFID and variable imaging bar codes will work in parallel for many years to come, each finding its own niche and benefits for the end user.” pP