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Water-washable ink steps up to the plate

May 1, 2001 12:00 AM


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RUB RESISTANCE WAS BETTER IN FIVE MINUTES THAN A CONVENTIONAL WATERLESS INK AFTER 24 HOURS.

At Drupa 2000, Sun Chemical Ink (GPI) (Northlake, IL) announced the release of DriLith W2 for sheetfed presses operating waterless, and Instant Dry W2 for Heidelberg's Quickmaster DI presses. The new waterless inks have been modified to allow the use of a press wash solution consisting of water and a mild surfactant similar to soap.

POSITIVE ENVIRONMENTAL IMPACT

Greensboro, NC-based L&E Packaging, which operates six sheetfed presses 100 percent waterless, used DriLith W2 for more than two years, first as a beta site and now in live production. Sources at L&E estimate their total volatile organic compound (VOC) reduction is conservatively upwards of 95 percent.

The environmental impact of using water-washable ink, which could easily result in expansion opportunities that were previously limited due to VOC restrictions, means waste water from press wash-ups is now drain-safe. The hassle and expense of hazardous material disposal is gone.

The amount of VOCs in Sun's DriLith W2 constitute less than one percent, according to the EPA Method 24 testing procedure. By comparison, the VOC content of Sun's regular waterless ink ranges from 15 percent to 24 percent by weight.

Even zero-VOC inks, available in Europe, still require conventional solvents for roller and blanket washing.

WHAT ABOUT THE SURFACTANT?

A surfactant can briefly be defined as a material that can greatly reduce the surface tension of water when used in very low concentrations. Soap, by this definition, is a surfactant. Surfactants allow the detergent solution to wet the ink-soiled rollers and blankets so that the ink can be suspended in water and thus easily flushed from the surfaces being cleaned. Sun claims there are no hazardous air pollutants (HAPs) in the specially formulated press wash and it can, therefore, be safely disposed of.

While there are small amounts of VOCs in the surfactant used currently, Sun's goal is to eliminate the need for a surfactant altogether and enable wash-ups with 100 percent water.

Following successful trials of its water-washable ink at L&E Packaging, Bayshore Press (Monterey, CA) and Amos Communications (Beloit, OH), Sun Chemical is proceeding with master batches of DriLith W2 for distribution to those three waterless printers.

According to L&E production manager Danny Isley, L&E officially signed off on the ink following the most recent test, which measured dot gain, trap, transferability, washability, the ability to receive UV coating, a fast rub test and fade test. A side-by-side comparison of the same test form printed with Sun's regular waterless inks, which L&E has been using for nine years, showed no discernible difference.

Isley is pleased with the results. “We weren't looking for something that we would have to take to our customers and say, ‘This works, if you give up this.’” L&E prints hang tags and pocket flashers for leading clothing manufacturers, and color accuracy and consistency are critically important.

PROCESS ADVANTAGES

Mark Hoover, president of Bayshore Press, is always on the lookout for environmentally kind processes. Stemming not only from a sympathetic regard for the environment, Hoover's quest also reflects the success Bayshore has had marketing the uniqueness of waterless printing and the ecological benefits of the process. The elimination of pressroom VOCs will be fully appreciated by Bayshore's customers.

The exec did not go through a lengthy testing procedure prior to placing his order for DriLith W2. Bayshore ran four live jobs with the new ink, all repeats of previously printed products. In Hoover's opinion, all four looked as good or better than the original printing, and that convinced him to make the switch to the water-washable ink.

Hoover was surprised at the effectiveness of W2's wash-up solution. It took a little longer to clean the rollers, but the blankets cleaned up at least as quickly as with a solvent-based solution. Bayshore's press operators like it for numerous reasons, including the fact that it easily washes out of their clothes and off their hands.

Amos Communications ran a seven-color test form supplied by the press manufacturer for its initial ink trial. Side-by-side comparisons on coated paper were encouraging, despite the fact that three PMS colors had to be hand mixed from the process set supplied by Sun.

The new ink seems to have a higher tolerance for heat, performing at its best in this particular test when the plate temperature reached 90°F.

Drying time was impressive. Rub resistance of DriLith W2 was better in five minutes than a conventional waterless ink after 24 hours.

It should also be noted that the relative lack of mineral oils or petroleum distillates seems to ensure good press stability. The press can remain idle for extended periods of time without ink drying on the rollers. The ink can remain in the ink duct without skinning overnight and possibly for as long as 48 hours.

While early formulations of W2 suffered from inferior gloss, the tests run by all of these printers showed a level of gloss at least as good as standard waterless inks.

A LESS THAN STELLAR PERFORMANCE

Fontana Lithograph, a high-end commercial waterless printer based in Washington, did not enjoy the same level of success in its trial of DriLith W2. Increased dot gain and ineffective wash solution sent the ink back to the lab for further development.

Fontana Lithograph has always been technology-driven, and tends to look at the numbers behind a print job, not just the appearance. The methodology of its test was as follows: A standard test form was run in the morning on a 100-lb., No. 2 gloss-coated sheet, with and without aqueous coating supplied by Sun Chemical. The printer ran about 200 sheets, stopped, took measurements, made adjustments, ran another 200 sheets, and repeated the process. Following the DriLith W2 test, the press was cleaned and the test form was run in the same way, using Fontana's regular waterless inks from another vendor.

The measured densities and dot gain showed that the DriLith W2 was printing fuller than the other vendor's ink. Fontana's press operators had to pull back on densities to compensate for the increased dot gain, which would lead to diminished control over the process, and not run the full ink film thickness that is so integral to waterless quality.

The wash-up solution Sun Chemical provided for the trial had to be manually applied, and still left a thin film of ink on the rollers.

According to Fontana principal Brendan Connors, the company's primary goal is to eliminate pressroom VOCs without negatively impacting its products. The environmental nature of waterless printing is a big selling point in Fontana Lithograph's market. But Connors doesn't want to take a step backward in terms of efficiency, either. He believes that an acceptable press wash will be one that adequately cleans the rollers and blankets, and is in sync with Fontana's automated press operations.

To further complicate the situation, Fontana currently runs only its four-color process waterless. Spot colors are conventional inks using conventional dampening, and don't always utilize the same units on a press.

BACK TO THE LAB

On the positive side, Connors acknowledged that the W2 ink is stable on press. Normally, with the run-stop-wait-run scenario of the testing procedure, ink has a tendency to dry the rollers. But the new ink neither dried nor piled on the rollers.

Connors will continue to work with Sun as it adjusts the W2 ink and press wash solution to meet Fontana's standards.

Dick Drong, Sun Chemical's marketing manager for sheetfed inks, says that the changes required for a successful launch at Fontana Lithograph are straightforward, and will probably only require a nominal adjustment to the viscosity of the ink. He also believes a little more work in the R&D laboratory will make the wash-up solution more effective. That will undoubtedly require either a different surfactant, or a greater amount of surfactant in the solution. Since Sun's stated goal is to enable DriLith W2 to be effectively cleaned up with water alone, the adjustment process is likely to be ongoing.

It should be noted that each of the four printers mentioned here operate different press equipment, and with the exception of L&E, this was the first time the ink was run on those presses.

All things considered, this is a huge leap for environmentally conscious printers. For those operating 100 percent computer-to-waterless plate, the goal is within reach. The next small step to a totally VOC-free pressroom is 100 percent water-washable zero-VOC ink.

For additional information on waterless printing and water-washable inks, contact the Waterless Printing Assn. at (800) 850-0660 or visit its website, www.waterless.org.