TECHWATCH tm: Offset + Digital = Security Runs

Document Security Systems (DSS), an anti-counterfeiting firm in Rochester, NY, recently won a patent dispute in the Hague, Netherlands. The judgment will allow it to pursue an infringement action against currency printers for all the paper Euros currently in circulation. It turns out that companies printing the Euro may have violated a security process patent of DSS.

Ironically, this may be one way to get the value of the Euro down a little by transferring some revenue to a U.S.-based inventor. This case also points out the value in the use of multiple applications of printing processes to provide additional layers of protection to a wide range of products. Kodak's Traceless technology—which uses microscopic quantities of a tracing chemical marker to distinguish real print jobs from fake ones—is another good example of the emergence of techniques that employ a printed process to add product security.

How can the average day-in/day-out job run, for typical customers at a standard-issue printing production facility, use technologies at hand to improve product security? One answer may lie in added techniques incorporated into coatings being applied to printed products. Epic Products, the Arlington, TX equipment maker long famed for its Dahlgren dampeners, is presenting one reasonable approach with its new CT-660 coater product.

The system, used offline or inline in either digital or offset applications, allows for mixing sparkling solids within the applied coating—in combination with a coater incorporating a flexographic cylinder delivering either spot coatings or a flood coating. The accompanying illustration (above left) shows the interesting results attainable.

This can make for a reasonably effective, attractive and economically viable anti-counterfeiting measure for product packaging, or for imparting security control to high-value products such as lottery tickets. Often, such products use eight or more printing processes to make knock-offs nearly impossible. Today, with the emergence of wide-format inkjet and digital printing along with traditional offset, the typical printing plant may have the requisite diverse processes to offer something new and of value to customers by applying special coatings at the end of a multi-platform process.

Taking a closer look at the Epic technology, one finds strong doses of both printing industry technical knowledge and craftsmanship within its coater. Epic Products was one of the first companies to coat on an offset press.

With more than 30 years of experience, it has designed coating systems for all types of traditional, heavy web and sheetfed graphic coating systems. There are two basic types of metering systems used to coat: roller metering and anilox metering. Roller metering uses a combination of roller nips and speed differentials to determine how much coating is metered from one source, such as a pan to the substrate. Even at its best, roller metering is highly subject to operator settings, roller hardness, precision of the machinery that will apply it, and can produce a coating film subject to variation during operation.

In addition, matte, satin and dull coatings tend to show variation, streaking and roller chatter. The final product with these coatings is usually marginal in quality. For all these reasons, virtually all high-end sheetfed offset presses with inline coaters have made the move to anilox metering.

Anilox metering is the same system used to meter inks in flexo printing. Typically, a laser is employed to engrave tiny cells of a precise size diameter, depth and volume into the surface of an extremely durable roller. An enclosed chamber doctor blade delivers coating or ink to the anilox roller, and a precision blade wipes away the excess to deliver a consistent film of coating.

The result is a precise, repeatable and consistent film that does not require a lot of input from and is not highly dependant on the settings made by the operator. Because pressure nips and differential speeds are not used, coatings with dulling agents and metallic pigments are applied evenly with no streaking or chatter.

The flexographic plate system for applying coatings to substrates on high-end offset presses is based on either printing blankets or flexo plates. All coating applied to the plate is transferred to the substrate, and none of the coating reaches the back or impression cylinder. This system also allows for spot, security and knock-out coating techniques (as discussed earlier), and it's accepted as state of the art in offset and now digital print coating.

Roller systems applying overall flood coatings will, when the press is on impression, transfer coating to the impression cylinder even if no sheet is present. So these systems require wipers to remove and recalculate the coating back to a pump to return it to the pan to be reused. As this technique is less than perfect, many of these systems prohibit two-sided coating and, as with roller settings in the metering area, require considerable input and maintenance from the operator.

Epic Products uses both an anilox metering system and flexo plate application of coating to provide a consistent, easy-to-use process for both the offset and digital printer. Epic also incorporates a gripper system to assist with the ability to coat a wider range of substrates and weights. Sophisticated coating techniques are easily achievable, and maintaining consistent output is easy. Maybe this offers a future in your plant for security coatings.

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