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The UV prescription

Jan 1, 1996 12:00 AM

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Combine flexo preparatory plates, narrow web presses and UV-curable inks for high-quality pharmaceutical printing

Government regulations and business opportunities do not seem to go hand in hand, but now and again one begets the other. Right now just such an occurrence exists in the pharmaceutical industry.

Two situations have combined to produce a potential bonanza for printers and their suppliers. The first is due to a considerable marketing backlog caused by the delay in determining a new health care initiative. Drug companies have been holding back on the promotional packaging side of their businesses, waiting to see which way the government would go with its proposed health plans.

Meanwhile, cost cutting has been the order of the day. Apparently, not much cost can be eliminated from the product or its manufacture, so packaging and printing have borne the brunt of economy measures. This soon may change.

Another bright marketing spot comes from the approval of nearly 50 ethical (prescription-only) drugs to be sold over the counter, albeit in a reduced strength form. Examples include Tavist D, Pepsid and, just recently, Tagamet. Competition for customers among these products already has spurred demand for more attractive packaging, which translates into more business for printers of folding cartons and labels, as well as containers.

Add to this mix the government's requirements for more detailed written information on a drug's content and dosage, as well as potential side effects, and you can see why an increase in print demand is forecast.

Pharmaceutical printing requires exceptionally clean conditions. Also, extensive amounts of information often must be printed on small packages or containers. This data must be printed clearly even when very small type is used, since it must be readable by people with poor eyesight.

Security is another major consideration since the right package must go with the right product. This task increasingly is controlled by bar coding, which matches the product to the package during assembly or filling. The bar code must be reproduced with maximum clarity for correct reading.

Traditionally, labels have been printed by rotary letterpress and rotary screen, and longer runs by gravure. Solvent-based flexographic printing virtually has been eliminated due to environmental considerations. Water-based inks can be used for simple line work, but can't offer the print sharpness necessary for fine text and four-color work, as well as gloss for that all-important shelf appeal.

Enter ultraviolet-cured flexographic printing or UV flexo, as it commonly is called. Combining the relatively low cost of flexo plate preparation with inexpensive narrow web printing presses and UV-curable inks has resulted in a printing process that produces high-quality, high-definition printing that is just right for the pharmaceutical market.

Interestingly enough, neither flexo printing nor UV-cured inks are new. Both have been around for many years. The new developments are equipment and material modifications that have brought the process to its present position.

UV inks have come a long way since their introduction in the 1960s. Materials in today's inks are more user-friendly and far less prone to cause skin irritation.

Most importantly, viscosities have dropped considerably with the introduction of new monomers, while cure rates have improved. Although the viscosity still is not as low as solvent- or water-based inks, it's much lower than offset or letterpress material. Therefore, these inks lend themselves to the anilox-type inking system found in flexo printing. When used with a reverse angle doctor blade, UV inks can deliver a sharp line or halftone print that is instantly "frozen" by the UV curing lamp, thus exhibiting none of the feathering found with water-based inks, while at the same time avoiding the polluting aspects of solvent-based systems.

Being 100 percent solids, UV delivers a heavier, dense film of ink that rivals rotary screen while producing superior graphics. In many cases, overprint coatings can be eliminated as UV inks exhibit improved gloss and scuff resistance compared to water-based printing systems.

The improved design of today's narrow web presses has lent itself to the marriage of UV and flexo technology. A good example of these presses is Comco's Cadet and Commander models. The modular layout of the press units makes plate changes quick and easy, two important requirements for short-run work. The drying units can be outfitted for hotair and/or UV curing. Their chill drum web support system makes the presses suitable for film printing where good support on extensible material is essential for close register work.

Comco has preinstalled brackets on each of its units to be UV ready. Lamp power ranges from 400 to 600 watts per inch, and the reflector rotates to become the cover for the lamp when the press isn't running. These lamps are relatively inexpensive and lend themselves well to flexo.

As stated earlier, the viscosity of UV flexo inks is considerably below that of letterpress and offset, but still much higher than inks conventionally used in flexo printing. It was, therefore, necessary to create a different anilox cell configuration to allow the more viscous UV ink to transfer efficiently at normal press running speeds. Operators also can make use of the reverse angle doctor blade when running these higher-bodied inks.

Substrates for pharmaceutical packaging run the gamut from pressure-sensitive labels, coated and uncoated instruction leaflets or "expanding" labels, to folding carton stock.

Other markets, such as the beverage and cosmetic industries, use the no-label look, which essentially is a film label applied to a bottle or plastic container so only the printed image can be seen. Examples include Bud Ice and Clearly Canadian in bottles, as well as Ivory dish detergent and Pert shampoo in plastic bottles. The pharmaceutical equivalent of the no-label look is used for serum pouches and syringe, in which dose levels can be seen through the label.

New films and adhesive have contributed to shift away from heat-seal application of labels to pressure-sensitive. Polyolefin facestocks such as co-extruded polypropylene/ polyethylene, with emulsion adhesive, rapidly are replacing vinyl and solvent adhesives. The new films lend themselves to plastic squeeze containers.

In many cases, the booklet approach for medical instructions mentioned earlier (originally patented by Denny Bros. in Great Britain) can start with a film base layer that anchors the booklet tot he product container. This layer can be applied on- or off-line and eliminates the need for separate insertion.

Coding of pharmaceutical products is of major importance when it comes to batch numbers, expiration dates, etc. Traditionally performed by hot stamping, it now is done by lasers. One problem was that polyolefin films are transparent to lasers. Now, Fasson films came up with a new film that contains a material co-extruded in the "sandwich" that, when activated with a laser, reacts to form a dark gray print that contrasts well with the white background.

The packaging market is estimated to be $80 billion, with flexographic printing having a 65 percent share. There are approximately 1,500 label printers. UV flexo constitutes a small part of that market so far, but is estimated to grow 20 percent to 22 percent annually for many of the reasons outlined earlier.

Many other markets exist that we have not mentioned because this report highlights the medical packaging market. But, it is clear that exciting new technology has entered the flexographic printing arena and ink companies need to ensure they keep in touch with the latest developments.

TERRY SCARLETT Contributing editor and president of Burntwood Industries (Marco Island, FL), a consulting company specializing in inks and coatings