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Gapen on UV

Gapen on UV

By Darren Gapen

About Darren

Darren has worked in the printing industry for 30 years and spent more than 12 years at two of the nation's leading high-end commercial printers: Bradley Printing in Des Plaines, IL, and Williamson Printing Corp. in Dallas, TX. During that time, he operated conventional and UV 40˝ sheetfed presses and also successfully managed a $15-million pressroom equipment transition. Darren also was Lead Press Instructor for Heidelberg, where he directed specialty equipment startups and was involved in all aspects of the printing process by teaching both instructor and pressroom employees.

In addition, he served as a troubleshooter for various printing companies in the U.S., Canada and Mexico. As operations manager for a start-up specialty folding carton company, he played a key role in achieving more than $6 million in sales within two years. Currently Darren is president of D.G. Print Solutions, a consulting firm that supports printing companies of all sizes. He specializes in growth development planning, pressroom color management and pressroom training through specialty print applications.

 

Printing Plastics not a Slam Dunk with UV

By Darren Gapen | Posted on August 19, 2010
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I spent last week at a customer completing some testing on various plastic substrates with the goal of achieving the best possible result for one of its new clients. We tested everything from inks and coatings to lamp energy, settings and placement. All of which had an effect on the final outcome.

The objective is to use a sufficient amount of energy to dry the inks correctly, but not to distort the plastic so it looks like a potato chip.

You have to keep in mind that just because you have invested all that money into UV capabilities, it doesn’t give you the guarantee that you will have instantaneous success with printing on non porous substrates.

Dyne levels of the plastics along with chemistry compatibility continue to have a large effect on successful adhesion and end result. It continues to be as important as it is with conventional printing.

You will realize the end result much quicker as the sheets fall into the delivery, but if you don’t take into consideration the complexity of the project at the finishing end, the outcome could be devastating.

It's one thing to print a transparent menu for your local hotdog stand or a liquor advertisement for your local grocery store window, but it’s another matter entirely to create a packaging piece that not only scores, folds ands glues but also gets a coupon attached to the outside of the carton with a removable adhesive.

I can assure you that if the ink doesn’t stick while you’re running the job, it’s not going to get a great deal better after the fact. You have to verify the adhesion on press. You may use a UV coating to cover the sheet, but is this process giving you the feeling of a true or false adhesion? Chances are, false.

Most ink companies manufacture a series of UV inks that are formulated specifically for plastics, much as they do with the conventional process. Many times this set of ink will give you the best results. I realize this constitutes an additional wash up, but the alternative is the job having to be rerun on a substrate that could cost upwards of $2 per each 40˝ sheet.

What costs less—the testing of chemistry and a possible additional wash up or the plastic itself? You decide.

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Most Recent Comments:
Ron Matiunas - Posted on March 03, 2011
I sold UV and EB OPVs for what was Morton Chemical. All of what was said above is true, but static control and edge welding were a major problem for plastics and paper as well
Bryan Ascher - Posted on August 23, 2010
You mention in your article that you have tried different energy levels for the UV lamps but have you confirmed that the lamp is producing energy in the correct spectral range. You can end up with a very high UV output but it may be curing at 365nm, when it should be at 400nm. We compare it to shining a flashlight on a door lock so you can insert the key. If you have a ton of light but it is focused to the right or left of the lock you still have a lot of light but not where you need it. During production, all lamps have mercury added, but various other additives can be added to the lamp such as iron or gallium to shift the spectral out put thus insuring you have the correct spectral out put to match the ink for the proper cure. Ink manufacturers in most cases can provide you with an SED (Sectral Emission Distribution) curve which tells you at exactly what wavelength the ink cures best.
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Archived Comments:
Ron Matiunas - Posted on March 03, 2011
I sold UV and EB OPVs for what was Morton Chemical. All of what was said above is true, but static control and edge welding were a major problem for plastics and paper as well
Bryan Ascher - Posted on August 23, 2010
You mention in your article that you have tried different energy levels for the UV lamps but have you confirmed that the lamp is producing energy in the correct spectral range. You can end up with a very high UV output but it may be curing at 365nm, when it should be at 400nm. We compare it to shining a flashlight on a door lock so you can insert the key. If you have a ton of light but it is focused to the right or left of the lock you still have a lot of light but not where you need it. During production, all lamps have mercury added, but various other additives can be added to the lamp such as iron or gallium to shift the spectral out put thus insuring you have the correct spectral out put to match the ink for the proper cure. Ink manufacturers in most cases can provide you with an SED (Sectral Emission Distribution) curve which tells you at exactly what wavelength the ink cures best.