Originally Published MPMN January/February 2008

BREAKTHROUGHS

Color Change Answers Question, ‘Is It Cured?’

Stephanie Steward

For more than 30 years, ultraviolet (UV) light curing has been used in bonding applications. Engineers have always asked two questions:

How do I know that I’ve dispensed a sufficient amount of adhesive in the prescribed area, and how do I know when it is fully cured? After several years of conducting internal research and testing, Dymax Corp., an adhesives and light-curing systems provider, has developed two colorful technologies—See-Cure and Ultra-Red Fluorescing—that help to finally answer these questions.

Instead of applying a clear adhesive to clear plastic and waiting for test results to confirm whether the right amount of adhesive was applied and fully cured, adhesives featuring the See-Cure technology are blue so they are easily visible when applied. The blue color fades as the adhesive cures, and turns completely clear upon full cure. “The See-Cure color-change or color-transition product will allow [engineers] to zero in on the right sequences, the right timing, a lot faster because they can use it as a guide. Once the adhesive is in place, they can use it as absolute visual verification that the process continues to work,” says Richard Golebiewski, senior vice president, global marketing, at Dymax. The color does not affect a product’s sterilization or biocompatibility.

Responding to requests for visual assurance of UV cures, the company initiated an internal research and development project several years ago, but found there wasn’t enough new technology at the time in terms of raw materials to make it work. According to Golebiewski, unsuccessful attempts to produce a color-changing curable adhesive had been made in Europe. “The older technology did not provide 100% assurance,” Golebiewski says. “There were issues with the color returning, and where the color would fade and the product would not be cured.” Uncured adhesives, he says, can be toxic and can lead to component failure. “The liability is tremendous. We’re talking about human life. That’s why we’re saying that See-Cure is the first practical visible cure indicator,” adds Golebiewski.

See-Cure isn’t meant to replace other cure-verification processes, but it does give engineers and manufacturers a new level of accuracy and confidence when applying adhesives, curing adhesive bonds, and ultimately confirming precise adhesive placement and secure bonds. These blue adhesives also produce a different wavelength than transparency does, which can be analyzed with inspection equipment. A safety feature of See-Cure is that the color transition time is deliberately set to occur after the adhesive is completely cured.

Dymax developed Ultra-Red in response to another customer need for an easier way to visually verify inspection of the bond-line area when applying adhesives. Typically, when exposed to UV light, adhesives are clear and most plastics naturally fluoresce blue. Clear or blue-fluorescing adhesives, which the company also offers, can be difficult to distinguish or inspect on blue-fluorescing plastics, such as PVC or PET. “The [Ultra-Red] provides the adequate contrast that is necessary to really pick up the subtleties of potential leak paths or placement of the adhesive,” Golebiewski says.

Dymax Corp., Torrington, CT
www.dymax.com

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