Coatings manufacturers are always looking for an edge when it comes to formulating their products. Whether they are manufacturing coatings for the automotive and aerospace market, industrial or wood coatings and furniture, or other products, coatings formulators are developing materials that offer advantages for their customers.
In recent years, radcure products have gained in popularity among coatings makers. There are a number of reasons for this. Environmentally, UV and EB coatings emit virtually no volatile organic compounds, and their instant cure through light eliminates solvents and drying. As a result, manufacturing costs may also be lower. UV and EB coatings also offer improved properties, such as higher gloss and better resistance.
At the recent Advanced Materials Conference at uv.eb WEST 2013, coordinated by RadTech and held in Redondo Beach, CA, speakers from various coatings fields offered their thoughts on how energy curing is changing the way they do their work.
RadTech officials reported that attendance was up more than 50% from its last event, demonstrating the increased interest in UV and EB curing.
Take, for example, clearcoats for the aerospace market. Rick Baird of Boeing Research & Technology noted in his talk on “Progress Toward a Heat-Resistant UV-Curable Clearcoat for Aircraft Exteriors” that present paints show discoloration in areas subjected to high heat (~300°F) in service.
Baird added that a heat-resistant clearcoat would act as barrier to oxygen and moisture, and slow down the degradation process. He said that a very fast cure of clearcoat would be needed to minimize flow time hit, and UV may be ideal for the market.
“UV cure delivers the best cure time, as thermally-curable paints are too slow,” Baird noted. “Curing takes seconds, as the overall cure depends on how quickly the surface can be scanned with UV lamps, while the best thermal cure takes hours. Paint achieves full cure during UV exposure, with no wait after UV exposure to fly, and there are reduced hazardous emissions, with nearly zero VOCs.”
Baird noted that the cure system requires capital investment, although small affected areas can utilize off-the-shelf portable systems, and added there are a few basic requirements.
“There is a need for a clear formula with superior heat resistance and acceptable batch-to-batch uniformity that meets Boeing’s exterior decorative spec,” Baird said. “Spray properties need to be close to thermally-cured paint, as it is OK to heat paint, and a cure process that minimizes equipment complexity, accomplishes surface and through cure and meets safety requirements and also provides for overspray cure. It must also be a cost-competitive process, in that flow time advantages must offset capital costs.”
Industrial finishing is another area of interest for radcure coatings, and Ben Curatolo of Light Curable Coatings, a UV coatings specialist, discussed resistance properties in his talk on “UV Technology for Corrosion Resistance.”
“UV coating technology is widely used for decoration and protection in many different applications in a wide range of industries,” Curatolo said. “The suitability of UV technology for high performance corrosion resistant applications has now been demonstrated industrial and aerospace applications.”
The U.S. Government Accountability Office (GAO) believes that there is a $400 billion annual cost presently due to corrosion in the U.S., and substituting hand-held UV curing systems for the epoxy and polyurethane paints presently being used can play an important role in reducing these costs.
“Just as any surface can be painted by a few individuals spraying or rolling, a UV coating can be applied and cured by painting and when following with a UV lamp,” Curatolo said.
Along those lines, Bill Schaeffer of Sartomer USA offered his thoughts on “Radiation Curable Components and Their Use in Corrosion Resistant Applications,” comparing aliphatic (ALUA) and aromatic (ARUA) urethane acrylate oligomers.
“UV/EB curable coatings based on aromatic backbone structure resist corrosion better than their aliphatic analogs,” Schaeffer concluded. “Aromatic urethanes are generally superior to aliphatic, but there are exceptions based on backbone structure.”
Dan Montoney of Rapid Cure Technologies, which develops and manufactures unique resins, coatings, inks and adhesives, discussed the field of metal coil coatings in his presentation on “UV/EB Curable Coatings for Metal Coil Coating Application.”
Montoney said that the metal coil finishing field has yet to widely adopt UV/EB curing, in spite of its advantages. One key disadvantage to UV/EB curing for metal coil is its overall cost vs. performance, and Montoney noted that there is a lack of real world and accelerated testing data. He does believe that EB curing has a place in the market.
“EB curable raw materials and formulations have been shown to meet or exceed many coil coating performance specifications,” Montoney said. “However, all evaluation must be carried out on actual substrate to prove performance and achieve a high confidence level. EB curing is a viable finishing technology for coil coating and provides numerous benefits.”
Metal coil coatings were also discussed by Karl Swanson of PCT Engineered Systems and Kevin Joesel of Fusion UV Systems, who collaborated on “UV/EB Technology for Metal Coil Coatings.”
“UV/EB coil coating technology offers substantial energy savings and carbon footprint reductions, but challenges remain with coating costs and performance,” Swanson and Joesel noted. “The best fit for new UV/EB coil coating installations may be for fabricators looking to produce their own coated metal.”
In-field curing is an opportunity for radcure coatings. In his talk on “Advantages of UV Curing in Composite Manufacturing,” Dr. Jonathan Shaw of Cytec Coating Resins noted that UV technology is moving out of the plant and into the field in areas such as wood, concrete and vinyl composition tile (VCT), and he sees similar possibilities for composites.
“UV composite curing is starting to move that way as well,” Dr. Shaw said, pointing to in field repair of concrete bridges and supports and wind turbine blades. “The driver is fast return to service.”
There are upcoming opportunities to see how UV/EB can be used in the coatings field. With a grant from the New York State Energy Research and Development Authority (NYSERDA), RadTech, in partnership with the State University of New York College of Environmental Science and Forestry (SUNY-ESF) Institute for Sustainable Materials and Manufacturing, will hold uv.eb EAST 2013 from Oct. 1-2, 2013 in Syracuse, NY.
For more information, check RadTech’s website at www.radtech.org.