Valued for its superior finish, speed, efficiency and environmental benefits, the use of UV and EB coatings technology continues to gain favor in applications as diverse as automotive OEM and refinish, wood flooring and cabinetry and aerospace. And while market growth slowed a bit when the economy went south, signs are looking up for rad-cure.
"For several years leading up to the recent recession, UV and EB had been recording double digit growth rates," said Gary Cohen, executive director, RadTech International. "After a short lull in the economy, our members are once again pointing to the potential of double digit growth."
Leading rad-cure coatings firms agree. "UV curable coatings will continue to grow," agreed Tim Tanner, UV product manager, Red Spot Paint and Varnish Co. "We expect the UV coatings market to grow at a rate of 10-15% per year for the next five years. This will be a combination of growth with existing business as well as new applications."
Fueling this growth are R&D efforts by suppliers to the rad-cure industry that have led to improved UV and EB technologies, as well as increased use in a number of applications. "With a big increase in inquiries during the last few months and the acceleration of development work in UV/EB by suppliers, we seem to be approaching breakthroughs on a few fronts–automotive applications, aerospace and cabinets, for example," said Cohen. According to Cohen, various industrial applications are projected to post double digit growth rates over the few years.
"As the development of UV coating raw materials continues and the application techniques become more operator friendly and cost justifiable, we anticipate seeing growth in the coating and finishing markets for UV across all types of products including glass, metal, wood, plastic and composites," said David Hagood, UV market development manager coating and finishing group, Nordson Corporation.
According to Gary Freelin, group leader, release coatings, Degussa, new applications for rad-cure exist in integrated business and shipping forms, incorporating security features such as RFIDs, holograms and stacked labels. "There will be a slow shift to linerless applications, use of less expensive substrate materials, such as MF, MG paper and thin film as equipment for handling is developed," he said.
Automotive is another area ripe for greater use of rad-cure, according to Bill Bayer, vice president, business manager-coatings and graphics, Cytec Surface Specialties. However, "this market is very difficult to enter because of the very huge demand it requires of applied finishes. Due to the many advances that rad-cure coatings and equipment have made in the past 10 years, the use of rad-cure coatings in automotive will begin to increase," Bayer said.
| Red Spot's application center, dedicated to developing radiation-curable coatings for plastics, is one of the largest in the world. |
One key advantage of using UV coatings for automotive refinish is fast cure speeds. "In automotive refinish, cycle time is a major cost block, and waiting for coatings to cure is a big part of this," said Simon Lord, marketing manger, business line coatings, Ciba Specialty Chemicals Corp. "It's also a source of potential defects from particulates landing on wet coatings. UV curing could drastically reduce both cycle time and defects. This application is just ripe for adopting UV cure, as soon as the job shops are comfortable with the modest investment in the lamps."
When it comes to the automotive refinish market, "speed is the name of the game," said David Diehl, manager, corporate technology initiatives, PPG Industries. For this market, PPG has launched Speedprimer, the first UV primer in a can. "Speedprimer has been well received," said Diehl. "Unlike conventional coatings that can take from 12-24 hours to cure, Speedprimer cures within minutes."
Automotive parts manufacturers also stand to benefit from UV curing technology. "The success of hardcoats for polycarbonate lighting is testimony to the potential," Lord said. Lastly, the gel coat and composites industry is on the cusp of adopting UV cure as a way to help address regulatory issues while also increasing productivity."
UV coatings for appliances is another potential growth area. Red Spot's latest product is Stainless BMC, a UV topcoat for appliance parts that can be used in place of stainless steel metal. "The end product is a BMC plastic handle with chrome or aluminum metallizing for the stainless look and then coated with our UV topcoat to protect the plastic and metal from abrasion, chemicals and other possible damage," said Tanner.
Waterborne And 3-D
Areas of increasing interest for rad-cure coatings are water-based UV coatings and the ability to cure three-dimensional objects. "In terms of supplier developments, the popularity of water-based UV formulations is growing rapidly, while equipment suppliers have recently developed new innovations such as the use of robotics, CO2 inerting environments and LEDs as a UV light source," said Cohen of RadTech International.
"We expect to see the market grow in liquid UV coating and curing of many three-dimensionally shaped products," said Hagood. "The advantages of UV material, including 100% solids, zero VOC coatings, lower energy costs to cure parts compared to other liquid and powder coatings, smaller footprint, less work in process, and many others will provide potential users with a cost competitive solution compared to other existing technologies like solvent- and water-based coatings or powder coatings."
Companies continue to address 3-D curing issues. "Traditional UV has required direct illumination of the substrate by the UV energy source, which has limited the technology to flat surfaces," said Tom Hall, business manager-performance chemicals for coatings, BASF Corp. BASF's solution is the Larolux process, a new UV system to coat complex, three-dimensional objects.
The system employs coatings made with BASF UV curing agents and UV light in a curing oven that contains a carbon dioxide atmosphere. When the oxygen content in the gas surrounding the parts is low, the UV dose can be reduced to such an extent that simpler, less expensive lamps can be used, and simple reflectors can illuminate three-dimensional objects. Under these conditions, thorough curing is independent of the part's geometry. In other words, three-dimensional parts that were impossible to cure using traditional UV air curing techniques can be cured using the Larolux process, according to the company.
The Larolux process opens up UV curing to applications in the medical device, automotive parts, aerospace and sports equipment markets, according to Hall. "Also, the lower operating temperature in the Larolux process allows formulators greater flexibility to develop coating systems for temperature sensitive substrates that previously were not possible to cure without damage to the substrate," Hall added.
Equipment suppliers are also working to develop technology to allow more complex substrates to be coated and successfully cured. "We have been working on technology to coat and cure three-dimensional shaped products," said Hagood of Nordson. "We are also working on the ability to UV cure using moving lamps, for more flexibility in curing difficult shaped parts."
Photo-latent bases is another area garnering attention, according to Lord of Ciba. "The advantage of these materials versus free-radical based systems, is that they suffer less from oxygen inhibition, and versus photo-generated acids, they can be used with hindered amine light stabilizers, to develop durable outdoor systems," he said.
R&D Efforts Pay Off
By zeroing in on R&D, suppliers have launched a number of new UV/EB products featuring improved performance characteristics that coatings manufacturers demand.
"Besides security of supply and price stability, most customers are seeking lower viscosity products with good reactivity and adhesion," said Steve Lundstram, general manager, Rahn USA Corp. "On top of this basic wish list comes specific needs like flexibility, abrasion, scratch, chemical resist and other properties for a good application."
Degussa is offering a complete line of cationic curing release coatings, Tego RC 1400 series, and two coater-ready free radical curing release coatings for alternative paper grade release liners. "We have also introduced a more efficient, cleaner photoinitiator for the free radical curing products," said Freelin.
Cytec Surface Specialties has launched a number of new products for the market, adding two new waterborne UV-curable resins for wood coatings to its Ucecoat line.
Ucecoat 7849 is designed to cost-effectively meet the requirements for wood flooring, furniture and cabinetry topcoats, according to the company. It offers good adhesion to a wide variety of woods, cork and paper, and provides good flexibility, stain and scratch resistance, according to the company.
Cytec Surface Specialties' Ucecoat 6558 is a waterborne aliphatic urethane acrylate for primer formulations. Depending on the substrate and coat weight, it offers the advantage of potentially eliminating the flash-off step since the water can be partially absorbed into the wood, and mostly evaporated by the heat of the UV lamps.
New products from BASF include Laromer LR 8949, a water-based aliphatic urethane acrylate oligomer for spray applications that is both hard and flexible; Laromer LR 9004, a tough polyester acrylate with good adhesion that is economical to use; and Laromer PO 9026V, a polyether acrylate oligomer containing nanoparticles that impart a unique scratch resistance to the coating, which is particularly useful for flooring coatings.
Shamrock Technologies offers its Everglide and Ultraglide series of wax dispersions for UV coatings. The products are designed to improve surface slip and rub properties. New nanofilm and microfilm powders were developed for gloss reduction properties, while also enhancing abrasion resistance for UV coatings. "We are also introducing a new line of texturing agents to add to our Texture series, which we are featuring at the European Coatings Show," said Joon Choo, vice president, marketing, worldwide, Shamrock Technologies.
VEctomer 1312 is the latest product from Morflex Inc. It offers a unique multi-vinyl ether functionality, in which, four terminal vinyl ether groups are available to react. "In practice this allows the UV/EB formulator to develop superior coatings and adhesives that are highly crosslinked," said John Johnson, market manager, Morflex Inc. "This results in outstanding hardness development in UV/EB coatings for example and toughness."
Rahn USA reports it has added a number of new monomers for various applications and a hexa-functional aromatic urethane acrylate for coating applications.
With the growing interest in water-based, UV-curable polyurethane dispersions, Ciba Specialty Chemicals recently introduced Ciba Irgacure 819 DW, a dispersion of bis-acyl phosphine oxide (BAPO) photoinitiator. To achieve excellent through cure with minimal residual color in pigmented coatings, Ciba Irgacure 2100 and 2022 were recently launched as high value liquid photoinitiators, according to the company.
Suppliers of UV/EB curing equipment have also been busy developing new products. EIT Instrument Markets has several profiling instruments, including UV MAP Plus and Power MAP. UV Map Plus measures one bandwidth and UV PowerMAP measures four different UV bandwidths simultaneously. These units can profile the entire UV system and identify what is occurring. The data screen shows energy density in joules/cm2, peak irradiance in watts/cm2 and temperature. Users can determine the energy density and peak irradiance of an entire run or use cursors to bracket smaller areas of the graph and see what the numbers are for that particular section. In a multi-lamp system, users can bracket one of the lamps to find out information under any designated lamp.
New this year from EIT is 3DCure, which allows users to obtain feedback from up to 32 UV sensors simultaneously (joules/cm2 and watts/cm2) on any multi-dimensional part. The results can be seen on the supplied Cure3D software. Users can verify the results of their UV system's exposure at all points at the same, saving hours of adjustment, according to the company.
Nordson Corporation has recently released a full line of microwave-powered UV curing lamp units to complement its existing products. "These new products can be used in most any UV application," said Hagood. "One big advantage of these units is less heat transfer to the substrate being cured, thereby being ideal for heat sensitive substrates. Also, due to the modular design, they are great for curing three-dimensional shaped products, which is a market with high growth potential."
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