UV-curing 100% solid systems - The key to quality and productivity
Bayer MaterialScience offers a large range of UV-curing raw materials for furniture, joinery and exterior wood coatings:
Urethane Acrylates
With urethane acrylates a high quality wood coating formulation can be finetuned to specific properties like flexibility, hardness, abrasion- and scratch resistance.
Unsaturated acrylic resins open the door to one of the most promising technologies: 100% solvent free UV curing coatings based on unsaturated polyester resins diluted with acrylic reactive monomers of the Desmolux® family. These products offer advantages over traditional unsaturated polyesters, while maintaining their advantages such as thick layer application, mattability, outstanding sandability and very good adhesion. With these products high solid coatings meeting the new VOC-restrictions can be formulated.
Reactive monomers are solvent-like substances that reduce the viscosity of the formulation. The coatings formulations can be applied and cured without any solvent evaporation and with the highest line speeds exceeding 20 meters per minute in some cases. Bayer MaterialScience offers a range of urethane acrylate resins that are ideally suited for roller coating applications. They are setting standards in many properties, especially for abrasion resistance.
Some unsaturated polyester resins in acrylic monomers
Hard, for clear topcoats and pigmented primers and topcoats; good sandability, adhesion and intercoat adhesion; improves scratch resistance of UV topcoats
Matte top coat for roller application with excellent balance of properties
(UV-reactivity / price) (Desmolux® VP LS 2381)
Monomer-free polyester acrylates
Desmolux® VP LS 2266 combines the advantages of the polyester chemistry with the chemistry of epoxy-acrylates: Low viscosity and high reactivity combined with a good hardness/elasticity balance. Desmolux® XP 2732 offers a very low viscosity of 2500 mPas, however, still allows to produce monomer-free coatings at 100% solids. Desmolux® XP 2733 is highly crosslinked and highly reactive for very resistant coatings. Desmolux® XP 2744 offers an excellent combination of chemical/mechanical resistance and flexibility.
Monomer-free amine modified polyether acrylate
Desmolux® VP LS 2299 is an amine-modified ether acrylate and shows the highest reactivity at a very low viscosity. This helps to overcome the oxygen inhibition. This product is suitable for reactive topcoats or as an additive oligomer to increase reactivity and reduce viscosity.
Waterborne polyurethane dispersions
Waterbased UV-curing coatings have gained substantial popularity during the last years. Large office furniture manufacturers are advertising their products on the merit of environmentally friendly low-VOC coating systems. Waterbased UV-curing polyurethane dispersions fullfill the important requirement of many large furniture companies to dispense with solvents in their production, and still be economical. Other companies of the industrial wood processing industry, like in window and door manufacturers have followed and recognize the virtues of these UV-curing systems. The high crosslinking density of UV-cured coating films makes it still possible to meet the highest quality standards the industry asks for.
UV-curing waterbased coatings are built up just like typical solventbased 2K polyurethane coatings through the combination of poly-isocyanates and polyols. However, there is a major difference: the time consuming step - the chemical reaction of the components - has already taken place in waterborne systems when the coating is applied. It is possible to produce high-molecular physially drying dispersions as well as non-physically drying emulsion grades, that can be additionally cured by UV light. For the crosslinking on the substrate UV-curing polyurethane dispersions just need a short reaction time under UV light, so existing coating lines being switched from solventborne 2K polyurethane coatings to waterbased UV systems are typically running faster than after the conversion.
Additional advantages to be considered are lower energy consumption and overspray recycling. Material that has been oversprayed during the coatings process can be recycled by up to 80%, with the obvious advantages for the environment and the economics.
Examples of waterbased UV-curing raw materials for wood coatings:
Clear coat for spraying, semi-gloss (Bayhydrol® UV 2282)
More starting formulations for waterbased UV-curing wood coatings are available on request.
Two new UV-curing dispersions for exterior wood applications and primers
Bayhydrol® UV XP 2690 for exterior wood applications Bayhydrol® UV XP 2690 was developed specifically for exterior wood applications. Coatings based on this polyurethane dispersion are noted above all for their outstandig weather resistance, a claim that has been confirmed in a study by the Fraunhofer Institute for Wood Research (WKI), which shows that the wood surface remains absolutely free of damage during weather exposure and meets the requirements of DIN EN 927-3. The test results also show that when used outdoors, the timber can withstand the elements for eight years, before re-coating is required. An additional advantage is that Bayhydrol® UV XP 2690 is suitable for both clear coats and pigmented top coats.
Bayhydrol® UV XP 2687 for wood primers and clear coats
The second addition to the Bayer MaterialScience range is Bayhdrol® UV XP 2687, which has been developed specifically for use as a primer. The product is recognized for its outstanding grain accentuation and adhesion to all wood types, even those containing oil. The polyurethane emulsion has a high solids content, which allows higher film thicknesses to be achieved in a single application. Due to its excellent resistance properties and high degree of hardness, it is also suitable for clear coats and can be formulated for both spray and roller application.
Get more information on UV-curing coating systems here:
Bayer MaterialScience offers a large range of UV-curing raw materials for furniture, joinery and exterior wood coatings: