Novel Waterborne UV Curing Acrylic Dispersions for High Performance Kitchenand Furniture Coatings

Even though still a lot of solvent-borne coatings systems are being used for industrial wood-coatings (table 1)1 , environmental concerns about the use of solvent-borne wood coatings are causing a technology shift to VOC compliant binder technologies. Radiation curing coatings based on acrylic oligomers and monomers or unsaturated polyester diluted in styrene, find their main field of application in the coating of flat surfaces by roller. When threedimensional substrates need to be coated, quite often an organic solvent such as butyl acetate is added to the UV-coating rendering it sprayable. Needles to say that the VOC emissions form these sprayable UV-curing coatings are comparable to that of conventionally curing solvent-borne coatings. Over the last years water-borne binder technology is getting wide-spread acceptance as an alternative to solventborne or conventional radiation curing coatings. The main technology used nowadays in water-borne industrial wood-coatings is low temperature curing acrylic dispersions. The cure may be brought about by a self-crosslinking mechanism or by an external crosslinker such as a polyaziridine or a polyisocyanate. When an external crosslinker is used the coating usually is a two component system with a limited pot-life. Waterborne two component coatings are usually preferred for applications where a superior stain and chemical resistance are required. A good example of such an application is coatings for kitchen cabinets. The main reason why two component systems are used is that they allow for a much higher crosslink-density in the cured film compared to the one-component systems. The crosslinkdensity is directly related to the stain and chemical resistance. Two component coatings however suffer from their limited pot-life. That is one of the main reasons why another VOC compliant technology, water-borne radiation curing, has recently been quite successful in the finishing of wooden surfaces that require excellent stain and chemical resistance.