Aug 31 2007
Because they combine the excellent property profile of polyurethane systems with the environmental friendliness and economy of UV technology, radiation-curing coatings based on urethane acrylates have been extremely successful in recent times. Experts from Bayer MaterialScience's Coatings, Adhesives, Sealants Business Unit have now developed an allophanate-based binder for such coatings that is free of reactive thinners. "Desmolux® XP 2666 offers our customers maximum freedom in formulating their coatings," says Dr. Wolfgang Fischer, an expert for UV-curing coating materials at Bayer MaterialScience. Because it is free of monomers, the binder can be used for low-VOC coatings and printing inks.
Desmolux® XP 2666 also has a high level of reactivity due to its well coordinated double bond density and functionality. "As a result, coatings based on this product are not only resistant to chemicals and mechanical stress, they also have an excellent weather stability," says Fischer. The new aliphatic urethane acrylate can be used to coat a variety of substrates, including plastic and metal.
Some innovative examples demonstrate the versatility of the new product:
incorporated in special overprint coatings, for example, it affords effective protection to in-mold labels. Unlike conventional labels, their in-mold counterparts are not bonded onto a plastic but, after a protective coating has been applied, are backmolded with a thermoplastic for the production of such articles as bottle crates. Desmolux® XP 2666 is also playing an important part in the development of clear coats for automotive repair. Through UV-A radiation, such finishes cure in just a few minutes, which means that, with systems of this kind, workshops can offer their customers the special service of a complete car repair coating in just one day.
Coatings based on Desmolux® XP 2666 are noted for their optimal combination of hardness, elasticity and good adhesion. The new urethane acrylate can thus also be used for UV-curing direct-to-metal coatings. The experts at Bayer MaterialScience have tested such one-coat systems with regard to adhesion and corrosion protection and obtained very good results.