UV-curable polyurethane dispersions (UV-PUDs) are a well-established and commercially successful class of products because of their combination of low environmental impact, range of achievable properties and ease of use. Important end-use applications for UV-PUDs include factory-applied wood coatings, field-applied coatings on concrete, wood or vinyl flooring, and protective coatings on plastics. All of these applications require high degrees of hardness plus scratch and abrasion resistance. PUDs made from renewable raw materials are also well known (including some UV-curable varieties), but are generally based on vegetable oil derivatives and, even after UV curing, are too soft for the applications mentioned above. This article discusses unique new UV-PUDs containing a high percentage of renewable carbon that have properties suitable for use in high-performance coatings.
UV-PUDs combine attractive aspects of two environmentally friendly coating technologies – waterborne and UV curing. In addition to the sustainability aspects, UV-PUDs deliver a unique combination of performance attributes that combine some of the best features of conventional waterborne and 100% solids UV coatings.1-3 The sustainability and performance of UV-PUDs has led to their commercial success and high market growth rates over the past several years. Use of renewable or biobased raw materials in UV-PUDs can bring another level of sustainability to this technology. There are many reports of UV-PUDs partially made from renewable material,4-7 but many of these are based on vegetable oil derivatives, with the final coatings being relatively soft and lacking some properties needed for high-performance coatings such as hardness, water resistance, stain resistance and scratch and abrasion resistance.