Lignin binders for adhesives and printing links - Bio-based and formaldehyde-free

 
The range of starting materials that can be used as monomers for the synthesis of bio-based binders is growing every year and includes vegetable oils, sugars and different products of bio-technological processes. However, few are as promising and at the same time as challenging as lignin. As one of the main components of wood, it is the biggest source of aromatic molecules in nature and offers unique opportunities to synthesize high glass transition temperature polymers. Furthermore, as a by-product of the paper-making process, it is available in large quantities without any competition in the food production value chain. However, its low reactivity and heterogeneous composition mean that material uses have been limited to partially replacing phenol in phenol formaldehyde adhesives. In this talk, different ways to incorporate lignin in polyester and polyether binders are presented. The synthetic method allows the tuning of important properties such as the viscosity, the solubility and the melting behavior of the lignin binders, and avoids the use of formaldehyde entirely. Thus, lignin-based polymers were formulated into adhesives and printing inks. Results of performance testing of these products will also be presented. The developed polymers show promise for a range of applications, and for finally creating a high value use for lignin.