Binder for Paints Based on Lignin

Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Bremen, Germany, have succeeded in producing a paint primer based on lignin, which can be extracted from plant residues, for example. It is free of raw materials made from petrochemicals and has a significantly improved CO₂ footprint.

Fossil resources are scarce, so there is great demand for raw materials that can not only replace petrochemicals, but are also greener and have a smaller CO₂ footprint. Of particular interest are raw materials that are not in competition with the production of foodstuffs or biofuels, yet are available in large quantities –like lignin, which is the most abundant natural material apart from cellulose. Lignin is, for instance, a by-product of paper manufacturing but is also produced in large quantities as a waste product in bioethanol production.

Lignin has often attracted the attention of scientists when developing alternatives to petrochemicals. However, due to its challenging properties and the complex production of a substance that always reacts in the same way, use of wood pulp has up until now not made a breakthrough. "Most previous approaches were based on producing lignin monomeric starting materials, which always have the same properties. Due to the different composition of the starting material, this is quite complex," explains Yvonne Wilke from Fraunhofer IFAM. "We took a different approach by standardising and modifying the whole substance. This gives us a raw material that we can say is always the same within certain limits." The result is a primer that has key properties such as corrosion protection, adhesion or application capability comparable to primers based on raw materials made from petrochemicals.