“We will see increased use of bio-based materials“

Completely sustainable solutions are still rather rare in the paints and coatings industry. However, the academic world is quite active in this field. We spoke with Prof. Mats Johansson from the Royal Institute of Technology, Sweden, about current challenges.

From a chemist’s point of view, what are the biggest challenges facing you nowadays when you want to develop a bio-based coating?

Prof. Mats Johansson: There are several challenges to handle and this is probably one of the reasons for the rather slow progress in this area. I would say that there are also different routes to biobased coatings and they each impose different demands. One route is to replace currently used monomers with the same molecule but derived from a biosource. For example, a natural methanol might be used instead of fossil-based methanol in the production of polyols. In this case, it’s quite straightforward to use the bio-based system since it has already been validated in real applications. The sustainability aspect then comes down to how the biomethanol has been derived, i.e. if it compares positively in a life cycle analysis.

Another route is to replace existing systems with other components derived from a biosource and then to formulate a new system that replaces the fossil-based one. In this case, the new system must also be validated in the final application, meaning that an additional development step is needed.

From a purely chemical point of view, one big challenge is to produce biobased monomers of well defined composition. Bio-based monomers are normally obtained as mixtures, and purification steps normally increase the price.

Prof. Mats Johansson, Royal Institute of Technology, Sweden

Not every material that is bio-based is automatically sustainable. For example, you might be competing with the food chain. How might this be avoided?

Johansson: There are substantial efforts underway to address this issue through the use of side streams from current industries as a way of to avoiding this competition. These could, for example, be side streams from the paper and pulp industry, such as lignins and hemicellulose, that today are mainly used for energy recovery. There are also large-volume side streams from the food industry that offer potential in this respect. One should be careful, however, not to adversely affect the farm system with respect to food production if these streams are used outside the current system.

There are also geographical factors to consider. Conditions can vary substantially with location. There is a clear tendency for competition with food to be more severe in more densely populated regions.

The academic world seems to be very active in the area of bio-based materials, yet the coatings market is clearly dominated by conventional materials. Do you think, this is just a price issue?

Johansson: Price, of course, is one of the most important factors but I also think that there is an intrinsic delay factor in the length of time it takes to validate new systems. Some coating systems need to be warranted to last for up to 20 years and any totally new system therefore needs to be tested appropriately in order that such a warranty can be given. However, there are several new systems being introduced onto the market and I think we can foresee that this trend will continue.The oil price has fluctuated significantly in recent years and this may affect the introduction of bio-based materials in the short term. But I think that, from a longer perspective, we will see increased use of bio-based materials in coatings. One parameter that I also think will be of importance is potential changes in legislation and they are more difficult to predict.

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