“Suppliers are now introducing their bio-based materials instead of us having to ask for it

Formulating bio-based coatings can be a difficult task. You not only need bio-based raw materials that offer a comparable performance to regular raw materials but also a reliable and sustainable feedstock. We spoke with experts about both challenges. 

Castor oil

Finding bio-based raw materials for the formulation of coatings can be hard. For many years, there were only a small number of players that were trying to boost the usage of bio-based raw materials in the coatings industry. In the past years, however, this situation is changing.

“The availability of bio-based raw materials is getting better and better. For a few years, we have been able to see that more materials are on their way and that manufacturers and suppliers are introducing their bio-based materials instead of us having to ask for it”, explains Markus Lettau, Head of R&D at Auro Pflanzenchemie, a manufacturer of sustainable paints from Germany.

Markus Lettau Auro

Dr Markus Lettau is Head of R&D at Auro Pflanzenchemie.

However, even though it is improving, “the current raw material situation is not satisfying in terms of availability of renewable resource based products if it comes to water-based technology”, says Markus Dimmers, head of technical marketing at Alberdingk Boley.  

Industry more involved in bio-based coatings research

Both statements show that the situation is in flux. While some aspects are improving, others factors remain quite difficult still. “Actually, there are some projects of certain manufacturers to replace conventional additives, like dispersants, by bio-based versions”, says Markus Lettau from Auro and adds: “The situation has changed and not only universities and specialised institutes are our partners in research projects, even the industry changed their approach and we have found partners for the production of bio-based raw materials for our binder production.”

Markus Dimmers from Alberdingk Boley highlights specific raw materials: “One of the bio-based raw materials we use in synthesis is (modified) castor oil which offers various advantages compared to other sources. Thanks to its unique chemical structure, it reliably offers technical features like reactive OH-groups, double bonds and hydrophobic properties by nature.”

Markus Dimmers Alberdingk Boley

Markus Dimmers is Head of Technical Marketing at Alberdingk Boley.

He also says that the castor crop has advantages in being a very ethical resource, because of it’s environmental growing and harvesting conditions that are typical for it.  “In contrast to this, however, we learned that acrylate monomers as well as diisocyanates based on bio-materials are hard to find in consistent quality, acceptable price-performance ratio”, adds Dimmers.

Is bio-based coatings performance good enough?

When it comes to the performance both experts are of similar opinions. For Markus Lettau, the performance is no longer an issue. He states: “Our own binder puts us into the place to produce indoor paints which are at the same technical level as conventional products.” Lettau explains that this was not always the case in the past. “So, we decided, as a small company, to develop not only new products, even an own binder and the raw materials for the binder were the key for us to open new dimensions for our products.”

But of course, this is not necessarily an option for all paint manufacturers. Most companies will probably still prefer to get their raw materials from large suppliers. And certainly the performance of bio-based products differs, depending on what kind of chemistry one uses and what application the coating is designed for.

Same chemistry or new chemistry

“Bio-based resins can easily be equal in properties, especially acrylic based products as the building block can have the same structure but just using a renewable alcohol for esterification. In polyurethanes, this can be different and bio-based polyols could be even more hydrophobic than standard materials”, explains Markus Dimmers. And adds: “Depending on the final applications, these kind of PU systems have already been replacing standard crude-oil-based resins (e.g. EP based system) at a very reasonable market price.”

Markus Lettau also emphasises the classics: “Of course, we still use the classic raw materials of the natural paint industry as linseed oil and stand oils, as these materials are highly recommended in wood treatment varnishes. Regarding these classic applications, we still see that these materials are unbeatable compared to conventional products as they give a natural look and haptics, so the look and feel is at a level petrochemical products cannot reach.”

 By Jan Gesthuizen

Event tip

On 6-7 October 2020 international experts on bio-based coatings and raw materials will come together in Berlin to discuss latest findings and innovations in this area at the European Coatings Technology Forum | Bio-based Coatings. The event will follow a detailed hygiene concept to ensure safety of all participants. The early bird registration ends on 24 August.

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