Michael addition curable coatings from renewable resources with enhanced adhesion performance
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Michael addition curable coatings from renewable resources with enhanced adhesion performance Bart Noordover, William Liu, Eric McCracken, Bill DeGooyer, Richard Brinkhuis, Florian Lunzer
Ó American Coatings Association 2020 Abstract Novel malonate-functional polyesters from biobased and potentially biobased monomers were developed and cured through the base-catalyzed carbon-Michael addition reaction with acryloyl-functional oligomers. Both drop-in monomers, such as fully biobased diethyl malonate, and alternative raw materials, such as isosorbide and vegetable oil, were introduced. Isosorbide-based polyesters show improved performance to humidity in terms of adhesion on epoxy-amine primer, while vegetable oil-containing resins lead to improved coating appearance due to better flow and levelling. This study demonstrates that biobased malonate resins, having renewable contents up to 53%, offer attractive performance benefits in 2K RMA paints. It is anticipated that, with the development of additional fully biobased polyols, renewable contents in excess of 80% can be achieved. This paper was presented at the 15th Coatings Science International Conference on June 24–29, 2019, in Noordwijk, the Netherlands. B. Noordover (&) Allnex The Netherlands B.V, Synthesebaan 1, P.O. Box 79, 4600AB Bergen op Zoom, The Netherlands e-mail: [email protected] W. Liu Allnex Resins China Co. Ltd, 127 Taishan Road New District, 215129 Suzhou, China E. McCracken, B. DeGooyer Allnex USA, 4730 Crittenden Drive, Louisville, KY 40209, USA R. Brinkhuis Allnex The Netherlands B.V., Corporate Innovation Group, Nieuwe Kanaal 7 N, 6709PA Wageningen, The Netherlands F. Lunzer Allnex Austria GmbH, Leechgasse 21, 8010 Graz, Austria
Keywords Michael addition, Curing, Isocyanate-free, Biobased, Adhesion
Introduction Recently, a Real (or: Carbon) Michael addition (RMA) chemistry-based high solids 2K coatings system was developed that is suitable for a range of applications on metal, primer, concrete, wood and plastic substrates.1–3 This technology facilitates improvements in productivity, energy savings, an improved EH&S profile and an overall enhanced property profile in terms of chemical resistance, mechanical performance and durability. In this basecatalyzed system, polyester RMA donor resins having activated C–H functionalities are reacted with acryloylfunctional oligomeric RMA acceptors (Scheme 1).4,5 By using a blocked base catalyst combined with a kinetic control additive package, the pot life and drying time can be decoupled, meaning that a long pot life can be combined with fast curing. Scheme 2a shows how the strong base (OH ) can be blocked by a dialkyl carbonate. Subsequent reaction of the alkyl carbonate anion with an acidic compound leads to decarboxylation of the protonated alkyl carbonate (i.e., an instable carbonic acid) and formation of a strong base which can perform a Michael addition reaction (Scheme 2b). Note that this deblocking step is an equilibrium reaction. In a paint container with a low surface to volume ratio, ev
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