An alternative and biobased crosslinking system for coatings
Solvent-based coatings are usually based on acrylics, alkyds, polyurethanes, polyesters, melamine- or epoxy-resins. Many of the traditional crosslinking systems present drawbacks such as use of toxic and volatile compounds. We know that aldehyde functions react with phenolic compounds to form three-dimensional networks with excellent moisture resistance, durability, chemical stability and also thermal stability. Therefore, this reaction is an interesting candidate as crosslinking system. However, most of monomeric commercial aldehyde compounds such as formaldehyde, glyoxal or furfural are classified as Carcinogenic, Mutagenic and Reprotoxic chemicals (CMR). Moreover, monophenolic compounds such as phenol are also classified as CMR chemicals.
We developed an alternative, free from toxic chemicals and biobased crosslinking system for coatings using the aldehyde function reaction with phenolic compounds1.
To avoid toxicity issues, we designed innovant acrylic-styrenic oligomers bearing reactive aldehyde functions. Those oligomeric-size polyaldehyde compounds have reduced volatility, reduced toxicity and do not release formaldehyde. Also our research team has a strong background on biobased phenolic compounds chemistry. Hence, we selected non-toxic and biobased phenolic compounds. We studied the nature and efficiency of crosslinking reactions of model polyaldehyde oligomers with biobased phenolic compounds. Innovant polyaldehyde macromolecular compounds with different aldehyde function concentrations were synthesized and cured with biobased phenolic compounds. Analytical tests typically used in industry were performed on the cured coatings. They confirmed that this alternative crosslinking system gives a high level of performance with good adhesion properties and good impact resistance.