Citric‐Acid Polyester‐Modified Melamine–Formaldehyde Resins: Mechanistic Insights and Implications for Greener Decorative Laminates

ABSTRACT

Growing sustainability demands are driving the development of renewable polymer systems for coating applications. Polyester resins, produced by polycondensation of polyols and acids, represent a versatile class of materials. Among them, poly(glycerol citrate) (PGCit), synthesized from abundant and low‐cost citric acid, has emerged as a promising bio‐based alternative. For the laminate industry, which remains strongly dependent on fossil‐based resins, PGCit offers clear sustainability benefits. However, high viscosity and limited surface durability constrain its use in industrial laminate manufacturing. To address this limitation, this work investigated PGCit‐modified melamine‐formaldehyde (MF) resins for the impregnation and lamination of decor paper. Thermal analysis and chemo‐rheology indicate that PGCit modification accelerates curing, consistent with residual acidity and possible co‐reaction within the blends, allowing lamination at reduced cure temperatures, as compared to conventional MF, with slightly extended press times. Unlike other bio‐based impregnation systems, PGCit‐blended MF resins produced visually transparent surfaces and substantially increased the bio‐based fraction of the MF polymer (up to 50%). Although industrial tests for chemical resistance and porosity remained slightly below threshold values, this underscores the need for formulation optimization. However, PGCit‐modification represents a promising approach for reducing cure temperatures and supporting the transition of the laminate industry towards more sustainable practices.