Wettability of Kraft Paper with Biobased Impregnation Resins for the Production of High-Pressure Laminates.

High-pressure laminate (HPL) manufacturers are increasingly looking for more environmentally friendly solutions for their production processes to reduce their environmental footprint. Replacing conventional phenol-formaldehyde resins (PF) with sustainable alternatives from renewable resources still remains a challenge to address. The suitability and wetting behavior of an impregnation resin are strongly dependent on its compatibility with the paper used. Thus, kraft papers with varying recycled fiber content were analyzed regarding their chemical composition, structural morphology, and wettability. Recycled paper exhibited a lower surface free energy and increased two-sidedness compared to paper made from virgin fibers, which was attributed to a higher lignin and extractives content as well as alterations in the fiber morphology due to the recycling process. Additionally, biobased resins derived from carbohydrates and their derivatives were synthesized and evaluated for their wetting behavior. Contact angle measurements and impregnation trials demonstrated distinct differences in penetration behavior between commercial PF resins and biobased alternatives. Despite these differences, the biobased resins exhibited comparable overall wettability, though with different penetration dynamics, highlighting their potential for sustainable HPL production.