Fast-Curing 3-Layer Particleboards with Lignosulfonate and pMDI Adhesives

Abstract

Currently, the industrial success of bio-based adhesives remains limited, despite the growing interest in these compounds. One example is the use of lignosulfonates (LS), a byproduct from the pulp and paper industry, which requires long pressing times to ensure proper performance for wood-based panel production. This study successfully manufactured particleboards using a low press factor of 7.5 s/mm, commonly used for conventional urea-formaldehyde resins on a lab scale. To the best of our knowledge, lignin-based particleboards have never been reported using such low press factors. Thus, 3-layer boards were manufactured in which the core layer was bonded with polymeric isocyanate (pMDI), and the surface layers were bonded with LS. Propylene carbonate (PC) was used as a solvent for pMDI to improve adhesive distribution. The optimum amounts of adhesive were determined using response surface methodology: 1.3% pMDI with 2.2% PC in the core layer and 15% LS in the surface layers. These boards obeyed the requirements of standard EN 312 for general-purpose boards for use in dry conditions (type P1). Their formaldehyde content, determined through the perforator method, was equal to that of the wood mix at the maximum value set by IKEA for class E0.5.