Gluten Protein Adhesives for Wood Panels

Adhesives for wood particleboards based on hydroxymethylated or glyoxalated hydrolysed gluten protein with addition of an equal proportion of tannin/hexamine resin or without any addition of synthetic resins are shown to yield results satisfying the relevant standard specifications for interior wood boards. Even better are resins based on hydroxymethylated or glyoxalated hydrolysed gluten protein to which has been added a small proportion of an isocyanate (pMDI). Adhesive resins formulations based on the latter in which the total content of natural material was either 70% or 80% of the total resin solids content gave good results. Resins based on the former in which the natural material content was approximately 90-95% also gave good results. The 30/70 pMDI/hydroxymethylated lignin adhesive formulation was tried at progressively shorter pressing times yielding internal bond strength results acceptable for relevant interior grade standards at industrially significant pressing times. (C) Koninklijke Brill NV, Leiden, 2010