Hybrid Wood Bond: Studies of the interactions between UF/pMDI hybrid adhesives and the final properties for the production of low formaldehyde emission wood based panels

Combined mixtures of polymeric diphenylmethane diisocyanates with urea formaldehyde resins can provide alternative adhesives with improved properties. Although such adhesives are reportedly industrially used in some cases.

Fiche signalétique

  • Département HESB | Architecture, bois et génie civil
  • Pôle de recherche Matériaux et la technologie du bois
  • Champ de recherche Technologie des adhésifs et chimie des polymères
  • Organisme de financement COST
  • Durée 01.09.2005 - 31.03.2007
  • Responsable du projet Frédéric Pichelin
  • Direction du projet Stefanie Wieland
  • Mots-clés urea formaldehyde, isocyanate, bonding, formaldehyde emission, laser scanning microscopy

Contexte initial

The first phase of the project does mainly concern the analyses of the colloidal appearence of UF/pMDI glue mixes by means of different microscopic methods. The second phase is focused on the investigation of the panel production related properties concentrating on the influence of the hybrids on the formation of the vertical density profile of the panels.


The aim of the project is an investigation of the correlation of the colloidal appearance of such selected hybrids with the gluing, pressing and final panel properties.

Compétences clés

Formulation of wood adhesives, material testing, wood based panels, hybrid adhesives


The panel properties as well as the formaldehyde emissions were evaluated. Best results concerning the improvement of the panel properties were obtained for glue-mixes with low molar ratio UF 0,75:1 and emulsifiable pMDI. Starting from a ratio UF/pMDI of 70/30 all qualitative requirements of the international standards could be passed. However, lower Formaldehyde emissions, satisfying the requirements of F** (E1), were only reached using glue-mixes with lower molar ratio UF.


The development of the project increased the knowledge in the field of the UF/pMDI hybrid adhesives. Further investigations are of interest in order understand and improve the physical properties of wood based panels using hybrid adhesives.