Improved water resistance of UF adhesives for plywood by small pMDI additions
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Addition of small amounts of isocyanate (pMDI), between 10% and 15% by weight, to UF resins for plywood considerably improve the UF glue line water resistance. Analysis of the plywood by X-ray microdensitometry indicate that on both sides of the glue lines there is a local density increase which reflects either some adhesive diffusion in the wood layers immediately in contact with the glue line, or some extent of wood densification as a result of the gluing process, or both.
KeywordsIsocyanate Glue Line Plywood Panel Hybrid Resin Wood Layer
- 1.Adcock T, Wolcott MP, Peyer SM (1999) Urea formaldehyde/diphenylmethane diisocyanate copolymer adhesives: possible use as an adhesive system for straw based particleboard. In: Proceedings of the third European panel products symposium, Llandudno, UK, pp 67–76Google Scholar
- 2.Despres A, Pizzi A, Delmotte L (2005) 13C NMR investigation of the reaction in water of UF resins with blocked emulsifiable isocyanates. J Appl Polym Sci (in press)Google Scholar
- 4.Pizzi A, Walton T (1992) Non-emulsifiable, water-based diisocyanate adhesives for exterior plywood – Part 1: novel reaction mechanisms and their chemical evidence. Holzforschung 46(6):541–547Google Scholar
- 5.Shadurka V, Binder WG, Dunky M, Kantner W (2003) Blocked isocyanates in UF resins: reaction pathways and cross-linking. In: Proceedings of the 7th panel products symposium, Llandudno, Wales, UK, October 2003, pp 57–69Google Scholar