Use of soy proteins in polyketone-based wood adhesives

This paper describes the preparation of aqueous emulsions consisting of soy proteins and chemically modified thermosetting aliphatic polyketones. Emulsions were prepared in a range of total solids contents and different addition protocols were tested. Room temperature stability and structure of the prepared emulsions were studied as a function of time using dynamic light scattering, rheology, cryo-scanning electron microscopy (Cryo-SEM) and confocal fluorescence microscopy. Emulsions at 40–45 wt% total solids content with an average particle size less than 1 μm, and a viscosity less than 1 Pa s could be prepared and were shown to be stable for more than 6 months.Emulsions with protein contents up to 40 wt% with respect to the unmodified polyketone fulfill wood adhesive requirements according to the European Standard EN-314. Confocal fluorescence pictures clearly demonstrate a better penetration of the protein/polyketone adhesive into the wood surface as compared to the one of the adhesive based on polyketones only.