Adhesive qualities of soybean protein-based foamed plywood glues

The potential of soy protein-based plywood glues for foam extrusion was evaluated. Standard glue mixes containing the soy flours Honeysoy 90, ISU-CCUR, Nutrisoy 7B, and defatted Soyafluff, and the soy concentrates Arcon F and Procon 2000 showed excellent foaming and adhesive qualities but did not have the ability to refoam. To improve refoaming capability, the formulations were modified by increasing the quantities of soy flour or concentrate so that they provided 3.48 g protein/100 g of glue mix. This was the amount of protein contributed by animal blood when it was used as the extender in the standard formulation for foamed glue. All the modified glues containing soy flour or concentrate had good refoaming properties and adhesive strengths that were at least equal to that of the control glue. Simple cost analysis also indicated that when soy flour was used, the modified formulations were cheaper to produce than the current blood-based glue.