Investigation of soy protein‐kymene® adhesive systems for wood composites

Abstract This study investigated a new adhesive system, consisting of soy protein isolate (SPI) and Kymene ® 557H (simply called Kymene) (a commercial wet‐strength agent for paper), that was prepared by mixing SPI and Kymene. Wood composites bonded with SPI‐Kymene adhesive preparations had shear strengths comparable to or higher than those bonded with commercial phenol formaldehyde resins. Wood composites bonded with the new adhesive system had high water resistance and retained relatively high strength even after they had undergone a boiling‐water test. The new adhesive system is formaldehyde‐free, easy to use, and environmentally friendly. Kymene was proposed to serve as a curing agent in SPI‐Kymene adhesives.