Tofu ingredient yields formaldehyde-free glue for plywood

Madison, WI – In a real-life “back to the future” story, scientists today reported that the sustainable, environmentally friendly process that gave birth to plywood a century ago is re-emerging as a “green” alternative to wood adhesives made from petroleum. Speaking at a meeting of the American Chemical Society, they described development of new soy-based glues that use a substance in soy milk and tofu and could mean a new generation of more eco-friendly furniture, cabinets, flooring, and other wood products.

“Protein adhesives allowed the development of composite wood products such as plywood in the early 20th century,” said Charles Frihart, PhD, who participated in the research project. “Petrochemical-based adhesives replaced proteins in most applications based upon cost, production efficiencies, and better durability. However, several technologies and environmental factors have led to a resurgence of protein, especially soy flour, as an important adhesive for interior plywood and wood flooring.”

The new adhesive contains soy flour and an additive used to make paper towels resist water. It performs as well as conventional wood adhesives for interior products, the scientists said, and does not produce the harmful formaldehyde vapours released from traditional plywood, particleboard, and other composite products. Certain petroleum-based adhesives can release formaldehyde, a potential human carcinogen, or substance capable of causing cancer. The scientists identified a highly promising soy-based glue composed of soy flour, a special water-resistant additive, and other modifiers. Together these ingredients form a polymer glue for interior wood products that performs as well as the existing petroleum adhesives but does not contain formaldehyde, they said.