Using Soybeans to Replace Synthetic Adhesives for Wood Bonding
Concerns about formaldehyde emissions from synthetic urea-formaldehyde adhesives have led to an interest in no-added-formaldehyde adhesives, especially those made from biobased materials. Natural protein adhesives have been used as wood adhesives back to the beginning of recorded history. Although instrumental for developing wood products prior to World War II, they were replaced by the easier to use, higher performing, and lower cost synthetic adhesives. The resurgence of soybean-based adhesives has been driven by new no-added-formaldehyde technology and the wide availability and low cost of soybeans. The main market so far has been for decorative plywood and engineered wood flooring; however, improved products are needed for a bigger market share in plywood and for use in particleboard. Soybeans are widely grown in the United States to replenish the soil and provide oil for healthy food applications as well as for biofuels and polyurethanes. The soy meal remaining after oil extraction is widely used as animal feed. While Forest Service cooperator Solenis is doing applied research at the agency’s Forest Products Laboratory in Madison, Wisc., under a cooperative research and development agreement, the laboratory is furthering the understanding of the fundamental nature of proteins in soy flour. Forest Service scientists have determined that prior literature has many misconceptions about protein structure. Collaboration among an adhesive chemist, a physical chemist, and two protein chemists, along with input from soy producers, has led to a better understanding of what is controlling soy adhesive performance. This improved understanding helps Solenis and others make better quality, more cost-effective wood products.