Auburn Study Shows Soy Adhesives Reduce Carcinogens, Boost Cost Savings
Research at Auburn University, funded by the United Soybean Board and recently published in the International Journal of Adhesion and Adhesives, shows several benefits of using soy flour, derived from soy meal, to create wood adhesive. The new study finds that soy-based wood adhesives are not only environmentally friendly due to no formaldehyde emissions but also come with attractive cost savings.
In this study, Auburn researchers focused on particle board, oriented strand board (OSB) and medium density fiberboard (MDF) applications. These types of boards are used in home construction and made by bonding pieces of wood with adhesive to maximize strength and stability.
Formaldehyde-based adhesives are being phased out in favor of methylene diphenyl diisocyanate (MDI) and phenol formaldehyde pairing with soy flour due to cost savings. The study showed that up to about 20% of MDI used in OSB can be replaced by soy flour without compromising board properties. Other key benefits are little or no new equipment is required to replace MDI with soy flour, and the soy flour bonds with MDI and wood, creating a safe but sturdy bond.
USB farmer-leader and Alabama soybean farmer Annie Dee was involved in this cutting-edge project. “North American OSB production is about 20 million cubic meters. These products are used indoors, where the moisture sensitivity of soy would not be an issue, and a higher level of soy flour substitution could be applied,” says Dee. “There are also green benefits that accrue from the use of soy flour because MDI is hydrocarbon based.”
“According to the study, although soy flour augments the properties of MDI to a small extent, its major benefit is cost savings,” adds Dee. “Soy flour is about three times cheaper than MDI, so there is a significant cost savings for using soy in as high of a percentage as possible.”
Environmental and sustainability benefits also go hand-in-hand with soy flour, in addition to added marketing potential. “Based on their purchases, consumers are demanding greener products to help protect the environment now and for future generations,” says Dee.
U.S. soybean acres came in at nearly 90 million in 2018, putting soybean production at an all-time high, and making consistent supply a near guarantee for manufacturers using the ingredient in product formulations.
This study not only creates opportunity for both improved performance and economics for the wood products industry, but also could have much broader implications for the future. OSB competes with plywood, one of the most commonly used construction products today, and these results indicate OSB and plywood could be interchangeable. OSB has already seen significant growth due to its lower price and competitive performance.
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 Hand, W. G., Ashurst, W. R., Via, B., & Bangerjee S. (2018). Curing behavior of soy flour with phenol-formaldehyde and isocyanate resins. International Journal of Adhesion and Adhesives, vol. 87, pp. 105-108.