Wood glue that doesn't use formaldehyde

Columbia Forest Products learned about natural adhesives from the blue mussel. This ocean species attaches itself firmly to underwater structures without use of toxic chemicals through unique amino acids (specifically, DOPA) found in their marine adhesive proteins (MAP).   Modeling these MAPs researcher, Dr. Kaichang Li, was able to modify soy proteins. When adding catechol groups to soy protein the structure becomes remarkably similar to marine proteins, creating much stronger and more durable adhesion properties. Using soy protein modification as a foundation, Li went on to create a product that would be more realistic for large quantity production.   During manufacturing, wood fibers are infused with soy proteins. Kymene resin is then applied. Kymene is a curing agent which works to block amino acids in soy that are not found in marine proteins, thus creating a structure that more closely resembled MAPs with their strong adhesion properties. When heated, this resin cross-links with the soy proteins in the wood fiber to create a strong bond. This bond proves to be water resistant and mimics closely the process used by blue mussels to adhere to underwater objects.   

Key Differentiators

Purebond® differs from other wood adhesives in that it is completely free of formaldehyde. In addition to being recognized by the World Health Organization as a possible carcinogen, formaldehyde is also a skin, eye, and orifice irritant. Concerns of its toxicity have arisen for manufacturer workers and consumers alike. Purebond® has found a way to elliminate these concerns by mimicking the way that blue mussels adhere themselves to objects (e.g., rocks) in the ocean.

Biomimicry Story

Dr. Kaichang Li is a chemist who has always had a curiosity about nontoxic composites. Being an associate professor in the Department of Wood Science & Engineering at Oregon State University in Corvallis, Oregon, Dr. Li was very close to the marine life living along the coast. When harvesting blue mussels during a low tide collection, Dr. Li became intrigued by how strongly these mussels attached themselves to rocks along the shore; he had never witnessed such strong attractive forces in water. His curiosity launched him into innovative research, exploring the possibilities of applying such strong adhesion properties elsewhere. Many scientists have explored the strong bonding properties of the catechol groups in certain proteins, but Li was the first to consider their usefulness in wood science. His research led him to successfully demonstrate the potential of MAPs as wood adhesive elements.     Due to the expensive nature of isolating these mussel proteins, Li sought funding to continue his research for a more plausible design that would support large-scale manufacturing. Finally, Li discovered a way to manipulate soy proteins (which are abundant and cheap) in such a way that they closely resembled the marine proteins and their water-resistant and adhesion properties. He patented this process and soon after Columbia Forest Products switched all seven of their plywood plants to the Purebond® manufacturing process. It was the first company to release completely free formaldehyde products. In doing so, it replaced the use of an estimated 47 million pounds of conventional UF and PF resins and reduced emissions of hazardous air pollutants at each of its plants by 50-90%. (Source: Biomimicry Case Study 2011).

Challenges Solved

Columbia's Purebond® is a soy-based formaldehyde-free technology used in the construction of hardwood plywood products whose strength is comparable to the market's latest competitors. Eliminating formaldehyde from its manufacturing process makes this an attractive product because of the health concerns that are raised during formaldehyde production. Soy proteins were used previously in hardwood products, but their weak strength led them to be outcompeted by other (formaldehyde-based) products whose design proved more durable. Purebond® has alleviated this strength problem through a treatment process that actually alters the chemistry of the soy-proteins to more closely resemble the chemical structure of marine proteins, which are known for their immense strength and adhesion properties. In addition, soy-proteins are abundant and relatively inexpensive, meaning the Kymene resin is readily producible. Now there is a toxin-free adhesion product whose strength is comparable to market competitors.