Foaming Soy Adhesives May Help Soybeans Bond With Lumber Industry

A new soy-based glue may give plywood manufacturers what every industry wants: faster production at a lower cost. Agricultural Research Service (ARS) scientists in Peoria, Ill., substituted soy flour for an expensive animal blood protein now used in plywood glue formulas.

Concerns about animal blood’s limited supply and about health issues prompted the search for alternative protein extenders. Extenders are substances added to an adhesive to reduce the amount of resin required. The plywood glues were designed to be applied with foam extrusion, one of four conventional ways the industry applies glue to wood.

Soy flour--at 22 cents per pound--made the best foaming glue. That glue was 50 cents per 100 kilograms cheaper than conventional formulations. Soy flour makes up 3.5 to 5.5 percent of the glue mix, with the adhesive resin being the primary component. Soy flour has less protein than animal blood, so it can’t be used one-for-one in place of blood protein in the glue. But by adding more soy flour, the researchers produced a glue that foamed better at less cost.

Other benefits of the soy-based glue are that it requires less drying time, uses less water, and produces less waste than conventional plywood glues. The United Soybean Board provided funding for this project.

ARS is the chief scientific research agency for the U.S. Department of Agriculture.

A report on the soy glue appears in the January issue of Agricultural Research magazine.

Scientific contact: Milagros P. Hojilla-Evangelista, ARS National Center for Agricultural Utilization Research, Peoria, Ill., phone (309) 681-6350, hojillmp@mail.ncaur.usda.gov.