New wood adhesive products for construction.
Soy-based adhesives can be applied to green lumber and frozen lumber, enhancing the efficiency of the finger-jointing process. Finger-jointed studs are stronger and straighter than conventional lumber and will not warp.
PRF/Soy 2000, a soy-based wood adhesive developed with funding from the soybean checkoff, is used to bind scrap-shorts of lumber in a process known as finger jointing. Using the PRF/Soy 2000 in finger jointing reduces the amount of energy needed in curing.
As “going green” takes the construction industry by storm,
the inclusion of soy in more products is becoming increasingly prevalent - and
wood adhesives are no exception. The United Soybean Board (USB) and soybean
checkoff are committed to funding the research, development, and
commercialization of new industrial uses for soybeans. USB focuses efforts on
five target areas: adhesives, coatings and printing inks, lubricants, plastics,
“The soybean checkoff helps fund projects to increase soybean demand through
advancements in soy-based research and technology,” says Karen Fear, USB New
Uses vice chair and a soybean farmer from Montpelier, IN. “Adhesives are an
interesting market with a lot of potential.”
Oriented strand board is made of layered wood strands placed at right angles to develop maximum strength and stability. Checkoff-funded research has led to the use of soy protein in the adhesive to bind these wood strands.
A number of factors could lead to a future competitive
advantage for soy in the adhesives market. In 2004, the International Agency
for Cancer Research reclassified formaldehyde from a suspect carcinogen to a
known carcinogen. This began a flurry of technical work on
non-formaldehyde-containing resins to replace primarily urea formaldehyde (UF)
in non-structural wood-composite-panel glues. There are now five soy-based
glues for use in wood-composite panels. However, the future success of
soy-based adhesives may rest upon the cost of soymeal/flour,
petrochemical-based product pricing, technology development and
Soy meal and soy flour are only beginning to penetrate the wood-composite-glue
market. For the particleboard and medium-density-fiberboard markets, the
greatest interest is having a formaldehyde-free resin to resolve the issue of
formaldehyde emissions. This is needed to meet current and anticipated regulatory
demands and green initiatives, such as the Leadership in Energy and
Environmental Design (LEED) Green Building Rating System.
“Reducing formaldehyde emissions is one of the major factors in developing
soy-based adhesives,” says Fear. “Soy adhesives don’t have an odor or cause any
concerns with toxicity.”
Currently, soy-based formaldehyde-free glue systems are in use, representing
about 70% of the glue potential in this segment. If soy-based resins capture a
20% market share in the wood-composite-resin business within five years after
market introduction, the total soy meal and flour opportunity would be
approximately 744 million pounds, or 18.6 million bushels of soybeans.
Soy adhesives are becoming more common in many areas of the
construction industry as well. Structural panels refer to oriented strand board
(OSB) and softwood plywood. The current formaldehyde-free soy-based resins are
too high in viscosity for use in sprayable applications needed for making OSB. USB
supports research to develop the proper viscosity for this application at Oregon State
University, which was the
original inventor of soy-based formaldehyde-free glues used in interior
hardwood plywood. Developing soy-based glues that have a cost advantage will
also be a primary driver for change in the marketplace.
In the OSB and structural plywood markets, formaldehyde emissions are less of a
concern than reducing the cost of petrochemical resins such as phenol
formaldehyde and melamines, which are associated with the high costs of natural
gas and oil.
The most popular adhesive for particleboard has traditionally been urea
formaldehyde. However, since formaldehyde has been classified as a known
carcinogen, many mills are seeking to replace resins that emit formaldehyde.
This creates an opportunity for soy-based resins capable of replacing
Particleboard is a panel normally composed of discrete particles or pieces of
wood in contrast to fibers, combined with an adhesive resin or another binder.
The particles are bonded together under heat and pressure in a hot press and
formed into a board. The most popular adhesive used for particleboard is UF,
but there are soy-based resins capable of replacing UF. Costs to use soy-based
resins vary from mill to mill.
Medium-density fiberboard (MDF) is composed of uniformly small particles and is
of consistent density, ranging from 31 to 55 lbs./cu. ft. MDF is produced
through the use of heat and pressure in a hot press.
E2e Materials, Ithaca, NY, is developing a new soy protein and
renewable plant fibers composite particleboard and medium-density fiberboard.
The composites are described as a cost-competitive, formaldehyde-free solution
to traditional wood-composite particleboard and medium-density fiberboard. The
proprietary technology claims a high strength-to-weight ratio, which can result
in a 65% weight reduction without performance loss. Less material can equate
into less energy required to produce particleboard and MDF.
Current Soy-Based Resins
Current soy-based technology for use in wood-composite panels centers around
several different systems developed to produce lower cost and/or more
environmentally friendly systems. These include:
- Foamed glue extruded systems. This
system is used in laminating plywood veneers, where soy flour is substituted
for animal blood as a foaming agent for phenol formaldehyde resins.
- Formaldehyde-free adhesives. Soy meal or
flour are used in formaldehyde-free adhesives to minimize formaldehyde
emissions from wood-composite panels. In 2005, Columbia Forest Products
announced the first use of formaldehyde-free glue when it converted from the
use of urea-formaldehyde adhesives to a patented soy system. Other companies
have developed low-formaldehyde or formaldehyde-free glue systems with soy to
meet the challenges of regulatory and environmental issues.
Soy’s environmental benefits create a host of opportunities
for soy-based adhesives. The state of California
has announced two of the most stringent requirements for formaldehyde content
in composite wood panels.
Based on California’s intentions, Hercules
licensed soy-based formaldehyde-free technology from Oregon State
University that will be
used by Columbia Forest Products in its interior hardwood decorative paneling.
All of Columbia Forest Products’ mills have converted to this new soy-based resin,
which has resulted in new soy flour annual consumption. The Green Building
Council - specifically the LEED program - promotes formaldehyde-free panels as
being more environmentally friendly.
Many retailers are looking into soy-based products as well. Home Depot requires
its wood-composite panel suppliers to provide products that meet European 1
requirements for reduced levels of formaldehyde. IKEA has proposed that its
furniture have a maximum formaldehyde level of 0.07 ppm, which is lower than
the phase 1 requirement proposed by the California Air Resources Board (CARB).
Heat-resistant adhesives (HRA) present another opportunity for soy. The USDA
Forest Products Labs have done some preliminary work that indicates soy has
limited thermal softening under heat, which suggests that soy has good heat
resistance. The emerging market for this heat-resistant property would be
primarily in engineered-wood products such as finger joints, I-beams and
About the Soybean Checkoff
Like many commodities producers, soybean farmers
collectively invest a portion of their end-of-season profits to fund research
and promotion efforts. This collective investment is called a checkoff.
The soybean checkoff is supported entirely by soybean farmers with individual
contributions of 0.5% of the market price per bushel sold each season. The
efforts of the checkoff are directed by the United Soybean Board, composed of
68 volunteer farmer-leaders nominated by their state-level checkoff organizations,
called Qualified State Soybean Boards (QSSBs). The nominees are appointed by
the U.S. Secretary of Agriculture.
For more information, visit www.unitedsoybean.org.