Kaichang Li was wading in the waters off the Oregon coast when he
noticed a group of mussels gripping to a rock beneath the surface of the
Observing the mussels’ unfaltering hold on the rock, despite crashing
waves all around, Li, an assistant professor in Oregon State University’s
College of Forestry, set out to determine how they hang on so
Five years later, and having figured out that mussels get their super
grip by secreting proteins known as byssal threads, Li and his colleagues
are on the forefront of the woodworking industry’s latest adhesive
alternative, which Li says would work especially well in plywood
For the adhesive to work as imagined, it would have to mimic the
properties of the byssal threads. Li learned that the mussels’ threads are
effective because they are strong, yet flexible, enough to absorb the
energy caused by constant movement of the waves.
Li had to find a protein that had a similar effect, and he found it in
This main ingredient has been lauded by many in the industry because it
is formaldehyde-free, giving companies another adhesive option.
Formaldehyde remains under fire due to its widely debated health effects
and its listing last year as a “known” carcinogen, given by the
International Agency for Research on Cancer.
One of the companies in support of the soy protein-based adhesive is
hardwood plywood manufacturer Columbia Forest Products, based in Portland,
The company gained exclusive sub-licensing rights from Hercules Inc., a
partner in development and which now has the licensing rights on the
adhesive and its proprietary curing agent. Columbia soon will finalize a
complete changeover of its three North American veneer-core and
Woodstalk-core hardwood plywood manufacturing facilities to use the
soy-based adhesive in place of urea formaldehyde resins. Columbia says the
panels it produces with the adhesive are compliant with and earn one point
toward the U.S. Green Building Council’s LEED-EQ Credit 4.4 for
Low-Emitting Materials: Composite Wood.
The adhesive is quite easy – and relatively cheap – to make, Li says.
So easy, in fact, that The Oregonian newspaper reported Li can whip up a
batch with soy flour and a kitchen mixer. The newspaper also reported that
Li’s phone has been ringing non-stop with interested consumers and
manufacturing companies since the adhesive was unveiled.
Due to patent constraints on the adhesive, Li could not speak in-depth
about its composition. He did, however, respond to a series of questions
Wood & Wood Products posed to him.
Kaichang Li: I discovered the mussel
phenomenon in 2000, and it was pure scientific research from there. I was
curious why and how a mussel could stick to rock or a piece of wood so
strongly in water. Then [my colleagues and I] began to
Basically, the mussels secrete a protein that is pretty unique. We
mimicked the protein to investigate why and how the protein is so strong
and water resistant. We graphed the key function of the mussel protein to
a soy protein.
When you look at the chemistry of the adhesive, there are no volatile
organic compounds released. In the soybean flour, all the oil is already
extracted, so there is nothing that could be harmful. There is no
ingredient in this that would be volatile.
Li: Soy bean flour was used as a wood
adhesive since 1930 and into 1960. It was a commercial production at that
time. So, soy protein – soy flour itself – is a good wood adhesive.
Unfortunately, soy protein is not as strong or water-resistant as a
synthetic resin. We needed to modify the soy protein itself and use our
unique curing agent and some other ingredients to make it water resistant.
In the beginning, it was just all the chemical modifications.
Basically, you can think of it this way: take soy flour, dissolve it in
water, penetrate it into wood, then crosslink it. If you have something to
cross soy flour – so the flour becomes like a 3-D network – it becomes
water-insoluble. It's basically like putting a key in a lock and making a
turn: You can’t pull it out then. So the soy flour, when it gets into wood
and you hot press it, it cures and you have the 3-D, water-insoluble
Li: For exterior-use wood composites,
it is a standard to run a four-hour, two-cycle boil test. Basically, you
take a wood composite, and boil it in water for four hours. Then you dry
it and boil it again. If it doesn’t eliminate, then it’s really water
On one occasion, we boiled the wood composite one day, then let it soak
in the water. The next day, we came back and turned on the heater and went
through the test one more time.
That isn’t the standard method to run the test, letting it soak. We
were just curious [to see the results of soaking it]. It was still
resistant to the water after the test.
[Other types of adhesives that went through the battery of tests
reportedly would result in spongy material, while the soy adhesive would
hold its tight grip.]
Li: One other adhesive has been
licensed by Hercules. Hercules is the company that produces the curing
agent. Hercules bought the license from Oregon State University. Hercules
is not a forest product company. They will sell it to whoever wants to use
it. For that patent, it is out of my hands. They still want me to do
research and development work and determine if it can be used in different
Basically, it’s their stuff now. Columbia Forest Products also
contributed research dollars, so I think they have some benefit there,
too. Columbia told me they use it continuously now. At each mill, they
have several production lines. I don’t know exactly how many of them are
using it, but [I know] at least two mills are using it
Li: Well, I’ll phrase it this way:
This adhesive is cost competitive to UF, urea formaldehyde. I can’t tell
you any price or numbers, but I think Columbia is happy about it, and they
are satisfied with the prices.
Li: I get a lot of phone calls and
people write e-mails. Actually, someone wrote me a letter.
Li: Since we were successful with the
hardwood plywood [application], we are going to [attempt to] make
[adhesives for] particleboard, MDF and OSB. A number of companies in
Oregon are really interested in exterior-use plywood, exterior-use
products, laminating lumber and that kind of stuff. We still have a lot of
work to do.
Each mill is unique and may want me to formulate an adhesive slightly
different to meet their facility, so I'll be busy for the next couple of
One of the driving forces here is the petroleum oil. The oil price is going up and will probably remain high in the near future. With all these petro-chemical-based wood adhesives, like phenyl formaldehyde or urea formaldehyde, the price of them may remain high. Our adhesive is from a renewable resource – it should have some long-term benefit for sustainable growth.
|© 2006 Vance Publishing, Inc.|