Beyond formaldehyde
The battle over urea-formaldehyde [UF] resin appears to be ending. UF resin had been a popular resin with wood panel producers for years-cheap, easy to use, and quick to cure.
But because these panels were generally used for interior applications, it meant that formaldehyde was being released into indoor air. UF received its “death sentence” in the mid 2000s, as a result of two separate actions: the USGBC LEED program awarded a point to projects using panels made without UF Resins, (EQ 4.4), and the California Air Resources Board (CARB) legislated a program of reducing formaldehyde emissions to extremely low levels-levels that UF resins are unlikely to achieve. So, if UF resins are the past, what’s the future? Some possibilities:
1. Melamine urea formaldehyde: the addition of melamine to UF resin results in improved moisture resistance and reduced emissions, however, it still contains UF as a component, and likely is already on the DOA list.
2. Phenol formaldehyde: UF’s distant cousin, is the current “go to” resin for producers but is expensive, takes a look time to cure, darkens the board [due to longer curing time], and can result in “resin” spots appearing on the surface. PF does emit formaldehyde at very low concentrations so its days may be numbered.
3. pMDI [polymeric methylene diphenyl diisocyanate] resin forms both a chemical and a physical bond, making the bonds far stronger than either UF or PF bonds, and is completely inert when cured, and has a high degree of moisture resistance. But it is very expensive, and uses carcinogenic compounds in its manufacturing.
At this point, a truly “green” resin for wood panels that is also commercially viable is the Holy Grail of research. A lot of resin research has been done using soy compounds and mollusks as a potential raw material. One wonders if the future of a truly “green” resin may yet lie in its past. Courtesy of Brian McLeod www.panelsource.net.
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