Tannin adhesive has been used as a thermosetting wood adhesive
for wood panels to reduce formaldehyde emission (Kim and
Kim, 2004). Tannin adhesive gives excellent adhesive performance,
good moisture resistance, and tends to give a lower formaldehyde
emission than UF resin (Kim et al., 2007b). Before surface coating,
formaldehyde emissions from the products glued with tannin
adhesive was already less than E1 grade (under 1.5 mg/L) of formaldehyde
emission level in the Korean Standard even though paraformaldehyde
was contained in tannin adhesive, as shown in Table
2. The tannin/PVAc hybred adhesives samples were showed similar
tendency with the natural tannin adhesive. PVAc was not caused
increasing formaldehyde emission.
When fancy veneer on plywood was coasted by UV curable urethane
acrylate coating, the formaldehyde emission from this flooring
was reduced about two thirds. In the tannin/PVAc hybrid
adhesives system, the role of PVAc was not make formaldehyde