In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source

it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine (G-MMU-M). A series of G-MMU-M resins with various formulations of raw materials were successfully prepared. The basic properties and bonding performance of the G-MMU-M resins were determined. Furthermore

the structures of resins were characterized by FTIR

13

C NMR

XPS

and ESI-MS. The results show that the prepared G-MMU-M resin remains stable for 30 d

meanwhile

the dry and wet bonding strength of the plywoods bonded with the resins

solid content and viscosity are influenced greatly by the addition amount of melamine and MMU/G molar ratio. The G-MMU-M resins with MMU/G molar ratio of 0.9:1.0 and 8% melamine exhibit the highest dry and bonding strength of 1.98 MPa and 1.27 MPa

increased by 34% and 63%

respectively

in comparison with glyoxal-monomethylolurea (G-MMU) resin. In the G-MMU-M resins

there were four main oligomers including M—CH(—

+

CH-MMU)-O-MMU

M-CH(—CH

2

OH)-MMU-O-MMU

M—CH(—OH)—

+

CH-MMU-O-MMU

and M—CH(—

+

CH-MMU)-MMU-p-G.