Investigation of lignin used in preparing plywood adhesive

Phenol was partial replaced by lignin to prepare lignin-phenol-formaldehyde(LPF) adhesive,which was extracted from the black liquor with sulfate acid,nitrate acid and hydrochloride acid.The properties of above adhesives were determined,such as solid content,dynamic viscosity(40 ℃),free formaldehyde content and glue strength.The effects of lignin content,catalytic content and the ratio of phenol to formaldehyde on LPF resin properties were studied.As a result,the properties of adhesives were all good when the adding amount of above three lignins was 20% by weight.Tacking LPF adhesive containing 20% nitrate lignin as a example,obtained adhesives showed promising results when the catalytic content was 0.6% and the ratio of phenol to formaldehyde was 1∶1.5.Using lignin replaced partial phenol not only the production costs were decreased,but also that was favorable for environment.