The invention relates to the field of refining and application of wood
fiber biomass, and discloses a
lignin-based
formaldehyde-free
adhesive, a
lignin-based plywood and a preparation method and application of the
lignin-based
formaldehyde-free
adhesive and the lignin-based plywood. The lignin-based
formaldehyde-free
adhesive disclosed by the invention comprises the following components: L-
cysteine lignin, and the
solid content of the lignin-based formaldehyde-free adhesive is 10-45wt%. The method comprises the following steps: mixing an
aqueous solution of L-
cysteine hydrochloride and
lactic acid with raw materials for pretreatment; performing extraction and vacuum
filtration on the obtained suspension to obtain dissolved lignin and
hemicellulose filtrate, and performing extraction and purification on the filtrate to obtain L-
cysteine lignin; the lignin-based formaldehyde-free adhesive is prepared by uniformly dispersing the L-cysteine lignin in water. According to the invention, the used
solvent is green and nontoxic in source, the hydrated lignin-based adhesive with good fluidity is prepared with low
solid content, and the prepared plywood shows excellent dry and
wet bonding strength,
solvent resistance and
weather resistance, and meets the preparation requirements of national I-class plywood.