A plywood glue comprises an aqueous mixture of from 30-90 parts by weight urea formaldehyde resin, from 10-70 parts waste liquor from the acid sulfite pulping of lignocellulose, an amylaceous filler and from 0-2 to 4.0% ammonium ion (expressed as NH.sub.3), based on the waste liquor solids. Prior to mixing, the sulfite waste liquor component of the mixture has a pH of from 3-9; the urea formaldehyde resin, a pH of from 6- 9. The urea formaldehyde resin is further characterized by a molar ratio of formaldehyde to urea of from 1.2 to 2.5 and a methylol content corresponding to a Witte number of from 1.0 to 2.2.PP Plywood is made using the herein described glue by applying to the surfaces of wood veneers a bonding quantity of the glue, assembling the adhesive-coated veneers, and pressing the resulting assembly to cure the glue and bond the veneers together.
展开▼
