Abstract: For producing chip or fiber boards or like articles by bonding particulate lignocellulosic material like chips or fibers with tannin-based adhesives like tannin resins or tannin containing resins, the lignocellulosic material is pre-hydrolyzed by means of adding acids, acidic salts or other acid liberating chemical compounds prior to adding a particular composition of adhesive material.

Abstract: A low cost method of binding lignocellulosic materials utilizing ammonium based spent sulfite liquor alone as the binder. Hot pressing a mat comprising lignocellulosic material and ammonium spent sulfite liquor at a temperature above 170.degree. C. decomposes the spent sulfite liquor. The decomposition products subsequently condense and polymerize in the presence of lignocellulosic materials to produce a composite product. An exterior grade board can be produced under certain operating conditions. Utilizing the lower molecular weight fraction of the liquor provides a more efficient binder.

Abstract: A method of making a thermosetting binder for lignocellulosic materials, utilizing spent sulfite liquor, and a method of making a particleboard product. Spent sulfite liquor treated with sufficient sulfuric acid to provide a lignosulfonic acid content of not less than 0.8 milliequivalent weight of NaOH per gram of spent sulfite liquor solids, makes it possible to make particleboard with press time and physical properties comparable to phenol or urea formaldehyde bonded boards but at considerably reduced material cost.