ADHESIVE FOR THE MANUFACTURE OF PLYWOOD, PARTICLE, FIBRE BOARDS AND SIMILAR PRODUCTS

1404536 Phenolic resin adhesives; particle board KESKUSLABORATORIO-CENTRALLABORATORIUM AB OY 13 Sept 1973 [14 Sept 1973] 43005/73 Headings C3R and C3N [Also in Division B5] An aqueous adhesive for use in the manufacture of plywood, particle boards and fibre boards comprises phenolformaldehyde resin and lignosulfonates at least 55% wt. of which lignosulfonates have a molecular weight greater than 5000. The lignosulfonates are generally in the form of their alkali metal or alkaline earth metal salts containing an excess of alkali metal or alkaline earth metal hydroxide such that a 10% wt. aqueous solution has a pH of 6-13. A 50% wt. aqueous solution of the lignosulfonates generally has a Brookfield viscosity greater than 10,000 cP. at 23‹ C. Optional ingredients include an aldehyde hardener such as formaldehyde, paraformaldehyde or furfuraldehyde; extenders such as chalk, wood flour and wheat flour; and paraffin. In Examples 5 and 6 particle boards are made from birch log chippings by spraying them with an aqueous adhesive comprising phenolformaldehyde resin, macromolecular, sodium lignosulonate, sodium hydroxide, paraformaldehyde and additionally in Example 5 paraffin.