METHOD FOR PRODUCTION OF MODIFIED PHENOL-FORMALDEHYDE RESIN Russian patent published in 1997 - IPC

FIELD: production of modified phenol-formaldehyde resin which may be used as binder for production of glued woody articles. SUBSTANCE: at condensation of phenol, formaldehyde, sodium hydroxide and water during production of resol phenol-formaldehyde resin, phenol is partially substituted by ligno-containing compound, slime of cold settling is used as compound. Mixing of slime with water, sodium hydroxide and with phenol is carried out at 40-42 C. Into thus prepared mixture formaldehyde is added, its quantity is 90-92 % of total amount of formaldehyde and mixture is heated to 80-85 C. Thus obtained mixture is allowed to stand at this temperature within 40-45 min. The process is followed by heating up to boiling point, by boiling within 10 min and by cooling to 80-85 C. Then into thus treated mixture residual amount of formaldehyde is added and mixture is allowed to stand at 85-90 C till viscosity is 0.78-0.98 Pa/s. Mass ratio of phenol, formaldehyde, slime of cold settling and sodium hydroxide is 1:(0.9-1.1):(0.4-1.0: (0.3: 0.6) respectively. EFFECT: decreased content of free phenol and free formaldehyde in phenol-formaldehyde resin. 4 tbl