METHOD OF PREPARING RESOL-TYPE PHENOL-FORMALDEHYDE RESIN Russian patent published in 2000 - IPC

FIELD: gluing of plywood and other materials prepared by hot compression method. SUBSTANCE: described is method of preparing resol-type phenol-formaldehyde resin by condensation of diphenylolpropane with formaldehyde in the presence of sodium hydroxide during heating operation. Process is carried out in the presence of borax at diphenylol propane to formaldehyde to sodium hydroxide molar ratio of 1:4.5-5.5:0.9-1.1, respectively. Diphenylolpropane is first condensed with formaldehyde at molar ratio thereof from 1: 4.5-5.5 in the presence of 3.0-6.0 wt parts of borax per 100 wt parts of diphenylolpropane at 50-55 C for 28-30 minutes, and sodium-hydroxide is then added in amount of 0.6-0.7 mole per 1 mole of diphenylolpropane, and condensation is carried out for 60-90 minutes, temperature is raised to 94-100 C, the whole is maintained for 5-20 minutes, reaction mixture is cooled to 65-70 C, 0.3-0.4 mole is added per 1 mole of diphenylolpropane and sodium hydroxide, and condensation is carried out for 5-15 minutes and temperature is then raised to 80-87 C and reaction mixture is maintained at the above-mentioned temperature for 5-60 minutes. EFFECT: lower toxicity of resin and glued products based thereon, greater adhesion of resin to wood and improved environment conditions. 3 ex, 1 tbl