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

FIELD: production of composite materials. SUBSTANCE: desired resin is prepared by condensation of phenol with formaldehyde, the process is carried out in the presence of oxalic acid at boiling point of reaction mixture. Then resin supernatant water is removed by evaporation at temperature being increased from 100 C to 130 C by mixing, Reynolds criteria being 1500-1900. The process is followed by vacuum evaporation at (4-20) 10_-3 MPa and by distillation of residual phenol. Said distillation takes place at temperature being increased up to the end of vacuum distillation, the process is carried out by mixing at Reynolds criteria 5000-8000. Thus obtained resins contain free phenol, its quantity being 0.32-0.5 %. EFFECT: improves impregnation and wetting ability of desired resins. 1 tbl