Phenol-Formaldehyde Novolac Resin Having Low Concentration of Free Phenol

摘要

A phenol-formaldehyde novolac resin having a low concentration of free phenol prepared by distilling residual phenol from a molten novolac resin and replacing at least a portion of the phenol with a solvent having a volatility equal to or less than phenol. Such modified novolac resins are suitable for the production of resin coated molding sands for shell molding and sand cores, as well as for the production of resin coated proppants for use in oil and gas recovery operations.