Controlled synthesis of ortho-substitution ortho-cresol novolac resins

The structure of ortho-cresol novolac resin is very important for the synthesis of ultra-high purity ortho-cresol novolac epoxy resin used as electronic encapsulating materials. But the relationship between the synthesis conditions and the structure of ortho-cresol novolac resin has not yet been completely clarified. This paper mainly studied the controlled synthesis of different proportion of ortho-substitution ortho-cresol novolac resins under different reaction conditions, such as molar ratio of ortho-cresol to formaldehyde, different catalyst types, reaction time. Then, the structure of different ortho-substitution ortho-cresol novolac resins were investigated by many measurements, such as FTIR, 1H-NMR, 13C-NMR, and the softening point. And the relationships between the structure and the reaction conditions were thus studied. The results indicated that, the ortho-cresol novolac resin with the needed proportion of ortho-substitution was synthesized through the adjustment of the reaction conditions.