Quick-curing phenolic resin and process for preparing same

摘要

Disclosed herein is a novel high-ortho phenolic novolac resin having excellent quick-curing property and thermal stability for use as phenolic resin molding material and perfectly free of divalent metal salt which is detrimental to the electrical properties of the molding material. This resin can be obtained by condensing a phenol and an aldehyde in an aldehyde/phenol molar ratio ranging from 0.6 to 1.0 and at a reaction temperature of more than 100 DEG C. at which the selectivity for condensation at the para-position is lowered (that is, the probability of the condensation at the ortho-position increases), with a weakly acidic catalyst having a specified dissociation constant (pKa value). The high-ortho phenolic novolac resin (having the specific molecular weight and ortho/para linkage ratio) obtained from said reaction is very useful for industrial applications as a phenolic injection molding material or epoxy/phenolic low-pressure encapsulation molding material with excellent electrical properties.