Method of producing novolak resin

摘要

Provided an industrially excellent method of producing a phenol novolak resin having an ortho ratio of 30% or more by: (1) a method of reacting a phenol and an aldehyde using an oxalic acid catalyst at 110 to 160° C. under pressure; or (2) a method of reacting a phenol and an aldehyde under pressure while removing the heat of reaction by a condenser with controlling a pressure so that water or an organic solvent present in the reaction system is refluxed.