| 摘要 |
PURPOSE:To make it possible to lower the halogen content of an epoxy resin without causing undesirable side reactions such as opening of an epoxy group, by retreating a specified crude epoxy resin with a caustic alkali while specifying the water content in the reaction system in this treatment. CONSTITUTION:A crude epoxy resin produced from a bisphenol having a substituent in the position ortho to the phenolic hydroxyl group and an epihalohydrin is retreated with a caustic alkali. In this treatment, the water content of the reaction system is adjusted to 3.0wt% or below (preferably, 2.0wt% or below) based on the crude epoxy resin. When the water content in the reaction system is higher than said value, it is preferable to distil it together with the solvent from the system.
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