METHOD FOR SAPONIFYING CROSSLINKED ACRYLONITRILE POLYMER BEAD, USE OF OBTAINED BEAD AND WEAK ACID CATION EXCHANGER

摘要

PROBLEM TO BE SOLVED: To provide a method for saponifying with an alkali a crosslinked polymer bead, which is well-known as an acrylonitrile bead polymer containing an acryl unit, and to provide a use of the saponified acrylonitrile polymer bead as a weak acid ion exchanger which is low colored and whose residual nitrogen content is low.

SOLUTION: The method for saponifying the crosslinked acrylonitrile polymer bead using an alkali saponifying agent is to start the saponification at a temperature T1 of 70-120°C and to complete the saponification at a temperature T2 of 120-180°C after being achieved a degree of saponification of 65%, wherein T2 is kept at least 10°C higher than T1.

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