Method for producing highly polymerizable N-vinyl carboxylic acid amide monomer

Abstract

Provided is a method for producing a highly polymerizable N-vinyl carboxylic acid amide monomer by efficiently purifying N-vinyl carboxylic acid amide.　The method for producing a highly polymerizable N-vinyl carboxylic acid amide monomer comprises: (A) a step in which a crude N-vinyl carboxylic acid amide monomer containing 50-88 mass% of an N-vinyl carboxylic acid amide monomer is melted by heating and then precipitated by cooling (cooling crystallization), and a precipitated N-vinyl carboxylic acid amide monomer crystal is solid-liquid separated (step (A)); and (B) a step in which the N-vinyl carboxylic acid amide monomer crystal separated in step (A) is further dissolved in a mixed solvent of methyl ethyl ketone and C6-7 aliphatic hydrocarbon, and then subjected to crystallization (solvent crystallization) and solid-liquid separation to recover a purified N-vinyl carboxylic acid amide monomer (step (B)), wherein the mass ratio of methyl ethyl ketone / N-vinyl carboxylic acid amide monomer crystal in step (B) is 0.01-0.5, and the mass ratio of C6-7 aliphatic hydrocarbon / N-vinyl carboxylic acid amide monomer crystal in step (B) is 0.5-3.0.

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