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

Abstract

Provided is a method whereby an N-vinyl carboxylic acid amide can be efficiently refined to manufacture a highly polymerizable N-vinyl carboxylic acid amide monomer.　This method for manufacturing a highly polymerizable N-vinyl carboxylic acid amide monomer is characterized by including: (A) a step for melting, by heating, a crude N-vinyl carboxylic acid amide monomer including 50-88 mass% of an N-vinyl carboxylic acid amide monomer, then cooling to precipitate the N-vinyl carboxylic acid amide monomer (cooling crystallization), and solid-liquid separating the precipitated N-vinyl carboxylic acid amide monomer crystals (step (A)); and (B) a step for further dissolving the N-vinyl carboxylic acid amide monomer crystals separated in step (A) in a solvent mixture of ethyl acetate and a C6-7 aliphatic hydrocarbon, and then performing crystallization (solvent crystallization) and solid-liquid separation to recover an N-vinyl carboxylic acid amide monomer purified product (step (B)), the ethyl acetate / N-vinyl carboxylic acid amide monomer crystal mass ratio in step (B) being 0.01-0.5 inclusive, and the C6-7 aliphatic hydrocarbon / N-vinyl carboxylic acid amide monomer crystal mass ratio in step (B) being 0.5-3.0 inclusive.

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