Vinyl alcohol copolymer, production method thereof, anti-dehydrating agent for cement slurry, and anti-dehydrating method for cement slurry

Abstract

A vinyl alcohol copolymer, wherein the vinyl alcohol copolymer includes a vinyl alcohol unit and a constituent unit derived from an unsaturated monomer (A), the unsaturated monomer (A) is at least one selected from the group consisting of an unsaturated carboxylic acid, a salt thereof, an anhydride thereof, and an alkyl ester thereof, a content of the constituent unit derived from the unsaturated monomer (A) with respect to total constituent units of the vinyl alcohol copolymer is 1.00 mol % or more and 5.00 mol % or less, and 70 mol % or more of the constituent unit derived from the unsaturated monomer (A) forms a lactone ring structure.

Dependencies are inferred from the claim text.