Method of producing polyetherester monomer and cement dispersants

摘要

Polyetherester monomers of a high quality are produced by causing an esterification reaction of polyalkyleneglycol with a closed end of a specified kind which has been refined so as to contain residual free acid by less than 0.03 weight %, as converted to acetic acid, and unsaturated carboxylic acid of another specified kind by using a specified amount of an acid catalyst under a heated and reduced-pressure condition in the absence of solvents and in the presence of p-benzoquinone and/or phenothiazine while distilling away generated water. Cement dispersants are produced by using water-soluble vinyl copolymers obtained by a radical copolymerization reaction between such polyetherester monomers and vinyl monomers.