PURPOSE: To permanently reduce the content of acetaldehyde in a dispersion without spoiling the functional properties of the dispersion by hydrolyzing subsequently a vinyl ester (co)polymer at a weak alkaline pH value and a high temperature.
CONSTITUTION: When the residual monomer concentration of a homopolymer or a copolymer particularly of vinyl acetate is reduced to 0.01% by weight or less based on its dispersion, to permanently reduce similarly the content of acetaldehyde frequently present in vinyl ester (co)polymers without spoiling the functional properties characteristic of dispersions, the dispersion is subsequently hydrolyzed at a weak alkali pH value and an elevated temperature, so that the residual monomer vinyl ester contents that can be hydrolyzed under alkaline conditions are decomposed completely to carboxylic acids and acetaldehyde while the major part of the corresponding vinyl ester units in the (co)polymer molecules of the polymer dispersion particles remains unchanged.
HERUMUUTO RINNO
BERUNHARUTO MOMUPERU
