To obtain an aliphatic polyvinyl ester having low polymerization degree under industrially advantageous conditions without affecting adverse influence such as malodor or coloring on qualities of the ester by adding a specific acid or its salt in a specific ratio as a chain transfer agent to an aliphatic vinyl ester.
Allylsulfonic acid, methallylsulfonic acid or their salts (e.g. sodium allylsulfonate or sodium methallylsulfonate) in an amount of 0.05-1.0mol% as a chain transfer agent is added to an aliphatic vinyl ester (e.g. vinyl acetate) to polymerize the aliphatic vinyl ester. Furthermore, the resultant objective aliphatic polyvinyl ester is preferably further saponified to provide the objective polyvinyl alcohol. In the above process, the polymerization is preferably carried out at about 60°C by using a solvent such as methanol and a radical polymerization initiator.
NAKAJIMA TAKASHI
NOGUCHI HIROSHI
