POLYVINYL ALCOHOL BASED POLYMER AND METHOD OF MANUFACTURING THE SAME

摘要

A polyvinyl alcohol-based polymer is provided, which can change a solubility to water remarkably by a small temperature change, therefore has a low solubility to low temperature water and a rapid solubility to high temperature water. And a process for producing the polyvinyl alcohol-based polymer is also provided. The polyvinyl alcohol-based polymer is produced by the process comprising the steps of: performing a transesterification of a polyvinyl ester-based polymer and an alcohol in a reaction mixture of the polyvinyl ester-based polymer, the alcohol, and a basic compound to precipitate at least one part-transesterified polymer from the reaction mixture; performing the transesterification again in the reaction mixture containing the precipitated polymer. A temperature of the reaction mixture when the transesterified polymer starts precipitating to the transesterification stops is 75-150deg.C. And a temperature of the reaction mixture when the transesterification starts to the precipitation starts is 40-165deg.C.