| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of a polyvinyl acetal resin capable of producing a polyvinyl acetal resin reduced in a content of residual metals and that of residual acids without requiring any neutralization process; and a polyvinyl acetal resin produced by this method.SOLUTION: A method of producing a polyvinyl acetal resin includes: a process A of subjecting a mixture solution, which contains a polyvinyl alcohol resin, an aldehyde compound and an aqueous medium and has hydrogen ion concentration adjusted to ≤1×10mol/L in an atmospheric environment at room temperature, to an acetalization reaction in a high-temperature high-pressure condition at a temperature of 100-200°C and a pressure of 0.1-3 MPa to synthesize a polyvinyl acetal resin; and a process B of molding the resultant polyvinyl acetal resin into the tube shape and washing it with a detergent at a temperature higher than a glass transition temperature of the resin. A polyvinyl acetal resin is also provided. |
