| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polyvinyl acetal resin, which attains high reaction efficiency of an aldehyde, can reduce the amount of the aldehyde used by inhibiting side reactions other than acetalization reaction, and can produce in a short time a polyvinyl acetal resin having a high degree of acetalization and hardly causing decrease in the degree of polymerization and coloring such as yellowing.SOLUTION: A method for producing a polyvinyl acetal resin includes a step of bringing a mixed liquid comprising a polyvinyl alcohol resin, an aldehyde and an aqueous medium into acetalization reaction under high temperature/high pressure conditions of a temperature of 100-200°C and a pressure of 0.1-3 MPa, wherein the hydrogen ion concentration of the mixed liquid in an environment at room temperature and atmospheric pressure is adjusted to 5×10to 1×10mol/L, and the content of the aldehyde is 0.6-1.2 times that of the polyvinyl alcohol resin by molar ratio. |
