| abstract |
PROBLEM TO BE SOLVED: To provide a vinyl acetal polymer excellent in water resistance and compatibility with a plasticizer, an interlayer for laminated glass, a binder for ceramic molding, a binder for ink and paint, and a heat developable feeling comprising the vinyl acetal polymer. Provide an optical material. SOLUTION: The composition contains 1 to 15 mol% of an α-olefin unit, the content of 1,2-glycol bond is 1 to 3 mol%, the degree of polymerization is 100 to 2000, and the degree of saponification is 80.0 to 99.99. The above-mentioned problem is solved by a vinyl acetal polymer having a degree of acetalization of 45 to 80 mol%, which is obtained by acetalizing a vinyl alcohol polymer of mol%. [Selection diagram] None |