| 摘要 |
PURPOSE:To obtain the titled resin useful as an intermediate film for bonding safety glass, sealing material for solar cell, etc., by saponifying an ethylene-vinyl acetate copolymer with an alkali alcoholate in the presence of a specific amount of water, modifying the saponified copolymer with an acid, and treating modified copolymer with water. CONSTITUTION:An ethylene-vinyl acetate copolymer (EVA) is dissolved in an organic solvent (e.g., xylene, etc.) having >=50 deg.C boiling point, mixed with a lower alcohol, an alkali alcoholate, and 0.1-3mol based on the alcoholate of water, and saponified usually at 40-60 deg.C for 0.5-5hr. Low-boiling substances in the reaction solution are optionally distilled away, the reaction solution is reacted with an unsaturated carboxylic acid or a dicarboxylic acid anhydride usually at 50-150 deg.C for 0.1-5hr, so that the saponified copolymer is modified. Then, water is added to the modified acidic reaction solution with vigorous stirring, the reaction solution is sufficiently brought into contact with water, to give the aimed resin having >=90% percent transmission of the whole light rays of a sheet with 1.0mm thickness, <=3% haze, and <=3 yellowness.
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