塑料 聚氨酯生产用芳香异氰酸酯 酸度测定

[中文适用范围]： 本标准规定了聚氨酯原料用芳香族异氰酸酯和预聚物酸度的测定方法。 方法 A 是一种没有空白的直接滴定法，主要适用于由粗制或改性亚甲基双（4-苯基异氰酸酯）、多亚甲基多苯基异氰酸酯和甲苯二异氰酸酯衍生而来的具有中等到高（> 100 μg/g）酸度的产品。 方法B适用于衍生自亚甲基双(4-苯基异氰酸酯)、多亚甲基多苯基异氰酸酯和甲苯二异氰酸酯的具有低酸度(<100μg/g)的精制、粗制或改性异氰酸酯，并采用空白。 这些方法也可用于甲苯二异氰酸酯、亚甲基双(4-苯基异氰酸酯)和多亚甲基多苯基异氰酸酯的异构体混合物。 如果采取预防措施来验证适用性，其他芳香族异氰酸酯也可以通过此方法进行分析。 [外文原描述]： This International Standard specifies methods for the measurement of the acidity of aromatic isocyanates and prepolymers used as polyurethane raw materials. Method A is a straightforward titration without a blank and is primarily applicable to products derived from crude or modified methylene-bis-(4-phenylisocyanate), polymethylene polyphenylisocyanates and toluene diisocyanate having moderate to high (> 100 mg/g ) levels of acidity. Method B is applicable to refined, crude or modified isocyanates derived from methylene-bis-(4-phenylisocyanate), polymethylene polyphenylisocyanate and toluene diisocyanate having low (< 100 mg/g ) levels of acidity, and a blank is employed. These methods can also be used for isomeric mixtures of toluene diisocyanate, methylene-bis-(4-phenylisocyanate) and polymethylene polyphenylisocyanate. Other aromatic isocyanates may be analysed by this method if precautions are taken to verify suitability.