本国际标准规定了芳香族异氰酸酯和芳香族化合物酸度的测量方法 用作聚氨酯原料的预聚物。方法A是一种没有空白的直接滴定法，并且 主要适用于从粗亚甲基或改性亚甲基双-（4-苯基异氰酸酯）、聚亚甲基衍生的产品 具有中等至高（>；100 mg/g）酸度的聚苯异氰酸酯和甲苯二异氰酸酯。方法B是 适用于从亚甲基双-（4-苯基异氰酸酯）、聚亚甲基衍生的精制、粗加工或改性异氰酸酯 酸度较低（<；100 mg/g）的聚苯异氰酸酯和甲苯二异氰酸酯，使用空白。 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）的异构混合物 和聚亚甲基聚苯异氰酸酯。其他芳香族异氰酸酯可通过该方法进行分析，如果 采取预防措施以验证适用性。

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.