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聚甲撑多苯基异氰酸酯(PAPI)属聚氨酯类化合物。聚氨酯是由多元异氰酸酯和多元羟基化合物作用而制成,其主要单体为二异氰酸酯。二异氰酸酯类化合物对上呼吸道、眼结膜以及皮肤均有不同程度的刺激作用,其刺激作用随化合物的分子量增大而减弱。其中甲苯二异氰酸酯(TDI)还有明显的致敏作用,主要为过敏性哮喘和皮炎。因此,国内外已大量应用二苯基甲烷二异氰酸酯(MDI)及PAPI代替TDI,因其蒸气压低(25℃时MDI为0.000005mmHg,PAPI为0.000003 mmHg),
Polymethylene polyphenyl isocyanate (PAPI) is a polyurethane compound. Polyurethane is made by the action of polyisocyanate and polyhydroxy compound, the main monomer is diisocyanate. Diisocyanates on the upper respiratory tract, conjunctiva and skin have different levels of stimulation, the stimulating effect with the compound molecular weight increased and weakened. Toluene diisocyanate (TDI) which also significant sensitization, mainly allergic asthma and dermatitis. Therefore, at home and abroad, diphenylmethane diisocyanate (MDI) and PAPI have been widely used in place of TDI because of their low vapor pressures (MDI of 0.000005 mmHg at 25 ° C. and PAPI of 0.000003 mmHg)