Low temperature stable polymethylene polyphenylene polyisocyanates are composed of crude polymethylene polyphenylene polyisocyanate containing from about 50 to about 80 percent by weight 2-ring diphenylmethane diisocyanate wherein from about 65 to about 93 weight percent of the 2-ring diisocyanate is 4,4'- and from about 7 to about 35 weight percent is 2,4'- and furthermore the composition contains from about 1 to about 5 weight percent carbodiimide- uretonimine structure. The polyisocyanates are useful in preparing polyurethane foams.
低温稳定聚亚
甲基多
苯基多
异氰酸酯由粗聚亚
甲基多
苯基多
异氰酸酯组成,其中含有约 50%至约 80%(重量百分比)的 2-环
二苯基甲烷二
异氰酸酯,其中约 65%至约 93%(重量百分比)的 2-环二
异氰酸酯为 4,4'-,约 7%至约 35%(重量百分比)的
2,4'-,此外,该组合物还含有约 1%至约 5%(重量百分比)的
碳二
亚胺-
脲基
亚胺结构。多
异氰酸酯可用于制备聚
氨酯泡沫。