| 摘要 |
The present invention relates to stable liquid, allophanate-modified, partially trimerized diphenylmethane diisocyanates, the prepolymers of these stable liquid, allophanate-modified, partially trimerized MDI's, and to processes for the preparation of these compositions. These allophanate modified partially trimerized diphenylmethane diisocyanates comprise the reaction product of a diphenylmethane diisocyanate and an organic compound i n the presence of a catalytic amount of one or more trimer catalysts, one or more allophanate catalysts, one or more allophanate-trimer catalysts and mixtures thereof. The prepolymers are the reaction product of the stable liquid, allophanate-modified, partially trimerized MDI's with a suitable isocyanate-reactive group containing compound.
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