Liquid carbodiimide- and uretonimine-isocyanurate-containing polyisocyanate compositions and microcellular foams made therefrom

摘要

The invention relates to carbodiimide- and/or uretonimine-isocyanurate-containing polyisocyanates, to the process for their preparation, and to microcellular foams prepared therefrom. These compositions may be prepared in the presence of the appropriate catalyst by (a) a partial trimerization of a mixture of polyisocyanate and carbodiimide and uretonimine containing polyisocyanate with trimer catalyst to the desired free isocyanate level, (b) sequential, partial carbodiimidization followed by partial trimerization of a polyisocyanate to the desired free isocyanate level (c) sequential partial trimerization of a polyisocyanate followed by partial carbodiimidization, (d) simultaneous conversion using the mixed catalyst system of carbodiimide and isocyanurate catalysts reacted to the desired free isocyanate level, and (e) blending liquid polyisocyanate with the carbodiimide and uretonimine containing polyisocyanate and isocyanurate containing polyisocyanate to the desired isocyanate level.