POLYISOCYANATE POLYADDITION POLYOL MANUFACTURING PROCESS AND PRODUCT

摘要

PIPA polyols are made in a two-step process. In the first step, a base polyether polyol and a polyisocyanate are reacted to form a mixture that contains unreacted base polyol, unreacted polyisocyanate and adducts of the base polyol and polyisocyanate. A low equivalent weight polyol is then added and reacted in a second step to form the dispersion. The process unexpectedly produces a stable dispersion of the fine PIPA particles in the base polyol, even when the base polyol contains mostly secondary hydroxyl groups. The process also permits the tuning of product viscosity by increasing or decreasing the extent of reaction in the first step.