Purification of polyether-polyol
AssigneeDai-Ichi Kogyo Seiyaku Co., Ltd.
InventorsShigeo Mori, Takeshi Fujita
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Abstract
Crude liquid polyether-polyols containing an alkaline catalyst are purified by the steps of: neutralizing said crude liquid polyether-polyol with a mineral acid having a dissociation constant of greater than 10.sup.-3 at 25.degree. C. distilling off water from said liquid, and filtering the same. The improvement resides in the step of adding a hydrate of a metal salt of said mineral acid to the liquid polyether-polyol at a stage before the distillation step for promoting the crystal growth of a salt formed from said alkaline catalyst by the neutralization.
Claims10
In a method for purifying crude polyether-polyols containing an alkaline catalyst comprising the steps of:
- neutralizing said crude liquid polyether-polyol with a mineral acid having a dissociation constant of greater than 10.sup.-3 at 25.degree. C.,
- distilling off water from said liquid, and
- filtering the same, the improvement which comprises adding a hydrate of a metal salt of said mineral acid to said liquid polyether-polyol at a stage before the distillation step for promoting the crystal growth of a salt formed from said alkaline catalyst by the neutralization.
Dependencies are inferred from the claim text.