| 摘要 |
A polyol formulation comprising 30 to 55 wt% of a polyol of a flexible type having a number average molecular weight in the range of from 1100 to 3800, a hydroxyl value in the range of from 60 to 120 mg KOH/g and an ethylene oxide content of less than 75 wt% and 45 to 70 wt% of a polyol of a rigid type having a number average molecular weight of less than 1000 and a hydroxyl value of greater than 300 mg KOH/g. The method for preparing the above formulation comprises mixing together said flexible polyol and said rigid polyol in the amounts indicated. The formulation is very useful to prepare a semi-flexible polyurethane foam having a softening temperature of 115 DEG C or above. Such foam can be prepared by reacting a polyisocyanate component with the polyol formulation or with said flexible polyol and said rigid polyol simultaneously or consecutively. The foam exhibits a retarded increase of thermal conductivity in time and is very useful as pipe insulation material. |
