| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester polyol having a low viscosity and a low hydroxyl value, which does not freeze even during a low-temperature period such as the winter season, and to provide a method of producing hard polyurethane foam excellent in flame retardancy.SOLUTION: The polyester polyol is obtained by esterification of a carboxylic acid component containing isophthalic acid and/or terephthalic acid and an alcohol component containing polyethylene glycol having number average molecular weight of 200 to 1,000 and polypropylene glycol having a number average molecular weight of 200 to 1,000. The polyester polyol has a hydroxyl value of 50 to 150 mgKOH/g and a viscosity of 2,000 mPa s or less at 25°C. |
