Patent ID: 8592623

Claim:
A process for the production of a polyester polyol comprising: a) mixing and reacting (A) at least one carboxylic anhydride, (B) diethylene glycol, and at least one of (C) (i) C 2 -C 4 glycol, other than diethylene glycol, and (ii) an aliphatic C 5 -C 12 dicarboxylic acid or (D) (i) a C 5 -C 10 glycol and (ii) at least one C 4 dicarboxylic acid to form an intermediate polyester polyol and b) adding more (B) diethylene glycol to the reacted mixture produced in step a) to form the polyester polyol product, wherein a molar ratio of (B) to (A) in step a) is from 1.5:1 to 0.7:1, the amounts of (A) plus (B) in step a) constitute from 66 to 90% by weight of total weight of (A) plus (B) plus (C)(i) plus (C)(ii) plus (D)(i) plus (D)(ii), and the intermediate polyester polyol product from step a) has a higher molar mass than the product polyester polyol from step b).