| abstract |
A method for producing a polyester polyol is disclosed. The method comprises reacting phthalic anhydride with a diol selected from the group consisting of ethylene glycol, propylene glycol, 1,3-propanediol, 2-meth-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, polyethylene glycols having a number average molecular weight within the range of 200 g/mol to 600 g/mol, and mixtures thereof at a diol to phthalic anhydride molar ratio within the range of 1.1 to 1.6. The resulting o-phthalate polyester polyol has a hydroxyl value in the range of 18 to 400 mg KOH/g, an acid value in the range of 0.2 to 5.0 mg KOH/g, and 1 wt. % or less of cyclic esters. |