Polyester polymer

A polyester polyol comprising a reaction product obtained from components comprising:

• (i) a polyol comprising 3 or more hydroxyl groups;
• (ii) a dicarboxylic acid or an anhydride thereof that comprises 3 carbon atoms or fewer between the carboxylic acid groups or the anhydride thereof;
• (iii) a monocarboxylic acid or an anhydride thereof;
• (iv) from 0 weight % to less than 10 weight % of a diol, based on total solids of the components included to obtain the reaction product;
• and
• (v) from 0 weight % to less than 10 weight % of a dicarboxylic acid or an anhydride thereof that comprises greater than 3 carbons between the carboxylic acid groups or the anhydride thereof, based on total solids of the components included to obtain the reaction product;
• wherein a molar ratio of (i)+(iv) to (ii)+(v) ranges from 1.08:1 to 1.75:1, such as 1.08:1 to 1.67:1, and a molar ratio of (i)+(iv) to (iii) ranges from 1.25:1 to 4:1, such as 1.3:1 to 2.5:1, and
• wherein the reaction product comprises a hydroxyl value of from 60 to 300 mg KOH/g, such as 90 to 280 mg KOH/g, and an acid value of less than 15 mg KOH/g.