Hydrocarbon blown polyurethane foam formulation giving desirable thermal insulation properties

A method of forming an insulating member, comprising:

• forming a composition, comprising:
• an organic polyisocyanate;
• at least about 20% by weight of an aromatic polyester polyol based on the total weight of the composition;
• a hydrocarbon blowing agent;
• a first catalyst comprising a salt selected from the group consisting of a carboxylate salt of an alkali metal, a carboxylate salt of an alkaline earth metal, a carboxylate salt of a quaternary ammonium, and combinations thereof;
• a tertiary amine selected from the group consisting of a trialkylamine, an alkyl amine, an alkylaryl amine, an aliphatic polyamine, diazabicyclooctane, 1,4-ethylene piperidine, N-methylimidazole, 1,2-dimethylimidazole, 1,8-diazabicyclo(5,4,0)undecene-7, an ether amine, a saturated heterocyclic amine, and a combination thereof;
• wherein a molar ratio of the first catalyst to the tertiary amine is less than about 1.0, wherein the tertiary amine is present in an amount of at least 4.0 millimoles per 100 grams of the composition to 9.46 millimoles per 100 grams of the composition, and the composition has an isocyanate index of about 200 to 500;
• and
• dispensing the composition onto a substantially flat moving surface.