Patent ID: 8048935

Claim:
An all-liquid foam-forming system for forming a rigid, high density polyurethane foam having a density of at least about 5 pcf and an ASTM E-84 Class 1 rating, consisting of: a first liquid part (A) consisting of polymethylene polyphenylene polyisocyanates; and a second liquid part (B) consisting of at least one liquid aromatic polyester polyol having an hydroxyl value of 295-350 mg KOH/gram and a hydroxyl functionality of 2.0-2.2, said at least one liquid aromatic polyester polyol being present in an amount of at least 26% by weight of the combined weight of parts (A) and (B), diethylene glycol, a halogen-substituted organic phosphate and a brominated organic compound, water, at least one liquid tertiary amine for catalyzing reaction between said first liquid part (A) and said aromatic polyester polyol, a triethanolamine propoxylated polyol, from 0 to no more than 2.0% by weight of one or more polyether polyols based on the combined weight of part (A) and part (B), and, optionally, a liquid surfactant; wherein the system has an NCO/OH ratio of 0.95:1 to 1.2:1 and parts (A) and (B) are provided at a mix ratio (B/A) of 1:0.9 by weight and react to form the rigid, high density polyurethane foam having the ASTM E-84 Class 1 rating and a density of at least about 5 pcf.