Hydrocarbon or hydrofluorocarbon blown ASTM E-84 class i rigid polyurethane foams

Abstract

The present invention provides a rigid polyurethane foam formed by the reaction product, at an isocyanate index of about 160 or less, of a polyisocyanate, a polyol component containing an aromatic polyester polyol, and a sucrose-initiated polyether polyol and a flame retardant component made from a chlorine-containing combustion modifier and a bromine-containing combustion modifier in the presence of a hydrocarbon or hydrofluorocarbon blowing agent. The inventive polyurethane foam contains, based on the weight of the foam, at least about 3 wt. % chlorine, from about 1 wt. % to about 2 wt. % bromine and less than about 1 wt. % phosphorus, and exhibits good properties, good processing and good adhesion to metal whilst satisfying the ASTM E-84 Class I burn requirement.

Description

field of invention [0001] This invention relates generally to polyurethanes, and more particularly to hydrocarbon or hydrofluorocarbon blown polyurethane foams meeting the requirements of ASTM E-84 for Class I materials. Background of the invention [0002] For many years, the primary blowing agent used to foam polyurethane foams has been chlorofluorocarbons ("CFCs"). These blowing agents were phased out after they were determined to pose a threat to stratospheric ozone. After CFCs were phased out, the most commonly used type of blowing agent became hydrogenated chlorofluorocarbons ("HCFCs"). Although these blowing agents are considered to be more environmentally friendly blowing agents, HCFCs still have a small ozone depleting potential ("ODP") and, therefore, are also mandated to be phased out. [0003] To date, metal faced foam board manufacturers have used 1,1-dichloro-1-fluoroethane (HCFC-141b) as a blowing agent for polyurethane foams. Manufacturers of discontinuous...

AI Technical Summary

Problems solved by technology

However, to date, meeting the Class I combustion requirements of ASTM E84 has been problematic for PUR foams blown with HFCs and hydrocarbons

Additionally, many older foam processing machines can only operate at a fixed volume ratio of 1:1 or 1.25:1 isocyanate to polyol

This greatly limits the use of this type of machine in PUR systems, especially when higher water contents are used in the formulation