Polyoxazolidone foams

The oxazolidone linkage is a thermally stable and difunctional linkage that has been used for modifying isocyanurate foams (61, 63). Unmodified oxazolidone foams are expected to have improved properties such as temperature stability, flame retardance, and low friability. An attempt to obtain unmodified polyoxazolidone foams was reported (98). The formulation employed is shown in Table 31. 

A premix was prepared by blending the bisphenol A-epichloro-hydrin adduct, silicone surfactant and CFC-llA. Into the premix, polymeric isocyanate and the complex catalyst were added and the mixture was immediately agitated vigorously to produce a foamed material. The resulting foam had a density of 40 kg/m with fine cell structure. 

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Isocyanate-based foams include polyurethane, polyisocyanurate, polyurea, polycarbodiimide, polyamide, polyimide, and polyoxazolidone foams. 

Physical blowing agents may be classified as CFCs (chlorofluoro-carbons), HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbon ethers) and non-fluorine-containing organic liquids. These fluorinated blowing agents can also be used in foaming polyisocyanurate foams, polyoxazolidone foams, and polyurea foams. 

These polyoxazolidones represent a new generation of isocyanate derived polymers which have characteristic thermal stability properties. They are useful in adhesives, elastomers, coatings, foams, and electrical applications. Numerous other applications will no doubt be found for them. 

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