Relevant factors in scorch generation in fire retarded flexible polyurethane foams - I. Amino group reactivity

Use of water instead of chlorofluorocarbons in foaming processes results in increased slabstock temperature and concomitant scorching which often occur more easily in the fire retardant foams. However, not all fire retardants aggravate scorch. Interaction of a number of fire retardants with aniline, which was chosen as a model compound simulating the -NH2 groups always present in water-blown polyurethane foams, has been examined by several experimental techniques. The reported results highlight that this interaction leads to alkylation of the amine and to the formation of phosphoric acid or alkyl phosphoric acids or hydrogen chloride in the case of chloroalkyl phosphates. As this interaction occurs the scorch phenomenon occurs as well in the fire retardant foams, therefore the scorch could be possibly connected with this interaction. It is likely that N-alkyl anilines or HCl or phosphoric acids can promote scorch. (C) 2004 Elsevier Ltd. All rights reserved.