- Author
-
Parsonage, J. R.
- Title
- Flame Retardant Polyurethane Foams. European Patent Application.
- Coporate
- Thames Polytechnic, London, England
- Report
-
European Patent Application 0502689A1
March 3, 1992
12 p.
- Keywords
-
polyurethane foams
|
flame retardants
- Abstract
- This invention relates to flame retardant polyurethane foams. Both flexible and rigid polyurethane foams have found wide use, but their flammability, with resulting toxic emissions has caused considerable difficulties. This is especially so for flexible foams which, on burning, depolymerise and melt to form a liquid which flows, burns, volatalises and causes flashover, ie the formation of a sudden sheet of flame. In an attempt to avoid these difficulties, many flame retardants have been incorporated in the polyurethane foam, and a variety of mechanisms operate in which the retardants may act as any one or more of thermal barriers, depolymerisation inhibitors, flow inhibitors and moisture sinks. Fire retardants which have been tried to date include inorganic additives, such as cement, graphite, talc, calcium oxide, hydrated alumina, silicates, silica and phosphorus compounds, and organic additives such as halogen compounds and melamine. The use of a mixture of inorganic and organic fire retardants is also known; see for example JP-A-53-26898 which describes the use of an alkali silicate powder, together with an organic halogen compound as flame retardant. Some additives adversely affect the polymerization reaction and/or foaming process, especially where the additive carries water. In particular, the water tends to react with the isocyanate in the reaction mixture. There are also some additives which seriously impair the mechanical and other properties of the foam. For example, although hydrated alumina acts as an efficient water sink, it produces an adverse feel and prevents the formation of a low density foam, while graphite, in addition to being expensive, gives a black colouration. Other additives which we thought might prove useful, for example, cement, although inhibiting the onset of ignition, actually promote burning because, although they form a rigid char, this acts as a wick for the flame. Thus weight and heat loss are actually increased.