The regulations stipulate that only fire protection Class B1 building materials may be used in escape routes – these include foyers. Similarly strict requirements already apply to other areas (e.g. meeting locations) and it is already foreseeable that these requirements will apply to other areas in the future, in particular in the transport sector.
Our investigations were carried out on seven commercially-available and 19 modified aqueous PU binders. In addition, a commercial PVC paste was also evaluated during the preliminary tests. The modifications undertaken were organic modifications (phosphor-based) to the binder system, inorganic modifications with silicates and silicon dioxide nanoparticles, and hybrid modifications using a sol-gel process in combination with inorganic constituents.
The behaviour of the various binders in reaction to the intumescence process was investigated using a commercial intumescent mixture and six intumescent aggregate mixtures. The intumescent mixtures were incorporated in 30 to 50 percent by mass in relation to the overall recipe. The production of the recipes was carried out with the help of a laboratory disperser. The compatibility and the curing were tested by applying the mixture to a glass plate. The fire behaviour was investigated under laboratory conditions in accordance with WKI methods and in a small-furnace test in accordance with the standard DIN 4102.
The commercial intumescent mixture could not be incorporated into any of the binders – each attempt resulted in phase separation. The incorporation of the aggregate mixtures 1,2 and 3 in the PVC paste resulted in homogeneous coating compounds and the intumescent reaction during fire-testing was not impaired. At an aggregate concentration of 50%, the majority of the PU coatings showed large cracks. In order to determine the binder proportion which would not result in a significant deterioration during fire-testing, a series of test were carried out in which the proportion of the organically-modified PU binder was varied. The most favourable intumescent aggregate concentration was determined thereby to be 30%. This also led to an improved layer. However, this result is not applicable for all PU types. For all the aggregate mixtures in combination with the PU, a significantly lower amount of swelling was determined compared to the PVC paste. A large majority of the commercial PU binders formed only a slight foam layer. The insulation effect during fire-testing resulted mainly from cavity formulation with a foam surface layer of varying thickness. With the organically-modified binders, the swollen layers also contained cavities. The results for the inorganically-modified and hybrid-modified binders fluctuated most strongly. The best fire protection was provided by two hybrid modifications and an organic modification.