Intumescence-based coating, fire resistance

These coatings provide the most effective fire-resistant system available but originally were deficient in paint color properties. Since, historically, the intumescence producing chemicals were quite water-soluble, coatings based thereon did not meet the shipping can stability, ease of application, environmental resistance, or aesthetic appeal required of a good protective coating. 

At an optimum addition level of only 1.5 w t %, nano-size magnesium-aluminum LDHs have been shown to enhance char formation and fire-resisting properties in flame-retarding coatings, based on an intumescent formulation of ammonium polyphosphate, pentaerythritol, and melamine.89 The coating material comprised a mixture of acrylate resin, melamine formaldehyde resin, and silicone resin with titanium dioxide and solvent. It was reported that the nano-LDH could catalyze the esterification reaction between ammonium polyphosphate and pentaerythritol greatly increasing carbon content and char cross-link density. 

All the above formulations have been investigated and evaluated on perforated and unperforated Celotex fiberboard. Results demonstrate that a satisfactorily formulated intumescent water- or oil-base paint is the best type of paint to apply to acoustical fiber board to secure optimum fire or flame resistance. These paints, by their intumescent nature, tend to close the openings in the acoustical fiber board and insulate the basic fiber under the coating. 

Few recent scientific papers are devoted to resistance to fire using intumescent coating, but a growing market for this application exists. A rapid survey of the literature shows that the formulations used are always based on the well-known trio APP/PER-Melamine. Nevertheless a lot of work remains to be done to understand and to quantify the mechanisms of intumescence acting as protective heat barrier. 

A new US company based in Hudson, Massachusetts has developed intumescent coatings and additives that enhanee the fire properties of plastic and composite structures. Avtec Industries now offer Thermashield mastic coatings that can withstand temperatures in excess of 1200 °C for sustained periods. The coatings material is non-toxic and does not flake, peel or chip. It is resistant to water and chemieal attack and is claimed to withstand multiple high-impact shocks. 

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