On account of its low water solubility, Exolit AP 422 is particularly suitable as an ”acid donor” for intumescent coatings. Other essential components of intumescent systems include a binder, a carbon donor (e.g. pentaerythritol) and a blowing agent (e.g. melamine).
On exposure to flame, intumescent coatings form a carbonaceous foam which effectively shields the underlying material from temperature increases.
Steel structures coated with intumescent paints can meet the requirements of fire resistance classes specified in EN, DIN, BS, ASTM and others.
The application of Exolit AP 422 based intumescent coatings on wood or plastics enables these materials to qualify for Building Material Class B (DIN EN 13501-1).
Exolit AP 422 imparts a good flame-retardant effect to adhesives and sealants when it is incorporated into the base formulation at the rate of 10 - 20 %.
Exolit AP 422 is a suitable non-halogenated flame retardant for polyurethane foams. If handling of Exolit AP 422 as a solid is not possible we recommend the dosage of the flame retardant by preparing an Exolit AP 422/polyol-suspension. Because of the low acid number of Exolit AP 422, it is also possible to incorporate this flame retardant in an Exolit AP 422/isocyanate suspension.
To prevent the solids from settling, the Exolit AP 422 suspensions should be stirred or circulated by pump. The stirrers commonly found in service tanks are adequate for this purpose.
Exolit AP 422 has an excellent flame-retardant effect in cellulose-containing materials such as paper and wood products. With chipboard products, the DIN EN 13501-1 classification can be achieved by adding 15 - 20 % Exolit AP 422.
Because of its high heat stability, Exolit AP 422 is an essential component in intumescent formulations for thermoplastics, particularly polypropylene, for which the classification UL 94-V0 is specified for applications in the electrical sector.
Casting resins and composites based on epoxy resins or unsaturated polyester resins achieve the classification UL 94-V0 with Exolit AP 422. Combinations of AP 422 with ATH show synergistic effects in UL94 and LOI tests.