EVA emulsion is typically used as the basis resin in aqueous intumescent coatings for steel structure fireproof, along with the flame retardant system of ammonium polyphosphate, melamine, pentaerythritol, and titanium dioxide as filler. One expansion foam layer will be created during combustion, separating the fire from fresh air and stopping the energy from inside steel or wood, etc., parts. However, a high foam rate may lessen the strength of the foam layer, making it more likely to break easily and emit smoke and harmful fumes.
Melamine Borate (MB), an inorganic smoke suppressant synergist, is a viable option to be included in this flame retardant system. MB is possible to lessen the drop and reinforce the foam layer, which will undoubtedly lessen the density of the smoke and have high performance in actual use.
The difference in the carbon layer by coating % is shown in the image above.
Sample No.1 (1% MB) had a clearly broken foam layer; Sample No.2 (2% MB) displayed a well-even, compact layer with flawless shape; and Sample No.3 (3% MB) had a compact layer with some cracking.
We can see from the test table above that MB delays the time at which smoke is released.
Zero coating releases smoke at 10S, whereas 1% MB delays the release of smoke until 33S (late 23S) and significantly lowers the smoke density, which is low down to 13. MB effectively promotes Char generation during the burning in order to lower the volatilized material content in the gas.
based on the results of the test, we can conclude that 1% Melamine Borate is the best dosage to encourage char generation and enhance thermostability. At 800 °C, the carbon residue is around 45%, resulting in a foam layer that is evenly distributed and compact, as well as more stable foam hole structure and longer thermal insulation duration. The 2 mm intumescent coating has a long thermal insulation time of 135 minutes and a low smoke density of 13.
