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REVIEW


UPDATE


Clockwise from top left: Lab test of a dispersion


Top right: Modern buildings often feature steel skeletons – but when the temperature reaches 500°C, steel frames soften rapidly. To prevent them from buckling within minutes during a fire, they are provided with special fire protection coatings, allowing them to resist a fire for much longer


Middle: In case of a fire, intumescent form an insulating foam barrier, protecting the steel structure from the heat. (Clariant Produkte Deutschland GmbH - 2013).


Bottom: Intumescent coatings can foam to tens to hundreds of times its original thickness and the new VINNAPAS® LL 3112 binder ensures significant foam development coupled with improved adhesion and strength (photo: Clariant Produkte Deutschland GmbH - 2013).


insulating effect of the thermal shield would be extremely difficult to achieve because the shield would be too brittle and would not adhere securely enough to the metal substrate. “Fires are usually accompanied by severe air turbulence and vibrations. It is essential then that the foam layers do not spall away,” says Achim Hennemann, Key Account Manager, Intumescent Coatings at Clariant, a chemical company that produces the ammonium polyphosphate (Exolit®) that constitutes the main component of fire protection coatings.


BINDER CRITICAL Although the binder plays a supporting role in intumescent coatings, it is nonetheless crucial to their efficacy, as Hennemann knows: “The quality of the binder is the key to intumescent coatings. It determines the success or failure of a good recipe.” The binder determines how fast the layer of foam forms and its thickness around the steel columns. That’s why the experts from WACKER worked closely with their colleagues from Clariant as they were developing their new dispersions specifically for such applications – and success proved them right: The new dispersion VINNAPAS® LL 3112 generates foam in a much greater yield and with an even finer, denser pore structure. A corollary of this greater


efficiency is that a lower overall coating thickness is required than in conventional systems, without sacrificing any insulating effect. Thus, thanks to the new binder, fewer coats are needed. “Intumescent coatings often need up to seven coats – and just as many drying periods,” explains Clariant manager Hennemann. “So, thinner coats that deliver the same performance, i.e. fire resistance time, will save on material, time – and costs.” In VINNAPAS® LL 3112,


the WACKER experts have also succeeded in complying with the increasingly stringent sustainability requirements – the new binder contains neither plasticizers nor is it produced with alkylphenol ethoxylates-containing materials. A further plus for the environment is that the dispersion is not based on organic solvents but is water- borne. “And the market for water-borne fire protection


coatings has the potential to grow significantly in the next several years,” estimates Hennemann. Not only in the event of fire


must a binder fulfil its purpose. Coatings firms usually store fire protection coatings for long periods. “The viscosity must not change during the period in storage, i.e. the product must remain stable,” stresses WACKER expert Huster. “Thanks to our new binder, products will remain stable even when stored at elevated ambient temperatures.”


CRITERIA SATISFIED Nearly all countries specify that steel structures – whether they be all-glass, see-through exhibition halls or towering office blocks – must satisfy certain criteria governing the length of time they have to be able to resist fire. In Germany, “F 30” means that a load-bearing steel structure must be able to withstand a fire, i.e. heat, for at least 30 minutes under standard conditions. “The thinner the steel cross-section, the thicker the fireproof coating must be to achieve the required fire rating. Nowadays, intumescent formulations are capable of achieving an F rating of two hours and longer,” says Clariant’s Hennemann. Coatings formulations


with VINNAPAS® LL 3112 can reach top ratings here, too: Depending on the formulation, the new binder allows highly fire-resistant coatings with fire resistance class F120 to be achieved, which means heat protection for up to two hours. VINNAPAS® LL 3112 is just one example of WACKER helping to ensure that steel structures withstand fires for precious extra minutes that could save lives.


44 PCE APRIL-JUNE 2013


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