31/03/2020
The importance of correct product specification has never been more important, and the implications of even the smallest change can have huge implication. So whilst it might seem an insignificant detail in the construction or refurbishment of a building or structure, the performance of sealants should not be underestimated. Playing a crucial role in the performance of a building throughout its lifetime, but with only a small fraction of the total construction cost, what is the chemistry behind these polyurethane-based sealants to ensure they are flexible, stable and durable under any environmental and load conditions?
When a failure occurs in a sealant joint, it will threaten the longevity of a building’s exterior. Joints and openings between construction elements can be found in different parts of a construction, whether it is between pre-cast concrete elements in façades, around windows and doors, at the connection between floors and walls or in storage tanks.
Depending on the function and location of the respective joint, a joint sealant will prevent passage of media such as air, water, chemicals and smoke, provide thermal and sound insulation, and enhance the visual appearance of the whole construction.
In order to ensure effective sealant and protective coatings formulation, and exceptional bubble-free curing, Aldirez BH is an Aldimine latent curing agent that provides moisture triggered technology which enables water and weatherproof compounds to be developed and used inside and outside.
Simply by taking moisture out of the equation, Aldirez BH is the ideal solution for defect-free, high-build polyurethane systems.
Bubble-free performance
One of the challenges with PU-based sealants is that they can offer poor storage stability and bubbling due to the evolution of CO2. This leads to sealants evidencing poor durability and delamination from the concrete substrate.
In a traditional moisture cure reaction, moisture reacts directly with the terminal isocyanate of the pre-polymer, generating carbon dioxide. The use of Incorez’s Aldirez BH latent curing agent avoids the generation of carbon
dioxide, thus enabling bubble free curing at elevated temperatures and humidity levels. Shelf life is also vastly improved while storage and low crystalline stability is excellent.
Another challenge with PU sealants is flexibility to allow for the extension and contraction of the sealants due to environmental conditions. It’s critical for the sealant to have the right amount of flexibility to withstand cold and hot temperature extremes. Aldirez BH does just that. It provides that flexibility and ensures a low-to-medium modulus sealant will be able to take significant movement without applying stress on the sealant itself or the substrate.
