Sealing systems based on MS polymer or polyurethane
Both MSP and PU technologies are permanently elastic and have good bonding properties. They both react to moisture, forming a strong and flexible network. This makes these sealing technologies highly suitable for absorbing motion and vibration.
Movable joints can be sealed well with both technologies. MSP and PU sealants are also suitable in situations where materials with different thermal expansion coefficients need to be sealed. On this basis, therefore, both technologies can be applied for durable sealing of tanks or silos.
Although at first glance, MSP and PU sealants appear to have many similar properties, there are clear differences in the basis of the two technologies. For example, MSP contains reactive silane/silyl groups that provide for the curing. PU systems contain reactive isocyanate groups for curing.
Silane versus isocyanate
The curing reaction based on silane (MSP system) has fewer or no undesirable secondary reactions under the influence of moisture. This is in contrast to material containing isocyanate (PU system), which will foam or blister in a moist environment. This is because carbon dioxide is released during curing, which leads to deterioration in the properties of the material. Another disadvantage of PU sealants is that contact with isocyanates is possible during application, particularly during the finishing process: these chemicals constitute a health risk. In short, a label-free MSP is safer during application. This sealant can also be applied in less favorable (moist) conditions.