How to prevent moisture damage in your PU systems

How to prevent moisture damage in your PU systems

Friday, 13 January, 2023

Moisture – which can come from various sources such as raw materials, air or the substrate of the application – can seriously damage PU systems due to their high sensitivity to water.

Therefore, the search for additives that prevent moisture contact with the system is of utmost importance for these applications.

A very common solution for absorbing moisture in raw materials involved in the formulation of coatings (fillers, pigments, solvents…) is the use of moisture absorbers (molecular sieves, zeolites…).

Which moisture absorber is distributed by Comindex?

FINMA-SORB, from our represented company FINMA, is a molecular sieve in powder or paste form, dispersed in castor oil. The latter format has different advantages:

  • Ease of use and dispersion
  • Higher effectiveness and stability: the castor oil acts as a barrier, avoiding direct contact between the active material and moisture

We recommend FINMA-SORB particularly for 1K and 2K PU systems, coatings, adhesives and sealants.

How does FINMA-SORB act to protect your formulations from moisture?

Thanks to a pore size of 3 Å, absorption of the water molecule is specifically targeted. Furthermore, although logical reasoning would lead us to believe that a larger pore size would make the sequestrant more efficient, this is not the case. This is because it would absorb not only water molecules, but also others of a larger size, such as nitrogen. In addition to a reduction of absorption capacity as other molecules and water enter into competition, absorption of other molecules may result in defects or foaming problems when they are released, for example, when the temperature of the system is slightly increased.

FINMA-SORB prevents the isocyanate from being consumed by reacting with water and also prevents generation of foam, carbon dioxide arising from this secondary reaction between moisture and the isocyanate.

For further information about these products, please contact our technical advisory team.


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