Moisture absorbers for PU systems

Moisture absorbers for PU systems

Wednesday, 14 April, 2021

The use of moisture absorbers – molecular sieves, zeolites, etc. – is very commonplace given the sensitivity of many systems to moisture. Moisture can come from the raw materials themselves, as well as from the air or the substrate on which they are applied. At Comindex we recommend the Finma-Sorb range from FINMA to deal with this problem.

These products are molecular sieves, available in both powder and paste form, dispersed in castor oil. The advantage of the paste is its ease of use and dispersion and it is more effective and stable – the castor oil avoids direct contact of the active material with moisture in the air.

The pore size of the Finma-Sorb range is 3 Å, specifically for the absorption of water molecules. Other products on the market have a larger pore size which, although they could be thought of as more efficient, can result in defects. This is due to the absorption of other larger-sized molecules – such as nitrogen – and their possible release into our product under certain conditions, creating foaming problems or defects.

Their incorporation also prevents the generation of foam due to secondary reactions caused by the presence of moisture. An example is the formation of CO₂ from the reaction of the isocyanate and water or moisture contained in the raw materials.

Their use is recommended primarily for PU systems – 1- and 2-component systems, coatings, adhesives and sealants.

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

URL: https://finma.de/en/finma-gmbh-2

Subscription to eNews

Use your email address to subscribe to our newsletter and we will keep you up-to-date on the latest product developments, events and seminars.

Secondary menu