Moisture scavenger for reduced defects in polyurethanes

Polyurethanes are created by reacting a polyol with an isocyanate or a polymeric isocyanate. These coatings are attractive to customers as they enhance durability and energy efficiency in a variety of applications. However, one common issue that arises is moisture absorption by isocyanates in the coating, which can release carbon dioxide (CO2) bubbles. This can result in paint defects such as gloss reduction, haze formation, and foam generation.

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Considering these moisture-related defects, it becomes evident that storage stability is crucial for polyurethane coatings, adhesives, and sealants. Varied conditions such as hot and humid environments, along with precipitation, contribute to increased moisture levels. In addition, improper storage of polyurethane paints exacerbates moisture accumulation in coatings. Utilizing moisture scavengers emerges as an effective strategy to enhance storage stability and mitigate paint defects.

Strategies to Prevent Moisture-Related Defects

A moisture scavenger for polyurethane systems, exemplified by Additive TITM or Additive OF, is a premium additive engineered to eliminate moisture through various chemical mechanisms. These wholly active additives feature low viscosity and effectively withdraw undesirable moisture from solvents, fillers, and pigments. Moreover, they provide extended stability for both solvent-based 1k and 2k polyurethane paints, sealants, adhesives, coatings, and casting compounds after exposure to humid conditions.

Both Additive TITM and Additive OF work effectively to reduce the effects of side reactions during storage, which can result in CO2 generation and polyurea formation (gelling effects) in polyisocyanate systems. Additionally, moisture scavenger additives minimize surface imperfections (such as foam, haze, and low gloss) in the resulting film.

Additive TITM: An Effective Moisture Scavenger for Short-Term Dehydration

Additive TITM excels at providing excellent short-term dehydration. This moisture scavenger outperforms other drying methods based on molecular sieves (zeolites) and delivers rapid dehydration. Being colorless, Additive TITM doesn’t lead to cloudiness or color problems in polyurethanes and can be seamlessly integrated during the production phase.

Without moisture scavenger                                                                                             With Additive TITM

Reduced defects in a PU coating

Additive OF: A Convenient Moisture Scavenger for Long-Term Dehydration

Additive OF proves to be an ideal long-term dehydration solution, serving primarily as a package stabilizer. Similar to Additive TITM, this moisture scavenger offers advantages over other dehydration techniques utilizing molecular sieves (zeolites). Rather than merely adsorbing water molecules, this additive chemically transforms them in the coating.

Additive OF is also a colorless liquid, ensuring it doesn’t introduce cloudiness or discoloration in polyurethane finishes. Its reactions and by-products are more sustainable compared to other reactive moisture scavengers. This solution can be applied to both hydroxyl and isocyanate components, and is also versatile enough for use during production.

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Applications for Moisture Scavengers

Additive TITM and OF effectively dehydrate pigments and fillers in numerous applications. Initially, pigments must be blended in a solvent together with the measured amount of moisture scavenger(s), which can significantly differ based on moisture content.

Achieving complete dehydration may take up to 24 hours. Upon completion, this mixture can be combined with polyol (OF only) or isocyanate (TI and OF) components.

Moisture-Cured One-Component Polyurethane Systems

Additive TITM and OF offer utility as storage stabilizers, effectively reducing premature curing in packaging (casks). They may be used independently or in tandem to optimize results.

Prepolymer Systems

Using Additive TITM in catalyzed prepolymer systems hinges on the type of catalyst utilized. Unique amine-based catalysts can enhance the interaction between p-toluene sulfonamide and isocyanate prepolymer, subsequently affecting NCO/OH ratios and possibly leading to incomplete cross-linking reactions.

Conclusion

Additive TITM and OF both serve as potent moisture scavenger solutions. These additives efficiently dehydrate pigments, fillers, and solvents within moisture-sensitive 1k and 2k polyurethane coatings, reducing the risk of defects such as gloss reduction, haze formation, and foam generation.

Additive TITM is a remarkable choice for fast-acting short-term dehydration, while Additive OF is the ideal package stabilizer for long-term dehydration.

Please visit our moisture scavenger product page for technical data sheets and further details regarding these products.

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