Discover how molecular sieves help reduce moisture-related defects and helps support formulation stability in polyurethane coatings, adhesives, sealants and elastomers.
Moisture Control Challenges in Polyurethane CASE Formulations
Beyond visible defects, moisture contamination can affect formulation stability, shorten shelf life, alter viscosity and create variability during manufacturing and application. Controlling trace moisture is therefore an important consideration to help maintain product performance depending on formulation and processing conditions.
Molecular sieves offer an effective solution for removing trace water from moisture-sensitive polyurethane formulations. Unlike reactive moisture scavengers that become part of the chemistry, molecular sieves selectively adsorb water through a physical adsorption mechanism, helping protect formulation integrity while supporting performance in moisture-sensitive polyurethane systems.
Key Benefits of Using A Molecular Sieve for Moisture Control
A molecular sieve for moisture control can help formulators to:
- Reduce blistering, bubbling and moisture-related surface defects and curing issues
- Support improving storage stability in moisture-sensitive systems, shelf life and processing consistency by maintaining predictable viscosity and product quality
- Helps maintain formulation stability, process consistency and product performance depending on formulation and processing conditions
Molecular Sieves for Polyurethane Formulations
Honeywell Technologies UOP MOLSIV™ and UOP L and T adsorbent ranges are designed to selectively remove moisture from moisture-sensitive polyurethane formulations.
- Selective moisture removal: UOP MOLSIV™ Type A molecular sieve technology selectively adsorbs water molecules while leaving larger formulation components unaffected.
- Reduced risk of moisture-related defects: By removing trace moisture, molecular sieves help minimise the risk of blistering, foaming, curing inconsistencies and other moisture-related formulation challenges.
- Rapid adsorption performance: Fine particle size and porous crystal structures support rapid contact with moisture within formulations.
- Pot-life stability: Lower alkalinity in UOP L and T products may help support pot-life stability compared with conventional activated powders.
- Flexible incorporation options: Available as activated powders and as castor oil-based pastes to support easier dispersion into formulations.
Coatings, Adhesives, Sealants, Elastomers and Flooring Applications for Molecular Sieves
The Honeywell Technologies molecular sieves portfolio brings benefits to the following applications:
- Polyurethane coatings: Helps reduce moisture-related defects such as blistering, bubbling and cure inconsistencies while supporting coating performance and storage stability.
- Polyurethane adhesives: Supports moisture control in adhesive systems where trace water can negatively affect processing, application behaviour and final bond performance.
- Polyurethane Sealants: Removes residual moisture while maintaining compatibility with moisture-sensitive sealant formulations.
- Polyurethane Elastomers: Helps manage residual water in polyurethane elastomer systems during production and storage.
- Industrial flooring systems: Supports moisture control in polyurethane and polyaspartic flooring systems where residual water can affect processing, appearance and final performance.
- Metal-rich coatings: 4A-AP is used as a water scavenger in zinc and aluminium-containing coatings where moisture can affect product stability.
UOP L and T Grades: Purpose-designed Molecular Sieves for CASE Formulations
Honeywell Technologies' L and T products are particularly suited for applications requiring enhanced pot-life stability and lower alkalinity compared with conventional activated powders. Available in powder and castor oil-based paste formats, these Type A molecular sieves combine high moisture adsorption capacity, rapid adsorption rates and lower alkalinity than conventional activated molecular sieves.
The fine particle size supports efficient dispersion within formulations, while paste grades simplify handling and incorporation into liquid systems. The result is effective moisture control that helps support formulation stability and processing consistency across a wide range of CASE applications.
Molecular Sieve Product Grades and Technical Specifications
Honeywell Technologies' portfolio of molecular sieves includes grades designed for a wide range of polyurethane coatings, adhesives, sealants, elastomers and industrial flooring systems, including polyaspartic flooring. Depending on formulation requirements, products are available with either a 3A molecular sieve or 4A molecular sieve pore structure: 3A molecular sieve grades offer more selective moisture removal with lower alkalinity, while 4A molecular sieve grades provide broader moisture adsorption capacity for general-purpose formulation stability. Available in both powder and paste formats, the products offer different pore sizes, moisture adsorption capacities and formulation characteristics to support specific moisture control requirements. The table below provides an overview of the available grades and their typical application areas.
| Grade | Format | Pore diameter (Å) | Water adsorption capacity (wt%) | Typical use case |
|---|---|---|---|---|
| UOP L Powder | Powder | 3 | 24 | Extended pot-life stability and moisture control in sensitive formulations requiring lower alkalinity. |
| UOP L Paste | Paste | 3 | 11* | Extended pot-life stability and moisture control where a paste format improves incorporation and dispersion. |
| UOP T Powder | Powder | 4 | 24 | Extended pot-life stability with broader adsorption capability for moisture-sensitive formulations. |
| UOP T Paste | Paste | 4 | 11* | Extended pot-life stability in a paste format for easier handling and incorporation. |
| MOLSIV™ 3A-AP | Powder | 3 | 25.5 | Selective moisture removal when moisture is the primary cause of gassing, foaming, pressure build-up, premature curing, or shelf-life instability. |
| MOLSIV™ 4A-AP | Powder | 4 | 27 | Moisture control plus CO₂/off-gas management where broader contaminant control is desired. |
| MOLSIV™ 5A-AP | Powder | 5 | 26 | Moisture-sensitive formulations where lower alkalinity and minimal formulation impact are priorities. |
| MOLSIV™ 13X-AP | Powder | 8.5 | 34 | Moisture, VOC, odor, and off-gas control where broader adsorption is required beyond water alone. |
* Water adsorption capacity for paste grades is reported for the supplied paste form. UOP L and T pastes contain approximately 50% active zeolite dispersed in castor oil.
Packaging note: UOP L and T grades are available as powders and pastes, while MOLSIV® grades are available in a range of packaging formats including drums, bags and supersacks, depending on grade.
Trial Molecular Sieve for Moisture Control in Your Formulation
Interested in reducing blistering, bubbling, curing inconsistencies or other moisture-related defects in your formulation?
Request a sample and discuss your application requirements with our technical experts. We can help identify the most suitable molecular sieve grade for your coating, adhesive, sealant or elastomer formulation.
Product performance depends on formulation chemistry, moisture load, processing conditions, dosage level and application requirements. Customers should evaluate product suitability and performance within their specific formulation and process conditions.