UOP L-PASTE

UOP L-Paste is a commercial molecular sieve product — a synthetic cuboidal zeolite (L-type/L-series, 4Å family) supplied as a 50% dispersion in castor oil — formulated as a moisture scavenger for solvent-free polyurethane systems, coatings, adhesives, elastomers and other water-sensitive formulations. 
This article reviews its composition and identifications, physicochemical properties, manufacturing and formulation considerations, mechanism of water adsorption and heat evolution, performance characteristics, typical applications, handling and safety, analytical and quality control methods, and alternatives and compatibility issues.
CAS number: 8001-79-4
Synonyms / related products: UOP L-Powder, UOP L-Powder ECO, UOP L-Paste ECO, UOP 4A/4Å molecular sieve products (similar function/use), T-Paste/T-Powder (related UOP family)
Chemical & Physical Description
Material class
UOP L-Paste is a molecular sieve (zeolite) — an aluminosilicate crystalline framework with uniform pores that selectively adsorb polar molecules, principally water.
The L series (also referenced as L/L-type) is functionally similar to 4Å zeolites used for water scavenging in liquid systems. Supplied as a dispersion/paste, the majority phase is the inorganic crystalline sieve dispersed in castor oil. 
 
Appearance and physical state
Cuboidal, crystalline particles (when isolated as powder); offered as a viscous paste (approx. 50% solids) in castor oil for improved handling and to prevent dust formation. 
Vendors describe tan/cream colored pastes or grey/tan powders depending on formulation. 
 
Typical composition (qualitative)
Zeolite (synthetic aluminosilicate) — primary active adsorbent.
Castor oil (RICINOLEIC ACID triglycerides) — carrier / dispersion medium (~50% of weight in pastes). CAS 8001-79-4 is associated with castor oil. 
 
Particle size and surface
Powder forms of UOP L are fine crystalline particles; the paste form maintains similar particle morphology but embedded in oil. 
Particle size distributions vary by product lot and influence kinetics of water uptake in liquid matrices (smaller particles = faster adsorption). 
Vendor datasheets may list median particle sizes for powder grades — consult specific lot documentation. 
Manufacturing & Formulation Notes
Zeolite synthesis (general for L/4Å)
The synthetic zeolite backbone is produced by hydrothermal synthesis from sodium-aluminosilicate gels under controlled temperature and alkali conditions to yield the L-type (A-type/4Å) crystalline framework. 
After crystallization, the sieve is washed, ion-exchanged (if required), dried and activated (to remove templating/adsorbed water) before formulation. 
UOP’s industrial supply chain includes multiple product formats (powder, paste, beads, pellets) depending on application. 
 
Paste production
To make the paste (UOP L-Paste), UOP or distributors uniformly disperse the activated crystalline powder into castor oil to ~50% solids. 
The carrier oil reduces dust, aids dosing into viscous polymer systems and moderates the intense heat release when the zeolite adsorbs water in concentrated events (though heat evolution still occurs). The paste must be mixed/homogenized to ensure consistent solids loading. 
 
Mechanism of Action — Water Adsorption & Heat Release
Zeolites capture water primarily by physisorption onto internal pore surfaces and by cation–dipole interactions at exchange sites within the aluminosilicate framework. 
Adsorption is exothermic — when previously dried/activated zeolite contacts free water (e.g., dissolved or emulsified moisture in a reactive polymer matrix), it can release heat as it rapidly adsorbs water molecules. 
Vendor SDSs frequently warn that the product can heat up spontaneously when wetted due to the exotherm of adsorption. 
This is an important safety and formulation consideration. 
 
Performance Characteristics
Water capacity and kinetics
Equilibrium capacity: depends on type (4Å vs other pore sizes), activation state, and humidity. 
Typical 4Å zeolites have high affinity for water at low relative humidities — making them effective scavengers in hydrophobic or solvent-free polymer matrices. 
The paste form reduces immediate surface exposure but provides convenience; effective capacity per gram of active solids is comparable to powder. 
Compatibility with polyurethane & coatings systems
Designed specifically for solvent-free one-pack and two-pack polyurethane systems to remove traces of water that would otherwise react with isocyanates (causing premature polyurethane formation, bubbling, defects). 
UOP L-Paste is widely used in coatings, adhesives, sealants and elastomers where moisture control is crucial. 
 
Effect on cure, rheology and finish
As a particulate filler, the paste will influence rheology (increasing viscosity) and may affect surface finish if not well dispersed; formulation labs typically trial progressively increasing loadings to balance moisture control vs. mechanical/property impacts. 
The castor oil carrier modestly plasticizes and aids dispersion. 
 
Typical Applications & Use Cases
Moisture scavenging in solvent-free polyurethanes (1K & 2K). 
Prevents isocyanate-water side reactions which cause CO₂ evolution, bubbling, and poor cure. 
Coatings, sealants & adhesives: used to protect moisture-sensitive chemistries during storage and curing. 
Plastics processing: as desiccant additive for moisture-sensitive formulations. 
Gas drying / industrial adsorbent applications: while L-Paste is formulated for liquid systems, UOP L powders and beads are used across gas and liquid purification markets — UOP product family is extensive and includes pellets, beads and powders for different processes.

SAFETY INFORMATION ABOUT UOP L-PASTE

 
 
 
 
 
First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product