Name: Molecular Sieve 3Å Desiccant Paste for Sealants
Brand: Coatingsink
SKU: molecular-sieve-3a-sealant
Availability: InStock

Question 1

What is the recommended dosage of molecular sieve paste in a two-component PU sealant?

Accepted Answer

Typical dosage is 3–8 phr in the isocyanate-containing component. Higher loadings up to 10 phr are used for aggressive moisture environments or extended shelf-life targets. Add under low-shear mixing to avoid crushing the sieve crystals and reducing adsorption capacity.

Question 2

Why use a pre-dispersed paste rather than powder molecular sieve in sealant formulations?

Accepted Answer

Powder molecular sieve is strongly hygroscopic and prone to agglomeration during mixing. The 50%-active paste in polymer carrier integrates directly into the resin phase, eliminates dust hazards, and ensures homogeneous distribution for consistent moisture scavenging throughout the sealant bead.

Question 3

Does the 3Å pore size selectively adsorb water without affecting organic formulation components?

Accepted Answer

Yes. The 3Å pore diameter admits water molecules (kinetic diameter ~2.65 Å) but excludes most plasticizers, solvents, and polymer segments (>4 Å). This selectivity makes it ideal for MS polymer and moisture-curing PU systems where inadvertent adsorption of formulation components would degrade final mechanical properties.

Pore Diameter	3 Å
Particle Size D50	≤5 µm
Active Sieve Content	50%
Paste Viscosity (25°C)	30,000–60,000 mPa·s
Moisture Adsorption Capacity	≥20% (on active sieve)

Molecular Sieve 3Å Desiccant Paste for Sealants

Specifications

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