"Methyltris(methylisobutylketoxime)silane (CAS 37859-57-7) is a slow-release oxime crosslinker offering extended open time and improved weathering resistance in neutral-cure silicone formulations."
-Deshangchemical-chemechemi
Methyltris(methylisobutylketoxime)silane (CAS 37859-57-7), also known as methyl-tris(methylisobutylketoxime)silane or MIBK-oxime silane, is a specialized trifunctional Methyltris crosslinker designed for demanding neutral-cure silicone applications. With molecular formula C₁₉H₃₉N₃O₃Si and molecular weight 385.62 g/mol, it offers distinct advantages over the more common MEK-oxime version (CAS 22984-54-9) in specific formulation scenarios.
Chemical Profile
CAS Number: 37859-57-7
Molecular Formula: C₁₉H₃₉N₃O₃Si
Molecular Weight: 385.62 g/mol
Appearance: Light yellow to yellow liquid
Flash Point: ~120°C (significantly higher than MEK-oxime analog)
Purity: ≥95%
Key Differentiator: Extended Open Time
The methylisobutylketoxime leaving group in this Methyltris compound hydrolyzes more slowly than methylethylketoxime, resulting in a significantly extended open time — the window during which the sealant remains workable after application. This is critical for:
Large facade glazing projects where joints need repositioning
Automated dispensing systems with variable shot times
High-performance structural glazing applications
Tropical climates where fast surface skin-over is a problem
Performance Comparison: CAS 37859-57-7 vs CAS 22984-54-9
While both are Methyltris oxime-type crosslinkers, their performance profiles differ:
Tack-free time: Longer for MIBK-oxime (CAS 37859-57-7) — beneficial for open-time control
Full cure depth: Similar bulk cure rates at equal catalyst levels
Thermal stability: Higher for MIBK-oxime due to larger leaving group
MEKO content: Zero — important for products requiring MEKO-free formulations
Applications
Structural Silicone Glazing (SSG)
Structural silicone glazing systems require silicone sealants with precise open-time windows to allow proper joint tooling and substrate alignment. CAS 37859-57-7 delivers the controlled work life that SSG applications demand.
Industrial Maintenance Coatings
Industrial silicone coatings applied in large-area spray or roll-coat operations benefit from the extended pot life provided by this Methyltris silane crosslinker.
MEKO-Free Neutral Cure Formulations
In regions where methyl ethyl ketoxime (MEKO) faces regulatory restrictions, formulators substitute CAS 37859-57-7 to maintain neutral-cure chemistry while achieving full regulatory compliance.
Formulation Considerations
Loading levels are typically 4–10 phr in RTV silicone bases. Compatible with most organotin and organotitanate catalysts. Platinum-catalyzed addition-cure systems are incompatible with this crosslinker type.
Pre-mix compatibility testing is recommended when blending with CAS 22984-54-9 to achieve customized open-time profiles.
Purchase Methyltris(methylisobutylketoxime)silane
Deshang Chemical maintains inventory of CAS 37859-57-7 for immediate delivery to sealant manufacturers worldwide. We offer technical consultation on crosslinker selection and formulation optimization. Inquire about pricing for 25 kg, 180 kg, and IBC tote quantities.
