Siwin-9031
Siwin
Siwin-9031
5575-48-4
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3-Mercaptopropylmethyldimethoxysilane (Siwin-S121) is a bifunctional organosilane compound containing a reactive mercapto group (-SH) and two hydrolyzable methoxy groups (-OCH3) bonded to a silicon atom. The mercapto group reacts with organic polymers and metal surfaces, while the methoxy groups hydrolyze to form silanol groups that establish bonds with inorganic substrates. This dual reactivity positions the compound as a cross-linking agent and surface modifier across industrial applications. The molecular formula is C6H16O2SSi with a molecular weight of 180.34 g/mol.
Unlike trimethoxy-type mercapto silanes, Siwin-S121 carries a methyl group directly bonded to the silicon atom. This structural variation affects hydrolysis kinetics and cross-linking density in cured systems. With a minimum purity specification of 98.0% measured by gas chromatography, the compound delivers consistent batch-to-batch performance for formulated products. The product corresponds to industry reference model KBM-802 and carries the Siwin product code Siwin-S121.
Momentive | Dowcorning | ShinEtsu | Evonik | Wacker |
|---|---|---|---|---|
N.A | N.A | KBM-3103 | N.A | N.A |
Property | Value |
|---|---|
Appearance | Colorless clear liquid |
CAS NO. | 31001-77-1 |
Purity | ≥98.0% |
Formula | C6H16O2SSi |
Molecular Weight | 180.34 |
Density | 1.00 |
Boiling point | 96 ºC (30 mmHg) |
Flash point | 93 ºC |
Refractive index | 1.45 |
Chemical Structure |  |
The primary application of mercaptopropylmethyldimethoxysilane is as a cross-linker for one-pack room temperature vulcanizing (RTV) silicone rubber. In deoxime-type and dealcohol-type RTV systems, the mercapto functional group participates in the curing mechanism, contributing to the formation of a three-dimensional siloxane network. The methyl substitution on silicon provides a balanced cure rate suitable for sealant and adhesive formulations used in construction, automotive assembly, and electronic encapsulation.
Siwin-S121 serves as a surface treatment agent for inorganic fillers such as silica, calcium carbonate, and glass fibers. The methoxy groups react with hydroxyl groups on filler surfaces, while the mercapto group provides compatibility with sulfur-cured rubber systems and polar polymers. This surface modification improves filler dispersion in polymer matrices, reduces viscosity of filled compounds, and enhances mechanical properties of the final cured product.
The compound functions as a raw material intermediate in the production of specialty silicone oils and mercapto-functional silicone polymers. Through equilibration or condensation reactions, the mercapto group can be incorporated into polysiloxane chains, imparting thiol functionality for subsequent modification or cross-linking reactions.
Production of Siwin-S121 follows established organosilane synthesis processes with batch-level quality verification. Each production lot undergoes gas chromatography analysis to confirm purity meets the ≥98.0% specification. Physical property testing including density, refractive index, and appearance inspection is performed according to standardized test methods. Certificates of Analysis (COA) are available upon request for each shipment.
The product falls under HS code 2931900090. As a flammable liquid with skin and eye irritation potential, standard industrial handling procedures apply. Safety Data Sheets (SDS) detailing hazard classification, handling precautions, and emergency measures are available for commercial users. The product is manufactured under ISO 9001-certified quality management systems.
Siwin-S121 is available in 200L PVF steel drums as the standard packaging configuration, with custom packaging options available for enterprise customers. The product requires storage in a cool, dry location protected from direct sunlight and moisture ingress. Under proper storage conditions, the product maintains its specified properties for the duration of the shelf life. For bulk orders or custom packaging requirements, business buyers are encouraged to contact the technical sales team for detailed specifications.
It functions as a cross-linking agent that participates in the moisture-induced curing reaction. The methoxy groups hydrolyze upon exposure to atmospheric moisture, forming silanol groups that condense to build the cured silicone network, while the mercapto group contributes to adhesion and cross-link density control.
The methoxy groups react with surface hydroxyls on inorganic fillers, creating a hydrophobic organic coating that improves wetting by polymer matrices. This reduces compound viscosity, enhances filler loading capacity, and improves mechanical properties of the finished product.
The product should be stored in a cool, dry, well-ventilated area away from direct sunlight and sources of ignition. Containers must be kept tightly sealed to prevent moisture ingress and hydrolysis. Recommended storage temperature ranges from 5°C to 30°C.
Typical addition levels range from 2% to 5% by weight of the total formulation, depending on the specific RTV system, desired cure speed, and required mechanical properties. Formulators should conduct laboratory trials to determine optimal loading for each application.
Yes, it can be used in combination with other functional silanes such as amino silanes or epoxy silanes to achieve balanced properties. Compatibility and performance should be evaluated through formulation testing for each specific system.
