A-LINK25; KBE-9007
Momentive ; ShinEtsu
2931900090
Siwin-AL32
24801-88-5
| Quantity: | |
|---|---|
3-Isocyanatopropyltriethoxysilane, designated Siwin-AL32 with CAS number 24801-88-5, is a bifunctional silane coupling agent featuring an isocyanate (-NCO) group and triethoxysilyl functionality. This product serves primarily as a crosslinker and adhesion promoter in moisture-curable adhesive, sealant, and coating systems, particularly modified silane (MS) polymer and polyurethane formulations.
The isocyanate group reacts with active hydrogen-containing functional groups including hydroxyls, amines, and thiols present in organic polymers, while the triethoxysilyl group hydrolyzes in the presence of atmospheric moisture to form siloxane bonds with inorganic substrates. This dual reactivity makes the product valuable for formulators developing single-component moisture-curable systems where crosslinking and substrate adhesion must occur simultaneously.
The following original specification table is preserved from the product documentation without modification to data values, structure, or formatting:
Property | Value |
|---|---|
Product No. | Siwin-AL32 |
Chemical Name: | 3-Isocyanatopropyltriethoxysilane |
CAS NO. | 24801-88-5 |
Formula | C10H21NO4Si |
Appearance | Clolorless to yellowish clear liquid. |
Density (ρ20°C,g/cm3) | 0.996 |
Refractive Index () | 1.420 |
Molecular Weight: | 247.36 |
Boiling Point: | 283 oC |
Purity (by GC, %) | ≥98% |
Chemical structure |  |
Additional verified specifications for reference:
EINECS Number: 246-467-6
Refractive Index: n20/D 1.420
Flash Point: 77 °C (closed cup)
Viscosity: 1.6 mm²/s (20°C)
HS Code: 2931900090
Purity is confirmed by gas chromatography with a minimum specification of 98 percent. Each production batch undergoes full physical property testing against the published specification before release.
The molecule structure of 3-isocyanatopropyltriethoxysilane consists of a three-carbon propyl chain linking an isocyanate functional group (-N=C=O) at one end to a triethoxysilyl group at the other. The molecular formula C10H21NO4Si corresponds to a molecular weight of 247.36 grams per mole.
The isocyanate group undergoes nucleophilic addition reactions with active hydrogen compounds. In polyurethane and MS polymer systems, the -NCO group reacts with hydroxyl-terminated polyether or polyester chains to form urethane linkages, effectively incorporating the silane functionality into the polymer backbone. This silane-terminated polymer then cures via moisture-induced siloxane crosslinking.
The triethoxysilyl groups hydrolyze upon exposure to atmospheric moisture, generating silanol intermediates. These silanols subsequently condense with one another to form siloxane (Si-O-Si) bonds, building a three-dimensional crosslinked network. This moisture-driven curing process proceeds at room temperature and does not require additional heat or catalysts, though organotin or amine catalysts may be used to accelerate cure speed.
At the substrate interface, hydrolyzed silanol groups form hydrogen bonds and eventual covalent siloxane linkages with hydroxyl groups present on glass, metal, concrete, and other mineral surfaces. This mechanism provides the adhesion promotion effect that is critical to sealant and adhesive performance in building and construction applications.
In single-component moisture-curable polyurethane adhesive formulations, the isocyanato silane functions as a crosslinking agent that simultaneously modifies polymer chain ends and introduces silane cure functionality. Adhesives formulated with this crosslinker exhibit rapid green strength development and good final bond strength, with cure progressing from the exposed surface inward as moisture diffuses through the material.
Modified silane (MS) polymer sealant manufacturers incorporate isocyanatopropyltriethoxysilane into their formulations to enhance adhesion to a broad range of substrates. The silane improves bond durability to glass, aluminum, steel, concrete, and various plastics, reducing the need for separate primer application in many construction and glazing scenarios.
In two-component polyurethane systems, the isocyanato silane can be added to either the polyol side or the isocyanate side of the formulation, depending on the desired reaction sequence. In two-part systems, the silane primarily contributes to improved substrate adhesion and enhanced resistance to humid aging of the bond line.
The product also serves as an adhesion promoter in silicone sealant and coating formulations where enhanced bonding to organic substrates bearing active hydrogen groups is required. The isocyanate group reacts with functional groups on the organic substrate surface while the silane portion integrates into the silicone matrix, creating a durable chemical bridge across the material interface.
In electronic encapsulation applications, the silane contributes to improved adhesion between potting compounds and component surfaces, including metal leads, ceramic substrates, and printed circuit boards. The enhanced interfacial bonding helps maintain electrical insulation properties under thermal cycling and humidity exposure conditions.
Formulations incorporating isocyanatopropyltriethoxysilane demonstrate measurable improvements in wet adhesion compared to unmodified systems. After immersion in water or exposure to high humidity environments, silane-modified adhesives and sealants retain a higher percentage of their dry-state lap shear and peel strength values on glass and metal substrates.
Sealants and coatings formulated with the isocyanato silane exhibit good resistance to thermal aging and UV exposure. The siloxane crosslink network contributes to retention of elasticity and adhesion properties after extended outdoor weathering, supporting the product's use in exterior construction and glazing applications.
The crosslinked siloxane-urethane hybrid network provides resistance to a range of chemicals commonly encountered in building and industrial environments, including dilute acids and bases, cleaning agents, and atmospheric pollutants. Specific resistance profiles depend on overall formulation composition and polymer selection.
When properly formulated with appropriate moisture exclusion and stabilizer packages, one-part systems containing the isocyanato silane maintain acceptable shelf stability for standard commercial product lifetimes. Formulators typically optimize moisture scavenger levels and packaging to achieve target shelf life specifications.
The product is supplied in 200L PVF-lined steel drums as standard packaging for industrial applications. Alternative packaging configurations, including smaller containers for formulation development and bulk tank truck options for high-volume enterprise customers, can be arranged upon request.
Store the product in a cool, dry, well-ventilated area away from direct sunlight and sources of moisture. Containers must be kept tightly sealed when not in use, as both the isocyanate group and the triethoxysilyl group are moisture-sensitive. Exposure to atmospheric moisture can cause gradual viscosity increase and gel formation through crosslinking reactions. Recommended storage temperature is between 2°C and 8°C for extended shelf life.
The isocyanate functional group is a known skin and respiratory sensitizer. Handling requires appropriate personal protective equipment including chemical-resistant gloves, safety glasses, and respiratory protection where vapor exposure is possible. Work areas should have adequate ventilation. Complete safety information, including exposure limits and first aid measures, is available in the Safety Data Sheet.
Typical loading levels range from 0.5 percent to 3.0 percent by weight of the total formulation. The optimal addition rate depends on polymer type, filler loading, substrate variety, and desired cure speed. Formulators usually conduct adhesion screening trials across the target substrate range to determine the minimum effective dosage.
Aminosilanes generally provide stronger initial adhesion to a wider range of substrates but can cause yellowing in certain polymer systems and may accelerate cure rates undesirably. Isocyanatosilanes offer good adhesion with lower impact on system color stability and more controllable cure kinetics, making them preferred in many MS polymer and light-stable polyurethane formulations.
Yes, the product can be formulated into a primer solution for application to substrate surfaces prior to sealant or adhesive installation. Primer solutions typically contain the silane diluted in an appropriate solvent, applied in a thin film and allowed to flash off before bonding. This approach is used when in-formulation addition does not provide sufficient adhesion on difficult substrates.
When stored in unopened original containers under recommended cool and dry conditions, the product maintains specification compliance for a minimum of 12 months from the date of manufacture. Storage at lower temperatures within the recommended range can further extend usable life.
Each shipment includes a Certificate of Analysis detailing batch-specific test results for purity, appearance, density, refractive index, and other specification parameters. Safety Data Sheets (SDS) are provided with initial orders and upon request. Additional documentation including REACH registration status and customs paperwork is available for international commercial procurement.
