Product Description of Silane Coupling Agent - Si75
Silane Coupling Agent Si75, chemical name Bis[3-(triethoxysilyl)propyl] disulfide (TESPD), is a disulfide-type sulfur-containing silane coupling agent and a key additive for green tire industry. Its molecular structure consists of triethoxysilyl groups on both ends and a stable disulfide linkage in the middle. During rubber mixing, ethoxy groups hydrolyze and react with hydroxyl groups on silica surface to improve silica dispersion in rubber matrix. In vulcanization process, disulfide bonds break and bond with rubber macromolecules, building chemical bridges between inorganic filler and rubber, so as to greatly enhance physical properties of rubber compounds. Compared with tetrasulfide silane Si69, Si75 provides wider processing window and superior scorch resistance. It is the preferred modifier for silica-reinforced rubber systems.
Product Parameters
|
Appearance |
Light yellow transparent liquid |
|
Effective Component |
≥95.0% |
|
Density (25℃) |
1.06–1.09 g/cm³ |
|
Refractive Index |
1.455–1.470 |
|
Sulfur Content |
12.5–13.5% |
|
Moisture |
≤0.5% |
Application
1. Green Tires: Passenger car tire & light truck tire tread compounds. Reduce tire rolling resistance and improve wet grip. Resist high temperature mixing and avoid scorch, suitable for high-speed continuous production lines.
2. Technical Rubber Goods: Rubber vibration dampers, conveyor belts, rubber hoses, rubber soles and seals. Improve filler dispersion, boost tensile strength & abrasion resistance, reduce compression set.
3.Other Modification Fields: Surface modification of inorganic fillers such as silica, clay and mica; glass fiber composite materials, improve compatibility between inorganic fillers and polymers.
Product Advantages
1. Excellent Scorch Resistance & Wide Processing Window: It features good thermal stability and resists premature decomposition during high-temperature mixing. The stable disulfide bond greatly lowers the risk of scorch failure, allowing higher mixing temperatures and matching high-efficiency internal mixer production lines.
2. Improve Silica Dispersion & Reduce Compound Mooney Viscosity: It can build chemical bridges between inorganic fillers and rubber molecules, enabling more uniform dispersion of silica. It significantly reduces the Mooney viscosity of the rubber compound, improves processing fluidity, cuts mixing energy consumption, and limits viscosity rise during storage for better compound stability.
3. Optimize Dynamic & Mechanical Performance of Rubber: It reduces rolling resistance and improves abrasion resistance and tear resistance of rubber products. The finished material delivers lower heat build-up, higher modulus and smaller compression set. It also stabilizes extrusion and calendering processes and achieves a finer surface appearance of final products.
4. Good Formula & Vulcanization System Compatibility: It has high compatibility with most diene rubber systems and works harmoniously with the vulcanization system without interfering with normal vulcanization, ensuring consistent batch quality.
Services
Supplied in standard sealed 25kg plastic drums. Small sample packages are available upon request. We maintain stable inventory and offer fast lead times. Quality inspection certificates can be provided. Our team supports formula optimization, and technical specialists are available to guide on practical operation parameters including feeding sequence and mixing temperature.
FAQ
1. What is the core difference between Si75 and Si69 in practical mixing and vulcanization?
Si75 is a disulfide silane while Si69 is tetrasulfide silane. Si75 owns better thermal stability and will not decompose prematurely under high-temperature mixing, which effectively prevents scorch and supports a wider processing window. However, Si75 carries less sulfur in its molecular structure. When replacing Si69, you generally need to add an extra 0.3–0.5 phr elemental sulfur to the formula to compensate for sulfur contribution. Si69 delivers stronger cross-linking contribution but carries higher scorch risk at elevated mixing temperature.
2. How will Si75 affect Mooney viscosity, extrusion and calendering performance of silica-filled rubber compounds?
Si75 builds chemical bridges between silica and rubber molecules, achieving uniform silica dispersion and significantly reducing Mooney viscosity of the compound. Improved fluidity stabilizes extrusion and calendering processes, reduces surface defects, and delivers a finer finished product appearance. Meanwhile, it limits viscosity rise during compound storage and improves stock stability.
3. What storage conditions are required for Si75? What risk will be caused by moisture exposure?
Store Si75 in sealed original drums in cool, dry and ventilated warehouse, away from heat and oxidants. Si75 is moisture-sensitive. Once exposed to water or humid air, hydrolysis reaction occurs, which destroys the silane functional group and permanently weakens coupling efficiency. Unsealed drums should be consumed as soon as possible. The shelf life is 12 months under proper sealed storage.
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