- ▸ Coupling agent: Bonds silica and mineral fillers to rubber and polymer matrices.
- ▸ Adhesion promoter: Improves filler-to-polymer coupling in compounds.
- ▸ Processing aid: Functions as a processing aid in rubber compounding.
- ▸ Binder: Links inorganic filler into the organic polymer network.
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
Request SDS →Bis[3-(triethoxysilyl)propyl] tetrasulfide (CAS 40372-72-3) is a sulfur-functional organosilicon coupling agent. It is used as an adhesion/cohesion promoter and processing aid, and it acts as a binder linking inorganic fillers to organic polymer matrices. The tetrasulfide bridge and triethoxysilyl groups let it bond silica to rubber networks.
Frequently Asked Questions
What does "bis" mean in this silane's name?
In chemistry "bis" means two of the named group. Here it denotes two 3-(triethoxysilyl)propyl groups joined by a tetrasulfide bridge, the structure of CAS 40372-72-3 (C18H42O6S4Si2).
What is bis-(3-triethoxysilylpropyl) tetrasulfide (Si-69, TESPT) used for?
It is a sulfur-functional organosilicon coupling agent and binder. The triethoxysilyl groups bond to silica and mineral fillers while the tetrasulfide bridge links into the rubber network, so it serves as a coupling agent, adhesion promoter, and processing aid in rubber compounding.
How does Si-69 (tetrasulfide) differ from Si-75 (disulfide)?
Both couple silica to rubber; the sulfur rank differs. Si-69 is the tetrasulfide (four sulfur atoms, CAS 40372-72-3) and Si-75 is the disulfide (two sulfur atoms, CAS 56706-10-6). The higher sulfur content of Si-69 contributes more to crosslinking and changes scorch behavior.
What is the CAS number and HS code for TESPT?
Bis[3-(triethoxysilyl)propyl] tetrasulfide is CAS 40372-72-3, molecular formula C18H42O6S4Si2. It classifies under HS 2931.90 (organo-inorganic compounds, other); we confirm the destination-specific code on the quote.
How is Si-69 supplied in bulk and can you provide a CoA and SDS?
We supply TESPT/Si-69 in bulk industrial packaging for tire and rubber compounders, with packaging and MOQ confirmed per order. A Certificate of Analysis and Safety Data Sheet accompany shipment; request a bulk quote with your target volume.