Rubber — Process Challenge

Sulfur Silanes for Silica Tire-Tread Coupling

Coupling silica filler into the rubber network in silica-filled tire tread for low rolling resistance and high wet grip using sulfide/mercapto silanes, supported by the sulfur cure system
Updated Jun 2026
Solution Approach

RawSource supplies the base chemicals that go into these programs. We can help with product selection, grade matching, and sourcing from multiple origins for supply security.

Typical Formulation Workflow
1
Polymer & Process Definition
Identify the resin and process (extrusion, molding, film) and the targets — thermal stability, clarity, flame retardance, slip, or color.
2
Additive Selection
Match stabilizers, antioxidants, plasticizers, lubricants, flame retardants, or masterbatch carriers to the polymer and processing temperatures.
3
Compounding Trial
Confirm loading and dispersion on a compounding or molding trial, checking processability, mechanicals, and aesthetics against the control.
4
Validation & Scale-Up
Verify long-term performance (heat aging, migration, weathering) and lock the formulation, packaging, and lot specs for production.
Recommended Chemistries (6)
Bis-(3-triethoxysilylpropyl)-tetrasulfide (Si-69 / TESPT)
CAS 40372-72-3
Silicone Fluids & Oils
Tetrasulfide silane for tires
Ethoxysilyl ends bond silica silanols while the tetrasulfide bridge reacts into the polymer during vulcanization, chemically linking filler to rubber to lower hysteresis (rolling resistance)
Physical Description: Liquid; Liquid, Other Solid; Other Solid; Dry P…
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Bis--disulfide (Si-75 / TESPD)
CAS 56706-10-6
Silicone Fluids & Oils
Disulfide silane for green tires
Disulfide analogue with fewer labile sulfurs for better scorch safety and processing control in green-tire silica compounds
Physical Description: Other Solid; Liquid; Pellets or Large Crystals,…
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Mercaptopropyltrimethoxysilane (MPTMS)
CAS 4420-74-0
Silanes & Organosilanes
Mercapto silane for rubber
High-activity mercapto coupling agent; the thiol bonds efficiently into the rubber network for strong silica-polymer coupling
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Zinc Oxide
CAS 1314-13-2
Mineral Fillers & Pigments
Vulcanization activator
3077 (ZINC OXIDE, CRUDE) · Class
Cure activator that forms the zinc-accelerator complex driving efficient sulfur crosslinking of the compound
Melting Point: 1975 °C   Density: 5.61   Solubility: 0.0004 % at 18 °C
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Stearic Acid
CAS 57-11-4
Acids & Salts
Processing aid and activator
Co-activator that solubilizes ZnO into active zinc soaps and aids filler dispersion/processing
Melting Point: 69 °C   Boiling Point: 383 °C at 760 mmHg   Density: 0.86 at 20 °C
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2-Mercaptobenzothiazole (MBT)
CAS 149-30-4
Specialty Additives
Thiazole accelerator
2811 (2-MERCAPTOBENZOTHIAZOLE) · Class
Thiazole accelerator that speeds and controls the sulfur vulcanization the silane couples into
Melting Point: 177–181 °C   Boiling Point: Decomposes   Density: 1.42 at 20 °C
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