Tetrasulfide Silane Coupling Agent Crosile® 69 for Rubber

Silane coupling agent Crosile®69 is a bifunctional, sulfur-containing organosilane for rubber tyres in combination with white fillers containing silanol groups.

Item NO.	Crosile® 69
Chemical Name	Bis [3-(triethoxysilyl) propyl] tetrasulfide
Chemical Formula	C18H42O6S4Si2
CAS No.	40372-72-3
EINECS No.	254-896-5
Properties	1. Sulfur containing organosilane modified Silica 2. Greater tensile strength 3. Reduced compression set 4. Increased abrasion resistance 5. Low rolling resistance

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Product Description

Silane coupling agent Crosile® 69 Bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) is commonly used as a silane coupling agent, crosslinking agent, and reinforcing additive in rubber manufacturing. It improves the interaction between inorganic fillers and rubber polymers, enhancing the mechanical properties and processing performance of rubber compounds.

TESPT is widely used in tire compounds and other technical rubber products. It can also form protective films on metal substrates and serves as an important intermediate in the synthesis of silicon-based materials.

Chemical Identity

Chemical Name: Bis [3-(triethoxysilyl)propyl] tetrasulfide, Silane 69, TESPT
CAS Number: 40372-72-3
Molecular Formula: (C2H5O)3SiCH2CH2CH2-S4-CH2CH2CH2Si(OC2H5)3
Equivalent Type: Bis(3-triethoxysilylpropyl)tetrasulfane, Bis(3-(ethoxysilyl)propyl)tetrasulfide, Bis(triethoxysilylpropyl)tetrasulfane, Bis[3-(triethoxysilyl)propyl]tetrasulfide, Tetrasulfane, Bis(3-Triethoxysilylpropyl), Silane coupling agent

Key Features

Silane Coupling Agent: Acts as a silane coupling agent in rubber manufacturing, improving the interaction between inorganic fillers and rubber polymers.
Crosslinking & Reinforcing Additive: Functions as a crosslinking agent and reinforcing additive in rubber manufacturing.
Protective Film Former: Forms protective films on metal substrates.
Synthesis Intermediate: Serves as an important intermediate in the synthesis of silicon-based materials.

Performance Improvement

Mechanical Strength: Improves tensile strength, tear strength, and abrasion resistance.
Compression Set: Reduces compression set.
Filler Dispersion: Enhances filler dispersion.
Processability: Lowers compound viscosity and improves processability.
Vulcanizate Properties: Contributes to improved overall mechanical properties of vulcanizates.

Technical Specifications

Properties	Units	Target Values (Spec, Limits)
Alcohol content	%(wt)	≤0.5%
CLPTES Content	%(wt)	≤3.0%
Other impurity content	%(wt)	≤1.0%
Viscosity 25°C (cps)	Cps	≤14.0
Sulfur Content	%(wt)	22.5 (21.7-23.3)
Average chain Length	–	3.70 (3.55-3.85)
S2 content	%(wt)	18.0 (15.0-21.0)
S3 content	%(wt)	30.0 (27.0-33.0)
S4 content	%(wt)	24.0 (21.0-27.0)
S5 to S8 content	%(wt)	27.0 (24.0-30.0)
Volatility (100°C / 10 min.)	%	≤1.0%
Specific Gravity (25°C)	–	1.080 ± 0.020
Refractive Index (25°C)	–	1.480 ± 0.020

Application Scenarios

Tire Compounds: Designed for silica-filled rubber compounds and tire applications; improves filler-rubber interaction and reinforcement efficiency.
Technical Rubber Products: Widely used in other technical rubber products, and can form protective films on metal substrates.
Silica-Type Fillers: Compatible with silica, talc, mica, kaolin and other hydroxyl-containing minerals.
Unsaturated Rubber Systems: Suitable for NR, IR, SBR, BR, NBR, EPDM and other unsaturated rubbers or their blends.

Usage Guidelines

Typical dosage: 1.0–4.0 PHR (parts per hundred rubber)

Packaging And Transportation

Packing: 25 kg/drum (16 MT/20 FCL with pallet); 200 kg/drum (16 MT/20 FCL with pallet); 1060 kg in IBC drum (21.2 MT/20 FCL with pallet)
Storage: Kept at a low temperature, dry and ventilated place, avoid direct sunlight.
Shelf life: One year in ventilated, cool and dry area.

This Tetrasulfide Silane is part of the Crosile® Sulfur and Mercapto Silane Coupling Agents range for silica-reinforced rubber and tire compounds.