Silane couping agent KH-SI 69
Product: Silane couping agent KH-SI 69
Chemical Name: Bis(3-triethoxysilylpropyl)tetrasulfide
CAS No.:  40372-72-3                   
Structure formula: (C2H5O)3Si(CH2)3S4(CH2)3Si(OC2H5)3
Typical Physical Properties:                                               
CAS No.:                         40372-72-3                         
Molecular Weight:                 539                                 
Boiling Point<760mmHg>:          250                                  
Flash Point:                       100                                   
Color and Appearance:             Clear yellow liquid             
Density<16/24>:                 1.1+ 0.02                                
Sulfur content(%):                 22.7+ 0.8
  
1-      Si 69 silane, is a bifunctional polysulfidic organosilane for the rubber industry defined chemically as Bis(3-triethoxysilylpropyl)tetrasulfide. It is used to improve the reinforcing capability of fillers with silanol group on their surface (e.g. silicas, silicates, clay, etc.), and also as an integral part of curing systems to improve crosslinking network properties. It has crosslinking and accelerator activity in rubber compounds as a silane coupling agent.
2-      With as little as 0.5 to 1.0 phr with clay fillers and 1.0 to 4.0 phr for silica pigments. It couples the non-black pigment and elastomers resulting in increases in modulus and increase in abrasion resistance.
3-      It has four sulfur atoms positioned in the center. At cure temperatures, these participate with sulfur in producing polysulfidic crosslinks. It replaces crosslinks broken during cure, resulting in reversion resistant, and with proper compounding, reversion free compounds. This is known as equilibrium cure. The dynamic flex characteristics, E.G., heat generation and crack growth, are dramatically improved.
4-      Removing all sulfur from the compound for NR, SBR, NBR and replacing it with it and certain thiuram accelerators, produces compounds with excellent heat aging characteristics in addition to the coupling effects.