Sulfur silane coupling agents (SCA-A69X and SCA-S75X) and mercapto silane coupling agents (SCA-S89M and SCA-S89E, etc.) have a very significant modification effect on white carbon black, which can significantly improve the compatibility and reinforcing effect between white carbon black and rubber. They can significantly reduce the Mooney viscosity, heat generation and rolling resistance and the processing property of the rubber compound, and significantly improve the wear resistance of the vulcanized rubber. The introduction of silane coupling agent makes the application of white carbon black in the rubber industry advance rapidly, especially in the "green" low rolling resistance tire filled with all-white carbon black, the role of silane coupling agent is even more powerful and indispensable. In radial tires, silane coupling agents can also significantly improve the adhesion of the compound to the steel wire.
In addition to tires, silane coupling agents are also used in some other non-carbon black filled light-colored rubber products, such as sports shoe soles, rubber rollers, etc., which are also important for improving the wear resistance of the products. Other rubber products such as rubber hoses, tapes, rubber miscellaneous pieces, etc., especially some non-carbon black fillers filled rubber products(such as white carbon black, kaolin and others).
According to the rubber vulcanization system, the sulfur vulcanization system rubber generally uses sulfur silane coupling agent (SCA-A69X and SCA-S75X) and mercapto silane coupling agent (SCA-S89M and SCA-S89E, etc.); Vinyl silanes (SCA-V71E and SCA-V71C) are generally recommended for peroxide vulcanized rubbers such as silicone rubber and EPDM rubber.
The using methods of silane coupling agent currently mainly include a direct mixing method and a pretreatment method. In the direct mixing method, the silane coupling agent, the inorganic filler and the rubber are uniformly mixed (opening or kneading) in a certain ratio, and then other additives are added. So that it will not prevent the silane coupling agent from coating the surface of the filler. Usually the silane coupling agent is added to 1-2% of the compound. The advantage of this method is that the dosage can be adjusted, the process is simple, but the dispersion effect is not very satisfactory.
The pretreatment method is to first pretreat the surface of inorganic filler with a silane coupling agent by a high agitator, and then mix the surface modified filler with rubber and other auxiliary agents. Usually, the silane coupling agent is added to the filler amount. 1~2%. The advantage of the method is that the modification effect is relatively good, and the silane coupling agent coats the filler firstly, and the utilization efficiency is high; but it will need extra work and equipment.