MEXICAN firm Industrias Negromex and Cooper Tire & Rubber have been assigned a patent (8,357,733) developed by five co-inventors for making silane, hydrophobated silica, silica masterbatch and rubber products.”
The co-inventors are Peter J. Wallen, Gregory C. Bowman, Howard A. Colvin, Christopher J. Hardiman and Jose Eduardo Rojas Reyna.
According to the patent published by the US Patent and Trademark Office, the invention provides a process for making silica-filled rubber masterbatch using silica hydrophobated with a trimethoxy silane coupling agent that is soluble in an alcohol-water solution containing at least about 70 wt. % water.
One embodiment uses a mixture of trimethoxy silanes, one or more of which react with rubber to bond the silica to the rubber, and one or more of which do not react with rubber, but do hydrophobate the silica.
Hydrophobated silica is mixed with latex polymer and incorporated into rubber during coagulation of the latex, which is preferably coagulated with calcium chloride. The present invention further provides a process for making the trimethoxy silane coupling agents. Preferred trimethoxy silane coupling agents include bis-(3-trimethoxysilylpropyl)-disulfide and bis-(3-trimethoxysilylpropyl)-tetrasulfide.
Rubber products, particularly tyres, compounded with the inventive silica masterbatch can be processed for a long time before scorching because the silica masterbatch provides a long scorch time, according to the patent.RJA
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