Rhodia S.A.'s Silica Systems unit has introduced a silica intended to bridge the gap between precipitated and fumed silicas-both from a price and performance standpoint.
``In terms of properties, there is a real gap in precipitated vs. fumed,'' said Vincent Bordereau, Rhodia global business manager of elastomers and plastics. He talked about the new silica during the International Silicone Conference, held May 25-26 in Cleveland.
Rhodia said its patented Siloa-brand amorphous synthetic silica allows higher purity production with less sensitivity to moisture and high dispersability compared with traditional precipitated silica grades. Its controlled surface chemistry also improves bead surfaces significantly, resulting in nano-level surface order with virtually no surface defects or dusting.
Bordereau said Siloa also bridges the features of precipitated and fumed silicas in moisture absorption, which is important for extruded and molded applications; dielectric strength, for cabling applications; and compression set, tensile strength and tear resistance, for tubing applications. Potential product applications range from automotive gaskets to computer keyboards.
Of the global silica market, he said precipitated makes up about 90 percent of volume and costs $1 to $1.50 a kilogram. These silicas are used in such applications as tires, footwear outsoles, some silicone elastomers, and some feed and food additives as a carrier.
Fumed silicas, making up the other 10 percent, are more expensive, costing from $4 to $7 a kilogram, he said. Much of the fumed silicas wind up as fillers in silicone elastomers and give much better mechanical properties in all cases except for compression set.
Calling Siloa a ``macro change in chemistry,'' Bordereau said Rhodia previously offered just precipitated silica. This new offering, he added, will give customers a material that has a significant boost in performance over precipitated but, at $2.50 a kilogram, costs much less than fumed.
``The intent is not to take on fumed, but to help customers get a more economical solution,'' Bordereau said. ``It won't replace fumed, but open new possibilities to compounders. It's up to them to decide what they want to do with it.''
Rhodia's launch of Siloa for the North American market at the International Silicone Conference was the second of a three-phase rollout. In April it made the product available in Europe and will take it to the Asian market in late June or early July.
The company has a dedicated line for Siloa at its plant in Incheon, South Korea, where it makes silica for silicone applications. The line has annual capacity of 3,000 metric tons, and the factory's product mix can be altered for future expansion.
Thus far, output for Siloa has been just about 25 tons a month, Bordereau said, but that is scheduled to double this summer and reach 100 tons a month by the end of the year. Only one grade-Siloa 72X-currently is available, but there should be three or four other grades available by the end of the year.