Currently, ABS is produced by two different technologies: emulsion and continuous mass. Both technologies can produce materials with peculiar properties, but not always overlapping. The emulsion technology is more suited to produce high-performance materials for the injection molding sector. On the other hand, the continuous mass technology is more suited to produce high performance materials for the extrusion sector. In the ABS emulsion technology, polymerization is carried out starting from butadiene monomer while, in continuous mass, polymerization is carried out in presence of a preformed rubber.
The ONE-STEP® technology has been developed by Versalis to fill the above-mentioned gap and to further rationalize the process scheme, by eliminating redundant steps in the production and supply of the rubber. Moreover, this technology allows to widen the range of product morphologies obtainable; in fact, by avoiding the finishing and packaging section, the ONE-STEP ® technology, fully overcomes the constraints linked to rubber production, expanding the available rubber molecular weight range that can be used in the synthesis of continuous-mass ABS.
Versalis has designed and tested at pilot plant scale (kg/h of product) the above-mentioned new process scheme that integrates the two well proven and consolidated proprietary technologies for producing the rubber (anionic polymerization of butadiene) and mass ABS (radical polymerization of acrylonitrile-styrene). According to the new ONE-STEP® technology, the rubber solution from the anionic reaction is no longer steam stripped and finished in bales, but it is processed in a new non-conventional unitary operation, in which the solvent is exchanged with styrene, recovered and recycled.
Moreover, due to important process simplifications, the ONE-STEP ® technology significantly reduces investment and operating costs, as well as the CO2 footprint.