Published: May 1995
This supplementary report reviews the technology for producing graft resins of acrylonitrile, butadiene, and styrene (ABS), and copolymer resins of styrene and acrylonitrile (SAN [or ANS if the acrylonitrile content exceeds 50 wt%]) or of a-methyl styrene and acrylonitrile (MSA). Also presented are the economics of producing ABS resins by continuous mass polymerization, emulsion polymerization, and emulsion-mass polymerization; and for producing SAN or MSA resins by continuous mass polymerization.
In recent years, continuous mass polymerization has become the process most widely employed by ABS producers worldwide. With its improved technology, the process can produce resins with enhanced color consistency, thereby making painting unnecessary for certain applications. The mass polymerization process is the most desirable technology from the standpoint of capital investment and environmental issues. However, the emulsion polymerization process, which is still commonly used in the industry in plants built before mid-1980, provides more flexibility in product range than the mass polymerization process. The emulsion-mass polymerization process, which was developed during the late 1970s, was attractive to the industry in the 1980s. According to SRI's evaluation, the process's production costs are lower than those for the continuous mass process; however, it is less environmentally friendly than the continuous mass process, and it is more expensive to build.