Published June 1998
ICI Acrylics (Belgium), a subsidiary of ICI International (United Kingdom) and one of the largest acrylics producers, has entered into an agreement with Mitsubishi Rayon (Japan) to jointly develop a polymethyl methacrylate (PMMA) recycling technology on a commercial scale. ICI is building a plant of 6.6 to 11 million lb/yr (3,000-5,000 t/yr) recycling capacity in Hertfordshire, United Kingdom, in collaboration with Mitsubishi. This unit is expected to come on stream in 1998. The ICI recycling unit will use scrap PMMA material from production waste, used bathtubs, and billboards. Some auto parts and construction materials are also expected to be included in the feed list in the longer run. Mitsubishi Rayon has its own acrylic resin recycling unit of 4.4 million lb/yr (2,000 t/yr) capacity operating at its Toyoma factory in Japan.
In the ICI process, the PMMA scrap is crushed and pulverized. The decorative and protective coating over the polymer material is washed out chemically. The granules are water-washed, dried, and fed to a depolymerization furnace where they are depolymerized to obtain a gaseous product containing about 98% methyl methacrylate (MMA). Additives, fillers, and dyes are left in the furnace and are discharged as waste. The gaseous stream from the reactor is condensed. After removing the noncondensable gases formed in the reaction, the MMA-containing stream is fed to a distillation tower to obtain MMA of a high purity. Reaction by-products are discharged from the bottom of the column.
This Review presents PEP's conceptual version of ICI's PMMA recycling technology. The PEP process design, based on Mitsubishi Rayon patent JP O9324068 and on published ICI information, is for a PMMA recycling plant with a capacity of 22 million lb/yr (10,000 t/yr) at a 0.9 stream factor in the U.S. Gulf Coast region. Our design may not exactly reflect the actual recycling practice that ICI will adopt for its plant.