Resource Friendly Polycarbonate Production Method Wins Otto-Bayer Medal

Scientists at Germany-headquartered polymer resin manufacturer Bayer MaterialScience have been recognised with an award for a pioneering polycarbonate manufacturing process, which significantly reduces the resources required to manufacture polycarbonate.

The award, the Otto-Bayer medal, has been given since 1984 in memory of the inventor of polyurethane chemisty and former research head at Bayer AG, the parent company of Bayer MaterialScience, Prof Otto Bayer who died in 1982. Despite having the same surname, Prof Bayer is not related to the founder of Bayer Friedrich Bayer, born in Wuppertal, Germany, in 1825.

In the past, polycarbonate from Bayer was made using a continuous melt condensation process, but thanks to progress in catalysis and the availability of innovative high viscosity technologies, the process has been improved considerably. The new manufacturing method is based on a multi-stage, continuous and solvent-free polycondensation sequence using customised evaporation plants, high purity raw materials and an optimised plant design that includes side stream recycling and cleaning. Furthermore, no solvents are needed for polycarbonate production.

The specific energy consumption of the melt process is, on average, 20% lower than with the conventional phase boundary method and the specific water consumption a full 60% lower. This results in a robust process that generates significant cost savings and benefits the environment.

The interdisciplinary team of chemists and engineers from Bayer MaterialScience and Bayer Technology Services (BTS)—comprising Johan Vanden Eynde, Marc Buts, Dr Yun Chen and Dr Rolf Wehrmann—built on earlier successes by colleagues from the Polycarbonates business unit and BTS to achieve long term optimisation of the melt polycarbonate technology and establish the process in Caojing (China).

The site there now operates two 100 metric kiloton melt process lines. To meet the growing market, plans to increase this production capacity are already under way. The economic benefits of the melt process have led to annual cost savings of around €5 mn at the Caojing site.

Image caption: Bayer's Caojing site in China is utilising the innovative polycarbonate melt process technology with two 100 metric kliloton lines.