Abstract:

The presentation deals with a novel continuous compounding process for SBR-Silica-compounds using co-rotating twin screw extruders.

In Europe modern tires have to meet very demanding requirements with respect to grip in wet condition and to rolling resistance. Tire rolling resistance is the crucial factor. It can only be reduced by the substitution of carbon black for silica as a filler in combination with SBR-Rubber in tire treads.

The mixing process is complicated because of the chemical reactions between silica, silane and rubber. Today batchwise manufacturing of SBR/Silica compounds in internal mixers and roll mills is a complex (3 to 4 steps) and expensive process. With continuous compounding some advantages may be expected: Shorter mixing times, reduced energy consumption, better compound quality. The task of the research reported here is to investigate the potential and restrictions of such a continuous process.

Using a one-stage extruder compounding process, an adequate silanisation and silica dispersion could not be achieved. To attain satisfactory compound properties, a two-stage process is used, which has a significant advantage regarding the mixing quality and process efficiency. Using a machine with 44 mm screw diameter in a two-stage process (extruder cascade) a high degree of silanisation could be achieved. To reach the same level of the mixture quality a remarkable reduction of residence time could be achieved.

Some key features of the process investigated here are depicted in the form of simulation results of mass and energy transport in this type of twin screw extruder.

The results of this research can be a basis for further optimizations of this continuous mixing process and for a first evaluation of compounding costs.

___________________________________

Biography:

Edmund Haberstroh, born in 1948 in South Germany, studied mechanical engineering in Karlsruhe and Aachen. After his graduation in 1976 he was a staff member of the Institute of Plastics Processing (IKV) at RWTH Aachen University, working on extrusion, where he recieved his Ph.D. from Prof. Georg Menges in 1981. He was department head at IKV and after that he worked in the plastics and rubber industry for 10 years in Switzerland and in Germany. In 1995 he was appointed professor for rubber technology at RWTH Aachen University, he was also a visiting professor in Leuven (Belgium). Additionally Prof. Haberstroh is head of rubber process methodology of the German Institute of Rubber Technology (DIK) in Hannover. His research activities are in the fields of rubber processing, polymer compounding and plastics welding.
He is married to the physician Irmgard Leiber-Haberstroh and has three children. His hobby is music.