Prevention of lampblack formation during the aimed degradation of high molecular weight isobutene polymers

摘要

1. A process for the degradation of high molecular weight polyisobutylenes, containing a thermal stabilizer and having an average molecular weight (viscosity average) of more than 2.000.000, to polyisobutylenes having an average molecular weight (viscosity average) of less than 200,000 in screw extruders for up to 3 minutes at 150 to 400 degrees C under shear at a velocity gradient of from 100 to 700 sec**-1 , wherein an alpha-, beta-, gamma- or delta-tocopherol or a mixture thereof is used as stabilizer in an amount of from 5 to 500 ppm, based on the weight of the polyisobutylene.