Patent ID: 6913729
Filing Date: 2005-07-05
Classification: B29C,B29K,B29L,Y10T

Abstract:
1. A process for producing a large polyethylene blow molding having a volume of from 5 to 5,000 l and having a bursting strength determined by a drop height test at −18° C. of more than 3 m, by forming polyethylene having a density ρ≧0.94 g/cm 3 , a melt flow rate MFR 190/21.6<50 g/10 min and a notched tensile impact strength a zK (−30° C.) not less than 250 kJ/m 2 , at high temperatures to give a large blow molding having a volume of from 5 to 5,000 l, and allowing the blow molding to cool to room temperature, and, in a further step, annealing the blow molding at from 60 to 135° C. until the notched tensile impact strength a zK (−30° C.), measured in accordance with ISO 8256, is at least 300 kJ/m 2 , and then cooling the same again to room temperature.