Process for reducing melt fracture during extrusion of a molten narrow molecular weight distribution, linear, ethylene copolymer

摘要

A process for reducing melt fracture formed during extrusion of a molten narrow molecular weight distribution, linear, ethylene polymer, which comprises extruding said polymer through a die having a discharge outlet defining an exit die gap formed by opposing die lip surfaces and wherein one surface of the die lip and/or die land in contact with the molten polymer extends beyond the opposing surface of the die lip and/or die land in the direction of the axis of flow of the molten polymer through the die exit and wherein said extended die lip has a groove extending around said extended die lip, said groove being disposed opposite the leading edge of the opposing die lip surface whereby melt fracture is reduced on both surfaces of the polymer leaving said die exit.