Preformed sheet layers of multiple high-performance polyethylene (hppe) multifilament yarn monolayers and ballistic-resistant assemblies comprising the same

Abstract

Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DR; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DRof at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DR=DR*DRof at least 150, wherein DRis the draw ratio in the spinholes and DRis the draw ratio in the air-gap, with DRbeing greater than 1 and DRat least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.