A US court has imposed a 20-year ban on Korean company Kolon to stop it from making and selling its Heracron aramid fibre, in a ruling that marks the end of a three-year battle in which DuPont accused the company of stealing trade secrets relating to its own Kevlar high strength fibres used in products like body armour.

The injunction comes after DuPont was awarded $920m in damages last September.

"Kolon Industries wilfully and maliciously misappropriated DuPont's proprietary Kevlar technology," said Thomas Sager, DuPont senior vice president and general counsel. 

"The trial court ordered Kolon to not produce, market or sell any para-aramid fiber products, worldwide, for 20 years; it also permanently enjoined Kolon from using any of the trade secrets it stole from DuPont. 

"Additionally, Kolon has until 1 October to remove and return DuPont's trade secrets or face contempt proceedings."