Fibre producer Invista has filed a lawsuit against chemical company Rhodia for alleged theft and misappropriation of a chemical process technology used in the production of nylon 6,6.

Invista originally filed a claim on 15 August, claiming that Rhodia and another chemical firm, DuPont, were "unlawfully using Invista's trade secrets to expand in the nylon chemicals business."

However, on 6 November, Invista amended this New York federal lawsuit to focus on DuPont, and then filed the Delaware lawsuit against Rhodia.

The two suits seek damages and a halt to Rhodia's and DuPont's misconduct, Invista said.

The alleged Invista trade secrets relate to its proprietary process for producing adiponitrile (ADN), a critical intermediate chemical used in the manufacture of nylon 6,6.

Invista said it bought the original technology several years ago from DuPont as part of a $4.2bn transaction.

A statement by Invista said: "When it sold the technology, DuPont agreed not to compete against Invista or invest in competitors for an agreed-upon period, which has yet to expire.

"Public statements by Rhodia and DuPont indicate that Rhodia is using Invista's trade secrets to develop an ADN facility in Asia."

In a separate issue going back to 2004 when DuPont sold its textiles and interiors interests to Invista, DuPont this week sued Invista for unauthorised use of trade secrets in the nylon engineering polymers business.