Chemicals giant DuPont

sued a California company on Wednesday, alleging it sold proprietary information on a lucrative line of specialty paint to Chinese rivals.

USA Performance Technology Inc somehow obtained secret materials on how DuPont produces titanium dioxide, a popular pigment used to make paints for cars, plastics and paper, DuPont said in a filing with the U.S. District Court, Northern District of California.

In the suit, DuPont said the defendants were in the process of providing or have provided specific details on its titanium dioxide production process to one or more of DuPont's competitors in China.

DuPont said it does not know how the trade secrets were stolen from its facilities.

The investigation is ongoing, DuPont spokesman Dan Turner said.

A call to Oakland-based USA Performance was not immediately returned.

DuPont wants USA Performance, as well as employees Walter Liew and John Liu, to pay an amount equal to double actual damages as well as other fees.

DuPont declined to say the final amount it is ultimately seeking.

DuPont is the world's largest producer of the material, also known as Ti02. Ford Motor Co is one of DuPont's biggest Ti02 customers. Texas-based Huntsman Corp is a rival.

DuPont does not break out sales figures for individual products, but in 2010 the unit that contains Ti02 reported revenue of $6.32 billion.

DuPont shares fell 0.3 percent to $55.87 in post-market trading.

The case is E.I. Du Pont De Nemours and Company v. USA Performance Technology Inc, U.S. District Court, Northern District of California.

(Reporting by Ernest Scheyder; editing by Andre Grenon)

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