The product triggers chemical reactions when exposed to UV light which help speed up the drying process for coatings and adhesives. It is protected by several patents covering the synthesis process, which are meant to prevent other companies from using this process to produce Irgacure 819 and certain product formulations.

But after intensive chemical analysis of counterfeit products BASF has proven they were manufactured using its patented synthesis process. These counterfeit versions were all produced in China, according to BASF.

BASF said in a statement that after repeatedly issuing notifications it had contacted distributers that were selling counterfeit Irgacure 819 and legally insisted they stop marketing and selling them. It said one distributer had already said it would withdraw this product from the market immediately.

A spokeswoman for BASF could not confirm how many distributers were selling the product, as she said it was still in discussions with some of them. She would also not name any of the distributers.

"We do not know the exact amount of product that was sold nor the volumes that are still out there, but these sales have been on going for several years, and therefore the amount must not be negligible," she added.

BASF head of pigments and resins business in Europe Ralf Spettmann said it expected all distributers would respect its patents rights and that no court rulings would be necessary. "The observance of patent rights is extremely important for us to protect our intellectual property and to foster innovation in research and development," he said.