ESSEN (dpa-AFX) - The criticism of chemicals trader Brenntag by activist investors is not abating. Now they want a seat on the supervisory board, according to a letter dated Tuesday from investor PrimeStone Capital. Thus they underpin their demand to split the enterprise into two parts. Away from these demands, the activist investors criticize the supervisory board's communication with investors as well as its control of the company's management. The move by shareholder PrimeStone Capital follows a meeting in which it failed to convince Brenntag CEO Christian Kohlpaintner to quickly separate the Specialties division from the Essentials business unit. In the first business unit, Brenntag focuses on the distribution of ingredients for selected industries. In the second, the company markets process chemicals. PrimeStone and other activists want to separate the two businesses to improve profit margins and increase the value of the stock.