AKRON (Aug. 1)—The European Patent Office has reversed an earlier decision concerning the validity of Flexsys S.A.´s patent position for the production of a key intermediate for the firm´s Santoflex para-phenylenediamine (PPD) rubber stabilizers. The basic patent covering the Flexsys technology previously had been challenged successfully in the European Patent Office by Vucht A.S. of Bratislava, Slovak Republic, a Flexsys spokesman said. However, the EPO's board of appeal has now reaffirmed the patent, which covers 4 amino- diphenylamine (4-ADPA), according to a Flexsys statement. "This decision is finalàand secures the protection of the proprietary PPD technology for the next foreseeable future," the group said. Flexsys´ patented process involves reacting aniline and nitrobenzene in the presence of a suitable base and a controlled amount of protic material. The resulting intermediates are transformed into PPD via a reduction process.