Zusammenfassung von EPC2000 Art 056 für die Entscheidung T1779/19 vom 11.01.2023

T 1779/19 concerned an appeal against the decision to reject the opposition against the European patent, which disclosed in claim 1 a "Method for preventing chlorine deposition on the superheater of a boiler in which a fuel with a chlorine content is burned, and to which boiler a compound with a sulphate content is fed in the superheater area [...] characterized in that the said compound is ferric(III) sulphate, Fe2(SO4)3 and/or aluminium(III) sulphate, Al2(SO4)3, and the said compound as a water solution and in a drop size of 1-100 µm". The board identified document D5 as the closest prior art. The appellant (opponent) argued that following the principles set out in T 666/89, the definition of a step of feeding a solution of ferrous sulphate in D5 implicitly encompassed feeding a solution of ferric sulphate, because Fe(III) spontaneously reacted in contact with air to give Fe(II), so that at least a portion of the ferrous sulphate would be in the form of ferric sulphate. The board did not agree. With reference to T 12/81, T 666/89 and in particular T 270/97, the board stated that the key requirement for such an implicit disclosure was inevitability. To implicitly anticipate a given product, the prior art document must disclose a reaction carried out under specific conditions which would inevitably lead to the product in question. The board did not contest that ferrous sulphate was oxidised to ferric sulphate in the presence of air. There was however no basis to conclude how far this reaction would go in D5, which did not disclose a reaction but a solution of ferrous sulphate, and there was no information in D5 how this solution was made and how long and under which conditions it should be stored. The presence of ferric sulphate was thus highly likely or even certain, but there was no way to conclude that this presence would go beyond trace levels. The board further found that there was no evidence that the invention provided an improved effectiveness when compared to a method of preventing chlorine deposition using a ferrous sulphate solution as disclosed in D5. The proposed solution therefore did not successfully solve the problem presented in the patent. However, the board considered that the experiments in the patent at least demonstrated that the claimed method performed significantly better than other known alternatives. This implied that the claimed additives had been identified as particularly effective for the purpose of preventing chlorine deposition, so they could not be considered to be arbitrarily selected. Thus, the claimed subject-matter did not simply provide a (general or arbitrary) alternative, but rather an alternative which was highly effective when compared to other commonly used additives. The problem to be solved was therefore reformulated as the provision of an alternative method which ensured a high effectiveness in the prevention of chlorine deposition. Considering obviousness, the board found that a skilled person seeking to solve the underlying problem of finding alternatives which were highly effective in preventing chlorine deposition would consult D4, and that in doing so it would consider using ferric sulphate as an additive in the method of document D5 without the need of inventive skills. As to the obviousness of using a droplet size of 1 to 100 µm, the board noted that, since the patent did not indicate how the feature "a drop size of 1-100 µm" should be interpreted, all technically reasonable alternatives should be considered to be covered by the claim. The interpretation proposed by the proprietor was also rather broad, only excluding sprays with significantly coarse droplet sizes. It further acknowledged that the patent did not associate the droplet size with any specific technical effect, and that the examples of the patent did not even specify the droplet size in the tests, so this feature could only be considered as providing an alternative. The board concluded that the relevant question to assess the inventiveness of this feature was whether a skilled person starting from D5 would have considered spraying non-coarse droplets as an obvious alternative. In view of the teachings in D5, the board concluded a skilled person would readily understand that coarse droplet sizes should be avoided and that the nozzles used in the relevant embodiment of figures 1 and 2 should be configured to form relatively small droplets. In doing so the skilled person would arrive at the droplet size range defined in claim 1 without exercising inventive skill. The subject-matter of claim 1 as granted was obvious and therefore not inventive in view of D5 combined with the teachings of D4, and so did not meet the criteria set out in Art. 56 EPC.