Where the invention concerns improving a process to manufacture a known chemical compound, then the closest prior art is confined to documents describing that compound and its manufacture. Comparison with these alone shows whether an improvement has been achieved which can thus be taken into account in formulating the problem the invention sought to solve (T 641/89, T 961/96, T 713/97, T 948/01, T 833/02, T 339/03). In the case of inventions concerning a special process for use with a particular chemical substance having necessarily specific characteristics, determining the closest prior art must involve, above all, considering only those documents which describe a generically corresponding process for using precisely this particular chemical substance with its specific characteristics (T 1285/01, T 354/03, T 1652/08). This accurately and objectively reflects the actual situation in which the skilled person found himself on the priority date of the contested patent (T 793/97).
In T 325/97 the board saw no reason why the above considerations regarding the closest prior art should not also apply to production processes for subject-matter other than a chemical compound and in the case in hand identified the problem to be solved as providing an improved method for the manufacture of a patch for the controlled transdermal delivery of nicotine. In T 373/94 the board also applied the principles and conclusions laid down in T 641/89 where the invention related to the improvement of a manufacturing process for prefilled plastic syringes.
In T 2210/19 the board defined the problem as the provision of a further process for producing a chromium catalysed ethylene copolymer powder. It explained that the skilled person, looking for a further process, would consider variations of the process already known from the closest prior art, taking into account the common general knowledge in the field and the knowledge made available in the prior art. This included variations of any of the parameters of the process that could be expected to be suitable to carry out alternative processes without exercising any inventive activity. As the problem was simply the provision of a further process, no further motivation was needed by the skilled person to perform the modified process.