T 1339/21 (Spray-Drying/P & G) 29-01-2024

1. Claims as granted (Main request) - Inventive step

The Board concluded that the opposition ground under Article 100(a) EPC in combination with Article 56 EPC prejudices the maintenance of the patent as granted for the following reasons:

1.1 According to the opposed patent (see par. [0005]), the alleged invention relates to a spray-drying process intended to prevent overheating of spray-dried detergent powders. This problem is said to be specifically related to low-built highly soluble detergents, i.e. compositions including no phosphates, zeolites and silicates.

1.2 Closest prior art

Document D8 (see abstract and example in par. [0039]) discloses a process for spray-drying a detergent with a composition identical to that described in the example of the patent. The subject-matter of claim 1 differs therefrom in that the spray-drying zone is under a negative pressure of at least -50 N/m**(2).

The parties agreed that document D8 represented the closest prior art. The inventive step argumentation will therefore be formulated starting from this document.

1.3 Problem solved by the invention

1.3.1 According to the patent (see pars. [0005]-[0006]), the object of the invention is to prevent overheating of a low-built detergent composition, a concept which is associated with detergents including no zeolite builders, phosphate builders or silicate salts. This problem is said to be specific to this type of detergents and is solved by operating the spray-drying tower under a vacuum.

1.3.2 The patent includes one example (see paras. [0032]-[0035]) of such a detergent composition which is spray-dried under vacuum. The temperature of the detergent at the outlet is below 150ºC, which indicates that overheating of the detergent is prevented by operating the tower under negative pressure.

1.3.3 In view of the above and in the absence of evidence to the contrary, the board agrees with the respondent that the problem solved by the invention is to propose a process that prevents overheating in a spray-drying process for low-built detergent compositions.

1.4 Obviousness of the solution

1.4.1 Document D3 - a handbook for the production of detergent powders - teaches (see page 66) that the design and operation of spray-drying towers must take into account the thermal efficiency and the heat sensitivity of the product. This document states (see page 70) that the spray-drying towers should be operated at a slight negative pressure, such as 10 mm water column (equivalent to approximately -98 N/m**(2)), to draw air into the base of the tower and cool the detergent powder to about 80ºC.

Document D6 similarly discloses (see col. 2, lines 29-47) that the spray-drying of detergents should be carried out under vacuum conditions to draw cold air and prevent thermal damage of the detergent powder. These documents therefore teach the same solution as claim 1 at issue for solving the technical problem of the invention.

1.4.2 The respondent argued that the problem of overheating was specific to low-built detergents (i.e. containing no phosphates, zeolites or silicates). Since none of the above cited documents concerned such detergents, there was no reason to consult their teachings to solve the underlying technical problem.

Further it argued that, since D8 did not identify the problem of overheating of low-built detergents, a skilled person starting from this document would not even recognise temperature control as a problem and would therefore have no motivation to change the operation of the spray-drying process.

1.4.3 The board notes that, as indicated in the preliminary opinion, it follows from the problem solved by the invention (i.e. to prevent overheating in a spray-drying process for low-built detergent compositions) and from the standard application of the problem-solution approach, that a skilled person starting from D8, a document disclosing the spray-drying of a low-built detergent composition, would look for solutions to prevent overheating of the detergent in the spray-drying process. In this respect, once the technical problem has been formulated, it is assumed that a person skilled in the art would seek solutions to that problem regardless of whether this is suggested in the closest prior art, unless the closest prior art somehow teaches against doing so (in which case the closest prior art may not be an appropriate starting point).

As also concluded in the preliminary opinion, documents D3 and D6 contradict the information in par. [0005] that the problem of powder overheating or temperature control only affects low-built detergents. In particular, D3 and D6 address the problem of heat sensitivity or thermal damage of the product and propose operating the spray-drying tower under negative pressure to draw air and cool the falling powder, which clearly implies that the problem of overheating in spray-drying processes affects detergent products in general and not only low-built detergents.

1.4.4 At the oral proceedings, the respondent argued that there was a fundamental difference between detergents with no zeolites, phosphates and silicates as defined in claim 1 and other detergent compositions. Zeolites, phosphates and silicates had relatively high surface areas, which played a key role in dispersing and drying the liquid components. Without zeolite, phosphate and silicate, liquid surfactants were not well dispersed and, due to their water affinity, formed sticky agglomerates that were difficult to dry.

Notably, in 2004, there was a significant change in regulations where phosphates were first limited and then banned, resulting in consequences for the handling of compositions. Documents D3 and D6 were published before those regulatory changes, so their teachings likely related to detergents containing phosphates and/or silicates. Such detergents could be easily dried, so working under negative pressure to cool down the air inlet of the spray-drying tower did not represent a problem.

The situation was however different for detergent compositions with no zeolites, phosphates or silicates, as in D8. In such cases, the skilled person would have a prejudice to implement a solution involving the cooling of the air in the spray-drying tower, because this would be expected to further hinder the drying of a detergent composition which was known to form sticky agglomerates which were difficult to dry. These issues were furthermore implicitly addressed in document D3, which indicated (see page 64) that the formulation of the composition greatly influenced the structure of the particles and the speed of drying. A skilled person starting from the process in D8 would therefore have a disincentive to implement the solution proposed in D3 or D6.

1.4.5 The Board disagrees with the above argumentation for the following reasons:

As argued by the appellant, low phosphate detergents were not only known but relatively common by the end of the 80s, i.e. several years before D3 was published, so it is not apparent why the teachings in this document should be considered to be limited to detergent compositions including phosphates.

Furthermore, no evidence has been presented that the above discussed problems would indeed occur when drying the detergent composition of D8. These problems are not even disclosed or hinted in the patent. In fact, in the example of the contested patent (which concerns a composition identical to that of D8), the detergent is effectively spray-dried using a tower operating under negative pressure and no particular problem is reported, a result which seems to contradict the respondent's argument.

The respondent argued that the finding that the composition in the patent could be effectively dried with a tower operating under negative pressure was as such unexpected.

However, again, there is no suggestion of this in the patent in question, so that it must be concluded that either the drying of such compositions is in fact not so challenging, or that it is effectively achieved by other means, which in any case are not defined in the claims. Either way, even if it was assumed that the drying of a composition with no zeolite, silicate or phosphate is somehow problematic, this would not prevent the skilled person from contemplating the solution proposed in D3. Instead, the skilled person would seek to find the appropriate balance of operating and/or design parameters to ensure that the cooling effect prevents overheating of the composition without significantly reducing the effectiveness of the drying process (e.g. adjusting the inlet temperature, air flow, tower dimensions, etc.). After all, any solution to reduce overheating is likely to involve reducing or limiting the operating temperature and hence the drying efficiency in some way. It is therefore apparent that the skilled person would choose to find the appropriate balance between the opposing effects of cooling and heating/drying rather than give up on finding an effective solution altogether.

1.4.6 All in all, the Board concludes that a skilled person starting from D8 and seeking a solution to prevent overheating of the detergent composition would contemplate the one proposed in D3 or D6, and in doing so would arrive at the subject-matter of claim 1 in an obvious manner.

1.5 The subject-matter of claim 1 at issue is therefore not inventive in view of the combination of D8 with the teachings of D3 or D6.

2. Since the only request presented by the respondent is not allowable, the patent must be revoked.