Key points
- Claim 1 is directed to a fouling control coating composition comprising a polysiloxane-based binder system, a polysiloxanes component, and "one or more biocides" in a specified weight ratio.
- "the coating composition of example 5 of D4 described in table 1 on pages 20 and 21 of that document which embodies [a] traditional silicone anti-fouling coating formulation is a suitable starting point for assessing inventive step of the subject-matter of operative claim 1. The Board has no reason to have a different opinion."
- "it is undisputed that the composition of operative claim 1 differs from the closest prior art only in that it comprises one or more biocides, wherein the weight ratio between the one or more hydrophilic-modified polysiloxanes and the one or more biocides is in the range 1:0.2 to 1:6."
- An extensive analysis of the technical effect based on the admitted evidence follows.
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While the Board accepts that the addition of a biocide in the weight ratio defined in operative claim 1 leads to an improved anti-fouling performance of the coating composition, the appellant [proprietor] did not submit that the hydrophilic-modified polysiloxane(s) and the biocide(s) when used in combination provide an antifouling effect going beyond the sum of the anti-fouling effects brought about by each of these compounds, i.e. did not submit that those act synergistically. The Board has no reason to have a different view, in particular since the experimental tests submitted are in any event not designed to demonstrate such synergism.
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" In view of the above, having regard to the antifouling effect of biocides, the absence of any evidence for the criticality of the range of weight ratios between the one or more hydrophilic-modified polysiloxane(s) and the one or more biocide(s) defined in operative claim 1 and the absence of any synergy between these two compounds, the Board is satisfied that the problem successfully solved by the claimed coating compositions over the closest prior art is to be formulated as the provision of a coating composition having improved long-term anti-fouling performance."
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" It remains to be decided wether the skilled person desiring to solve the above problem would, in view of the disclosure of D4, possibly in combination with other prior art documents or with common general knowledge, have modified the composition of example 5 or D4 in such a way as to arrive at the composition of operative claim 1. The respondent '[opponent] referred in this respect in particular to D4 [itself]. ... D4 teaches in claim 6 that the curable composition may contain in addition to components (A) and (B) an antifouling agent"
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" The mere indication of the numerical range for the ratio between the hydrophilic-modified polysiloxane(s) and biocide(s) defined in claim 1 is neither critical nor can it be seen as a purposive choice for solving the problem underlying the patent in suit. On this basis, the additional use of a biocide in an arbitrary amount relative to the amount of hydrophilic-modified polysiloxane which is defined in present claim 1 can only be seen as an obvious measure for the skilled person faced with the problem of providing a coating composition having improved long-term anti-fouling properties. "
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"Referring to the experimental data on file the appellant [proprietor] also argued that the magnitude of the additional antifouling effect resulting from the use of a biocide in the proportions specified in operative claim 1 would be surprising for the skilled person, rendering non obvious the addition of the biocide defined in operative claim 1."
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"This is also not convincing. Having regard to the suggestion in D4 itself, also in line with the teaching of D2 and D9, addressed in the above paragraph, the skilled person expects an additional antifouling effect brought about by biocide compounds. In such as case, where it is obvious from the state of the art that a certain measure, here the addition of a biocide, will bring about an improvement of a certain property, here antifouling properties, a surprising degree of this improvement cannot make this per se obvious measure non-obvious (Case Law, supra, I.D.10.8, in particular T 551/89 of 20 March 1990). [note, this reasoning seems obiter, see the next sentence]
Moreover, in the present case, the appellant did not even explain, let alone provide evidence for the scale of improvement which would be expected by the skilled person when using biocide(s). On that basis, the appellant's argument based on the alleged surprising magnitude of the improvement of antifouling properties obtained with the present invention cannot be retained." -
I'm not sure if this is a valid reasoning. If some combination is truly synergystic, I would expect it to be inventive. T 551/89 seems obiter itself, and also explains that the suprisingly large effect (would there be any) is to be treated as a bonus effect which does not contribute to inventive step.
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EPO
source http://justpatentlaw.blogspot.com/2023/07/t-052418-synergistic-effect-would-be.html
