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.
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.
" 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."
" 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"
" 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. "
"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."
"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 don't find this reasoning entirely convincing. If some combination is truly synergystic, I would expect it to be inventive. The relevant point of T 551/89 seems obiter, the Board in that case was not convinced that a synergistic efect was obtained.
EPO
Obviousness of the solution
25. 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 referred in this respect in particular to D4.
As indicated in above point 15, D4 teaches in claim 6 that the curable composition may contain in addition to components (A) and (B) an antifouling agent, whereby claim 6 referring to any of the preceding claims suggests that an antifouling agent can be used in addition to silicone oil (C) defined in claim 4, which can be either methylphenyl silicone oil and/or polyether-modified silicone oil, i.e. a hydrophilic-modified polysiloxane. Moreover, the antifouling agents listed in the description (paragraph [0081] to [0086]) are all biocides, the amount of antifouling agent in the coating composition being preferably in the range of 0.5 to 10% by weight (paragraph [0087]).
D17a (page 3, section recommended use rates), D17b (page 2, section recommended use levels) and D17c (section antifouling efficacy, third paragraph) confirm that levels of biocides falling within that range are used for marine antifouling coating compositions.
26. 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.
Having regard to the amount of hydrophilic-modified polysiloxane used in example 5 of D4, i.e. 5 wt%, it can be seen that the preferred amount of antifouling agent preconised in paragraph [0087] of D4 leads to a weight ratio between the one or more hydrophilic-modified polysiloxane(s) and the one or more biocide(s) which falls almost entirely in the range defined in operative in operative claim 1, as stressed by the respondent.
27. The appellant argues additionally that at the date of filing of the patent in suit the skilled person would not have expected that the addition of biocide(s) would improve the antifouling performance of the polysiloxane based coating. Reference was made to experiments of Milne and Callow reported on page 698 of D6 and the indication therein that a non-biocide containing control for a series of room-temperature vulcanising (RTV) silicone rubbers was better than the experimental materials that contained biocides. As shown in section 26.7 on page 707 of D6, information about the work of Milne and Callow addressed in D6 is to be found in D6b. As pointed out by the appellant, the observation that "the non-biocide-containing control for this series was a better antifouling than the experimental antifouling material containing biocides and that even the slime fouling which the control accumulated was remarkably non-adherent which serendipitously convinced us of the real possibilities of non-toxic antifoulings" is reported in D6b, on page 229, right-hand column, last full paragraph. The statement refers to experiments carried out in the early 1970s, as can be seen from the first three full paragraphs on page 230 of D6b. The exact nature of the RTV silicone rubbers is not specified.
Based on D6b and D6, the latter being considered by the appellant to represent the common general knowledge, it is the appellant's opinion that the skilled person would rather have expected that the addition of biocide would lead to a decrease of the antifouling performance, therefore teaching the skilled person away from the presently claimed solution.
The appellant's position is however untenable when D4, whose example 5 is taken as the closest prior art, itself unmistakably teaches for its polysiloxane based coating compositions the addition of antifouling agents (paragraphs [0019], [0064] and claim 6) which are biocides (paragraphs [0081] to [0087]). Moreover, D6 does not state that the addition of biocides to silicone rubbers is generally known in the art to decrease their antifouling effect. D6 merely refers to a single document D6b reporting a few experiments with silicone rubbers whose nature is however only vaguely defined.
Moreover, as pointed out by the respondent, the much more recent publications D2 (claim 1, column 1, line 55 to column 2, line 15) and D9 (page 3, lines 1-6; page 14, lines 27-36; page 15, lines 31-36; claim 1) recommend the combined use of organopolysiloxane(s) and biocide(s), in line with the teaching of D4. The appellant's argument that D2 would concern encapsulated biocide and therefore would not be relevant fails to convince, as the use of such encapsulated biocides falls within the scope of present claim 1, as confirmed by the general teaching of the patent in suit in paragraphs [0056] and [0057] and illustrated by top coat composition M in paragraph [0130].
Referring to the experimental data on file the appellant 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.
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). 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.
Conclusion
28. Consequently, starting from the coating composition of example 5 of D4 and faced with the problem of providing a coating composition having improved long-term anti-fouling performance, the skilled person would have found it obvious to add a biocide to that composition in the weight ratio between the one or more hydrophilic-modified polysiloxane(s) and the one or more biocide(s) specified in present claim 1, arriving thereby in an obvious way at coating compositions falling within the ambit of claim 1 of auxiliary request B1.
Auxiliary request B1 is therefore not allowable, as its subject-matter is devoid of an inventive step.
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